Merge tag 'irq-urgent-2023-03-05' of git://git.kernel.org/pub/scm/linux/kernel/git...

[platform/kernel/linux-starfive.git] / drivers / mtd / spi-nor / core.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Based on m25p80.c, by Mike Lavender (mike@steroidmicros.com), with
 * influence from lart.c (Abraham Van Der Merwe) and mtd_dataflash.c
 *
 * Copyright (C) 2005, Intec Automation Inc.
 * Copyright (C) 2014, Freescale Semiconductor, Inc.
 */

#include <linux/err.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/spi-nor.h>
#include <linux/mutex.h>
#include <linux/of_platform.h>
#include <linux/sched/task_stack.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/spi/flash.h>

#include "core.h"

/* Define max times to check status register before we give up. */

/*
 * For everything but full-chip erase; probably could be much smaller, but kept
 * around for safety for now
 */
#define DEFAULT_READY_WAIT_JIFFIES              (40UL * HZ)

/*
 * For full-chip erase, calibrated to a 2MB flash (M25P16); should be scaled up
 * for larger flash
 */
#define CHIP_ERASE_2MB_READY_WAIT_JIFFIES       (40UL * HZ)

#define SPI_NOR_MAX_ADDR_NBYTES 4

#define SPI_NOR_SRST_SLEEP_MIN 200
#define SPI_NOR_SRST_SLEEP_MAX 400

/**
 * spi_nor_get_cmd_ext() - Get the command opcode extension based on the
 *                         extension type.
 * @nor:                pointer to a 'struct spi_nor'
 * @op:                 pointer to the 'struct spi_mem_op' whose properties
 *                      need to be initialized.
 *
 * Right now, only "repeat" and "invert" are supported.
 *
 * Return: The opcode extension.
 */
static u8 spi_nor_get_cmd_ext(const struct spi_nor *nor,
                              const struct spi_mem_op *op)
{
        switch (nor->cmd_ext_type) {
        case SPI_NOR_EXT_INVERT:
                return ~op->cmd.opcode;

        case SPI_NOR_EXT_REPEAT:
                return op->cmd.opcode;

        default:
                dev_err(nor->dev, "Unknown command extension type\n");
                return 0;
        }
}

/**
 * spi_nor_spimem_setup_op() - Set up common properties of a spi-mem op.
 * @nor:                pointer to a 'struct spi_nor'
 * @op:                 pointer to the 'struct spi_mem_op' whose properties
 *                      need to be initialized.
 * @proto:              the protocol from which the properties need to be set.
 */
void spi_nor_spimem_setup_op(const struct spi_nor *nor,
                             struct spi_mem_op *op,
                             const enum spi_nor_protocol proto)
{
        u8 ext;

        op->cmd.buswidth = spi_nor_get_protocol_inst_nbits(proto);

        if (op->addr.nbytes)
                op->addr.buswidth = spi_nor_get_protocol_addr_nbits(proto);

        if (op->dummy.nbytes)
                op->dummy.buswidth = spi_nor_get_protocol_addr_nbits(proto);

        if (op->data.nbytes)
                op->data.buswidth = spi_nor_get_protocol_data_nbits(proto);

        if (spi_nor_protocol_is_dtr(proto)) {
                /*
                 * SPIMEM supports mixed DTR modes, but right now we can only
                 * have all phases either DTR or STR. IOW, SPIMEM can have
                 * something like 4S-4D-4D, but SPI NOR can't. So, set all 4
                 * phases to either DTR or STR.
                 */
                op->cmd.dtr = true;
                op->addr.dtr = true;
                op->dummy.dtr = true;
                op->data.dtr = true;

                /* 2 bytes per clock cycle in DTR mode. */
                op->dummy.nbytes *= 2;

                ext = spi_nor_get_cmd_ext(nor, op);
                op->cmd.opcode = (op->cmd.opcode << 8) | ext;
                op->cmd.nbytes = 2;
        }
}

/**
 * spi_nor_spimem_bounce() - check if a bounce buffer is needed for the data
 *                           transfer
 * @nor:        pointer to 'struct spi_nor'
 * @op:         pointer to 'struct spi_mem_op' template for transfer
 *
 * If we have to use the bounce buffer, the data field in @op will be updated.
 *
 * Return: true if the bounce buffer is needed, false if not
 */
static bool spi_nor_spimem_bounce(struct spi_nor *nor, struct spi_mem_op *op)
{
        /* op->data.buf.in occupies the same memory as op->data.buf.out */
        if (object_is_on_stack(op->data.buf.in) ||
            !virt_addr_valid(op->data.buf.in)) {
                if (op->data.nbytes > nor->bouncebuf_size)
                        op->data.nbytes = nor->bouncebuf_size;
                op->data.buf.in = nor->bouncebuf;
                return true;
        }

        return false;
}

/**
 * spi_nor_spimem_exec_op() - execute a memory operation
 * @nor:        pointer to 'struct spi_nor'
 * @op:         pointer to 'struct spi_mem_op' template for transfer
 *
 * Return: 0 on success, -error otherwise.
 */
static int spi_nor_spimem_exec_op(struct spi_nor *nor, struct spi_mem_op *op)
{
        int error;

        error = spi_mem_adjust_op_size(nor->spimem, op);
        if (error)
                return error;

        return spi_mem_exec_op(nor->spimem, op);
}

int spi_nor_controller_ops_read_reg(struct spi_nor *nor, u8 opcode,
                                    u8 *buf, size_t len)
{
        if (spi_nor_protocol_is_dtr(nor->reg_proto))
                return -EOPNOTSUPP;

        return nor->controller_ops->read_reg(nor, opcode, buf, len);
}

int spi_nor_controller_ops_write_reg(struct spi_nor *nor, u8 opcode,
                                     const u8 *buf, size_t len)
{
        if (spi_nor_protocol_is_dtr(nor->reg_proto))
                return -EOPNOTSUPP;

        return nor->controller_ops->write_reg(nor, opcode, buf, len);
}

static int spi_nor_controller_ops_erase(struct spi_nor *nor, loff_t offs)
{
        if (spi_nor_protocol_is_dtr(nor->reg_proto))
                return -EOPNOTSUPP;

        return nor->controller_ops->erase(nor, offs);
}

/**
 * spi_nor_spimem_read_data() - read data from flash's memory region via
 *                              spi-mem
 * @nor:        pointer to 'struct spi_nor'
 * @from:       offset to read from
 * @len:        number of bytes to read
 * @buf:        pointer to dst buffer
 *
 * Return: number of bytes read successfully, -errno otherwise
 */
static ssize_t spi_nor_spimem_read_data(struct spi_nor *nor, loff_t from,
                                        size_t len, u8 *buf)
{
        struct spi_mem_op op =
                SPI_MEM_OP(SPI_MEM_OP_CMD(nor->read_opcode, 0),
                           SPI_MEM_OP_ADDR(nor->addr_nbytes, from, 0),
                           SPI_MEM_OP_DUMMY(nor->read_dummy, 0),
                           SPI_MEM_OP_DATA_IN(len, buf, 0));
        bool usebouncebuf;
        ssize_t nbytes;
        int error;

        spi_nor_spimem_setup_op(nor, &op, nor->read_proto);

        /* convert the dummy cycles to the number of bytes */
        op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
        if (spi_nor_protocol_is_dtr(nor->read_proto))
                op.dummy.nbytes *= 2;

        usebouncebuf = spi_nor_spimem_bounce(nor, &op);

        if (nor->dirmap.rdesc) {
                nbytes = spi_mem_dirmap_read(nor->dirmap.rdesc, op.addr.val,
                                             op.data.nbytes, op.data.buf.in);
        } else {
                error = spi_nor_spimem_exec_op(nor, &op);
                if (error)
                        return error;
                nbytes = op.data.nbytes;
        }

        if (usebouncebuf && nbytes > 0)
                memcpy(buf, op.data.buf.in, nbytes);

        return nbytes;
}

/**
 * spi_nor_read_data() - read data from flash memory
 * @nor:        pointer to 'struct spi_nor'
 * @from:       offset to read from
 * @len:        number of bytes to read
 * @buf:        pointer to dst buffer
 *
 * Return: number of bytes read successfully, -errno otherwise
 */
ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len, u8 *buf)
{
        if (nor->spimem)
                return spi_nor_spimem_read_data(nor, from, len, buf);

        return nor->controller_ops->read(nor, from, len, buf);
}

/**
 * spi_nor_spimem_write_data() - write data to flash memory via
 *                               spi-mem
 * @nor:        pointer to 'struct spi_nor'
 * @to:         offset to write to
 * @len:        number of bytes to write
 * @buf:        pointer to src buffer
 *
 * Return: number of bytes written successfully, -errno otherwise
 */
static ssize_t spi_nor_spimem_write_data(struct spi_nor *nor, loff_t to,
                                         size_t len, const u8 *buf)
{
        struct spi_mem_op op =
                SPI_MEM_OP(SPI_MEM_OP_CMD(nor->program_opcode, 0),
                           SPI_MEM_OP_ADDR(nor->addr_nbytes, to, 0),
                           SPI_MEM_OP_NO_DUMMY,
                           SPI_MEM_OP_DATA_OUT(len, buf, 0));
        ssize_t nbytes;
        int error;

        if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
                op.addr.nbytes = 0;

        spi_nor_spimem_setup_op(nor, &op, nor->write_proto);

        if (spi_nor_spimem_bounce(nor, &op))
                memcpy(nor->bouncebuf, buf, op.data.nbytes);

        if (nor->dirmap.wdesc) {
                nbytes = spi_mem_dirmap_write(nor->dirmap.wdesc, op.addr.val,
                                              op.data.nbytes, op.data.buf.out);
        } else {
                error = spi_nor_spimem_exec_op(nor, &op);
                if (error)
                        return error;
                nbytes = op.data.nbytes;
        }

        return nbytes;
}

/**
 * spi_nor_write_data() - write data to flash memory
 * @nor:        pointer to 'struct spi_nor'
 * @to:         offset to write to
 * @len:        number of bytes to write
 * @buf:        pointer to src buffer
 *
 * Return: number of bytes written successfully, -errno otherwise
 */
ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
                           const u8 *buf)
{
        if (nor->spimem)
                return spi_nor_spimem_write_data(nor, to, len, buf);

        return nor->controller_ops->write(nor, to, len, buf);
}

/**
 * spi_nor_read_any_reg() - read any register from flash memory, nonvolatile or
 * volatile.
 * @nor:        pointer to 'struct spi_nor'.
 * @op:         SPI memory operation. op->data.buf must be DMA-able.
 * @proto:      SPI protocol to use for the register operation.
 *
 * Return: zero on success, -errno otherwise
 */
int spi_nor_read_any_reg(struct spi_nor *nor, struct spi_mem_op *op,
                         enum spi_nor_protocol proto)
{
        if (!nor->spimem)
                return -EOPNOTSUPP;

        spi_nor_spimem_setup_op(nor, op, proto);
        return spi_nor_spimem_exec_op(nor, op);
}

/**
 * spi_nor_write_any_volatile_reg() - write any volatile register to flash
 * memory.
 * @nor:        pointer to 'struct spi_nor'
 * @op:         SPI memory operation. op->data.buf must be DMA-able.
 * @proto:      SPI protocol to use for the register operation.
 *
 * Writing volatile registers are instant according to some manufacturers
 * (Cypress, Micron) and do not need any status polling.
 *
 * Return: zero on success, -errno otherwise
 */
int spi_nor_write_any_volatile_reg(struct spi_nor *nor, struct spi_mem_op *op,
                                   enum spi_nor_protocol proto)
{
        int ret;

        if (!nor->spimem)
                return -EOPNOTSUPP;

        ret = spi_nor_write_enable(nor);
        if (ret)
                return ret;
        spi_nor_spimem_setup_op(nor, op, proto);
        return spi_nor_spimem_exec_op(nor, op);
}

/**
 * spi_nor_write_enable() - Set write enable latch with Write Enable command.
 * @nor:        pointer to 'struct spi_nor'.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_write_enable(struct spi_nor *nor)
{
        int ret;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_WREN_OP;

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_write_reg(nor, SPINOR_OP_WREN,
                                                       NULL, 0);
        }

        if (ret)
                dev_dbg(nor->dev, "error %d on Write Enable\n", ret);

        return ret;
}

/**
 * spi_nor_write_disable() - Send Write Disable instruction to the chip.
 * @nor:        pointer to 'struct spi_nor'.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_write_disable(struct spi_nor *nor)
{
        int ret;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_WRDI_OP;

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_write_reg(nor, SPINOR_OP_WRDI,
                                                       NULL, 0);
        }

        if (ret)
                dev_dbg(nor->dev, "error %d on Write Disable\n", ret);

        return ret;
}

/**
 * spi_nor_read_id() - Read the JEDEC ID.
 * @nor:        pointer to 'struct spi_nor'.
 * @naddr:      number of address bytes to send. Can be zero if the operation
 *              does not need to send an address.
 * @ndummy:     number of dummy bytes to send after an opcode or address. Can
 *              be zero if the operation does not require dummy bytes.
 * @id:         pointer to a DMA-able buffer where the value of the JEDEC ID
 *              will be written.
 * @proto:      the SPI protocol for register operation.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_read_id(struct spi_nor *nor, u8 naddr, u8 ndummy, u8 *id,
                    enum spi_nor_protocol proto)
{
        int ret;

        if (nor->spimem) {
                struct spi_mem_op op =
                        SPI_NOR_READID_OP(naddr, ndummy, id, SPI_NOR_MAX_ID_LEN);

                spi_nor_spimem_setup_op(nor, &op, proto);
                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDID, id,
                                                    SPI_NOR_MAX_ID_LEN);
        }
        return ret;
}

/**
 * spi_nor_read_sr() - Read the Status Register.
 * @nor:        pointer to 'struct spi_nor'.
 * @sr:         pointer to a DMA-able buffer where the value of the
 *              Status Register will be written. Should be at least 2 bytes.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
{
        int ret;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_RDSR_OP(sr);

                if (nor->reg_proto == SNOR_PROTO_8_8_8_DTR) {
                        op.addr.nbytes = nor->params->rdsr_addr_nbytes;
                        op.dummy.nbytes = nor->params->rdsr_dummy;
                        /*
                         * We don't want to read only one byte in DTR mode. So,
                         * read 2 and then discard the second byte.
                         */
                        op.data.nbytes = 2;
                }

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_read_reg(nor, SPINOR_OP_RDSR, sr,
                                                      1);
        }

        if (ret)
                dev_dbg(nor->dev, "error %d reading SR\n", ret);

        return ret;
}

/**
 * spi_nor_read_cr() - Read the Configuration Register using the
 * SPINOR_OP_RDCR (35h) command.
 * @nor:        pointer to 'struct spi_nor'
 * @cr:         pointer to a DMA-able buffer where the value of the
 *              Configuration Register will be written.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_read_cr(struct spi_nor *nor, u8 *cr)
{
        int ret;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_RDCR_OP(cr);

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_read_reg(nor, SPINOR_OP_RDCR, cr,
                                                      1);
        }

        if (ret)
                dev_dbg(nor->dev, "error %d reading CR\n", ret);

        return ret;
}

/**
 * spi_nor_set_4byte_addr_mode() - Enter/Exit 4-byte address mode.
 * @nor:        pointer to 'struct spi_nor'.
 * @enable:     true to enter the 4-byte address mode, false to exit the 4-byte
 *              address mode.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_set_4byte_addr_mode(struct spi_nor *nor, bool enable)
{
        int ret;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_EN4B_EX4B_OP(enable);

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_write_reg(nor,
                                                       enable ? SPINOR_OP_EN4B :
                                                                SPINOR_OP_EX4B,
                                                       NULL, 0);
        }

        if (ret)
                dev_dbg(nor->dev, "error %d setting 4-byte mode\n", ret);

        return ret;
}

/**
 * spansion_set_4byte_addr_mode() - Set 4-byte address mode for Spansion
 * flashes.
 * @nor:        pointer to 'struct spi_nor'.
 * @enable:     true to enter the 4-byte address mode, false to exit the 4-byte
 *              address mode.
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spansion_set_4byte_addr_mode(struct spi_nor *nor, bool enable)
{
        int ret;

        nor->bouncebuf[0] = enable << 7;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_BRWR_OP(nor->bouncebuf);

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_write_reg(nor, SPINOR_OP_BRWR,
                                                       nor->bouncebuf, 1);
        }

        if (ret)
                dev_dbg(nor->dev, "error %d setting 4-byte mode\n", ret);

        return ret;
}

/**
 * spi_nor_sr_ready() - Query the Status Register to see if the flash is ready
 * for new commands.
 * @nor:        pointer to 'struct spi_nor'.
 *
 * Return: 1 if ready, 0 if not ready, -errno on errors.
 */
int spi_nor_sr_ready(struct spi_nor *nor)
{
        int ret;

        ret = spi_nor_read_sr(nor, nor->bouncebuf);
        if (ret)
                return ret;

        return !(nor->bouncebuf[0] & SR_WIP);
}

/**
 * spi_nor_ready() - Query the flash to see if it is ready for new commands.
 * @nor:        pointer to 'struct spi_nor'.
 *
 * Return: 1 if ready, 0 if not ready, -errno on errors.
 */
static int spi_nor_ready(struct spi_nor *nor)
{
        /* Flashes might override the standard routine. */
        if (nor->params->ready)
                return nor->params->ready(nor);

        return spi_nor_sr_ready(nor);
}

/**
 * spi_nor_wait_till_ready_with_timeout() - Service routine to read the
 * Status Register until ready, or timeout occurs.
 * @nor:                pointer to "struct spi_nor".
 * @timeout_jiffies:    jiffies to wait until timeout.
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_wait_till_ready_with_timeout(struct spi_nor *nor,
                                                unsigned long timeout_jiffies)
{
        unsigned long deadline;
        int timeout = 0, ret;

        deadline = jiffies + timeout_jiffies;

        while (!timeout) {
                if (time_after_eq(jiffies, deadline))
                        timeout = 1;

                ret = spi_nor_ready(nor);
                if (ret < 0)
                        return ret;
                if (ret)
                        return 0;

                cond_resched();
        }

        dev_dbg(nor->dev, "flash operation timed out\n");

        return -ETIMEDOUT;
}

/**
 * spi_nor_wait_till_ready() - Wait for a predefined amount of time for the
 * flash to be ready, or timeout occurs.
 * @nor:        pointer to "struct spi_nor".
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_wait_till_ready(struct spi_nor *nor)
{
        return spi_nor_wait_till_ready_with_timeout(nor,
                                                    DEFAULT_READY_WAIT_JIFFIES);
}

/**
 * spi_nor_global_block_unlock() - Unlock Global Block Protection.
 * @nor:        pointer to 'struct spi_nor'.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_global_block_unlock(struct spi_nor *nor)
{
        int ret;

        ret = spi_nor_write_enable(nor);
        if (ret)
                return ret;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_GBULK_OP;

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_write_reg(nor, SPINOR_OP_GBULK,
                                                       NULL, 0);
        }

        if (ret) {
                dev_dbg(nor->dev, "error %d on Global Block Unlock\n", ret);
                return ret;
        }

        return spi_nor_wait_till_ready(nor);
}

/**
 * spi_nor_write_sr() - Write the Status Register.
 * @nor:        pointer to 'struct spi_nor'.
 * @sr:         pointer to DMA-able buffer to write to the Status Register.
 * @len:        number of bytes to write to the Status Register.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_write_sr(struct spi_nor *nor, const u8 *sr, size_t len)
{
        int ret;

        ret = spi_nor_write_enable(nor);
        if (ret)
                return ret;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_WRSR_OP(sr, len);

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_write_reg(nor, SPINOR_OP_WRSR, sr,
                                                       len);
        }

        if (ret) {
                dev_dbg(nor->dev, "error %d writing SR\n", ret);
                return ret;
        }

        return spi_nor_wait_till_ready(nor);
}

/**
 * spi_nor_write_sr1_and_check() - Write one byte to the Status Register 1 and
 * ensure that the byte written match the received value.
 * @nor:        pointer to a 'struct spi_nor'.
 * @sr1:        byte value to be written to the Status Register.
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_write_sr1_and_check(struct spi_nor *nor, u8 sr1)
{
        int ret;

        nor->bouncebuf[0] = sr1;

        ret = spi_nor_write_sr(nor, nor->bouncebuf, 1);
        if (ret)
                return ret;

        ret = spi_nor_read_sr(nor, nor->bouncebuf);
        if (ret)
                return ret;

        if (nor->bouncebuf[0] != sr1) {
                dev_dbg(nor->dev, "SR1: read back test failed\n");
                return -EIO;
        }

        return 0;
}

/**
 * spi_nor_write_16bit_sr_and_check() - Write the Status Register 1 and the
 * Status Register 2 in one shot. Ensure that the byte written in the Status
 * Register 1 match the received value, and that the 16-bit Write did not
 * affect what was already in the Status Register 2.
 * @nor:        pointer to a 'struct spi_nor'.
 * @sr1:        byte value to be written to the Status Register 1.
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_write_16bit_sr_and_check(struct spi_nor *nor, u8 sr1)
{
        int ret;
        u8 *sr_cr = nor->bouncebuf;
        u8 cr_written;

        /* Make sure we don't overwrite the contents of Status Register 2. */
        if (!(nor->flags & SNOR_F_NO_READ_CR)) {
                ret = spi_nor_read_cr(nor, &sr_cr[1]);
                if (ret)
                        return ret;
        } else if (nor->params->quad_enable) {
                /*
                 * If the Status Register 2 Read command (35h) is not
                 * supported, we should at least be sure we don't
                 * change the value of the SR2 Quad Enable bit.
                 *
                 * We can safely assume that when the Quad Enable method is
                 * set, the value of the QE bit is one, as a consequence of the
                 * nor->params->quad_enable() call.
                 *
                 * We can safely assume that the Quad Enable bit is present in
                 * the Status Register 2 at BIT(1). According to the JESD216
                 * revB standard, BFPT DWORDS[15], bits 22:20, the 16-bit
                 * Write Status (01h) command is available just for the cases
                 * in which the QE bit is described in SR2 at BIT(1).
                 */
                sr_cr[1] = SR2_QUAD_EN_BIT1;
        } else {
                sr_cr[1] = 0;
        }

        sr_cr[0] = sr1;

        ret = spi_nor_write_sr(nor, sr_cr, 2);
        if (ret)
                return ret;

        ret = spi_nor_read_sr(nor, sr_cr);
        if (ret)
                return ret;

        if (sr1 != sr_cr[0]) {
                dev_dbg(nor->dev, "SR: Read back test failed\n");
                return -EIO;
        }

        if (nor->flags & SNOR_F_NO_READ_CR)
                return 0;

        cr_written = sr_cr[1];

        ret = spi_nor_read_cr(nor, &sr_cr[1]);
        if (ret)
                return ret;

        if (cr_written != sr_cr[1]) {
                dev_dbg(nor->dev, "CR: read back test failed\n");
                return -EIO;
        }

        return 0;
}

/**
 * spi_nor_write_16bit_cr_and_check() - Write the Status Register 1 and the
 * Configuration Register in one shot. Ensure that the byte written in the
 * Configuration Register match the received value, and that the 16-bit Write
 * did not affect what was already in the Status Register 1.
 * @nor:        pointer to a 'struct spi_nor'.
 * @cr:         byte value to be written to the Configuration Register.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_write_16bit_cr_and_check(struct spi_nor *nor, u8 cr)
{
        int ret;
        u8 *sr_cr = nor->bouncebuf;
        u8 sr_written;

        /* Keep the current value of the Status Register 1. */
        ret = spi_nor_read_sr(nor, sr_cr);
        if (ret)
                return ret;

        sr_cr[1] = cr;

        ret = spi_nor_write_sr(nor, sr_cr, 2);
        if (ret)
                return ret;

        sr_written = sr_cr[0];

        ret = spi_nor_read_sr(nor, sr_cr);
        if (ret)
                return ret;

        if (sr_written != sr_cr[0]) {
                dev_dbg(nor->dev, "SR: Read back test failed\n");
                return -EIO;
        }

        if (nor->flags & SNOR_F_NO_READ_CR)
                return 0;

        ret = spi_nor_read_cr(nor, &sr_cr[1]);
        if (ret)
                return ret;

        if (cr != sr_cr[1]) {
                dev_dbg(nor->dev, "CR: read back test failed\n");
                return -EIO;
        }

        return 0;
}

/**
 * spi_nor_write_sr_and_check() - Write the Status Register 1 and ensure that
 * the byte written match the received value without affecting other bits in the
 * Status Register 1 and 2.
 * @nor:        pointer to a 'struct spi_nor'.
 * @sr1:        byte value to be written to the Status Register.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1)
{
        if (nor->flags & SNOR_F_HAS_16BIT_SR)
                return spi_nor_write_16bit_sr_and_check(nor, sr1);

        return spi_nor_write_sr1_and_check(nor, sr1);
}

/**
 * spi_nor_write_sr2() - Write the Status Register 2 using the
 * SPINOR_OP_WRSR2 (3eh) command.
 * @nor:        pointer to 'struct spi_nor'.
 * @sr2:        pointer to DMA-able buffer to write to the Status Register 2.
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_write_sr2(struct spi_nor *nor, const u8 *sr2)
{
        int ret;

        ret = spi_nor_write_enable(nor);
        if (ret)
                return ret;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_WRSR2_OP(sr2);

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_write_reg(nor, SPINOR_OP_WRSR2,
                                                       sr2, 1);
        }

        if (ret) {
                dev_dbg(nor->dev, "error %d writing SR2\n", ret);
                return ret;
        }

        return spi_nor_wait_till_ready(nor);
}

/**
 * spi_nor_read_sr2() - Read the Status Register 2 using the
 * SPINOR_OP_RDSR2 (3fh) command.
 * @nor:        pointer to 'struct spi_nor'.
 * @sr2:        pointer to DMA-able buffer where the value of the
 *              Status Register 2 will be written.
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_read_sr2(struct spi_nor *nor, u8 *sr2)
{
        int ret;

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_RDSR2_OP(sr2);

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_read_reg(nor, SPINOR_OP_RDSR2, sr2,
                                                      1);
        }

        if (ret)
                dev_dbg(nor->dev, "error %d reading SR2\n", ret);

        return ret;
}

/**
 * spi_nor_erase_chip() - Erase the entire flash memory.
 * @nor:        pointer to 'struct spi_nor'.
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_erase_chip(struct spi_nor *nor)
{
        int ret;

        dev_dbg(nor->dev, " %lldKiB\n", (long long)(nor->mtd.size >> 10));

        if (nor->spimem) {
                struct spi_mem_op op = SPI_NOR_CHIP_ERASE_OP;

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                ret = spi_mem_exec_op(nor->spimem, &op);
        } else {
                ret = spi_nor_controller_ops_write_reg(nor,
                                                       SPINOR_OP_CHIP_ERASE,
                                                       NULL, 0);
        }

        if (ret)
                dev_dbg(nor->dev, "error %d erasing chip\n", ret);

        return ret;
}

static u8 spi_nor_convert_opcode(u8 opcode, const u8 table[][2], size_t size)
{
        size_t i;

        for (i = 0; i < size; i++)
                if (table[i][0] == opcode)
                        return table[i][1];

        /* No conversion found, keep input op code. */
        return opcode;
}

u8 spi_nor_convert_3to4_read(u8 opcode)
{
        static const u8 spi_nor_3to4_read[][2] = {
                { SPINOR_OP_READ,       SPINOR_OP_READ_4B },
                { SPINOR_OP_READ_FAST,  SPINOR_OP_READ_FAST_4B },
                { SPINOR_OP_READ_1_1_2, SPINOR_OP_READ_1_1_2_4B },
                { SPINOR_OP_READ_1_2_2, SPINOR_OP_READ_1_2_2_4B },
                { SPINOR_OP_READ_1_1_4, SPINOR_OP_READ_1_1_4_4B },
                { SPINOR_OP_READ_1_4_4, SPINOR_OP_READ_1_4_4_4B },
                { SPINOR_OP_READ_1_1_8, SPINOR_OP_READ_1_1_8_4B },
                { SPINOR_OP_READ_1_8_8, SPINOR_OP_READ_1_8_8_4B },

                { SPINOR_OP_READ_1_1_1_DTR,     SPINOR_OP_READ_1_1_1_DTR_4B },
                { SPINOR_OP_READ_1_2_2_DTR,     SPINOR_OP_READ_1_2_2_DTR_4B },
                { SPINOR_OP_READ_1_4_4_DTR,     SPINOR_OP_READ_1_4_4_DTR_4B },
        };

        return spi_nor_convert_opcode(opcode, spi_nor_3to4_read,
                                      ARRAY_SIZE(spi_nor_3to4_read));
}

static u8 spi_nor_convert_3to4_program(u8 opcode)
{
        static const u8 spi_nor_3to4_program[][2] = {
                { SPINOR_OP_PP,         SPINOR_OP_PP_4B },
                { SPINOR_OP_PP_1_1_4,   SPINOR_OP_PP_1_1_4_4B },
                { SPINOR_OP_PP_1_4_4,   SPINOR_OP_PP_1_4_4_4B },
                { SPINOR_OP_PP_1_1_8,   SPINOR_OP_PP_1_1_8_4B },
                { SPINOR_OP_PP_1_8_8,   SPINOR_OP_PP_1_8_8_4B },
        };

        return spi_nor_convert_opcode(opcode, spi_nor_3to4_program,
                                      ARRAY_SIZE(spi_nor_3to4_program));
}

static u8 spi_nor_convert_3to4_erase(u8 opcode)
{
        static const u8 spi_nor_3to4_erase[][2] = {
                { SPINOR_OP_BE_4K,      SPINOR_OP_BE_4K_4B },
                { SPINOR_OP_BE_32K,     SPINOR_OP_BE_32K_4B },
                { SPINOR_OP_SE,         SPINOR_OP_SE_4B },
        };

        return spi_nor_convert_opcode(opcode, spi_nor_3to4_erase,
                                      ARRAY_SIZE(spi_nor_3to4_erase));
}

static bool spi_nor_has_uniform_erase(const struct spi_nor *nor)
{
        return !!nor->params->erase_map.uniform_erase_type;
}

static void spi_nor_set_4byte_opcodes(struct spi_nor *nor)
{
        nor->read_opcode = spi_nor_convert_3to4_read(nor->read_opcode);
        nor->program_opcode = spi_nor_convert_3to4_program(nor->program_opcode);
        nor->erase_opcode = spi_nor_convert_3to4_erase(nor->erase_opcode);

        if (!spi_nor_has_uniform_erase(nor)) {
                struct spi_nor_erase_map *map = &nor->params->erase_map;
                struct spi_nor_erase_type *erase;
                int i;

                for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++) {
                        erase = &map->erase_type[i];
                        erase->opcode =
                                spi_nor_convert_3to4_erase(erase->opcode);
                }
        }
}

int spi_nor_lock_and_prep(struct spi_nor *nor)
{
        int ret = 0;

        mutex_lock(&nor->lock);

        if (nor->controller_ops &&  nor->controller_ops->prepare) {
                ret = nor->controller_ops->prepare(nor);
                if (ret) {
                        mutex_unlock(&nor->lock);
                        return ret;
                }
        }
        return ret;
}

void spi_nor_unlock_and_unprep(struct spi_nor *nor)
{
        if (nor->controller_ops && nor->controller_ops->unprepare)
                nor->controller_ops->unprepare(nor);
        mutex_unlock(&nor->lock);
}

static u32 spi_nor_convert_addr(struct spi_nor *nor, loff_t addr)
{
        if (!nor->params->convert_addr)
                return addr;

        return nor->params->convert_addr(nor, addr);
}

/*
 * Initiate the erasure of a single sector
 */
int spi_nor_erase_sector(struct spi_nor *nor, u32 addr)
{
        int i;

        addr = spi_nor_convert_addr(nor, addr);

        if (nor->spimem) {
                struct spi_mem_op op =
                        SPI_NOR_SECTOR_ERASE_OP(nor->erase_opcode,
                                                nor->addr_nbytes, addr);

                spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

                return spi_mem_exec_op(nor->spimem, &op);
        } else if (nor->controller_ops->erase) {
                return spi_nor_controller_ops_erase(nor, addr);
        }

        /*
         * Default implementation, if driver doesn't have a specialized HW
         * control
         */
        for (i = nor->addr_nbytes - 1; i >= 0; i--) {
                nor->bouncebuf[i] = addr & 0xff;
                addr >>= 8;
        }

        return spi_nor_controller_ops_write_reg(nor, nor->erase_opcode,
                                                nor->bouncebuf, nor->addr_nbytes);
}

/**
 * spi_nor_div_by_erase_size() - calculate remainder and update new dividend
 * @erase:      pointer to a structure that describes a SPI NOR erase type
 * @dividend:   dividend value
 * @remainder:  pointer to u32 remainder (will be updated)
 *
 * Return: the result of the division
 */
static u64 spi_nor_div_by_erase_size(const struct spi_nor_erase_type *erase,
                                     u64 dividend, u32 *remainder)
{
        /* JEDEC JESD216B Standard imposes erase sizes to be power of 2. */
        *remainder = (u32)dividend & erase->size_mask;
        return dividend >> erase->size_shift;
}

/**
 * spi_nor_find_best_erase_type() - find the best erase type for the given
 *                                  offset in the serial flash memory and the
 *                                  number of bytes to erase. The region in
 *                                  which the address fits is expected to be
 *                                  provided.
 * @map:        the erase map of the SPI NOR
 * @region:     pointer to a structure that describes a SPI NOR erase region
 * @addr:       offset in the serial flash memory
 * @len:        number of bytes to erase
 *
 * Return: a pointer to the best fitted erase type, NULL otherwise.
 */
static const struct spi_nor_erase_type *
spi_nor_find_best_erase_type(const struct spi_nor_erase_map *map,
                             const struct spi_nor_erase_region *region,
                             u64 addr, u32 len)
{
        const struct spi_nor_erase_type *erase;
        u32 rem;
        int i;
        u8 erase_mask = region->offset & SNOR_ERASE_TYPE_MASK;

        /*
         * Erase types are ordered by size, with the smallest erase type at
         * index 0.
         */
        for (i = SNOR_ERASE_TYPE_MAX - 1; i >= 0; i--) {
                /* Does the erase region support the tested erase type? */
                if (!(erase_mask & BIT(i)))
                        continue;

                erase = &map->erase_type[i];
                if (!erase->size)
                        continue;

                /* Alignment is not mandatory for overlaid regions */
                if (region->offset & SNOR_OVERLAID_REGION &&
                    region->size <= len)
                        return erase;

                /* Don't erase more than what the user has asked for. */
                if (erase->size > len)
                        continue;

                spi_nor_div_by_erase_size(erase, addr, &rem);
                if (!rem)
                        return erase;
        }

        return NULL;
}

static u64 spi_nor_region_is_last(const struct spi_nor_erase_region *region)
{
        return region->offset & SNOR_LAST_REGION;
}

static u64 spi_nor_region_end(const struct spi_nor_erase_region *region)
{
        return (region->offset & ~SNOR_ERASE_FLAGS_MASK) + region->size;
}

/**
 * spi_nor_region_next() - get the next spi nor region
 * @region:     pointer to a structure that describes a SPI NOR erase region
 *
 * Return: the next spi nor region or NULL if last region.
 */
struct spi_nor_erase_region *
spi_nor_region_next(struct spi_nor_erase_region *region)
{
        if (spi_nor_region_is_last(region))
                return NULL;
        region++;
        return region;
}

/**
 * spi_nor_find_erase_region() - find the region of the serial flash memory in
 *                               which the offset fits
 * @map:        the erase map of the SPI NOR
 * @addr:       offset in the serial flash memory
 *
 * Return: a pointer to the spi_nor_erase_region struct, ERR_PTR(-errno)
 *         otherwise.
 */
static struct spi_nor_erase_region *
spi_nor_find_erase_region(const struct spi_nor_erase_map *map, u64 addr)
{
        struct spi_nor_erase_region *region = map->regions;
        u64 region_start = region->offset & ~SNOR_ERASE_FLAGS_MASK;
        u64 region_end = region_start + region->size;

        while (addr < region_start || addr >= region_end) {
                region = spi_nor_region_next(region);
                if (!region)
                        return ERR_PTR(-EINVAL);

                region_start = region->offset & ~SNOR_ERASE_FLAGS_MASK;
                region_end = region_start + region->size;
        }

        return region;
}

/**
 * spi_nor_init_erase_cmd() - initialize an erase command
 * @region:     pointer to a structure that describes a SPI NOR erase region
 * @erase:      pointer to a structure that describes a SPI NOR erase type
 *
 * Return: the pointer to the allocated erase command, ERR_PTR(-errno)
 *         otherwise.
 */
static struct spi_nor_erase_command *
spi_nor_init_erase_cmd(const struct spi_nor_erase_region *region,
                       const struct spi_nor_erase_type *erase)
{
        struct spi_nor_erase_command *cmd;

        cmd = kmalloc(sizeof(*cmd), GFP_KERNEL);
        if (!cmd)
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(&cmd->list);
        cmd->opcode = erase->opcode;
        cmd->count = 1;

        if (region->offset & SNOR_OVERLAID_REGION)
                cmd->size = region->size;
        else
                cmd->size = erase->size;

        return cmd;
}

/**
 * spi_nor_destroy_erase_cmd_list() - destroy erase command list
 * @erase_list: list of erase commands
 */
static void spi_nor_destroy_erase_cmd_list(struct list_head *erase_list)
{
        struct spi_nor_erase_command *cmd, *next;

        list_for_each_entry_safe(cmd, next, erase_list, list) {
                list_del(&cmd->list);
                kfree(cmd);
        }
}

/**
 * spi_nor_init_erase_cmd_list() - initialize erase command list
 * @nor:        pointer to a 'struct spi_nor'
 * @erase_list: list of erase commands to be executed once we validate that the
 *              erase can be performed
 * @addr:       offset in the serial flash memory
 * @len:        number of bytes to erase
 *
 * Builds the list of best fitted erase commands and verifies if the erase can
 * be performed.
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_init_erase_cmd_list(struct spi_nor *nor,
                                       struct list_head *erase_list,
                                       u64 addr, u32 len)
{
        const struct spi_nor_erase_map *map = &nor->params->erase_map;
        const struct spi_nor_erase_type *erase, *prev_erase = NULL;
        struct spi_nor_erase_region *region;
        struct spi_nor_erase_command *cmd = NULL;
        u64 region_end;
        int ret = -EINVAL;

        region = spi_nor_find_erase_region(map, addr);
        if (IS_ERR(region))
                return PTR_ERR(region);

        region_end = spi_nor_region_end(region);

        while (len) {
                erase = spi_nor_find_best_erase_type(map, region, addr, len);
                if (!erase)
                        goto destroy_erase_cmd_list;

                if (prev_erase != erase ||
                    erase->size != cmd->size ||
                    region->offset & SNOR_OVERLAID_REGION) {
                        cmd = spi_nor_init_erase_cmd(region, erase);
                        if (IS_ERR(cmd)) {
                                ret = PTR_ERR(cmd);
                                goto destroy_erase_cmd_list;
                        }

                        list_add_tail(&cmd->list, erase_list);
                } else {
                        cmd->count++;
                }

                addr += cmd->size;
                len -= cmd->size;

                if (len && addr >= region_end) {
                        region = spi_nor_region_next(region);
                        if (!region)
                                goto destroy_erase_cmd_list;
                        region_end = spi_nor_region_end(region);
                }

                prev_erase = erase;
        }

        return 0;

destroy_erase_cmd_list:
        spi_nor_destroy_erase_cmd_list(erase_list);
        return ret;
}

/**
 * spi_nor_erase_multi_sectors() - perform a non-uniform erase
 * @nor:        pointer to a 'struct spi_nor'
 * @addr:       offset in the serial flash memory
 * @len:        number of bytes to erase
 *
 * Build a list of best fitted erase commands and execute it once we validate
 * that the erase can be performed.
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_erase_multi_sectors(struct spi_nor *nor, u64 addr, u32 len)
{
        LIST_HEAD(erase_list);
        struct spi_nor_erase_command *cmd, *next;
        int ret;

        ret = spi_nor_init_erase_cmd_list(nor, &erase_list, addr, len);
        if (ret)
                return ret;

        list_for_each_entry_safe(cmd, next, &erase_list, list) {
                nor->erase_opcode = cmd->opcode;
                while (cmd->count) {
                        dev_vdbg(nor->dev, "erase_cmd->size = 0x%08x, erase_cmd->opcode = 0x%02x, erase_cmd->count = %u\n",
                                 cmd->size, cmd->opcode, cmd->count);

                        ret = spi_nor_write_enable(nor);
                        if (ret)
                                goto destroy_erase_cmd_list;

                        ret = spi_nor_erase_sector(nor, addr);
                        if (ret)
                                goto destroy_erase_cmd_list;

                        ret = spi_nor_wait_till_ready(nor);
                        if (ret)
                                goto destroy_erase_cmd_list;

                        addr += cmd->size;
                        cmd->count--;
                }
                list_del(&cmd->list);
                kfree(cmd);
        }

        return 0;

destroy_erase_cmd_list:
        spi_nor_destroy_erase_cmd_list(&erase_list);
        return ret;
}

/*
 * Erase an address range on the nor chip.  The address range may extend
 * one or more erase sectors. Return an error if there is a problem erasing.
 */
static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
{
        struct spi_nor *nor = mtd_to_spi_nor(mtd);
        u32 addr, len;
        uint32_t rem;
        int ret;

        dev_dbg(nor->dev, "at 0x%llx, len %lld\n", (long long)instr->addr,
                        (long long)instr->len);

        if (spi_nor_has_uniform_erase(nor)) {
                div_u64_rem(instr->len, mtd->erasesize, &rem);
                if (rem)
                        return -EINVAL;
        }

        addr = instr->addr;
        len = instr->len;

        ret = spi_nor_lock_and_prep(nor);
        if (ret)
                return ret;

        /* whole-chip erase? */
        if (len == mtd->size && !(nor->flags & SNOR_F_NO_OP_CHIP_ERASE)) {
                unsigned long timeout;

                ret = spi_nor_write_enable(nor);
                if (ret)
                        goto erase_err;

                ret = spi_nor_erase_chip(nor);
                if (ret)
                        goto erase_err;

                /*
                 * Scale the timeout linearly with the size of the flash, with
                 * a minimum calibrated to an old 2MB flash. We could try to
                 * pull these from CFI/SFDP, but these values should be good
                 * enough for now.
                 */
                timeout = max(CHIP_ERASE_2MB_READY_WAIT_JIFFIES,
                              CHIP_ERASE_2MB_READY_WAIT_JIFFIES *
                              (unsigned long)(mtd->size / SZ_2M));
                ret = spi_nor_wait_till_ready_with_timeout(nor, timeout);
                if (ret)
                        goto erase_err;

        /* REVISIT in some cases we could speed up erasing large regions
         * by using SPINOR_OP_SE instead of SPINOR_OP_BE_4K.  We may have set up
         * to use "small sector erase", but that's not always optimal.
         */

        /* "sector"-at-a-time erase */
        } else if (spi_nor_has_uniform_erase(nor)) {
                while (len) {
                        ret = spi_nor_write_enable(nor);
                        if (ret)
                                goto erase_err;

                        ret = spi_nor_erase_sector(nor, addr);
                        if (ret)
                                goto erase_err;

                        ret = spi_nor_wait_till_ready(nor);
                        if (ret)
                                goto erase_err;

                        addr += mtd->erasesize;
                        len -= mtd->erasesize;
                }

        /* erase multiple sectors */
        } else {
                ret = spi_nor_erase_multi_sectors(nor, addr, len);
                if (ret)
                        goto erase_err;
        }

        ret = spi_nor_write_disable(nor);

erase_err:
        spi_nor_unlock_and_unprep(nor);

        return ret;
}

/**
 * spi_nor_sr1_bit6_quad_enable() - Set the Quad Enable BIT(6) in the Status
 * Register 1.
 * @nor:        pointer to a 'struct spi_nor'
 *
 * Bit 6 of the Status Register 1 is the QE bit for Macronix like QSPI memories.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor)
{
        int ret;

        ret = spi_nor_read_sr(nor, nor->bouncebuf);
        if (ret)
                return ret;

        if (nor->bouncebuf[0] & SR1_QUAD_EN_BIT6)
                return 0;

        nor->bouncebuf[0] |= SR1_QUAD_EN_BIT6;

        return spi_nor_write_sr1_and_check(nor, nor->bouncebuf[0]);
}

/**
 * spi_nor_sr2_bit1_quad_enable() - set the Quad Enable BIT(1) in the Status
 * Register 2.
 * @nor:       pointer to a 'struct spi_nor'.
 *
 * Bit 1 of the Status Register 2 is the QE bit for Spansion like QSPI memories.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor)
{
        int ret;

        if (nor->flags & SNOR_F_NO_READ_CR)
                return spi_nor_write_16bit_cr_and_check(nor, SR2_QUAD_EN_BIT1);

        ret = spi_nor_read_cr(nor, nor->bouncebuf);
        if (ret)
                return ret;

        if (nor->bouncebuf[0] & SR2_QUAD_EN_BIT1)
                return 0;

        nor->bouncebuf[0] |= SR2_QUAD_EN_BIT1;

        return spi_nor_write_16bit_cr_and_check(nor, nor->bouncebuf[0]);
}

/**
 * spi_nor_sr2_bit7_quad_enable() - set QE bit in Status Register 2.
 * @nor:        pointer to a 'struct spi_nor'
 *
 * Set the Quad Enable (QE) bit in the Status Register 2.
 *
 * This is one of the procedures to set the QE bit described in the SFDP
 * (JESD216 rev B) specification but no manufacturer using this procedure has
 * been identified yet, hence the name of the function.
 *
 * Return: 0 on success, -errno otherwise.
 */
int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor)
{
        u8 *sr2 = nor->bouncebuf;
        int ret;
        u8 sr2_written;

        /* Check current Quad Enable bit value. */
        ret = spi_nor_read_sr2(nor, sr2);
        if (ret)
                return ret;
        if (*sr2 & SR2_QUAD_EN_BIT7)
                return 0;

        /* Update the Quad Enable bit. */
        *sr2 |= SR2_QUAD_EN_BIT7;

        ret = spi_nor_write_sr2(nor, sr2);
        if (ret)
                return ret;

        sr2_written = *sr2;

        /* Read back and check it. */
        ret = spi_nor_read_sr2(nor, sr2);
        if (ret)
                return ret;

        if (*sr2 != sr2_written) {
                dev_dbg(nor->dev, "SR2: Read back test failed\n");
                return -EIO;
        }

        return 0;
}

static const struct spi_nor_manufacturer *manufacturers[] = {
        &spi_nor_atmel,
        &spi_nor_catalyst,
        &spi_nor_eon,
        &spi_nor_esmt,
        &spi_nor_everspin,
        &spi_nor_fujitsu,
        &spi_nor_gigadevice,
        &spi_nor_intel,
        &spi_nor_issi,
        &spi_nor_macronix,
        &spi_nor_micron,
        &spi_nor_st,
        &spi_nor_spansion,
        &spi_nor_sst,
        &spi_nor_winbond,
        &spi_nor_xilinx,
        &spi_nor_xmc,
};

static const struct flash_info spi_nor_generic_flash = {
        .name = "spi-nor-generic",
        /*
         * JESD216 rev A doesn't specify the page size, therefore we need a
         * sane default.
         */
        .page_size = 256,
        .parse_sfdp = true,
};

static const struct flash_info *spi_nor_match_id(struct spi_nor *nor,
                                                 const u8 *id)
{
        const struct flash_info *part;
        unsigned int i, j;

        for (i = 0; i < ARRAY_SIZE(manufacturers); i++) {
                for (j = 0; j < manufacturers[i]->nparts; j++) {
                        part = &manufacturers[i]->parts[j];
                        if (part->id_len &&
                            !memcmp(part->id, id, part->id_len)) {
                                nor->manufacturer = manufacturers[i];
                                return part;
                        }
                }
        }

        return NULL;
}

static const struct flash_info *spi_nor_detect(struct spi_nor *nor)
{
        const struct flash_info *info;
        u8 *id = nor->bouncebuf;
        int ret;

        ret = spi_nor_read_id(nor, 0, 0, id, nor->reg_proto);
        if (ret) {
                dev_dbg(nor->dev, "error %d reading JEDEC ID\n", ret);
                return ERR_PTR(ret);
        }

        /* Cache the complete flash ID. */
        nor->id = devm_kmemdup(nor->dev, id, SPI_NOR_MAX_ID_LEN, GFP_KERNEL);
        if (!nor->id)
                return ERR_PTR(-ENOMEM);

        info = spi_nor_match_id(nor, id);

        /* Fallback to a generic flash described only by its SFDP data. */
        if (!info) {
                ret = spi_nor_check_sfdp_signature(nor);
                if (!ret)
                        info = &spi_nor_generic_flash;
        }

        if (!info) {
                dev_err(nor->dev, "unrecognized JEDEC id bytes: %*ph\n",
                        SPI_NOR_MAX_ID_LEN, id);
                return ERR_PTR(-ENODEV);
        }
        return info;
}

static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
                        size_t *retlen, u_char *buf)
{
        struct spi_nor *nor = mtd_to_spi_nor(mtd);
        ssize_t ret;

        dev_dbg(nor->dev, "from 0x%08x, len %zd\n", (u32)from, len);

        ret = spi_nor_lock_and_prep(nor);
        if (ret)
                return ret;

        while (len) {
                loff_t addr = from;

                addr = spi_nor_convert_addr(nor, addr);

                ret = spi_nor_read_data(nor, addr, len, buf);
                if (ret == 0) {
                        /* We shouldn't see 0-length reads */
                        ret = -EIO;
                        goto read_err;
                }
                if (ret < 0)
                        goto read_err;

                WARN_ON(ret > len);
                *retlen += ret;
                buf += ret;
                from += ret;
                len -= ret;
        }
        ret = 0;

read_err:
        spi_nor_unlock_and_unprep(nor);
        return ret;
}

/*
 * Write an address range to the nor chip.  Data must be written in
 * FLASH_PAGESIZE chunks.  The address range may be any size provided
 * it is within the physical boundaries.
 */
static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
        size_t *retlen, const u_char *buf)
{
        struct spi_nor *nor = mtd_to_spi_nor(mtd);
        size_t page_offset, page_remain, i;
        ssize_t ret;
        u32 page_size = nor->params->page_size;

        dev_dbg(nor->dev, "to 0x%08x, len %zd\n", (u32)to, len);

        ret = spi_nor_lock_and_prep(nor);
        if (ret)
                return ret;

        for (i = 0; i < len; ) {
                ssize_t written;
                loff_t addr = to + i;

                /*
                 * If page_size is a power of two, the offset can be quickly
                 * calculated with an AND operation. On the other cases we
                 * need to do a modulus operation (more expensive).
                 */
                if (is_power_of_2(page_size)) {
                        page_offset = addr & (page_size - 1);
                } else {
                        uint64_t aux = addr;

                        page_offset = do_div(aux, page_size);
                }
                /* the size of data remaining on the first page */
                page_remain = min_t(size_t, page_size - page_offset, len - i);

                addr = spi_nor_convert_addr(nor, addr);

                ret = spi_nor_write_enable(nor);
                if (ret)
                        goto write_err;

                ret = spi_nor_write_data(nor, addr, page_remain, buf + i);
                if (ret < 0)
                        goto write_err;
                written = ret;

                ret = spi_nor_wait_till_ready(nor);
                if (ret)
                        goto write_err;
                *retlen += written;
                i += written;
        }

write_err:
        spi_nor_unlock_and_unprep(nor);
        return ret;
}

static int spi_nor_check(struct spi_nor *nor)
{
        if (!nor->dev ||
            (!nor->spimem && !nor->controller_ops) ||
            (!nor->spimem && nor->controller_ops &&
            (!nor->controller_ops->read ||
             !nor->controller_ops->write ||
             !nor->controller_ops->read_reg ||
             !nor->controller_ops->write_reg))) {
                pr_err("spi-nor: please fill all the necessary fields!\n");
                return -EINVAL;
        }

        if (nor->spimem && nor->controller_ops) {
                dev_err(nor->dev, "nor->spimem and nor->controller_ops are mutually exclusive, please set just one of them.\n");
                return -EINVAL;
        }

        return 0;
}

void
spi_nor_set_read_settings(struct spi_nor_read_command *read,
                          u8 num_mode_clocks,
                          u8 num_wait_states,
                          u8 opcode,
                          enum spi_nor_protocol proto)
{
        read->num_mode_clocks = num_mode_clocks;
        read->num_wait_states = num_wait_states;
        read->opcode = opcode;
        read->proto = proto;
}

void spi_nor_set_pp_settings(struct spi_nor_pp_command *pp, u8 opcode,
                             enum spi_nor_protocol proto)
{
        pp->opcode = opcode;
        pp->proto = proto;
}

static int spi_nor_hwcaps2cmd(u32 hwcaps, const int table[][2], size_t size)
{
        size_t i;

        for (i = 0; i < size; i++)
                if (table[i][0] == (int)hwcaps)
                        return table[i][1];

        return -EINVAL;
}

int spi_nor_hwcaps_read2cmd(u32 hwcaps)
{
        static const int hwcaps_read2cmd[][2] = {
                { SNOR_HWCAPS_READ,             SNOR_CMD_READ },
                { SNOR_HWCAPS_READ_FAST,        SNOR_CMD_READ_FAST },
                { SNOR_HWCAPS_READ_1_1_1_DTR,   SNOR_CMD_READ_1_1_1_DTR },
                { SNOR_HWCAPS_READ_1_1_2,       SNOR_CMD_READ_1_1_2 },
                { SNOR_HWCAPS_READ_1_2_2,       SNOR_CMD_READ_1_2_2 },
                { SNOR_HWCAPS_READ_2_2_2,       SNOR_CMD_READ_2_2_2 },
                { SNOR_HWCAPS_READ_1_2_2_DTR,   SNOR_CMD_READ_1_2_2_DTR },
                { SNOR_HWCAPS_READ_1_1_4,       SNOR_CMD_READ_1_1_4 },
                { SNOR_HWCAPS_READ_1_4_4,       SNOR_CMD_READ_1_4_4 },
                { SNOR_HWCAPS_READ_4_4_4,       SNOR_CMD_READ_4_4_4 },
                { SNOR_HWCAPS_READ_1_4_4_DTR,   SNOR_CMD_READ_1_4_4_DTR },
                { SNOR_HWCAPS_READ_1_1_8,       SNOR_CMD_READ_1_1_8 },
                { SNOR_HWCAPS_READ_1_8_8,       SNOR_CMD_READ_1_8_8 },
                { SNOR_HWCAPS_READ_8_8_8,       SNOR_CMD_READ_8_8_8 },
                { SNOR_HWCAPS_READ_1_8_8_DTR,   SNOR_CMD_READ_1_8_8_DTR },
                { SNOR_HWCAPS_READ_8_8_8_DTR,   SNOR_CMD_READ_8_8_8_DTR },
        };

        return spi_nor_hwcaps2cmd(hwcaps, hwcaps_read2cmd,
                                  ARRAY_SIZE(hwcaps_read2cmd));
}

int spi_nor_hwcaps_pp2cmd(u32 hwcaps)
{
        static const int hwcaps_pp2cmd[][2] = {
                { SNOR_HWCAPS_PP,               SNOR_CMD_PP },
                { SNOR_HWCAPS_PP_1_1_4,         SNOR_CMD_PP_1_1_4 },
                { SNOR_HWCAPS_PP_1_4_4,         SNOR_CMD_PP_1_4_4 },
                { SNOR_HWCAPS_PP_4_4_4,         SNOR_CMD_PP_4_4_4 },
                { SNOR_HWCAPS_PP_1_1_8,         SNOR_CMD_PP_1_1_8 },
                { SNOR_HWCAPS_PP_1_8_8,         SNOR_CMD_PP_1_8_8 },
                { SNOR_HWCAPS_PP_8_8_8,         SNOR_CMD_PP_8_8_8 },
                { SNOR_HWCAPS_PP_8_8_8_DTR,     SNOR_CMD_PP_8_8_8_DTR },
        };

        return spi_nor_hwcaps2cmd(hwcaps, hwcaps_pp2cmd,
                                  ARRAY_SIZE(hwcaps_pp2cmd));
}

/**
 * spi_nor_spimem_check_op - check if the operation is supported
 *                           by controller
 *@nor:        pointer to a 'struct spi_nor'
 *@op:         pointer to op template to be checked
 *
 * Returns 0 if operation is supported, -EOPNOTSUPP otherwise.
 */
static int spi_nor_spimem_check_op(struct spi_nor *nor,
                                   struct spi_mem_op *op)
{
        /*
         * First test with 4 address bytes. The opcode itself might
         * be a 3B addressing opcode but we don't care, because
         * SPI controller implementation should not check the opcode,
         * but just the sequence.
         */
        op->addr.nbytes = 4;
        if (!spi_mem_supports_op(nor->spimem, op)) {
                if (nor->params->size > SZ_16M)
                        return -EOPNOTSUPP;

                /* If flash size <= 16MB, 3 address bytes are sufficient */
                op->addr.nbytes = 3;
                if (!spi_mem_supports_op(nor->spimem, op))
                        return -EOPNOTSUPP;
        }

        return 0;
}

/**
 * spi_nor_spimem_check_readop - check if the read op is supported
 *                               by controller
 *@nor:         pointer to a 'struct spi_nor'
 *@read:        pointer to op template to be checked
 *
 * Returns 0 if operation is supported, -EOPNOTSUPP otherwise.
 */
static int spi_nor_spimem_check_readop(struct spi_nor *nor,
                                       const struct spi_nor_read_command *read)
{
        struct spi_mem_op op = SPI_NOR_READ_OP(read->opcode);

        spi_nor_spimem_setup_op(nor, &op, read->proto);

        /* convert the dummy cycles to the number of bytes */
        op.dummy.nbytes = (read->num_mode_clocks + read->num_wait_states) *
                          op.dummy.buswidth / 8;
        if (spi_nor_protocol_is_dtr(nor->read_proto))
                op.dummy.nbytes *= 2;

        return spi_nor_spimem_check_op(nor, &op);
}

/**
 * spi_nor_spimem_check_pp - check if the page program op is supported
 *                           by controller
 *@nor:         pointer to a 'struct spi_nor'
 *@pp:          pointer to op template to be checked
 *
 * Returns 0 if operation is supported, -EOPNOTSUPP otherwise.
 */
static int spi_nor_spimem_check_pp(struct spi_nor *nor,
                                   const struct spi_nor_pp_command *pp)
{
        struct spi_mem_op op = SPI_NOR_PP_OP(pp->opcode);

        spi_nor_spimem_setup_op(nor, &op, pp->proto);

        return spi_nor_spimem_check_op(nor, &op);
}

/**
 * spi_nor_spimem_adjust_hwcaps - Find optimal Read/Write protocol
 *                                based on SPI controller capabilities
 * @nor:        pointer to a 'struct spi_nor'
 * @hwcaps:     pointer to resulting capabilities after adjusting
 *              according to controller and flash's capability
 */
static void
spi_nor_spimem_adjust_hwcaps(struct spi_nor *nor, u32 *hwcaps)
{
        struct spi_nor_flash_parameter *params = nor->params;
        unsigned int cap;

        /* X-X-X modes are not supported yet, mask them all. */
        *hwcaps &= ~SNOR_HWCAPS_X_X_X;

        /*
         * If the reset line is broken, we do not want to enter a stateful
         * mode.
         */
        if (nor->flags & SNOR_F_BROKEN_RESET)
                *hwcaps &= ~(SNOR_HWCAPS_X_X_X | SNOR_HWCAPS_X_X_X_DTR);

        for (cap = 0; cap < sizeof(*hwcaps) * BITS_PER_BYTE; cap++) {
                int rdidx, ppidx;

                if (!(*hwcaps & BIT(cap)))
                        continue;

                rdidx = spi_nor_hwcaps_read2cmd(BIT(cap));
                if (rdidx >= 0 &&
                    spi_nor_spimem_check_readop(nor, &params->reads[rdidx]))
                        *hwcaps &= ~BIT(cap);

                ppidx = spi_nor_hwcaps_pp2cmd(BIT(cap));
                if (ppidx < 0)
                        continue;

                if (spi_nor_spimem_check_pp(nor,
                                            &params->page_programs[ppidx]))
                        *hwcaps &= ~BIT(cap);
        }
}

/**
 * spi_nor_set_erase_type() - set a SPI NOR erase type
 * @erase:      pointer to a structure that describes a SPI NOR erase type
 * @size:       the size of the sector/block erased by the erase type
 * @opcode:     the SPI command op code to erase the sector/block
 */
void spi_nor_set_erase_type(struct spi_nor_erase_type *erase, u32 size,
                            u8 opcode)
{
        erase->size = size;
        erase->opcode = opcode;
        /* JEDEC JESD216B Standard imposes erase sizes to be power of 2. */
        erase->size_shift = ffs(erase->size) - 1;
        erase->size_mask = (1 << erase->size_shift) - 1;
}

/**
 * spi_nor_mask_erase_type() - mask out a SPI NOR erase type
 * @erase:      pointer to a structure that describes a SPI NOR erase type
 */
void spi_nor_mask_erase_type(struct spi_nor_erase_type *erase)
{
        erase->size = 0;
}

/**
 * spi_nor_init_uniform_erase_map() - Initialize uniform erase map
 * @map:                the erase map of the SPI NOR
 * @erase_mask:         bitmask encoding erase types that can erase the entire
 *                      flash memory
 * @flash_size:         the spi nor flash memory size
 */
void spi_nor_init_uniform_erase_map(struct spi_nor_erase_map *map,
                                    u8 erase_mask, u64 flash_size)
{
        /* Offset 0 with erase_mask and SNOR_LAST_REGION bit set */
        map->uniform_region.offset = (erase_mask & SNOR_ERASE_TYPE_MASK) |
                                     SNOR_LAST_REGION;
        map->uniform_region.size = flash_size;
        map->regions = &map->uniform_region;
        map->uniform_erase_type = erase_mask;
}

int spi_nor_post_bfpt_fixups(struct spi_nor *nor,
                             const struct sfdp_parameter_header *bfpt_header,
                             const struct sfdp_bfpt *bfpt)
{
        int ret;

        if (nor->manufacturer && nor->manufacturer->fixups &&
            nor->manufacturer->fixups->post_bfpt) {
                ret = nor->manufacturer->fixups->post_bfpt(nor, bfpt_header,
                                                           bfpt);
                if (ret)
                        return ret;
        }

        if (nor->info->fixups && nor->info->fixups->post_bfpt)
                return nor->info->fixups->post_bfpt(nor, bfpt_header, bfpt);

        return 0;
}

static int spi_nor_select_read(struct spi_nor *nor,
                               u32 shared_hwcaps)
{
        int cmd, best_match = fls(shared_hwcaps & SNOR_HWCAPS_READ_MASK) - 1;
        const struct spi_nor_read_command *read;

        if (best_match < 0)
                return -EINVAL;

        cmd = spi_nor_hwcaps_read2cmd(BIT(best_match));
        if (cmd < 0)
                return -EINVAL;

        read = &nor->params->reads[cmd];
        nor->read_opcode = read->opcode;
        nor->read_proto = read->proto;

        /*
         * In the SPI NOR framework, we don't need to make the difference
         * between mode clock cycles and wait state clock cycles.
         * Indeed, the value of the mode clock cycles is used by a QSPI
         * flash memory to know whether it should enter or leave its 0-4-4
         * (Continuous Read / XIP) mode.
         * eXecution In Place is out of the scope of the mtd sub-system.
         * Hence we choose to merge both mode and wait state clock cycles
         * into the so called dummy clock cycles.
         */
        nor->read_dummy = read->num_mode_clocks + read->num_wait_states;
        return 0;
}

static int spi_nor_select_pp(struct spi_nor *nor,
                             u32 shared_hwcaps)
{
        int cmd, best_match = fls(shared_hwcaps & SNOR_HWCAPS_PP_MASK) - 1;
        const struct spi_nor_pp_command *pp;

        if (best_match < 0)
                return -EINVAL;

        cmd = spi_nor_hwcaps_pp2cmd(BIT(best_match));
        if (cmd < 0)
                return -EINVAL;

        pp = &nor->params->page_programs[cmd];
        nor->program_opcode = pp->opcode;
        nor->write_proto = pp->proto;
        return 0;
}

/**
 * spi_nor_select_uniform_erase() - select optimum uniform erase type
 * @map:                the erase map of the SPI NOR
 * @wanted_size:        the erase type size to search for. Contains the value of
 *                      info->sector_size, the "small sector" size in case
 *                      CONFIG_MTD_SPI_NOR_USE_4K_SECTORS is defined or 0 if
 *                      there is no information about the sector size. The
 *                      latter is the case if the flash parameters are parsed
 *                      solely by SFDP, then the largest supported erase type
 *                      is selected.
 *
 * Once the optimum uniform sector erase command is found, disable all the
 * other.
 *
 * Return: pointer to erase type on success, NULL otherwise.
 */
static const struct spi_nor_erase_type *
spi_nor_select_uniform_erase(struct spi_nor_erase_map *map,
                             const u32 wanted_size)
{
        const struct spi_nor_erase_type *tested_erase, *erase = NULL;
        int i;
        u8 uniform_erase_type = map->uniform_erase_type;

        for (i = SNOR_ERASE_TYPE_MAX - 1; i >= 0; i--) {
                if (!(uniform_erase_type & BIT(i)))
                        continue;

                tested_erase = &map->erase_type[i];

                /* Skip masked erase types. */
                if (!tested_erase->size)
                        continue;

                /*
                 * If the current erase size is the one, stop here:
                 * we have found the right uniform Sector Erase command.
                 */
                if (tested_erase->size == wanted_size) {
                        erase = tested_erase;
                        break;
                }

                /*
                 * Otherwise, the current erase size is still a valid candidate.
                 * Select the biggest valid candidate.
                 */
                if (!erase && tested_erase->size)
                        erase = tested_erase;
                        /* keep iterating to find the wanted_size */
        }

        if (!erase)
                return NULL;

        /* Disable all other Sector Erase commands. */
        map->uniform_erase_type &= ~SNOR_ERASE_TYPE_MASK;
        map->uniform_erase_type |= BIT(erase - map->erase_type);
        return erase;
}

static int spi_nor_select_erase(struct spi_nor *nor)
{
        struct spi_nor_erase_map *map = &nor->params->erase_map;
        const struct spi_nor_erase_type *erase = NULL;
        struct mtd_info *mtd = &nor->mtd;
        u32 wanted_size = nor->info->sector_size;
        int i;

        /*
         * The previous implementation handling Sector Erase commands assumed
         * that the SPI flash memory has an uniform layout then used only one
         * of the supported erase sizes for all Sector Erase commands.
         * So to be backward compatible, the new implementation also tries to
         * manage the SPI flash memory as uniform with a single erase sector
         * size, when possible.
         */
#ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
        /* prefer "small sector" erase if possible */
        wanted_size = 4096u;
#endif

        if (spi_nor_has_uniform_erase(nor)) {
                erase = spi_nor_select_uniform_erase(map, wanted_size);
                if (!erase)
                        return -EINVAL;
                nor->erase_opcode = erase->opcode;
                mtd->erasesize = erase->size;
                return 0;
        }

        /*
         * For non-uniform SPI flash memory, set mtd->erasesize to the
         * maximum erase sector size. No need to set nor->erase_opcode.
         */
        for (i = SNOR_ERASE_TYPE_MAX - 1; i >= 0; i--) {
                if (map->erase_type[i].size) {
                        erase = &map->erase_type[i];
                        break;
                }
        }

        if (!erase)
                return -EINVAL;

        mtd->erasesize = erase->size;
        return 0;
}

static int spi_nor_default_setup(struct spi_nor *nor,
                                 const struct spi_nor_hwcaps *hwcaps)
{
        struct spi_nor_flash_parameter *params = nor->params;
        u32 ignored_mask, shared_mask;
        int err;

        /*
         * Keep only the hardware capabilities supported by both the SPI
         * controller and the SPI flash memory.
         */
        shared_mask = hwcaps->mask & params->hwcaps.mask;

        if (nor->spimem) {
                /*
                 * When called from spi_nor_probe(), all caps are set and we
                 * need to discard some of them based on what the SPI
                 * controller actually supports (using spi_mem_supports_op()).
                 */
                spi_nor_spimem_adjust_hwcaps(nor, &shared_mask);
        } else {
                /*
                 * SPI n-n-n protocols are not supported when the SPI
                 * controller directly implements the spi_nor interface.
                 * Yet another reason to switch to spi-mem.
                 */
                ignored_mask = SNOR_HWCAPS_X_X_X | SNOR_HWCAPS_X_X_X_DTR;
                if (shared_mask & ignored_mask) {
                        dev_dbg(nor->dev,
                                "SPI n-n-n protocols are not supported.\n");
                        shared_mask &= ~ignored_mask;
                }
        }

        /* Select the (Fast) Read command. */
        err = spi_nor_select_read(nor, shared_mask);
        if (err) {
                dev_dbg(nor->dev,
                        "can't select read settings supported by both the SPI controller and memory.\n");
                return err;
        }

        /* Select the Page Program command. */
        err = spi_nor_select_pp(nor, shared_mask);
        if (err) {
                dev_dbg(nor->dev,
                        "can't select write settings supported by both the SPI controller and memory.\n");
                return err;
        }

        /* Select the Sector Erase command. */
        err = spi_nor_select_erase(nor);
        if (err) {
                dev_dbg(nor->dev,
                        "can't select erase settings supported by both the SPI controller and memory.\n");
                return err;
        }

        return 0;
}

static int spi_nor_set_addr_nbytes(struct spi_nor *nor)
{
        if (nor->params->addr_nbytes) {
                nor->addr_nbytes = nor->params->addr_nbytes;
        } else if (nor->read_proto == SNOR_PROTO_8_8_8_DTR) {
                /*
                 * In 8D-8D-8D mode, one byte takes half a cycle to transfer. So
                 * in this protocol an odd addr_nbytes cannot be used because
                 * then the address phase would only span a cycle and a half.
                 * Half a cycle would be left over. We would then have to start
                 * the dummy phase in the middle of a cycle and so too the data
                 * phase, and we will end the transaction with half a cycle left
                 * over.
                 *
                 * Force all 8D-8D-8D flashes to use an addr_nbytes of 4 to
                 * avoid this situation.
                 */
                nor->addr_nbytes = 4;
        } else if (nor->info->addr_nbytes) {
                nor->addr_nbytes = nor->info->addr_nbytes;
        } else {
                nor->addr_nbytes = 3;
        }

        if (nor->addr_nbytes == 3 && nor->params->size > 0x1000000) {
                /* enable 4-byte addressing if the device exceeds 16MiB */
                nor->addr_nbytes = 4;
        }

        if (nor->addr_nbytes > SPI_NOR_MAX_ADDR_NBYTES) {
                dev_dbg(nor->dev, "The number of address bytes is too large: %u\n",
                        nor->addr_nbytes);
                return -EINVAL;
        }

        /* Set 4byte opcodes when possible. */
        if (nor->addr_nbytes == 4 && nor->flags & SNOR_F_4B_OPCODES &&
            !(nor->flags & SNOR_F_HAS_4BAIT))
                spi_nor_set_4byte_opcodes(nor);

        return 0;
}

static int spi_nor_setup(struct spi_nor *nor,
                         const struct spi_nor_hwcaps *hwcaps)
{
        int ret;

        if (nor->params->setup)
                ret = nor->params->setup(nor, hwcaps);
        else
                ret = spi_nor_default_setup(nor, hwcaps);
        if (ret)
                return ret;

        return spi_nor_set_addr_nbytes(nor);
}

/**
 * spi_nor_manufacturer_init_params() - Initialize the flash's parameters and
 * settings based on MFR register and ->default_init() hook.
 * @nor:        pointer to a 'struct spi_nor'.
 */
static void spi_nor_manufacturer_init_params(struct spi_nor *nor)
{
        if (nor->manufacturer && nor->manufacturer->fixups &&
            nor->manufacturer->fixups->default_init)
                nor->manufacturer->fixups->default_init(nor);

        if (nor->info->fixups && nor->info->fixups->default_init)
                nor->info->fixups->default_init(nor);
}

/**
 * spi_nor_no_sfdp_init_params() - Initialize the flash's parameters and
 * settings based on nor->info->sfdp_flags. This method should be called only by
 * flashes that do not define SFDP tables. If the flash supports SFDP but the
 * information is wrong and the settings from this function can not be retrieved
 * by parsing SFDP, one should instead use the fixup hooks and update the wrong
 * bits.
 * @nor:        pointer to a 'struct spi_nor'.
 */
static void spi_nor_no_sfdp_init_params(struct spi_nor *nor)
{
        struct spi_nor_flash_parameter *params = nor->params;
        struct spi_nor_erase_map *map = &params->erase_map;
        const u8 no_sfdp_flags = nor->info->no_sfdp_flags;
        u8 i, erase_mask;

        if (no_sfdp_flags & SPI_NOR_DUAL_READ) {
                params->hwcaps.mask |= SNOR_HWCAPS_READ_1_1_2;
                spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_1_1_2],
                                          0, 8, SPINOR_OP_READ_1_1_2,
                                          SNOR_PROTO_1_1_2);
        }

        if (no_sfdp_flags & SPI_NOR_QUAD_READ) {
                params->hwcaps.mask |= SNOR_HWCAPS_READ_1_1_4;
                spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_1_1_4],
                                          0, 8, SPINOR_OP_READ_1_1_4,
                                          SNOR_PROTO_1_1_4);
        }

        if (no_sfdp_flags & SPI_NOR_OCTAL_READ) {
                params->hwcaps.mask |= SNOR_HWCAPS_READ_1_1_8;
                spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_1_1_8],
                                          0, 8, SPINOR_OP_READ_1_1_8,
                                          SNOR_PROTO_1_1_8);
        }

        if (no_sfdp_flags & SPI_NOR_OCTAL_DTR_READ) {
                params->hwcaps.mask |= SNOR_HWCAPS_READ_8_8_8_DTR;
                spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_8_8_8_DTR],
                                          0, 20, SPINOR_OP_READ_FAST,
                                          SNOR_PROTO_8_8_8_DTR);
        }

        if (no_sfdp_flags & SPI_NOR_OCTAL_DTR_PP) {
                params->hwcaps.mask |= SNOR_HWCAPS_PP_8_8_8_DTR;
                /*
                 * Since xSPI Page Program opcode is backward compatible with
                 * Legacy SPI, use Legacy SPI opcode there as well.
                 */
                spi_nor_set_pp_settings(&params->page_programs[SNOR_CMD_PP_8_8_8_DTR],
                                        SPINOR_OP_PP, SNOR_PROTO_8_8_8_DTR);
        }

        /*
         * Sector Erase settings. Sort Erase Types in ascending order, with the
         * smallest erase size starting at BIT(0).
         */
        erase_mask = 0;
        i = 0;
        if (no_sfdp_flags & SECT_4K) {
                erase_mask |= BIT(i);
                spi_nor_set_erase_type(&map->erase_type[i], 4096u,
                                       SPINOR_OP_BE_4K);
                i++;
        }
        erase_mask |= BIT(i);
        spi_nor_set_erase_type(&map->erase_type[i], nor->info->sector_size,
                               SPINOR_OP_SE);
        spi_nor_init_uniform_erase_map(map, erase_mask, params->size);
}

/**
 * spi_nor_init_flags() - Initialize NOR flags for settings that are not defined
 * in the JESD216 SFDP standard, thus can not be retrieved when parsing SFDP.
 * @nor:        pointer to a 'struct spi_nor'
 */
static void spi_nor_init_flags(struct spi_nor *nor)
{
        struct device_node *np = spi_nor_get_flash_node(nor);
        const u16 flags = nor->info->flags;

        if (of_property_read_bool(np, "broken-flash-reset"))
                nor->flags |= SNOR_F_BROKEN_RESET;

        if (flags & SPI_NOR_SWP_IS_VOLATILE)
                nor->flags |= SNOR_F_SWP_IS_VOLATILE;

        if (flags & SPI_NOR_HAS_LOCK)
                nor->flags |= SNOR_F_HAS_LOCK;

        if (flags & SPI_NOR_HAS_TB) {
                nor->flags |= SNOR_F_HAS_SR_TB;
                if (flags & SPI_NOR_TB_SR_BIT6)
                        nor->flags |= SNOR_F_HAS_SR_TB_BIT6;
        }

        if (flags & SPI_NOR_4BIT_BP) {
                nor->flags |= SNOR_F_HAS_4BIT_BP;
                if (flags & SPI_NOR_BP3_SR_BIT6)
                        nor->flags |= SNOR_F_HAS_SR_BP3_BIT6;
        }

        if (flags & NO_CHIP_ERASE)
                nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
}

/**
 * spi_nor_init_fixup_flags() - Initialize NOR flags for settings that can not
 * be discovered by SFDP for this particular flash because the SFDP table that
 * indicates this support is not defined in the flash. In case the table for
 * this support is defined but has wrong values, one should instead use a
 * post_sfdp() hook to set the SNOR_F equivalent flag.
 * @nor:       pointer to a 'struct spi_nor'
 */
static void spi_nor_init_fixup_flags(struct spi_nor *nor)
{
        const u8 fixup_flags = nor->info->fixup_flags;

        if (fixup_flags & SPI_NOR_4B_OPCODES)
                nor->flags |= SNOR_F_4B_OPCODES;

        if (fixup_flags & SPI_NOR_IO_MODE_EN_VOLATILE)
                nor->flags |= SNOR_F_IO_MODE_EN_VOLATILE;
}

/**
 * spi_nor_late_init_params() - Late initialization of default flash parameters.
 * @nor:        pointer to a 'struct spi_nor'
 *
 * Used to initialize flash parameters that are not declared in the JESD216
 * SFDP standard, or where SFDP tables are not defined at all.
 * Will replace the spi_nor_manufacturer_init_params() method.
 */
static void spi_nor_late_init_params(struct spi_nor *nor)
{
        if (nor->manufacturer && nor->manufacturer->fixups &&
            nor->manufacturer->fixups->late_init)
                nor->manufacturer->fixups->late_init(nor);

        if (nor->info->fixups && nor->info->fixups->late_init)
                nor->info->fixups->late_init(nor);

        spi_nor_init_flags(nor);
        spi_nor_init_fixup_flags(nor);

        /*
         * NOR protection support. When locking_ops are not provided, we pick
         * the default ones.
         */
        if (nor->flags & SNOR_F_HAS_LOCK && !nor->params->locking_ops)
                spi_nor_init_default_locking_ops(nor);
}

/**
 * spi_nor_sfdp_init_params_deprecated() - Deprecated way of initializing flash
 * parameters and settings based on JESD216 SFDP standard.
 * @nor:        pointer to a 'struct spi_nor'.
 *
 * The method has a roll-back mechanism: in case the SFDP parsing fails, the
 * legacy flash parameters and settings will be restored.
 */
static void spi_nor_sfdp_init_params_deprecated(struct spi_nor *nor)
{
        struct spi_nor_flash_parameter sfdp_params;

        memcpy(&sfdp_params, nor->params, sizeof(sfdp_params));

        if (spi_nor_parse_sfdp(nor)) {
                memcpy(nor->params, &sfdp_params, sizeof(*nor->params));
                nor->flags &= ~SNOR_F_4B_OPCODES;
        }
}

/**
 * spi_nor_init_params_deprecated() - Deprecated way of initializing flash
 * parameters and settings.
 * @nor:        pointer to a 'struct spi_nor'.
 *
 * The method assumes that flash doesn't support SFDP so it initializes flash
 * parameters in spi_nor_no_sfdp_init_params() which later on can be overwritten
 * when parsing SFDP, if supported.
 */
static void spi_nor_init_params_deprecated(struct spi_nor *nor)
{
        spi_nor_no_sfdp_init_params(nor);

        spi_nor_manufacturer_init_params(nor);

        if (nor->info->no_sfdp_flags & (SPI_NOR_DUAL_READ |
                                        SPI_NOR_QUAD_READ |
                                        SPI_NOR_OCTAL_READ |
                                        SPI_NOR_OCTAL_DTR_READ))
                spi_nor_sfdp_init_params_deprecated(nor);
}

/**
 * spi_nor_init_default_params() - Default initialization of flash parameters
 * and settings. Done for all flashes, regardless is they define SFDP tables
 * or not.
 * @nor:        pointer to a 'struct spi_nor'.
 */
static void spi_nor_init_default_params(struct spi_nor *nor)
{
        struct spi_nor_flash_parameter *params = nor->params;
        const struct flash_info *info = nor->info;
        struct device_node *np = spi_nor_get_flash_node(nor);

        params->quad_enable = spi_nor_sr2_bit1_quad_enable;
        params->set_4byte_addr_mode = spansion_set_4byte_addr_mode;
        params->otp.org = &info->otp_org;

        /* Default to 16-bit Write Status (01h) Command */
        nor->flags |= SNOR_F_HAS_16BIT_SR;

        /* Set SPI NOR sizes. */
        params->writesize = 1;
        params->size = (u64)info->sector_size * info->n_sectors;
        params->page_size = info->page_size;

        if (!(info->flags & SPI_NOR_NO_FR)) {
                /* Default to Fast Read for DT and non-DT platform devices. */
                params->hwcaps.mask |= SNOR_HWCAPS_READ_FAST;

                /* Mask out Fast Read if not requested at DT instantiation. */
                if (np && !of_property_read_bool(np, "m25p,fast-read"))
                        params->hwcaps.mask &= ~SNOR_HWCAPS_READ_FAST;
        }

        /* (Fast) Read settings. */
        params->hwcaps.mask |= SNOR_HWCAPS_READ;
        spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ],
                                  0, 0, SPINOR_OP_READ,
                                  SNOR_PROTO_1_1_1);

        if (params->hwcaps.mask & SNOR_HWCAPS_READ_FAST)
                spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_FAST],
                                          0, 8, SPINOR_OP_READ_FAST,
                                          SNOR_PROTO_1_1_1);
        /* Page Program settings. */
        params->hwcaps.mask |= SNOR_HWCAPS_PP;
        spi_nor_set_pp_settings(&params->page_programs[SNOR_CMD_PP],
                                SPINOR_OP_PP, SNOR_PROTO_1_1_1);

        if (info->flags & SPI_NOR_QUAD_PP) {
                params->hwcaps.mask |= SNOR_HWCAPS_PP_1_1_4;
                spi_nor_set_pp_settings(&params->page_programs[SNOR_CMD_PP_1_1_4],
                                        SPINOR_OP_PP_1_1_4, SNOR_PROTO_1_1_4);
        }
}

/**
 * spi_nor_init_params() - Initialize the flash's parameters and settings.
 * @nor:        pointer to a 'struct spi_nor'.
 *
 * The flash parameters and settings are initialized based on a sequence of
 * calls that are ordered by priority:
 *
 * 1/ Default flash parameters initialization. The initializations are done
 *    based on nor->info data:
 *              spi_nor_info_init_params()
 *
 * which can be overwritten by:
 * 2/ Manufacturer flash parameters initialization. The initializations are
 *    done based on MFR register, or when the decisions can not be done solely
 *    based on MFR, by using specific flash_info tweeks, ->default_init():
 *              spi_nor_manufacturer_init_params()
 *
 * which can be overwritten by:
 * 3/ SFDP flash parameters initialization. JESD216 SFDP is a standard and
 *    should be more accurate that the above.
 *              spi_nor_parse_sfdp() or spi_nor_no_sfdp_init_params()
 *
 *    Please note that there is a ->post_bfpt() fixup hook that can overwrite
 *    the flash parameters and settings immediately after parsing the Basic
 *    Flash Parameter Table.
 *    spi_nor_post_sfdp_fixups() is called after the SFDP tables are parsed.
 *    It is used to tweak various flash parameters when information provided
 *    by the SFDP tables are wrong.
 *
 * which can be overwritten by:
 * 4/ Late flash parameters initialization, used to initialize flash
 * parameters that are not declared in the JESD216 SFDP standard, or where SFDP
 * tables are not defined at all.
 *              spi_nor_late_init_params()
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_init_params(struct spi_nor *nor)
{
        int ret;

        nor->params = devm_kzalloc(nor->dev, sizeof(*nor->params), GFP_KERNEL);
        if (!nor->params)
                return -ENOMEM;

        spi_nor_init_default_params(nor);

        if (nor->info->parse_sfdp) {
                ret = spi_nor_parse_sfdp(nor);
                if (ret) {
                        dev_err(nor->dev, "BFPT parsing failed. Please consider using SPI_NOR_SKIP_SFDP when declaring the flash\n");
                        return ret;
                }
        } else if (nor->info->no_sfdp_flags & SPI_NOR_SKIP_SFDP) {
                spi_nor_no_sfdp_init_params(nor);
        } else {
                spi_nor_init_params_deprecated(nor);
        }

        spi_nor_late_init_params(nor);

        return 0;
}

/** spi_nor_octal_dtr_enable() - enable Octal DTR I/O if needed
 * @nor:                 pointer to a 'struct spi_nor'
 * @enable:              whether to enable or disable Octal DTR
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_octal_dtr_enable(struct spi_nor *nor, bool enable)
{
        int ret;

        if (!nor->params->octal_dtr_enable)
                return 0;

        if (!(nor->read_proto == SNOR_PROTO_8_8_8_DTR &&
              nor->write_proto == SNOR_PROTO_8_8_8_DTR))
                return 0;

        if (!(nor->flags & SNOR_F_IO_MODE_EN_VOLATILE))
                return 0;

        ret = nor->params->octal_dtr_enable(nor, enable);
        if (ret)
                return ret;

        if (enable)
                nor->reg_proto = SNOR_PROTO_8_8_8_DTR;
        else
                nor->reg_proto = SNOR_PROTO_1_1_1;

        return 0;
}

/**
 * spi_nor_quad_enable() - enable Quad I/O if needed.
 * @nor:                pointer to a 'struct spi_nor'
 *
 * Return: 0 on success, -errno otherwise.
 */
static int spi_nor_quad_enable(struct spi_nor *nor)
{
        if (!nor->params->quad_enable)
                return 0;

        if (!(spi_nor_get_protocol_width(nor->read_proto) == 4 ||
              spi_nor_get_protocol_width(nor->write_proto) == 4))
                return 0;

        return nor->params->quad_enable(nor);
}

static int spi_nor_init(struct spi_nor *nor)
{
        int err;

        err = spi_nor_octal_dtr_enable(nor, true);
        if (err) {
                dev_dbg(nor->dev, "octal mode not supported\n");
                return err;
        }

        err = spi_nor_quad_enable(nor);
        if (err) {
                dev_dbg(nor->dev, "quad mode not supported\n");
                return err;
        }

        /*
         * Some SPI NOR flashes are write protected by default after a power-on
         * reset cycle, in order to avoid inadvertent writes during power-up.
         * Backward compatibility imposes to unlock the entire flash memory
         * array at power-up by default. Depending on the kernel configuration
         * (1) do nothing, (2) always unlock the entire flash array or (3)
         * unlock the entire flash array only when the software write
         * protection bits are volatile. The latter is indicated by
         * SNOR_F_SWP_IS_VOLATILE.
         */
        if (IS_ENABLED(CONFIG_MTD_SPI_NOR_SWP_DISABLE) ||
            (IS_ENABLED(CONFIG_MTD_SPI_NOR_SWP_DISABLE_ON_VOLATILE) &&
             nor->flags & SNOR_F_SWP_IS_VOLATILE))
                spi_nor_try_unlock_all(nor);

        if (nor->addr_nbytes == 4 &&
            nor->read_proto != SNOR_PROTO_8_8_8_DTR &&
            !(nor->flags & SNOR_F_4B_OPCODES)) {
                /*
                 * If the RESET# pin isn't hooked up properly, or the system
                 * otherwise doesn't perform a reset command in the boot
                 * sequence, it's impossible to 100% protect against unexpected
                 * reboots (e.g., crashes). Warn the user (or hopefully, system
                 * designer) that this is bad.
                 */
                WARN_ONCE(nor->flags & SNOR_F_BROKEN_RESET,
                          "enabling reset hack; may not recover from unexpected reboots\n");
                err = nor->params->set_4byte_addr_mode(nor, true);
                if (err && err != -ENOTSUPP)
                        return err;
        }

        return 0;
}

/**
 * spi_nor_soft_reset() - Perform a software reset
 * @nor:        pointer to 'struct spi_nor'
 *
 * Performs a "Soft Reset and Enter Default Protocol Mode" sequence which resets
 * the device to its power-on-reset state. This is useful when the software has
 * made some changes to device (volatile) registers and needs to reset it before
 * shutting down, for example.
 *
 * Not every flash supports this sequence. The same set of opcodes might be used
 * for some other operation on a flash that does not support this. Support for
 * this sequence can be discovered via SFDP in the BFPT table.
 *
 * Return: 0 on success, -errno otherwise.
 */
static void spi_nor_soft_reset(struct spi_nor *nor)
{
        struct spi_mem_op op;
        int ret;

        op = (struct spi_mem_op)SPINOR_SRSTEN_OP;

        spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

        ret = spi_mem_exec_op(nor->spimem, &op);
        if (ret) {
                dev_warn(nor->dev, "Software reset failed: %d\n", ret);
                return;
        }

        op = (struct spi_mem_op)SPINOR_SRST_OP;

        spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);

        ret = spi_mem_exec_op(nor->spimem, &op);
        if (ret) {
                dev_warn(nor->dev, "Software reset failed: %d\n", ret);
                return;
        }

        /*
         * Software Reset is not instant, and the delay varies from flash to
         * flash. Looking at a few flashes, most range somewhere below 100
         * microseconds. So, sleep for a range of 200-400 us.
         */
        usleep_range(SPI_NOR_SRST_SLEEP_MIN, SPI_NOR_SRST_SLEEP_MAX);
}

/* mtd suspend handler */
static int spi_nor_suspend(struct mtd_info *mtd)
{
        struct spi_nor *nor = mtd_to_spi_nor(mtd);
        int ret;

        /* Disable octal DTR mode if we enabled it. */
        ret = spi_nor_octal_dtr_enable(nor, false);
        if (ret)
                dev_err(nor->dev, "suspend() failed\n");

        return ret;
}

/* mtd resume handler */
static void spi_nor_resume(struct mtd_info *mtd)
{
        struct spi_nor *nor = mtd_to_spi_nor(mtd);
        struct device *dev = nor->dev;
        int ret;

        /* re-initialize the nor chip */
        ret = spi_nor_init(nor);
        if (ret)
                dev_err(dev, "resume() failed\n");
}

static int spi_nor_get_device(struct mtd_info *mtd)
{
        struct mtd_info *master = mtd_get_master(mtd);
        struct spi_nor *nor = mtd_to_spi_nor(master);
        struct device *dev;

        if (nor->spimem)
                dev = nor->spimem->spi->controller->dev.parent;
        else
                dev = nor->dev;

        if (!try_module_get(dev->driver->owner))
                return -ENODEV;

        return 0;
}

static void spi_nor_put_device(struct mtd_info *mtd)
{
        struct mtd_info *master = mtd_get_master(mtd);
        struct spi_nor *nor = mtd_to_spi_nor(master);
        struct device *dev;

        if (nor->spimem)
                dev = nor->spimem->spi->controller->dev.parent;
        else
                dev = nor->dev;

        module_put(dev->driver->owner);
}

void spi_nor_restore(struct spi_nor *nor)
{
        int ret;

        /* restore the addressing mode */
        if (nor->addr_nbytes == 4 && !(nor->flags & SNOR_F_4B_OPCODES) &&
            nor->flags & SNOR_F_BROKEN_RESET) {
                ret = nor->params->set_4byte_addr_mode(nor, false);
                if (ret)
                        /*
                         * Do not stop the execution in the hope that the flash
                         * will default to the 3-byte address mode after the
                         * software reset.
                         */
                        dev_err(nor->dev, "Failed to exit 4-byte address mode, err = %d\n", ret);
        }

        if (nor->flags & SNOR_F_SOFT_RESET)
                spi_nor_soft_reset(nor);
}
EXPORT_SYMBOL_GPL(spi_nor_restore);

static const struct flash_info *spi_nor_match_name(struct spi_nor *nor,
                                                   const char *name)
{
        unsigned int i, j;

        for (i = 0; i < ARRAY_SIZE(manufacturers); i++) {
                for (j = 0; j < manufacturers[i]->nparts; j++) {
                        if (!strcmp(name, manufacturers[i]->parts[j].name)) {
                                nor->manufacturer = manufacturers[i];
                                return &manufacturers[i]->parts[j];
                        }
                }
        }

        return NULL;
}

static const struct flash_info *spi_nor_get_flash_info(struct spi_nor *nor,
                                                       const char *name)
{
        const struct flash_info *info = NULL;

        if (name)
                info = spi_nor_match_name(nor, name);
        /* Try to auto-detect if chip name wasn't specified or not found */
        if (!info)
                return spi_nor_detect(nor);

        /*
         * If caller has specified name of flash model that can normally be
         * detected using JEDEC, let's verify it.
         */
        if (name && info->id_len) {
                const struct flash_info *jinfo;

                jinfo = spi_nor_detect(nor);
                if (IS_ERR(jinfo)) {
                        return jinfo;
                } else if (jinfo != info) {
                        /*
                         * JEDEC knows better, so overwrite platform ID. We
                         * can't trust partitions any longer, but we'll let
                         * mtd apply them anyway, since some partitions may be
                         * marked read-only, and we don't want to lose that
                         * information, even if it's not 100% accurate.
                         */
                        dev_warn(nor->dev, "found %s, expected %s\n",
                                 jinfo->name, info->name);
                        info = jinfo;
                }
        }

        return info;
}

static void spi_nor_set_mtd_info(struct spi_nor *nor)
{
        struct mtd_info *mtd = &nor->mtd;
        struct device *dev = nor->dev;

        spi_nor_set_mtd_locking_ops(nor);
        spi_nor_set_mtd_otp_ops(nor);

        mtd->dev.parent = dev;
        if (!mtd->name)
                mtd->name = dev_name(dev);
        mtd->type = MTD_NORFLASH;
        mtd->flags = MTD_CAP_NORFLASH;
        if (nor->info->flags & SPI_NOR_NO_ERASE)
                mtd->flags |= MTD_NO_ERASE;
        else
                mtd->_erase = spi_nor_erase;
        mtd->writesize = nor->params->writesize;
        mtd->writebufsize = nor->params->page_size;
        mtd->size = nor->params->size;
        mtd->_read = spi_nor_read;
        /* Might be already set by some SST flashes. */
        if (!mtd->_write)
                mtd->_write = spi_nor_write;
        mtd->_suspend = spi_nor_suspend;
        mtd->_resume = spi_nor_resume;
        mtd->_get_device = spi_nor_get_device;
        mtd->_put_device = spi_nor_put_device;
}

static int spi_nor_hw_reset(struct spi_nor *nor)
{
        struct gpio_desc *reset;

        reset = devm_gpiod_get_optional(nor->dev, "reset", GPIOD_OUT_LOW);
        if (IS_ERR_OR_NULL(reset))
                return PTR_ERR_OR_ZERO(reset);

        /*
         * Experimental delay values by looking at different flash device
         * vendors datasheets.
         */
        usleep_range(1, 5);
        gpiod_set_value_cansleep(reset, 1);
        usleep_range(100, 150);
        gpiod_set_value_cansleep(reset, 0);
        usleep_range(1000, 1200);

        return 0;
}

int spi_nor_scan(struct spi_nor *nor, const char *name,
                 const struct spi_nor_hwcaps *hwcaps)
{
        const struct flash_info *info;
        struct device *dev = nor->dev;
        struct mtd_info *mtd = &nor->mtd;
        int ret;
        int i;

        ret = spi_nor_check(nor);
        if (ret)
                return ret;

        /* Reset SPI protocol for all commands. */
        nor->reg_proto = SNOR_PROTO_1_1_1;
        nor->read_proto = SNOR_PROTO_1_1_1;
        nor->write_proto = SNOR_PROTO_1_1_1;

        /*
         * We need the bounce buffer early to read/write registers when going
         * through the spi-mem layer (buffers have to be DMA-able).
         * For spi-mem drivers, we'll reallocate a new buffer if
         * nor->params->page_size turns out to be greater than PAGE_SIZE (which
         * shouldn't happen before long since NOR pages are usually less
         * than 1KB) after spi_nor_scan() returns.
         */
        nor->bouncebuf_size = PAGE_SIZE;
        nor->bouncebuf = devm_kmalloc(dev, nor->bouncebuf_size,
                                      GFP_KERNEL);
        if (!nor->bouncebuf)
                return -ENOMEM;

        ret = spi_nor_hw_reset(nor);
        if (ret)
                return ret;

        info = spi_nor_get_flash_info(nor, name);
        if (IS_ERR(info))
                return PTR_ERR(info);

        nor->info = info;

        mutex_init(&nor->lock);

        /* Init flash parameters based on flash_info struct and SFDP */
        ret = spi_nor_init_params(nor);
        if (ret)
                return ret;

        /*
         * Configure the SPI memory:
         * - select op codes for (Fast) Read, Page Program and Sector Erase.
         * - set the number of dummy cycles (mode cycles + wait states).
         * - set the SPI protocols for register and memory accesses.
         * - set the number of address bytes.
         */
        ret = spi_nor_setup(nor, hwcaps);
        if (ret)
                return ret;

        /* Send all the required SPI flash commands to initialize device */
        ret = spi_nor_init(nor);
        if (ret)
                return ret;

        /* No mtd_info fields should be used up to this point. */
        spi_nor_set_mtd_info(nor);

        dev_info(dev, "%s (%lld Kbytes)\n", info->name,
                        (long long)mtd->size >> 10);

        dev_dbg(dev,
                "mtd .name = %s, .size = 0x%llx (%lldMiB), "
                ".erasesize = 0x%.8x (%uKiB) .numeraseregions = %d\n",
                mtd->name, (long long)mtd->size, (long long)(mtd->size >> 20),
                mtd->erasesize, mtd->erasesize / 1024, mtd->numeraseregions);

        if (mtd->numeraseregions)
                for (i = 0; i < mtd->numeraseregions; i++)
                        dev_dbg(dev,
                                "mtd.eraseregions[%d] = { .offset = 0x%llx, "
                                ".erasesize = 0x%.8x (%uKiB), "
                                ".numblocks = %d }\n",
                                i, (long long)mtd->eraseregions[i].offset,
                                mtd->eraseregions[i].erasesize,
                                mtd->eraseregions[i].erasesize / 1024,
                                mtd->eraseregions[i].numblocks);
        return 0;
}
EXPORT_SYMBOL_GPL(spi_nor_scan);

static int spi_nor_create_read_dirmap(struct spi_nor *nor)
{
        struct spi_mem_dirmap_info info = {
                .op_tmpl = SPI_MEM_OP(SPI_MEM_OP_CMD(nor->read_opcode, 0),
                                      SPI_MEM_OP_ADDR(nor->addr_nbytes, 0, 0),
                                      SPI_MEM_OP_DUMMY(nor->read_dummy, 0),
                                      SPI_MEM_OP_DATA_IN(0, NULL, 0)),
                .offset = 0,
                .length = nor->params->size,
        };
        struct spi_mem_op *op = &info.op_tmpl;

        spi_nor_spimem_setup_op(nor, op, nor->read_proto);

        /* convert the dummy cycles to the number of bytes */
        op->dummy.nbytes = (nor->read_dummy * op->dummy.buswidth) / 8;
        if (spi_nor_protocol_is_dtr(nor->read_proto))
                op->dummy.nbytes *= 2;

        /*
         * Since spi_nor_spimem_setup_op() only sets buswidth when the number
         * of data bytes is non-zero, the data buswidth won't be set here. So,
         * do it explicitly.
         */
        op->data.buswidth = spi_nor_get_protocol_data_nbits(nor->read_proto);

        nor->dirmap.rdesc = devm_spi_mem_dirmap_create(nor->dev, nor->spimem,
                                                       &info);
        return PTR_ERR_OR_ZERO(nor->dirmap.rdesc);
}

static int spi_nor_create_write_dirmap(struct spi_nor *nor)
{
        struct spi_mem_dirmap_info info = {
                .op_tmpl = SPI_MEM_OP(SPI_MEM_OP_CMD(nor->program_opcode, 0),
                                      SPI_MEM_OP_ADDR(nor->addr_nbytes, 0, 0),
                                      SPI_MEM_OP_NO_DUMMY,
                                      SPI_MEM_OP_DATA_OUT(0, NULL, 0)),
                .offset = 0,
                .length = nor->params->size,
        };
        struct spi_mem_op *op = &info.op_tmpl;

        if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
                op->addr.nbytes = 0;

        spi_nor_spimem_setup_op(nor, op, nor->write_proto);

        /*
         * Since spi_nor_spimem_setup_op() only sets buswidth when the number
         * of data bytes is non-zero, the data buswidth won't be set here. So,
         * do it explicitly.
         */
        op->data.buswidth = spi_nor_get_protocol_data_nbits(nor->write_proto);

        nor->dirmap.wdesc = devm_spi_mem_dirmap_create(nor->dev, nor->spimem,
                                                       &info);
        return PTR_ERR_OR_ZERO(nor->dirmap.wdesc);
}

static int spi_nor_probe(struct spi_mem *spimem)
{
        struct spi_device *spi = spimem->spi;
        struct flash_platform_data *data = dev_get_platdata(&spi->dev);
        struct spi_nor *nor;
        /*
         * Enable all caps by default. The core will mask them after
         * checking what's really supported using spi_mem_supports_op().
         */
        const struct spi_nor_hwcaps hwcaps = { .mask = SNOR_HWCAPS_ALL };
        char *flash_name;
        int ret;

        nor = devm_kzalloc(&spi->dev, sizeof(*nor), GFP_KERNEL);
        if (!nor)
                return -ENOMEM;

        nor->spimem = spimem;
        nor->dev = &spi->dev;
        spi_nor_set_flash_node(nor, spi->dev.of_node);

        spi_mem_set_drvdata(spimem, nor);

        if (data && data->name)
                nor->mtd.name = data->name;

        if (!nor->mtd.name)
                nor->mtd.name = spi_mem_get_name(spimem);

        /*
         * For some (historical?) reason many platforms provide two different
         * names in flash_platform_data: "name" and "type". Quite often name is
         * set to "m25p80" and then "type" provides a real chip name.
         * If that's the case, respect "type" and ignore a "name".
         */
        if (data && data->type)
                flash_name = data->type;
        else if (!strcmp(spi->modalias, "spi-nor"))
                flash_name = NULL; /* auto-detect */
        else
                flash_name = spi->modalias;

        ret = spi_nor_scan(nor, flash_name, &hwcaps);
        if (ret)
                return ret;

        spi_nor_debugfs_register(nor);

        /*
         * None of the existing parts have > 512B pages, but let's play safe
         * and add this logic so that if anyone ever adds support for such
         * a NOR we don't end up with buffer overflows.
         */
        if (nor->params->page_size > PAGE_SIZE) {
                nor->bouncebuf_size = nor->params->page_size;
                devm_kfree(nor->dev, nor->bouncebuf);
                nor->bouncebuf = devm_kmalloc(nor->dev,
                                              nor->bouncebuf_size,
                                              GFP_KERNEL);
                if (!nor->bouncebuf)
                        return -ENOMEM;
        }

        ret = spi_nor_create_read_dirmap(nor);
        if (ret)
                return ret;

        ret = spi_nor_create_write_dirmap(nor);
        if (ret)
                return ret;

        return mtd_device_register(&nor->mtd, data ? data->parts : NULL,
                                   data ? data->nr_parts : 0);
}

static int spi_nor_remove(struct spi_mem *spimem)
{
        struct spi_nor *nor = spi_mem_get_drvdata(spimem);

        spi_nor_restore(nor);

        /* Clean up MTD stuff. */
        return mtd_device_unregister(&nor->mtd);
}

static void spi_nor_shutdown(struct spi_mem *spimem)
{
        struct spi_nor *nor = spi_mem_get_drvdata(spimem);

        spi_nor_restore(nor);
}

/*
 * Do NOT add to this array without reading the following:
 *
 * Historically, many flash devices are bound to this driver by their name. But
 * since most of these flash are compatible to some extent, and their
 * differences can often be differentiated by the JEDEC read-ID command, we
 * encourage new users to add support to the spi-nor library, and simply bind
 * against a generic string here (e.g., "jedec,spi-nor").
 *
 * Many flash names are kept here in this list to keep them available
 * as module aliases for existing platforms.
 */
static const struct spi_device_id spi_nor_dev_ids[] = {
        /*
         * Allow non-DT platform devices to bind to the "spi-nor" modalias, and
         * hack around the fact that the SPI core does not provide uevent
         * matching for .of_match_table
         */
        {"spi-nor"},

        /*
         * Entries not used in DTs that should be safe to drop after replacing
         * them with "spi-nor" in platform data.
         */
        {"s25sl064a"},  {"w25x16"},     {"m25p10"},     {"m25px64"},

        /*
         * Entries that were used in DTs without "jedec,spi-nor" fallback and
         * should be kept for backward compatibility.
         */
        {"at25df321a"}, {"at25df641"},  {"at26df081a"},
        {"mx25l4005a"}, {"mx25l1606e"}, {"mx25l6405d"}, {"mx25l12805d"},
        {"mx25l25635e"},{"mx66l51235l"},
        {"n25q064"},    {"n25q128a11"}, {"n25q128a13"}, {"n25q512a"},
        {"s25fl256s1"}, {"s25fl512s"},  {"s25sl12801"}, {"s25fl008k"},
        {"s25fl064k"},
        {"sst25vf040b"},{"sst25vf016b"},{"sst25vf032b"},{"sst25wf040"},
        {"m25p40"},     {"m25p80"},     {"m25p16"},     {"m25p32"},
        {"m25p64"},     {"m25p128"},
        {"w25x80"},     {"w25x32"},     {"w25q32"},     {"w25q32dw"},
        {"w25q80bl"},   {"w25q128"},    {"w25q256"},

        /* Flashes that can't be detected using JEDEC */
        {"m25p05-nonjedec"},    {"m25p10-nonjedec"},    {"m25p20-nonjedec"},
        {"m25p40-nonjedec"},    {"m25p80-nonjedec"},    {"m25p16-nonjedec"},
        {"m25p32-nonjedec"},    {"m25p64-nonjedec"},    {"m25p128-nonjedec"},

        /* Everspin MRAMs (non-JEDEC) */
        { "mr25h128" }, /* 128 Kib, 40 MHz */
        { "mr25h256" }, /* 256 Kib, 40 MHz */
        { "mr25h10" },  /*   1 Mib, 40 MHz */
        { "mr25h40" },  /*   4 Mib, 40 MHz */

        { },
};
MODULE_DEVICE_TABLE(spi, spi_nor_dev_ids);

static const struct of_device_id spi_nor_of_table[] = {
        /*
         * Generic compatibility for SPI NOR that can be identified by the
         * JEDEC READ ID opcode (0x9F). Use this, if possible.
         */
        { .compatible = "jedec,spi-nor" },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, spi_nor_of_table);

/*
 * REVISIT: many of these chips have deep power-down modes, which
 * should clearly be entered on suspend() to minimize power use.
 * And also when they're otherwise idle...
 */
static struct spi_mem_driver spi_nor_driver = {
        .spidrv = {
                .driver = {
                        .name = "spi-nor",
                        .of_match_table = spi_nor_of_table,
                        .dev_groups = spi_nor_sysfs_groups,
                },
                .id_table = spi_nor_dev_ids,
        },
        .probe = spi_nor_probe,
        .remove = spi_nor_remove,
        .shutdown = spi_nor_shutdown,
};
module_spi_mem_driver(spi_nor_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Huang Shijie <shijie8@gmail.com>");
MODULE_AUTHOR("Mike Lavender");
MODULE_DESCRIPTION("framework for SPI NOR");