--- /dev/null
+// SPDX-License-Identifier: (GPL-2.0)
+/*
+ * Microchip CoreSPI SPI controller driver
+ *
+ * Copyright (c) 2018-2022 Microchip Technology Inc. and its subsidiaries
+ *
+ * Author: Daire McNamara <daire.mcnamara@microchip.com>
+ * Author: Conor Dooley <conor.dooley@microchip.com>
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+
+#define MAX_LEN (0xffff)
+#define MAX_CS (8)
+#define DEFAULT_FRAMESIZE (8)
+#define FIFO_DEPTH (32)
+#define CLK_GEN_MODE1_MAX (255)
+#define CLK_GEN_MODE0_MAX (15)
+#define CLK_GEN_MIN (0)
+#define MODE_X_MASK_SHIFT (24)
+
+#define CONTROL_ENABLE BIT(0)
+#define CONTROL_MASTER BIT(1)
+#define CONTROL_RX_DATA_INT BIT(4)
+#define CONTROL_TX_DATA_INT BIT(5)
+#define CONTROL_RX_OVER_INT BIT(6)
+#define CONTROL_TX_UNDER_INT BIT(7)
+#define CONTROL_SPO BIT(24)
+#define CONTROL_SPH BIT(25)
+#define CONTROL_SPS BIT(26)
+#define CONTROL_FRAMEURUN BIT(27)
+#define CONTROL_CLKMODE BIT(28)
+#define CONTROL_BIGFIFO BIT(29)
+#define CONTROL_OENOFF BIT(30)
+#define CONTROL_RESET BIT(31)
+
+#define CONTROL_MODE_MASK GENMASK(3, 2)
+#define MOTOROLA_MODE (0)
+#define CONTROL_FRAMECNT_MASK GENMASK(23, 8)
+#define CONTROL_FRAMECNT_SHIFT (8)
+
+#define STATUS_ACTIVE BIT(14)
+#define STATUS_SSEL BIT(13)
+#define STATUS_FRAMESTART BIT(12)
+#define STATUS_TXFIFO_EMPTY_NEXT_READ BIT(11)
+#define STATUS_TXFIFO_EMPTY BIT(10)
+#define STATUS_TXFIFO_FULL_NEXT_WRITE BIT(9)
+#define STATUS_TXFIFO_FULL BIT(8)
+#define STATUS_RXFIFO_EMPTY_NEXT_READ BIT(7)
+#define STATUS_RXFIFO_EMPTY BIT(6)
+#define STATUS_RXFIFO_FULL_NEXT_WRITE BIT(5)
+#define STATUS_RXFIFO_FULL BIT(4)
+#define STATUS_TX_UNDERRUN BIT(3)
+#define STATUS_RX_OVERFLOW BIT(2)
+#define STATUS_RXDAT_RXED BIT(1)
+#define STATUS_TXDAT_SENT BIT(0)
+
+#define INT_TXDONE BIT(0)
+#define INT_RXRDY BIT(1)
+#define INT_RX_CHANNEL_OVERFLOW BIT(2)
+#define INT_TX_CHANNEL_UNDERRUN BIT(3)
+
+#define INT_ENABLE_MASK (CONTROL_RX_DATA_INT | CONTROL_TX_DATA_INT | \
+ CONTROL_RX_OVER_INT | CONTROL_TX_UNDER_INT)
+
+#define REG_CONTROL (0x00)
+#define REG_FRAME_SIZE (0x04)
+#define REG_STATUS (0x08)
+#define REG_INT_CLEAR (0x0c)
+#define REG_RX_DATA (0x10)
+#define REG_TX_DATA (0x14)
+#define REG_CLK_GEN (0x18)
+#define REG_SLAVE_SELECT (0x1c)
+#define SSEL_MASK GENMASK(7, 0)
+#define SSEL_DIRECT BIT(8)
+#define SSELOUT_SHIFT 9
+#define SSELOUT BIT(SSELOUT_SHIFT)
+#define REG_MIS (0x20)
+#define REG_RIS (0x24)
+#define REG_CONTROL2 (0x28)
+#define REG_COMMAND (0x2c)
+#define REG_PKTSIZE (0x30)
+#define REG_CMD_SIZE (0x34)
+#define REG_HWSTATUS (0x38)
+#define REG_STAT8 (0x3c)
+#define REG_CTRL2 (0x48)
+#define REG_FRAMESUP (0x50)
+
+struct mchp_corespi {
+ void __iomem *regs;
+ struct clk *clk;
+ const u8 *tx_buf;
+ u8 *rx_buf;
+ u32 clk_gen; /* divider for spi output clock generated by the controller */
+ u32 clk_mode;
+ int irq;
+ int tx_len;
+ int rx_len;
+ int pending;
+};
+
+static inline u32 mchp_corespi_read(struct mchp_corespi *spi, unsigned int reg)
+{
+ return readl(spi->regs + reg);
+}
+
+static inline void mchp_corespi_write(struct mchp_corespi *spi, unsigned int reg, u32 val)
+{
+ writel(val, spi->regs + reg);
+}
+
+static inline void mchp_corespi_enable(struct mchp_corespi *spi)
+{
+ u32 control = mchp_corespi_read(spi, REG_CONTROL);
+
+ control |= CONTROL_ENABLE;
+
+ mchp_corespi_write(spi, REG_CONTROL, control);
+}
+
+static inline void mchp_corespi_disable(struct mchp_corespi *spi)
+{
+ u32 control = mchp_corespi_read(spi, REG_CONTROL);
+
+ control &= ~CONTROL_ENABLE;
+
+ mchp_corespi_write(spi, REG_CONTROL, control);
+}
+
+static inline void mchp_corespi_read_fifo(struct mchp_corespi *spi)
+{
+ u8 data;
+ int fifo_max, i = 0;
+
+ fifo_max = min(spi->rx_len, FIFO_DEPTH);
+
+ while ((i < fifo_max) && !(mchp_corespi_read(spi, REG_STATUS) & STATUS_RXFIFO_EMPTY)) {
+ data = mchp_corespi_read(spi, REG_RX_DATA);
+
+ if (spi->rx_buf)
+ *spi->rx_buf++ = data;
+ i++;
+ }
+ spi->rx_len -= i;
+ spi->pending -= i;
+}
+
+static void mchp_corespi_enable_ints(struct mchp_corespi *spi)
+{
+ u32 control, mask = INT_ENABLE_MASK;
+
+ mchp_corespi_disable(spi);
+
+ control = mchp_corespi_read(spi, REG_CONTROL);
+
+ control |= mask;
+ mchp_corespi_write(spi, REG_CONTROL, control);
+
+ control |= CONTROL_ENABLE;
+ mchp_corespi_write(spi, REG_CONTROL, control);
+}
+
+static void mchp_corespi_disable_ints(struct mchp_corespi *spi)
+{
+ u32 control, mask = INT_ENABLE_MASK;
+
+ mchp_corespi_disable(spi);
+
+ control = mchp_corespi_read(spi, REG_CONTROL);
+ control &= ~mask;
+ mchp_corespi_write(spi, REG_CONTROL, control);
+
+ control |= CONTROL_ENABLE;
+ mchp_corespi_write(spi, REG_CONTROL, control);
+}
+
+static inline void mchp_corespi_set_xfer_size(struct mchp_corespi *spi, int len)
+{
+ u32 control;
+ u16 lenpart;
+
+ /*
+ * Disable the SPI controller. Writes to transfer length have
+ * no effect when the controller is enabled.
+ */
+ mchp_corespi_disable(spi);
+
+ /*
+ * The lower 16 bits of the frame count are stored in the control reg
+ * for legacy reasons, but the upper 16 written to a different register:
+ * FRAMESUP. While both the upper and lower bits can be *READ* from the
+ * FRAMESUP register, writing to the lower 16 bits is a NOP
+ */
+ lenpart = len & 0xffff;
+
+ control = mchp_corespi_read(spi, REG_CONTROL);
+ control &= ~CONTROL_FRAMECNT_MASK;
+ control |= lenpart << CONTROL_FRAMECNT_SHIFT;
+ mchp_corespi_write(spi, REG_CONTROL, control);
+
+ lenpart = len & 0xffff0000;
+ mchp_corespi_write(spi, REG_FRAMESUP, lenpart);
+
+ control |= CONTROL_ENABLE;
+ mchp_corespi_write(spi, REG_CONTROL, control);
+}
+
+static inline void mchp_corespi_write_fifo(struct mchp_corespi *spi)
+{
+ u8 byte;
+ int fifo_max, i = 0;
+
+ fifo_max = min(spi->tx_len, FIFO_DEPTH);
+ mchp_corespi_set_xfer_size(spi, fifo_max);
+
+ while ((i < fifo_max) && !(mchp_corespi_read(spi, REG_STATUS) & STATUS_TXFIFO_FULL)) {
+ byte = spi->tx_buf ? *spi->tx_buf++ : 0xaa;
+ mchp_corespi_write(spi, REG_TX_DATA, byte);
+ i++;
+ }
+
+ spi->tx_len -= i;
+ spi->pending += i;
+}
+
+static inline void mchp_corespi_set_framesize(struct mchp_corespi *spi, int bt)
+{
+ u32 control;
+
+ /*
+ * Disable the SPI controller. Writes to the frame size have
+ * no effect when the controller is enabled.
+ */
+ mchp_corespi_disable(spi);
+
+ mchp_corespi_write(spi, REG_FRAME_SIZE, bt);
+
+ control = mchp_corespi_read(spi, REG_CONTROL);
+ control |= CONTROL_ENABLE;
+ mchp_corespi_write(spi, REG_CONTROL, control);
+}
+
+static void mchp_corespi_set_cs(struct spi_device *spi, bool disable)
+{
+ u32 reg;
+ struct mchp_corespi *corespi = spi_master_get_devdata(spi->master);
+
+ reg = mchp_corespi_read(corespi, REG_SLAVE_SELECT);
+ reg &= ~BIT(spi->chip_select);
+ reg |= !disable << spi->chip_select;
+
+ mchp_corespi_write(corespi, REG_SLAVE_SELECT, reg);
+}
+
+static int mchp_corespi_setup(struct spi_device *spi)
+{
+ struct mchp_corespi *corespi = spi_master_get_devdata(spi->master);
+ u32 reg;
+
+ /*
+ * Active high slaves need to be specifically set to their inactive
+ * states during probe by adding them to the "control group" & thus
+ * driving their select line low.
+ */
+ if (spi->mode & SPI_CS_HIGH) {
+ reg = mchp_corespi_read(corespi, REG_SLAVE_SELECT);
+ reg |= BIT(spi->chip_select);
+ mchp_corespi_write(corespi, REG_SLAVE_SELECT, reg);
+ }
+ return 0;
+}
+
+static void mchp_corespi_init(struct spi_master *master, struct mchp_corespi *spi)
+{
+ unsigned long clk_hz;
+ u32 control = mchp_corespi_read(spi, REG_CONTROL);
+
+ control |= CONTROL_MASTER;
+
+ control &= ~CONTROL_MODE_MASK;
+ control |= MOTOROLA_MODE;
+
+ mchp_corespi_set_framesize(spi, DEFAULT_FRAMESIZE);
+
+ /* max. possible spi clock rate is the apb clock rate */
+ clk_hz = clk_get_rate(spi->clk);
+ master->max_speed_hz = clk_hz;
+
+ /*
+ * The controller must be configured so that it doesn't remove Chip
+ * Select until the entire message has been transferred, even if at
+ * some points TX FIFO becomes empty.
+ *
+ * BIGFIFO mode is also enabled, which sets the fifo depth to 32 frames
+ * for the 8 bit transfers that this driver uses.
+ */
+ control = mchp_corespi_read(spi, REG_CONTROL);
+ control |= CONTROL_SPS | CONTROL_BIGFIFO;
+
+ mchp_corespi_write(spi, REG_CONTROL, control);
+
+ mchp_corespi_enable_ints(spi);
+
+ /*
+ * It is required to enable direct mode, otherwise control over the chip
+ * select is relinquished to the hardware. SSELOUT is enabled too so we
+ * can deal with active high slaves.
+ */
+ mchp_corespi_write(spi, REG_SLAVE_SELECT, SSELOUT | SSEL_DIRECT);
+
+ control = mchp_corespi_read(spi, REG_CONTROL);
+
+ control &= ~CONTROL_RESET;
+ control |= CONTROL_ENABLE;
+
+ mchp_corespi_write(spi, REG_CONTROL, control);
+}
+
+static inline void mchp_corespi_set_clk_gen(struct mchp_corespi *spi)
+{
+ u32 control;
+
+ mchp_corespi_disable(spi);
+
+ control = mchp_corespi_read(spi, REG_CONTROL);
+ if (spi->clk_mode)
+ control |= CONTROL_CLKMODE;
+ else
+ control &= ~CONTROL_CLKMODE;
+
+ mchp_corespi_write(spi, REG_CLK_GEN, spi->clk_gen);
+ mchp_corespi_write(spi, REG_CONTROL, control);
+ mchp_corespi_write(spi, REG_CONTROL, control | CONTROL_ENABLE);
+}
+
+static inline void mchp_corespi_set_mode(struct mchp_corespi *spi, unsigned int mode)
+{
+ u32 control, mode_val;
+
+ switch (mode & SPI_MODE_X_MASK) {
+ case SPI_MODE_0:
+ mode_val = 0;
+ break;
+ case SPI_MODE_1:
+ mode_val = CONTROL_SPH;
+ break;
+ case SPI_MODE_2:
+ mode_val = CONTROL_SPO;
+ break;
+ case SPI_MODE_3:
+ mode_val = CONTROL_SPH | CONTROL_SPO;
+ break;
+ }
+
+ /*
+ * Disable the SPI controller. Writes to the frame size have
+ * no effect when the controller is enabled.
+ */
+ mchp_corespi_disable(spi);
+
+ control = mchp_corespi_read(spi, REG_CONTROL);
+ control &= ~(SPI_MODE_X_MASK << MODE_X_MASK_SHIFT);
+ control |= mode_val;
+
+ mchp_corespi_write(spi, REG_CONTROL, control);
+
+ control |= CONTROL_ENABLE;
+ mchp_corespi_write(spi, REG_CONTROL, control);
+}
+
+static irqreturn_t mchp_corespi_interrupt(int irq, void *dev_id)
+{
+ struct spi_master *master = dev_id;
+ struct mchp_corespi *spi = spi_master_get_devdata(master);
+ u32 intfield = mchp_corespi_read(spi, REG_MIS) & 0xf;
+ bool finalise = false;
+
+ /* Interrupt line may be shared and not for us at all */
+ if (intfield == 0)
+ return IRQ_NONE;
+
+ if (intfield & INT_TXDONE) {
+ mchp_corespi_write(spi, REG_INT_CLEAR, INT_TXDONE);
+
+ if (spi->rx_len)
+ mchp_corespi_read_fifo(spi);
+
+ if (spi->tx_len)
+ mchp_corespi_write_fifo(spi);
+
+ if (!spi->rx_len)
+ finalise = true;
+ }
+
+ if (intfield & INT_RXRDY)
+ mchp_corespi_write(spi, REG_INT_CLEAR, INT_RXRDY);
+
+ if (intfield & INT_RX_CHANNEL_OVERFLOW) {
+ mchp_corespi_write(spi, REG_INT_CLEAR, INT_RX_CHANNEL_OVERFLOW);
+ finalise = true;
+ dev_err(&master->dev,
+ "%s: RX OVERFLOW: rxlen: %d, txlen: %d\n", __func__,
+ spi->rx_len, spi->tx_len);
+ }
+
+ if (intfield & INT_TX_CHANNEL_UNDERRUN) {
+ mchp_corespi_write(spi, REG_INT_CLEAR, INT_TX_CHANNEL_UNDERRUN);
+ finalise = true;
+ dev_err(&master->dev,
+ "%s: TX UNDERFLOW: rxlen: %d, txlen: %d\n", __func__,
+ spi->rx_len, spi->tx_len);
+ }
+
+ if (finalise)
+ spi_finalize_current_transfer(master);
+
+ return IRQ_HANDLED;
+}
+
+static int mchp_corespi_calculate_clkgen(struct mchp_corespi *spi,
+ unsigned long target_hz)
+{
+ unsigned long clk_hz, spi_hz, clk_gen;
+
+ clk_hz = clk_get_rate(spi->clk);
+ spi_hz = min(target_hz, clk_hz);
+
+ /*
+ * There are two possible clock modes for the controller generated
+ * clock's division ratio:
+ * CLK_MODE = 0: 1 / (2^(CLK_GEN + 1)) where CLK_GEN = 0 to 15.
+ * CLK_MODE = 1: 1 / (2 * CLK_GEN + 1) where CLK_GEN = 0 to 255.
+ * First try mode 1, fall back to 0 and if we have tried both modes and
+ * we /still/ can't get a good setting, we then throw the toys out of
+ * the pram and give up
+ * clk_gen is the register name for the clock divider on MPFS.
+ */
+ clk_gen = DIV_ROUND_UP(clk_hz, 2 * spi_hz) - 1;
+ if (clk_gen > CLK_GEN_MODE1_MAX || clk_gen <= CLK_GEN_MIN) {
+ clk_gen = DIV_ROUND_UP(clk_hz, spi_hz);
+ clk_gen = fls(clk_gen) - 1;
+
+ if (clk_gen > CLK_GEN_MODE0_MAX)
+ return -EINVAL;
+
+ spi->clk_mode = 0;
+ } else {
+ spi->clk_mode = 1;
+ }
+
+ spi->clk_gen = clk_gen;
+ return 0;
+}
+
+static int mchp_corespi_transfer_one(struct spi_master *master,
+ struct spi_device *spi_dev,
+ struct spi_transfer *xfer)
+{
+ struct mchp_corespi *spi = spi_master_get_devdata(master);
+ int ret;
+
+ ret = mchp_corespi_calculate_clkgen(spi, (unsigned long)xfer->speed_hz);
+ if (ret) {
+ dev_err(&master->dev, "failed to set clk_gen for target %u Hz\n", xfer->speed_hz);
+ return ret;
+ }
+
+ mchp_corespi_set_clk_gen(spi);
+
+ spi->tx_buf = xfer->tx_buf;
+ spi->rx_buf = xfer->rx_buf;
+ spi->tx_len = xfer->len;
+ spi->rx_len = xfer->len;
+ spi->pending = 0;
+
+ mchp_corespi_set_xfer_size(spi, (spi->tx_len > FIFO_DEPTH)
+ ? FIFO_DEPTH : spi->tx_len);
+
+ if (spi->tx_len)
+ mchp_corespi_write_fifo(spi);
+ return 1;
+}
+
+static int mchp_corespi_prepare_message(struct spi_master *master,
+ struct spi_message *msg)
+{
+ struct spi_device *spi_dev = msg->spi;
+ struct mchp_corespi *spi = spi_master_get_devdata(master);
+
+ mchp_corespi_set_framesize(spi, DEFAULT_FRAMESIZE);
+ mchp_corespi_set_mode(spi, spi_dev->mode);
+
+ return 0;
+}
+
+static int mchp_corespi_probe(struct platform_device *pdev)
+{
+ struct spi_master *master;
+ struct mchp_corespi *spi;
+ struct resource *res;
+ u32 num_cs;
+ int ret = 0;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(*spi));
+ if (!master)
+ return dev_err_probe(&pdev->dev, -ENOMEM,
+ "unable to allocate master for SPI controller\n");
+
+ platform_set_drvdata(pdev, master);
+
+ if (of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs))
+ num_cs = MAX_CS;
+
+ master->num_chipselect = num_cs;
+ master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+ master->setup = mchp_corespi_setup;
+ master->bits_per_word_mask = SPI_BPW_MASK(8);
+ master->transfer_one = mchp_corespi_transfer_one;
+ master->prepare_message = mchp_corespi_prepare_message;
+ master->set_cs = mchp_corespi_set_cs;
+ master->dev.of_node = pdev->dev.of_node;
+
+ spi = spi_master_get_devdata(master);
+
+ spi->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+ if (IS_ERR(spi->regs)) {
+ ret = PTR_ERR(spi->regs);
+ goto error_release_master;
+ }
+
+ spi->irq = platform_get_irq(pdev, 0);
+ if (spi->irq <= 0) {
+ dev_err(&pdev->dev, "invalid IRQ %d for SPI controller\n", spi->irq);
+ ret = spi->irq;
+ goto error_release_master;
+ }
+
+ ret = devm_request_irq(&pdev->dev, spi->irq, mchp_corespi_interrupt,
+ IRQF_SHARED, dev_name(&pdev->dev), master);
+ if (ret) {
+ dev_err(&pdev->dev, "could not request irq: %d\n", ret);
+ goto error_release_master;
+ }
+
+ spi->clk = devm_clk_get(&pdev->dev, NULL);
+ if (!spi->clk || IS_ERR(spi->clk)) {
+ ret = PTR_ERR(spi->clk);
+ dev_err(&pdev->dev, "could not get clk: %d\n", ret);
+ goto error_release_master;
+ }
+
+ ret = clk_prepare_enable(spi->clk);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to enable clock\n");
+ goto error_release_master;
+ }
+
+ mchp_corespi_init(master, spi);
+
+ ret = devm_spi_register_master(&pdev->dev, master);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "unable to register master for SPI controller\n");
+ goto error_release_hardware;
+ }
+
+ dev_info(&pdev->dev, "Registered SPI controller %d\n", master->bus_num);
+
+ return 0;
+
+error_release_hardware:
+ mchp_corespi_disable(spi);
+ clk_prepare_enable(spi->clk);
+error_release_master:
+ spi_master_put(master);
+
+ return ret;
+}
+
+static int mchp_corespi_remove(struct platform_device *pdev)
+{
+ struct spi_master *master = platform_get_drvdata(pdev);
+ struct mchp_corespi *spi = spi_master_get_devdata(master);
+
+ mchp_corespi_disable_ints(spi);
+ spi_unregister_master(master);
+ spi_master_put(master);
+ clk_disable_unprepare(spi->clk);
+ mchp_corespi_disable(spi);
+
+ return 0;
+}
+
+#define MICROCHIP_SPI_PM_OPS (NULL)
+
+/*
+ * Platform driver data structure
+ */
+
+#if defined(CONFIG_OF)
+static const struct of_device_id mchp_corespi_dt_ids[] = {
+ { .compatible = "microchip,mpfs-spi" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mchp_corespi_dt_ids);
+#endif
+
+static struct platform_driver mchp_corespi_driver = {
+ .probe = mchp_corespi_probe,
+ .driver = {
+ .name = "microchip-corespi",
+ .pm = MICROCHIP_SPI_PM_OPS,
+ .of_match_table = of_match_ptr(mchp_corespi_dt_ids),
+ .owner = THIS_MODULE,
+ },
+ .remove = mchp_corespi_remove,
+};
+module_platform_driver(mchp_corespi_driver);
+MODULE_DESCRIPTION("Microchip coreSPI SPI controller driver");
+MODULE_AUTHOR("Daire McNamara <daire.mcnamara@microchip.com>");
+MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
+MODULE_LICENSE("GPL");
projects / platform / kernel / linux-rpi.git / commitdiff