2 * Copyright (C) 2014 Panasonic Corporation
3 * Copyright (C) 2015-2016 Socionext Inc.
4 * Author: Masahiro Yamada <yamada.masahiro@socionext.com>
6 * SPDX-License-Identifier: GPL-2.0+
11 #include <linux/types.h>
13 #include <linux/sizes.h>
14 #include <linux/errno.h>
18 struct uniphier_i2c_regs {
19 u32 dtrm; /* data transmission */
20 #define I2C_DTRM_STA (1 << 10)
21 #define I2C_DTRM_STO (1 << 9)
22 #define I2C_DTRM_NACK (1 << 8)
23 #define I2C_DTRM_RD (1 << 0)
24 u32 drec; /* data reception */
25 #define I2C_DREC_STS (1 << 12)
26 #define I2C_DREC_LRB (1 << 11)
27 #define I2C_DREC_LAB (1 << 9)
28 u32 myad; /* slave address */
29 u32 clk; /* clock frequency control */
30 u32 brst; /* bus reset */
31 #define I2C_BRST_FOEN (1 << 1)
32 #define I2C_BRST_BRST (1 << 0)
33 u32 hold; /* hold time control */
34 u32 bsts; /* bus status monitor */
35 u32 noise; /* noise filter control */
36 u32 setup; /* setup time control */
39 #define IOBUS_FREQ 100000000
41 struct uniphier_i2c_dev {
42 struct uniphier_i2c_regs __iomem *regs; /* register base */
43 unsigned long input_clk; /* master clock (Hz) */
44 unsigned long wait_us; /* wait for every byte transfer (us) */
47 static int uniphier_i2c_probe(struct udevice *dev)
50 struct uniphier_i2c_dev *priv = dev_get_priv(dev);
52 addr = devfdt_get_addr(dev);
53 if (addr == FDT_ADDR_T_NONE)
56 priv->regs = devm_ioremap(dev, addr, SZ_64);
60 priv->input_clk = IOBUS_FREQ;
63 writel(0x3, &priv->regs->brst);
68 static int send_and_recv_byte(struct uniphier_i2c_dev *dev, u32 dtrm)
70 writel(dtrm, &dev->regs->dtrm);
73 * This controller only provides interruption to inform the completion
74 * of each byte transfer. (No status register to poll it.)
75 * Unfortunately, U-Boot does not have a good support of interrupt.
80 return readl(&dev->regs->drec);
83 static int send_byte(struct uniphier_i2c_dev *dev, u32 dtrm, bool *stop)
88 drec = send_and_recv_byte(dev, dtrm);
90 if (drec & I2C_DREC_LAB) {
91 debug("uniphier_i2c: bus arbitration failed\n");
95 if (drec & I2C_DREC_LRB) {
96 debug("uniphier_i2c: slave did not return ACK\n");
102 static int uniphier_i2c_transmit(struct uniphier_i2c_dev *dev, uint addr,
103 uint len, const u8 *buf, bool *stop)
107 debug("%s: addr = %x, len = %d\n", __func__, addr, len);
109 ret = send_byte(dev, I2C_DTRM_STA | I2C_DTRM_NACK | addr << 1, stop);
114 ret = send_byte(dev, I2C_DTRM_NACK | *buf++, stop);
121 writel(I2C_DTRM_STO | I2C_DTRM_NACK, &dev->regs->dtrm);
126 static int uniphier_i2c_receive(struct uniphier_i2c_dev *dev, uint addr,
127 uint len, u8 *buf, bool *stop)
131 debug("%s: addr = %x, len = %d\n", __func__, addr, len);
133 ret = send_byte(dev, I2C_DTRM_STA | I2C_DTRM_NACK |
134 I2C_DTRM_RD | addr << 1, stop);
139 *buf++ = send_and_recv_byte(dev, len ? 0 : I2C_DTRM_NACK);
143 writel(I2C_DTRM_STO | I2C_DTRM_NACK, &dev->regs->dtrm);
148 static int uniphier_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
152 struct uniphier_i2c_dev *dev = dev_get_priv(bus);
155 for (; nmsgs > 0; nmsgs--, msg++) {
156 /* If next message is read, skip the stop condition */
157 stop = nmsgs > 1 && msg[1].flags & I2C_M_RD ? false : true;
159 if (msg->flags & I2C_M_RD)
160 ret = uniphier_i2c_receive(dev, msg->addr, msg->len,
163 ret = uniphier_i2c_transmit(dev, msg->addr, msg->len,
173 static int uniphier_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
175 struct uniphier_i2c_dev *priv = dev_get_priv(bus);
177 /* max supported frequency is 400 kHz */
181 /* bus reset: make sure the bus is idle when change the frequency */
182 writel(0x1, &priv->regs->brst);
184 writel((priv->input_clk / speed / 2 << 16) | (priv->input_clk / speed),
187 writel(0x3, &priv->regs->brst);
190 * Theoretically, each byte can be transferred in
191 * 1000000 * 9 / speed usec. For safety, wait more than double.
193 priv->wait_us = 20000000 / speed;
199 static const struct dm_i2c_ops uniphier_i2c_ops = {
200 .xfer = uniphier_i2c_xfer,
201 .set_bus_speed = uniphier_i2c_set_bus_speed,
204 static const struct udevice_id uniphier_i2c_of_match[] = {
205 { .compatible = "socionext,uniphier-i2c" },
209 U_BOOT_DRIVER(uniphier_i2c) = {
210 .name = "uniphier-i2c",
212 .of_match = uniphier_i2c_of_match,
213 .probe = uniphier_i2c_probe,
214 .priv_auto_alloc_size = sizeof(struct uniphier_i2c_dev),
215 .ops = &uniphier_i2c_ops,