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- // SPDX-License-Identifier: GPL-2.0+
- /*
- * Copyright (c) 2018 Arm Ltd.
- * Author: Liviu Dudau <liviu.dudau@foss.arm.com>
- *
- */
- #include <common.h>
- #include <dm.h>
- #include <errno.h>
- #include <i2c.h>
- #include <asm/io.h>
- #include <clk.h>
- #include <linux/io.h>
- #define I2C_CONTROL_REG 0x00
- #define I2C_SET_REG 0x00
- #define I2C_CLEAR_REG 0x04
- #define SCL BIT(0)
- #define SDA BIT(1)
- struct versatile_i2c_priv {
- phys_addr_t base;
- u32 delay;
- };
- static inline void versatile_sda_set(struct versatile_i2c_priv *priv, u8 state)
- {
- writel(SDA, priv->base + (state ? I2C_SET_REG : I2C_CLEAR_REG));
- udelay(priv->delay);
- }
- static inline int versatile_sda_get(struct versatile_i2c_priv *priv)
- {
- int v = !!(readl(priv->base + I2C_CONTROL_REG) & SDA);
- udelay(priv->delay);
- return v;
- }
- static inline void versatile_scl_set(struct versatile_i2c_priv *priv, u8 state)
- {
- writel(SCL, priv->base + (state ? I2C_SET_REG : I2C_CLEAR_REG));
- udelay(priv->delay);
- }
- static inline int versatile_scl_get(struct versatile_i2c_priv *priv)
- {
- int v = !!(readl(priv->base + I2C_CONTROL_REG) & SCL);
- udelay(priv->delay);
- return v;
- }
- /* start: SDA goes from high to low while SCL is high */
- static void versatile_i2c_start(struct versatile_i2c_priv *priv)
- {
- udelay(priv->delay);
- versatile_sda_set(priv, 1);
- versatile_scl_set(priv, 1);
- versatile_sda_set(priv, 0);
- }
- /* stop: SDA goes from low to high while SCL is high */
- static void versatile_i2c_stop(struct versatile_i2c_priv *priv)
- {
- versatile_scl_set(priv, 0);
- versatile_sda_set(priv, 0);
- versatile_scl_set(priv, 1);
- versatile_sda_set(priv, 1);
- }
- /* read a bit from the SDA line (data or ACK/NACK) */
- static u8 versatile_i2c_read_bit(struct versatile_i2c_priv *priv)
- {
- versatile_scl_set(priv, 0);
- versatile_sda_set(priv, 1);
- versatile_scl_set(priv, 1);
- udelay(priv->delay);
- return (u8)versatile_sda_get(priv);
- }
- /* write a bit on the SDA line */
- static void versatile_i2c_write_bit(struct versatile_i2c_priv *priv, u8 bit)
- {
- versatile_scl_set(priv, 0);
- versatile_sda_set(priv, bit);
- versatile_scl_set(priv, 1);
- udelay(priv->delay);
- }
- /* send a reset sequence of 9 clocks with SDA high */
- static void versatile_i2c_reset_bus(struct versatile_i2c_priv *priv)
- {
- int i;
- for (i = 0; i < 9; i++)
- versatile_i2c_write_bit(priv, 1);
- versatile_i2c_stop(priv);
- }
- /* write byte without start/stop sequence */
- static int versatile_i2c_write_byte(struct versatile_i2c_priv *priv, u8 byte)
- {
- u8 nak, i;
- for (i = 0; i < 8; i++) {
- versatile_i2c_write_bit(priv, byte & 0x80);
- byte <<= 1;
- }
- /* read ACK */
- nak = versatile_i2c_read_bit(priv);
- versatile_scl_set(priv, 0);
- return nak; /* not a nack is an ack */
- }
- static int versatile_i2c_read_byte(struct versatile_i2c_priv *priv,
- u8 *byte, u8 ack)
- {
- u8 i;
- *byte = 0;
- for (i = 0; i < 8; i++) {
- *byte <<= 1;
- *byte |= versatile_i2c_read_bit(priv);
- }
- /* write the nack */
- versatile_i2c_write_bit(priv, ack);
- return 0;
- }
- static int versatile_i2c_send_slave_addr(struct versatile_i2c_priv *priv,
- struct i2c_msg *msg)
- {
- u8 addr;
- int ret;
- if (msg->flags & I2C_M_TEN) {
- /* 10-bit address, send extended address code first */
- addr = 0xf0 | ((msg->addr >> 7) & 0x06);
- ret = versatile_i2c_write_byte(priv, addr);
- if (ret) {
- versatile_i2c_stop(priv);
- return -EIO;
- }
- /* remaining bits */
- ret = versatile_i2c_write_byte(priv, msg->addr & 0xff);
- if (ret) {
- versatile_i2c_stop(priv);
- return -EIO;
- }
- /* reads need to resend the addr */
- if (msg->flags & I2C_M_RD) {
- versatile_i2c_start(priv);
- addr |= 1;
- ret = versatile_i2c_write_byte(priv, addr);
- if (ret) {
- versatile_i2c_stop(priv);
- return -EIO;
- }
- }
- } else {
- /* normal 7-bit address */
- addr = msg->addr << 1;
- if (msg->flags & I2C_M_RD)
- addr |= 1;
- ret = versatile_i2c_write_byte(priv, addr);
- if (ret) {
- versatile_i2c_stop(priv);
- return -EIO;
- }
- }
- return 0;
- }
- static int versatile_i2c_message_xfer(struct versatile_i2c_priv *priv,
- struct i2c_msg *msg)
- {
- int i, ret;
- u8 ack;
- versatile_i2c_start(priv);
- if (versatile_i2c_send_slave_addr(priv, msg))
- return -EIO;
- for (i = 0; i < msg->len; i++) {
- if (msg->flags & I2C_M_RD) {
- ack = (msg->len - i - 1) == 0 ? 1 : 0;
- ret = versatile_i2c_read_byte(priv, &msg->buf[i], ack);
- } else {
- ret = versatile_i2c_write_byte(priv, msg->buf[i]);
- }
- if (ret)
- break;
- }
- versatile_i2c_stop(priv);
- return ret;
- }
- static int versatile_i2c_xfer(struct udevice *bus,
- struct i2c_msg *msg, int nmsgs)
- {
- struct versatile_i2c_priv *priv = dev_get_priv(bus);
- int ret;
- for ( ; nmsgs > 0; nmsgs--, msg++) {
- ret = versatile_i2c_message_xfer(priv, msg);
- if (ret)
- return -EREMOTEIO;
- }
- return 0;
- }
- static int versatile_i2c_chip_probe(struct udevice *bus,
- uint chip, uint chip_flags)
- {
- /* probe the presence of a slave by writing a 0-size message */
- struct i2c_msg msg = { .addr = chip, .flags = chip_flags,
- .len = 0, .buf = NULL };
- struct versatile_i2c_priv *priv = dev_get_priv(bus);
- return versatile_i2c_message_xfer(priv, &msg);
- }
- static int versatile_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
- {
- struct versatile_i2c_priv *priv = dev_get_priv(bus);
- priv->delay = 1000000 / (speed << 2);
- versatile_i2c_reset_bus(priv);
- return 0;
- }
- static int versatile_i2c_probe(struct udevice *dev)
- {
- struct versatile_i2c_priv *priv = dev_get_priv(dev);
- priv->base = (phys_addr_t)dev_read_addr(dev);
- priv->delay = 25; /* 25us * 4 = 100kHz */
- /*
- * U-Boot still doesn't assign automatically
- * sequence numbers to devices
- */
- dev->req_seq = 1;
- return 0;
- }
- static const struct dm_i2c_ops versatile_i2c_ops = {
- .xfer = versatile_i2c_xfer,
- .probe_chip = versatile_i2c_chip_probe,
- .set_bus_speed = versatile_i2c_set_bus_speed,
- };
- static const struct udevice_id versatile_i2c_of_match[] = {
- { .compatible = "arm,versatile-i2c" },
- { }
- };
- U_BOOT_DRIVER(versatile_i2c) = {
- .name = "i2c-bus-versatile",
- .id = UCLASS_I2C,
- .of_match = versatile_i2c_of_match,
- .probe = versatile_i2c_probe,
- .priv_auto_alloc_size = sizeof(struct versatile_i2c_priv),
- .ops = &versatile_i2c_ops,
- };
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