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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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