mirror of
https://github.com/brain-hackers/u-boot-brain
synced 2024-08-27 20:38:52 +09:00
281 lines
6.0 KiB
C
281 lines
6.0 KiB
C
![]() |
// 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,
|
||
|
};
|