blob: c1fc290bd253e8d87ba1e01a4c0b74e7a7eebeae [file] [log] [blame]
/*
* (C) Copyright 2015, Samsung Electronics
* Przemyslaw Marczak <p.marczak@samsung.com>
*
* This file is based on: drivers/i2c/soft-i2c.c,
* with added driver-model support and code cleanup.
*/
#include <common.h>
#include <errno.h>
#include <dm.h>
#include <i2c.h>
#include <log.h>
#include <asm/gpio.h>
#include <linux/delay.h>
#define DEFAULT_UDELAY 5
#define RETRIES 0
#define I2C_ACK 0
#define I2C_NOACK 1
enum {
PIN_SDA = 0,
PIN_SCL,
PIN_COUNT,
};
struct i2c_gpio_bus {
/**
* udelay - delay [us] between GPIO toggle operations,
* which is 1/4 of I2C speed clock period.
*/
int udelay;
/* sda, scl */
struct gpio_desc gpios[PIN_COUNT];
int (*get_sda)(struct i2c_gpio_bus *bus);
void (*set_sda)(struct i2c_gpio_bus *bus, int bit);
void (*set_scl)(struct i2c_gpio_bus *bus, int bit);
};
static int i2c_gpio_sda_get(struct i2c_gpio_bus *bus)
{
struct gpio_desc *sda = &bus->gpios[PIN_SDA];
return dm_gpio_get_value(sda);
}
static void i2c_gpio_sda_set(struct i2c_gpio_bus *bus, int bit)
{
struct gpio_desc *sda = &bus->gpios[PIN_SDA];
ulong flags;
if (bit)
flags = GPIOD_IS_IN;
else
flags = GPIOD_IS_OUT;
dm_gpio_clrset_flags(sda, GPIOD_MASK_DIR, flags);
}
static void i2c_gpio_scl_set(struct i2c_gpio_bus *bus, int bit)
{
struct gpio_desc *scl = &bus->gpios[PIN_SCL];
int count = 0;
if (bit) {
dm_gpio_clrset_flags(scl, GPIOD_MASK_DIR, GPIOD_IS_IN);
while (!dm_gpio_get_value(scl) && count++ < 100000)
udelay(1);
if (!dm_gpio_get_value(scl))
pr_err("timeout waiting on slave to release scl\n");
} else {
dm_gpio_clrset_flags(scl, GPIOD_MASK_DIR, GPIOD_IS_OUT);
}
}
/* variant for output only gpios which cannot support clock stretching */
static void i2c_gpio_scl_set_output_only(struct i2c_gpio_bus *bus, int bit)
{
struct gpio_desc *scl = &bus->gpios[PIN_SCL];
ulong flags = GPIOD_IS_OUT;
if (bit)
flags |= GPIOD_IS_OUT_ACTIVE;
dm_gpio_clrset_flags(scl, GPIOD_MASK_DIR, flags);
}
static void i2c_gpio_write_bit(struct i2c_gpio_bus *bus, int delay, uchar bit)
{
bus->set_scl(bus, 0);
udelay(delay);
bus->set_sda(bus, bit);
udelay(delay);
bus->set_scl(bus, 1);
udelay(2 * delay);
}
static int i2c_gpio_read_bit(struct i2c_gpio_bus *bus, int delay)
{
int value;
bus->set_scl(bus, 1);
udelay(delay);
value = bus->get_sda(bus);
udelay(delay);
bus->set_scl(bus, 0);
udelay(2 * delay);
return value;
}
/* START: High -> Low on SDA while SCL is High */
static void i2c_gpio_send_start(struct i2c_gpio_bus *bus, int delay)
{
udelay(delay);
bus->set_sda(bus, 1);
udelay(delay);
bus->set_scl(bus, 1);
udelay(delay);
bus->set_sda(bus, 0);
udelay(delay);
}
/* STOP: Low -> High on SDA while SCL is High */
static void i2c_gpio_send_stop(struct i2c_gpio_bus *bus, int delay)
{
bus->set_scl(bus, 0);
udelay(delay);
bus->set_sda(bus, 0);
udelay(delay);
bus->set_scl(bus, 1);
udelay(delay);
bus->set_sda(bus, 1);
udelay(delay);
}
/* ack should be I2C_ACK or I2C_NOACK */
static void i2c_gpio_send_ack(struct i2c_gpio_bus *bus, int delay, int ack)
{
i2c_gpio_write_bit(bus, delay, ack);
bus->set_scl(bus, 0);
udelay(delay);
}
/**
* Send a reset sequence consisting of 9 clocks with the data signal high
* to clock any confused device back into an idle state. Also send a
* <stop> at the end of the sequence for belts & suspenders.
*/
static void i2c_gpio_send_reset(struct i2c_gpio_bus *bus, int delay)
{
int j;
for (j = 0; j < 9; j++)
i2c_gpio_write_bit(bus, delay, 1);
i2c_gpio_send_stop(bus, delay);
}
/* Set sda high with low clock, before reading slave data */
static void i2c_gpio_sda_high(struct i2c_gpio_bus *bus, int delay)
{
bus->set_scl(bus, 0);
udelay(delay);
bus->set_sda(bus, 1);
udelay(delay);
}
/* Send 8 bits and look for an acknowledgement */
static int i2c_gpio_write_byte(struct i2c_gpio_bus *bus, int delay, uchar data)
{
int j;
int nack;
for (j = 0; j < 8; j++) {
i2c_gpio_write_bit(bus, delay, data & 0x80);
data <<= 1;
}
udelay(delay);
/* Look for an <ACK>(negative logic) and return it */
i2c_gpio_sda_high(bus, delay);
nack = i2c_gpio_read_bit(bus, delay);
return nack; /* not a nack is an ack */
}
/**
* if ack == I2C_ACK, ACK the byte so can continue reading, else
* send I2C_NOACK to end the read.
*/
static uchar i2c_gpio_read_byte(struct i2c_gpio_bus *bus, int delay, int ack)
{
int data;
int j;
i2c_gpio_sda_high(bus, delay);
data = 0;
for (j = 0; j < 8; j++) {
data <<= 1;
data |= i2c_gpio_read_bit(bus, delay);
}
i2c_gpio_send_ack(bus, delay, ack);
return data;
}
/* send start and the slave chip address */
int i2c_send_slave_addr(struct i2c_gpio_bus *bus, int delay, uchar chip)
{
i2c_gpio_send_start(bus, delay);
if (i2c_gpio_write_byte(bus, delay, chip)) {
i2c_gpio_send_stop(bus, delay);
return -EIO;
}
return 0;
}
static int i2c_gpio_write_data(struct i2c_gpio_bus *bus, uchar chip,
uchar *buffer, int len,
bool end_with_repeated_start)
{
unsigned int delay = bus->udelay;
int failures = 0;
debug("%s: chip %x buffer %p len %d\n", __func__, chip, buffer, len);
if (i2c_send_slave_addr(bus, delay, chip << 1)) {
debug("i2c_write, no chip responded %02X\n", chip);
return -EIO;
}
while (len-- > 0) {
if (i2c_gpio_write_byte(bus, delay, *buffer++))
failures++;
}
if (!end_with_repeated_start) {
i2c_gpio_send_stop(bus, delay);
return failures;
}
if (i2c_send_slave_addr(bus, delay, (chip << 1) | 0x1)) {
debug("i2c_write, no chip responded %02X\n", chip);
return -EIO;
}
return failures;
}
static int i2c_gpio_read_data(struct i2c_gpio_bus *bus, uchar chip,
uchar *buffer, int len)
{
unsigned int delay = bus->udelay;
debug("%s: chip %x buffer: %p len %d\n", __func__, chip, buffer, len);
while (len-- > 0)
*buffer++ = i2c_gpio_read_byte(bus, delay, len == 0);
i2c_gpio_send_stop(bus, delay);
return 0;
}
static int i2c_gpio_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
{
struct i2c_gpio_bus *bus = dev_get_priv(dev);
int ret;
for (; nmsgs > 0; nmsgs--, msg++) {
bool next_is_read = nmsgs > 1 && (msg[1].flags & I2C_M_RD);
if (msg->flags & I2C_M_RD) {
ret = i2c_gpio_read_data(bus, msg->addr, msg->buf,
msg->len);
} else {
ret = i2c_gpio_write_data(bus, msg->addr, msg->buf,
msg->len, next_is_read);
}
if (ret)
return -EREMOTEIO;
}
return 0;
}
static int i2c_gpio_probe(struct udevice *dev, uint chip, uint chip_flags)
{
struct i2c_gpio_bus *bus = dev_get_priv(dev);
unsigned int delay = bus->udelay;
int ret;
i2c_gpio_send_start(bus, delay);
ret = i2c_gpio_write_byte(bus, delay, (chip << 1) | 0);
i2c_gpio_send_stop(bus, delay);
debug("%s: bus: %d (%s) chip: %x flags: %x ret: %d\n",
__func__, dev_seq(dev), dev->name, chip, chip_flags, ret);
return ret;
}
static int i2c_gpio_set_bus_speed(struct udevice *dev, unsigned int speed_hz)
{
struct i2c_gpio_bus *bus = dev_get_priv(dev);
bus->udelay = 1000000 / (speed_hz << 2);
i2c_gpio_send_reset(bus, bus->udelay);
return 0;
}
static int i2c_gpio_drv_probe(struct udevice *dev)
{
if (dev_read_bool(dev, "i2c-gpio,deblock")) {
/* @200kHz 9 clocks = 44us, 62us is ok */
const unsigned int DELAY_ABORT_SEQ = 62;
struct i2c_gpio_bus *bus = dev_get_priv(dev);
return i2c_deblock_gpio_loop(&bus->gpios[PIN_SDA],
&bus->gpios[PIN_SCL],
16, 5, DELAY_ABORT_SEQ);
}
return 0;
}
static int i2c_gpio_of_to_plat(struct udevice *dev)
{
struct i2c_gpio_bus *bus = dev_get_priv(dev);
int ret;
/* "gpios" is deprecated and replaced by "sda-gpios" + "scl-gpios". */
ret = gpio_request_list_by_name(dev, "gpios", bus->gpios,
ARRAY_SIZE(bus->gpios), 0);
if (ret == 0) {
ret = gpio_request_by_name(dev, "sda-gpios", 0,
&bus->gpios[PIN_SDA], 0);
if (ret < 0)
goto error;
ret = gpio_request_by_name(dev, "scl-gpios", 0,
&bus->gpios[PIN_SCL], 0);
}
if (ret < 0)
goto error;
bus->udelay = dev_read_u32_default(dev, "i2c-gpio,delay-us",
DEFAULT_UDELAY);
bus->get_sda = i2c_gpio_sda_get;
bus->set_sda = i2c_gpio_sda_set;
if (dev_read_bool(dev, "i2c-gpio,scl-output-only"))
bus->set_scl = i2c_gpio_scl_set_output_only;
else
bus->set_scl = i2c_gpio_scl_set;
return 0;
error:
pr_err("Can't get %s gpios! Error: %d\n", dev->name, ret);
return ret;
}
static const struct dm_i2c_ops i2c_gpio_ops = {
.xfer = i2c_gpio_xfer,
.probe_chip = i2c_gpio_probe,
.set_bus_speed = i2c_gpio_set_bus_speed,
};
static const struct udevice_id i2c_gpio_ids[] = {
{ .compatible = "i2c-gpio" },
{ }
};
U_BOOT_DRIVER(i2c_gpio) = {
.name = "i2c-gpio",
.id = UCLASS_I2C,
.of_match = i2c_gpio_ids,
.probe = i2c_gpio_drv_probe,
.of_to_plat = i2c_gpio_of_to_plat,
.priv_auto = sizeof(struct i2c_gpio_bus),
.ops = &i2c_gpio_ops,
};