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|
/*
* Bitbanging I2C bus driver using the GPIO API
*
* Copyright (C) 2007 Atmel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <linux/platform_data/i2c-gpio.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>
struct i2c_gpio_private_data {
struct gpio_desc *sda;
struct gpio_desc *scl;
struct i2c_adapter adap;
struct i2c_algo_bit_data bit_data;
struct i2c_gpio_platform_data pdata;
#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
struct dentry *debug_dir;
#endif
};
/*
* Toggle SDA by changing the output value of the pin. This is only
* valid for pins configured as open drain (i.e. setting the value
* high effectively turns off the output driver.)
*/
static void i2c_gpio_setsda_val(void *data, int state)
{
struct i2c_gpio_private_data *priv = data;
gpiod_set_value_cansleep(priv->sda, state);
}
/*
* Toggle SCL by changing the output value of the pin. This is used
* for pins that are configured as open drain and for output-only
* pins. The latter case will break the i2c protocol, but it will
* often work in practice.
*/
static void i2c_gpio_setscl_val(void *data, int state)
{
struct i2c_gpio_private_data *priv = data;
gpiod_set_value_cansleep(priv->scl, state);
}
static int i2c_gpio_getsda(void *data)
{
struct i2c_gpio_private_data *priv = data;
return gpiod_get_value_cansleep(priv->sda);
}
static int i2c_gpio_getscl(void *data)
{
struct i2c_gpio_private_data *priv = data;
return gpiod_get_value_cansleep(priv->scl);
}
#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
static struct dentry *i2c_gpio_debug_dir;
#define setsda(bd, val) ((bd)->setsda((bd)->data, val))
#define setscl(bd, val) ((bd)->setscl((bd)->data, val))
#define getsda(bd) ((bd)->getsda((bd)->data))
#define getscl(bd) ((bd)->getscl((bd)->data))
#define WIRE_ATTRIBUTE(wire) \
static int fops_##wire##_get(void *data, u64 *val) \
{ \
struct i2c_gpio_private_data *priv = data; \
\
i2c_lock_adapter(&priv->adap); \
*val = get##wire(&priv->bit_data); \
i2c_unlock_adapter(&priv->adap); \
return 0; \
} \
static int fops_##wire##_set(void *data, u64 val) \
{ \
struct i2c_gpio_private_data *priv = data; \
\
i2c_lock_adapter(&priv->adap); \
set##wire(&priv->bit_data, val); \
i2c_unlock_adapter(&priv->adap); \
return 0; \
} \
DEFINE_DEBUGFS_ATTRIBUTE(fops_##wire, fops_##wire##_get, fops_##wire##_set, "%llu\n")
WIRE_ATTRIBUTE(scl);
WIRE_ATTRIBUTE(sda);
static void i2c_gpio_incomplete_transfer(struct i2c_gpio_private_data *priv,
u32 pattern, u8 pattern_size)
{
struct i2c_algo_bit_data *bit_data = &priv->bit_data;
int i;
i2c_lock_adapter(&priv->adap);
/* START condition */
setsda(bit_data, 0);
udelay(bit_data->udelay);
/* Send pattern, request ACK, don't send STOP */
for (i = pattern_size - 1; i >= 0; i--) {
setscl(bit_data, 0);
udelay(bit_data->udelay / 2);
setsda(bit_data, (pattern >> i) & 1);
udelay((bit_data->udelay + 1) / 2);
setscl(bit_data, 1);
udelay(bit_data->udelay);
}
i2c_unlock_adapter(&priv->adap);
}
static int fops_incomplete_addr_phase_set(void *data, u64 addr)
{
struct i2c_gpio_private_data *priv = data;
u32 pattern;
if (addr > 0x7f)
return -EINVAL;
/* ADDR (7 bit) + RD (1 bit) + Client ACK, keep SDA hi (1 bit) */
pattern = (addr << 2) | 3;
i2c_gpio_incomplete_transfer(priv, pattern, 9);
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_addr_phase, NULL, fops_incomplete_addr_phase_set, "%llu\n");
static int fops_incomplete_write_byte_set(void *data, u64 addr)
{
struct i2c_gpio_private_data *priv = data;
u32 pattern;
if (addr > 0x7f)
return -EINVAL;
/* ADDR (7 bit) + WR (1 bit) + Client ACK (1 bit) */
pattern = (addr << 2) | 1;
/* 0x00 (8 bit) + Client ACK, keep SDA hi (1 bit) */
pattern = (pattern << 9) | 1;
i2c_gpio_incomplete_transfer(priv, pattern, 18);
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_write_byte, NULL, fops_incomplete_write_byte_set, "%llu\n");
static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
/*
* If there will be a debugfs-dir per i2c adapter somewhen, put the
* 'fault-injector' dir there. Until then, we have a global dir with
* all adapters as subdirs.
*/
if (!i2c_gpio_debug_dir) {
i2c_gpio_debug_dir = debugfs_create_dir("i2c-fault-injector", NULL);
if (!i2c_gpio_debug_dir)
return;
}
priv->debug_dir = debugfs_create_dir(pdev->name, i2c_gpio_debug_dir);
if (!priv->debug_dir)
return;
debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl);
debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda);
debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->debug_dir,
priv, &fops_incomplete_addr_phase);
debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->debug_dir,
priv, &fops_incomplete_write_byte);
}
static void i2c_gpio_fault_injector_exit(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
debugfs_remove_recursive(priv->debug_dir);
}
#else
static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
static inline void i2c_gpio_fault_injector_exit(struct platform_device *pdev) {}
#endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/
static void of_i2c_gpio_get_props(struct device_node *np,
struct i2c_gpio_platform_data *pdata)
{
u32 reg;
of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", ®))
pdata->timeout = msecs_to_jiffies(reg);
pdata->sda_is_open_drain =
of_property_read_bool(np, "i2c-gpio,sda-open-drain");
pdata->scl_is_open_drain =
of_property_read_bool(np, "i2c-gpio,scl-open-drain");
pdata->scl_is_output_only =
of_property_read_bool(np, "i2c-gpio,scl-output-only");
}
static struct gpio_desc *i2c_gpio_get_desc(struct device *dev,
const char *con_id,
unsigned int index,
enum gpiod_flags gflags)
{
struct gpio_desc *retdesc;
int ret;
retdesc = devm_gpiod_get(dev, con_id, gflags);
if (!IS_ERR(retdesc)) {
dev_dbg(dev, "got GPIO from name %s\n", con_id);
return retdesc;
}
retdesc = devm_gpiod_get_index(dev, NULL, index, gflags);
if (!IS_ERR(retdesc)) {
dev_dbg(dev, "got GPIO from index %u\n", index);
return retdesc;
}
ret = PTR_ERR(retdesc);
/* FIXME: hack in the old code, is this really necessary? */
if (ret == -EINVAL)
retdesc = ERR_PTR(-EPROBE_DEFER);
/* This happens if the GPIO driver is not yet probed, let's defer */
if (ret == -ENOENT)
retdesc = ERR_PTR(-EPROBE_DEFER);
if (ret != -EPROBE_DEFER)
dev_err(dev, "error trying to get descriptor: %d\n", ret);
return retdesc;
}
static int i2c_gpio_probe(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv;
struct i2c_gpio_platform_data *pdata;
struct i2c_algo_bit_data *bit_data;
struct i2c_adapter *adap;
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
enum gpiod_flags gflags;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
adap = &priv->adap;
bit_data = &priv->bit_data;
pdata = &priv->pdata;
if (np) {
of_i2c_gpio_get_props(np, pdata);
} else {
/*
* If all platform data settings are zero it is OK
* to not provide any plat
|