280 lines
6.7 KiB
C
280 lines
6.7 KiB
C
/*
|
|
* 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/i2c.h>
|
|
#include <linux/i2c-algo-bit.h>
|
|
#include <linux/i2c-gpio.h>
|
|
#include <linux/init.h>
|
|
#include <linux/module.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/gpio.h>
|
|
#include <linux/of_gpio.h>
|
|
#include <linux/of_i2c.h>
|
|
|
|
struct i2c_gpio_private_data {
|
|
struct i2c_adapter adap;
|
|
struct i2c_algo_bit_data bit_data;
|
|
struct i2c_gpio_platform_data pdata;
|
|
};
|
|
|
|
/* Toggle SDA by changing the direction of the pin */
|
|
static void i2c_gpio_setsda_dir(void *data, int state)
|
|
{
|
|
struct i2c_gpio_platform_data *pdata = data;
|
|
|
|
if (state)
|
|
gpio_direction_input(pdata->sda_pin);
|
|
else
|
|
gpio_direction_output(pdata->sda_pin, 0);
|
|
}
|
|
|
|
/*
|
|
* 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_platform_data *pdata = data;
|
|
|
|
gpio_set_value(pdata->sda_pin, state);
|
|
}
|
|
|
|
/* Toggle SCL by changing the direction of the pin. */
|
|
static void i2c_gpio_setscl_dir(void *data, int state)
|
|
{
|
|
struct i2c_gpio_platform_data *pdata = data;
|
|
|
|
if (state)
|
|
gpio_direction_input(pdata->scl_pin);
|
|
else
|
|
gpio_direction_output(pdata->scl_pin, 0);
|
|
}
|
|
|
|
/*
|
|
* 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_platform_data *pdata = data;
|
|
|
|
gpio_set_value(pdata->scl_pin, state);
|
|
}
|
|
|
|
static int i2c_gpio_getsda(void *data)
|
|
{
|
|
struct i2c_gpio_platform_data *pdata = data;
|
|
|
|
return gpio_get_value(pdata->sda_pin);
|
|
}
|
|
|
|
static int i2c_gpio_getscl(void *data)
|
|
{
|
|
struct i2c_gpio_platform_data *pdata = data;
|
|
|
|
return gpio_get_value(pdata->scl_pin);
|
|
}
|
|
|
|
static int __devinit of_i2c_gpio_probe(struct device_node *np,
|
|
struct i2c_gpio_platform_data *pdata)
|
|
{
|
|
u32 reg;
|
|
|
|
if (of_gpio_count(np) < 2)
|
|
return -ENODEV;
|
|
|
|
pdata->sda_pin = of_get_gpio(np, 0);
|
|
pdata->scl_pin = of_get_gpio(np, 1);
|
|
|
|
if (!gpio_is_valid(pdata->sda_pin) || !gpio_is_valid(pdata->scl_pin)) {
|
|
pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
|
|
np->full_name, pdata->sda_pin, pdata->scl_pin);
|
|
return -ENODEV;
|
|
}
|
|
|
|
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");
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __devinit 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;
|
|
int ret;
|
|
|
|
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
|
|
if (!priv)
|
|
return -ENOMEM;
|
|
adap = &priv->adap;
|
|
bit_data = &priv->bit_data;
|
|
pdata = &priv->pdata;
|
|
|
|
if (pdev->dev.of_node) {
|
|
ret = of_i2c_gpio_probe(pdev->dev.of_node, pdata);
|
|
if (ret)
|
|
return ret;
|
|
} else {
|
|
if (!pdev->dev.platform_data)
|
|
return -ENXIO;
|
|
memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata));
|
|
}
|
|
|
|
ret = gpio_request(pdata->sda_pin, "sda");
|
|
if (ret)
|
|
goto err_request_sda;
|
|
ret = gpio_request(pdata->scl_pin, "scl");
|
|
if (ret)
|
|
goto err_request_scl;
|
|
|
|
if (pdata->sda_is_open_drain) {
|
|
gpio_direction_output(pdata->sda_pin, 1);
|
|
bit_data->setsda = i2c_gpio_setsda_val;
|
|
} else {
|
|
gpio_direction_input(pdata->sda_pin);
|
|
bit_data->setsda = i2c_gpio_setsda_dir;
|
|
}
|
|
|
|
if (pdata->scl_is_open_drain || pdata->scl_is_output_only) {
|
|
gpio_direction_output(pdata->scl_pin, 1);
|
|
bit_data->setscl = i2c_gpio_setscl_val;
|
|
} else {
|
|
gpio_direction_input(pdata->scl_pin);
|
|
bit_data->setscl = i2c_gpio_setscl_dir;
|
|
}
|
|
|
|
if (!pdata->scl_is_output_only)
|
|
bit_data->getscl = i2c_gpio_getscl;
|
|
bit_data->getsda = i2c_gpio_getsda;
|
|
|
|
if (pdata->udelay)
|
|
bit_data->udelay = pdata->udelay;
|
|
else if (pdata->scl_is_output_only)
|
|
bit_data->udelay = 50; /* 10 kHz */
|
|
else
|
|
bit_data->udelay = 5; /* 100 kHz */
|
|
|
|
if (pdata->timeout)
|
|
bit_data->timeout = pdata->timeout;
|
|
else
|
|
bit_data->timeout = HZ / 10; /* 100 ms */
|
|
|
|
bit_data->data = pdata;
|
|
|
|
adap->owner = THIS_MODULE;
|
|
snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
|
|
adap->algo_data = bit_data;
|
|
adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
|
|
adap->dev.parent = &pdev->dev;
|
|
adap->dev.of_node = pdev->dev.of_node;
|
|
|
|
/*
|
|
* If "dev->id" is negative we consider it as zero.
|
|
* The reason to do so is to avoid sysfs names that only make
|
|
* sense when there are multiple adapters.
|
|
*/
|
|
adap->nr = (pdev->id != -1) ? pdev->id : 0;
|
|
ret = i2c_bit_add_numbered_bus(adap);
|
|
if (ret)
|
|
goto err_add_bus;
|
|
|
|
of_i2c_register_devices(adap);
|
|
|
|
platform_set_drvdata(pdev, priv);
|
|
|
|
dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
|
|
pdata->sda_pin, pdata->scl_pin,
|
|
pdata->scl_is_output_only
|
|
? ", no clock stretching" : "");
|
|
|
|
return 0;
|
|
|
|
err_add_bus:
|
|
gpio_free(pdata->scl_pin);
|
|
err_request_scl:
|
|
gpio_free(pdata->sda_pin);
|
|
err_request_sda:
|
|
return ret;
|
|
}
|
|
|
|
static int __devexit i2c_gpio_remove(struct platform_device *pdev)
|
|
{
|
|
struct i2c_gpio_private_data *priv;
|
|
struct i2c_gpio_platform_data *pdata;
|
|
struct i2c_adapter *adap;
|
|
|
|
priv = platform_get_drvdata(pdev);
|
|
adap = &priv->adap;
|
|
pdata = &priv->pdata;
|
|
|
|
i2c_del_adapter(adap);
|
|
gpio_free(pdata->scl_pin);
|
|
gpio_free(pdata->sda_pin);
|
|
|
|
return 0;
|
|
}
|
|
|
|
#if defined(CONFIG_OF)
|
|
static const struct of_device_id i2c_gpio_dt_ids[] = {
|
|
{ .compatible = "i2c-gpio", },
|
|
{ /* sentinel */ }
|
|
};
|
|
|
|
MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
|
|
#endif
|
|
|
|
static struct platform_driver i2c_gpio_driver = {
|
|
.driver = {
|
|
.name = "i2c-gpio",
|
|
.owner = THIS_MODULE,
|
|
.of_match_table = of_match_ptr(i2c_gpio_dt_ids),
|
|
},
|
|
.probe = i2c_gpio_probe,
|
|
.remove = __devexit_p(i2c_gpio_remove),
|
|
};
|
|
|
|
static int __init i2c_gpio_init(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = platform_driver_register(&i2c_gpio_driver);
|
|
if (ret)
|
|
printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
|
|
|
|
return ret;
|
|
}
|
|
subsys_initcall(i2c_gpio_init);
|
|
|
|
static void __exit i2c_gpio_exit(void)
|
|
{
|
|
platform_driver_unregister(&i2c_gpio_driver);
|
|
}
|
|
module_exit(i2c_gpio_exit);
|
|
|
|
MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
|
|
MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_ALIAS("platform:i2c-gpio");
|