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/*
* I2C multiplexer using GPIO API
*
* Peter Korsgaard <peter.korsgaard@barco.com>
*
* 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-mux.h>
#include <linux/i2c-mux-gpio.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/gpio.h>
struct gpiomux {
struct i2c_adapter *parent;
struct i2c_adapter **adap; /* child busses */
struct i2c_mux_gpio_platform_data data;
unsigned gpio_base;
};
static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
{
int i;
for (i = 0; i < mux->data.n_gpios; i++)
gpio_set_value(mux->gpio_base + mux->data.gpios[i],
val & (1 << i));
}
static int i2c_mux_gpio_select(struct i2c_adapter *adap, void *data, u32 chan)
{
struct gpiomux *mux = data;
i2c_mux_gpio_set(mux, mux->data.values[chan]);
return 0;
}
static int i2c_mux_gpio_deselect(struct i2c_adapter *adap, void *data, u32 chan)
{
struct gpiomux *mux = data;
i2c_mux_gpio_set(mux, mux->data.idle);
return 0;
}
static int __devinit match_gpio_chip_by_label(struct gpio_chip *chip,
void *data)
{
return !strcmp(chip->label, data);
}
static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
{
struct gpiomux *mux;
struct i2c_mux_gpio_platform_data *pdata;
struct i2c_adapter *parent;
int (*deselect) (struct i2c_adapter *, void *, u32);
unsigned initial_state, gpio_base;
int i, ret;
pdata = pdev->dev.platform_data;
if (!pdata) {
dev_err(&pdev->dev, "Missing platform data\n");
return -ENODEV;
}
/*
* If a GPIO chip name is provided, the GPIO pin numbers provided are
* relative to its base GPIO number. Otherwise they are absolute.
*/
if (pdata->gpio_chip) {
struct gpio_chip *gpio;
gpio = gpiochip_find(pdata->gpio_chip,
match_gpio_chip_by_label);
if (!gpio)
return -EPROBE_DEFER;
gpio_base = gpio->base;
} else {
gpio_base = 0;
}
parent = i2c_get_adapter(pdata->parent);
if (!parent) {
dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
pdata->parent);
return -ENODEV;
}
mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
if (!mux) {
ret = -ENOMEM;
goto alloc_failed;
}
mux->parent = parent;
mux->data = *pdata;
mux->gpio_base = gpio_base;
mux->adap = devm_kzalloc(&pdev->dev,
sizeof(*mux->adap) * pdata->n_values,
GFP_KERNEL);
if (!mux->adap) {
ret = -ENOMEM;
goto alloc_failed;
}
if (pdata->idle != I2C_MUX_GPIO_NO_IDLE) {
initial_state = pdata->idle;
deselect = i2c_mux_gpio_deselect;
} else {
initial_state = pdata->values[0];
deselect = NULL;
}
for (i = 0; i < pdata->n_gpios; i++) {
ret = gpio_request(gpio_base + pdata->gpios[i], "i2c-mux-gpio");
if (ret)
goto err_request_gpio;
gpio_direction_output(gpio_base + pdata->gpios[i],
initial_state & (1 << i));
}
for (i = 0; i < pdata->n_values; i++) {
u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
unsigned int class = pdata->classes ? pdata->classes[i] : 0;
mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
i, class,
i2c_mux_gpio_select, deselect);
if (!mux->adap[i]) {
ret = -ENODEV;
dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
goto add_adapter_failed;
}
}
dev_info(&pdev->dev, "%d port mux on %s adapter\n",
pdata->n_values, parent->name);
platform_set_drvdata(pdev, mux);
return 0;
add_adapter_failed:
for (; i > 0; i--)
i2c_del_mux_adapter(mux->adap[i - 1]);
i = pdata->n_gpios;
err_request_gpio:
for (; i > 0; i--)
gpio_free(gpio_base + pdata->gpios[i - 1]);
alloc_failed:
i2c_put_adapter(parent);
return ret;
}
static int __devexit i2c_mux_gpio_remove(struct platform_device *pdev)
{
struct gpiomux *mux = platform_get_drvdata(pdev);
int i;
for (i = 0; i < mux->data.n_values; i++)
i2c_del_mux_adapter(mux->adap[i]);
for (i = 0; i < mux->data.n_gpios; i++)
gpio_free(mux->gpio_base + mux->data.gpios[i]);
platform_set_drvdata(pdev, NULL);
i2c_put_adapter(mux->parent);
return 0;
}
static struct platform_driver i2c_mux_gpio_driver = {
.probe = i2c_mux_gpio_probe,
.remove = __devexit_p(i2c_mux_gpio_remove),
.driver = {
.owner = THIS_MODULE,
.name = "i2c-mux-gpio",
},
};
module_platform_driver(i2c_mux_gpio_driver);
MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:i2c-mux-gpio");
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