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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/module.h>
#include <linux/slab.h>
#include <linux/gpio.h>
#include "../../gpio/gpiolib.h"
#include <linux/of_gpio.h>
struct gpiomux {
struct i2c_mux_gpio_platform_data data;
unsigned gpio_base;
struct gpio_desc **gpios;
int *values;
};
static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
{
int i;
for (i = 0; i < mux->data.n_gpios; i++)
mux->values[i] = (val >> i) & 1;
gpiod_set_array_value_cansleep(mux->data.n_gpios,
mux->gpios, mux->values);
}
static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
{
struct gpiomux *mux = i2c_mux_priv(muxc);
i2c_mux_gpio_set(mux, chan);
return 0;
}
static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
{
struct gpiomux *mux = i2c_mux_priv(muxc);
i2c_mux_gpio_set(mux, mux->data.idle);
return 0;
}
static int match_gpio_chip_by_label(struct gpio_chip *chip,
void *data)
{
return !strcmp(chip->label, data);
}
#ifdef CONFIG_OF
static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct device_node *adapter_np, *child;
struct i2c_adapter *adapter;
unsigned *values, *gpios;
int i = 0, ret;
if (!np)
return -ENODEV;
adapter_np = of_parse_phandle(np, "i2c-parent", 0);
if (!adapter_np) {
dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
return -ENODEV;
}
adapter = of_find_i2c_adapter_by_node(adapter_np);
of_node_put(adapter_np);
if (!adapter)
return -EPROBE_DEFER;
mux->data.parent = i2c_adapter_id(adapter);
put_device(&adapter->dev);
mux->data.n_values = of_get_child_count(np);
values = devm_kcalloc(&pdev->dev,
mux->data.n_values, sizeof(*mux->data.values),
GFP_KERNEL);
if (!values) {
dev_err(&pdev->dev, "Cannot allocate values array");
return -ENOMEM;
}
for_each_child_of_node(np, child) {
of_property_read_u32(child, "reg", values + i);
i++;
}
mux->data.values = values;
if (of_property_read_u32(np, "idle-state", &mux->data.idle))
mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
if (mux->data.n_gpios < 0) {
dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
return -EINVAL;
}
gpios = devm_kcalloc(&pdev->dev,
mux->data.n_gpios, sizeof(*mux->data.gpios),
GFP_KERNEL);
if (!gpios) {
dev_err(&pdev->dev, "Cannot allocate gpios array");
return -ENOMEM;
}
for (i = 0; i < mux->data.n_gpios; i++) {
ret = of_get_named_gpio(np, "mux-gpios", i);
if (ret < 0)
return ret;
gpios[i] = ret;
}
mux->data.gpios = gpios;
return 0;
}
#else
static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
struct platform_device *pdev)
{
return 0;
}
#endif
static int i2c_mux_gpio_probe(struct platform_device *pdev)
{
struct i2c_mux_core *muxc;
struct gpiomux *mux;
struct i2c_adapter *parent;
struct i2c_adapter *root;
unsigned initial_state, gpio_base;
int i, ret;
mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
if (!mux)
return -ENOMEM;
if (!dev_get_platdata(&pdev->dev)) {
ret = i2c_mux_gpio_probe_dt(mux, pdev);
if (ret < 0)
return ret;
} else {
memcpy(&mux->data, dev_get_platdata(&pdev->dev),
sizeof(mux->data));
}
/*
* If a GPIO chip name is provided, the GPIO pin numbers provided are
* relative to its base GPIO number. Otherwise they are absolute.
*/
if (mux->data.gpio_chip) {
struct gpio_chip *gpio;
gpio = gpiochip_find(mux->data.gpio_chip,
match_gpio_chip_by_label);
if (!gpio)
return -EPROBE_DEFER;
gpio_base = gpio->base;
} else {
gpio_base = 0;
}
parent = i2c_get_adapter(mux->data.parent);
if (!parent)
return -EPROBE_DEFER;
muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
mux->data.n_gpios * sizeof(*mux->gpios) +
mux->data.n_gpios * sizeof(*mux->values), 0,
i2c_mux_gpio_select, NULL);
if (!muxc) {
ret = -ENOMEM;
goto alloc_failed;
}
mux->gpios = muxc->priv;
mux->values = (int *)(mux->gpios + mux->data.n_gpios);
muxc->priv = mux;
platform_set_drvdata(pdev, muxc);
root = i2c_root_adapter(&parent->dev);
muxc->mux_locked = true;
mux->gpio_base = gpio_base;
if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
initial_state = mux->data.idle;
muxc->deselect = i2c_mux_gpio_deselect;
} else {
initial_state = mux->data.values[0];
}
for (i = 0; i < mux->data.n_gpios; i++) {
struct device *gpio_dev;
struct gpio_desc *gpio_desc;
ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
if (ret) {
dev_err(&pdev->dev, "Failed to request GPIO %d\n",
mux->data.gpios[i]);
goto err_request_gpio;
}
ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
initial_state & (1 << i));
if (ret) {
dev_err(&pdev->dev,
"Failed to set direction of GPIO %d to output\n",
mux->data.gpios[i]);
i++; /* gpio_request above succeeded, so must free */
goto err_request_gpio;
}
gpio_desc = gpio_to_desc(gpio_base + mux->data.gpios[i]);
mux->gpios[i] = gpio_desc;
if (!muxc->mux_locked)
continue;
gpio_dev = &gpio_desc->gdev->dev;
muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
}
if (muxc->mux_locked)
dev_info(&pdev->dev, "mux-locked i2c mux\n");
for (i = 0; i < mux->data.n_values; i++) {
u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
if (ret)
goto add_adapter_failed;
}
dev_info(&pdev->dev, "%d port mux on %s adapter\n",
mux->data.n_values, parent->name);
return 0;
add_adapter_failed:
i2c_mux_del_adapters(muxc);
i = mux->data.n_gpios;
err_request_gpio:
for (; i > 0; i--)
gpio_free(gpio_base + mux->data.gpios[i - 1]);
alloc_failed:
i2c_put_adapter(parent);
return ret;
}
static int i2c_mux_gpio_remove(struct platform_device *pdev)
{
struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
struct gpiomux *mux = i2c_mux_priv(muxc);
int i;
i2c_mux_del_adapters(muxc);
for (i = 0; i < mux->data.n_gpios; i++)
gpio_free(mux->gpio_base + mux->data.gpios[i]);
i2c_put_adapter(muxc->parent);
return 0;
}
static const struct of_device_id i2c_mux_gpio_of_match[] = {
{ .compatible = "i2c-mux-gpio", },
{},
};
MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
static struct platform_driver i2c_mux_gpio_driver = {
.probe = i2c_mux_gpio_probe,
.remove = i2c_mux_gpio_remove,
.driver = {
.name = "i2c-mux-gpio",
.of_match_table = i2c_mux_gpio_of_match,
},
};
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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