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// SPDX-License-Identifier: GPL-2.0-only
/*
* I2C multiplexer using GPIO API
*
* Peter Korsgaard <peter.korsgaard@barco.com>
*/
#include <linux/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/platform_data/i2c-mux-gpio.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/bits.h>
#include <linux/gpio/consumer.h>
/* FIXME: stop poking around inside gpiolib */
#include "../../gpio/gpiolib.h"
struct gpiomux {
struct i2c_mux_gpio_platform_data data;
int ngpios;
struct gpio_desc **gpios;
};
static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
{
DECLARE_BITMAP(values, BITS_PER_TYPE(val));
values[0] = val;
gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, 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;
}
#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;
int i = 0;
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;
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;
int i, ngpios, 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));
}
ngpios = gpiod_count(&pdev->dev, "mux");
if (ngpios <= 0) {
dev_err(&pdev->dev, "no valid gpios provided\n");
return ngpios ?: -EINVAL;
}
mux->ngpios = ngpios;
parent = i2c_get_adapter(mux->data.parent);
if (!parent)
return -EPROBE_DEFER;
muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
ngpios * sizeof(*mux->gpios), 0,
i2c_mux_gpio_select, NULL);
if (!muxc) {
ret = -ENOMEM;
goto alloc_failed;
}
mux->gpios = muxc->priv;
muxc->priv = mux;
platform_set_drvdata(pdev, muxc);
root = i2c_root_adapter(&parent->dev);
muxc->mux_locked = true;
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 < ngpios; i++) {
struct device *gpio_dev;
struct gpio_desc *gpiod;
enum gpiod_flags flag;
if (initial_state & BIT(i))
flag = GPIOD_OUT_HIGH;
else
flag = GPIOD_OUT_LOW;
gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
if (IS_ERR(gpiod)) {
ret = PTR_ERR(gpiod);
goto alloc_failed;
}
mux->gpios[i] = gpiod;
if (!muxc->mux_locked)
continue;
/* FIXME: find a proper way to access the GPIO device */
gpio_dev = &gpiod->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);
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);
i2c_mux_del_adapters(muxc);
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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