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/*
* GPIO-controlled multiplexer driver
*
* Copyright (C) 2017 Axentia Technologies AB
*
* Author: Peter Rosin <peda@axentia.se>
*
* 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/err.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/mux/driver.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/property.h>
struct mux_gpio {
struct gpio_descs *gpios;
int *val;
};
static int mux_gpio_set(struct mux_control *mux, int state)
{
struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
int i;
for (i = 0; i < mux_gpio->gpios->ndescs; i++)
mux_gpio->val[i] = (state >> i) & 1;
gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs,
mux_gpio->gpios->desc,
mux_gpio->val);
return 0;
}
static const struct mux_control_ops mux_gpio_ops = {
.set = mux_gpio_set,
};
static const struct of_device_id mux_gpio_dt_ids[] = {
{ .compatible = "gpio-mux", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
static int mux_gpio_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct mux_chip *mux_chip;
struct mux_gpio *mux_gpio;
int pins;
s32 idle_state;
int ret;
pins = gpiod_count(dev, "mux");
if (pins < 0)
return pins;
mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio) +
pins * sizeof(*mux_gpio->val));
if (IS_ERR(mux_chip))
return PTR_ERR(mux_chip);
mux_gpio = mux_chip_priv(mux_chip);
mux_gpio->val = (int *)(mux_gpio + 1);
mux_chip->ops = &mux_gpio_ops;
mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
if (IS_ERR(mux_gpio->gpios)) {
ret = PTR_ERR(mux_gpio->gpios);
if (ret != -EPROBE_DEFER)
dev_err(dev, "failed to get gpios\n");
return ret;
}
WARN_ON(pins != mux_gpio->gpios->ndescs);
mux_chip->mux->states = 1 << pins;
ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
dev_err(dev, "invalid idle-state %u\n", idle_state);
return -EINVAL;
}
mux_chip->mux->idle_state = idle_state;
}
ret = devm_mux_chip_register(dev, mux_chip);
if (ret < 0)
return ret;
dev_info(dev, "%u-way mux-controller registered\n",
mux_chip->mux->states);
return 0;
}
static struct platform_driver mux_gpio_driver = {
.driver = {
.name = "gpio-mux",
.of_match_table = of_match_ptr(mux_gpio_dt_ids),
},
.probe = mux_gpio_probe,
};
module_platform_driver(mux_gpio_driver);
MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
MODULE_LICENSE("GPL v2");
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