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  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * GPIO-controlled multiplexer driver
  4 *
  5 * Copyright (C) 2017 Axentia Technologies AB
  6 *
  7 * Author: Peter Rosin <peda@axentia.se>
  8 */
  9
 10#include <linux/err.h>
 11#include <linux/gpio/consumer.h>
 12#include <linux/module.h>
 13#include <linux/mux/driver.h>
 14#include <linux/of_platform.h>
 15#include <linux/platform_device.h>
 16#include <linux/property.h>
 17
 18struct mux_gpio {
 19	struct gpio_descs *gpios;
 20};
 21
 22static int mux_gpio_set(struct mux_control *mux, int state)
 23{
 24	struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
 25	DECLARE_BITMAP(values, BITS_PER_TYPE(state));
 26
 27	values[0] = state;
 28
 29	gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs,
 30				       mux_gpio->gpios->desc,
 31				       mux_gpio->gpios->info, values);
 32
 33	return 0;
 34}
 35
 36static const struct mux_control_ops mux_gpio_ops = {
 37	.set = mux_gpio_set,
 38};
 39
 40static const struct of_device_id mux_gpio_dt_ids[] = {
 41	{ .compatible = "gpio-mux", },
 42	{ /* sentinel */ }
 43};
 44MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
 45
 46static int mux_gpio_probe(struct platform_device *pdev)
 47{
 48	struct device *dev = &pdev->dev;
 49	struct mux_chip *mux_chip;
 50	struct mux_gpio *mux_gpio;
 51	int pins;
 52	s32 idle_state;
 53	int ret;
 54
 55	pins = gpiod_count(dev, "mux");
 56	if (pins < 0)
 57		return pins;
 58
 59	mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio));
 60	if (IS_ERR(mux_chip))
 61		return PTR_ERR(mux_chip);
 62
 63	mux_gpio = mux_chip_priv(mux_chip);
 64	mux_chip->ops = &mux_gpio_ops;
 65
 66	mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
 67	if (IS_ERR(mux_gpio->gpios)) {
 68		ret = PTR_ERR(mux_gpio->gpios);
 69		if (ret != -EPROBE_DEFER)
 70			dev_err(dev, "failed to get gpios\n");
 71		return ret;
 72	}
 73	WARN_ON(pins != mux_gpio->gpios->ndescs);
 74	mux_chip->mux->states = 1 << pins;
 75
 76	ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
 77	if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
 78		if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
 79			dev_err(dev, "invalid idle-state %u\n", idle_state);
 80			return -EINVAL;
 81		}
 82
 83		mux_chip->mux->idle_state = idle_state;
 84	}
 85
 86	ret = devm_mux_chip_register(dev, mux_chip);
 87	if (ret < 0)
 88		return ret;
 89
 90	dev_info(dev, "%u-way mux-controller registered\n",
 91		 mux_chip->mux->states);
 92
 93	return 0;
 94}
 95
 96static struct platform_driver mux_gpio_driver = {
 97	.driver = {
 98		.name = "gpio-mux",
 99		.of_match_table	= of_match_ptr(mux_gpio_dt_ids),
100	},
101	.probe = mux_gpio_probe,
102};
103module_platform_driver(mux_gpio_driver);
104
105MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
106MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
107MODULE_LICENSE("GPL v2");