gpio.c

  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/bitmap.h>
 11#include <linux/err.h>
 12#include <linux/gpio/consumer.h>
 13#include <linux/mod_devicetable.h>
 14#include <linux/module.h>
 15#include <linux/mux/driver.h>
 16#include <linux/platform_device.h>
 17#include <linux/property.h>
 18#include <linux/regulator/consumer.h>
 19
 20struct mux_gpio {
 21	struct gpio_descs *gpios;
 22};
 23
 24static int mux_gpio_set(struct mux_control *mux, int state)
 25{
 26	struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
 27	DECLARE_BITMAP(values, BITS_PER_TYPE(state));
 28	u32 value = state;
 29
 30	bitmap_from_arr32(values, &value, BITS_PER_TYPE(value));
 31
 32	gpiod_multi_set_value_cansleep(mux_gpio->gpios, values);
 33
 34	return 0;
 35}
 36
 37static const struct mux_control_ops mux_gpio_ops = {
 38	.set = mux_gpio_set,
 39};
 40
 41static const struct of_device_id mux_gpio_dt_ids[] = {
 42	{ .compatible = "gpio-mux", },
 43	{ /* sentinel */ }
 44};
 45MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
 46
 47static int mux_gpio_probe(struct platform_device *pdev)
 48{
 49	struct device *dev = &pdev->dev;
 50	struct mux_chip *mux_chip;
 51	struct mux_gpio *mux_gpio;
 52	int pins;
 53	s32 idle_state;
 54	int ret;
 55
 56	pins = gpiod_count(dev, "mux");
 57	if (pins < 0)
 58		return pins;
 59
 60	mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio));
 61	if (IS_ERR(mux_chip))
 62		return PTR_ERR(mux_chip);
 63
 64	mux_gpio = mux_chip_priv(mux_chip);
 65	mux_chip->ops = &mux_gpio_ops;
 66
 67	mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
 68	if (IS_ERR(mux_gpio->gpios))
 69		return dev_err_probe(dev, PTR_ERR(mux_gpio->gpios),
 70				     "failed to get gpios\n");
 71	WARN_ON(pins != mux_gpio->gpios->ndescs);
 72	mux_chip->mux->states = BIT(pins);
 73
 74	ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
 75	if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
 76		if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
 77			dev_err(dev, "invalid idle-state %u\n", idle_state);
 78			return -EINVAL;
 79		}
 80
 81		mux_chip->mux->idle_state = idle_state;
 82	}
 83
 84	ret = devm_regulator_get_enable_optional(dev, "mux");
 85	if (ret && ret != -ENODEV)
 86		return dev_err_probe(dev, ret, "failed to get/enable mux supply\n");
 87
 88	ret = devm_mux_chip_register(dev, mux_chip);
 89	if (ret < 0)
 90		return ret;
 91
 92	dev_info(dev, "%u-way mux-controller registered\n",
 93		 mux_chip->mux->states);
 94
 95	return 0;
 96}
 97
 98static struct platform_driver mux_gpio_driver = {
 99	.driver = {
100		.name = "gpio-mux",
101		.of_match_table	= mux_gpio_dt_ids,
102	},
103	.probe = mux_gpio_probe,
104};
105module_platform_driver(mux_gpio_driver);
106
107MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
108MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
109MODULE_LICENSE("GPL v2");