LXR linux/drivers/mux/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/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");
 108