LXR linux/drivers/mux/mux-gpio.c

   1/*
   2 * GPIO-controlled multiplexer driver
   3 *
   4 * Copyright (C) 2017 Axentia Technologies AB
   5 *
   6 * Author: Peter Rosin <peda@axentia.se>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 */
  12
  13#include <linux/err.h>
  14#include <linux/gpio/consumer.h>
  15#include <linux/module.h>
  16#include <linux/mux/driver.h>
  17#include <linux/of_platform.h>
  18#include <linux/platform_device.h>
  19#include <linux/property.h>
  20
  21struct mux_gpio {
  22        struct gpio_descs *gpios;
  23        int *val;
  24};
  25
  26static int mux_gpio_set(struct mux_control *mux, int state)
  27{
  28        struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
  29        int i;
  30
  31        for (i = 0; i < mux_gpio->gpios->ndescs; i++)
  32                mux_gpio->val[i] = (state >> i) & 1;
  33
  34        gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs,
  35                                       mux_gpio->gpios->desc,
  36                                       mux_gpio->val);
  37
  38        return 0;
  39}
  40
  41static const struct mux_control_ops mux_gpio_ops = {
  42        .set = mux_gpio_set,
  43};
  44
  45static const struct of_device_id mux_gpio_dt_ids[] = {
  46        { .compatible = "gpio-mux", },
  47        { /* sentinel */ }
  48};
  49MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
  50
  51static int mux_gpio_probe(struct platform_device *pdev)
  52{
  53        struct device *dev = &pdev->dev;
  54        struct mux_chip *mux_chip;
  55        struct mux_gpio *mux_gpio;
  56        int pins;
  57        s32 idle_state;
  58        int ret;
  59
  60        pins = gpiod_count(dev, "mux");
  61        if (pins < 0)
  62                return pins;
  63
  64        mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio) +
  65                                       pins * sizeof(*mux_gpio->val));
  66        if (IS_ERR(mux_chip))
  67                return PTR_ERR(mux_chip);
  68
  69        mux_gpio = mux_chip_priv(mux_chip);
  70        mux_gpio->val = (int *)(mux_gpio + 1);
  71        mux_chip->ops = &mux_gpio_ops;
  72
  73        mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
  74        if (IS_ERR(mux_gpio->gpios)) {
  75                ret = PTR_ERR(mux_gpio->gpios);
  76                if (ret != -EPROBE_DEFER)
  77                        dev_err(dev, "failed to get gpios\n");
  78                return ret;
  79        }
  80        WARN_ON(pins != mux_gpio->gpios->ndescs);
  81        mux_chip->mux->states = 1 << pins;
  82
  83        ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
  84        if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
  85                if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
  86                        dev_err(dev, "invalid idle-state %u\n", idle_state);
  87                        return -EINVAL;
  88                }
  89
  90                mux_chip->mux->idle_state = idle_state;
  91        }
  92
  93        ret = devm_mux_chip_register(dev, mux_chip);
  94        if (ret < 0)
  95                return ret;
  96
  97        dev_info(dev, "%u-way mux-controller registered\n",
  98                 mux_chip->mux->states);
  99
 100        return 0;
 101}
 102
 103static struct platform_driver mux_gpio_driver = {
 104        .driver = {
 105                .name = "gpio-mux",
 106                .of_match_table = of_match_ptr(mux_gpio_dt_ids),
 107        },
 108        .probe = mux_gpio_probe,
 109};
 110module_platform_driver(mux_gpio_driver);
 111
 112MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
 113MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
 114MODULE_LICENSE("GPL v2");
 115