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
  18 struct mux_gpio {
  19         struct gpio_descs *gpios;
  20 };
  21
  22 static 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
  36 static const struct mux_control_ops mux_gpio_ops = {
  37         .set = mux_gpio_set,
  38 };
  39
  40 static const struct of_device_id mux_gpio_dt_ids[] = {
  41         { .compatible = "gpio-mux", },
  42         { /* sentinel */ }
  43 };
  44 MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
  45
  46 static 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
  96 static 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 };
 103 module_platform_driver(mux_gpio_driver);
 104
 105 MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
 106 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
 107 MODULE_LICENSE("GPL v2");