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