drivers/leds/leds-regulator.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * leds-regulator.c - LED class driver for regulator driven LEDs.
   4  *
   5  * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
   6  *
   7  * Inspired by leds-wm8350 driver.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/err.h>
  12 #include <linux/slab.h>
  13 #include <linux/leds.h>
  14 #include <linux/leds-regulator.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/regulator/consumer.h>
  17
  18 #define to_regulator_led(led_cdev) \
  19         container_of(led_cdev, struct regulator_led, cdev)
  20
  21 struct regulator_led {
  22         struct led_classdev cdev;
  23         int enabled;
  24         struct mutex mutex;
  25
  26         struct regulator *vcc;
  27 };
  28
  29 static inline int led_regulator_get_max_brightness(struct regulator *supply)
  30 {
  31         int ret;
  32         int voltage = regulator_list_voltage(supply, 0);
  33
  34         if (voltage <= 0)
  35                 return 1;
  36
  37         /* even if regulator can't change voltages,
  38          * we still assume it can change status
  39          * and the LED can be turned on and off.
  40          */
  41         ret = regulator_set_voltage(supply, voltage, voltage);
  42         if (ret < 0)
  43                 return 1;
  44
  45         return regulator_count_voltages(supply);
  46 }
  47
  48 static int led_regulator_get_voltage(struct regulator *supply,
  49                 enum led_brightness brightness)
  50 {
  51         if (brightness == 0)
  52                 return -EINVAL;
  53
  54         return regulator_list_voltage(supply, brightness - 1);
  55 }
  56
  57
  58 static void regulator_led_enable(struct regulator_led *led)
  59 {
  60         int ret;
  61
  62         if (led->enabled)
  63                 return;
  64
  65         ret = regulator_enable(led->vcc);
  66         if (ret != 0) {
  67                 dev_err(led->cdev.dev, "Failed to enable vcc: %d\n", ret);
  68                 return;
  69         }
  70
  71         led->enabled = 1;
  72 }
  73
  74 static void regulator_led_disable(struct regulator_led *led)
  75 {
  76         int ret;
  77
  78         if (!led->enabled)
  79                 return;
  80
  81         ret = regulator_disable(led->vcc);
  82         if (ret != 0) {
  83                 dev_err(led->cdev.dev, "Failed to disable vcc: %d\n", ret);
  84                 return;
  85         }
  86
  87         led->enabled = 0;
  88 }
  89
  90 static int regulator_led_brightness_set(struct led_classdev *led_cdev,
  91                                          enum led_brightness value)
  92 {
  93         struct regulator_led *led = to_regulator_led(led_cdev);
  94         int voltage;
  95         int ret = 0;
  96
  97         mutex_lock(&led->mutex);
  98
  99         if (value == LED_OFF) {
 100                 regulator_led_disable(led);
 101                 goto out;
 102         }
 103
 104         if (led->cdev.max_brightness > 1) {
 105                 voltage = led_regulator_get_voltage(led->vcc, value);
 106                 dev_dbg(led->cdev.dev, "brightness: %d voltage: %d\n",
 107                                 value, voltage);
 108
 109                 ret = regulator_set_voltage(led->vcc, voltage, voltage);
 110                 if (ret != 0)
 111                         dev_err(led->cdev.dev, "Failed to set voltage %d: %d\n",
 112                                 voltage, ret);
 113         }
 114
 115         regulator_led_enable(led);
 116
 117 out:
 118         mutex_unlock(&led->mutex);
 119         return ret;
 120 }
 121
 122 static int regulator_led_probe(struct platform_device *pdev)
 123 {
 124         struct led_regulator_platform_data *pdata =
 125                         dev_get_platdata(&pdev->dev);
 126         struct regulator_led *led;
 127         struct regulator *vcc;
 128         int ret = 0;
 129
 130         if (pdata == NULL) {
 131                 dev_err(&pdev->dev, "no platform data\n");
 132                 return -ENODEV;
 133         }
 134
 135         vcc = devm_regulator_get_exclusive(&pdev->dev, "vled");
 136         if (IS_ERR(vcc)) {
 137                 dev_err(&pdev->dev, "Cannot get vcc for %s\n", pdata->name);
 138                 return PTR_ERR(vcc);
 139         }
 140
 141         led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
 142         if (led == NULL)
 143                 return -ENOMEM;
 144
 145         led->cdev.max_brightness = led_regulator_get_max_brightness(vcc);
 146         if (pdata->brightness > led->cdev.max_brightness) {
 147                 dev_err(&pdev->dev, "Invalid default brightness %d\n",
 148                                 pdata->brightness);
 149                 return -EINVAL;
 150         }
 151
 152         led->cdev.brightness_set_blocking = regulator_led_brightness_set;
 153         led->cdev.name = pdata->name;
 154         led->cdev.flags |= LED_CORE_SUSPENDRESUME;
 155         led->vcc = vcc;
 156
 157         /* to handle correctly an already enabled regulator */
 158         if (regulator_is_enabled(led->vcc))
 159                 led->enabled = 1;
 160
 161         mutex_init(&led->mutex);
 162
 163         platform_set_drvdata(pdev, led);
 164
 165         ret = led_classdev_register(&pdev->dev, &led->cdev);
 166         if (ret < 0)
 167                 return ret;
 168
 169         /* to expose the default value to userspace */
 170         led->cdev.brightness = pdata->brightness;
 171
 172         /* Set the default led status */
 173         regulator_led_brightness_set(&led->cdev, led->cdev.brightness);
 174
 175         return 0;
 176 }
 177
 178 static int regulator_led_remove(struct platform_device *pdev)
 179 {
 180         struct regulator_led *led = platform_get_drvdata(pdev);
 181
 182         led_classdev_unregister(&led->cdev);
 183         regulator_led_disable(led);
 184         return 0;
 185 }
 186
 187 static struct platform_driver regulator_led_driver = {
 188         .driver = {
 189                    .name  = "leds-regulator",
 190                    },
 191         .probe  = regulator_led_probe,
 192         .remove = regulator_led_remove,
 193 };
 194
 195 module_platform_driver(regulator_led_driver);
 196
 197 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
 198 MODULE_DESCRIPTION("Regulator driven LED driver");
 199 MODULE_LICENSE("GPL");
 200 MODULE_ALIAS("platform:leds-regulator");