drivers/leds/leds-regulator.c

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