drivers/leds/leds-pwm.c

   1 /*
   2  * linux/drivers/leds-pwm.c
   3  *
   4  * simple PWM based LED control
   5  *
   6  * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de)
   7  *
   8  * based on leds-gpio.c by Raphael Assenat <raph@8d.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/of_platform.h>
  20 #include <linux/fb.h>
  21 #include <linux/leds.h>
  22 #include <linux/err.h>
  23 #include <linux/pwm.h>
  24 #include <linux/leds_pwm.h>
  25 #include <linux/slab.h>
  26 #include <linux/workqueue.h>
  27
  28 struct led_pwm_data {
  29         struct led_classdev     cdev;
  30         struct pwm_device       *pwm;
  31         struct work_struct      work;
  32         unsigned int            active_low;
  33         unsigned int            period;
  34         int                     duty;
  35         bool                    can_sleep;
  36 };
  37
  38 struct led_pwm_priv {
  39         int num_leds;
  40         struct led_pwm_data leds[0];
  41 };
  42
  43 static void __led_pwm_set(struct led_pwm_data *led_dat)
  44 {
  45         int new_duty = led_dat->duty;
  46
  47         pwm_config(led_dat->pwm, new_duty, led_dat->period);
  48
  49         if (new_duty == 0)
  50                 pwm_disable(led_dat->pwm);
  51         else
  52                 pwm_enable(led_dat->pwm);
  53 }
  54
  55 static void led_pwm_work(struct work_struct *work)
  56 {
  57         struct led_pwm_data *led_dat =
  58                 container_of(work, struct led_pwm_data, work);
  59
  60         __led_pwm_set(led_dat);
  61 }
  62
  63 static void led_pwm_set(struct led_classdev *led_cdev,
  64         enum led_brightness brightness)
  65 {
  66         struct led_pwm_data *led_dat =
  67                 container_of(led_cdev, struct led_pwm_data, cdev);
  68         unsigned int max = led_dat->cdev.max_brightness;
  69         unsigned int period =  led_dat->period;
  70
  71         led_dat->duty = brightness * period / max;
  72
  73         if (led_dat->can_sleep)
  74                 schedule_work(&led_dat->work);
  75         else
  76                 __led_pwm_set(led_dat);
  77 }
  78
  79 static inline size_t sizeof_pwm_leds_priv(int num_leds)
  80 {
  81         return sizeof(struct led_pwm_priv) +
  82                       (sizeof(struct led_pwm_data) * num_leds);
  83 }
  84
  85 static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev)
  86 {
  87         struct device_node *node = pdev->dev.of_node;
  88         struct device_node *child;
  89         struct led_pwm_priv *priv;
  90         int count, ret;
  91
  92         /* count LEDs in this device, so we know how much to allocate */
  93         count = of_get_child_count(node);
  94         if (!count)
  95                 return NULL;
  96
  97         priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
  98                             GFP_KERNEL);
  99         if (!priv)
 100                 return NULL;
 101
 102         for_each_child_of_node(node, child) {
 103                 struct led_pwm_data *led_dat = &priv->leds[priv->num_leds];
 104
 105                 led_dat->cdev.name = of_get_property(child, "label",
 106                                                      NULL) ? : child->name;
 107
 108                 led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL);
 109                 if (IS_ERR(led_dat->pwm)) {
 110                         dev_err(&pdev->dev, "unable to request PWM for %s\n",
 111                                 led_dat->cdev.name);
 112                         goto err;
 113                 }
 114                 /* Get the period from PWM core when n*/
 115                 led_dat->period = pwm_get_period(led_dat->pwm);
 116
 117                 led_dat->cdev.default_trigger = of_get_property(child,
 118                                                 "linux,default-trigger", NULL);
 119                 of_property_read_u32(child, "max-brightness",
 120                                      &led_dat->cdev.max_brightness);
 121
 122                 led_dat->cdev.brightness_set = led_pwm_set;
 123                 led_dat->cdev.brightness = LED_OFF;
 124                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 125
 126                 led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
 127                 if (led_dat->can_sleep)
 128                         INIT_WORK(&led_dat->work, led_pwm_work);
 129
 130                 ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
 131                 if (ret < 0) {
 132                         dev_err(&pdev->dev, "failed to register for %s\n",
 133                                 led_dat->cdev.name);
 134                         of_node_put(child);
 135                         goto err;
 136                 }
 137                 priv->num_leds++;
 138         }
 139
 140         return priv;
 141 err:
 142         while (priv->num_leds--)
 143                 led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
 144
 145         return NULL;
 146 }
 147
 148 static int led_pwm_probe(struct platform_device *pdev)
 149 {
 150         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
 151         struct led_pwm_priv *priv;
 152         int i, ret = 0;
 153
 154         if (pdata && pdata->num_leds) {
 155                 priv = devm_kzalloc(&pdev->dev,
 156                                     sizeof_pwm_leds_priv(pdata->num_leds),
 157                                     GFP_KERNEL);
 158                 if (!priv)
 159                         return -ENOMEM;
 160
 161                 for (i = 0; i < pdata->num_leds; i++) {
 162                         struct led_pwm *cur_led = &pdata->leds[i];
 163                         struct led_pwm_data *led_dat = &priv->leds[i];
 164
 165                         led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name);
 166                         if (IS_ERR(led_dat->pwm)) {
 167                                 ret = PTR_ERR(led_dat->pwm);
 168                                 dev_err(&pdev->dev,
 169                                         "unable to request PWM for %s\n",
 170                                         cur_led->name);
 171                                 goto err;
 172                         }
 173
 174                         led_dat->cdev.name = cur_led->name;
 175                         led_dat->cdev.default_trigger = cur_led->default_trigger;
 176                         led_dat->active_low = cur_led->active_low;
 177                         led_dat->period = cur_led->pwm_period_ns;
 178                         led_dat->cdev.brightness_set = led_pwm_set;
 179                         led_dat->cdev.brightness = LED_OFF;
 180                         led_dat->cdev.max_brightness = cur_led->max_brightness;
 181                         led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 182
 183                         led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
 184                         if (led_dat->can_sleep)
 185                                 INIT_WORK(&led_dat->work, led_pwm_work);
 186
 187                         ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
 188                         if (ret < 0)
 189                                 goto err;
 190                 }
 191                 priv->num_leds = pdata->num_leds;
 192         } else {
 193                 priv = led_pwm_create_of(pdev);
 194                 if (!priv)
 195                         return -ENODEV;
 196         }
 197
 198         platform_set_drvdata(pdev, priv);
 199
 200         return 0;
 201
 202 err:
 203         while (i--)
 204                 led_classdev_unregister(&priv->leds[i].cdev);
 205
 206         return ret;
 207 }
 208
 209 static int led_pwm_remove(struct platform_device *pdev)
 210 {
 211         struct led_pwm_priv *priv = platform_get_drvdata(pdev);
 212         int i;
 213
 214         for (i = 0; i < priv->num_leds; i++) {
 215                 led_classdev_unregister(&priv->leds[i].cdev);
 216                 if (priv->leds[i].can_sleep)
 217                         cancel_work_sync(&priv->leds[i].work);
 218         }
 219
 220         return 0;
 221 }
 222
 223 static const struct of_device_id of_pwm_leds_match[] = {
 224         { .compatible = "pwm-leds", },
 225         {},
 226 };
 227 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 228
 229 static struct platform_driver led_pwm_driver = {
 230         .probe          = led_pwm_probe,
 231         .remove         = led_pwm_remove,
 232         .driver         = {
 233                 .name   = "leds_pwm",
 234                 .owner  = THIS_MODULE,
 235                 .of_match_table = of_pwm_leds_match,
 236         },
 237 };
 238
 239 module_platform_driver(led_pwm_driver);
 240
 241 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 242 MODULE_DESCRIPTION("PWM LED driver for PXA");
 243 MODULE_LICENSE("GPL");
 244 MODULE_ALIAS("platform:leds-pwm");