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/platform_device.h>
  18 #include <linux/of_platform.h>
  19 #include <linux/fb.h>
  20 #include <linux/leds.h>
  21 #include <linux/err.h>
  22 #include <linux/pwm.h>
  23 #include <linux/leds_pwm.h>
  24 #include <linux/slab.h>
  25 #include <linux/workqueue.h>
  26
  27 struct led_pwm_data {
  28         struct led_classdev     cdev;
  29         struct pwm_device       *pwm;
  30         struct work_struct      work;
  31         unsigned int            active_low;
  32         unsigned int            period;
  33         int                     duty;
  34         bool                    can_sleep;
  35 };
  36
  37 struct led_pwm_priv {
  38         int num_leds;
  39         struct led_pwm_data leds[0];
  40 };
  41
  42 static void __led_pwm_set(struct led_pwm_data *led_dat)
  43 {
  44         int new_duty = led_dat->duty;
  45
  46         pwm_config(led_dat->pwm, new_duty, led_dat->period);
  47
  48         if (new_duty == 0)
  49                 pwm_disable(led_dat->pwm);
  50         else
  51                 pwm_enable(led_dat->pwm);
  52 }
  53
  54 static void led_pwm_work(struct work_struct *work)
  55 {
  56         struct led_pwm_data *led_dat =
  57                 container_of(work, struct led_pwm_data, work);
  58
  59         __led_pwm_set(led_dat);
  60 }
  61
  62 static void led_pwm_set(struct led_classdev *led_cdev,
  63         enum led_brightness brightness)
  64 {
  65         struct led_pwm_data *led_dat =
  66                 container_of(led_cdev, struct led_pwm_data, cdev);
  67         unsigned int max = led_dat->cdev.max_brightness;
  68         unsigned long long duty =  led_dat->period;
  69
  70         duty *= brightness;
  71         do_div(duty, max);
  72         led_dat->duty = duty;
  73
  74         if (led_dat->can_sleep)
  75                 schedule_work(&led_dat->work);
  76         else
  77                 __led_pwm_set(led_dat);
  78 }
  79
  80 static inline size_t sizeof_pwm_leds_priv(int num_leds)
  81 {
  82         return sizeof(struct led_pwm_priv) +
  83                       (sizeof(struct led_pwm_data) * num_leds);
  84 }
  85
  86 static void led_pwm_cleanup(struct led_pwm_priv *priv)
  87 {
  88         while (priv->num_leds--) {
  89                 led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
  90                 if (priv->leds[priv->num_leds].can_sleep)
  91                         cancel_work_sync(&priv->leds[priv->num_leds].work);
  92         }
  93 }
  94
  95 static int led_pwm_create_of(struct platform_device *pdev,
  96                              struct led_pwm_priv *priv)
  97 {
  98         struct device_node *child;
  99         int ret;
 100
 101         for_each_child_of_node(pdev->dev.of_node, child) {
 102                 struct led_pwm_data *led_dat = &priv->leds[priv->num_leds];
 103
 104                 led_dat->cdev.name = of_get_property(child, "label",
 105                                                      NULL) ? : child->name;
 106
 107                 led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL);
 108                 if (IS_ERR(led_dat->pwm)) {
 109                         dev_err(&pdev->dev, "unable to request PWM for %s\n",
 110                                 led_dat->cdev.name);
 111                         ret = PTR_ERR(led_dat->pwm);
 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 0;
 141 err:
 142         led_pwm_cleanup(priv);
 143
 144         return ret;
 145 }
 146
 147 static int led_pwm_probe(struct platform_device *pdev)
 148 {
 149         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
 150         struct led_pwm_priv *priv;
 151         int count, i;
 152         int ret = 0;
 153
 154         if (pdata)
 155                 count = pdata->num_leds;
 156         else
 157                 count = of_get_child_count(pdev->dev.of_node);
 158
 159         if (!count)
 160                 return -EINVAL;
 161
 162         priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
 163                             GFP_KERNEL);
 164         if (!priv)
 165                 return -ENOMEM;
 166
 167         if (pdata) {
 168                 for (i = 0; i < count; i++) {
 169                         struct led_pwm *cur_led = &pdata->leds[i];
 170                         struct led_pwm_data *led_dat = &priv->leds[i];
 171
 172                         led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name);
 173                         if (IS_ERR(led_dat->pwm)) {
 174                                 ret = PTR_ERR(led_dat->pwm);
 175                                 dev_err(&pdev->dev,
 176                                         "unable to request PWM for %s\n",
 177                                         cur_led->name);
 178                                 goto err;
 179                         }
 180
 181                         led_dat->cdev.name = cur_led->name;
 182                         led_dat->cdev.default_trigger = cur_led->default_trigger;
 183                         led_dat->active_low = cur_led->active_low;
 184                         led_dat->period = cur_led->pwm_period_ns;
 185                         led_dat->cdev.brightness_set = led_pwm_set;
 186                         led_dat->cdev.brightness = LED_OFF;
 187                         led_dat->cdev.max_brightness = cur_led->max_brightness;
 188                         led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 189
 190                         led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
 191                         if (led_dat->can_sleep)
 192                                 INIT_WORK(&led_dat->work, led_pwm_work);
 193
 194                         ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
 195                         if (ret < 0)
 196                                 goto err;
 197                 }
 198                 priv->num_leds = count;
 199         } else {
 200                 ret = led_pwm_create_of(pdev, priv);
 201                 if (ret)
 202                         return ret;
 203         }
 204
 205         platform_set_drvdata(pdev, priv);
 206
 207         return 0;
 208
 209 err:
 210         priv->num_leds = i;
 211         led_pwm_cleanup(priv);
 212
 213         return ret;
 214 }
 215
 216 static int led_pwm_remove(struct platform_device *pdev)
 217 {
 218         struct led_pwm_priv *priv = platform_get_drvdata(pdev);
 219
 220         led_pwm_cleanup(priv);
 221
 222         return 0;
 223 }
 224
 225 static const struct of_device_id of_pwm_leds_match[] = {
 226         { .compatible = "pwm-leds", },
 227         {},
 228 };
 229 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 230
 231 static struct platform_driver led_pwm_driver = {
 232         .probe          = led_pwm_probe,
 233         .remove         = led_pwm_remove,
 234         .driver         = {
 235                 .name   = "leds_pwm",
 236                 .owner  = THIS_MODULE,
 237                 .of_match_table = of_pwm_leds_match,
 238         },
 239 };
 240
 241 module_platform_driver(led_pwm_driver);
 242
 243 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 244 MODULE_DESCRIPTION("PWM LED driver for PXA");
 245 MODULE_LICENSE("GPL");
 246 MODULE_ALIAS("platform:leds-pwm");