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/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
  26 struct led_pwm_data {
  27         struct led_classdev     cdev;
  28         struct pwm_device       *pwm;
  29         unsigned int            active_low;
  30         unsigned int            period;
  31 };
  32
  33 static void led_pwm_set(struct led_classdev *led_cdev,
  34         enum led_brightness brightness)
  35 {
  36         struct led_pwm_data *led_dat =
  37                 container_of(led_cdev, struct led_pwm_data, cdev);
  38         unsigned int max = led_dat->cdev.max_brightness;
  39         unsigned int period =  led_dat->period;
  40
  41         if (brightness == 0) {
  42                 pwm_config(led_dat->pwm, 0, period);
  43                 pwm_disable(led_dat->pwm);
  44         } else {
  45                 pwm_config(led_dat->pwm, brightness * period / max, period);
  46                 pwm_enable(led_dat->pwm);
  47         }
  48 }
  49
  50 static int led_pwm_probe(struct platform_device *pdev)
  51 {
  52         struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
  53         struct led_pwm *cur_led;
  54         struct led_pwm_data *leds_data, *led_dat;
  55         int i, ret = 0;
  56
  57         if (!pdata)
  58                 return -EBUSY;
  59
  60         leds_data = devm_kzalloc(&pdev->dev,
  61                         sizeof(struct led_pwm_data) * pdata->num_leds,
  62                                 GFP_KERNEL);
  63         if (!leds_data)
  64                 return -ENOMEM;
  65
  66         for (i = 0; i < pdata->num_leds; i++) {
  67                 cur_led = &pdata->leds[i];
  68                 led_dat = &leds_data[i];
  69
  70                 led_dat->pwm = pwm_request(cur_led->pwm_id,
  71                                 cur_led->name);
  72                 if (IS_ERR(led_dat->pwm)) {
  73                         ret = PTR_ERR(led_dat->pwm);
  74                         dev_err(&pdev->dev, "unable to request PWM %d\n",
  75                                         cur_led->pwm_id);
  76                         goto err;
  77                 }
  78
  79                 led_dat->cdev.name = cur_led->name;
  80                 led_dat->cdev.default_trigger = cur_led->default_trigger;
  81                 led_dat->active_low = cur_led->active_low;
  82                 led_dat->period = cur_led->pwm_period_ns;
  83                 led_dat->cdev.brightness_set = led_pwm_set;
  84                 led_dat->cdev.brightness = LED_OFF;
  85                 led_dat->cdev.max_brightness = cur_led->max_brightness;
  86                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
  87
  88                 ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
  89                 if (ret < 0) {
  90                         pwm_free(led_dat->pwm);
  91                         goto err;
  92                 }
  93         }
  94
  95         platform_set_drvdata(pdev, leds_data);
  96
  97         return 0;
  98
  99 err:
 100         if (i > 0) {
 101                 for (i = i - 1; i >= 0; i--) {
 102                         led_classdev_unregister(&leds_data[i].cdev);
 103                         pwm_free(leds_data[i].pwm);
 104                 }
 105         }
 106
 107         return ret;
 108 }
 109
 110 static int led_pwm_remove(struct platform_device *pdev)
 111 {
 112         int i;
 113         struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
 114         struct led_pwm_data *leds_data;
 115
 116         leds_data = platform_get_drvdata(pdev);
 117
 118         for (i = 0; i < pdata->num_leds; i++) {
 119                 led_classdev_unregister(&leds_data[i].cdev);
 120                 pwm_free(leds_data[i].pwm);
 121         }
 122
 123         return 0;
 124 }
 125
 126 static struct platform_driver led_pwm_driver = {
 127         .probe          = led_pwm_probe,
 128         .remove         = led_pwm_remove,
 129         .driver         = {
 130                 .name   = "leds_pwm",
 131                 .owner  = THIS_MODULE,
 132         },
 133 };
 134
 135 module_platform_driver(led_pwm_driver);
 136
 137 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 138 MODULE_DESCRIPTION("PWM LED driver for PXA");
 139 MODULE_LICENSE("GPL");
 140 MODULE_ALIAS("platform:leds-pwm");