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 = kzalloc(sizeof(struct led_pwm_data) * pdata->num_leds,
  61                                 GFP_KERNEL);
  62         if (!leds_data)
  63                 return -ENOMEM;
  64
  65         for (i = 0; i < pdata->num_leds; i++) {
  66                 cur_led = &pdata->leds[i];
  67                 led_dat = &leds_data[i];
  68
  69                 led_dat->pwm = pwm_request(cur_led->pwm_id,
  70                                 cur_led->name);
  71                 if (IS_ERR(led_dat->pwm)) {
  72                         ret = PTR_ERR(led_dat->pwm);
  73                         dev_err(&pdev->dev, "unable to request PWM %d\n",
  74                                         cur_led->pwm_id);
  75                         goto err;
  76                 }
  77
  78                 led_dat->cdev.name = cur_led->name;
  79                 led_dat->cdev.default_trigger = cur_led->default_trigger;
  80                 led_dat->active_low = cur_led->active_low;
  81                 led_dat->period = cur_led->pwm_period_ns;
  82                 led_dat->cdev.brightness_set = led_pwm_set;
  83                 led_dat->cdev.brightness = LED_OFF;
  84                 led_dat->cdev.max_brightness = cur_led->max_brightness;
  85                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
  86
  87                 ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
  88                 if (ret < 0) {
  89                         pwm_free(led_dat->pwm);
  90                         goto err;
  91                 }
  92         }
  93
  94         platform_set_drvdata(pdev, leds_data);
  95
  96         return 0;
  97
  98 err:
  99         if (i > 0) {
 100                 for (i = i - 1; i >= 0; i--) {
 101                         led_classdev_unregister(&leds_data[i].cdev);
 102                         pwm_free(leds_data[i].pwm);
 103                 }
 104         }
 105
 106         kfree(leds_data);
 107
 108         return ret;
 109 }
 110
 111 static int __devexit led_pwm_remove(struct platform_device *pdev)
 112 {
 113         int i;
 114         struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
 115         struct led_pwm_data *leds_data;
 116
 117         leds_data = platform_get_drvdata(pdev);
 118
 119         for (i = 0; i < pdata->num_leds; i++) {
 120                 led_classdev_unregister(&leds_data[i].cdev);
 121                 pwm_free(leds_data[i].pwm);
 122         }
 123
 124         kfree(leds_data);
 125
 126         return 0;
 127 }
 128
 129 static struct platform_driver led_pwm_driver = {
 130         .probe          = led_pwm_probe,
 131         .remove         = __devexit_p(led_pwm_remove),
 132         .driver         = {
 133                 .name   = "leds_pwm",
 134                 .owner  = THIS_MODULE,
 135         },
 136 };
 137
 138 static int __init led_pwm_init(void)
 139 {
 140         return platform_driver_register(&led_pwm_driver);
 141 }
 142
 143 static void __exit led_pwm_exit(void)
 144 {
 145         platform_driver_unregister(&led_pwm_driver);
 146 }
 147
 148 module_init(led_pwm_init);
 149 module_exit(led_pwm_exit);
 150
 151 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 152 MODULE_DESCRIPTION("PWM LED driver for PXA");
 153 MODULE_LICENSE("GPL");
 154 MODULE_ALIAS("platform:leds-pwm");