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
  25 struct led_pwm_data {
  26         struct led_classdev     cdev;
  27         struct pwm_device       *pwm;
  28         unsigned int            active_low;
  29         unsigned int            period;
  30         unsigned int            max_brightness;
  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->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                         dev_err(&pdev->dev, "unable to request PWM %d\n",
  73                                         cur_led->pwm_id);
  74                         goto err;
  75                 }
  76
  77                 led_dat->cdev.name = cur_led->name;
  78                 led_dat->cdev.default_trigger = cur_led->default_trigger;
  79                 led_dat->active_low = cur_led->active_low;
  80                 led_dat->max_brightness = cur_led->max_brightness;
  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.flags |= LED_CORE_SUSPENDRESUME;
  85
  86                 ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
  87                 if (ret < 0) {
  88                         pwm_free(led_dat->pwm);
  89                         goto err;
  90                 }
  91         }
  92
  93         platform_set_drvdata(pdev, leds_data);
  94
  95         return 0;
  96
  97 err:
  98         if (i > 0) {
  99                 for (i = i - 1; i >= 0; i--) {
 100                         led_classdev_unregister(&leds_data[i].cdev);
 101                         pwm_free(leds_data[i].pwm);
 102                 }
 103         }
 104
 105         kfree(leds_data);
 106
 107         return ret;
 108 }
 109
 110 static int __devexit 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         kfree(leds_data);
 124
 125         return 0;
 126 }
 127
 128 static struct platform_driver led_pwm_driver = {
 129         .probe          = led_pwm_probe,
 130         .remove         = __devexit_p(led_pwm_remove),
 131         .driver         = {
 132                 .name   = "leds_pwm",
 133                 .owner  = THIS_MODULE,
 134         },
 135 };
 136
 137 static int __init led_pwm_init(void)
 138 {
 139         return platform_driver_register(&led_pwm_driver);
 140 }
 141
 142 static void __exit led_pwm_exit(void)
 143 {
 144         platform_driver_unregister(&led_pwm_driver);
 145 }
 146
 147 module_init(led_pwm_init);
 148 module_exit(led_pwm_exit);
 149
 150 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 151 MODULE_DESCRIPTION("PWM LED driver for PXA");
 152 MODULE_LICENSE("GPL");
 153 MODULE_ALIAS("platform:leds-pwm");