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 };
  31
  32 static void led_pwm_set(struct led_classdev *led_cdev,
  33         enum led_brightness brightness)
  34 {
  35         struct led_pwm_data *led_dat =
  36                 container_of(led_cdev, struct led_pwm_data, cdev);
  37         unsigned int max = led_dat->cdev.max_brightness;
  38         unsigned int period =  led_dat->period;
  39
  40         if (brightness == 0) {
  41                 pwm_config(led_dat->pwm, 0, period);
  42                 pwm_disable(led_dat->pwm);
  43         } else {
  44                 pwm_config(led_dat->pwm, brightness * period / max, period);
  45                 pwm_enable(led_dat->pwm);
  46         }
  47 }
  48
  49 static int led_pwm_probe(struct platform_device *pdev)
  50 {
  51         struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
  52         struct led_pwm *cur_led;
  53         struct led_pwm_data *leds_data, *led_dat;
  54         int i, ret = 0;
  55
  56         if (!pdata)
  57                 return -EBUSY;
  58
  59         leds_data = kzalloc(sizeof(struct led_pwm_data) * pdata->num_leds,
  60                                 GFP_KERNEL);
  61         if (!leds_data)
  62                 return -ENOMEM;
  63
  64         for (i = 0; i < pdata->num_leds; i++) {
  65                 cur_led = &pdata->leds[i];
  66                 led_dat = &leds_data[i];
  67
  68                 led_dat->pwm = pwm_request(cur_led->pwm_id,
  69                                 cur_led->name);
  70                 if (IS_ERR(led_dat->pwm)) {
  71                         dev_err(&pdev->dev, "unable to request PWM %d\n",
  72                                         cur_led->pwm_id);
  73                         goto err;
  74                 }
  75
  76                 led_dat->cdev.name = cur_led->name;
  77                 led_dat->cdev.default_trigger = cur_led->default_trigger;
  78                 led_dat->active_low = cur_led->active_low;
  79                 led_dat->period = cur_led->pwm_period_ns;
  80                 led_dat->cdev.brightness_set = led_pwm_set;
  81                 led_dat->cdev.brightness = LED_OFF;
  82                 led_dat->cdev.max_brightness = cur_led->max_brightness;
  83                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
  84
  85                 ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
  86                 if (ret < 0) {
  87                         pwm_free(led_dat->pwm);
  88                         goto err;
  89                 }
  90         }
  91
  92         platform_set_drvdata(pdev, leds_data);
  93
  94         return 0;
  95
  96 err:
  97         if (i > 0) {
  98                 for (i = i - 1; i >= 0; i--) {
  99                         led_classdev_unregister(&leds_data[i].cdev);
 100                         pwm_free(leds_data[i].pwm);
 101                 }
 102         }
 103
 104         kfree(leds_data);
 105
 106         return ret;
 107 }
 108
 109 static int __devexit led_pwm_remove(struct platform_device *pdev)
 110 {
 111         int i;
 112         struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
 113         struct led_pwm_data *leds_data;
 114
 115         leds_data = platform_get_drvdata(pdev);
 116
 117         for (i = 0; i < pdata->num_leds; i++) {
 118                 led_classdev_unregister(&leds_data[i].cdev);
 119                 pwm_free(leds_data[i].pwm);
 120         }
 121
 122         kfree(leds_data);
 123
 124         return 0;
 125 }
 126
 127 static struct platform_driver led_pwm_driver = {
 128         .probe          = led_pwm_probe,
 129         .remove         = __devexit_p(led_pwm_remove),
 130         .driver         = {
 131                 .name   = "leds_pwm",
 132                 .owner  = THIS_MODULE,
 133         },
 134 };
 135
 136 static int __init led_pwm_init(void)
 137 {
 138         return platform_driver_register(&led_pwm_driver);
 139 }
 140
 141 static void __exit led_pwm_exit(void)
 142 {
 143         platform_driver_unregister(&led_pwm_driver);
 144 }
 145
 146 module_init(led_pwm_init);
 147 module_exit(led_pwm_exit);
 148
 149 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 150 MODULE_DESCRIPTION("PWM LED driver for PXA");
 151 MODULE_LICENSE("GPL");
 152 MODULE_ALIAS("platform:leds-pwm");