drivers/leds/leds-lt3593.c

   1 /*
   2  * LEDs driver for LT3593 controllers
   3  *
   4  * See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf
   5  *
   6  * Copyright (c) 2009 Daniel Mack <daniel@caiaq.de>
   7  *
   8  * Based on leds-gpio.c,
   9  *
  10  *   Copyright (C) 2007 8D Technologies inc.
  11  *   Raphael Assenat <raph@8d.com>
  12  *   Copyright (C) 2008 Freescale Semiconductor, Inc.
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License version 2 as
  16  * published by the Free Software Foundation.
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/init.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/leds.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/delay.h>
  25 #include <linux/gpio.h>
  26
  27 struct lt3593_led_data {
  28         struct led_classdev cdev;
  29         unsigned gpio;
  30         struct work_struct work;
  31         u8 new_level;
  32 };
  33
  34 static void lt3593_led_work(struct work_struct *work)
  35 {
  36         int pulses;
  37         struct lt3593_led_data *led_dat =
  38                 container_of(work, struct lt3593_led_data, work);
  39
  40         /*
  41          * The LT3593 resets its internal current level register to the maximum
  42          * level on the first falling edge on the control pin. Each following
  43          * falling edge decreases the current level by 625uA. Up to 32 pulses
  44          * can be sent, so the maximum power reduction is 20mA.
  45          * After a timeout of 128us, the value is taken from the register and
  46          * applied is to the output driver.
  47          */
  48
  49         if (led_dat->new_level == 0) {
  50                 gpio_set_value_cansleep(led_dat->gpio, 0);
  51                 return;
  52         }
  53
  54         pulses = 32 - (led_dat->new_level * 32) / 255;
  55
  56         if (pulses == 0) {
  57                 gpio_set_value_cansleep(led_dat->gpio, 0);
  58                 mdelay(1);
  59                 gpio_set_value_cansleep(led_dat->gpio, 1);
  60                 return;
  61         }
  62
  63         gpio_set_value_cansleep(led_dat->gpio, 1);
  64
  65         while (pulses--) {
  66                 gpio_set_value_cansleep(led_dat->gpio, 0);
  67                 udelay(1);
  68                 gpio_set_value_cansleep(led_dat->gpio, 1);
  69                 udelay(1);
  70         }
  71 }
  72
  73 static void lt3593_led_set(struct led_classdev *led_cdev,
  74         enum led_brightness value)
  75 {
  76         struct lt3593_led_data *led_dat =
  77                 container_of(led_cdev, struct lt3593_led_data, cdev);
  78
  79         led_dat->new_level = value;
  80         schedule_work(&led_dat->work);
  81 }
  82
  83 static int __devinit create_lt3593_led(const struct gpio_led *template,
  84         struct lt3593_led_data *led_dat, struct device *parent)
  85 {
  86         int ret, state;
  87
  88         /* skip leds on GPIOs that aren't available */
  89         if (!gpio_is_valid(template->gpio)) {
  90                 printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
  91                                 KBUILD_MODNAME, template->gpio, template->name);
  92                 return 0;
  93         }
  94
  95         ret = gpio_request(template->gpio, template->name);
  96         if (ret < 0)
  97                 return ret;
  98
  99         led_dat->cdev.name = template->name;
 100         led_dat->cdev.default_trigger = template->default_trigger;
 101         led_dat->gpio = template->gpio;
 102
 103         led_dat->cdev.brightness_set = lt3593_led_set;
 104
 105         state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
 106         led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
 107
 108         if (!template->retain_state_suspended)
 109                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 110
 111         ret = gpio_direction_output(led_dat->gpio, state);
 112         if (ret < 0)
 113                 goto err;
 114
 115         INIT_WORK(&led_dat->work, lt3593_led_work);
 116
 117         ret = led_classdev_register(parent, &led_dat->cdev);
 118         if (ret < 0)
 119                 goto err;
 120
 121         printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n",
 122                 KBUILD_MODNAME, template->name, template->gpio);
 123
 124         return 0;
 125
 126 err:
 127         gpio_free(led_dat->gpio);
 128         return ret;
 129 }
 130
 131 static void delete_lt3593_led(struct lt3593_led_data *led)
 132 {
 133         if (!gpio_is_valid(led->gpio))
 134                 return;
 135
 136         led_classdev_unregister(&led->cdev);
 137         cancel_work_sync(&led->work);
 138         gpio_free(led->gpio);
 139 }
 140
 141 static int __devinit lt3593_led_probe(struct platform_device *pdev)
 142 {
 143         struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
 144         struct lt3593_led_data *leds_data;
 145         int i, ret = 0;
 146
 147         if (!pdata)
 148                 return -EBUSY;
 149
 150         leds_data = kzalloc(sizeof(struct lt3593_led_data) * pdata->num_leds,
 151                                 GFP_KERNEL);
 152         if (!leds_data)
 153                 return -ENOMEM;
 154
 155         for (i = 0; i < pdata->num_leds; i++) {
 156                 ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
 157                                       &pdev->dev);
 158                 if (ret < 0)
 159                         goto err;
 160         }
 161
 162         platform_set_drvdata(pdev, leds_data);
 163
 164         return 0;
 165
 166 err:
 167         for (i = i - 1; i >= 0; i--)
 168                 delete_lt3593_led(&leds_data[i]);
 169
 170         kfree(leds_data);
 171
 172         return ret;
 173 }
 174
 175 static int __devexit lt3593_led_remove(struct platform_device *pdev)
 176 {
 177         int i;
 178         struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
 179         struct lt3593_led_data *leds_data;
 180
 181         leds_data = platform_get_drvdata(pdev);
 182
 183         for (i = 0; i < pdata->num_leds; i++)
 184                 delete_lt3593_led(&leds_data[i]);
 185
 186         kfree(leds_data);
 187
 188         return 0;
 189 }
 190
 191 static struct platform_driver lt3593_led_driver = {
 192         .probe          = lt3593_led_probe,
 193         .remove         = __devexit_p(lt3593_led_remove),
 194         .driver         = {
 195                 .name   = "leds-lt3593",
 196                 .owner  = THIS_MODULE,
 197         },
 198 };
 199
 200 MODULE_ALIAS("platform:leds-lt3593");
 201
 202 static int __init lt3593_led_init(void)
 203 {
 204         return platform_driver_register(&lt3593_led_driver);
 205 }
 206
 207 static void __exit lt3593_led_exit(void)
 208 {
 209         platform_driver_unregister(&lt3593_led_driver);
 210 }
 211
 212 module_init(lt3593_led_init);
 213 module_exit(lt3593_led_exit);
 214
 215 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
 216 MODULE_DESCRIPTION("LED driver for LT3593 controllers");
 217 MODULE_LICENSE("GPL");