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