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