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/platform_device.h>
  21 #include <linux/leds.h>
  22 #include <linux/delay.h>
  23 #include <linux/gpio.h>
  24 #include <linux/slab.h>
  25 #include <linux/module.h>
  26
  27 struct lt3593_led_data {
  28         struct led_classdev cdev;
  29         unsigned gpio;
  30 };
  31
  32 static int lt3593_led_set(struct led_classdev *led_cdev,
  33                            enum led_brightness value)
  34 {
  35         struct lt3593_led_data *led_dat =
  36                 container_of(led_cdev, struct lt3593_led_data, cdev);
  37         int pulses;
  38
  39         /*
  40          * The LT3593 resets its internal current level register to the maximum
  41          * level on the first falling edge on the control pin. Each following
  42          * falling edge decreases the current level by 625uA. Up to 32 pulses
  43          * can be sent, so the maximum power reduction is 20mA.
  44          * After a timeout of 128us, the value is taken from the register and
  45          * applied is to the output driver.
  46          */
  47
  48         if (value == 0) {
  49                 gpio_set_value_cansleep(led_dat->gpio, 0);
  50                 return 0;
  51         }
  52
  53         pulses = 32 - (value * 32) / 255;
  54
  55         if (pulses == 0) {
  56                 gpio_set_value_cansleep(led_dat->gpio, 0);
  57                 mdelay(1);
  58                 gpio_set_value_cansleep(led_dat->gpio, 1);
  59                 return 0;
  60         }
  61
  62         gpio_set_value_cansleep(led_dat->gpio, 1);
  63
  64         while (pulses--) {
  65                 gpio_set_value_cansleep(led_dat->gpio, 0);
  66                 udelay(1);
  67                 gpio_set_value_cansleep(led_dat->gpio, 1);
  68                 udelay(1);
  69         }
  70
  71         return 0;
  72 }
  73
  74 static int create_lt3593_led(const struct gpio_led *template,
  75         struct lt3593_led_data *led_dat, struct device *parent)
  76 {
  77         int ret, state;
  78
  79         /* skip leds on GPIOs that aren't available */
  80         if (!gpio_is_valid(template->gpio)) {
  81                 dev_info(parent, "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
  82                                 KBUILD_MODNAME, template->gpio, template->name);
  83                 return 0;
  84         }
  85
  86         led_dat->cdev.name = template->name;
  87         led_dat->cdev.default_trigger = template->default_trigger;
  88         led_dat->gpio = template->gpio;
  89
  90         led_dat->cdev.brightness_set_blocking = lt3593_led_set;
  91
  92         state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
  93         led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
  94
  95         if (!template->retain_state_suspended)
  96                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
  97
  98         ret = devm_gpio_request_one(parent, template->gpio, state ?
  99                                     GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
 100                                     template->name);
 101         if (ret < 0)
 102                 return ret;
 103
 104         ret = led_classdev_register(parent, &led_dat->cdev);
 105         if (ret < 0)
 106                 return ret;
 107
 108         dev_info(parent, "%s: registered LT3593 LED '%s' at GPIO %d\n",
 109                 KBUILD_MODNAME, template->name, template->gpio);
 110
 111         return 0;
 112 }
 113
 114 static void delete_lt3593_led(struct lt3593_led_data *led)
 115 {
 116         if (!gpio_is_valid(led->gpio))
 117                 return;
 118
 119         led_classdev_unregister(&led->cdev);
 120 }
 121
 122 static int lt3593_led_probe(struct platform_device *pdev)
 123 {
 124         struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);
 125         struct lt3593_led_data *leds_data;
 126         int i, ret = 0;
 127
 128         if (!pdata)
 129                 return -EBUSY;
 130
 131         leds_data = devm_kzalloc(&pdev->dev,
 132                         sizeof(struct lt3593_led_data) * pdata->num_leds,
 133                         GFP_KERNEL);
 134         if (!leds_data)
 135                 return -ENOMEM;
 136
 137         for (i = 0; i < pdata->num_leds; i++) {
 138                 ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
 139                                       &pdev->dev);
 140                 if (ret < 0)
 141                         goto err;
 142         }
 143
 144         platform_set_drvdata(pdev, leds_data);
 145
 146         return 0;
 147
 148 err:
 149         for (i = i - 1; i >= 0; i--)
 150                 delete_lt3593_led(&leds_data[i]);
 151
 152         return ret;
 153 }
 154
 155 static int lt3593_led_remove(struct platform_device *pdev)
 156 {
 157         int i;
 158         struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);
 159         struct lt3593_led_data *leds_data;
 160
 161         leds_data = platform_get_drvdata(pdev);
 162
 163         for (i = 0; i < pdata->num_leds; i++)
 164                 delete_lt3593_led(&leds_data[i]);
 165
 166         return 0;
 167 }
 168
 169 static struct platform_driver lt3593_led_driver = {
 170         .probe          = lt3593_led_probe,
 171         .remove         = lt3593_led_remove,
 172         .driver         = {
 173                 .name   = "leds-lt3593",
 174         },
 175 };
 176
 177 module_platform_driver(lt3593_led_driver);
 178
 179 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
 180 MODULE_DESCRIPTION("LED driver for LT3593 controllers");
 181 MODULE_LICENSE("GPL");
 182 MODULE_ALIAS("platform:leds-lt3593");