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Linux/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");
183 

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