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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/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, state ?
110                                     GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
111                                     template->name);
112         if (ret < 0)
113                 return ret;
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                 return ret;
120 
121         dev_info(parent, "%s: registered LT3593 LED '%s' at GPIO %d\n",
122                 KBUILD_MODNAME, template->name, template->gpio);
123 
124         return 0;
125 }
126 
127 static void delete_lt3593_led(struct lt3593_led_data *led)
128 {
129         if (!gpio_is_valid(led->gpio))
130                 return;
131 
132         led_classdev_unregister(&led->cdev);
133         cancel_work_sync(&led->work);
134 }
135 
136 static int lt3593_led_probe(struct platform_device *pdev)
137 {
138         struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);
139         struct lt3593_led_data *leds_data;
140         int i, ret = 0;
141 
142         if (!pdata)
143                 return -EBUSY;
144 
145         leds_data = devm_kzalloc(&pdev->dev,
146                         sizeof(struct lt3593_led_data) * pdata->num_leds,
147                         GFP_KERNEL);
148         if (!leds_data)
149                 return -ENOMEM;
150 
151         for (i = 0; i < pdata->num_leds; i++) {
152                 ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
153                                       &pdev->dev);
154                 if (ret < 0)
155                         goto err;
156         }
157 
158         platform_set_drvdata(pdev, leds_data);
159 
160         return 0;
161 
162 err:
163         for (i = i - 1; i >= 0; i--)
164                 delete_lt3593_led(&leds_data[i]);
165 
166         return ret;
167 }
168 
169 static int lt3593_led_remove(struct platform_device *pdev)
170 {
171         int i;
172         struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);
173         struct lt3593_led_data *leds_data;
174 
175         leds_data = platform_get_drvdata(pdev);
176 
177         for (i = 0; i < pdata->num_leds; i++)
178                 delete_lt3593_led(&leds_data[i]);
179 
180         return 0;
181 }
182 
183 static struct platform_driver lt3593_led_driver = {
184         .probe          = lt3593_led_probe,
185         .remove         = lt3593_led_remove,
186         .driver         = {
187                 .name   = "leds-lt3593",
188                 .owner  = THIS_MODULE,
189         },
190 };
191 
192 module_platform_driver(lt3593_led_driver);
193 
194 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
195 MODULE_DESCRIPTION("LED driver for LT3593 controllers");
196 MODULE_LICENSE("GPL");
197 MODULE_ALIAS("platform:leds-lt3593");
198 

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