Root/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
29struct lt3593_led_data {
30    struct led_classdev cdev;
31    unsigned gpio;
32    struct work_struct work;
33    u8 new_level;
34};
35
36static 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
75static 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
85static 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
126static 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
135static 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
161err:
162    for (i = i - 1; i >= 0; i--)
163        delete_lt3593_led(&leds_data[i]);
164
165    return ret;
166}
167
168static 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
182static 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
191module_platform_driver(lt3593_led_driver);
192
193MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
194MODULE_DESCRIPTION("LED driver for LT3593 controllers");
195MODULE_LICENSE("GPL");
196MODULE_ALIAS("platform:leds-lt3593");
197

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