leds-lt3593.c revision 87aae1ea82f93f0f00cb955044ea1db3501cf233 
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, 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
127static 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
136static 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
162err:
163	for (i = i - 1; i >= 0; i--)
164		delete_lt3593_led(&leds_data[i]);
165
166	return ret;
167}
168
169static 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
183static 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
192module_platform_driver(lt3593_led_driver);
193
194MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
195MODULE_DESCRIPTION("LED driver for LT3593 controllers");
196MODULE_LICENSE("GPL");
197MODULE_ALIAS("platform:leds-lt3593");
198