leds-lt3593.c revision 5a0e3ad6af8660be21ca98a971cd00f331318c05 
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
28struct lt3593_led_data {
29	struct led_classdev cdev;
30	unsigned gpio;
31	struct work_struct work;
32	u8 new_level;
33};
34
35static void lt3593_led_work(struct work_struct *work)
36{
37	int pulses;
38	struct lt3593_led_data *led_dat =
39		container_of(work, struct lt3593_led_data, work);
40
41	/*
42	 * The LT3593 resets its internal current level register to the maximum
43	 * level on the first falling edge on the control pin. Each following
44	 * falling edge decreases the current level by 625uA. Up to 32 pulses
45	 * can be sent, so the maximum power reduction is 20mA.
46	 * After a timeout of 128us, the value is taken from the register and
47	 * applied is to the output driver.
48	 */
49
50	if (led_dat->new_level == 0) {
51		gpio_set_value_cansleep(led_dat->gpio, 0);
52		return;
53	}
54
55	pulses = 32 - (led_dat->new_level * 32) / 255;
56
57	if (pulses == 0) {
58		gpio_set_value_cansleep(led_dat->gpio, 0);
59		mdelay(1);
60		gpio_set_value_cansleep(led_dat->gpio, 1);
61		return;
62	}
63
64	gpio_set_value_cansleep(led_dat->gpio, 1);
65
66	while (pulses--) {
67		gpio_set_value_cansleep(led_dat->gpio, 0);
68		udelay(1);
69		gpio_set_value_cansleep(led_dat->gpio, 1);
70		udelay(1);
71	}
72}
73
74static void lt3593_led_set(struct led_classdev *led_cdev,
75	enum led_brightness value)
76{
77	struct lt3593_led_data *led_dat =
78		container_of(led_cdev, struct lt3593_led_data, cdev);
79
80	led_dat->new_level = value;
81	schedule_work(&led_dat->work);
82}
83
84static int __devinit create_lt3593_led(const struct gpio_led *template,
85	struct lt3593_led_data *led_dat, struct device *parent)
86{
87	int ret, state;
88
89	/* skip leds on GPIOs that aren't available */
90	if (!gpio_is_valid(template->gpio)) {
91		printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
92				KBUILD_MODNAME, template->gpio, template->name);
93		return 0;
94	}
95
96	ret = gpio_request(template->gpio, template->name);
97	if (ret < 0)
98		return ret;
99
100	led_dat->cdev.name = template->name;
101	led_dat->cdev.default_trigger = template->default_trigger;
102	led_dat->gpio = template->gpio;
103
104	led_dat->cdev.brightness_set = lt3593_led_set;
105
106	state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
107	led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
108
109	if (!template->retain_state_suspended)
110		led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
111
112	ret = gpio_direction_output(led_dat->gpio, state);
113	if (ret < 0)
114		goto err;
115
116	INIT_WORK(&led_dat->work, lt3593_led_work);
117
118	ret = led_classdev_register(parent, &led_dat->cdev);
119	if (ret < 0)
120		goto err;
121
122	printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n",
123		KBUILD_MODNAME, template->name, template->gpio);
124
125	return 0;
126
127err:
128	gpio_free(led_dat->gpio);
129	return ret;
130}
131
132static void delete_lt3593_led(struct lt3593_led_data *led)
133{
134	if (!gpio_is_valid(led->gpio))
135		return;
136
137	led_classdev_unregister(&led->cdev);
138	cancel_work_sync(&led->work);
139	gpio_free(led->gpio);
140}
141
142static int __devinit lt3593_led_probe(struct platform_device *pdev)
143{
144	struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
145	struct lt3593_led_data *leds_data;
146	int i, ret = 0;
147
148	if (!pdata)
149		return -EBUSY;
150
151	leds_data = kzalloc(sizeof(struct lt3593_led_data) * pdata->num_leds,
152				GFP_KERNEL);
153	if (!leds_data)
154		return -ENOMEM;
155
156	for (i = 0; i < pdata->num_leds; i++) {
157		ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
158				      &pdev->dev);
159		if (ret < 0)
160			goto err;
161	}
162
163	platform_set_drvdata(pdev, leds_data);
164
165	return 0;
166
167err:
168	for (i = i - 1; i >= 0; i--)
169		delete_lt3593_led(&leds_data[i]);
170
171	kfree(leds_data);
172
173	return ret;
174}
175
176static int __devexit lt3593_led_remove(struct platform_device *pdev)
177{
178	int i;
179	struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
180	struct lt3593_led_data *leds_data;
181
182	leds_data = platform_get_drvdata(pdev);
183
184	for (i = 0; i < pdata->num_leds; i++)
185		delete_lt3593_led(&leds_data[i]);
186
187	kfree(leds_data);
188
189	return 0;
190}
191
192static struct platform_driver lt3593_led_driver = {
193	.probe		= lt3593_led_probe,
194	.remove		= __devexit_p(lt3593_led_remove),
195	.driver		= {
196		.name	= "leds-lt3593",
197		.owner	= THIS_MODULE,
198	},
199};
200
201MODULE_ALIAS("platform:leds-lt3593");
202
203static int __init lt3593_led_init(void)
204{
205	return platform_driver_register(&lt3593_led_driver);
206}
207
208static void __exit lt3593_led_exit(void)
209{
210	platform_driver_unregister(&lt3593_led_driver);
211}
212
213module_init(lt3593_led_init);
214module_exit(lt3593_led_exit);
215
216MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
217MODULE_DESCRIPTION("LED driver for LT3593 controllers");
218MODULE_LICENSE("GPL");
219