summaryrefslogtreecommitdiffstats
path: root/drivers/leds/leds-lt3593.c
blob: ca48a7d5502d35fb919de639a4ddb067b6f80baf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
/*
 * LEDs driver for LT3593 controllers
 *
 * See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf
 *
 * Copyright (c) 2009 Daniel Mack <daniel@caiaq.de>
 *
 * Based on leds-gpio.c,
 *
 *   Copyright (C) 2007 8D Technologies inc.
 *   Raphael Assenat <raph@8d.com>
 *   Copyright (C) 2008 Freescale Semiconductor, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/leds.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/module.h>

struct lt3593_led_data {
	struct led_classdev cdev;
	unsigned gpio;
	struct work_struct work;
	u8 new_level;
};

static void lt3593_led_work(struct work_struct *work)
{
	int pulses;
	struct lt3593_led_data *led_dat =
		container_of(work, struct lt3593_led_data, work);

	/*
	 * The LT3593 resets its internal current level register to the maximum
	 * level on the first falling edge on the control pin. Each following
	 * falling edge decreases the current level by 625uA. Up to 32 pulses
	 * can be sent, so the maximum power reduction is 20mA.
	 * After a timeout of 128us, the value is taken from the register and
	 * applied is to the output driver.
	 */

	if (led_dat->new_level == 0) {
		gpio_set_value_cansleep(led_dat->gpio, 0);
		return;
	}

	pulses = 32 - (led_dat->new_level * 32) / 255;

	if (pulses == 0) {
		gpio_set_value_cansleep(led_dat->gpio, 0);
		mdelay(1);
		gpio_set_value_cansleep(led_dat->gpio, 1);
		return;
	}

	gpio_set_value_cansleep(led_dat->gpio, 1);

	while (pulses--) {
		gpio_set_value_cansleep(led_dat->gpio, 0);
		udelay(1);
		gpio_set_value_cansleep(led_dat->gpio, 1);
		udelay(1);
	}
}

static void lt3593_led_set(struct led_classdev *led_cdev,
	enum led_brightness value)
{
	struct lt3593_led_data *led_dat =
		container_of(led_cdev, struct lt3593_led_data, cdev);

	led_dat->new_level = value;
	schedule_work(&led_dat->work);
}

static int create_lt3593_led(const struct gpio_led *template,
	struct lt3593_led_data *led_dat, struct device *parent)
{
	int ret, state;

	/* skip leds on GPIOs that aren't available */
	if (!gpio_is_valid(template->gpio)) {
		dev_info(parent, "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
				KBUILD_MODNAME, template->gpio, template->name);
		return 0;
	}

	led_dat->cdev.name = template->name;
	led_dat->cdev.default_trigger = template->default_trigger;
	led_dat->gpio = template->gpio;

	led_dat->cdev.brightness_set = lt3593_led_set;

	state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
	led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;

	if (!template->retain_state_suspended)
		led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;

	ret = devm_gpio_request_one(parent, template->gpio, state ?
				    GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
				    template->name);
	if (ret < 0)
		return ret;

	INIT_WORK(&led_dat->work, lt3593_led_work);

	ret = led_classdev_register(parent, &led_dat->cdev);
	if (ret < 0)
		return ret;

	dev_info(parent, "%s: registered LT3593 LED '%s' at GPIO %d\n",
		KBUILD_MODNAME, template->name, template->gpio);

	return 0;
}

static void delete_lt3593_led(struct lt3593_led_data *led)
{
	if (!gpio_is_valid(led->gpio))
		return;

	led_classdev_unregister(&led->cdev);
	cancel_work_sync(&led->work);
}

static int lt3593_led_probe(struct platform_device *pdev)
{
	struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
	struct lt3593_led_data *leds_data;
	int i, ret = 0;

	if (!pdata)
		return -EBUSY;

	leds_data = devm_kzalloc(&pdev->dev,
			sizeof(struct lt3593_led_data) * pdata->num_leds,
			GFP_KERNEL);
	if (!leds_data)
		return -ENOMEM;

	for (i = 0; i < pdata->num_leds; i++) {
		ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
				      &pdev->dev);
		if (ret < 0)
			goto err;
	}

	platform_set_drvdata(pdev, leds_data);

	return 0;

err:
	for (i = i - 1; i >= 0; i--)
		delete_lt3593_led(&leds_data[i]);

	return ret;
}

static int lt3593_led_remove(struct platform_device *pdev)
{
	int i;
	struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
	struct lt3593_led_data *leds_data;

	leds_data = platform_get_drvdata(pdev);

	for (i = 0; i < pdata->num_leds; i++)
		delete_lt3593_led(&leds_data[i]);

	return 0;
}

static struct platform_driver lt3593_led_driver = {
	.probe		= lt3593_led_probe,
	.remove		= lt3593_led_remove,
	.driver		= {
		.name	= "leds-lt3593",
		.owner	= THIS_MODULE,
	},
};

module_platform_driver(lt3593_led_driver);

MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
MODULE_DESCRIPTION("LED driver for LT3593 controllers");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:leds-lt3593");
OpenPOWER on IntegriCloud