1/*
2 * leds-regulator.c - LED class driver for regulator driven LEDs.
3 *
4 * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
5 *
6 * Inspired by leds-wm8350 driver.
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 */
13
14#include <linux/module.h>
15#include <linux/err.h>
16#include <linux/slab.h>
17#include <linux/workqueue.h>
18#include <linux/leds.h>
19#include <linux/leds-regulator.h>
20#include <linux/platform_device.h>
21#include <linux/regulator/consumer.h>
22
23#define to_regulator_led(led_cdev) \
24	container_of(led_cdev, struct regulator_led, cdev)
25
26struct regulator_led {
27	struct led_classdev cdev;
28	enum led_brightness value;
29	int enabled;
30	struct mutex mutex;
31	struct work_struct work;
32
33	struct regulator *vcc;
34};
35
36static inline int led_regulator_get_max_brightness(struct regulator *supply)
37{
38	int ret;
39	int voltage = regulator_list_voltage(supply, 0);
40
41	if (voltage <= 0)
42		return 1;
43
44	/* even if regulator can't change voltages,
45	 * we still assume it can change status
46	 * and the LED can be turned on and off.
47	 */
48	ret = regulator_set_voltage(supply, voltage, voltage);
49	if (ret < 0)
50		return 1;
51
52	return regulator_count_voltages(supply);
53}
54
55static int led_regulator_get_voltage(struct regulator *supply,
56		enum led_brightness brightness)
57{
58	if (brightness == 0)
59		return -EINVAL;
60
61	return regulator_list_voltage(supply, brightness - 1);
62}
63
64
65static void regulator_led_enable(struct regulator_led *led)
66{
67	int ret;
68
69	if (led->enabled)
70		return;
71
72	ret = regulator_enable(led->vcc);
73	if (ret != 0) {
74		dev_err(led->cdev.dev, "Failed to enable vcc: %d\n", ret);
75		return;
76	}
77
78	led->enabled = 1;
79}
80
81static void regulator_led_disable(struct regulator_led *led)
82{
83	int ret;
84
85	if (!led->enabled)
86		return;
87
88	ret = regulator_disable(led->vcc);
89	if (ret != 0) {
90		dev_err(led->cdev.dev, "Failed to disable vcc: %d\n", ret);
91		return;
92	}
93
94	led->enabled = 0;
95}
96
97static void regulator_led_set_value(struct regulator_led *led)
98{
99	int voltage;
100	int ret;
101
102	mutex_lock(&led->mutex);
103
104	if (led->value == LED_OFF) {
105		regulator_led_disable(led);
106		goto out;
107	}
108
109	if (led->cdev.max_brightness > 1) {
110		voltage = led_regulator_get_voltage(led->vcc, led->value);
111		dev_dbg(led->cdev.dev, "brightness: %d voltage: %d\n",
112				led->value, voltage);
113
114		ret = regulator_set_voltage(led->vcc, voltage, voltage);
115		if (ret != 0)
116			dev_err(led->cdev.dev, "Failed to set voltage %d: %d\n",
117				voltage, ret);
118	}
119
120	regulator_led_enable(led);
121
122out:
123	mutex_unlock(&led->mutex);
124}
125
126static void led_work(struct work_struct *work)
127{
128	struct regulator_led *led;
129
130	led = container_of(work, struct regulator_led, work);
131	regulator_led_set_value(led);
132}
133
134static void regulator_led_brightness_set(struct led_classdev *led_cdev,
135			   enum led_brightness value)
136{
137	struct regulator_led *led = to_regulator_led(led_cdev);
138
139	led->value = value;
140	schedule_work(&led->work);
141}
142
143static int regulator_led_probe(struct platform_device *pdev)
144{
145	struct led_regulator_platform_data *pdata =
146			dev_get_platdata(&pdev->dev);
147	struct regulator_led *led;
148	struct regulator *vcc;
149	int ret = 0;
150
151	if (pdata == NULL) {
152		dev_err(&pdev->dev, "no platform data\n");
153		return -ENODEV;
154	}
155
156	vcc = devm_regulator_get_exclusive(&pdev->dev, "vled");
157	if (IS_ERR(vcc)) {
158		dev_err(&pdev->dev, "Cannot get vcc for %s\n", pdata->name);
159		return PTR_ERR(vcc);
160	}
161
162	led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
163	if (led == NULL)
164		return -ENOMEM;
165
166	led->cdev.max_brightness = led_regulator_get_max_brightness(vcc);
167	if (pdata->brightness > led->cdev.max_brightness) {
168		dev_err(&pdev->dev, "Invalid default brightness %d\n",
169				pdata->brightness);
170		return -EINVAL;
171	}
172	led->value = pdata->brightness;
173
174	led->cdev.brightness_set = regulator_led_brightness_set;
175	led->cdev.name = pdata->name;
176	led->cdev.flags |= LED_CORE_SUSPENDRESUME;
177	led->vcc = vcc;
178
179	/* to handle correctly an already enabled regulator */
180	if (regulator_is_enabled(led->vcc))
181		led->enabled = 1;
182
183	mutex_init(&led->mutex);
184	INIT_WORK(&led->work, led_work);
185
186	platform_set_drvdata(pdev, led);
187
188	ret = led_classdev_register(&pdev->dev, &led->cdev);
189	if (ret < 0) {
190		cancel_work_sync(&led->work);
191		return ret;
192	}
193
194	/* to expose the default value to userspace */
195	led->cdev.brightness = led->value;
196
197	/* Set the default led status */
198	regulator_led_set_value(led);
199
200	return 0;
201}
202
203static int regulator_led_remove(struct platform_device *pdev)
204{
205	struct regulator_led *led = platform_get_drvdata(pdev);
206
207	led_classdev_unregister(&led->cdev);
208	cancel_work_sync(&led->work);
209	regulator_led_disable(led);
210	return 0;
211}
212
213static struct platform_driver regulator_led_driver = {
214	.driver = {
215		   .name  = "leds-regulator",
216		   },
217	.probe  = regulator_led_probe,
218	.remove = regulator_led_remove,
219};
220
221module_platform_driver(regulator_led_driver);
222
223MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
224MODULE_DESCRIPTION("Regulator driven LED driver");
225MODULE_LICENSE("GPL");
226MODULE_ALIAS("platform:leds-regulator");
227