1/*
2 * linux/drivers/leds-pwm.c
3 *
4 * simple PWM based LED control
5 *
6 * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de)
7 *
8 * based on leds-gpio.c by Raphael Assenat <raph@8d.com>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#include <linux/module.h>
16#include <linux/kernel.h>
17#include <linux/platform_device.h>
18#include <linux/of_platform.h>
19#include <linux/fb.h>
20#include <linux/leds.h>
21#include <linux/err.h>
22#include <linux/pwm.h>
23#include <linux/leds_pwm.h>
24#include <linux/slab.h>
25#include <linux/workqueue.h>
26
27struct led_pwm_data {
28	struct led_classdev	cdev;
29	struct pwm_device	*pwm;
30	struct work_struct	work;
31	unsigned int		active_low;
32	unsigned int		period;
33	int			duty;
34	bool			can_sleep;
35};
36
37struct led_pwm_priv {
38	int num_leds;
39	struct led_pwm_data leds[0];
40};
41
42static void __led_pwm_set(struct led_pwm_data *led_dat)
43{
44	int new_duty = led_dat->duty;
45
46	pwm_config(led_dat->pwm, new_duty, led_dat->period);
47
48	if (new_duty == 0)
49		pwm_disable(led_dat->pwm);
50	else
51		pwm_enable(led_dat->pwm);
52}
53
54static void led_pwm_work(struct work_struct *work)
55{
56	struct led_pwm_data *led_dat =
57		container_of(work, struct led_pwm_data, work);
58
59	__led_pwm_set(led_dat);
60}
61
62static void led_pwm_set(struct led_classdev *led_cdev,
63	enum led_brightness brightness)
64{
65	struct led_pwm_data *led_dat =
66		container_of(led_cdev, struct led_pwm_data, cdev);
67	unsigned int max = led_dat->cdev.max_brightness;
68	unsigned long long duty =  led_dat->period;
69
70	duty *= brightness;
71	do_div(duty, max);
72
73	if (led_dat->active_low)
74		duty = led_dat->period - duty;
75
76	led_dat->duty = duty;
77
78	if (led_dat->can_sleep)
79		schedule_work(&led_dat->work);
80	else
81		__led_pwm_set(led_dat);
82}
83
84static inline size_t sizeof_pwm_leds_priv(int num_leds)
85{
86	return sizeof(struct led_pwm_priv) +
87		      (sizeof(struct led_pwm_data) * num_leds);
88}
89
90static void led_pwm_cleanup(struct led_pwm_priv *priv)
91{
92	while (priv->num_leds--) {
93		led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
94		if (priv->leds[priv->num_leds].can_sleep)
95			cancel_work_sync(&priv->leds[priv->num_leds].work);
96	}
97}
98
99static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
100		       struct led_pwm *led, struct device_node *child)
101{
102	struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
103	int ret;
104
105	led_data->active_low = led->active_low;
106	led_data->cdev.name = led->name;
107	led_data->cdev.default_trigger = led->default_trigger;
108	led_data->cdev.brightness_set = led_pwm_set;
109	led_data->cdev.brightness = LED_OFF;
110	led_data->cdev.max_brightness = led->max_brightness;
111	led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
112
113	if (child)
114		led_data->pwm = devm_of_pwm_get(dev, child, NULL);
115	else
116		led_data->pwm = devm_pwm_get(dev, led->name);
117	if (IS_ERR(led_data->pwm)) {
118		ret = PTR_ERR(led_data->pwm);
119		dev_err(dev, "unable to request PWM for %s: %d\n",
120			led->name, ret);
121		return ret;
122	}
123
124	led_data->can_sleep = pwm_can_sleep(led_data->pwm);
125	if (led_data->can_sleep)
126		INIT_WORK(&led_data->work, led_pwm_work);
127
128	led_data->period = pwm_get_period(led_data->pwm);
129	if (!led_data->period && (led->pwm_period_ns > 0))
130		led_data->period = led->pwm_period_ns;
131
132	ret = led_classdev_register(dev, &led_data->cdev);
133	if (ret == 0) {
134		priv->num_leds++;
135	} else {
136		dev_err(dev, "failed to register PWM led for %s: %d\n",
137			led->name, ret);
138	}
139
140	return ret;
141}
142
143static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv)
144{
145	struct device_node *child;
146	struct led_pwm led;
147	int ret = 0;
148
149	memset(&led, 0, sizeof(led));
150
151	for_each_child_of_node(dev->of_node, child) {
152		led.name = of_get_property(child, "label", NULL) ? :
153			   child->name;
154
155		led.default_trigger = of_get_property(child,
156						"linux,default-trigger", NULL);
157		led.active_low = of_property_read_bool(child, "active-low");
158		of_property_read_u32(child, "max-brightness",
159				     &led.max_brightness);
160
161		ret = led_pwm_add(dev, priv, &led, child);
162		if (ret) {
163			of_node_put(child);
164			break;
165		}
166	}
167
168	return ret;
169}
170
171static int led_pwm_probe(struct platform_device *pdev)
172{
173	struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
174	struct led_pwm_priv *priv;
175	int count, i;
176	int ret = 0;
177
178	if (pdata)
179		count = pdata->num_leds;
180	else
181		count = of_get_child_count(pdev->dev.of_node);
182
183	if (!count)
184		return -EINVAL;
185
186	priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
187			    GFP_KERNEL);
188	if (!priv)
189		return -ENOMEM;
190
191	if (pdata) {
192		for (i = 0; i < count; i++) {
193			ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
194					  NULL);
195			if (ret)
196				break;
197		}
198	} else {
199		ret = led_pwm_create_of(&pdev->dev, priv);
200	}
201
202	if (ret) {
203		led_pwm_cleanup(priv);
204		return ret;
205	}
206
207	platform_set_drvdata(pdev, priv);
208
209	return 0;
210}
211
212static int led_pwm_remove(struct platform_device *pdev)
213{
214	struct led_pwm_priv *priv = platform_get_drvdata(pdev);
215
216	led_pwm_cleanup(priv);
217
218	return 0;
219}
220
221static const struct of_device_id of_pwm_leds_match[] = {
222	{ .compatible = "pwm-leds", },
223	{},
224};
225MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
226
227static struct platform_driver led_pwm_driver = {
228	.probe		= led_pwm_probe,
229	.remove		= led_pwm_remove,
230	.driver		= {
231		.name	= "leds_pwm",
232		.of_match_table = of_pwm_leds_match,
233	},
234};
235
236module_platform_driver(led_pwm_driver);
237
238MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
239MODULE_DESCRIPTION("PWM LED driver for PXA");
240MODULE_LICENSE("GPL");
241MODULE_ALIAS("platform:leds-pwm");
242