Root/drivers/leds/leds-pwm.c

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/init.h>
18#include <linux/platform_device.h>
19#include <linux/of_platform.h>
20#include <linux/fb.h>
21#include <linux/leds.h>
22#include <linux/err.h>
23#include <linux/pwm.h>
24#include <linux/leds_pwm.h>
25#include <linux/slab.h>
26
27struct led_pwm_data {
28    struct led_classdev cdev;
29    struct pwm_device *pwm;
30    unsigned int active_low;
31    unsigned int period;
32};
33
34struct led_pwm_priv {
35    int num_leds;
36    struct led_pwm_data leds[0];
37};
38
39static void led_pwm_set(struct led_classdev *led_cdev,
40    enum led_brightness brightness)
41{
42    struct led_pwm_data *led_dat =
43        container_of(led_cdev, struct led_pwm_data, cdev);
44    unsigned int max = led_dat->cdev.max_brightness;
45    unsigned int period = led_dat->period;
46
47    if (brightness == 0) {
48        pwm_config(led_dat->pwm, 0, period);
49        pwm_disable(led_dat->pwm);
50    } else {
51        pwm_config(led_dat->pwm, brightness * period / max, period);
52        pwm_enable(led_dat->pwm);
53    }
54}
55
56static inline size_t sizeof_pwm_leds_priv(int num_leds)
57{
58    return sizeof(struct led_pwm_priv) +
59              (sizeof(struct led_pwm_data) * num_leds);
60}
61
62static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev)
63{
64    struct device_node *node = pdev->dev.of_node;
65    struct device_node *child;
66    struct led_pwm_priv *priv;
67    int count, ret;
68
69    /* count LEDs in this device, so we know how much to allocate */
70    count = of_get_child_count(node);
71    if (!count)
72        return NULL;
73
74    priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
75                GFP_KERNEL);
76    if (!priv)
77        return NULL;
78
79    for_each_child_of_node(node, child) {
80        struct led_pwm_data *led_dat = &priv->leds[priv->num_leds];
81
82        led_dat->cdev.name = of_get_property(child, "label",
83                             NULL) ? : child->name;
84
85        led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL);
86        if (IS_ERR(led_dat->pwm)) {
87            dev_err(&pdev->dev, "unable to request PWM for %s\n",
88                led_dat->cdev.name);
89            goto err;
90        }
91        /* Get the period from PWM core when n*/
92        led_dat->period = pwm_get_period(led_dat->pwm);
93
94        led_dat->cdev.default_trigger = of_get_property(child,
95                        "linux,default-trigger", NULL);
96        of_property_read_u32(child, "max-brightness",
97                     &led_dat->cdev.max_brightness);
98
99        led_dat->cdev.brightness_set = led_pwm_set;
100        led_dat->cdev.brightness = LED_OFF;
101        led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
102
103        ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
104        if (ret < 0) {
105            dev_err(&pdev->dev, "failed to register for %s\n",
106                led_dat->cdev.name);
107            of_node_put(child);
108            goto err;
109        }
110        priv->num_leds++;
111    }
112
113    return priv;
114err:
115    while (priv->num_leds--)
116        led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
117
118    return NULL;
119}
120
121static int led_pwm_probe(struct platform_device *pdev)
122{
123    struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
124    struct led_pwm_priv *priv;
125    int i, ret = 0;
126
127    if (pdata && pdata->num_leds) {
128        priv = devm_kzalloc(&pdev->dev,
129                    sizeof_pwm_leds_priv(pdata->num_leds),
130                    GFP_KERNEL);
131        if (!priv)
132            return -ENOMEM;
133
134        for (i = 0; i < pdata->num_leds; i++) {
135            struct led_pwm *cur_led = &pdata->leds[i];
136            struct led_pwm_data *led_dat = &priv->leds[i];
137
138            led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name);
139            if (IS_ERR(led_dat->pwm)) {
140                ret = PTR_ERR(led_dat->pwm);
141                dev_err(&pdev->dev,
142                    "unable to request PWM for %s\n",
143                    cur_led->name);
144                goto err;
145            }
146
147            led_dat->cdev.name = cur_led->name;
148            led_dat->cdev.default_trigger = cur_led->default_trigger;
149            led_dat->active_low = cur_led->active_low;
150            led_dat->period = cur_led->pwm_period_ns;
151            led_dat->cdev.brightness_set = led_pwm_set;
152            led_dat->cdev.brightness = LED_OFF;
153            led_dat->cdev.max_brightness = cur_led->max_brightness;
154            led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
155
156            ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
157            if (ret < 0)
158                goto err;
159        }
160        priv->num_leds = pdata->num_leds;
161    } else {
162        priv = led_pwm_create_of(pdev);
163        if (!priv)
164            return -ENODEV;
165    }
166
167    platform_set_drvdata(pdev, priv);
168
169    return 0;
170
171err:
172    while (i--)
173        led_classdev_unregister(&priv->leds[i].cdev);
174
175    return ret;
176}
177
178static int led_pwm_remove(struct platform_device *pdev)
179{
180    struct led_pwm_priv *priv = platform_get_drvdata(pdev);
181    int i;
182
183    for (i = 0; i < priv->num_leds; i++)
184        led_classdev_unregister(&priv->leds[i].cdev);
185
186    return 0;
187}
188
189static const struct of_device_id of_pwm_leds_match[] = {
190    { .compatible = "pwm-leds", },
191    {},
192};
193MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
194
195static struct platform_driver led_pwm_driver = {
196    .probe = led_pwm_probe,
197    .remove = led_pwm_remove,
198    .driver = {
199        .name = "leds_pwm",
200        .owner = THIS_MODULE,
201        .of_match_table = of_match_ptr(of_pwm_leds_match),
202    },
203};
204
205module_platform_driver(led_pwm_driver);
206
207MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
208MODULE_DESCRIPTION("PWM LED driver for PXA");
209MODULE_LICENSE("GPL");
210MODULE_ALIAS("platform:leds-pwm");
211

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