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Linux/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/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 
 26 struct led_pwm_data {
 27         struct led_classdev     cdev;
 28         struct pwm_device       *pwm;
 29         unsigned int            active_low;
 30         unsigned int            period;
 31         int                     duty;
 32         bool                    can_sleep;
 33 };
 34 
 35 struct led_pwm_priv {
 36         int num_leds;
 37         struct led_pwm_data leds[0];
 38 };
 39 
 40 static void __led_pwm_set(struct led_pwm_data *led_dat)
 41 {
 42         int new_duty = led_dat->duty;
 43 
 44         pwm_config(led_dat->pwm, new_duty, led_dat->period);
 45 
 46         if (new_duty == 0)
 47                 pwm_disable(led_dat->pwm);
 48         else
 49                 pwm_enable(led_dat->pwm);
 50 }
 51 
 52 static void led_pwm_set(struct led_classdev *led_cdev,
 53         enum led_brightness brightness)
 54 {
 55         struct led_pwm_data *led_dat =
 56                 container_of(led_cdev, struct led_pwm_data, cdev);
 57         unsigned int max = led_dat->cdev.max_brightness;
 58         unsigned long long duty =  led_dat->period;
 59 
 60         duty *= brightness;
 61         do_div(duty, max);
 62 
 63         if (led_dat->active_low)
 64                 duty = led_dat->period - duty;
 65 
 66         led_dat->duty = duty;
 67 
 68         __led_pwm_set(led_dat);
 69 }
 70 
 71 static int led_pwm_set_blocking(struct led_classdev *led_cdev,
 72         enum led_brightness brightness)
 73 {
 74         led_pwm_set(led_cdev, brightness);
 75         return 0;
 76 }
 77 
 78 static inline size_t sizeof_pwm_leds_priv(int num_leds)
 79 {
 80         return sizeof(struct led_pwm_priv) +
 81                       (sizeof(struct led_pwm_data) * num_leds);
 82 }
 83 
 84 static void led_pwm_cleanup(struct led_pwm_priv *priv)
 85 {
 86         while (priv->num_leds--)
 87                 led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
 88 }
 89 
 90 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
 91                        struct led_pwm *led, struct device_node *child)
 92 {
 93         struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
 94         int ret;
 95 
 96         led_data->active_low = led->active_low;
 97         led_data->cdev.name = led->name;
 98         led_data->cdev.default_trigger = led->default_trigger;
 99         led_data->cdev.brightness = LED_OFF;
100         led_data->cdev.max_brightness = led->max_brightness;
101         led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
102 
103         if (child)
104                 led_data->pwm = devm_of_pwm_get(dev, child, NULL);
105         else
106                 led_data->pwm = devm_pwm_get(dev, led->name);
107         if (IS_ERR(led_data->pwm)) {
108                 ret = PTR_ERR(led_data->pwm);
109                 dev_err(dev, "unable to request PWM for %s: %d\n",
110                         led->name, ret);
111                 return ret;
112         }
113 
114         led_data->can_sleep = pwm_can_sleep(led_data->pwm);
115         if (!led_data->can_sleep)
116                 led_data->cdev.brightness_set = led_pwm_set;
117         else
118                 led_data->cdev.brightness_set_blocking = led_pwm_set_blocking;
119 
120         led_data->period = pwm_get_period(led_data->pwm);
121         if (!led_data->period && (led->pwm_period_ns > 0))
122                 led_data->period = led->pwm_period_ns;
123 
124         ret = led_classdev_register(dev, &led_data->cdev);
125         if (ret == 0) {
126                 priv->num_leds++;
127                 led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
128         } else {
129                 dev_err(dev, "failed to register PWM led for %s: %d\n",
130                         led->name, ret);
131         }
132 
133         return ret;
134 }
135 
136 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv)
137 {
138         struct device_node *child;
139         struct led_pwm led;
140         int ret = 0;
141 
142         memset(&led, 0, sizeof(led));
143 
144         for_each_child_of_node(dev->of_node, child) {
145                 led.name = of_get_property(child, "label", NULL) ? :
146                            child->name;
147 
148                 led.default_trigger = of_get_property(child,
149                                                 "linux,default-trigger", NULL);
150                 led.active_low = of_property_read_bool(child, "active-low");
151                 of_property_read_u32(child, "max-brightness",
152                                      &led.max_brightness);
153 
154                 ret = led_pwm_add(dev, priv, &led, child);
155                 if (ret) {
156                         of_node_put(child);
157                         break;
158                 }
159         }
160 
161         return ret;
162 }
163 
164 static int led_pwm_probe(struct platform_device *pdev)
165 {
166         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
167         struct led_pwm_priv *priv;
168         int count, i;
169         int ret = 0;
170 
171         if (pdata)
172                 count = pdata->num_leds;
173         else
174                 count = of_get_child_count(pdev->dev.of_node);
175 
176         if (!count)
177                 return -EINVAL;
178 
179         priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
180                             GFP_KERNEL);
181         if (!priv)
182                 return -ENOMEM;
183 
184         if (pdata) {
185                 for (i = 0; i < count; i++) {
186                         ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
187                                           NULL);
188                         if (ret)
189                                 break;
190                 }
191         } else {
192                 ret = led_pwm_create_of(&pdev->dev, priv);
193         }
194 
195         if (ret) {
196                 led_pwm_cleanup(priv);
197                 return ret;
198         }
199 
200         platform_set_drvdata(pdev, priv);
201 
202         return 0;
203 }
204 
205 static int led_pwm_remove(struct platform_device *pdev)
206 {
207         struct led_pwm_priv *priv = platform_get_drvdata(pdev);
208 
209         led_pwm_cleanup(priv);
210 
211         return 0;
212 }
213 
214 static const struct of_device_id of_pwm_leds_match[] = {
215         { .compatible = "pwm-leds", },
216         {},
217 };
218 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
219 
220 static struct platform_driver led_pwm_driver = {
221         .probe          = led_pwm_probe,
222         .remove         = led_pwm_remove,
223         .driver         = {
224                 .name   = "leds_pwm",
225                 .of_match_table = of_pwm_leds_match,
226         },
227 };
228 
229 module_platform_driver(led_pwm_driver);
230 
231 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
232 MODULE_DESCRIPTION("generic PWM LED driver");
233 MODULE_LICENSE("GPL v2");
234 MODULE_ALIAS("platform:leds-pwm");
235 

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