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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 #include <linux/workqueue.h>
 26 
 27 struct 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 
 37 struct led_pwm_priv {
 38         int num_leds;
 39         struct led_pwm_data leds[0];
 40 };
 41 
 42 static 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 
 54 static 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 
 62 static 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 
 84 static 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 
 90 static 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 
 99 static 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 
143 static 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 
171 static 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 
212 static 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 
221 static const struct of_device_id of_pwm_leds_match[] = {
222         { .compatible = "pwm-leds", },
223         {},
224 };
225 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
226 
227 static 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 
236 module_platform_driver(led_pwm_driver);
237 
238 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
239 MODULE_DESCRIPTION("PWM LED driver for PXA");
240 MODULE_LICENSE("GPL");
241 MODULE_ALIAS("platform:leds-pwm");
242 

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