Android 呼吸灯流程分析

一、Android呼吸灯Driver实现

      1、注册驱动

      代码位置：mediatek/kernel/drivers/leds/leds_drv.c

602static struct platform_driver mt65xx_leds_driver = {
603 .driver     = {
604     .name   = "leds-mt65xx",
605     .owner  = THIS_MODULE,
606 },
607 .probe      = mt65xx_leds_probe,
608 .remove     = mt65xx_leds_remove,
609 //.suspend  = mt65xx_leds_suspend,
610 .shutdown   = mt65xx_leds_shutdown,
611};

       2、闪烁控制

       在probe函数中，对于呼吸灯的闪烁，重点是函数：

466     g_leds_data[i]->cdev.brightness_set = mt65xx_led_set;
467     g_leds_data[i]->cdev.blink_set = mt65xx_blink_set;    //控制呼吸灯闪烁
468
469     INIT_WORK(&g_leds_data[i]->work, mt_mt65xx_led_work);
470
471     ret = led_classdev_register(&pdev->dev, &g_leds_data[i]->cdev); //注册相关设备文件
472

      函数：mt65xx_blink_set主要是通过如下流程来控制呼吸灯闪烁：
                  mt65xx_blink_set ----> mt_mt65xx_blink_set -----> mt_led_blink_pmic
 

268#define PMIC_PERIOD_NUM (sizeof(pmic_freqsel_array)/sizeof(pmic_freqsel_array[0]))
269// 100 * period, ex: 0.01 Hz -> 0.01 * 100 = 1
270int pmic_period_array[] = {250,500,1000,1250,1666,2000,2500,10000};
271//int pmic_freqsel_array[] = {99999, 9999, 4999, 1999, 999, 499, 199, 4, 0};
272int pmic_freqsel_array[] = {0, 4, 199, 499, 999, 1999, 1999, 1999};

274static int find_time_index_pmic(int time_ms) {
275 int i;
276 for(i=0;i<PMIC_PERIOD_NUM;i++) {
277     if(time_ms<=pmic_period_array[i]) {
278         return i;
279     } else {
280         continue;
281     }
282 }
283 return PMIC_PERIOD_NUM-1;
284}

286int mt_led_blink_pmic(enum mt65xx_led_pmic pmic_type, struct nled_setting* led) {
287 int time_index = 0;
288 int duty = 0;
289 LEDS_DEBUG("[LED]led_blink_pmic: pmic_type=%d
", pmic_type);
290
291 if((pmic_type != MT65XX_LED_PMIC_NLED_ISINK0 && pmic_type!= MT65XX_LED_PMIC_NLED_ISINK1 &&
292     pmic_type!= MT65XX_LED_PMIC_NLED_ISINK2 && pmic_type!= MT65XX_LED_PMIC_NLED_ISINK3) || led->nled_mode != NLED_BLINK) {
293     return -1;
294 }
295
296 LEDS_DEBUG("[LED]LED blink on time = %d offtime = %d
",led->blink_on_time,led->blink_off_time);
297 time_index = find_time_index_pmic(led->blink_on_time + led->blink_off_time);
298 LEDS_DEBUG("[LED]LED index is %d  freqsel=%d
", time_index, pmic_freqsel_array[time_index]);
299 duty=32*led->blink_on_time/(led->blink_on_time + led->blink_off_time);
300 //upmu_set_rg_drv_2m_ck_pdn(0x0); // Disable power down (Indicator no need)
301     upmu_set_rg_drv_32k_ck_pdn(0x0); // Disable power down
302 switch(pmic_type){
303     case MT65XX_LED_PMIC_NLED_ISINK0:
304         upmu_set_rg_isink0_ck_pdn(0);
305         upmu_set_rg_isink0_ck_sel(0);
306         upmu_set_isink_ch0_mode(PMIC_PWM_0);
307         upmu_set_isink_ch0_step(0x0);//4mA
308         upmu_set_isink_dim0_duty(duty);
309         upmu_set_isink_dim0_fsel(pmic_freqsel_array[time_index]);
310         upmu_set_isink_breath0_trf_sel(0x0);
311         upmu_set_isink_breath0_ton_sel(0x02);
312         upmu_set_isink_breath0_toff_sel(0x05);
313         upmu_set_isink_ch0_en(0x01);
314         break;
315     case MT65XX_LED_PMIC_NLED_ISINK1:
316         upmu_set_rg_isink1_ck_pdn(0);
317         upmu_set_rg_isink1_ck_sel(0);
318         upmu_set_isink_ch1_mode(PMIC_PWM_0);
319         upmu_set_isink_ch1_step(0x0);//4mA
320         upmu_set_isink_dim1_duty(duty);
321         upmu_set_isink_dim1_fsel(pmic_freqsel_array[time_index]);
322         upmu_set_isink_breath1_trf_sel(0x0);
323         upmu_set_isink_breath1_ton_sel(0x02);
324         upmu_set_isink_breath1_toff_sel(0x05);
325         upmu_set_isink_ch1_en(0x01);
326         break;
327     case MT65XX_LED_PMIC_NLED_ISINK2:
328         upmu_set_rg_isink2_ck_pdn(0);
329         upmu_set_rg_isink2_ck_sel(0);
330         upmu_set_isink_ch2_mode(PMIC_PWM_0);
331         upmu_set_isink_ch2_step(0x0);//4mA
332         upmu_set_isink_dim2_duty(duty);
333         upmu_set_isink_dim2_fsel(pmic_freqsel_array[time_index]);
334         upmu_set_isink_breath2_trf_sel(0x0);
335         upmu_set_isink_breath2_ton_sel(0x02);
336         upmu_set_isink_breath2_toff_sel(0x05);
337         upmu_set_isink_ch2_en(0x01);
338         break;
339     case MT65XX_LED_PMIC_NLED_ISINK3:
340         upmu_set_rg_isink3_ck_pdn(0);
341         upmu_set_rg_isink3_ck_sel(0);
342         upmu_set_isink_ch3_mode(PMIC_PWM_0);
343         upmu_set_isink_ch3_step(0x3);//16mA
344         upmu_set_isink_dim3_duty(duty);
345         upmu_set_isink_dim3_fsel(pmic_freqsel_array[time_index]);
346         upmu_set_isink_breath3_trf_sel(0x0);
347         upmu_set_isink_breath3_ton_sel(0x02);
348         upmu_set_isink_breath3_toff_sel(0x05);
349         upmu_set_isink_ch3_en(0x01);
350         break;
351     default:
352     break;
353 }
354 return 0;
355}

      相关流程为：led->blink_on_time 和 led->blink_off_time 是我们传下来的呼吸灯的Led_on 和 Led_off的值。
      通过find_time_index_pmic函数计算呼吸灯的频率：假设我们传下来的的值为Led_on=350,Led_off=300 ,则Led_on+Led_off = 650， 650<1000,所find_time_index_pmic返回i=2；对应在数组int pmic_freqsel_array[]中为199.所以呼吸灯的闪烁频率就是 1000/199 = 5HZ。

     3、设备文件注册

      对应函数为：
     ret = led_classdev_register(&pdev->dev, &g_leds_data[i]->cdev); //注册相关设备文件
    代码位置：kernel/drivers/leds/led-class.c

160int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
161{
162 led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
163                   "%s", led_cdev->name);
164 if (IS_ERR(led_cdev->dev))
165     return PTR_ERR(led_cdev->dev);
166
167#ifdef CONFIG_LEDS_TRIGGERS
168 init_rwsem(&led_cdev->trigger_lock);
169#endif
170 /* add to the list of leds */
171 down_write(&leds_list_lock);
172 list_add_tail(&led_cdev->node, &leds_list);
173 up_write(&leds_list_lock);
174
175 if (!led_cdev->max_brightness)
176     led_cdev->max_brightness = LED_FULL;
177
178 led_update_brightness(led_cdev);
179
180 init_timer(&led_cdev->blink_timer);
181 led_cdev->blink_timer.function = led_timer_function;
182 led_cdev->blink_timer.data = (unsigned long)led_cdev;
183
184#ifdef CONFIG_LEDS_TRIGGERS
185 led_trigger_set_default(led_cdev);
186#endif
187
188 printk(KERN_DEBUG "Registered led device: %s
",
189         led_cdev->name);
190
191 return 0;
192}

      注册的设备文件关联在leds_class中：    

228 leds_class->dev_attrs = led_class_attrs;

73
74 static struct device_attribute led_class_attrs[] = {
75  __ATTR(brightness, 0644, led_brightness_show, led_brightness_store),
76  __ATTR(max_brightness, 0444, led_max_brightness_show, NULL),
77 #ifdef CONFIG_LEDS_TRIGGERS
78  __ATTR(trigger, 0644, led_trigger_show, led_trigger_store),
79 #endif
80  __ATTR_NULL,
81};

      然后通过：init_timer(&led_cdev->blink_timer);注册了软件控制呼吸灯闪烁的办法。
      控制呼吸灯闪烁的办法；而是mt65xx_blink_set。
      在上层调用mt65xx_blink_set函数来控制呼吸灯闪烁，主要是通过trigger触发器接口的办法实现的。
    

     4、trigger触发器

    看上面AndroidHAL层控制呼吸灯闪烁的流程中，最后是打开了设备文件：/sys/class/leds/red/trigger

94 char const*const RED_TRIGGER_FILE
95        = "/sys/class/leds/red/trigger";

253 write_str(RED_TRIGGER_FILE, "timer");

    很显然我们驱动中对应的响应函数为：led_trigger_store，往该函数传入的参数为："timer"
    代码位置：kernel/drivers/leds/led-triggers.c

34ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
35      const char *buf, size_t count)
36{
37  struct led_classdev *led_cdev = dev_get_drvdata(dev);
38  char trigger_name[TRIG_NAME_MAX];
39  struct led_trigger *trig;
40  size_t len;
41
42  trigger_name[sizeof(trigger_name) - 1] = '';
43  strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
44  len = strlen(trigger_name);
45
46  if (len && trigger_name[len - 1] == '
')
47      trigger_name[len - 1] = '';
48
49  if (!strcmp(trigger_name, "none")) {
50      led_trigger_remove(led_cdev);
51      return count;
52  }
53
54  down_read(&triggers_list_lock);
55  list_for_each_entry(trig, &trigger_list, next_trig) {
56      if (!strcmp(trigger_name, trig->name)) {
57          down_write(&led_cdev->trigger_lock);
58          led_trigger_set(led_cdev, trig);
59          up_write(&led_cdev->trigger_lock);
60
61          up_read(&triggers_list_lock);
62          return count;
63      }
64  }
65  up_read(&triggers_list_lock);
66
67  return -EINVAL;
68}

        如果触发器名字trigger_name是none的话，就移除掉该触发器，不是的话，就遍历trigger_list,比较trigger_name是“timer”的单元。找到了该单元之后，通过
       led_trigger_set(led_cdev, trig);更新它。
       led_trigger_set首先清除掉旧的name="timer"的触发器，然后用新的name="timer"触发器代替它，最后调用该触发器的trigger->activate(led_cdev)函数。
       在开机时候，系统会自动创建一个trigger_name为“timer”的触发器。代码如下：
               kernel/drivers/leds/ledtrig-timer.c

119 static struct led_trigger timer_led_trigger = {
120 .name     = "timer",
121 .activate = timer_trig_activate,
122 .deactivate = timer_trig_deactivate,
123};
124
125 static int __init timer_trig_init(void)
126 {
127 return led_trigger_register(&timer_led_trigger);
128 }
129
130 static void __exit timer_trig_exit(void)
131 {
132 led_trigger_unregister(&timer_led_trigger);
133 }

        在timer_trig_activate中创建了两个设备文件delay_on和delay_off。
        所以我们总结出来：在HAl层中，函数write_str(RED_TRIGGER_FILE, "timer");的作用就是更新trigger_name=“timer”的触发器，然后调用该触发器的activate函数，创建设备文件：delay_on和delay_off;

         5、呼吸灯闪烁的实现

      在HAL层中，闪烁的时候，做了如下处理：

253     write_str(RED_TRIGGER_FILE, "timer");
254     while (((access(RED_DELAY_OFF_FILE, F_OK) == -1) || (access(RED_DELAY_OFF_FILE, R_OK|W_OK) == -1)) && i<10) {
255         ALOGD("RED_DELAY_OFF_FILE doesn't exist or cannot write!!
");
256         led_wait_delay(5);//sleep 5ms for wait kernel LED class create led delay_off/delay_on node of fs
257         i++;
258     }
259     write_int(RED_DELAY_OFF_FILE, offMS);
260     write_int(RED_DELAY_ON_FILE, onMS);

        从刚才分析我们知道：以上代码会首先更新timer的触发器，然后等待5ms，创建delay_on和delay_off的设备文件，最后往该设备文件中分别写入offMs和onMs.很显然，最后我们要找的就是delay_on和delay_off对应的处理函数函数。

59static ssize_t led_delay_off_store(struct device *dev,
60      struct device_attribute *attr, const char *buf, size_t size)
61{
62  struct led_classdev *led_cdev = dev_get_drvdata(dev);
63  int ret = -EINVAL;
64  char *after;
65  unsigned long state = simple_strtoul(buf, &after, 10);
66  size_t count = after - buf;
67
68  if (isspace(*after))
69      count++;
70
71  if (count == size) {
72      led_blink_set(led_cdev, &led_cdev->blink_delay_on, &state);
73      led_cdev->blink_delay_off = state;
74      ret = count;
75  }
76
77  return ret;
78}

        HAL层中首先写入的是delay_off的时间，对应处理函数如上，之后进入了函数led_blink_set中：

71void led_blink_set(struct led_classdev *led_cdev,
72         unsigned long *delay_on,
73         unsigned long *delay_off)
74{
75  del_timer_sync(&led_cdev->blink_timer);
76
77  if (led_cdev->blink_set &&
78      !led_cdev->blink_set(led_cdev, delay_on, delay_off))
79      return;
80
81  /* blink with 1 Hz as default if nothing specified */
82  if (!*delay_on && !*delay_off)
83      *delay_on = *delay_off = 500;
84
85  led_set_software_blink(led_cdev, *delay_on, *delay_off);
86}
87EXPORT_SYMBOL(led_blink_set);

       该函数首先删除掉软件方法闪烁的定时器，然后调用了led_cdev->blink_set，在blink_set函数中，因为delay_on为0，而delay_off为300,所以会返回-1，从而进入函数led_set_software_blink。

35static void led_set_software_blink(struct led_classdev *led_cdev,
36                 unsigned long delay_on,
37                 unsigned long delay_off)
38{
39  int current_brightness;
40
41  current_brightness = led_get_brightness(led_cdev);
42  if (current_brightness)
43      led_cdev->blink_brightness = current_brightness;
44  if (!led_cdev->blink_brightness)
45      led_cdev->blink_brightness = led_cdev->max_brightness;
46
47  if (led_get_trigger_data(led_cdev) &&
48      delay_on == led_cdev->blink_delay_on &&
49      delay_off == led_cdev->blink_delay_off)
50      return;
51
52  led_stop_software_blink(led_cdev);
53
54  led_cdev->blink_delay_on = delay_on;
55  led_cdev->blink_delay_off = delay_off;
56
57  /* never on - don't blink */
58  if (!delay_on)
59      return;
60
61  /* never off - just set to brightness */
62  if (!delay_off) {
63      led_set_brightness(led_cdev, led_cdev->blink_brightness);
64      return;
65  }
66
67  mod_timer(&led_cdev->blink_timer, jiffies + 1);
68}

         在该函数中更新了led_cdev->blink_delay_off为我们传入的delay_off,也就是300，然后又因为delay_on为0,所以中途退出，不会启动最后的呼吸灯闪烁的软件控制定时器。之后，HAL继续write_int(RED_DELAY_ON_FILE, onMS);往delay_off接口中写入了onMS,也就是上面的350.类似的：

30static ssize_t led_delay_on_store(struct device *dev,
31      struct device_attribute *attr, const char *buf, size_t size)
32{
33  struct led_classdev *led_cdev = dev_get_drvdata(dev);
34  int ret = -EINVAL;
35  char *after;
36  unsigned long state = simple_strtoul(buf, &after, 10);
37  size_t count = after - buf;
38
39  if (isspace(*after))
40      count++;
41
42  if (count == size) {
43      led_blink_set(led_cdev, &state, &led_cdev->blink_delay_off);
44      led_cdev->blink_delay_on = state;
45      ret = count;
46  }
47
48  return ret;
49}

         该函数最后调用了led_blink_set，传入了onMs（350）和上一步保存的offMs（300）。
继续进入
      led_blink_set ---->led_cdev->blink_set  ---> mt65xx_blink_set  --->   mt65xx_blink_set -->  mt_mt65xx_blink_set --->  mt_led_blink_pmic
也就是上面分析的第一种让呼吸灯闪烁的函数：mt_led_blink_pmic。
好了，呼吸灯闪烁，基本就是这样。。。