Android 呼吸灯流程分析（二）
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\n", 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\n",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\n", 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\n",
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] = '\0';
43 strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
44 len = strlen(trigger_name);
45
46 if (len && trigger_name[len - 1] == '\n')
47 trigger_name[len - 1] = '\0';
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!!\n");
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。。。