android关机充电的奥妙所在（留着以后用）
一、android正常开机流程、关机充电流程
在写这篇文章之前我们先看两个流程：正常开机流程，关机充电系统启动流程
1、正常开机流程，按开机键。
可大致分成三部分
（1）、OS_level：UBOOT、kenrel、init这三步完成系统启动；
（2）、Android_level：这部分完成android部的初始化；
（3）、Home Screen：这部分就是我们看到的launcher部分。
2、关机充电系统启动流程
与前面相比，这个流程只走到init这一部分，就没有往后走了，这部分我们会在后面的代码中分析。
二、关机充电逻辑硬件逻辑
1、插入DC，charger IC从硬件上唤醒系统，相当于长按开机键开机。
下面这部分是charger IC连接系统的控制部分。
三、软件逻辑。
DC插入，其实相当于关机状态下“按开机键”开机。第一步要走UBOOT、kernel 、android init这一流程。
1、UBOOT
UBOOT启动代码我们不在这里详细分析，这里我们只要注意二个问题：
a：如何判断是DC插入；
b：设定setenv("bootargs", "androidboot.mode=charger")，androidboot.mode这个参数相当重要，这个参数决定系统是正常启动、还是关机充电状态。
Uboot/board/samsung/smdk4212/smkd4212.c
- int board_late_init (void)
- {
- int keystate = 0;
- printf("check start mode\n");
- if ((*(int *)0x10020800==0x19721212) || (*(int *)0x10020804==0x19721212)
- || (*(int *)0x10020808==0x19721212))//（1）、检查是否有DC插入；
- {
- setenv ("bootargs", "");//（2）、没有DC插入；
- } else {//DC插入
- int tmp=*(int *)0x11000c08;
- *(int *)0x10020800=*(int *)0x10020804=0x19721212;
- *(int *)0x11000c08=(tmp&(~0xc000))|0xc000;
- udelay(10000);
- if ((*(int *)0x11000c04 & 0x80)!=0x80 && INF_REG4_REG != 0xf) {
- setenv ("bootargs","androidboot.mode=charger");//（3）、设定bootargs为charger状态
- printf("charger mode\n");
- } else {
- setenv ("bootargs", "");
- }
- *(int *)0x11000c08=tmp;
- }
- #ifdef CONFIG_CPU_EXYNOS4X12
- int charge_status=CheckBatteryLow();//（4）、检查电池电量；
- keystate=board_key_check();//（5）、检查按键状态；
- // fuse bootloader
- if(second_boot_info != 0) {
- boot_symbol=1;
- INF_REG2_REG =0x8;
- run_command(CONFIG_BOOTCMD_FUSE_BOOTLOADER, NULL);
- }
- if((INF_REG4_REG == 0xd)) {
- // reboot default
- char buf[10];
- sprintf(buf, "%d", CONFIG_BOOTDELAY);
- setenv ("bootdelay", buf);
- setenv ("reserved", NULL);
- saveenv();
- } else if((INF_REG4_REG == 0xe) || keystate == (0x1 | 0x2)) {//（6）、按键进入fastboot模式；
- // reboot bootloader
- boot_symbol=1;
- INF_REG2_REG =0x8;
- printf("BOOTLOADER - FASTBOOT\n");
- setenv ("reserved","fastboot");
- setenv ("bootdelay", "0");
- } else if((INF_REG4_REG == 0xf) || keystate == (0x1 | 0x2 | 0x4)) {//（7）、按键进入recovery模式；
- // reboot recovery
- printf("BOOTLOADER - RECOVERY\n");
- boot_symbol=1;
- INF_REG2_REG =0x8;
- setenv ("reserved", CONFIG_BOOTCMD_RECOVERY);
- setenv ("bootdelay","0");
- } else
- if(keystate == (0x1 | 0x4) || second_boot_info != 0 || partition_check()) {//（8）、按键进入卡升级模式；
- // 2nd boot
- printf("BOOTLOADER - 2ND BOOT DEVICE\n");
- boot_symbol=1;
- INF_REG2_REG =0x8;
- setenv ("bootcmd", CONFIG_BOOTCOMMAND);
- setenv ("reserved", CONFIG_BOOTCMD_FUSE_RELEASE);
- setenv ("bootdelay", "0");
- } else {//（9）、正常启动；
- // normal case
- char buf[10];
- sprintf(buf, "%d", CONFIG_BOOTDELAY);
- setenv ("bootdelay", buf);
- }
- INF_REG4_REG = 0;
- return 0;
- }
（1）、检查是否有DC插入；
- if ((*(int *)0x10020800==0x19721212) || (*(int *)0x10020804==0x19721212)
- (*(int *)0x10020808==0x19721212))
这部分检查寄存器的值。
（2）、没有DC插入；
（3）、设定bootargs为charger状态
- if ((*(int *)0x11000c04 & 0x80)!=0x80 && INF_REG4_REG != 0xf) {
- setenv ("bootargs", "androidboot.mode=charger");
这是这部分的重点，如果能过寄存器判断是DC插入，把androidboot.mode设定为charger状态。
以下这部分根据需要加入，通过判断不同的情况进入不同的功能，如fastboot\revovery…………，这部分不做详细解释。
（4）、检查电池电量；
这个在正常开机状态下，如果检测电量太低，则不开机，这部分代码就不做分析。
（5）、检查按键状态；
我们这个平台有几种模式:fastboot\recovery\卡升级等……
（6）、按键进入fastboot模式；
（7）、按键进入recovery模式；
（8）、按键进入卡升级模式
（9）、正常启动；
2、kernel
这部分和正常启动是一样的。
3、init
前面所有的描述其实只有一点和正常启动不太一样，那就是在UBOOT中把androidboot.mode设定为charger状态，内核正常流程启动，然后到init时要对charger这种状态处理。
system\core\init\init.c
- int main(int argc,char **argv)
- {
- ………………
- action_for_each_trigger("early-init", action_add_queue_tail);
- queue_builtin_action(wait_for_coldboot_done_action, "wait_for_coldboot_done");
- queue_builtin_action(property_init_action, "property_init");
- queue_builtin_action(keychord_init_action, "keychord_init");
- queue_builtin_action(console_init_action, "console_init"); //(1)、显示initlogo.rle，也就是android第二张图片;
- queue_builtin_action(set_init_properties_action, "set_init_properties");
- /* execute all the boot actions to get us started */
- action_for_each_trigger("init", action_add_queue_tail);
- /* skip mounting filesystems in charger mode */
- if (strcmp(bootmode, "charger") != 0) {//(2)、这里就是UBOOT中设定的bootmode，如果是charger模式，跳过下面初始化；
- action_for_each_trigger("early-fs", action_add_queue_tail);
- action_for_each_trigger("fs", action_add_queue_tail);
- action_for_each_trigger("post-fs", action_add_queue_tail);
- action_for_each_trigger("post-fs-data", action_add_queue_tail);
- }
- queue_builtin_action(property_service_init_action, "property_service_init");
- queue_builtin_action(signal_init_action, "signal_init");
- queue_builtin_action(check_startup_action, "check_startup");
- if (!strcmp(bootmode,"charger")) {//(3)、如果为charger，则调用charger.c。
- action_for_each_trigger("charger", action_add_queue_tail);
- } else {
- action_for_each_trigger("early-boot", action_add_queue_tail);
- action_for_each_trigger("boot", action_add_queue_tail);
- }
- ……………………
- }
(1)、显示initlogo.rle，也就是android第二张图片;
queue_builtin_action(console_init_action,"console_init");调用console_init_action
- static int console_init_action(int nargs,char **args)
- {
- int fd;
- char tmp[PROP_VALUE_MAX];
- if (console[0]) {
- snprintf(tmp, sizeof(tmp), "/dev/%s", console);
- console_name = strdup(tmp);
- }
- fd = open(console_name, O_RDWR);
- if (fd >= 0)
- have_console = 1;
- close(fd);
- if( load_565rle_image(INIT_IMAGE_FILE) ) {//这里定义rle文件的名称#define INIT_IMAGE_FILE "/initlogo.rle"
- fd = open("/dev/tty0", O_WRONLY);
- if (fd >= 0) {//如果没有这张图片，就显示android字样，在屏幕左上角；
- const char *msg;
- msg = "\n"
- "\n"
- "\n" // console is 40 cols x 30 lines
- "\n"
- "\n"
- "\n"
- "\n"
- "\n"
- "\n"
- "\n"
- " A N D R O I D ";
- write(fd, msg, strlen(msg));
- close(fd);
- }
- }
- return 0;
- }
(2)、这里就是UBOOT中设定的bootmode，如果是charger模式，跳过下面初始化；
- /* skip mounting filesystems in charger mode */
- if (strcmp(bootmode, "charger") != 0) {
- action_for_each_trigger("early-fs", action_add_queue_tail);
- action_for_each_trigger("fs", action_add_queue_tail);
- action_for_each_trigger("post-fs", action_add_queue_tail);
- action_for_each_trigger("post-fs-data", action_add_queue_tail);
- }
(3)、如果为charger，则调用charger.c
- action_for_each_trigger("charger", action_add_queue_tail);
我们在后面细分charger这部分。
4、charger.c
这部分就是我们充电部分，充电画面显示的实现。
system\core\charger\charger.c
- int main(int argc,char **argv)
- {
- ………………
- klog_set_level(CHARGER_KLOG_LEVEL);
- dump_last_kmsg();
- LOGI("--------------- STARTING CHARGER MODE ---------------\n");
- gr_init();
- gr_font_size(&char_width, &char_height); //(1)、初始化graphics,包括buf大小；
- ev_init(input_callback, charger);//(2)初始化按键；
- fd = uevent_open_socket(64*1024, true);
- if (fd >= 0) {
- fcntl(fd, F_SETFL, O_NONBLOCK);
- ev_add_fd(fd, uevent_callback, charger);
- }
- charger->uevent_fd = fd;
- coldboot(charger, "/sys/class/power_supply","add");//(3)、创建/sys/class/power_supply结点，把socket信息通知应用层；
- ret = res_create_surface("charger/battery_fail", &charger->surf_unknown);
- if (ret < 0) {
- LOGE("Cannot load image\n");
- charger->surf_unknown = NULL;
- }
- for (i = 0; i < charger->batt_anim->num_frames; i++) {//(4)、这里是显示charger logo，res_create_surface显示图片函数；
- struct frame *frame = &charger->batt_anim->frames[i];
- ret = res_create_surface(frame->name, &frame->surface);
- if (ret < 0) {
- LOGE("Cannot load image %s\n", frame->name);
- /* TODO: free the already allocated surfaces... */
- charger->batt_anim->num_frames = 0;
- charger->batt_anim->num_cycles = 1;
- break;
- }
- }
- ev_sync_key_state(set_key_callback, charger);
- gr_fb_blank(true);
- charger->next_screen_transition = now - 1;
- charger->next_key_check = -1;
- charger->next_pwr_check = -1;
- reset_animation(charger->batt_anim);
- kick_animation(charger->batt_anim);
- event_loop(charger);//（5）、event_loop循环，电池状态，检测按键是否按下；
- return 0;
- }
(1)、初始化graphics,包括buf大小
android/bootable/recovery/minui/graphics.c
gr_init():minui/graphics.c［settty0 to graphic mode, open fb0]，设制tty0为图形模式，打开fb0;
- int gr_init(void)
- {
- gglInit(&gr_context);
- GGLContext *gl = gr_context;
- gr_init_font();
- gr_vt_fd = open("/dev/tty0", O_RDWR | O_SYNC);
- if (gr_vt_fd < 0) {
- // This is non-fatal; post-Cupcake kernels don't have tty0.
- perror("can't open /dev/tty0");
- } else if (ioctl(gr_vt_fd, KDSETMODE, (void*) KD_GRAPHICS)) {
- // However, if we do open tty0, we expect the ioctl to work.
- perror("failed KDSETMODE to KD_GRAPHICS on tty0");
- gr_exit();
- return -1;
- }
- gr_fb_fd = get_framebuffer(gr_framebuffer);
- if (gr_fb_fd < 0) {
- gr_exit();
- return -1;
- }
- get_memory_surface(&gr_mem_surface);
- fprintf(stderr, "framebuffer: fd %d (%d x %d)\n",
- gr_fb_fd, gr_framebuffer[0].width, gr_framebuffer[0].height);
- /* start with 0 as front (displayed) and 1 as back (drawing) */
- gr_active_fb = 0;
- set_active_framebuffer(0);
- gl->colorBuffer(gl, &gr_mem_surface);
- gl->activeTexture(gl, 0);
- gl->enable(gl, GGL_BLEND);
- gl->blendFunc(gl, GGL_SRC_ALPHA, GGL_ONE_MINUS_SRC_ALPHA);
- gr_fb_blank(true);
- gr_fb_blank(false);
- return 0;
- }
(2)android/bootable/recovery/minui/events.c
ev_init():minui/events.c[open /dev/input/event*]打开 /dev/input/event*
这部分是在，充电状态下，按键操作的初始化，比如：短按显示充电logo，长按开机，初始化代码如下。
- int ev_init(ev_callback input_cb,void *data)
- {
- DIR *dir;
- struct dirent *de;
- int fd;
- dir = opendir("/dev/input");//打开驱动结点；
- if(dir != 0) {
- while((de = readdir(dir))) {
- unsigned long ev_bits[BITS_TO_LONGS(EV_MAX)];
- // fprintf(stderr,"/dev/input/%s\n", de->d_name);
- if(strncmp(de->d_name,"event",5))continue;
- fd = openat(dirfd(dir), de->d_name, O_RDONLY);
- if(fd < 0) continue;
- /* read the evbits of the input device */
- if (ioctl(fd, EVIOCGBIT(0,sizeof(ev_bits)), ev_bits) < 0) {
- close(fd);
- continue;
- }
- /* TODO: add ability to specify event masks. For now, just assume
- * that only EV_KEY and EV_REL event types are ever needed. */
- if (!test_bit(EV_KEY, ev_bits) && !test_bit(EV_REL, ev_bits)) {
- close(fd);
- continue;
- }
- ev_fds[ev_count].fd = fd;
- ev_fds[ev_count].events = POLLIN;
- ev_fdinfo[ev_count].cb = input_cb;
- ev_fdinfo[ev_count].data = data;
- ev_count++;
- ev_dev_count++;
- if(ev_dev_count == MAX_DEVICES)break;
- }
- }
- return 0;
- }
(3)、创建/sys/class/power_supply结点，把socket信息通知应用层
uevent_open_socket这个函数是通过kobject_uevent的方式通知的应用层，就是往一个socket广播一个消息，只需要在应用层打开socket监听NETLINK_KOBJECT_UEVENT组的消息，就可以收到了,主要是创建了socket接口获得uevent的文件描述符，然后触发/sys/class/power_supply目录及其子目录下的uevent，然后接受并创建设备节点，至此设备节点才算创建。
(4)、这里显示charger logo，res_create_surface显示图片函数；
res_create_surface:minui/resource.c[create surfaces for all bitmaps used later, include icons, bmps]
创建surface为所以的位图，包括图标、位图。 这些图片的位置为：system\core\charger\images
（5）、event_loop循环，电池状态，检测按键是否按下；
5、event_loop
这个函数判断按键状态，DC是否插拔。如果长按开机：执行android_reboot(ANDROID_RB_RESTART,0, 0);如果拔出DC:执行android_reboot(ANDROID_RB_POWEROFF,0, 0);
- static void event_loop(struct charger *charger)
- {
- int ret;
- while (true) {
- int64_t now = curr_time_ms();//（1）、获得当前时间；
- LOGV("[%lld] event_loop()\n", now);
- handle_input_state(charger, now);//（2）、检查按键状态；
- handle_power_supply_state(charger, now);// (3)、检查DC是否拔出；
- /* do screen update last in case any of the above want to start
- * screen transitions (animations, etc)
- */
- update_screen_state(charger, now);//(4)、对按键时间状态标志位的判断，显示不同电量的充电logo;
- wait_next_event(charger, now);
- }
- }
（1）、获得当前时间；
int64_t now = curr_time_ms();
这个时间来判断，有没有屏幕超时，如果超时关闭屏幕充电logo显示。
（2）、检查按键状态；
- static void handle_input_state(struct charger *charger, int64_t now)
- {
- process_key(charger, KEY_POWER, now);
- if (charger->next_key_check != -1 && now > charger->next_key_check)
- charger->next_key_check = -1;
- }
- 我们再看下：process_key(charger, KEY_POWER, now);
- static void process_key(struct charger *charger,int code, int64_t now)
- {
- ………………
- if (code == KEY_POWER) {
- if (key->down) {
- int64_t reboot_timeout = key->timestamp + POWER_ON_KEY_TIME;
- if (now >= reboot_timeout) {//如果长按power键，就重新启动，也就是重启开机；
- LOGI("[%lld] rebooting\n", now);
- android_reboot(ANDROID_RB_RESTART, 0, 0);//重启命令；
- }
- ………………
- }
- key->pending = false;
- }
（3）、检查DC是否拔出；
handle_power_supply_state(charger, now);
- static void handle_power_supply_state(struct charger *charger, int64_t now)
- {
- if (charger->num_supplies_online == 0) {
- if (charger->next_pwr_check == -1) {
- charger->next_pwr_check = now + UNPLUGGED_SHUTDOWN_TIME;
- LOGI("[%lld] device unplugged: shutting down in %lld (@ %lld)\n",
- now, UNPLUGGED_SHUTDOWN_TIME, charger->next_pwr_check);
- } else if (now >= charger->next_pwr_check) {
- LOGI("[%lld] shutting down\n", now);
- android_reboot(ANDROID_RB_POWEROFF, 0, 0);//如果DC拔出，则关机；
- }
- ………………
- }
(4)、对按键时间状态标志位的判断，显示不同电量的充电logo;
update_screen_state(charger, now);
这个函数比较长了，其实做用就是：我们在状态的过程中,充电logo的电量是要增加的，比如电量是20%时，要从第一格开始闪烁；如果是80%时，则要从第三格开始闪烁，电量显示就是通过这个函数来计算实现的。
- static void update_screen_state(struct charger *charger, int64_t now)
- {
- struct animation *batt_anim = charger->batt_anim;
- int cur_frame;
- int disp_time;
- if (!batt_anim->run || now < charger->next_screen_transition)
- return;
- /* animation is over, blank screen and leave */
- if (batt_anim->cur_cycle == batt_anim->num_cycles) {
- reset_animation(batt_anim);
- charger->next_screen_transition = -1;
- gr_fb_blank(true);
- LOGV("[%lld] animation done\n", now);
- return;
- }
- disp_time = batt_anim->frames[batt_anim->cur_frame].disp_time;
- /* animation starting, set up the animation */
- if (batt_anim->cur_frame == 0) {
- int batt_cap;
- int ret;
- LOGV("[%lld] animation starting\n", now);
- batt_cap = get_battery_capacity(charger);
- if (batt_cap >= 0 && batt_anim->num_frames != 0) {
- int i;
- /* find first frame given current capacity */
- for (i = 1; i < batt_anim->num_frames; i++) {
- if (batt_cap < batt_anim->frames[i].min_capacity)
- break;
- }
- batt_anim->cur_frame = i - 1;
- /* show the first frame for twice as long */
- disp_time = batt_anim->frames[batt_anim->cur_frame].disp_time * 2;
- }
- batt_anim->capacity = batt_cap;
- }
- /* unblank the screen on first cycle */
- if (batt_anim->cur_cycle == 0)
- gr_fb_blank(false);
- /* draw the new frame (@ cur_frame) */
- redraw_screen(charger);
- /* if we don't have anim frames, we only have one image, so just bump
- * the cycle counter and exit
- */
- if (batt_anim->num_frames == 0 || batt_anim->capacity < 0) {
- LOGV("[%lld] animation missing or unknown battery status\n", now);
- charger->next_screen_transition = now + BATTERY_UNKNOWN_TIME;
- batt_anim->cur_cycle++;
- return;
- }
- /* schedule next screen transition */
- charger->next_screen_transition = now + disp_time;
- /* advance frame cntr to the next valid frame
- * if necessary, advance cycle cntr, and reset frame cntr
- */
- batt_anim->cur_frame++;
- /* if the frame is used for level-only, that is only show it when it's
- * the current level, skip it during the animation.
- */
- while (batt_anim->cur_frame < batt_anim->num_frames &&
- batt_anim->frames[batt_anim->cur_frame].level_only)
- batt_anim->cur_frame++;
- if (batt_anim->cur_frame >= batt_anim->num_frames) {
- batt_anim->cur_cycle++;
- batt_anim->cur_frame = 0;
- /* don't reset the cycle counter, since we use that as a signal
- * in a test above to check if animation is over
- */
- }
- }
下面是不能容量时显示logo的函数：
- static struct frame batt_anim_frames[] = {
- {
- .name = "charger/battery_0",
- .disp_time = 750,
- .min_capacity = 0,
- },
- {
- .name = "charger/battery_1",
- .disp_time = 750,
- .min_capacity = 20,
- },
- {
- .name = "charger/battery_2",
- .disp_time = 750,
- .min_capacity = 40,
- },
- {
- .name = "charger/battery_3",
- .disp_time = 750,
- .min_capacity = 60,
- },
- {
- .name = "charger/battery_4",
- .disp_time = 750,
- .min_capacity = 80,
- .level_only = true,
- },
- {
- .name = "charger/battery_5",
- .disp_time = 750,
- .min_capacity = BATTERY_FULL_THRESH,
- },
- };