android 系统重启关机 方法 非常好的一篇文章
1.5 android 系統重啟關機流程分析
1.5.1 c語言中調用 reboot 函數 ?HAL層中重啟系統的方法
bionic/libc/unistd/reboot.c:33:
使用需要的頭文件：#include?<sys/reboot.h>?
int reboot (int mode)
{
return __reboot( LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, mode,NULL );
}
1.5.2 通過 adb 讓系統重啟
adb reboot recovery 進入 recovery 模式
adb reboot bootloader 進入 fastboot 模式
adb reboot-bootloader
adb reboot 不帶參數 系統正常重啟
adb 是pc端工具，adbd是服務端，運行在手機
adbd 讀取 socket 解析由 adb 傳過來的命令串
int service_to_fd(const char *name)
if(!strncmp(name, "reboot:", 7)) {
void* arg = strdup(name + 7);
if(arg == 0) return -1;
ret = create_service_thread(reboot_service, arg);
system/core/adb/services.c:176:
void reboot_service(int fd, void *arg)
{
。。。
ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
LINUX_REBOOT_CMD_RESTART2, (char *)arg);
。。。
}
bionic/libc/kernel/common/linux/reboot.h
#define LINUX_REBOOT_CMD_RESTART 0x01234567
#define LINUX_REBOOT_CMD_HALT 0xCDEF0123
kernel/include/linux/reboot.h:33:
#define LINUX_REBOOT_CMD_RESTART2 0xA1B2C3D4
arg 對應字符串： recovery bootloader
./kernel/arch/arm/mach-msm/pm2.c
system/core/adb/commandline.c
if (!strcmp(argv[0], "reboot-bootloader"))
snprintf(command, sizeof(command), "reboot:bootloader");
如果輸入 adb reboot-bootloader adb 會對該命令進行轉換 相當于執行 adb rebootbootloader
1.5.3 fastboot 模式下系統重啟
fastboot reboot 系統正常重啟
fastboot reboot-bootloader 重啟進入fastboot 模式
fastboot 是 appboot 提供的功能，可以用它來燒寫 system 等鏡像文件
bootable/bootloader/lk/app/aboot/aboot.c
APP_START(aboot)
.init = aboot_init,
void aboot_init(const struct app_descriptor *app)
｛
。。。
fastboot_register("reboot", cmd_reboot);
fastboot_register("reboot-bootloader",cmd_reboot_bootloader);
。。。
｝
void cmd_reboot(const char *arg, void *data, unsigned sz)
{
dprintf(INFO, "rebooting the device\n");
fastboot_okay("");
reboot_device(0);
}
void cmd_reboot_bootloader(const char *arg, void *data, unsignedsz)
{
dprintf(INFO, "rebooting the device\n");
fastboot_okay("");
reboot_device(FASTBOOT_MODE);
}
bootable/bootloader/lk/target/msm7630_surf/init.c:311:
void reboot_device(unsigned reboot_reason)
bootable/bootloader/lk/target/msm7627_ffa/init.c:174:
void reboot_device(unsigned reboot_reason)
void reboot_device(unsigned reboot_reason)
{
reboot(reboot_reason);
}
調用的是c函數：
bionic/libc/unistd/reboot.c:33:
int reboot (int mode)
{
return __reboot( LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, mode,NULL );
}
bootable/bootloader/lk/app/aboot/aboot.c:59:
#define FASTBOOT_MODE 0x77665500
if (!strcmp(cmd, "bootloader")) {
restart_reason = 0x77665500;
}
1.5.4 系統關機
正常按鍵關機
./frameworks/policies/base/phone/com/android/internal/policy/impl/PhoneWindowManager.java
void showGlobalActionsDialog()
mGlobalActions.showDialog(keyguardShowing,isDeviceProvisioned());
調用文件：
./frameworks/policies/base/phone/com/android/internal/policy/impl/GlobalActions.java
中的函數：
public void showDialog(boolean keyguardShowing, booleanisDeviceProvisioned)
mDialog = createDialog();
調用本文件中的函數：
private AlertDialog createDialog()
public void onPress() {
ShutdownThread.shutdownAfterDisablingRadio(mContext, true);
}
調用文件：
./frameworks/policies/base/phone/com/android/internal/policy/impl/ShutdownThread.java
中的函數：
public static void shutdownAfterDisablingRadio(final Contextcontext, boolean confirm)
beginShutdownSequence(context)
調用本文件中的函數：
private static void beginShutdownSequence(Context context)
sInstance.start()
進入關機線程的run函數：
public void run() {
首先關藍牙，關射頻，然后再關電源
...
sBluetooth.disable(false)
...
sPhone.setRadio(false)
...
SystemClock.sleep(PHONE_STATE_POLL_SLEEP_MSEC);
...
Power.shutdown()
}
frameworks/base/core/java/android/os/Power.java:92:
public static native void shutdown();
frameworks/base/core/jni/android_os_Power.cpp:107:
{ "shutdown", "()V", (void*)android_os_Power_shutdown },
jni 調用
static void android_os_Power_shutdown(JNIEnv *env, jobjectclazz)
{
sync();
#ifdef HAVE_ANDROID_OS
reboot(RB_POWER_OFF);
#endif
}
因為有 bionic/libc/include/sys/reboot.h:42:
#define RB_POWER_OFF LINUX_REBOOT_CMD_POWER_OFF
所以實際相對執行
reboot(LINUX_REBOOT_CMD_POWER_OFF);
__reboot( LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,LINUX_REBOOT_CMD_POWER_OFF, NULL );
這里的 __reboot 是libc中的系統調用
bionic/libc/arch-x86/syscalls/__reboot.S
#include<sys/linux-syscalls.h>
.text
.type __reboot, #function
.globl __reboot
.align 4
.fnstart
__reboot:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_reboot
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend
1.5.5 內核中的系統調用 reboot
__NR_reboot 執行的是內核中的系統調用：
kernel/kernel/sys.c:310:
SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int,cmd,
void __user *, arg)
{
char buffer[256];
int ret = 0;
if (!capable(CAP_SYS_BOOT))
return -EPERM;
if (magic1 != LINUX_REBOOT_MAGIC1 ||
(magic2 != LINUX_REBOOT_MAGIC2&&
magic2 != LINUX_REBOOT_MAGIC2A&&
magic2 != LINUX_REBOOT_MAGIC2B&&
magic2 != LINUX_REBOOT_MAGIC2C))
return -EINVAL;
if ((cmd == LINUX_REBOOT_CMD_POWER_OFF)&& !pm_power_off)
cmd = LINUX_REBOOT_CMD_HALT;
lock_kernel();
switch (cmd) {
case LINUX_REBOOT_CMD_RESTART:
kernel_restart(NULL);
break;
case LINUX_REBOOT_CMD_CAD_ON:
C_A_D = 1;
break;
case LINUX_REBOOT_CMD_CAD_OFF:
C_A_D = 0;
break;
case LINUX_REBOOT_CMD_HALT:
kernel_halt();
unlock_kernel();
do_exit(0);
panic("cannot halt");
case LINUX_REBOOT_CMD_POWER_OFF:
kernel_power_off();
unlock_kernel();
do_exit(0);
break;
case LINUX_REBOOT_CMD_RESTART2:
if (strncpy_from_user(&buffer[0], arg,sizeof(buffer) - 1) < 0) {
unlock_kernel();
return -EFAULT;
}
buffer[sizeof(buffer) - 1] = '\0';
kernel_restart(buffer);
break;
#ifdef CONFIG_KEXEC
case LINUX_REBOOT_CMD_KEXEC:
ret = kernel_kexec();
break;
#endif
#ifdef CONFIG_HIBERNATION
case LINUX_REBOOT_CMD_SW_SUSPEND:
ret = hibernate();
break;
#endif
default:
ret = -EINVAL;
break;
}
unlock_kernel();
return ret;
}
void kernel_restart(char *cmd)
{
kernel_restart_prepare(cmd);
if (!cmd)
printk(KERN_EMERG "Restarting system.\n");
else
printk(KERN_EMERG "Restarting system with command '%s'.\n",cmd);
machine_restart(cmd);
}
kernel/kernel/sys.c:341:
void kernel_power_off(void)
{
kernel_shutdown_prepare(SYSTEM_POWER_OFF);
if (pm_power_off_prepare)
pm_power_off_prepare();
disable_nonboot_cpus();
sysdev_shutdown();
printk(KERN_EMERG "Power down.\n");
machine_power_off();
}
./kernel/arch/arm/kernel/process.c:219:
void machine_restart(char *cmd)
{
arm_pm_restart(reboot_mode, cmd);
}
void machine_power_off(void)
{
if (pm_power_off)
pm_power_off();
}
因為./kernel/arch/arm/mach-msm/pm2.c:1740:中有：
arm_pm_restart = msm_pm_restart;
pm_power_off = msm_pm_power_off;
所以 arm_pm_restart 調用的是：
static void msm_pm_restart(char str, const char *cmd)
{
msm_rpcrouter_close();
msm_proc_comm(PCOM_RESET_CHIP, &restart_reason,0);
for (;;)
;
}
pm_power_off 調用的是：
static void msm_pm_power_off(void)
{
msm_rpcrouter_close();
msm_proc_comm(PCOM_POWER_DOWN, 0, 0);
for (;;)
;
}
msm_proc_comm 是芯片級別的操作
msm_proc_comm_reset_modem_now 對modem芯片進行重啟
kernel/arch/arm/mach-msm/proc_comm.c:98:
int msm_proc_comm(unsigned cmd, unsigned *data1, unsigned*data2)
{
。。。
writel(cmd, base + APP_COMMAND);
writel(data1 ? *data1 : 0, base + APP_DATA1);
writel(data2 ? *data2 : 0, base + APP_DATA2);
。。。
}
內核里面writel是如何實現的
http://blog.chinaunix.net/u2/77776/showart_1404857.html
補充信息：
static int msm_reboot_call
(struct notifier_block *this, unsigned long code, void*_cmd)
{
if ((code == SYS_RESTART) &&_cmd) {
char *cmd = _cmd;
if (!strcmp(cmd, "bootloader")) {
restart_reason = 0x77665500;
} else if (!strcmp(cmd, "recovery")) {
restart_reason = 0x77665502;
} else if (!strcmp(cmd, "eraseflash")) {
restart_reason = 0x776655EF;
} else if (!strncmp(cmd, "oem-", 4)) {
unsigned code = simple_strtoul(cmd + 4, 0, 16) &0xff;
restart_reason = 0x6f656d00 | code;
} else {
restart_reason = 0x77665501;
}
}
return NOTIFY_DONE;
}
static struct notifier_block msm_reboot_notifier = {
.notifier_call = msm_reboot_call,
};
static int __init msm_pm_init(void)
register_reboot_notifier(&msm_reboot_notifier);
內核編譯相關：
kernel/arch/arm/mach-msm/pm2.c:1701: restart_reason =0x77665500;
kernel/arch/arm/mach-msm/pm.c:696: restart_reason =0x77665500;
kernel/arch/arm/mach-msm/Makefile:84:
ifdef CONFIG_MSM_N_WAY_SMSM
obj-$(CONFIG_PM) += pm2.o
else
obj-$(CONFIG_PM) += pm.o
endif
kernel/arch/arm/configs/msm7630-perf_defconfig:256:CONFIG_MSM_N_WAY_SMSM=y
kernel/arch/arm/configs/msm7627-perf_defconfig:247:CONFIG_MSM_N_WAY_SMSM=y
make -C kernelO=../out/target/product/msm7627_ffa/obj/KERNEL_OBJ ARCH=armCROSS_COMPILE=arm-eabi- msm7627-perf_defconfig
out/target/product/msm7627_ffa/obj/KERNEL_OBJ/.config
CONFIG_MSM_N_WAY_SMSM=y
總結
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