andriod关机amp;重启分析.doc

Andriod关机重启分析 1、jni层 frameworks/base/core/jni/android_os_Power.cpp static void android_os_Power_shutdown(JNIEnv *env, jobject clazz) { sync(); #ifdef HAVE_ANDROID_OS reboot(RB_POWER_OFF); #endif } static void android_os_Power_reboot(JNIEnv *env, jobject clazz, jstring reason) { sync(); #ifdef HAVE_ANDROID_OS if (reason == NULL) { reboot(RB_AUTOBOOT); } else { const char *chars = env-GetStringUTFChars(reason, NULL); __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_RESTART2, (char*) chars); env-ReleaseStringUTFChars(reason, chars); // In case it fails. } jniThrowIOException(env, errno); #endif } static JNINativeMethod method_table[] = { …... { shutdown, ()V, (void*)android_os_Power_shutdown }, { rebootNative, (Ljava/lang/String;)V, (void*)android_os_Power_reboot }, }; 其中，RB_POWER_OFF 及RB_AUTOBOOT 定义bionic/libc/include/sys/reboot.h 中。 #define RB_AUTOBOOT LINUX_REBOOT_CMD_RESTART #define RB_HALT_SYSTEM LINUX_REBOOT_CMD_HALT #define RB_POWER_OFF LINUX_REBOOT_CMD_POWER_OFF …... 2、通过jni层，最后会执行系统调用sys_reboot，即reboot。以imx51平台为例，reboot定义在kernel_imx/kernel/sys.c …... 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_HALT: kernel_halt(); unlock_kernel(); do_exit(0); break; case LINUX_REBOOT_CMD_POWER_OFF: kernel_power_off(); unlock_kernel(); do_exit(0); break; …... 其中，函数指针pm_power_off是与平台相关的指针，以imx51平台为例，其定义于kernel_imx/arch/arm/mach-mx5/mx51_baggage.c中。 static void mxc_power_off(void) { …... /* Set the power gate bits to power down */ pmic_write_reg(REG_POWER_MISC, (PWGT1SPIEN|PWGT2SPIEN), (PWGT1SPIEN|PWGT2SPIEN)); } 另外，在 static void __init mxc_board_init(void) 函数中，有 pm_power_off