/*
* Restart requires that the secondary CPUs stop performing any activity
* while the primary CPU resets the system. Systems with multiple CPUs must
* provide a HW restart implementation, to ensure that all CPUs reset at once.
* This is required so that any code running after reset on the primary CPU
* doesn't have to co-ordinate with other CPUs to ensure they aren't still
* executing pre-reset code, and using RAM that the primary CPU's code wishes
* to use. Implementing such co-ordination would be essentially impossible.
*/
void machine_restart(char *cmd)
{
/* Disable interrupts first */
local_irq_disable();
smp_send_stop();
/*
* UpdateCapsule() depends on the system being reset via
* ResetSystem().
*/
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_reboot(reboot_mode, NULL);
/* Now call the architecture specific reboot code. */
if (arm_pm_restart)
arm_pm_restart(reboot_mode, cmd);
else
do_kernel_restart(cmd);
/*
* Whoops - the architecture was unable to reboot.
*/
printk("Reboot failed -- System halted\n");
while (1);
}
/*
* To the best of our knowledge Windows compatible x86 hardware expects
* the following on reboot:
*
* 1) If the FADT has the ACPI reboot register flag set, try it
* 2) If still alive, write to the keyboard controller
* 3) If still alive, write to the ACPI reboot register again
* 4) If still alive, write to the keyboard controller again
* 5) If still alive, call the EFI runtime service to reboot
* 6) If no EFI runtime service, call the BIOS to do a reboot
*
* We default to following the same pattern. We also have
* two other reboot methods: 'triple fault' and 'PCI', which
* can be triggered via the reboot= kernel boot option or
* via quirks.
*
* This means that this function can never return, it can misbehave
* by not rebooting properly and hanging.
*/
static void native_machine_emergency_restart(void)
{
int i;
int attempt = 0;
int orig_reboot_type = reboot_type;
unsigned short mode;
if (reboot_emergency)
emergency_vmx_disable_all();
tboot_shutdown(TB_SHUTDOWN_REBOOT);
/* Tell the BIOS if we want cold or warm reboot */
mode = reboot_mode == REBOOT_WARM ? 0x1234 : 0;
*((unsigned short *)__va(0x472)) = mode;
/*
* If an EFI capsule has been registered with the firmware then
* override the reboot= parameter.
*/
if (efi_capsule_pending(NULL)) {
pr_info("EFI capsule is pending, forcing EFI reboot.\n");
reboot_type = BOOT_EFI;
}
for (;;) {
/* Could also try the reset bit in the Hammer NB */
switch (reboot_type) {
case BOOT_ACPI:
acpi_reboot();
reboot_type = BOOT_KBD;
break;
case BOOT_KBD:
mach_reboot_fixups(); /* For board specific fixups */
for (i = 0; i < 10; i++) {
kb_wait();
udelay(50);
outb(0xfe, 0x64); /* Pulse reset low */
udelay(50);
}
if (attempt == 0 && orig_reboot_type == BOOT_ACPI) {
attempt = 1;
reboot_type = BOOT_ACPI;
} else {
reboot_type = BOOT_EFI;
}
break;
case BOOT_EFI:
efi_reboot(reboot_mode, NULL);
reboot_type = BOOT_BIOS;
break;
case BOOT_BIOS:
machine_real_restart(MRR_BIOS);
/* We're probably dead after this, but... */
reboot_type = BOOT_CF9_SAFE;
break;
case BOOT_CF9_FORCE:
port_cf9_safe = true;
/* Fall through */
case BOOT_CF9_SAFE:
if (port_cf9_safe) {
u8 reboot_code = reboot_mode == REBOOT_WARM ? 0x06 : 0x0E;
u8 cf9 = inb(0xcf9) & ~reboot_code;
outb(cf9|2, 0xcf9); /* Request hard reset */
udelay(50);
/* Actually do the reset */
outb(cf9|reboot_code, 0xcf9);
udelay(50);
}
reboot_type = BOOT_TRIPLE;
break;
case BOOT_TRIPLE:
load_idt(&no_idt);
__asm__ __volatile__("int3");
/* We're probably dead after this, but... */
reboot_type = BOOT_KBD;
break;
}
}
}
