Re: [PATCH] arm64: support reboot and power off via EFI runtime

From: Mark Rutland
Date: Wed Jun 18 2014 - 09:27:07 EST


Hi Mark,

On Tue, Jun 17, 2014 at 05:45:14PM +0100, Mark Salter wrote:
> Add handlers for arm_pm_resestart and pm_power_off which use EFI
> runtime services ResetSystem call to perform the functions. These
> handlers are only installed if no handler currently exists. This
> allows PSCI to take priority over EFI for these functions.
>
> Signed-off-by: Mark Salter <msalter@xxxxxxxxxx>
> ---
> arch/arm64/kernel/efi.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
> index 14db1f6..e8c0476 100644
> --- a/arch/arm64/kernel/efi.c
> +++ b/arch/arm64/kernel/efi.c
> @@ -19,11 +19,14 @@
> #include <linux/of_fdt.h>
> #include <linux/sched.h>
> #include <linux/slab.h>
> +#include <linux/reboot.h>
> +#include <linux/pm.h>
>
> #include <asm/cacheflush.h>
> #include <asm/efi.h>
> #include <asm/tlbflush.h>
> #include <asm/mmu_context.h>
> +#include <asm/system_misc.h>
>
> struct efi_memory_map memmap;
>
> @@ -467,3 +470,40 @@ static int __init arm64_enter_virtual_mode(void)
> return 0;
> }
> early_initcall(arm64_enter_virtual_mode);
> +
> +static void efi_restart(enum reboot_mode reboot_mode, const char *cmd)
> +{
> + int efi_mode;
> +
> + switch (reboot_mode) {
> + case REBOOT_WARM:
> + case REBOOT_SOFT:
> + efi_mode = EFI_RESET_WARM;
> + break;
> + default:
> + efi_mode = EFI_RESET_COLD;
> + break;
> + }
> + efi.reset_system(efi_mode, 0, 0, NULL);
> +}
> +
> +static void efi_power_off(void)
> +{
> + efi.reset_system(EFI_RESET_SHUTDOWN, 0, 0, NULL);
> +}
> +
> +static int __init setup_efi_reset(void)
> +{
> + if (efi_enabled(EFI_RUNTIME_SERVICES)) {
> + /*
> + * If something (psci, etc) hasn't already registered
> + * a handler, use EFI.
> + */
> + if (arm_pm_restart == NULL)
> + arm_pm_restart = efi_restart;
> + if (pm_power_off == NULL)
> + pm_power_off = efi_power_off;
> + }
> + return 0;
> +}
> +pure_initcall(setup_efi_reset);

This doesn't seem to match the definition of a pure initcall, given that
it depends on the state of EFI runtime services and
arm_{pm_restart,power_off}.

Is there any reason this needs to run so early? Can this not be
called later, when we have more of a guarantee of other reboot /
shutdown mechanisms having been registered?

Cheers,
Mark.
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