[U-Boot] [PATCH v3 1/2] x86: Add efi runtime reset

[Heinrich Schuchardt]

On 1/30/19 11:46 AM, Alexander Graf wrote:
> Our selftest will soon test the actual runtime reset function rather than
> the boot time one. For this, we need to ensure that the runtime version
> actually succeeds on x86 to keep our travis tests work.
> 
> So this patch implements an x86 runtime reset function. It is missing
> shutdown functionality today, but OSs usually implement that via ACPI
> and this function does more than the stub from before, so it's at least
> an improvement.
> 
> Eventually we will want to have full DM functionality in runtime services.
> But this fixes a travis failure and doesn't clutter the code too heavily, so
> we should pull it in without the amazing new RTS DM framework.
> 
> Signed-off-by: Alexander Graf <agraf at suse.de>
> 
> ---
> 
> v2 -> v3:
> 
>   - support EFI_RESET_PLATFORM_SPECIFIC
>   - reuse existing x86_sysreset_request() function

The v2->v3 update does not answer the question if the reset is correctly
implemented. We would not want to call a function we do not trust.

@Simon, Bin:
x86_sysreset_request() loosely resembles BOOT_CF9_SAFE in
native_machine_emergency_restart() in Linux arch/x86/kernel/reboot.c
which is tried before using the keyboard controller as last resort.

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);

So the Kernel first switches bit 2 off and bit 1 on, waits, and then
switches bit 2 on, cf.
http://smackerelofopinion.blogspot.com/2011/02/resetting-pc-using-reset-control.html

Shouldn't we do it the same way as the Kernel does it?

Best regards

Heinrich

> ---
>  drivers/sysreset/sysreset_x86.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/sysreset/sysreset_x86.c b/drivers/sysreset/sysreset_x86.c
> index 20b958cfd4..009f376602 100644
> --- a/drivers/sysreset/sysreset_x86.c
> +++ b/drivers/sysreset/sysreset_x86.c
> @@ -10,8 +10,10 @@
>  #include <sysreset.h>
>  #include <asm/io.h>
>  #include <asm/processor.h>
> +#include <efi_loader.h>
>  
> -static int x86_sysreset_request(struct udevice *dev, enum sysreset_t type)
> +static __efi_runtime int x86_sysreset_request(struct udevice *dev,
> +					      enum sysreset_t type)
>  {
>  	int value;
>  
> @@ -31,6 +33,25 @@ static int x86_sysreset_request(struct udevice *dev, enum sysreset_t type)
>  	return -EINPROGRESS;
>  }
>  
> +#ifdef CONFIG_EFI_LOADER
> +void __efi_runtime EFIAPI efi_reset_system(
> +			enum efi_reset_type reset_type,
> +			efi_status_t reset_status,
> +			unsigned long data_size, void *reset_data)
> +{
> +	if (reset_type == EFI_RESET_COLD ||
> +		 reset_type == EFI_RESET_PLATFORM_SPECIFIC)
> +		x86_sysreset_request(NULL, SYSRESET_COLD);
> +	else if (reset_type == EFI_RESET_WARM)
> +		x86_sysreset_request(NULL, SYSRESET_WARM);
> +
> +	/* TODO EFI_RESET_SHUTDOWN */
> +
> +	while (1) { }
> +}
> +#endif
> +
> +
>  static const struct udevice_id x86_sysreset_ids[] = {
>  	{ .compatible = "x86,reset" },
>  	{ }
>