[1/1] riscv/efi_stub: Add support for RISCV_EFI_BOOT_PROTOCOL

This patch adds the support for getting the boot hart ID in
Linux EFI stub using RISCV_EFI_BOOT_PROTOCOL. This protocol
is preferred method over existing DT based solution since it
works irrespective of DT or ACPI.

The specification of the protocol is hosted at:
https://github.com/riscv-non-isa/riscv-uefi

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
---
 drivers/firmware/efi/libstub/efistub.h    |  7 ++++++
 drivers/firmware/efi/libstub/riscv-stub.c | 29 +++++++++++++++++++----
 include/linux/efi.h                       |  1 +
 3 files changed, 32 insertions(+), 5 deletions(-)

On 3/24/22 12:25, Sunil V L wrote:
> This patch adds the support for getting the boot hart ID in
> Linux EFI stub using RISCV_EFI_BOOT_PROTOCOL. This protocol
> is preferred method over existing DT based solution since it
> works irrespective of DT or ACPI.
> 
> The specification of the protocol is hosted at:
> https://github.com/riscv-non-isa/riscv-uefi
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> Acked-by: Palmer Dabbelt <palmer@rivosinc.com>

This seems to be v3 of the patch. v2 is available in
https://lore.kernel.org/all/20220303145944.307321-2-sunilvl@ventanamicro.com/

v3 replaces a message in efi_status_t check_platform_features():

<+   efi_err("/chosen/boot-hartid missing or invalid!\n");
 >+   efi_err("Failed to get boot hartid!\n");

Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

> ---
>   drivers/firmware/efi/libstub/efistub.h    |  7 ++++++
>   drivers/firmware/efi/libstub/riscv-stub.c | 29 +++++++++++++++++++----
>   include/linux/efi.h                       |  1 +
>   3 files changed, 32 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index edb77b0621ea..aced62a0907e 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -720,6 +720,13 @@ union efi_tcg2_protocol {
>   	} mixed_mode;
>   };
>   
> +struct riscv_efi_boot_protocol {
> +	u64 revision;
> +
> +	efi_status_t (__efiapi * get_boot_hartid)(struct riscv_efi_boot_protocol *this,
> +						  size_t *boot_hartid);
> +};
> +
>   typedef union efi_load_file_protocol efi_load_file_protocol_t;
>   typedef union efi_load_file_protocol efi_load_file2_protocol_t;
>   
> diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
> index 9c460843442f..012504f6f9a4 100644
> --- a/drivers/firmware/efi/libstub/riscv-stub.c
> +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> @@ -23,7 +23,7 @@
>   
>   typedef void __noreturn (*jump_kernel_func)(unsigned int, unsigned long);
>   
> -static u32 hartid;
> +static size_t hartid;
>   
>   static int get_boot_hartid_from_fdt(void)
>   {
> @@ -47,14 +47,33 @@ static int get_boot_hartid_from_fdt(void)
>   	return 0;
>   }
>   
> +static efi_status_t get_boot_hartid_from_efi(void)
> +{
> +	efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
> +	efi_status_t status;
> +	struct riscv_efi_boot_protocol *boot_protocol;
> +
> +	status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
> +			     (void **)&boot_protocol);
> +	if (status == EFI_SUCCESS) {
> +		status = efi_call_proto(boot_protocol,
> +					get_boot_hartid, &hartid);
> +	}
> +	return status;
> +}
> +
>   efi_status_t check_platform_features(void)
>   {
>   	int ret;
> +	efi_status_t status;
>   
> -	ret = get_boot_hartid_from_fdt();
> -	if (ret) {
> -		efi_err("/chosen/boot-hartid missing or invalid!\n");
> -		return EFI_UNSUPPORTED;
> +	status = get_boot_hartid_from_efi();
> +	if (status != EFI_SUCCESS) {
> +		ret = get_boot_hartid_from_fdt();
> +		if (ret) {
> +			efi_err("Failed to get boot hartid!\n");
> +			return EFI_UNSUPPORTED;
> +		}
>   	}
>   	return EFI_SUCCESS;
>   }
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index ccd4d3f91c98..9822c730207c 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -380,6 +380,7 @@ void efi_native_runtime_setup(void);
>   #define EFI_CONSOLE_OUT_DEVICE_GUID		EFI_GUID(0xd3b36f2c, 0xd551, 0x11d4,  0x9a, 0x46, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
>   #define APPLE_PROPERTIES_PROTOCOL_GUID		EFI_GUID(0x91bd12fe, 0xf6c3, 0x44fb,  0xa5, 0xb7, 0x51, 0x22, 0xab, 0x30, 0x3a, 0xe0)
>   #define EFI_TCG2_PROTOCOL_GUID			EFI_GUID(0x607f766c, 0x7455, 0x42be,  0x93, 0x0b, 0xe4, 0xd7, 0x6d, 0xb2, 0x72, 0x0f)
> +#define RISCV_EFI_BOOT_PROTOCOL_GUID		EFI_GUID(0xccd15fec, 0x6f73, 0x4eec,  0x83, 0x95, 0x3e, 0x69, 0xe4, 0xb9, 0x40, 0xbf)
>   #define EFI_LOAD_FILE_PROTOCOL_GUID		EFI_GUID(0x56ec3091, 0x954c, 0x11d2,  0x8e, 0x3f, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b)
>   #define EFI_LOAD_FILE2_PROTOCOL_GUID		EFI_GUID(0x4006c0c1, 0xfcb3, 0x403e,  0x99, 0x6d, 0x4a, 0x6c, 0x87, 0x24, 0xe0, 0x6d)
>   #define EFI_RT_PROPERTIES_TABLE_GUID		EFI_GUID(0xeb66918a, 0x7eef, 0x402a,  0x84, 0x2e, 0x93, 0x1d, 0x21, 0xc3, 0x8a, 0xe9)