arch/riscv: Add OPENSBI_FW_DYNAMIC_BOOT_HART option

This adds another option to tell OpenSBI which hart to use for booting.

Test: Start hifive-unmatched board and see that Hart 1 (instead of 0) is
used for running OpenSBI.

Signed-off-by: Maximilian Brune <maximilian.brune@9elements.com>
Change-Id: Id58bd6ae3b55a5ef3f1a5c97dfa07c79aa4c78d0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79948
Reviewed-by: Philipp Hug <philipp@hug.cx>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/arch/riscv/Kconfig

@@ -66,6 +66,16 @@ config OPENSBI_TEXT_START
 	help
 	  The linking address used to build opensbi.
 
+config OPENSBI_FW_DYNAMIC_BOOT_HART
+	int
+	default RISCV_WORKING_HARTID
+	help
+	  This specifies the hart that OpenSBI will use to boot the payload. If set to
+	  value -1, OpenSBI will use a 'lottery' scheme to figure it out itself.
+	  This hart must be able to execute in the Supervisor priviledged mode, since
+	  that is the mode usually used for the payload. If the hart does not support
+	  Supervisor mode OpenSBI will again look for a hart that does support it.
+
 config ARCH_RISCV_U
 	# U (user) mode is for programs.
 	bool

src/arch/riscv/opensbi.c

@@ -20,6 +20,8 @@ void run_opensbi(const int hart_id,
 		.version = FW_DYNAMIC_INFO_VERSION_MAX,
 		.next_mode = payload_mode,
 		.next_addr = (uintptr_t)payload,
+		.options = 0,
+		.boot_hart = CONFIG_OPENSBI_FW_DYNAMIC_BOOT_HART,
 	};
 
 	csr_write(mepc, opensbi);