[PATCH v2 1/1] efi_loader: architecture specific UEFI setup

[Heinrich Schuchardt]

RISC-V booting currently is based on a per boot stage lottery to determine
the active CPU. The Hart State Management (HSM) SBI extension replaces
this lottery by using a dedicated primary CPU.

Cf. Hart State Management Extension, Extension ID: 0x48534D (HSM)
https://github.com/riscv/riscv-sbi-doc/blob/master/riscv-sbi.adoc

In this scenario the id of the active hart has to be passed from boot stage
to boot stage. Using a UEFI variable would provide an easy implementation.

This patch provides a weak function that is called at the end of the setup
of U-Boot's UEFI sub-system. By overriding this function architecture
specific UEFI variables or configuration tables can be created.

Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
Reviewed-by: Atish Patra <atish.patra at wdc.com>
---
v2:
	reference the Hart State Management Extension in the commit message
---
 include/efi_loader.h       |  3 +++
 lib/efi_loader/efi_setup.c | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index d4c59b54c4..d87de85e83 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -116,6 +116,9 @@ extern efi_uintn_t efi_memory_map_key;
 extern struct efi_runtime_services efi_runtime_services;
 extern struct efi_system_table systab;

+/* Architecture specific initialization of the UEFI system */
+efi_status_t efi_setup_arch_specific(void);
+
 extern struct efi_simple_text_output_protocol efi_con_out;
 extern struct efi_simple_text_input_protocol efi_con_in;
 extern struct efi_console_control_protocol efi_console_control;
diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
index de7b616c6d..8469f0f43c 100644
--- a/lib/efi_loader/efi_setup.c
+++ b/lib/efi_loader/efi_setup.c
@@ -22,6 +22,17 @@ void __weak allow_unaligned(void)
 {
 }

+/**
+ * efi_setup_arch_specific() - architecture specific UEFI setup
+ *
+ * This routine can be used to define architecture specific variables
+ * or configuration tables, e.g. HART id for RISC-V
+ */
+efi_status_t __weak efi_setup_arch_specific(void)
+{
+	return EFI_SUCCESS;
+}
+
 /**
  * efi_init_platform_lang() - define supported languages
  *
@@ -179,6 +190,11 @@ efi_status_t efi_init_obj_list(void)
 	if (ret != EFI_SUCCESS)
 		goto out;

+	/* Architecture specific setup */
+	ret = efi_setup_arch_specific();
+	if (ret != EFI_SUCCESS)
+		goto out;
+
 out:
 	efi_obj_list_initialized = ret;
 	return ret;
--
2.24.1