[RFC PATCH v2 1/2] arch: riscv: cpu: Add callback to init each core

[Green Wan <green.wan@sifive.com>]

Add a callback riscv_hart_early_init() to ./arch/riscv/cpu/start.S to
allow different riscv hart perform setup code for each hart as early
as possible. Since all the harts enter the calback, they must be able
to run the same setup.

Signed-off-by: Green Wan <green.wan@sifive.com>
---
 arch/riscv/cpu/start.S | 5 +++++
 arch/riscv/lib/spl.c   | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S
index 8589509e01..5c7d4da9e2 100644
--- a/arch/riscv/cpu/start.S
+++ b/arch/riscv/cpu/start.S
@@ -117,6 +117,11 @@ call_board_init_f_0:
 	mv	sp, a0
 #endif
 
+#if CONFIG_IS_ENABLED(RISCV_MMODE)
+call_riscv_hart_early_init:
+	jal	riscv_hart_early_init
+#endif
+
 #ifndef CONFIG_XIP
 	/*
 	 * Pick hart to initialize global data and run U-Boot. The other harts
diff --git a/arch/riscv/lib/spl.c b/arch/riscv/lib/spl.c
index 8baee07bea..e5b1affbfc 100644
--- a/arch/riscv/lib/spl.c
+++ b/arch/riscv/lib/spl.c
@@ -14,6 +14,10 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+__weak void riscv_hart_early_init(void)
+{
+}
+
 __weak int spl_board_init_f(void)
 {
 	return 0;
-- 
2.31.0