firmware: Introduce relocation lottery

Instead of forcing HART0 to do the relocation and scratch init
work, we should have an atomic lottery to decide which HART does
the relocation and scratch init.

This way any HART can be boot/main HART.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>

diff --git a/firmware/fw_base.S b/firmware/fw_base.S
index 2c198cf..375c158 100644 (file)
--- a/firmware/fw_base.S
+++ b/firmware/fw_base.S
@@ -46,12 +46,11 @@
        .globl _start
        .globl _start_warm
 _start:
-       /*
-        * Jump to warm-boot if this is not the first core booting,
-        * that is, for mhartid != 0
-        */
-       csrr    a6, CSR_MHARTID
-       blt     zero, a6, _wait_relocate_copy_done
+       /* Jump to relocation wait loop if we don't get relocation lottery */
+       la      a6, _relocate_lottery
+       li      a7, 1
+       amoadd.w a6, a7, (a6)
+       bnez    a6, _wait_relocate_copy_done
 
        /* Save load address */
        la      t0, _load_start
@@ -75,6 +74,8 @@ _relocate:
        blt     t2, t0, _relocate_copy_to_upper
 _relocate_copy_to_lower:
        ble     t1, t2, _relocate_copy_to_lower_loop
+       la      t3, _relocate_lottery
+       BRANGE  t2, t1, t3, _start_hang
        la      t3, _boot_status
        BRANGE  t2, t1, t3, _start_hang
        la      t3, _relocate
@@ -91,6 +92,8 @@ _relocate_copy_to_lower_loop:
        jr      t4
 _relocate_copy_to_upper:
        ble     t3, t0, _relocate_copy_to_upper_loop
+       la      t2, _relocate_lottery
+       BRANGE  t0, t3, t2, _start_hang
        la      t2, _boot_status
        BRANGE  t0, t3, t2, _start_hang
        la      t2, _relocate
@@ -381,6 +384,8 @@ _start_warm:
        j       _start_hang
 
        .align 3
+_relocate_lottery:
+       RISCV_PTR       0
 _boot_status:
        RISCV_PTR       0
 _load_start: