firmware: Move scratch setup to _start instead of _start_warm

Scratch space setup needs to be done once for reboot for each
hart. _start_warm may be called several times if hart hotplug
is implemented.

Move scratch space setup to the beginning so that it is done
only once.

Signed-off-by: Atish Patra <atish.patra@wdc.com>

diff --git a/firmware/fw_base.S b/firmware/fw_base.S
index 69cfc90..3bf7c6a 100644 (file)
--- a/firmware/fw_base.S
+++ b/firmware/fw_base.S
@@ -27,6 +27,63 @@ _start:
 
        li      ra, 0
        call    _reset_regs
+
+       /* Preload HART details
+        * s7 -> HART Count
+        * s8 -> HART Stack Size
+        */
+       la      a4, platform
+#if __riscv_xlen == 64
+       lwu     s7, SBI_PLATFORM_HART_COUNT_OFFSET(a4)
+       lwu     s8, SBI_PLATFORM_HART_STACK_SIZE_OFFSET(a4)
+#else
+       lw      s7, SBI_PLATFORM_HART_COUNT_OFFSET(a4)
+       lw      s8, SBI_PLATFORM_HART_STACK_SIZE_OFFSET(a4)
+#endif
+
+       /* Setup scratch space for all the HARTs*/
+       la      tp, _fw_end
+       mul     a5, s7, s8
+       add     tp, tp, a5
+       /* Keep a copy of tp */
+       add     t3, tp, zero
+       /* Counter */
+       li      t2, 1
+       /* hartid 0 is mandated by ISA */
+       li      t1, 0
+_scratch_init:
+       add     tp, t3, zero
+       mul     a5, s8, t1
+       sub     tp, tp, a5
+       li      a5, SBI_SCRATCH_SIZE
+       sub     tp, tp, a5
+
+       /* Initialize scratch space */
+       la      a4, _fw_start
+       la      a5, _fw_end
+       mul     t0, s7, s8
+       add     a5, a5, t0
+       sub     a5, a5, a4
+       REG_S   a4, SBI_SCRATCH_FW_START_OFFSET(tp)
+       REG_S   a5, SBI_SCRATCH_FW_SIZE_OFFSET(tp)
+       /* Note: fw_next_arg1() uses a0, a1, and ra */
+       call    fw_next_arg1
+       REG_S   a0, SBI_SCRATCH_NEXT_ARG1_OFFSET(tp)
+       /* Note: fw_next_addr() uses a0, a1, and ra */
+       call    fw_next_addr
+       REG_S   a0, SBI_SCRATCH_NEXT_ADDR_OFFSET(tp)
+       li      a4, PRV_S
+       REG_S   a4, SBI_SCRATCH_NEXT_MODE_OFFSET(tp)
+       la      a4, _start_warm
+       REG_S   a4, SBI_SCRATCH_WARMBOOT_ADDR_OFFSET(tp)
+       la      a4, platform
+       REG_S   a4, SBI_SCRATCH_PLATFORM_ADDR_OFFSET(tp)
+       la      a4, _hartid_to_scratch
+       REG_S   a4, SBI_SCRATCH_HARTID_TO_SCRATCH_OFFSET(tp)
+       REG_S   zero, SBI_SCRATCH_TMP0_OFFSET(tp)
+       add     t1, t1, t2
+       blt     t1, s7, _scratch_init
+
        /* Zero-out BSS */
        la      a4, _bss_start
        la      a5, _bss_end
@@ -132,12 +189,6 @@ _start_warm:
        csrw    CSR_MIE, zero
        csrw    CSR_MIP, zero
 
-       /* Preload per-HART details
-        * s6 -> HART ID
-        * s7 -> HART Count
-        * s8 -> HART Stack Size
-        */
-       csrr    s6, CSR_MHARTID
        la      a4, platform
 #if __riscv_xlen == 64
        lwu     s7, SBI_PLATFORM_HART_COUNT_OFFSET(a4)
@@ -151,7 +202,7 @@ _start_warm:
        csrr    s6, CSR_MHARTID
        bge     s6, s7, _start_hang
 
-       /* Setup scratch space */
+       /* find the scratch space for this hart */
        la      tp, _fw_end
        mul     a5, s7, s8
        add     tp, tp, a5
@@ -159,31 +210,9 @@ _start_warm:
        sub     tp, tp, a5
        li      a5, SBI_SCRATCH_SIZE
        sub     tp, tp, a5
-       csrw    CSR_MSCRATCH, tp
 
-       /* Initialize scratch space */
-       la      a4, _fw_start
-       la      a5, _fw_end
-       mul     t0, s7, s8
-       add     a5, a5, t0
-       sub     a5, a5, a4
-       REG_S   a4, SBI_SCRATCH_FW_START_OFFSET(tp)
-       REG_S   a5, SBI_SCRATCH_FW_SIZE_OFFSET(tp)
-       /* Note: fw_next_arg1() uses a0, a1, and ra */
-       call    fw_next_arg1
-       REG_S   a0, SBI_SCRATCH_NEXT_ARG1_OFFSET(tp)
-       /* Note: fw_next_addr() uses a0, a1, and ra */
-       call    fw_next_addr
-       REG_S   a0, SBI_SCRATCH_NEXT_ADDR_OFFSET(tp)
-       li      a4, PRV_S
-       REG_S   a4, SBI_SCRATCH_NEXT_MODE_OFFSET(tp)
-       la      a4, _start_warm
-       REG_S   a4, SBI_SCRATCH_WARMBOOT_ADDR_OFFSET(tp)
-       la      a4, platform
-       REG_S   a4, SBI_SCRATCH_PLATFORM_ADDR_OFFSET(tp)
-       la      a4, _hartid_to_scratch
-       REG_S   a4, SBI_SCRATCH_HARTID_TO_SCRATCH_OFFSET(tp)
-       REG_S   zero, SBI_SCRATCH_TMP0_OFFSET(tp)
+       /* update the mscratch */
+       csrw    CSR_MSCRATCH, tp
 
        /* Setup stack */
        add     sp, tp, zero