lib: Check MSIP bit after returning from WFI

Commit 71d2b837c46e (lib: Move all coldboot wait APIs to sbi_init.c)
caused a regression while moving the code from sbi_hart.c to sbi_init.c.

As per original commit text, WFI can be implemented as a NOP according
to the RISC-V privilege specification. Software should ensure that
relevant interrupt pending bits are set. Otherwise, loop back to WFI.
Fix the regression by applying the original patch to sbi_init.c.

Fixes: 71d2b837c46e ("lib: Move all coldboot wait APIs to sbi_init.c")

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

diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
index 2b9afb7..90ec64c 100644 (file)
--- a/lib/sbi/sbi_init.c
+++ b/lib/sbi/sbi_init.c
@@ -79,7 +79,7 @@ static struct sbi_hartmask coldboot_wait_hmask = { 0 };
 
 static void wait_for_coldboot(struct sbi_scratch *scratch, u32 hartid)
 {
-       unsigned long saved_mie;
+       unsigned long saved_mie, cmip;
        const struct sbi_platform *plat = sbi_platform_ptr(scratch);
 
        /* Save MIE CSR */
@@ -97,7 +97,10 @@ static void wait_for_coldboot(struct sbi_scratch *scratch, u32 hartid)
        /* Wait for coldboot to finish using WFI */
        while (!coldboot_done) {
                spin_unlock(&coldboot_lock);
-               wfi();
+               do {
+                       wfi();
+                       cmip = csr_read(CSR_MIP);
+                } while (!(cmip & MIP_MSIP));
                spin_lock(&coldboot_lock);
        };