qemu: Implement PSCI_CPU_OFF.
This is based on the rpi implementation from
https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/2746.
Signed-off-by: Andrew Walbran <qwandor@google.com>
Change-Id: I5fe324fcd9d5e232091e01267ea12147c46bc9c1
diff --git a/plat/qemu/common/aarch32/plat_helpers.S b/plat/qemu/common/aarch32/plat_helpers.S
index aebcfa7..15e860b 100644
--- a/plat/qemu/common/aarch32/plat_helpers.S
+++ b/plat/qemu/common/aarch32/plat_helpers.S
@@ -72,8 +72,14 @@
/* Wait until we have a go */
poll_mailbox:
ldr r1, [r2, r0]
- cmp r1, #0
+ cmp r1, #PLAT_QEMU_HOLD_STATE_WAIT
beq 1f
+
+ /* Clear the mailbox again ready for next time. */
+ mov r1, #PLAT_QEMU_HOLD_STATE_WAIT
+ str r1, [r2, r0]
+
+ /* Jump to the provided entrypoint. */
mov_imm r0, PLAT_QEMU_TRUSTED_MAILBOX_BASE
ldr r1, [r0]
bx r1