ARM: pm: allow suspend finisher to return error codes
There are SoCs where attempting to enter a low power state is ignored,
and the CPU continues executing instructions with all state preserved.
It is over-complex at that point to disable the MMU just to call the
resume path.
Instead, allow the suspend finisher to return error codes to abort
suspend in this circumstance, where the cpu_suspend internals will then
unwind the saved state on the stack. Also omit the tlb flush as no
changes to the page tables will have happened.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index c156d0e..dc902f2 100644
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -12,7 +12,6 @@
* r1 = v:p offset
* r2 = suspend function arg0
* r3 = suspend function
- * Note: does not return until system resumes
*/
ENTRY(__cpu_suspend)
stmfd sp!, {r4 - r11, lr}
@@ -26,7 +25,7 @@
#endif
mov r6, sp @ current virtual SP
sub sp, sp, r5 @ allocate CPU state on stack
- mov r0, sp @ save pointer
+ mov r0, sp @ save pointer to CPU save block
add ip, ip, r1 @ convert resume fn to phys
stmfd sp!, {r1, r6, ip} @ save v:p, virt SP, phys resume fn
ldr r5, =sleep_save_sp
@@ -55,10 +54,17 @@
#else
bl __cpuc_flush_kern_all
#endif
+ adr lr, BSYM(cpu_suspend_abort)
ldmfd sp!, {r0, pc} @ call suspend fn
ENDPROC(__cpu_suspend)
.ltorg
+cpu_suspend_abort:
+ ldmia sp!, {r1 - r3} @ pop v:p, virt SP, phys resume fn
+ mov sp, r2
+ ldmfd sp!, {r4 - r11, pc}
+ENDPROC(cpu_suspend_abort)
+
/*
* r0 = control register value
* r1 = v:p offset (preserved by cpu_do_resume)
@@ -89,6 +95,7 @@
str r5, [r2, r4, lsl #2] @ restore old mapping
mcr p15, 0, r0, c1, c0, 0 @ turn on D-cache
bl cpu_init @ restore the und/abt/irq banked regs
+ mov r0, #0 @ return zero on success
ldmfd sp!, {r4 - r11, pc}
ENDPROC(cpu_resume_after_mmu)