ARM: 8389/1: Add cpu_resume_arm() for firmwares that resume in ARM state

Some platforms always enter the kernel in the ARM state even if
the kernel is compiled for THUMB2. Add a small wrapper on top of
cpu_resume() that switches into THUMB2 state.

This provides the functionality to fix a problem reported by Kevin
Hilman on next-20150601 where the ifc6410 fails to boot a THUMB2
kernel because the platform's firmware always enters the kernel in
ARM mode from deep idle states.

(rmk: tweaked to work without BSYM->badr changes.)

Reported-by: Kevin Hilman <khilman@linaro.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/include/asm/suspend.h b/arch/arm/include/asm/suspend.h
index cd20029..6c7182f 100644 (file)
--- a/arch/arm/include/asm/suspend.h
+++ b/arch/arm/include/asm/suspend.h
@@ -7,6 +7,7 @@ struct sleep_save_sp {
 };
 
 extern void cpu_resume(void);
+extern void cpu_resume_arm(void);
 extern int cpu_suspend(unsigned long, int (*)(unsigned long));
 
 #endif

diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index 7d37bfc..761c5de 100644 (file)
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -118,6 +118,12 @@ ENDPROC(cpu_resume_after_mmu)
 
        .text
        .align
+       .arm
+ENTRY(cpu_resume_arm)
+ THUMB(        adr     r9, BSYM(1f)    )       @ Kernel is entered in ARM.
+ THUMB(        bx      r9              )       @ If this is a Thumb-2 kernel,
+ THUMB(        .thumb                  )       @ switch to Thumb now.
+ THUMB(1:                      )
 ENTRY(cpu_resume)
 ARM_BE8(setend be)                     @ ensure we are in BE mode
 #ifdef CONFIG_ARM_VIRT_EXT
@@ -149,6 +155,7 @@ THUMB(      ldmia   r0!, {r1, r2, r3}       )
 THUMB( mov     sp, r2                  )
 THUMB( bx      r3                      )
 ENDPROC(cpu_resume)
+ENDPROC(cpu_resume_arm)
 
        .align 2
 _sleep_save_sp: