sh: hibernation support

Add Suspend-to-disk / swsusp / CONFIG_HIBERNATION support
to the SuperH architecture.

To suspend, use "swapon /dev/sda2; echo disk > /sys/power/state"
To resume, pass "resume=/dev/sda2" on the kernel command line.

The patch "pm: rework includes, remove arch ifdefs V2" is
needed to allow the generic swsusp code to build properly.

Hibernation is not enabled with this patch though, a patch
setting ARCH_HIBERNATION_POSSIBLE will be submitted later.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 17 insertions, 5 deletions

diff --git a/arch/sh/kernel/cpu/sh3/entry.S b/arch/sh/kernel/cpu/sh3/entry.S
index c4829d6dee51..fba6ac20bb17 100644
--- a/arch/sh/kernel/cpu/sh3/entry.S
+++ b/arch/sh/kernel/cpu/sh3/entry.S
@@ -216,7 +216,7 @@ ENTRY(sh_bios_handler)
 ! r9 trashed
 ! BL=0 on entry, on exit BL=1 (depending on r8).
 
-restore_regs:
+ENTRY(restore_regs)
         mov.l   @r15+, r0
         mov.l   @r15+, r1
         mov.l   @r15+, r2
@@ -362,8 +362,10 @@ general_exception:
          nop
 
         ! Save registers / Switch to bank 0
+        mov.l   k4, k2          ! keep vector in k2
+        mov.l   1f, k4          ! SR bits to clear in k4
         bsr     save_regs       ! needs original pr value in k3
-         mov    k4, k2          ! keep vector in k2
+         nop
 
         bra     handle_exception_special
          nop
@@ -471,6 +473,7 @@ handle_exception:
 
         ! Save registers / Switch to bank 0
         mov.l   5f, k2          ! vector register address
+        mov.l   1f, k4          ! SR bits to clear in k4
         bsr     save_regs       ! needs original pr value in k3
          mov.l  @k2, k2         ! read out vector and keep in k2
 
@@ -495,10 +498,10 @@ handle_exception_special:
 ! k0 contains original stack pointer*
 ! k1 trashed
 ! k3 passes original pr*
-! k4 trashed
+! k4 passes SR bitmask
 ! BL=1 on entry, on exit BL=0.
 
-save_regs:
+ENTRY(save_regs)
         mov     #-1, r1
         mov.l   k1, @-r15       ! set TRA (default: -1)
         sts.l   macl, @-r15
@@ -518,8 +521,16 @@ save_regs:
         mov.l   r8, @-r15
 
         mov.l   0f, k3          ! SR bits to set in k3
-        mov.l   1f, k4          ! SR bits to clear in k4
 
+        ! fall-through
+
+! save_low_regs()
+! - modify SR for bank switch
+! - save r7, r6, r5, r4, r3, r2, r1, r0 on the stack
+! k3 passes bits to set in SR
+! k4 passes bits to clear in SR
+
+ENTRY(save_low_regs)
         stc     sr, r8
         or      k3, r8
         and     k4, r8
@@ -565,6 +576,7 @@ ENTRY(handle_interrupt)
          PREF(k0)
 
         ! Save registers / Switch to bank 0
+        mov.l   1f, k4          ! SR bits to clear in k4
         bsr     save_regs       ! needs original pr value in k3
          mov    #-1, k2         ! default vector kept in k2