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>

3 files changed, 166 insertions, 5 deletions

diff --git a/arch/sh/kernel/cpu/sh3/Makefile b/arch/sh/kernel/cpu/sh3/Makefile
index e07c69e16d9b..ecab274141a8 100644
--- a/arch/sh/kernel/cpu/sh3/Makefile
+++ b/arch/sh/kernel/cpu/sh3/Makefile
@@ -4,6 +4,8 @@
 
 obj-y	:= ex.o probe.o entry.o setup-sh3.o
 
+obj-$(CONFIG_HIBERNATION)		+= swsusp.o
+
 # CPU subtype setup
 obj-$(CONFIG_CPU_SUBTYPE_SH7705)	+= setup-sh7705.o
 obj-$(CONFIG_CPU_SUBTYPE_SH7706)	+= setup-sh770x.o
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
 
diff --git a/arch/sh/kernel/cpu/sh3/swsusp.S b/arch/sh/kernel/cpu/sh3/swsusp.S
new file mode 100644
index 000000000000..01145426a2b8
--- /dev/null
+++ b/arch/sh/kernel/cpu/sh3/swsusp.S
@@ -0,0 +1,147 @@
+/*
+ * arch/sh/kernel/cpu/sh3/swsusp.S
+ *
+ * Copyright (C) 2009 Magnus Damm
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/sys.h>
+#include <linux/errno.h>
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/page.h>
+
+#define k0	r0
+#define k1	r1
+#define k2	r2
+#define k3	r3
+#define k4	r4
+
+! swsusp_arch_resume()
+! - copy restore_pblist pages
+! - restore registers from swsusp_arch_regs_cpu0
+
+ENTRY(swsusp_arch_resume)
+	mov.l	1f, r15
+	mov.l	2f, r4
+	mov.l	@r4, r4
+
+swsusp_copy_loop:
+	mov	r4, r0
+	cmp/eq	#0, r0
+	bt	swsusp_restore_regs
+
+	mov.l	@(PBE_ADDRESS, r4), r2
+	mov.l	@(PBE_ORIG_ADDRESS, r4), r5
+
+	mov	#(PAGE_SIZE >> 10), r3
+	shll8	r3
+	shlr2	r3 /* PAGE_SIZE / 16 */
+swsusp_copy_page:
+	dt	r3
+	mov.l	@r2+,r1   /*  16n+0 */
+	mov.l	r1,@r5
+	add	#4,r5
+	mov.l	@r2+,r1	  /*  16n+4 */
+	mov.l	r1,@r5
+	add	#4,r5
+	mov.l	@r2+,r1   /*  16n+8 */
+	mov.l	r1,@r5
+	add	#4,r5
+	mov.l	@r2+,r1   /*  16n+12 */
+	mov.l	r1,@r5
+	bf/s	swsusp_copy_page
+	 add	#4,r5
+
+	bra	swsusp_copy_loop
+	 mov.l	@(PBE_NEXT, r4), r4
+
+swsusp_restore_regs:
+	! BL=0: R7->R0 is bank0
+	mov.l	3f, r8
+	mov.l	4f, r5
+	jsr	@r5
+	 nop
+
+	! BL=1: R7->R0 is bank1
+	lds	k2, pr
+	ldc	k3, ssr
+
+	mov.l	@r15+, r0
+	mov.l	@r15+, r1
+	mov.l	@r15+, r2
+	mov.l	@r15+, r3
+	mov.l	@r15+, r4
+	mov.l	@r15+, r5
+	mov.l	@r15+, r6
+	mov.l	@r15+, r7
+
+	rte
+	 nop
+	! BL=0: R7->R0 is bank0
+
+	.align	2
+1:	.long	swsusp_arch_regs_cpu0
+2:	.long	restore_pblist
+3:	.long	0x20000000 ! RB=1
+4:	.long	restore_regs
+
+! swsusp_arch_suspend()
+! - prepare pc for resume, return from function without swsusp_save on resume
+! - save registers in swsusp_arch_regs_cpu0
+! - call swsusp_save write suspend image
+
+ENTRY(swsusp_arch_suspend)
+	sts	pr, r0		! save pr in r0
+	mov	r15, r2		! save sp in r2
+	mov	r8, r5		! save r8 in r5
+	stc	sr, r1
+	ldc	r1, ssr		! save sr in ssr
+	mov.l	1f, r1
+	ldc	r1, spc		! setup pc value for resuming
+	mov.l	5f, r15		! use swsusp_arch_regs_cpu0 as stack
+	mov.l	6f, r3
+	add	r3, r15		! save from top of structure
+
+	! BL=0: R7->R0 is bank0
+	mov.l	2f, r3		! get new SR value for bank1
+	mov	#0, r4
+	mov.l	7f, r1
+	jsr	@r1		! switch to bank1 and save bank1 r7->r0
+	 not	r4, r4
+
+	! BL=1: R7->R0 is bank1
+	stc	r2_bank, k0	! fetch old sp from r2_bank0
+	mov.l	3f, k4		! SR bits to clear in k4
+	mov.l	8f, k1
+	jsr	@k1		! switch to bank0 and save all regs
+	 stc	r0_bank, k3	! fetch old pr from r0_bank0
+
+	! BL=0: R7->R0 is bank0
+	mov	r2, r15		! restore old sp
+	mov	r5, r8		! restore old r8
+	stc	ssr, r1
+	ldc	r1, sr		! restore old sr
+	lds	r0, pr		! restore old pr
+	mov.l	4f, r0
+	jmp	@r0
+	 nop
+
+swsusp_call_save:
+	mov	r2, r15		! restore old sp
+	mov	r5, r8		! restore old r8
+	lds	r0, pr		! restore old pr
+	rts
+	 mov	#0, r0
+
+	.align	2
+1:	.long	swsusp_call_save
+2:	.long	0x20000000 ! RB=1
+3:	.long	0xdfffffff ! RB=0
+4:	.long	swsusp_save
+5:	.long	swsusp_arch_regs_cpu0
+6:	.long	SWSUSP_ARCH_REGS_SIZE
+7:	.long	save_low_regs
+8:	.long	save_regs