[POWERPC] Add 6xx-style HID0_SLEEP support.

This adds a function to put a 6xx/7xx/7xxx/83xx family CPU into sleep
mode, and return after an interrupt has occurred. It expects to be
called with interrupts disabled, and returns with interrupts disabled.
Interrupts are enabled while the processor is asleep, but the interrupt
that wakes the processor is not handled; it is still pending when this
function returns.

Signed-off-by: Scott Wood <[e-mail]>
Signed-off-by: Guennadi Liakhovetski <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/powerpc/sysdev/6xx-suspend.S

···
+/*
+ * Enter and leave sleep state on chips with 6xx-style HID0
+ * power management bits, which don't leave sleep state via reset.
+ *
+ * Author: Scott Wood <[e-mail]>
+ *
+ * Copyright (c) 2006-2007 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <asm/ppc_asm.h>
+#include <asm/reg.h>
+#include <asm/thread_info.h>
+#include <asm/asm-offsets.h>
+
+_GLOBAL(mpc6xx_enter_standby)
+	mflr	r4
+
+	mfspr	r5, SPRN_HID0
+	rlwinm	r5, r5, 0, ~(HID0_DOZE | HID0_NAP)
+	oris	r5, r5, HID0_SLEEP@h
+	mtspr	SPRN_HID0, r5
+	isync
+
+	lis	r5, ret_from_standby@h
+	ori	r5, r5, ret_from_standby@l
+	mtlr	r5
+
+	rlwinm	r5, r1, 0, 0, 31-THREAD_SHIFT
+	lwz	r6, TI_LOCAL_FLAGS(r5)
+	ori	r6, r6, _TLF_SLEEPING
+	stw	r6, TI_LOCAL_FLAGS(r5)
+
+	mfmsr	r5
+	ori	r5, r5, MSR_EE
+	oris	r5, r5, MSR_POW@h
+	sync
+	mtmsr	r5
+	isync
+
+1:	b	1b
+
+ret_from_standby:
+	mfspr	r5, SPRN_HID0
+	rlwinm	r5, r5, 0, ~HID0_SLEEP
+	mtspr	SPRN_HID0, r5
+
+	mtlr	r4
+	blr

arch/powerpc/sysdev/Makefile

···
 obj-$(CONFIG_8xx)		+= mpc8xx_pic.o cpm1.o
 obj-$(CONFIG_UCODE_PATCH)	+= micropatch.o
 endif
+
+ifeq ($(CONFIG_SUSPEND),y)
+obj-$(CONFIG_6xx)		+= 6xx-suspend.o
+endif

include/asm-powerpc/mpc6xx.h

···
+#ifndef __ASM_POWERPC_MPC6xx_H
+#define __ASM_POWERPC_MPC6xx_H
+
+void mpc6xx_enter_standby(void);
+
+#endif