[PATCH] ARM: 2781/2: PXA27x Standby mode take 2

Patch from Todd Poynor

Add support for PXA27x Standby mode, a low-power mode that retains CPU
and some peripheral state (the existing "sleep" mode is a power-power
mode that retains less state). Activated via:
echo -n standby > /sys/power/state
From: David Burrage and Todd Poynor

Signed-off-by: Todd Poynor <tpoynor@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-pxa/Makefile

@@ -24,3 +24,7 @@ obj-$(CONFIG_LEDS) += $(led-y)
 
 # Misc features
 obj-$(CONFIG_PM) += pm.o sleep.o
+
+ifeq ($(CONFIG_PXA27x),y)
+obj-$(CONFIG_PM) += standby.o
+endif

arch/arm/mach-pxa/pxa27x.c

@@ -126,6 +126,7 @@ int pxa_cpu_pm_prepare(suspend_state_t state)
 {
 	switch (state) {
 	case PM_SUSPEND_MEM:
+	case PM_SUSPEND_STANDBY:
 		return 0;
 	default:
 		return -EINVAL;
@@ -138,7 +139,10 @@ void pxa_cpu_pm_enter(suspend_state_t state)
 	extern void pxa_cpu_suspend(unsigned int);
 	extern void pxa_cpu_resume(void);
 
-	CKEN = CKEN22_MEMC | CKEN9_OSTIMER;
+	if (state == PM_SUSPEND_STANDBY)
+		CKEN = CKEN22_MEMC | CKEN9_OSTIMER | CKEN16_LCD |CKEN0_PWM0;
+	else
+		CKEN = CKEN22_MEMC | CKEN9_OSTIMER;
 
 	/* ensure voltage-change sequencer not initiated, which hangs */
 	PCFR &= ~PCFR_FVC;
@@ -147,6 +151,9 @@ void pxa_cpu_pm_enter(suspend_state_t state)
 	PEDR = 0xDF12FE1B;
 
 	switch (state) {
+	case PM_SUSPEND_STANDBY:
+		pxa_cpu_standby();
+		break;
 	case PM_SUSPEND_MEM:
 		/* set resume return address */
 		PSPR = virt_to_phys(pxa_cpu_resume);

arch/arm/mach-pxa/standby.S

@@ -0,0 +1,32 @@
+/*
+ * PXA27x standby mode
+ *
+ * Author: David Burrage
+ *
+ * 2005 (c) MontaVista Software, Inc. This file is licensed under
+ * the terms of the GNU General Public License version 2. This program
+ * is licensed "as is" without any warranty of any kind, whether express
+ * or implied.
+ */
+
+#include <linux/config.h>
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/hardware.h>
+
+#include <asm/arch/pxa-regs.h>
+
+		.text
+
+ENTRY(pxa_cpu_standby)
+	ldr	r0, =PSSR
+	mov	r1, #(PSSR_PH | PSSR_STS)
+	mov	r2, #2
+	mov	r3, #UNCACHED_PHYS_0	@ Read mem context in.
+	ldr	ip, [r3]
+	b	1f
+
+	.align	5
+1:	mcr	p14, 0, r2, c7, c0, 0	@ put the system into Standby
+	str	r1, [r0]		@ make sure PSSR_PH/STS are clear
+	mov	pc, lr

include/asm-arm/arch-pxa/pxa-regs.h

@@ -1505,6 +1505,7 @@
 #define PSSR_OTGPH	(1 << 6)	/* OTG Peripheral control Hold */
 #define PSSR_RDH	(1 << 5)	/* Read Disable Hold */
 #define PSSR_PH		(1 << 4)	/* Peripheral Control Hold */
+#define PSSR_STS	(1 << 3)	/* Standby Mode Status */
 #define PSSR_VFS	(1 << 2)	/* VDD Fault Status */
 #define PSSR_BFS	(1 << 1)	/* Battery Fault Status */
 #define PSSR_SSS	(1 << 0)	/* Software Sleep Status */