diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index 68537e3..5aafb2e 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -323,6 +323,19 @@
 	  Select this if you need to program one or more of the PCK0..PCK3
 	  programmable clock outputs.
 
+config AT91_SLOW_CLOCK
+	bool "Suspend-to-RAM disables main oscillator"
+	depends on SUSPEND
+	help
+	  Select this if you want Suspend-to-RAM to save the most power
+	  possible (without powering off the CPU) by disabling the PLLs
+	  and main oscillator so that only the 32 KiHz clock is available.
+
+	  When only that slow-clock is available, some peripherals lose
+	  functionality.  Many can't issue wakeup events unless faster
+	  clocks are available.  Some lose their operating state and
+	  need to be completely re-initialized.
+
 config AT91_TIMER_HZ
        int "Kernel HZ (jiffies per second)"
        range 32 1024
diff --git a/arch/arm/mach-at91/Makefile b/arch/arm/mach-at91/Makefile
index a95c49b..cca612d 100644
--- a/arch/arm/mach-at91/Makefile
+++ b/arch/arm/mach-at91/Makefile
@@ -65,6 +65,7 @@
 
 # Power Management
 obj-$(CONFIG_PM)		+= pm.o
+obj-$(CONFIG_AT91_SLOW_CLOCK)	+= pm_slowclock.o
 
 ifeq ($(CONFIG_PM_DEBUG),y)
 CFLAGS_pm.o += -DDEBUG
diff --git a/arch/arm/mach-at91/pm_slowclock.S b/arch/arm/mach-at91/pm_slowclock.S
new file mode 100644
index 0000000..987fab3
--- /dev/null
+++ b/arch/arm/mach-at91/pm_slowclock.S
@@ -0,0 +1,283 @@
+/*
+ * arch/arm/mach-at91/pm_slow_clock.S
+ *
+ *  Copyright (C) 2006 Savin Zlobec
+ *
+ * AT91SAM9 support:
+ *  Copyright (C) 2007 Anti Sullin <anti.sullin@artecdesign.ee
+ *
+ * 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 <linux/linkage.h>
+#include <mach/hardware.h>
+#include <mach/at91_pmc.h>
+
+#ifdef CONFIG_ARCH_AT91RM9200
+#include <mach/at91rm9200_mc.h>
+#elif defined(CONFIG_ARCH_AT91CAP9)
+#include <mach/at91cap9_ddrsdr.h>
+#else
+#include <mach/at91sam9_sdramc.h>
+#endif
+
+
+#ifdef CONFIG_ARCH_AT91SAM9263
+/*
+ * FIXME either or both the SDRAM controllers (EB0, EB1) might be in use;
+ * handle those cases both here and in the Suspend-To-RAM support.
+ */
+#define AT91_SDRAMC	AT91_SDRAMC0
+#warning Assuming EB1 SDRAM controller is *NOT* used
+#endif
+
+/*
+ * When SLOWDOWN_MASTER_CLOCK is defined we will also slow down the Master
+ * clock during suspend by adjusting its prescalar and divisor.
+ * NOTE: This hasn't been shown to be stable on SAM9s; and on the RM9200 there
+ *       are errata regarding adjusting the prescalar and divisor.
+ */
+#undef SLOWDOWN_MASTER_CLOCK
+
+#define MCKRDY_TIMEOUT		1000
+#define MOSCRDY_TIMEOUT 	1000
+#define PLLALOCK_TIMEOUT	1000
+#define PLLBLOCK_TIMEOUT	1000
+
+
+/*
+ * Wait until master clock is ready (after switching master clock source)
+ */
+	.macro wait_mckrdy
+	mov	r4, #MCKRDY_TIMEOUT
+1:	sub	r4, r4, #1
+	cmp	r4, #0
+	beq	2f
+	ldr	r3, [r1, #(AT91_PMC_SR - AT91_PMC)]
+	tst	r3, #AT91_PMC_MCKRDY
+	beq	1b
+2:
+	.endm
+
+/*
+ * Wait until master oscillator has stabilized.
+ */
+	.macro wait_moscrdy
+	mov	r4, #MOSCRDY_TIMEOUT
+1:	sub	r4, r4, #1
+	cmp	r4, #0
+	beq	2f
+	ldr	r3, [r1, #(AT91_PMC_SR - AT91_PMC)]
+	tst	r3, #AT91_PMC_MOSCS
+	beq	1b
+2:
+	.endm
+
+/*
+ * Wait until PLLA has locked.
+ */
+	.macro wait_pllalock
+	mov	r4, #PLLALOCK_TIMEOUT
+1:	sub	r4, r4, #1
+	cmp	r4, #0
+	beq	2f
+	ldr	r3, [r1, #(AT91_PMC_SR - AT91_PMC)]
+	tst	r3, #AT91_PMC_LOCKA
+	beq	1b
+2:
+	.endm
+
+/*
+ * Wait until PLLB has locked.
+ */
+	.macro wait_pllblock
+	mov	r4, #PLLBLOCK_TIMEOUT
+1:	sub	r4, r4, #1
+	cmp	r4, #0
+	beq	2f
+	ldr	r3, [r1, #(AT91_PMC_SR - AT91_PMC)]
+	tst	r3, #AT91_PMC_LOCKB
+	beq	1b
+2:
+	.endm
+
+	.text
+
+ENTRY(at91_slow_clock)
+	/* Save registers on stack */
+	stmfd	sp!, {r0 - r12, lr}
+
+	/*
+	 * Register usage:
+	 *  R1 = Base address of AT91_PMC
+	 *  R2 = Base address of AT91_SDRAMC (or AT91_SYS on AT91RM9200)
+	 *  R3 = temporary register
+	 *  R4 = temporary register
+	 */
+	ldr	r1, .at91_va_base_pmc
+	ldr	r2, .at91_va_base_sdramc
+
+	/* Drain write buffer */
+	mcr	p15, 0, r0, c7, c10, 4
+
+#ifdef CONFIG_ARCH_AT91RM9200
+	/* Put SDRAM in self-refresh mode */
+	mov	r3, #1
+	str	r3, [r2, #AT91_SDRAMC_SRR]
+#elif defined(CONFIG_ARCH_AT91CAP9)
+	/* Enable SDRAM self-refresh mode */
+	ldr	r3, [r2, #AT91_DDRSDRC_LPR - AT91_DDRSDRC]
+	str	r3, .saved_sam9_lpr
+
+	mov	r3, #AT91_DDRSDRC_LPCB_SELF_REFRESH
+	str	r3, [r2, #AT91_DDRSDRC_LPR - AT91_DDRSDRC]
+#else
+	/* Enable SDRAM self-refresh mode */
+	ldr	r3, [r2, #AT91_SDRAMC_LPR - AT91_SDRAMC]
+	str	r3, .saved_sam9_lpr
+
+	mov	r3, #AT91_SDRAMC_LPCB_SELF_REFRESH
+	str	r3, [r2, #AT91_SDRAMC_LPR - AT91_SDRAMC]
+#endif
+
+	/* Save Master clock setting */
+	ldr	r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
+	str	r3, .saved_mckr
+
+	/*
+	 * Set the Master clock source to slow clock
+	 */
+	bic	r3, r3, #AT91_PMC_CSS
+	str	r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
+
+	wait_mckrdy
+
+#ifdef SLOWDOWN_MASTER_CLOCK
+	/*
+	 * Set the Master Clock PRES and MDIV fields.
+	 *
+	 * See AT91RM9200 errata #27 and #28 for details.
+	 */
+	mov	r3, #0
+	str	r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
+
+	wait_mckrdy
+#endif
+
+	/* Save PLLA setting and disable it */
+	ldr	r3, [r1, #(AT91_CKGR_PLLAR - AT91_PMC)]
+	str	r3, .saved_pllar
+
+	mov	r3, #AT91_PMC_PLLCOUNT
+	orr	r3, r3, #(1 << 29)		/* bit 29 always set */
+	str	r3, [r1, #(AT91_CKGR_PLLAR - AT91_PMC)]
+
+	wait_pllalock
+
+	/* Save PLLB setting and disable it */
+	ldr	r3, [r1, #(AT91_CKGR_PLLBR - AT91_PMC)]
+	str	r3, .saved_pllbr
+
+	mov	r3, #AT91_PMC_PLLCOUNT
+	str	r3, [r1, #(AT91_CKGR_PLLBR - AT91_PMC)]
+
+	wait_pllblock
+
+	/* Turn off the main oscillator */
+	ldr	r3, [r1, #(AT91_CKGR_MOR - AT91_PMC)]
+	bic	r3, r3, #AT91_PMC_MOSCEN
+	str	r3, [r1, #(AT91_CKGR_MOR - AT91_PMC)]
+
+	/* Wait for interrupt */
+	mcr	p15, 0, r0, c7, c0, 4
+
+	/* Turn on the main oscillator */
+	ldr	r3, [r1, #(AT91_CKGR_MOR - AT91_PMC)]
+	orr	r3, r3, #AT91_PMC_MOSCEN
+	str	r3, [r1, #(AT91_CKGR_MOR - AT91_PMC)]
+
+	wait_moscrdy
+
+	/* Restore PLLB setting */
+	ldr	r3, .saved_pllbr
+	str	r3, [r1, #(AT91_CKGR_PLLBR - AT91_PMC)]
+
+	wait_pllblock
+
+	/* Restore PLLA setting */
+	ldr	r3, .saved_pllar
+	str	r3, [r1, #(AT91_CKGR_PLLAR - AT91_PMC)]
+
+	wait_pllalock
+
+#ifdef SLOWDOWN_MASTER_CLOCK
+	/*
+	 * First set PRES if it was not 0,
+	 * than set CSS and MDIV fields.
+	 *
+	 * See AT91RM9200 errata #27 and #28 for details.
+	 */
+	ldr	r3, .saved_mckr
+	tst	r3, #AT91_PMC_PRES
+	beq	2f
+	and	r3, r3, #AT91_PMC_PRES
+	str	r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
+
+	wait_mckrdy
+#endif
+
+	/*
+	 * Restore master clock setting
+	 */
+2:	ldr	r3, .saved_mckr
+	str	r3, [r1, #(AT91_PMC_MCKR - AT91_PMC)]
+
+	wait_mckrdy
+
+#ifdef CONFIG_ARCH_AT91RM9200
+	/* Do nothing - self-refresh is automatically disabled. */
+#elif defined(CONFIG_ARCH_AT91CAP9)
+	/* Restore LPR on AT91CAP9 */
+	ldr	r3, .saved_sam9_lpr
+	str	r3, [r2, #AT91_DDRSDRC_LPR - AT91_DDRSDRC]
+#else
+	/* Restore LPR on AT91SAM9 */
+	ldr	r3, .saved_sam9_lpr
+	str	r3, [r2, #AT91_SDRAMC_LPR - AT91_SDRAMC]
+#endif
+
+	/* Restore registers, and return */
+	ldmfd	sp!, {r0 - r12, pc}
+
+
+.saved_mckr:
+	.word 0
+
+.saved_pllar:
+	.word 0
+
+.saved_pllbr:
+	.word 0
+
+.saved_sam9_lpr:
+	.word 0
+
+.at91_va_base_pmc:
+	.word AT91_VA_BASE_SYS + AT91_PMC
+
+#ifdef CONFIG_ARCH_AT91RM9200
+.at91_va_base_sdramc:
+	.word AT91_VA_BASE_SYS
+#elif defined(CONFIG_ARCH_AT91CAP9)
+.at91_va_base_sdramc:
+	.word AT91_VA_BASE_SYS + AT91_DDRSDRC
+#else
+.at91_va_base_sdramc:
+	.word AT91_VA_BASE_SYS + AT91_SDRAMC
+#endif
+
+ENTRY(at91_slow_clock_sz)
+	.word .-at91_slow_clock