3 files changed, 297 insertions, 0 deletions

diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index 68537e37387f..5aafb2e2ca7a 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -323,6 +323,19 @@ config AT91_PROGRAMMABLE_CLOCKS
           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 a95c49bdf927..cca612d97ca2 100644
--- a/arch/arm/mach-at91/Makefile
+++ b/arch/arm/mach-at91/Makefile
@@ -65,6 +65,7 @@ obj-y				+= leds.o
 
 # 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 000000000000..987fab3d846a
--- /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