1 files changed, 89 insertions, 0 deletions
diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index f93a735ba327..5062699cbb12 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -222,6 +222,95 @@ static void at91_pm_set_standby(void (*at91_standby)(void))
 		at91_cpuidle_device.dev.platform_data = at91_standby;
 }
 
+/*
+ * The AT91RM9200 goes into self-refresh mode with this command, and will
+ * terminate self-refresh automatically on the next SDRAM access.
+ *
+ * Self-refresh mode is exited as soon as a memory access is made, but we don't
+ * know for sure when that happens. However, we need to restore the low-power
+ * mode if it was enabled before going idle. Restoring low-power mode while
+ * still in self-refresh is "not recommended", but seems to work.
+ */
+static void at91rm9200_standby(void)
+{
+	u32 lpr = at91_ramc_read(0, AT91RM9200_SDRAMC_LPR);
+
+	asm volatile(
+		"b    1f\n\t"
+		".align    5\n\t"
+		"1:  mcr    p15, 0, %0, c7, c10, 4\n\t"
+		"    str    %0, [%1, %2]\n\t"
+		"    str    %3, [%1, %4]\n\t"
+		"    mcr    p15, 0, %0, c7, c0, 4\n\t"
+		"    str    %5, [%1, %2]"
+		:
+		: "r" (0), "r" (at91_ramc_base[0]), "r" (AT91RM9200_SDRAMC_LPR),
+		  "r" (1), "r" (AT91RM9200_SDRAMC_SRR),
+		  "r" (lpr));
+}
+
+/* We manage both DDRAM/SDRAM controllers, we need more than one value to
+ * remember.
+ */
+static void at91_ddr_standby(void)
+{
+	/* Those two values allow us to delay self-refresh activation
+	 * to the maximum. */
+	u32 lpr0, lpr1 = 0;
+	u32 saved_lpr0, saved_lpr1 = 0;
+
+	if (at91_ramc_base[1]) {
+		saved_lpr1 = at91_ramc_read(1, AT91_DDRSDRC_LPR);
+		lpr1 = saved_lpr1 & ~AT91_DDRSDRC_LPCB;
+		lpr1 |= AT91_DDRSDRC_LPCB_SELF_REFRESH;
+	}
+
+	saved_lpr0 = at91_ramc_read(0, AT91_DDRSDRC_LPR);
+	lpr0 = saved_lpr0 & ~AT91_DDRSDRC_LPCB;
+	lpr0 |= AT91_DDRSDRC_LPCB_SELF_REFRESH;
+
+	/* self-refresh mode now */
+	at91_ramc_write(0, AT91_DDRSDRC_LPR, lpr0);
+	if (at91_ramc_base[1])
+		at91_ramc_write(1, AT91_DDRSDRC_LPR, lpr1);
+
+	cpu_do_idle();
+
+	at91_ramc_write(0, AT91_DDRSDRC_LPR, saved_lpr0);
+	if (at91_ramc_base[1])
+		at91_ramc_write(1, AT91_DDRSDRC_LPR, saved_lpr1);
+}
+
+/* We manage both DDRAM/SDRAM controllers, we need more than one value to
+ * remember.
+ */
+static void at91sam9_sdram_standby(void)
+{
+	u32 lpr0, lpr1 = 0;
+	u32 saved_lpr0, saved_lpr1 = 0;
+
+	if (at91_ramc_base[1]) {
+		saved_lpr1 = at91_ramc_read(1, AT91_SDRAMC_LPR);
+		lpr1 = saved_lpr1 & ~AT91_SDRAMC_LPCB;
+		lpr1 |= AT91_SDRAMC_LPCB_SELF_REFRESH;
+	}
+
+	saved_lpr0 = at91_ramc_read(0, AT91_SDRAMC_LPR);
+	lpr0 = saved_lpr0 & ~AT91_SDRAMC_LPCB;
+	lpr0 |= AT91_SDRAMC_LPCB_SELF_REFRESH;
+
+	/* self-refresh mode now */
+	at91_ramc_write(0, AT91_SDRAMC_LPR, lpr0);
+	if (at91_ramc_base[1])
+		at91_ramc_write(1, AT91_SDRAMC_LPR, lpr1);
+
+	cpu_do_idle();
+
+	at91_ramc_write(0, AT91_SDRAMC_LPR, saved_lpr0);
+	if (at91_ramc_base[1])
+		at91_ramc_write(1, AT91_SDRAMC_LPR, saved_lpr1);
+}
+
 static const struct of_device_id ramc_ids[] __initconst = {
 	{ .compatible = "atmel,at91rm9200-sdramc", .data = at91rm9200_standby },
 	{ .compatible = "atmel,at91sam9260-sdramc", .data = at91sam9_sdram_standby },