ULP0 fast improves suspend/resume time with few milliseconds the drawback
being the power consumption. The mean values measured for suspend/resume
time are as follows (measured on SAMA5D2 Xplained board), ULP0 compared
with fast ULP0:
- ulp0 fast: suspend time: 169 ms, resume time: 216 ms
- ulp0 : suspend time: 197 ms, resume time: 258 ms
Current consumption while suspended (measured on SAMA5D2 Xplained board):
- ulp0 fast: 730uA
- ulp0 : 270uA
Signed-off-by: Claudiu Beznea <claudiu.bez...@microchip.com>
---
arch/arm/mach-at91/pm.c | 9 +++++----
arch/arm/mach-at91/pm.h | 5 +++--
arch/arm/mach-at91/pm_suspend.S | 41 +++++++++++++++++++++++++++++++++++++----
3 files changed, 45 insertions(+), 10 deletions(-)
diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index 074bde64064e..04fdcbd57100 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -51,10 +51,11 @@ static struct at91_soc_pm soc_pm = {
};
static const match_table_t pm_modes __initconst = {
- { AT91_PM_STANDBY, "standby" },
- { AT91_PM_ULP0, "ulp0" },
- { AT91_PM_ULP1, "ulp1" },
- { AT91_PM_BACKUP, "backup" },
+ { AT91_PM_STANDBY, "standby" },
+ { AT91_PM_ULP0, "ulp0" },
+ { AT91_PM_ULP0_FAST, "ulp0-fast" },
+ { AT91_PM_ULP1, "ulp1" },
+ { AT91_PM_BACKUP, "backup" },
{ -1, NULL },
};
diff --git a/arch/arm/mach-at91/pm.h b/arch/arm/mach-at91/pm.h
index 218e8d1a30fb..bfb260be371e 100644
--- a/arch/arm/mach-at91/pm.h
+++ b/arch/arm/mach-at91/pm.h
@@ -19,8 +19,9 @@
#define AT91_PM_STANDBY 0x00
#define AT91_PM_ULP0 0x01
-#define AT91_PM_ULP1 0x02
-#define AT91_PM_BACKUP 0x03
+#define AT91_PM_ULP0_FAST 0x02
+#define AT91_PM_ULP1 0x03
+#define AT91_PM_BACKUP 0x04
#ifndef __ASSEMBLY__
struct at91_pm_data {
diff --git a/arch/arm/mach-at91/pm_suspend.S b/arch/arm/mach-at91/pm_suspend.S
index be9764e8d3fa..0184de05c1be 100644
--- a/arch/arm/mach-at91/pm_suspend.S
+++ b/arch/arm/mach-at91/pm_suspend.S
@@ -164,7 +164,22 @@ ENDPROC(at91_backup_mode)
.macro at91_pm_ulp0_mode
ldr pmc, .pmc_base
+ ldr tmp2, .pm_mode
+ ldr tmp3, .mckr_offset
+
+ /* Check if ULP0 fast variant has been requested. */
+ cmp tmp2, #AT91_PM_ULP0_FAST
+ bne 0f
+
+ /* Set highest prescaler for power saving */
+ ldr tmp1, [pmc, tmp3]
+ bic tmp1, tmp1, #AT91_PMC_PRES
+ orr tmp1, tmp1, #AT91_PMC_PRES_64
+ str tmp1, [pmc, tmp3]
+ wait_mckrdy
+ b 1f
+0:
/* Turn off the crystal oscillator */
ldr tmp1, [pmc, #AT91_CKGR_MOR]
bic tmp1, tmp1, #AT91_PMC_MOSCEN
@@ -192,7 +207,18 @@ ENDPROC(at91_backup_mode)
/* Wait for interrupt */
1: at91_cpu_idle
- /* Restore RC oscillator state */
+ /* Check if ULP0 fast variant has been requested. */
+ cmp tmp2, #AT91_PM_ULP0_FAST
+ bne 5f
+
+ /* Set lowest prescaler for fast resume. */
+ ldr tmp1, [pmc, tmp3]
+ bic tmp1, tmp1, #AT91_PMC_PRES
+ str tmp1, [pmc, tmp3]
+ wait_mckrdy
+ b 6f
+
+5: /* Restore RC oscillator state */
ldr tmp1, .saved_osc_status
tst tmp1, #AT91_PMC_MOSCRCS
beq 4f
@@ -216,6 +242,7 @@ ENDPROC(at91_backup_mode)
str tmp1, [pmc, #AT91_CKGR_MOR]
wait_moscrdy
+6:
.endm
/**
@@ -473,23 +500,29 @@ ENDPROC(at91_backup_mode)
ENTRY(at91_ulp_mode)
ldr pmc, .pmc_base
ldr tmp2, .mckr_offset
+ ldr tmp3, .pm_mode
/* Save Master clock setting */
ldr tmp1, [pmc, tmp2]
str tmp1, .saved_mckr
/*
- * Set the Master clock source to slow clock
+ * Set master clock source to:
+ * - MAINCK if using ULP0 fast variant
+ * - slow clock, otherwise
*/
bic tmp1, tmp1, #AT91_PMC_CSS
+ cmp tmp3, #AT91_PM_ULP0_FAST
+ bne save_mck
+ orr tmp1, tmp1, #AT91_PMC_CSS_MAIN
+save_mck:
str tmp1, [pmc, tmp2]
wait_mckrdy
at91_plla_disable
- ldr r0, .pm_mode
- cmp r0, #AT91_PM_ULP1
+ cmp tmp3, #AT91_PM_ULP1
beq ulp1_mode
at91_pm_ulp0_mode
--
2.7.4
