nuc: Get more accurate value of deep idle time.

We should consider the interval between the calling __hw_clock_event_set and
entering deep idle. In order to get more accurate value of deep idle time, FW
should record the time-stamp before entering deep idle and calculate the deep
idle time based on it.

Modified drivers:
1. hwtimer_chip.h: Add new function declarations for deep idle time caculation.
2. hwtimer.c: Add new functionsfor deep idle time caculation.
3. clock.c: Modified for calculating more accurate deep idle time.

BUG=chrome-os-partner:34346
TEST=make buildall -j; test nuvoton IC specific drivers
BRANCH=none

Change-Id: Id037c4dc3564659e4ad493f2fc3ffc5d06c18b06
Signed-off-by: Mulin Chao <mlchao@nuvoton.com>
Reviewed-on: https://chromium-review.googlesource.com/320071
Reviewed-by: Randall Spangler <rspangler@chromium.org>

3 files changed, 21 insertions, 8 deletions

diff --git a/chip/npcx/clock.c b/chip/npcx/clock.c
index 40ffa205dc..2dcd176c54 100644
--- a/chip/npcx/clock.c
+++ b/chip/npcx/clock.c
@@ -234,7 +234,7 @@ void __idle(void)
 #else
 
 	timestamp_t t0, t1;
-	uint32_t next_evt_us;
+	uint32_t next_evt_us, evt_count;
 
 	/*
 	 * Initialize console in use to true and specify the console expire
@@ -272,13 +272,17 @@ void __idle(void)
 			NPCX_PMCSR = IDLE_PARAMS;
 			/* UART-rx(console) become to GPIO (NONE INT mode) */
 			clock_uart2gpio();
+
+			/* Get current counter value of event timer */
+			evt_count = __hw_clock_event_count();
 			/* Enter deep idle */
 			asm("wfi");
+			/* Get time delay cause of deep idle */
+			next_evt_us = __hw_clock_get_sleep_time(evt_count);
+
 			/* GPIO back to UART-rx (console) */
 			clock_gpio2uart();
 
-			/* Get time delay cause of deep idle */
-			next_evt_us = __hw_clock_get_sleep_time();
 			/* Fast forward timer according to wake-up timer. */
 			t1.val = t0.val + next_evt_us;
 			/* Record time spent in deep sleep. */
diff --git a/chip/npcx/hwtimer.c b/chip/npcx/hwtimer.c
index 0971198c03..4f8ff03308 100644
--- a/chip/npcx/hwtimer.c
+++ b/chip/npcx/hwtimer.c
@@ -108,8 +108,14 @@ uint32_t __hw_clock_event_get(void)
 	return evt_expired_us;
 }
 
+/* Get current counter value of event timer */
+uint32_t __hw_clock_event_count(void)
+{
+	return NPCX_ITCNT16(ITIM_EVENT_NO);
+}
+
 /* Returns time delay cause of deep idle */
-uint32_t __hw_clock_get_sleep_time(void)
+uint32_t __hw_clock_get_sleep_time(uint32_t pre_evt_cnt)
 {
 	fp_t evt_tick = FLOAT_TO_FP(SECOND/(float)INT_32K_CLOCK);
 	uint32_t sleep_time;
@@ -118,10 +124,10 @@ uint32_t __hw_clock_get_sleep_time(void)
 	interrupt_disable();
 	/* Event has been triggered but timer ISR dosen't handle it */
 	if (IS_BIT_SET(NPCX_ITCTS(ITIM_EVENT_NO), NPCX_ITCTS_TO_STS))
-		sleep_time = FP_TO_INT((fp_inter_t)(evt_cnt+1) * evt_tick);
+		sleep_time = FP_TO_INT((fp_inter_t)(pre_evt_cnt+1) * evt_tick);
 	/* Event hasn't been triggered */
 	else
-		sleep_time = FP_TO_INT((fp_inter_t)(evt_cnt+1 - cnt) *
+		sleep_time = FP_TO_INT((fp_inter_t)(pre_evt_cnt+1 - cnt) *
 				       evt_tick);
 	interrupt_enable();
 
diff --git a/chip/npcx/hwtimer_chip.h b/chip/npcx/hwtimer_chip.h
index b529bce463..ac657a2a4b 100644
--- a/chip/npcx/hwtimer_chip.h
+++ b/chip/npcx/hwtimer_chip.h
@@ -21,7 +21,10 @@ enum ITIM_SOURCE_CLOCK_T {
 /* Initialize ITIM16 timer */
 void init_hw_timer(int itim_no, enum ITIM_SOURCE_CLOCK_T source);
 
-/* Returns time delay cause of deep idle */
-uint32_t __hw_clock_get_sleep_time(void);
+/* Returns the counter value of event timer */
+uint32_t __hw_clock_event_count(void);
+
+/* Returns time delay because of deep idle */
+uint32_t __hw_clock_get_sleep_time(uint32_t pre_evt_cnt);
 
 #endif /* __CROS_EC_HWTIMER_CHIP_H */