nuc: Add support for CONFIG_LOW_POWER_S0.

To get better power consumption in S0, we add FW support for
CONFIG_LOW_POWER_S0.

Before entering deep idle in S0, we must enable Host interrupt to wake up
EC if it needs to service LPC bus.

This version also add a new bit of sleep_mask (SLEEP_MASK_FAN) in system.h
to prevent EC enter deep idle if fan's duty isn't zero. Normally, the freq of
PWM fan is 25 kHz. It means we must select apb2 clock as the source clock of
PWM fan. Or fan would stop when ec enters deep idle because of no PWM signal.

In hwtimer.c, we reset the preload counter to maximum value in ITEI32's ISR
since preload counter is changed by __hw_clock_source_set all the time.
We also found there're no event set if it's deadline is over 32 bits but
current source clock isn't. To prevent ec doesn't wake-up in deep-idle even if
ITIM32 expires, FW set an event for ITIM32 after process_timers().

Modified sources:
1. wheatley/board.h: Add CONFIG_LOW_POWER_S0 definition.
2. clock.c: Enable Host interrupt for LPC.
3. clock.c: Disable LP_WK_CTL for better power consumption.
4. gpio.c: Add ISR for Host interrupt.
5. uart.c: Introduce bit 6 of USTAT to make sure transmitting is completed.
6. register.h: Add uart_clear_pending_wakeup function.
7. hwtimer.c: Fixed watchdog issue when ITIM32 is closed to overflow.
8. fan.c: Enable deep sleep if duty cycle is zero.
9. include/system.h: Add SLEEP_MASK_FAN for fan control loop.
10. core/cortex-m/task.c: Add "isb" to flash the garbage data in the
    instruction pipeline.

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

Change-Id: Ibe3630d0d68cf3f32206adb2afa1b5958916a2be
Signed-off-by: Mulin Chao <mlchao@nuvoton.com>
Reviewed-on: https://chromium-review.googlesource.com/324651
Reviewed-by: Shawn N <shawnn@chromium.org>

1 files changed, 52 insertions, 24 deletions

diff --git a/chip/npcx/hwtimer.c b/chip/npcx/hwtimer.c
index 88809c01a0..5a7fa8b38c 100644
--- a/chip/npcx/hwtimer.c
+++ b/chip/npcx/hwtimer.c
@@ -13,11 +13,14 @@
 #include "hwtimer_chip.h"
 #include "math_util.h"
 #include "registers.h"
+#include "console.h"
 #include "task.h"
 #include "timer.h"
 
 /* Use ITIM32 as main hardware timer */
 #define TICK_ITIM32_MAX_CNT  0xFFFFFFFF
+/* Maximum deadline of event */
+#define EVT_MAX_EXPIRED_US   0xFFFFFFFF
 
 /* Depth of event timer */
 #define TICK_EVT_DEPTH         16 /* Depth of event timer Unit: bits */
@@ -105,21 +108,24 @@ void __hw_clock_event_set(uint32_t deadline)
 /* Returns the time-stamp of the next programmed event */
 uint32_t __hw_clock_event_get(void)
 {
-	return evt_expired_us;
+	if (evt_expired_us)
+		return evt_expired_us;
+	else /* No events. Give maximum deadline */
+		return EVT_MAX_EXPIRED_US;
 }
 
 /* Get current counter value of event timer */
-uint32_t __hw_clock_event_count(void)
+uint16_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(uint32_t pre_evt_cnt)
+uint32_t __hw_clock_get_sleep_time(uint16_t pre_evt_cnt)
 {
 	fp_t evt_tick = FLOAT_TO_FP(SECOND/(float)INT_32K_CLOCK);
 	uint32_t sleep_time;
-	uint32_t cnt = NPCX_ITCNT16(ITIM_EVENT_NO);
+	uint16_t cnt = NPCX_ITCNT16(ITIM_EVENT_NO);
 
 	/* Event has been triggered but timer ISR dosen't handle it */
 	if (IS_BIT_SET(NPCX_ITCTS(ITIM_EVENT_NO), NPCX_ITCTS_TO_STS))
@@ -149,21 +155,33 @@ void __hw_clock_event_clear(void)
 /* Irq for hwtimer event */
 void __hw_clock_event_irq(void)
 {
-	/* Clear timeout status for event */
-	SET_BIT(NPCX_ITCTS(ITIM_EVENT_NO), NPCX_ITCTS_TO_STS);
-
 	/* ITIM event module disable */
 	CLEAR_BIT(NPCX_ITCTS(ITIM_EVENT_NO), NPCX_ITCTS_ITEN);
 
 	/* Disable interrupt of event */
 	task_disable_irq(ITIM16_INT(ITIM_EVENT_NO));
 
+	/* Clear timeout status for event */
+	SET_BIT(NPCX_ITCTS(ITIM_EVENT_NO), NPCX_ITCTS_TO_STS);
+
 	/* Clear event parameters */
 	evt_expired_us = 0;
 	evt_cnt = 0;
 
 	/* handle upper driver */
 	process_timers(0);
+
+#ifdef CONFIG_LOW_POWER_IDLE
+	/*
+	 * Set event for ITIM32 after process_timers() since no events set if
+	 * event's deadline is over 32 bits but current source clock isn't.
+	 * ITIM32 is based on apb2 and ec won't wake-up in deep-idle even if it
+	 * expires.
+	 */
+	if (evt_expired_us == 0)
+		__hw_clock_event_set(EVT_MAX_EXPIRED_US);
+#endif
+
 }
 DECLARE_IRQ(ITIM16_INT(ITIM_EVENT_NO) , __hw_clock_event_irq, 1);
 
@@ -171,6 +189,23 @@ DECLARE_IRQ(ITIM16_INT(ITIM_EVENT_NO) , __hw_clock_event_irq, 1);
 /*****************************************************************************/
 /* HWTimer tick handlers */
 
+/* Modify preload counter of source clock. */
+void hw_clock_source_set_preload(uint32_t ts, uint8_t clear)
+{
+	/* ITIM32 module disable */
+	CLEAR_BIT(NPCX_ITCTS(ITIM32), NPCX_ITCTS_ITEN);
+
+	CLEAR_BIT(NPCX_ITCTS(ITIM32), NPCX_ITCTS_CKSEL);
+
+	/* Set preload counter to current time */
+	NPCX_ITCNT32 = TICK_ITIM32_MAX_CNT - ts;
+	/* Clear timeout status or not */
+	if (clear)
+		SET_BIT(NPCX_ITCTS(ITIM32), NPCX_ITCTS_TO_STS);
+	/* ITIM32 module enable */
+	SET_BIT(NPCX_ITCTS(ITIM32), NPCX_ITCTS_ITEN);
+}
+
 /* Returns the value of the free-running counter used as clock. */
 uint32_t __hw_clock_source_read(void)
 {
@@ -187,13 +222,7 @@ void __hw_clock_source_set(uint32_t ts)
 #if DEBUG_TMR
 	cur_cnt_us_dbg = TICK_ITIM32_MAX_CNT - ts;
 #endif
-	/* ITIM32 module disable */
-	CLEAR_BIT(NPCX_ITCTS(ITIM32), NPCX_ITCTS_ITEN);
-	/* Set current time */
-	NPCX_ITCNT32 = TICK_ITIM32_MAX_CNT - ts;
-	/* ITIM32 module enable */
-	SET_BIT(NPCX_ITCTS(ITIM32), NPCX_ITCTS_ITEN);
-
+	hw_clock_source_set_preload(ts, 0);
 }
 
 /* Irq for hwtimer tick */
@@ -201,16 +230,21 @@ void __hw_clock_source_irq(void)
 {
 	/* Is timeout trigger trigger? */
 	if (IS_BIT_SET(NPCX_ITCTS(ITIM32), NPCX_ITCTS_TO_STS)) {
-		/* Clear timeout status*/
-		SET_BIT(NPCX_ITCTS(ITIM32), NPCX_ITCTS_TO_STS);
+		/* Restore ITIM32 preload counter value to maximum value */
+		hw_clock_source_set_preload(0, 1);
 		/* 32-bits timer count overflow */
 		process_timers(1);
 
 	} else { /* Handle soft trigger */
 		process_timers(0);
+#ifdef CONFIG_LOW_POWER_IDLE
+		/* Set event for ITIM32. Please see above for detail */
+		if (evt_expired_us == 0)
+			__hw_clock_event_set(EVT_MAX_EXPIRED_US);
+#endif
 	}
 }
-DECLARE_IRQ(NPCX_IRQ_ITIM32, __hw_clock_source_irq, 1);
+DECLARE_IRQ(NPCX_IRQ_ITIM32, __hw_clock_source_irq, 0);
 
 static void update_prescaler(void)
 {
@@ -244,17 +278,11 @@ int __hw_clock_source_init(uint32_t start_t)
 	/* Set initial prescaler */
 	update_prescaler();
 
-	/* ITIM count down : TICK_ITIM32_MAX_CNT us expired */
-	NPCX_ITCNT32 = TICK_ITIM32_MAX_CNT;
-
 	/*
 	 * Override the count with the start value now that counting has
 	 * started.
 	 */
-	__hw_clock_source_set(start_t);
-
-	/* ITIM module enable */
-	SET_BIT(NPCX_ITCTS(ITIM32), NPCX_ITCTS_ITEN);
+	hw_clock_source_set_preload(start_t, 1);
 
 	/* Enable interrupt of ITIM */
 	task_enable_irq(NPCX_IRQ_ITIM32);