link: Add charge_near_full state

Tell the host the battery is no longer charging when it hits 97%, and
set the power adapter LED to green.

This solves several problems:

1) The last 3% of charge takes a looong time.  Kernel/ACPI/UI already
have a hack to show the battery as charged when it's about 3% from
full, but the EC still showed a yellow LED.

2) If the system is charged and you briefly unplug the adapter, the
LED turned yellow for a long time as it slowly trickle-charged.  Now
it goes right to green.

3) A fully-charged battery will drop below 100% charge as it settles,
but won't accept more current at that time.  This caused the LED to
turn yellow and stay there until the battery finally settled down to
~96%, at which point it'd accept more current and top itself off.  The
whole time it did this, the kernel/ACPI/UI hack from (1) would keep
reporting "battery full".  Now the LED stays green too.

BUG=chrome-os-partner:11248
BRANCH=link
TEST=manual

- Discharge system to <95% full.
- Plug adapter in.  LED should come on yellow.
- At around 97% full, the LED should turn green.
- Around that the UI will display "battery full".
  (Note that due to rounding, the UI may take a few minutes to display
   "battery full" after the LED goes green; that's ok)
- Unplug and replug adapter.  LED should come on green.  UI still reports
  "battery full".

Change-Id: Ie56fbf3a05239e73d2c765bb98d36aa5cfedc2ef
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/34452

3 files changed, 44 insertions, 5 deletions

diff --git a/common/charge_state.c b/common/charge_state.c
index c1454996cb..b0deee1f2c 100644
--- a/common/charge_state.c
+++ b/common/charge_state.c
@@ -359,7 +359,11 @@ static enum power_state state_idle(struct power_state_context *ctx)
 				return PWR_STATE_ERROR;
 		}
 		update_charger_time(ctx, get_time());
-		return PWR_STATE_CHARGE;
+
+		if (ctx->curr.batt.state_of_charge < NEAR_FULL_THRESHOLD)
+			return PWR_STATE_CHARGE;
+		else
+			return PWR_STATE_CHARGE_NEAR_FULL;
 	}
 
 	return PWR_STATE_UNCHANGE;
@@ -602,6 +606,7 @@ void charge_state_machine_task(void)
 			break;
 		case PWR_STATE_IDLE0:
 			new_state = state_idle(ctx);
+			/* If still idling, move from IDLE0 to IDLE */
 			if (new_state == PWR_STATE_UNCHANGE)
 				new_state = PWR_STATE_IDLE;
 			break;
@@ -613,6 +618,22 @@ void charge_state_machine_task(void)
 			break;
 		case PWR_STATE_CHARGE:
 			new_state = state_charge(ctx);
+			if (new_state == PWR_STATE_UNCHANGE &&
+			    (ctx->curr.batt.state_of_charge >=
+			     NEAR_FULL_THRESHOLD)) {
+				/* Almost done charging */
+				new_state = PWR_STATE_CHARGE_NEAR_FULL;
+			}
+			break;
+
+		case PWR_STATE_CHARGE_NEAR_FULL:
+			new_state = state_charge(ctx);
+			if (new_state == PWR_STATE_UNCHANGE &&
+			    (ctx->curr.batt.state_of_charge <
+			     NEAR_FULL_THRESHOLD)) {
+				/* Battery below almost-full threshold. */
+				new_state = PWR_STATE_CHARGE;
+			}
 			break;
 		case PWR_STATE_ERROR:
 			new_state = state_error(ctx);
@@ -648,6 +669,13 @@ void charge_state_machine_task(void)
 			 */
 			sleep_usec = POLL_PERIOD_SHORT;
 			break;
+		case PWR_STATE_CHARGE_NEAR_FULL:
+			/*
+			 * Battery is almost charged.  The last few percent
+			 * take a loooong time, so fall through and look like
+			 * we're charged.  This mirrors similar hacks at the
+			 * ACPI/kernel/UI level.
+			 */
 		case PWR_STATE_IDLE:
 			batt_flags = *ctx->memmap_batt_flags;
 			batt_flags &= ~EC_BATT_FLAG_CHARGING;
@@ -659,7 +687,8 @@ void charge_state_machine_task(void)
 			rv_setled = powerled_set(POWERLED_GREEN);
 			last_setled_time = get_time().val;
 
-			sleep_usec = POLL_PERIOD_LONG;
+			sleep_usec = (new_state == PWR_STATE_IDLE ?
+				      POLL_PERIOD_LONG : POLL_PERIOD_CHARGE);
 			break;
 		case PWR_STATE_DISCHARGE:
 			batt_flags = *ctx->memmap_batt_flags;
diff --git a/include/battery.h b/include/battery.h
index f647a29bc0..02001b763a 100644
--- a/include/battery.h
+++ b/include/battery.h
@@ -16,8 +16,8 @@
 
 /* Stop charge when state of charge reaches this percentage */
 #define STOP_CHARGE_THRESHOLD 100
-/* Threshold for power led to turn green */
-#define POWERLED_GREEN_THRESHOLD 90
+/* Tell host we're charged at this percentage */
+#define NEAR_FULL_THRESHOLD 97
 /* Precharge only when state of charge is below this level */
 #define PRE_CHARGE_THRESHOLD 25
 
diff --git a/include/charge_state.h b/include/charge_state.h
index 9b4e6d364f..d3b310607e 100644
--- a/include/charge_state.h
+++ b/include/charge_state.h
@@ -48,19 +48,28 @@
 
 /* Power states */
 enum power_state {
+	/* Meta-state; unchanged from previous time through task loop */
 	PWR_STATE_UNCHANGE = 0,
+	/* (Re-)initalizing charge state machine */
 	PWR_STATE_INIT,
+	/* Just transitioned from init to idle */
 	PWR_STATE_IDLE0,
+	/* Idle; AC present */
 	PWR_STATE_IDLE,
+	/* Discharging */
 	PWR_STATE_DISCHARGE,
+	/* Charging */
 	PWR_STATE_CHARGE,
+	/* Charging, almost fully charged */
+	PWR_STATE_CHARGE_NEAR_FULL,
+	/* Charging state machine error */
 	PWR_STATE_ERROR
 };
 
 /* Debugging constants, in the same order as enum power_state. This string
  * table was moved here to sync with enum above.
  */
-#define POWER_STATE_NAME_TABLE \
+#define POWER_STATE_NAME_TABLE  \
 	{			\
 		"unchange",	\
 		"init",		\
@@ -68,6 +77,7 @@ enum power_state {
 		"idle",		\
 		"discharge",	\
 		"charge",	\
+		"charge_near_full",      \
 		"error"		\
 	}
 	/* End of POWER_STATE_NAME_TABLE macro */