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

1 files changed, 11 insertions, 1 deletions

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 */