Cleanly force battery to mAh mode when reading capacity

Smart batteries can report capacity in mAh or 10mW units.  We forced
the units to mAh in charge_state.c's main loop, but that doesn't
guarantee that they're actually set before the capacity is read.  It's
cleaner to check the capacity reporting mode when actually reading the
capacity.

BUG=chrome-os-partner:20881
BRANCH=none
TEST=battery command reports the same capacity data before/after change
     (on rambi, design=2940 mAh)

Change-Id: I4a4c80eaade72bb09627d5d65693c097e264a992
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/176154

5 files changed, 34 insertions, 87 deletions

diff --git a/common/battery.c b/common/battery.c
index 140b7d22c7..a8ece1d796 100644
--- a/common/battery.c
+++ b/common/battery.c
@@ -120,7 +120,6 @@ static void print_battery_info(void)
 {
 	int value;
 	int hour, minute;
-	const char *unit;
 
 	print_item_name("Serial:");
 	if (check_print_error(battery_serial_number(&value)))
@@ -134,24 +133,21 @@ static void print_battery_info(void)
 	if (check_print_error(battery_get_mode(&value)))
 		ccprintf("0x%04x\n", value);
 
-	battery_is_in_10mw_mode(&value);
-	unit = value ? "0 mW" : " mAh";
-
 	print_item_name("Abs charge:");
 	if (check_print_error(battery_state_of_charge_abs(&value)))
 		ccprintf("%d %%\n", value);
 
 	print_item_name("Remaining:");
 	if (check_print_error(battery_remaining_capacity(&value)))
-		ccprintf("%d%s\n", value, unit);
+		ccprintf("%d mAh\n", value);
 
 	print_item_name("Cap-full:");
 	if (check_print_error(battery_full_charge_capacity(&value)))
-		ccprintf("%d%s\n", value, unit);
+		ccprintf("%d mAh\n", value);
 
 	print_item_name("  Design:");
 	if (check_print_error(battery_design_capacity(&value)))
-		ccprintf("%d%s\n", value, unit);
+		ccprintf("%d mAh\n", value);
 
 	print_item_name("Time-full:");
 	if (check_print_error(battery_time_to_full(&value))) {
diff --git a/common/charge_state.c b/common/charge_state.c
index 8f93248c05..be07113a0d 100644
--- a/common/charge_state.c
+++ b/common/charge_state.c
@@ -361,14 +361,6 @@ static int state_common(struct power_state_context *ctx)
 	if (batt->desired_current > user_current_limit)
 		batt->desired_current = user_current_limit;
 
-	if (battery_is_in_10mw_mode(&d)) {
-		curr->error |= F_BATTERY_MODE;
-	} else if (d) {
-		/* Battery capacity mode was set to mW; reset it back to mAh */
-		if (battery_set_10mw_mode(0))
-			ctx->curr.error |= F_BATTERY_MODE;
-	}
-
 	if (fake_state_of_charge >= 0)
 		*ctx->memmap_batt_cap =
 			fake_state_of_charge *
diff --git a/driver/battery/bq27541.c b/driver/battery/bq27541.c
index 72ec30b6fd..43b669476b 100644
--- a/driver/battery/bq27541.c
+++ b/driver/battery/bq27541.c
@@ -179,19 +179,6 @@ int battery_status(int *status)
 	return EC_ERROR_UNIMPLEMENTED;
 }
 
-int battery_is_in_10mw_mode(int *val)
-{
-	/* Always using mAh unit */
-	*val = 0;
-	return EC_SUCCESS;
-}
-
-int battery_set_10mw_mode(int enabled)
-{
-	/* Not supported by this battery chip */
-	return EC_ERROR_INVAL;
-}
-
 void battery_get_params(struct batt_params *batt)
 {
 	int v;
diff --git a/driver/battery/smart.c b/driver/battery/smart.c
index 7feca24bda..8b2bd2f8e2 100644
--- a/driver/battery/smart.c
+++ b/driver/battery/smart.c
@@ -37,32 +37,23 @@ int battery_get_mode(int *mode)
 	return sb_read(SB_BATTERY_MODE, mode);
 }
 
-int battery_set_mode(int mode)
-{
-	return sb_write(SB_BATTERY_MODE, mode);
-}
-
-int battery_is_in_10mw_mode(int *ret)
-{
-	int val;
-	int rv = battery_get_mode(&val);
-	if (rv)
-		return rv;
-	*ret = val & MODE_CAPACITY;
-	return EC_SUCCESS;
-}
+/**
+ * Force battery to mAh mode (instead of 10mW mode) for reporting capacity.
+ *
+ * @return non-zero if error.
+ */
 
-int battery_set_10mw_mode(int enabled)
+static int battery_force_mah_mode(void)
 {
 	int val, rv;
 	rv = battery_get_mode(&val);
 	if (rv)
 		return rv;
-	if (enabled)
-		val |= MODE_CAPACITY;
-	else
-		val &= ~MODE_CAPACITY;
-	return battery_set_mode(val);
+
+	if (val & MODE_CAPACITY)
+		rv = sb_write(SB_BATTERY_MODE, val & ~MODE_CAPACITY);
+
+	return rv;
 }
 
 int battery_state_of_charge_abs(int *percent)
@@ -72,11 +63,19 @@ int battery_state_of_charge_abs(int *percent)
 
 int battery_remaining_capacity(int *capacity)
 {
+	int rv = battery_force_mah_mode();
+	if (rv)
+		return rv;
+
 	return sb_read(SB_REMAINING_CAPACITY, capacity);
 }
 
 int battery_full_charge_capacity(int *capacity)
 {
+	int rv = battery_force_mah_mode();
+	if (rv)
+		return rv;
+
 	return sb_read(SB_FULL_CHARGE_CAPACITY, capacity);
 }
 
@@ -107,11 +106,12 @@ int battery_cycle_count(int *count)
 	return sb_read(SB_CYCLE_COUNT, count);
 }
 
-/* Designed battery capacity
- * unit: mAh or 10mW depends on battery mode
- */
 int battery_design_capacity(int *capacity)
 {
+	int rv = battery_force_mah_mode();
+	if (rv)
+		return rv;
+
 	return sb_read(SB_DESIGN_CAPACITY, capacity);
 }
 
@@ -228,11 +228,13 @@ void battery_get_params(struct batt_params *batt)
 	if (sb_read(SB_VOLTAGE, &batt->voltage))
 		batt->flags |= BATT_FLAG_BAD_ANY | BATT_FLAG_BAD_VOLTAGE;
 
+	/* Ensure battery current is set to 0 if unable to read it */
 	v = 0;
+
 	if (sb_read(SB_CURRENT, &v))
 		batt->flags |= BATT_FLAG_BAD_ANY;
-	else
-		batt->current = (int16_t)v;
+
+	batt->current = (int16_t)v;
 
 	if (sb_read(SB_CHARGING_VOLTAGE, &batt->desired_voltage) ||
 	    sb_read(SB_CHARGING_CURRENT, &batt->desired_current))
diff --git a/include/battery.h b/include/battery.h
index cb2a5c32ef..522f3aa80a 100644
--- a/include/battery.h
+++ b/include/battery.h
@@ -113,39 +113,12 @@ int battery_is_connected(void);
  *
  * See MODE_* constants in battery_smart.h
  *
- * @param mode		Destination for current mode.
+ * @param mode         Destination for current mode.
  * @return non-zero if error.
  */
 int battery_get_mode(int *mode);
 
 /**
- * Set battery mode.
- *
- * See MODE_* constants in battery_smart.h
- *
- * @param mode		New mode.
- * @return non-zero if error.
- */
-int battery_set_mode(int mode);
-
-/**
- * Check if battery is reporting capacity in 10 mW units.
- *
- * @param val		Destination for capacity units; set zero if mAh or
- *			non-zero if 10 mW.
- * @return non-zero if error.
- */
-int battery_is_in_10mw_mode(int *val);
-
-/**
- * Set battery capacity units.
- *
- * @param enabled	Set mode to mAh (=0) or 10 mW (=1)
- * @return non-zero if error.
- */
-int battery_set_10mw_mode(int enabled);
-
-/**
  * Read nominal voltage battery is designed to supply.
  *
  * @param voltage	Destination for voltage in mW
@@ -164,8 +137,7 @@ int battery_state_of_charge_abs(int *percent);
 /**
  * Read battery remaining capacity.
  *
- * @param capacity	Destination for capacity; units are mAh or 10 mW,
- *			depending on battery_is_in_10mw_mode().
+ * @param capacity	Destination for capacity in mAh
  * @return non-zero if error.
  */
 int battery_remaining_capacity(int *capacity);
@@ -173,8 +145,7 @@ int battery_remaining_capacity(int *capacity);
 /**
  * Read battery full charge capacity.
  *
- * @param capacity	Destination for capacity; units are mAh or 10 mW,
- *			depending on battery_is_in_10mw_mode().
+ * @param capacity	Destination for capacity in mAh
  * @return non-zero if error.
  */
 int battery_full_charge_capacity(int *capacity);
@@ -182,8 +153,7 @@ int battery_full_charge_capacity(int *capacity);
 /**
  * Read the nominal capacity the battery is designed to supply when new.
  *
- * @param capacity	Destination for capacity; units are mAh or 10 mW,
- *			depending on battery_is_in_10mw_mode().
+ * @param capacity	Destination for capacity in mAh
  * @return non-zero if error.
  */
 int battery_design_capacity(int *capacity);