ab8500_bm: Recharge condition not optimal for battery

Today the battery recharge is determined with a voltage threshold. This
voltage threshold is only valid when the battery is relaxed. In charging
algorithm the voltage read is the loaded battery voltage and no
compensation is done to get the relaxed voltage. When maintenance
charging is not selected, this makes the recharging condition to almost
immediately activate when there is a discharge present on the battery.

Depending on which vendor the battery comes from this behavior can wear
out the battery much faster than normal.

The fuelgauge driver is responsible to monitor the actual battery
capacity and is able to estimate the remaining capacity. It is better to
use the remaining capacity as a limit to determine when battery should
be recharged.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Marcus Cooper <marcus.xm.cooper@stericsson.com>
Reviewed-by: Hakan BERG <hakan.berg@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>

1 files changed, 135 insertions, 11 deletions

diff --git a/drivers/power/ab8500_fg.c b/drivers/power/ab8500_fg.c
index f3dbba8b3925..76fab6b5c541 100644
--- a/drivers/power/ab8500_fg.c
+++ b/drivers/power/ab8500_fg.c
@@ -113,6 +113,13 @@ struct ab8500_fg_avg_cap {
 	int sum;
 };
 
+struct ab8500_fg_cap_scaling {
+	bool enable;
+	int cap_to_scale[2];
+	int disable_cap_level;
+	int scaled_cap;
+};
+
 struct ab8500_fg_battery_capacity {
 	int max_mah_design;
 	int max_mah;
@@ -123,6 +130,7 @@ struct ab8500_fg_battery_capacity {
 	int prev_percent;
 	int prev_level;
 	int user_mah;
+	struct ab8500_fg_cap_scaling cap_scale;
 };
 
 struct ab8500_fg_flags {
@@ -1167,6 +1175,99 @@ static int ab8500_fg_capacity_level(struct ab8500_fg *di)
 }
 
 /**
+ * ab8500_fg_calculate_scaled_capacity() - Capacity scaling
+ * @di:		pointer to the ab8500_fg structure
+ *
+ * Calculates the capacity to be shown to upper layers. Scales the capacity
+ * to have 100% as a reference from the actual capacity upon removal of charger
+ * when charging is in maintenance mode.
+ */
+static int ab8500_fg_calculate_scaled_capacity(struct ab8500_fg *di)
+{
+	struct ab8500_fg_cap_scaling *cs = &di->bat_cap.cap_scale;
+	int capacity = di->bat_cap.prev_percent;
+
+	if (!cs->enable)
+		return capacity;
+
+	/*
+	 * As long as we are in fully charge mode scale the capacity
+	 * to show 100%.
+	 */
+	if (di->flags.fully_charged) {
+		cs->cap_to_scale[0] = 100;
+		cs->cap_to_scale[1] =
+			max(capacity, di->bm->fg_params->maint_thres);
+		dev_dbg(di->dev, "Scale cap with %d/%d\n",
+			 cs->cap_to_scale[0], cs->cap_to_scale[1]);
+	}
+
+	/* Calculates the scaled capacity. */
+	if ((cs->cap_to_scale[0] != cs->cap_to_scale[1])
+					&& (cs->cap_to_scale[1] > 0))
+		capacity = min(100,
+				 DIV_ROUND_CLOSEST(di->bat_cap.prev_percent *
+						 cs->cap_to_scale[0],
+						 cs->cap_to_scale[1]));
+
+	if (di->flags.charging) {
+		if (capacity < cs->disable_cap_level) {
+			cs->disable_cap_level = capacity;
+			dev_dbg(di->dev, "Cap to stop scale lowered %d%%\n",
+				cs->disable_cap_level);
+		} else if (!di->flags.fully_charged) {
+			if (di->bat_cap.prev_percent >=
+			    cs->disable_cap_level) {
+				dev_dbg(di->dev, "Disabling scaled capacity\n");
+				cs->enable = false;
+				capacity = di->bat_cap.prev_percent;
+			} else {
+				dev_dbg(di->dev,
+					"Waiting in cap to level %d%%\n",
+					cs->disable_cap_level);
+				capacity = cs->disable_cap_level;
+			}
+		}
+	}
+
+	return capacity;
+}
+
+/**
+ * ab8500_fg_update_cap_scalers() - Capacity scaling
+ * @di:		pointer to the ab8500_fg structure
+ *
+ * To be called when state change from charge<->discharge to update
+ * the capacity scalers.
+ */
+static void ab8500_fg_update_cap_scalers(struct ab8500_fg *di)
+{
+	struct ab8500_fg_cap_scaling *cs = &di->bat_cap.cap_scale;
+
+	if (!cs->enable)
+		return;
+	if (di->flags.charging) {
+		di->bat_cap.cap_scale.disable_cap_level =
+			di->bat_cap.cap_scale.scaled_cap;
+		dev_dbg(di->dev, "Cap to stop scale at charge %d%%\n",
+				di->bat_cap.cap_scale.disable_cap_level);
+	} else {
+		if (cs->scaled_cap != 100) {
+			cs->cap_to_scale[0] = cs->scaled_cap;
+			cs->cap_to_scale[1] = di->bat_cap.prev_percent;
+		} else {
+			cs->cap_to_scale[0] = 100;
+			cs->cap_to_scale[1] =
+				max(di->bat_cap.prev_percent,
+				    di->bm->fg_params->maint_thres);
+		}
+
+		dev_dbg(di->dev, "Cap to scale at discharge %d/%d\n",
+				cs->cap_to_scale[0], cs->cap_to_scale[1]);
+	}
+}
+
+/**
  * ab8500_fg_check_capacity_limits() - Check if capacity has changed
  * @di:		pointer to the ab8500_fg structure
  * @init:	capacity is allowed to go up in init mode
@@ -1214,16 +1315,24 @@ static void ab8500_fg_check_capacity_limits(struct ab8500_fg *di, bool init)
 	} else if (di->flags.fully_charged) {
 		/*
 		 * We report 100% if algorithm reported fully charged
-		 * unless capacity drops too much
+		 * and show 100% during maintenance charging (scaling).
 		 */
 		if (di->flags.force_full) {
 			di->bat_cap.prev_percent = di->bat_cap.permille / 10;
 			di->bat_cap.prev_mah = di->bat_cap.mah;
-		} else if (!di->flags.force_full &&
-			di->bat_cap.prev_percent !=
-			(di->bat_cap.permille) / 10 &&
-			(di->bat_cap.permille / 10) <
-			di->bm->fg_params->maint_thres) {
+
+			changed = true;
+
+			if (!di->bat_cap.cap_scale.enable &&
+						di->bm->capacity_scaling) {
+				di->bat_cap.cap_scale.enable = true;
+				di->bat_cap.cap_scale.cap_to_scale[0] = 100;
+				di->bat_cap.cap_scale.cap_to_scale[1] =
+						di->bat_cap.prev_percent;
+				di->bat_cap.cap_scale.disable_cap_level = 100;
+			}
+		} else if ( di->bat_cap.prev_percent !=
+			(di->bat_cap.permille) / 10) {
 			dev_dbg(di->dev,
 				"battery reported full "
 				"but capacity dropping: %d\n",
@@ -1272,6 +1381,14 @@ static void ab8500_fg_check_capacity_limits(struct ab8500_fg *di, bool init)
 	}
 
 	if (changed) {
+		if (di->bm->capacity_scaling) {
+			di->bat_cap.cap_scale.scaled_cap =
+				ab8500_fg_calculate_scaled_capacity(di);
+
+			dev_info(di->dev, "capacity=%d (%d)\n",
+				di->bat_cap.prev_percent,
+				di->bat_cap.cap_scale.scaled_cap);
+		}
 		power_supply_changed(&di->fg_psy);
 		if (di->flags.fully_charged && di->flags.force_full) {
 			dev_dbg(di->dev, "Battery full, notifying.\n");
@@ -1337,7 +1454,7 @@ static void ab8500_fg_algorithm_charging(struct ab8500_fg *di)
 		 * Read the FG and calculate the new capacity
 		 */
 		mutex_lock(&di->cc_lock);
-		if (!di->flags.conv_done) {
+		if (!di->flags.conv_done && !di->flags.force_full) {
 			/* Wasn't the CC IRQ that got us here */
 			mutex_unlock(&di->cc_lock);
 			dev_dbg(di->dev, "%s CC conv not done\n",
@@ -2027,7 +2144,9 @@ static int ab8500_fg_get_property(struct power_supply *psy,
 			val->intval = di->bat_cap.prev_mah;
 		break;
 	case POWER_SUPPLY_PROP_CAPACITY:
-		if (di->flags.batt_unknown && !di->bm->chg_unknown_bat &&
+		if (di->bm->capacity_scaling)
+			val->intval = di->bat_cap.cap_scale.scaled_cap;
+		else if (di->flags.batt_unknown && !di->bm->chg_unknown_bat &&
 				di->flags.batt_id_received)
 			val->intval = 100;
 		else
@@ -2091,6 +2210,8 @@ static int ab8500_fg_get_ext_psy_data(struct device *dev, void *data)
 						break;
 					di->flags.charging = false;
 					di->flags.fully_charged = false;
+					if (di->bm->capacity_scaling)
+						ab8500_fg_update_cap_scalers(di);
 					queue_work(di->fg_wq, &di->fg_work);
 					break;
 				case POWER_SUPPLY_STATUS_FULL:
@@ -2103,10 +2224,13 @@ static int ab8500_fg_get_ext_psy_data(struct device *dev, void *data)
 					queue_work(di->fg_wq, &di->fg_work);
 					break;
 				case POWER_SUPPLY_STATUS_CHARGING:
-					if (di->flags.charging)
+					if (di->flags.charging &&
+						!di->flags.fully_charged)
 						break;
 					di->flags.charging = true;
 					di->flags.fully_charged = false;
+					if (di->bm->capacity_scaling)
+						ab8500_fg_update_cap_scalers(di);
 					queue_work(di->fg_wq, &di->fg_work);
 					break;
 				};
@@ -2146,8 +2270,8 @@ static int ab8500_fg_get_ext_psy_data(struct device *dev, void *data)
 		case POWER_SUPPLY_PROP_TEMP:
 			switch (ext->type) {
 			case POWER_SUPPLY_TYPE_BATTERY:
-			    if (di->flags.batt_id_received)
-				di->bat_temp = ret.intval;
+				if (di->flags.batt_id_received)
+					di->bat_temp = ret.intval;
 				break;
 			default:
 				break;