power: supply: ab8500: Swap max and overvoltage

We should terminate charging when we reach the voltage_max_design_uv
not overvoltage_limit_uv, this is an abuse of that struct member.

The overvoltage limit is actually not configurable on the AB8500,
it is fixed to 4.75 V so drop a comment about that in the code.

Fixes: 2a5f4183 ("power: supply: ab8500: Standardize voltages")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/ab8500_bmdata.c

@@ -186,13 +186,11 @@ int ab8500_bm_of_probe(struct power_supply *psy,
 	 * fall back to safe defaults.
 	 */
 	if ((bi->voltage_min_design_uv < 0) ||
-	    (bi->voltage_max_design_uv < 0) ||
-	    (bi->overvoltage_limit_uv < 0)) {
+	    (bi->voltage_max_design_uv < 0)) {
 		/* Nominal voltage is 3.7V for unknown batteries */
 		bi->voltage_min_design_uv = 3700000;
-		bi->voltage_max_design_uv = 3700000;
-		/* Termination voltage (overcharge limit) 4.05V */
-		bi->overvoltage_limit_uv = 4050000;
+		/* Termination voltage 4.05V */
+		bi->voltage_max_design_uv = 4050000;
 	}
 
 	if (bi->constant_charge_current_max_ua < 0)

drivers/power/supply/ab8500_chargalg.c

@@ -802,7 +802,7 @@ static void ab8500_chargalg_end_of_charge(struct ab8500_chargalg *di)
 	if (di->charge_status == POWER_SUPPLY_STATUS_CHARGING &&
 		di->charge_state == STATE_NORMAL &&
 		!di->maintenance_chg && (di->batt_data.volt_uv >=
-		di->bm->bi->overvoltage_limit_uv ||
+		di->bm->bi->voltage_max_design_uv ||
 		di->events.usb_cv_active || di->events.ac_cv_active) &&
 		di->batt_data.avg_curr_ua <
 		di->bm->bi->charge_term_current_ua &&

drivers/power/supply/ab8500_fg.c

@@ -2263,7 +2263,13 @@ static int ab8500_fg_init_hw_registers(struct ab8500_fg *di)
 {
 	int ret;
 
-	/* Set VBAT OVV threshold */
+	/*
+	 * Set VBAT OVV (overvoltage) threshold to 4.75V (typ) this is what
+	 * the hardware supports, nothing else can be configured in hardware.
+	 * See this as an "outer limit" where the charger will certainly
+	 * shut down. Other (lower) overvoltage levels need to be implemented
+	 * in software.
+	 */
 	ret = abx500_mask_and_set_register_interruptible(di->dev,
 		AB8500_CHARGER,
 		AB8500_BATT_OVV,