ds2760_battery: add current_accum module parameter

When connecting a ds2760 to a partly loaded battery the first time,
there must be a way to bootstrap the current_accum value. Without that,
the current capactity value is bogus until the battery is fully charged
for the first time.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
Cc: Matt Reimer <mreimer@vpop.net>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

drivers/power/ds2760_battery.c

@@ -70,6 +70,10 @@ static unsigned int rated_capacity;
 module_param(rated_capacity, uint, 0644);
 MODULE_PARM_DESC(rated_capacity, "rated battery capacity, 10*mAh or index");
 
+static unsigned int current_accum;
+module_param(current_accum, uint, 0644);
+MODULE_PARM_DESC(current_accum, "current accumulator value");
+
 /* Some batteries have their rated capacity stored a N * 10 mAh, while
  * others use an index into this table. */
 static int rated_capacities[] = {
@@ -215,6 +219,22 @@ static int ds2760_battery_read_status(struct ds2760_device_info *di)
 	return 0;
 }
 
+static void ds2760_battery_set_current_accum(struct ds2760_device_info *di,
+					     unsigned int acr_val)
+{
+	unsigned char acr[2];
+
+	/* acr is in units of 0.25 mAh */
+	acr_val *= 4L;
+	acr_val /= 1000;
+
+	acr[0] = acr_val >> 8;
+	acr[1] = acr_val & 0xff;
+
+	if (w1_ds2760_write(di->w1_dev, acr, DS2760_CURRENT_ACCUM_MSB, 2) < 2)
+		dev_warn(di->dev, "ACR write failed\n");
+}
+
 static void ds2760_battery_update_status(struct ds2760_device_info *di)
 {
 	int old_charge_status = di->charge_status;
@@ -246,21 +266,9 @@ static void ds2760_battery_update_status(struct ds2760_device_info *di)
 			if (di->full_counter < 2) {
 				di->charge_status = POWER_SUPPLY_STATUS_CHARGING;
 			} else {
-				unsigned char acr[2];
-				int acr_val;
-
-				/* acr is in units of 0.25 mAh */
-				acr_val = di->full_active_uAh * 4L / 1000;
-
-				acr[0] = acr_val >> 8;
-				acr[1] = acr_val & 0xff;
-
-				if (w1_ds2760_write(di->w1_dev, acr,
-				    DS2760_CURRENT_ACCUM_MSB, 2) < 2)
-					dev_warn(di->dev,
-						 "ACR reset failed\n");
-
 				di->charge_status = POWER_SUPPLY_STATUS_FULL;
+				ds2760_battery_set_current_accum(di,
+						di->full_active_uAh);
 			}
 		}
 	} else {
@@ -423,6 +431,11 @@ static int ds2760_battery_probe(struct platform_device *pdev)
 	if (rated_capacity)
 		ds2760_battery_write_rated_capacity(di, rated_capacity);
 
+	/* set current accumulator if given as parameter.
+	 * this should only be done for bootstrapping the value */
+	if (current_accum)
+		ds2760_battery_set_current_accum(di, current_accum);
+
 	retval = power_supply_register(&pdev->dev, &di->bat);
 	if (retval) {
 		dev_err(di->dev, "failed to register battery\n");