power: supply: bq25890: Add support to skip reset at probe() / remove()

On most x86/ACPI devices the firmware already fully initializes
the bq25890 charger at boot, in this case it is best to not reset
it at probe() time.

At support for a new "linux,skip-reset" boolean property to support this.
So far this new property is only used on x86/ACPI (non devicetree) devs,
IOW it is not used in actual devicetree files. The devicetree-bindings
maintainers have requested properties like these to not be added to the
devicetree-bindings, so the new property is deliberately not added
to the existing devicetree-bindings.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/bq25890_charger.c

@@ -110,6 +110,7 @@ struct bq25890_device {
 	struct regmap *rmap;
 	struct regmap_field *rmap_fields[F_MAX_FIELDS];
 
+	bool skip_reset;
 	enum bq25890_chip_version chip_version;
 	struct bq25890_init_data init_data;
 	struct bq25890_state state;
@@ -739,10 +740,12 @@ static int bq25890_hw_init(struct bq25890_device *bq)
 {
 	int ret;
 
-	ret = bq25890_chip_reset(bq);
-	if (ret < 0) {
-		dev_dbg(bq->dev, "Reset failed %d\n", ret);
-		return ret;
+	if (!bq->skip_reset) {
+		ret = bq25890_chip_reset(bq);
+		if (ret < 0) {
+			dev_dbg(bq->dev, "Reset failed %d\n", ret);
+			return ret;
+		}
 	}
 
 	/* disable watchdog */
@@ -977,6 +980,8 @@ static int bq25890_fw_probe(struct bq25890_device *bq)
 	int ret;
 	struct bq25890_init_data *init = &bq->init_data;
 
+	bq->skip_reset = device_property_read_bool(bq->dev, "linux,skip-reset");
+
 	ret = bq25890_fw_read_u32_props(bq);
 	if (ret < 0)
 		return ret;
@@ -1089,8 +1094,10 @@ static int bq25890_remove(struct i2c_client *client)
 	if (!IS_ERR_OR_NULL(bq->usb_phy))
 		usb_unregister_notifier(bq->usb_phy, &bq->usb_nb);
 
-	/* reset all registers to default values */
-	bq25890_chip_reset(bq);
+	if (!bq->skip_reset) {
+		/* reset all registers to default values */
+		bq25890_chip_reset(bq);
+	}
 
 	return 0;
 }