HID: i2c-hid: Allow ACPI systems to specify "post-power-on-delay-ms"

The property "post-power-on-delay-ms" allows a platform to specify
the delay needed after power-on, but only via device trees currently.
Use device_property_* instead of of_* reads to allow ACPI systems to
also provide the same information. This is useful for Wacom hardware
on ACPI systems.
Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Documentation/devicetree/bindings/input/hid-over-i2c.txt

@@ -31,7 +31,7 @@ device-specific compatible properties, which should be used in addition to the
 
 - vdd-supply: phandle of the regulator that provides the supply voltage.
 - post-power-on-delay-ms: time required by the device after enabling its regulators
-  before it is ready for communication. Must be used with 'vdd-supply'.
+  or powering it on, before it is ready for communication.
 
 Example:
 

drivers/hid/i2c-hid/i2c-hid.c

@@ -934,11 +934,6 @@ static int i2c_hid_of_probe(struct i2c_client *client,
 	}
 	pdata->hid_descriptor_address = val;
 
-	ret = of_property_read_u32(dev->of_node, "post-power-on-delay-ms",
-				   &val);
-	if (!ret)
-		pdata->post_power_delay_ms = val;
-
 	return 0;
 }
 
@@ -955,6 +950,16 @@ static inline int i2c_hid_of_probe(struct i2c_client *client,
 }
 #endif
 
+static void i2c_hid_fwnode_probe(struct i2c_client *client,
+				 struct i2c_hid_platform_data *pdata)
+{
+	u32 val;
+
+	if (!device_property_read_u32(&client->dev, "post-power-on-delay-ms",
+				      &val))
+		pdata->post_power_delay_ms = val;
+}
+
 static int i2c_hid_probe(struct i2c_client *client,
 			 const struct i2c_device_id *dev_id)
 {
@@ -998,6 +1003,9 @@ static int i2c_hid_probe(struct i2c_client *client,
 		ihid->pdata = *platform_data;
 	}
 
+	/* Parse platform agnostic common properties from ACPI / device tree */
+	i2c_hid_fwnode_probe(client, &ihid->pdata);
+
 	ihid->pdata.supply = devm_regulator_get(&client->dev, "vdd");
 	if (IS_ERR(ihid->pdata.supply)) {
 		ret = PTR_ERR(ihid->pdata.supply);