Input: atmel_mxt_ts - switch from OF to generic device properties

Instead of using OF-specific APIs to fecth device properties, let's switch
to generic device properties API. This will allow us to use device
properties on legacy ChromeOS devices and get rid of platform data down
the road.
Acked-by: Nick Dyer <nick@shmanahar.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Benson Leung <bleung@chromium.org>

drivers/input/touchscreen/atmel_mxt_ts.c

@@ -29,6 +29,7 @@
 #include <linux/of.h>
 #include <linux/slab.h>
 #include <linux/gpio/consumer.h>
+#include <linux/property.h>
 #include <asm/unaligned.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ioctl.h>
@@ -2922,47 +2923,52 @@ static void mxt_input_close(struct input_dev *dev)
 	mxt_stop(data);
 }
 
-#ifdef CONFIG_OF
-static const struct mxt_platform_data *mxt_parse_dt(struct i2c_client *client)
+static const struct mxt_platform_data *
+mxt_parse_device_properties(struct i2c_client *client)
 {
+	static const char keymap_property[] = "linux,gpio-keymap";
 	struct mxt_platform_data *pdata;
-	struct device_node *np = client->dev.of_node;
 	u32 *keymap;
-	int proplen, ret;
-
-	if (!np)
-		return ERR_PTR(-ENOENT);
+	int n_keys;
+	int error;
 
 	pdata = devm_kzalloc(&client->dev, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)
 		return ERR_PTR(-ENOMEM);
 
-	if (of_find_property(np, "linux,gpio-keymap", &proplen)) {
-		pdata->t19_num_keys = proplen / sizeof(u32);
+	if (device_property_present(&client->dev, keymap_property)) {
+		n_keys = device_property_read_u32_array(&client->dev,
+							keymap_property,
+							NULL, 0);
+		if (n_keys <= 0) {
+			error = n_keys < 0 ? n_keys : -EINVAL;
+			dev_err(&client->dev,
+				"invalid/malformed '%s' property: %d\n",
+				keymap_property, error);
+			return ERR_PTR(error);
+		}
 
-		keymap = devm_kzalloc(&client->dev,
-				pdata->t19_num_keys * sizeof(keymap[0]),
+		keymap = devm_kmalloc_array(&client->dev, n_keys, sizeof(u32),
 					    GFP_KERNEL);
 		if (!keymap)
 			return ERR_PTR(-ENOMEM);
 
-		ret = of_property_read_u32_array(np, "linux,gpio-keymap",
-						 keymap, pdata->t19_num_keys);
-		if (ret)
-			dev_warn(&client->dev,
-				 "Couldn't read linux,gpio-keymap: %d\n", ret);
+		error = device_property_read_u32_array(&client->dev,
+						       keymap_property,
+						       keymap, n_keys);
+		if (error) {
+			dev_err(&client->dev,
+				"failed to parse '%s' property: %d\n",
+				keymap_property, error);
+			return ERR_PTR(error);
+		}
 
 		pdata->t19_keymap = keymap;
+		pdata->t19_num_keys = n_keys;
 	}
 
 	return pdata;
 }
-#else
-static const struct mxt_platform_data *mxt_parse_dt(struct i2c_client *client)
-{
-	return ERR_PTR(-ENOENT);
-}
-#endif
 
 #ifdef CONFIG_ACPI
 
@@ -3096,16 +3102,11 @@ mxt_get_platform_data(struct i2c_client *client)
 	if (pdata)
 		return pdata;
 
-	pdata = mxt_parse_dt(client);
-	if (!IS_ERR(pdata) || PTR_ERR(pdata) != -ENOENT)
-		return pdata;
-
 	pdata = mxt_parse_acpi(client);
 	if (!IS_ERR(pdata) || PTR_ERR(pdata) != -ENOENT)
 		return pdata;
 
-	dev_err(&client->dev, "No platform data specified\n");
-	return ERR_PTR(-EINVAL);
+	return mxt_parse_device_properties(client);
 }
 
 static const struct dmi_system_id chromebook_T9_suspend_dmi[] = {