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From:   Alistair Francis <alistair@alistair23.me>
To:     dmitry.torokhov@gmail.com, linux-input@vger.kernel.org,
        linux-imx@nxp.com, kernel@pengutronix.de, pinglinux@gmail.com,
        tatsunosuke.tobita@wacom.com, junkpainting@gmail.com,
        ping.cheng@wacom.com
Cc:     linux-kernel@vger.kernel.org, alistair23@gmail.com,
        robh+dt@kernel.org, devicetree@vger.kernel.org,
        Alistair Francis <alistair@alistair23.me>
Subject: [PATCH] Input: wacom_i2c - Allow flipping the values from the DT
Date:   Sun, 29 Aug 2021 19:19:14 +1000
Message-Id: <20210829091925.190-3-alistair@alistair23.me>
In-Reply-To: <20210829091925.190-1-alistair@alistair23.me>
References: <20210829091925.190-1-alistair@alistair23.me>
MIME-Version: 1.0
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Allow the device tree properties to flip the tilx, position or distance
values.

This is required for the stylus to work correctly on the reMarkable 2.

Signed-off-by: Alistair Francis <alistair@alistair23.me>
---
 .../input/touchscreen/wacom,generic.yaml      | 20 +++++++++++
 drivers/input/touchscreen/wacom_i2c.c         | 36 +++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/wacom,generic.yaml b/Documentation/devicetree/bindings/input/touchscreen/wacom,generic.yaml
index a8a7f362b0ce..d451c9a235b6 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/wacom,generic.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/wacom,generic.yaml
@@ -25,6 +25,26 @@ properties:
   vdd-supply:
     description: Power Supply
 
+  flip-tilt-x:
+    type: boolean
+    description: Flip the tilt X values read from device
+
+  flip-tilt-y:
+    type: boolean
+    description: Flip the tilt Y values read from device
+
+  flip-pos-x:
+    type: boolean
+    description: Flip the X position values read from device
+
+  flip-pos-y:
+    type: boolean
+    description: Flip the Y position values read from device
+
+  flip-distance:
+    type: boolean
+    description: Flip the distance values read from device
+
 required:
   - compatible
   - reg
diff --git a/drivers/input/touchscreen/wacom_i2c.c b/drivers/input/touchscreen/wacom_i2c.c
index f78a43212901..903353106ca8 100644
--- a/drivers/input/touchscreen/wacom_i2c.c
+++ b/drivers/input/touchscreen/wacom_i2c.c
@@ -105,6 +105,12 @@ struct wacom_i2c {
 	u8 data[WACOM_QUERY_SIZE];
 	bool prox;
 	int tool;
+
+	bool flip_tilt_x;
+	bool flip_tilt_y;
+	bool flip_pos_x;
+	bool flip_pos_y;
+	bool flip_distance;
 };
 
 static int wacom_query_device(struct i2c_client *client,
@@ -198,6 +204,19 @@ static int wacom_query_device(struct i2c_client *client,
 	return 0;
 }
 
+#ifdef CONFIG_OF
+static void wacom_of_read(struct wacom_i2c *wac_i2c)
+{
+	struct i2c_client *client = wac_i2c->client;
+
+	wac_i2c->flip_tilt_x = of_property_read_bool(client->dev.of_node, "flip-tilt-x");
+	wac_i2c->flip_tilt_y = of_property_read_bool(client->dev.of_node, "flip-tilt-y");
+	wac_i2c->flip_pos_x = of_property_read_bool(client->dev.of_node, "flip-pos-x");
+	wac_i2c->flip_pos_y = of_property_read_bool(client->dev.of_node, "flip-pos-y");
+	wac_i2c->flip_distance = of_property_read_bool(client->dev.of_node, "flip-distance");
+}
+#endif
+
 static irqreturn_t wacom_i2c_irq(int irq, void *dev_id)
 {
 	struct wacom_i2c *wac_i2c = dev_id;
@@ -234,6 +253,13 @@ static irqreturn_t wacom_i2c_irq(int irq, void *dev_id)
 
 	wac_i2c->prox = data[3] & 0x20;
 
+	// Flip the values based on properties from the device tree
+	distance = wac_i2c->flip_distance ? -distance : distance;
+	x = wac_i2c->flip_pos_x ? (features->x_max - x) : x;
+	y = wac_i2c->flip_pos_y ? (features->y_max - y) : y;
+	tilt_x = wac_i2c->flip_tilt_x ? -tilt_x : tilt_x;
+	tilt_y = wac_i2c->flip_tilt_y ? -tilt_y : tilt_y;
+
 	touchscreen_report_pos(input, &wac_i2c->props, features->x_max,
 			       features->y_max, true);
 	input_report_key(input, BTN_TOUCH, tsw || ers);
@@ -361,6 +387,16 @@ static int wacom_i2c_probe(struct i2c_client *client,
 		return error;
 	}
 
+#ifdef CONFIG_OF
+	wacom_of_read(wac_i2c);
+#else
+	wac_i2c->flip_tilt_x = false;
+	wac_i2c->flip_tilt_y = false;
+	wac_i2c->flip_pos_x = false;
+	wac_i2c->flip_pos_y = false;
+	wac_i2c->flip_distance = false;
+#endif
+
 	return 0;
 }
 
-- 
2.31.1