[PATCH v2 3/7] Input: synaptics-rmi4 - f12: use hardcoded values for aftermarket touch ICs

[Caleb Connolly <caleb.connolly@linaro.org>]

From: methanal <baclofen@tuta.io>

Some replacement displays include third-party touch ICs which are
devoid of register descriptors. Create a fake data register descriptor
for such ICs and provide hardcoded default values.

It isn't possible to reliably determine if the touch IC is original or
not, so these fallback values are offered as an alternative to the error
path when register descriptors aren't available.

Signed-off-by: methanal <baclofen@tuta.io>
[changes for readability / codeflow, checkpatch fixes]
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
---
 drivers/input/rmi4/rmi_f12.c | 117 +++++++++++++++++++++++++++++++++----------
 1 file changed, 91 insertions(+), 26 deletions(-)

diff --git a/drivers/input/rmi4/rmi_f12.c b/drivers/input/rmi4/rmi_f12.c
index 7e97944f7616..719ee3b42550 100644
--- a/drivers/input/rmi4/rmi_f12.c
+++ b/drivers/input/rmi4/rmi_f12.c
@@ -195,6 +195,41 @@ static void rmi_f12_process_objects(struct f12_data *f12, u8 *data1, int size)
 		rmi_2d_sensor_abs_report(sensor, &sensor->objs[i], i);
 }
 
+static void rmi_f12_set_hardcoded_desc(struct rmi_function *fn, struct f12_data *f12)
+{
+	struct rmi_2d_sensor *sensor = &f12->sensor;
+	struct rmi_register_desc_item *reg_desc;
+
+	/* We have no f12->data_reg_desc, so the pkt_size is 0, override it with
+	 * a somewhat sensible default (this corresponds to 10 fingers).
+	 */
+	sensor->pkt_size = 88;
+
+	/*
+	 * There are no register descriptors to get these values from.
+	 * We set them to high values to either be overwritten by the clip
+	 * properties from devicetree, or to just not get in the way.
+	 */
+	sensor->max_x = 65535;
+	sensor->max_y = 65535;
+
+	/*
+	 * Create the Data1 register descriptor so that touch events
+	 * can work properly.
+	 */
+	reg_desc = devm_kcalloc(&fn->dev, 1,
+			sizeof(struct rmi_register_desc_item), GFP_KERNEL);
+	reg_desc->reg = 1;
+	reg_desc->reg_size = 80;
+	reg_desc->num_subpackets = 10;
+
+	f12->data1 = reg_desc;
+	f12->data1_offset = 0;
+	sensor->nbr_fingers = reg_desc->num_subpackets;
+	sensor->report_abs = 1;
+	sensor->attn_size += reg_desc->reg_size;
+}
+
 static irqreturn_t rmi_f12_attention(int irq, void *ctx)
 {
 	int retval;
@@ -315,6 +350,40 @@ static int rmi_f12_config(struct rmi_function *fn)
 	return 0;
 }
 
+static int rmi_f12_sensor_init(struct rmi_function *fn, struct f12_data *f12)
+{
+	struct rmi_2d_sensor *sensor = &f12->sensor;
+
+	sensor->fn = fn;
+	f12->data_addr = fn->fd.data_base_addr;
+
+	/* On quirky devices that don't have a data_reg_desc we hardcode the packet
+	 * in rmi_f12_set_hardcoded_desc(). Make sure not to set it to 0 here.
+	 */
+	if (!sensor->pkt_size)
+		sensor->pkt_size = rmi_register_desc_calc_size(&f12->data_reg_desc);
+
+	sensor->axis_align =
+		f12->sensor_pdata.axis_align;
+
+	sensor->x_mm = f12->sensor_pdata.x_mm;
+	sensor->y_mm = f12->sensor_pdata.y_mm;
+	sensor->dribble = f12->sensor_pdata.dribble;
+
+	if (sensor->sensor_type == rmi_sensor_default)
+		sensor->sensor_type =
+			f12->sensor_pdata.sensor_type;
+
+	rmi_dbg(RMI_DEBUG_FN, &fn->dev, "%s: data packet size: %d\n", __func__,
+		sensor->pkt_size);
+
+	sensor->data_pkt = devm_kzalloc(&fn->dev, sensor->pkt_size, GFP_KERNEL);
+	if (!sensor->data_pkt)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static int rmi_f12_probe(struct rmi_function *fn)
 {
 	struct f12_data *f12;
@@ -328,6 +397,7 @@ static int rmi_f12_probe(struct rmi_function *fn)
 	struct rmi_driver_data *drvdata = dev_get_drvdata(&rmi_dev->dev);
 	u16 data_offset = 0;
 	int mask_size;
+	bool hardcoded_desc_quirk = false;
 
 	rmi_dbg(RMI_DEBUG_FN, &fn->dev, "%s\n", __func__);
 
@@ -342,9 +412,9 @@ static int rmi_f12_probe(struct rmi_function *fn)
 	++query_addr;
 
 	if (!(buf & BIT(0))) {
-		dev_err(&fn->dev,
-			"Behavior of F12 without register descriptors is undefined.\n");
-		return -ENODEV;
+		rmi_dbg(RMI_DEBUG_FN, &fn->dev,
+			"No register descriptors defined for F12, using fallback\n");
+		hardcoded_desc_quirk = true;
 	}
 
 	f12 = devm_kzalloc(&fn->dev, sizeof(struct f12_data) + mask_size * 2,
@@ -352,6 +422,8 @@ static int rmi_f12_probe(struct rmi_function *fn)
 	if (!f12)
 		return -ENOMEM;
 
+	dev_set_drvdata(&fn->dev, f12);
+
 	f12->abs_mask = (unsigned long *)((char *)f12
 			+ sizeof(struct f12_data));
 	f12->rel_mask = (unsigned long *)((char *)f12
@@ -370,6 +442,18 @@ static int rmi_f12_probe(struct rmi_function *fn)
 		f12->sensor_pdata = pdata->sensor_pdata;
 	}
 
+	sensor = &f12->sensor;
+
+	if (hardcoded_desc_quirk) {
+		rmi_f12_set_hardcoded_desc(fn, f12);
+
+		ret = rmi_f12_sensor_init(fn, f12);
+		if (ret)
+			return ret;
+
+		goto skip_register_desc;
+	}
+
 	ret = rmi_read_register_desc(rmi_dev, query_addr,
 					&f12->query_reg_desc);
 	if (ret) {
@@ -400,29 +484,9 @@ static int rmi_f12_probe(struct rmi_function *fn)
 	}
 	query_addr += 3;
 
-	sensor = &f12->sensor;
-	sensor->fn = fn;
-	f12->data_addr = fn->fd.data_base_addr;
-	sensor->pkt_size = rmi_register_desc_calc_size(&f12->data_reg_desc);
-
-	sensor->axis_align =
-		f12->sensor_pdata.axis_align;
-
-	sensor->x_mm = f12->sensor_pdata.x_mm;
-	sensor->y_mm = f12->sensor_pdata.y_mm;
-	sensor->dribble = f12->sensor_pdata.dribble;
-
-	if (sensor->sensor_type == rmi_sensor_default)
-		sensor->sensor_type =
-			f12->sensor_pdata.sensor_type;
-
-	rmi_dbg(RMI_DEBUG_FN, &fn->dev, "%s: data packet size: %d\n", __func__,
-		sensor->pkt_size);
-	sensor->data_pkt = devm_kzalloc(&fn->dev, sensor->pkt_size, GFP_KERNEL);
-	if (!sensor->data_pkt)
-		return -ENOMEM;
-
-	dev_set_drvdata(&fn->dev, f12);
+	ret = rmi_f12_sensor_init(fn, f12);
+	if (ret)
+		return ret;
 
 	ret = rmi_f12_read_sensor_tuning(f12);
 	if (ret)
@@ -520,6 +584,7 @@ static int rmi_f12_probe(struct rmi_function *fn)
 		data_offset += item->reg_size;
 	}
 
+skip_register_desc:
 	/* allocate the in-kernel tracking buffers */
 	sensor->tracking_pos = devm_kcalloc(&fn->dev,
 			sensor->nbr_fingers, sizeof(struct input_mt_pos),

-- 
2.42.0