Input: synaptics-rmi4 - unmask F03 interrupts when port is opened

Currently we register the pass-through serio port when we probe the F03 RMI
function, and then, in sensor configure phase, we unmask interrupts.
Unfortunately this is too late, as other drivers are free probe devices
attached to the serio port as soon as it is probed. Because interrupts are
masked, the IO times out, which may result in not being able to detect
trackpoints on the pass-through port.

To fix the issue we implement open() and close() methods for the
pass-through serio port and unmask interrupts from there. We also move
creation of the pass-through port form probe to configure stage, as RMI
driver does not enable transport interrupt until all functions are probed
(we should change this, but this is a separate topic).

We also try to clear the pending data before unmasking interrupts, because
some devices like to spam the system with multiple 0xaa 0x00 announcements,
which may interfere with us trying to query ID of the device.

Fixes: c5e8848f ("Input: synaptics-rmi4 - add support for F03")
Cc: stable@vger.kernel.org
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/rmi4/rmi_f03.c

@@ -32,6 +32,7 @@ struct f03_data {
 	struct rmi_function *fn;
 
 	struct serio *serio;
+	bool serio_registered;
 
 	unsigned int overwrite_buttons;
 
@@ -138,6 +139,37 @@ static int rmi_f03_initialize(struct f03_data *f03)
 	return 0;
 }
 
+static int rmi_f03_pt_open(struct serio *serio)
+{
+	struct f03_data *f03 = serio->port_data;
+	struct rmi_function *fn = f03->fn;
+	const u8 ob_len = f03->rx_queue_length * RMI_F03_OB_SIZE;
+	const u16 data_addr = fn->fd.data_base_addr + RMI_F03_OB_OFFSET;
+	u8 obs[RMI_F03_QUEUE_LENGTH * RMI_F03_OB_SIZE];
+	int error;
+
+	/*
+	 * Consume any pending data. Some devices like to spam with
+	 * 0xaa 0x00 announcements which may confuse us as we try to
+	 * probe the device.
+	 */
+	error = rmi_read_block(fn->rmi_dev, data_addr, &obs, ob_len);
+	if (!error)
+		rmi_dbg(RMI_DEBUG_FN, &fn->dev,
+			"%s: Consumed %*ph (%d) from PS2 guest\n",
+			__func__, ob_len, obs, ob_len);
+
+	return fn->rmi_dev->driver->set_irq_bits(fn->rmi_dev, fn->irq_mask);
+}
+
+static void rmi_f03_pt_close(struct serio *serio)
+{
+	struct f03_data *f03 = serio->port_data;
+	struct rmi_function *fn = f03->fn;
+
+	fn->rmi_dev->driver->clear_irq_bits(fn->rmi_dev, fn->irq_mask);
+}
+
 static int rmi_f03_register_pt(struct f03_data *f03)
 {
 	struct serio *serio;
@@ -148,6 +180,8 @@ static int rmi_f03_register_pt(struct f03_data *f03)
 
 	serio->id.type = SERIO_PS_PSTHRU;
 	serio->write = rmi_f03_pt_write;
+	serio->open = rmi_f03_pt_open;
+	serio->close = rmi_f03_pt_close;
 	serio->port_data = f03;
 
 	strlcpy(serio->name, "Synaptics RMI4 PS/2 pass-through",
@@ -184,17 +218,27 @@ static int rmi_f03_probe(struct rmi_function *fn)
 			 f03->device_count);
 
 	dev_set_drvdata(dev, f03);
-
-	error = rmi_f03_register_pt(f03);
-	if (error)
-		return error;
-
 	return 0;
 }
 
 static int rmi_f03_config(struct rmi_function *fn)
 {
+	struct f03_data *f03 = dev_get_drvdata(&fn->dev);
+	int error;
+
+	if (!f03->serio_registered) {
+		error = rmi_f03_register_pt(f03);
+		if (error)
+			return error;
+
+		f03->serio_registered = true;
+	} else {
+		/*
+		 * We must be re-configuring the sensor, just enable
+		 * interrupts for this function.
+		 */
 		fn->rmi_dev->driver->set_irq_bits(fn->rmi_dev, fn->irq_mask);
+	}
 
 	return 0;
 }
@@ -204,7 +248,7 @@ static int rmi_f03_attention(struct rmi_function *fn, unsigned long *irq_bits)
 	struct rmi_device *rmi_dev = fn->rmi_dev;
 	struct rmi_driver_data *drvdata = dev_get_drvdata(&rmi_dev->dev);
 	struct f03_data *f03 = dev_get_drvdata(&fn->dev);
-	u16 data_addr = fn->fd.data_base_addr;
+	const u16 data_addr = fn->fd.data_base_addr + RMI_F03_OB_OFFSET;
 	const u8 ob_len = f03->rx_queue_length * RMI_F03_OB_SIZE;
 	u8 obs[RMI_F03_QUEUE_LENGTH * RMI_F03_OB_SIZE];
 	u8 ob_status;
@@ -226,8 +270,7 @@ static int rmi_f03_attention(struct rmi_function *fn, unsigned long *irq_bits)
 		drvdata->attn_data.size -= ob_len;
 	} else {
 		/* Grab all of the data registers, and check them for data */
-		error = rmi_read_block(fn->rmi_dev, data_addr + RMI_F03_OB_OFFSET,
-				       &obs, ob_len);
+		error = rmi_read_block(fn->rmi_dev, data_addr, &obs, ob_len);
 		if (error) {
 			dev_err(&fn->dev,
 				"%s: Failed to read F03 output buffers: %d\n",
@@ -266,6 +309,7 @@ static void rmi_f03_remove(struct rmi_function *fn)
 {
 	struct f03_data *f03 = dev_get_drvdata(&fn->dev);
 
+	if (f03->serio_registered)
 		serio_unregister_port(f03->serio);
 }