Input: ili210x - switch to using threaded IRQ

Let's switch the driver to using threaded IRQ so that we do not need to
manage the interrupt and work separately, and we do not acknowledge
interrupt until we finished handling it completely.

Tested-by: Adam Ford <aford173@gmail.com> #imx6q-logicpd
Tested-by: Sven Van Asbroeck <TheSven73@gmail.com> # ILI2118A variant
Tested-by: Marek Vasut <marex@denx.de> #  ILI2117
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/ili210x.c

 // SPDX-License-Identifier: GPL-2.0-only
-#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
-#include <linux/interrupt.h>
-#include <linux/slab.h>
 #include <linux/input.h>
 #include <linux/input/mt.h>
 #include <linux/input/touchscreen.h>
-#include <linux/delay.h>
-#include <linux/workqueue.h>
-#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/slab.h>
 #include <asm/unaligned.h>
 
 #define ILI210X_TOUCHES		2
 #define ILI211X_TOUCHES		10
 #define ILI251X_TOUCHES		10
-#define DEFAULT_POLL_PERIOD	20
+
+#define ILI2XXX_POLL_PERIOD	20
 
 /* Touchscreen commands */
 #define REG_TOUCHDATA		0x10
@@ -38,12 +38,11 @@ enum ili2xxx_model {
 struct ili210x {
 	struct i2c_client *client;
 	struct input_dev *input;
-	unsigned int poll_period;
-	struct delayed_work dwork;
 	struct gpio_desc *reset_gpio;
 	struct touchscreen_properties prop;
 	enum ili2xxx_model model;
 	unsigned int max_touches;
+	bool stop;
 };
 
 static int ili210x_read_reg(struct i2c_client *client, u8 reg, void *buf,
@@ -196,57 +195,54 @@ static bool ili210x_report_events(struct ili210x *priv, u8 *touchdata)
 	return contact;
 }
 
-static void ili210x_work(struct work_struct *work)
+static irqreturn_t ili210x_irq(int irq, void *irq_data)
 {
-	struct ili210x *priv = container_of(work, struct ili210x,
-					    dwork.work);
+	struct ili210x *priv = irq_data;
 	struct i2c_client *client = priv->client;
 	u8 touchdata[64] = { 0 };
 	s16 sum = 0;
 	bool touch;
-	int i, error = -EINVAL;
-
-	if (priv->model == MODEL_ILI210X) {
-		error = ili210x_read_reg(client, REG_TOUCHDATA,
-					 touchdata, sizeof(touchdata));
-	} else if (priv->model == MODEL_ILI211X) {
-		error = ili210x_read(client, touchdata, 43);
-		if (!error) {
-			/* This chip uses custom checksum at the end of data */
-			for (i = 0; i <= 41; i++)
-				sum = (sum + touchdata[i]) & 0xff;
-			if ((-sum & 0xff) != touchdata[42]) {
-				dev_err(&client->dev,
-					"CRC error (crc=0x%02x expected=0x%02x)\n",
-					sum, touchdata[42]);
-				return;
+	int i;
+	int error;
+
+	do {
+		if (priv->model == MODEL_ILI210X) {
+			error = ili210x_read_reg(client, REG_TOUCHDATA,
+						 touchdata, sizeof(touchdata));
+		} else if (priv->model == MODEL_ILI211X) {
+			error = ili210x_read(client, touchdata, 43);
+			if (!error) {
+				/*
+				 * This chip uses custom checksum at the end
+				 * of data.
+				 */
+				for (i = 0; i <= 41; i++)
+					sum = (sum + touchdata[i]) & 0xff;
+				if ((-sum & 0xff) != touchdata[42]) {
+					dev_err(&client->dev,
+						"CRC error (crc=0x%02x expected=0x%02x)\n",
+						sum, touchdata[42]);
+					break;
+				}
 			}
+		} else if (priv->model == MODEL_ILI251X) {
+			error = ili210x_read_reg(client, REG_TOUCHDATA,
+						 touchdata, 31);
+			if (!error && touchdata[0] == 2)
+				error = ili210x_read(client,
+						     &touchdata[31], 20);
 		}
-	} else if (priv->model == MODEL_ILI251X) {
-		error = ili210x_read_reg(client, REG_TOUCHDATA,
-					 touchdata, 31);
-		if (!error && touchdata[0] == 2)
-			error = ili210x_read(client, &touchdata[31], 20);
-	}
-
-	if (error) {
-		dev_err(&client->dev,
-			"Unable to get touchdata, err = %d\n", error);
-		return;
-	}
 
-	touch = ili210x_report_events(priv, touchdata);
-
-	if (touch)
-		schedule_delayed_work(&priv->dwork,
-				      msecs_to_jiffies(priv->poll_period));
-}
-
-static irqreturn_t ili210x_irq(int irq, void *irq_data)
-{
-	struct ili210x *priv = irq_data;
+		if (error) {
+			dev_err(&client->dev,
+				"Unable to get touchdata, err = %d\n", error);
+			break;
+		}
 
-	schedule_delayed_work(&priv->dwork, 0);
+		touch = ili210x_report_events(priv, touchdata);
+		if (touch)
+			msleep(ILI2XXX_POLL_PERIOD);
+	} while (!priv->stop && touch);
 
 	return IRQ_HANDLED;
 }
@@ -293,11 +289,12 @@ static void ili210x_power_down(void *data)
 	gpiod_set_value_cansleep(reset_gpio, 1);
 }
 
-static void ili210x_cancel_work(void *data)
+static void ili210x_stop(void *data)
 {
 	struct ili210x *priv = data;
 
-	cancel_delayed_work_sync(&priv->dwork);
+	/* Tell ISR to quit even if there is a contact. */
+	priv->stop = true;
 }
 
 static int ili210x_i2c_probe(struct i2c_client *client,
@@ -345,8 +342,6 @@ static int ili210x_i2c_probe(struct i2c_client *client,
 
 	priv->client = client;
 	priv->input = input;
-	priv->poll_period = DEFAULT_POLL_PERIOD;
-	INIT_DELAYED_WORK(&priv->dwork, ili210x_work);
 	priv->reset_gpio = reset_gpio;
 	priv->model = model;
 	if (model == MODEL_ILI210X)
@@ -378,18 +373,18 @@ static int ili210x_i2c_probe(struct i2c_client *client,
 	touchscreen_parse_properties(input, true, &priv->prop);
 	input_mt_init_slots(input, priv->max_touches, INPUT_MT_DIRECT);
 
-	error = devm_add_action(dev, ili210x_cancel_work, priv);
-	if (error)
-		return error;
-
-	error = devm_request_irq(dev, client->irq, ili210x_irq, 0,
-				 client->name, priv);
+	error = devm_request_threaded_irq(dev, client->irq, NULL, ili210x_irq,
+					  IRQF_ONESHOT, client->name, priv);
 	if (error) {
 		dev_err(dev, "Unable to request touchscreen IRQ, err: %d\n",
 			error);
 		return error;
 	}
 
+	error = devm_add_action_or_reset(dev, ili210x_stop, priv);
+	if (error)
+		return error;
+
 	error = devm_device_add_group(dev, &ili210x_attr_group);
 	if (error) {
 		dev_err(dev, "Unable to create sysfs attributes, err: %d\n",