Input: eeti_ts - switch to using threaded interrupt

Instead of having standard interrupt handler and manually firing work item
to perform I2C reads, let's switch to threaded interrupts, which were
designed specifically for this purpose.

Reviewed-by: Daniel Mack <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/touchscreen/eeti_ts.c

···
 struct eeti_ts {
 	struct i2c_client *client;
 	struct input_dev *input;
-	struct work_struct work;
-	struct mutex mutex;
 	int irq_gpio, irq_active_high;
+	bool running;
 };
 
 #define EETI_TS_BITDEPTH	(11)
···
 	return gpio_get_value_cansleep(eeti->irq_gpio) == eeti->irq_active_high;
 }
 
-static void eeti_ts_read(struct work_struct *work)
+static void eeti_ts_report_event(struct eeti_ts *eeti, u8 *buf)
 {
-	char buf[6];
-	unsigned int x, y, res, pressed, to = 100;
-	struct eeti_ts *eeti =
-		container_of(work, struct eeti_ts, work);
+	unsigned int res;
+	u16 x, y;
 
-	mutex_lock(&eeti->mutex);
-
-	while (eeti_ts_irq_active(eeti) && --to)
-		i2c_master_recv(eeti->client, buf, sizeof(buf));
-
-	if (!to) {
-		dev_err(&eeti->client->dev,
-			"unable to clear IRQ - line stuck?\n");
-		goto out;
-	}
-
-	/* drop non-report packets */
-	if (!(buf[0] & 0x80))
-		goto out;
-
-	pressed = buf[0] & REPORT_BIT_PRESSED;
 	res = REPORT_RES_BITS(buf[0] & (REPORT_BIT_AD0 | REPORT_BIT_AD1));
 
 	x = get_unaligned_be16(&buf[1]);
···
 
 	input_report_abs(eeti->input, ABS_X, x);
 	input_report_abs(eeti->input, ABS_Y, y);
-	input_report_key(eeti->input, BTN_TOUCH, !!pressed);
+	input_report_key(eeti->input, BTN_TOUCH, buf[0] & REPORT_BIT_PRESSED);
 	input_sync(eeti->input);
-
-out:
-	mutex_unlock(&eeti->mutex);
 }
 
 static irqreturn_t eeti_ts_isr(int irq, void *dev_id)
 {
 	struct eeti_ts *eeti = dev_id;
+	int len;
+	int error;
+	char buf[6];
 
-	 /* postpone I2C transactions as we are atomic */
-	schedule_work(&eeti->work);
+	do {
+		len = i2c_master_recv(eeti->client, buf, sizeof(buf));
+		if (len != sizeof(buf)) {
+			error = len < 0 ? len : -EIO;
+			dev_err(&eeti->client->dev,
+				"failed to read touchscreen data: %d\n",
+				error);
+			break;
+		}
+
+		if (buf[0] & 0x80) {
+			/* Motion packet */
+			eeti_ts_report_event(eeti, buf);
+		}
+	} while (eeti->running && eeti_ts_irq_active(eeti));
 
 	return IRQ_HANDLED;
 }
 
 static void eeti_ts_start(struct eeti_ts *eeti)
 {
+	eeti->running = true;
+	wmb();
 	enable_irq(eeti->client->irq);
-
-	/* Read the events once to arm the IRQ */
-	eeti_ts_read(&eeti->work);
 }
 
 static void eeti_ts_stop(struct eeti_ts *eeti)
 {
+	eeti->running = false;
+	wmb();
 	disable_irq(eeti->client->irq);
-	cancel_work_sync(&eeti->work);
 }
 
 static int eeti_ts_open(struct input_dev *dev)
···
 		return -ENOMEM;
 	}
 
-	mutex_init(&eeti->mutex);
-
 	input = devm_input_allocate_device(dev);
 	if (!input) {
 		dev_err(dev, "Failed to allocate input device.\n");
···
 	eeti->irq_active_high = pdata->irq_active_high;
 
 	irq_flags = eeti->irq_active_high ?
-		IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
+		IRQF_TRIGGER_HIGH : IRQF_TRIGGER_LOW;
 
-	INIT_WORK(&eeti->work, eeti_ts_read);
 	i2c_set_clientdata(client, eeti);
 	input_set_drvdata(input, eeti);
 
-	error = input_register_device(input);
-	if (error)
-		return error;
-
-	error = devm_request_irq(dev, client->irq, eeti_ts_isr, irq_flags,
-				 client->name, eeti);
+	error = devm_request_threaded_irq(dev, client->irq,
+					  NULL, eeti_ts_isr,
+					  irq_flags | IRQF_ONESHOT,
+					  client->name, eeti);
 	if (error) {
 		dev_err(dev, "Unable to request touchscreen IRQ: %d\n",
 			error);
···
 	 * input device is opened.
 	 */
 	eeti_ts_stop(eeti);
+
+	error = input_register_device(input);
+	if (error)
+		return error;
 
 	return 0;
 }