iio: proximity: vl53l0x: Add IRQ support

VL53L0X can be configured to use interrupt pin (GPIO1)
to notify host about readiness of new measurement.

If interrupt pin is not specified, driver still uses polling.
Signed-off-by: Ivan Drobyshevskyi <drobyshevskyi@gmail.com>
Link: https://lore.kernel.org/r/20200916074458.873359-2-drobyshevskyi@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/proximity/vl53l0x-i2c.c

@@ -4,18 +4,19 @@
  *
  * Copyright (C) 2016 STMicroelectronics Imaging Division.
  * Copyright (C) 2018 Song Qiang <songqiang1304521@gmail.com>
+ * Copyright (C) 2020 Ivan Drobyshevskyi <drobyshevskyi@gmail.com>
  *
  * Datasheet available at
  * <https://www.st.com/resource/en/datasheet/vl53l0x.pdf>
  *
  * Default 7-bit i2c slave address 0x29.
  *
- * TODO: FIFO buffer, continuous mode, interrupts, range selection,
- * sensor ID check.
+ * TODO: FIFO buffer, continuous mode, range selection, sensor ID check.
  */
 
 #include <linux/delay.h>
 #include <linux/i2c.h>
+#include <linux/interrupt.h>
 #include <linux/module.h>
 
 #include <linux/iio/iio.h>
@@ -29,14 +30,72 @@
 #define VL_REG_SYSRANGE_MODE_TIMED			BIT(2)
 #define VL_REG_SYSRANGE_MODE_HISTOGRAM			BIT(3)
 
+#define VL_REG_SYSTEM_INTERRUPT_CONFIG_GPIO		0x0A
+#define VL_REG_SYSTEM_INTERRUPT_GPIO_NEW_SAMPLE_READY	BIT(2)
+
+#define VL_REG_SYSTEM_INTERRUPT_CLEAR			0x0B
+
 #define VL_REG_RESULT_INT_STATUS			0x13
 #define VL_REG_RESULT_RANGE_STATUS			0x14
 #define VL_REG_RESULT_RANGE_STATUS_COMPLETE		BIT(0)
 
 struct vl53l0x_data {
 	struct i2c_client *client;
+	struct completion completion;
 };
 
+static irqreturn_t vl53l0x_handle_irq(int irq, void *priv)
+{
+	struct iio_dev *indio_dev = priv;
+	struct vl53l0x_data *data = iio_priv(indio_dev);
+
+	complete(&data->completion);
+
+	return IRQ_HANDLED;
+}
+
+static int vl53l0x_configure_irq(struct i2c_client *client,
+				 struct iio_dev *indio_dev)
+{
+	struct vl53l0x_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = devm_request_irq(&client->dev, client->irq, vl53l0x_handle_irq,
+			IRQF_TRIGGER_FALLING, indio_dev->name, indio_dev);
+	if (ret) {
+		dev_err(&client->dev, "devm_request_irq error: %d\n", ret);
+		return ret;
+	}
+
+	ret = i2c_smbus_write_byte_data(data->client,
+			VL_REG_SYSTEM_INTERRUPT_CONFIG_GPIO,
+			VL_REG_SYSTEM_INTERRUPT_GPIO_NEW_SAMPLE_READY);
+	if (ret < 0)
+		dev_err(&client->dev, "failed to configure IRQ: %d\n", ret);
+
+	return ret;
+}
+
+static void vl53l0x_clear_irq(struct vl53l0x_data *data)
+{
+	struct device *dev = &data->client->dev;
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(data->client,
+					VL_REG_SYSTEM_INTERRUPT_CLEAR, 1);
+	if (ret < 0)
+		dev_err(dev, "failed to clear error irq: %d\n", ret);
+
+	ret = i2c_smbus_write_byte_data(data->client,
+					VL_REG_SYSTEM_INTERRUPT_CLEAR, 0);
+	if (ret < 0)
+		dev_err(dev, "failed to clear range irq: %d\n", ret);
+
+	ret = i2c_smbus_read_byte_data(data->client, VL_REG_RESULT_INT_STATUS);
+	if (ret < 0 || ret & 0x07)
+		dev_err(dev, "failed to clear irq: %d\n", ret);
+}
+
 static int vl53l0x_read_proximity(struct vl53l0x_data *data,
 				  const struct iio_chan_spec *chan,
 				  int *val)
@@ -50,19 +109,31 @@ static int vl53l0x_read_proximity(struct vl53l0x_data *data,
 	if (ret < 0)
 		return ret;
 
-	do {
-		ret = i2c_smbus_read_byte_data(client,
-					       VL_REG_RESULT_RANGE_STATUS);
+	if (data->client->irq) {
+		reinit_completion(&data->completion);
+
+		ret = wait_for_completion_timeout(&data->completion, HZ/10);
 		if (ret < 0)
 			return ret;
+		else if (ret == 0)
+			return -ETIMEDOUT;
 
-		if (ret & VL_REG_RESULT_RANGE_STATUS_COMPLETE)
-			break;
+		vl53l0x_clear_irq(data);
+	} else {
+		do {
+			ret = i2c_smbus_read_byte_data(client,
+					       VL_REG_RESULT_RANGE_STATUS);
+			if (ret < 0)
+				return ret;
 
-		usleep_range(1000, 5000);
-	} while (--tries);
-	if (!tries)
-		return -ETIMEDOUT;
+			if (ret & VL_REG_RESULT_RANGE_STATUS_COMPLETE)
+				break;
+
+			usleep_range(1000, 5000);
+		} while (--tries);
+		if (!tries)
+			return -ETIMEDOUT;
+	}
 
 	ret = i2c_smbus_read_i2c_block_data(client, VL_REG_RESULT_RANGE_STATUS,
 					    12, buffer);
@@ -140,6 +211,17 @@ static int vl53l0x_probe(struct i2c_client *client)
 	indio_dev->num_channels = ARRAY_SIZE(vl53l0x_channels);
 	indio_dev->modes = INDIO_DIRECT_MODE;
 
+	/* usage of interrupt is optional */
+	if (client->irq) {
+		int ret;
+
+		init_completion(&data->completion);
+
+		ret = vl53l0x_configure_irq(client, indio_dev);
+		if (ret)
+			return ret;
+	}
+
 	return devm_iio_device_register(&client->dev, indio_dev);
 }