staging: iio: adc: ad7606: Use wait-for-completion handler

This patch replaces the use of wait_event_interruptible() with
wait_for_completion_timeout() when reading the result of a single
conversion. In this way, if the interrupt never occurs, the program will
not remain blocked.
Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/adc/ad7606.c

@@ -119,12 +119,13 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
 	struct ad7606_state *st = iio_priv(indio_dev);
 	int ret;
 
-	st->done = false;
 	gpiod_set_value(st->gpio_convst, 1);
-
-	ret = wait_event_interruptible(st->wq_data_avail, st->done);
-	if (ret)
+	ret = wait_for_completion_timeout(&st->completion,
+					  msecs_to_jiffies(1000));
+	if (!ret) {
+		ret = -ETIMEDOUT;
 		goto error_ret;
+	}
 
 	ret = ad7606_read_samples(st);
 	if (ret == 0)
@@ -389,8 +390,7 @@ static irqreturn_t ad7606_interrupt(int irq, void *dev_id)
 	if (iio_buffer_enabled(indio_dev)) {
 		schedule_work(&st->poll_work);
 	} else {
-		st->done = true;
-		wake_up_interruptible(&st->wq_data_avail);
+		complete(&st->completion);
 	}
 
 	return IRQ_HANDLED;
@@ -474,7 +474,7 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
 	indio_dev->channels = st->chip_info->channels;
 	indio_dev->num_channels = st->chip_info->num_channels;
 
-	init_waitqueue_head(&st->wq_data_avail);
+	init_completion(&st->completion);
 
 	ret = ad7606_reset(st);
 	if (ret)

drivers/staging/iio/adc/ad7606.h

@@ -29,11 +29,9 @@ struct ad7606_chip_info {
  * @reg		regulator info for the the power supply of the device
  * @poll_work		work struct for continuously reading data from the device
  *			into an IIO triggered buffer
- * @wq_data_avail	wait queue struct for buffer mode
  * @bops		bus operations (SPI or parallel)
  * @range		voltage range selection, selects which scale to apply
  * @oversampling	oversampling selection
- * @done		marks whether reading data is done
  * @base_address	address from where to read data in parallel operation
  * @lock		protect sensor state from concurrent accesses to GPIOs
  * @gpio_convst	GPIO descriptor for conversion start signal (CONVST)
@@ -44,6 +42,7 @@ struct ad7606_chip_info {
  * @gpio_frstdata	GPIO descriptor for reading from device when data
  *			is being read on the first channel
  * @gpio_os		GPIO descriptors to control oversampling on the device
+ * @complete		completion to indicate end of conversion
  * @data		buffer for reading data from the device
  */
 
@@ -52,11 +51,9 @@ struct ad7606_state {
 	const struct ad7606_chip_info	*chip_info;
 	struct regulator		*reg;
 	struct work_struct		poll_work;
-	wait_queue_head_t		wq_data_avail;
 	const struct ad7606_bus_ops	*bops;
 	unsigned int			range;
 	unsigned int			oversampling;
-	bool				done;
 	void __iomem			*base_address;
 
 	struct mutex			lock; /* protect sensor state */
@@ -66,6 +63,7 @@ struct ad7606_state {
 	struct gpio_desc		*gpio_standby;
 	struct gpio_desc		*gpio_frstdata;
 	struct gpio_descs		*gpio_os;
+	struct completion		completion;
 
 	/*
 	 * DMA (thus cache coherency maintenance) requires the