IIO: ADC: AD799x: Update timestamp handling

Add timestamp attributes.
Revise timestamp handling accordingly.
Preset timestamp generation.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/adc/ad799x.h

@@ -116,6 +116,7 @@ struct ad799x_state {
 	struct work_struct		poll_work;
 	struct work_struct		work_thresh;
 	atomic_t			protect_ring;
+	size_t				d_size;
 	struct iio_trigger		*trig;
 	struct regulator		*reg;
 	s64				last_timestamp;

drivers/staging/iio/adc/ad799x_core.c

@@ -123,6 +123,9 @@ static AD799X_SCAN_EL(5);
 static AD799X_SCAN_EL(6);
 static AD799X_SCAN_EL(7);
 
+static IIO_SCAN_EL_TIMESTAMP(8);
+static IIO_CONST_ATTR_SCAN_EL_TYPE(timestamp, s, 64, 64)
+
 static ssize_t ad799x_show_type(struct device *dev,
 				struct device_attribute *attr,
 				char *buf)
@@ -471,6 +474,9 @@ static struct attribute *ad7991_5_9_3_4_scan_el_attrs[] = {
 	&iio_const_attr_in2_index.dev_attr.attr,
 	&iio_scan_el_in3.dev_attr.attr,
 	&iio_const_attr_in3_index.dev_attr.attr,
+	&iio_const_attr_timestamp_index.dev_attr.attr,
+	&iio_scan_el_timestamp.dev_attr.attr,
+	&iio_const_attr_timestamp_type.dev_attr.attr,
 	&iio_dev_attr_in_type.dev_attr.attr,
 	NULL,
 };
@@ -497,6 +503,9 @@ static struct attribute *ad7992_scan_el_attrs[] = {
 	&iio_const_attr_in0_index.dev_attr.attr,
 	&iio_scan_el_in1.dev_attr.attr,
 	&iio_const_attr_in1_index.dev_attr.attr,
+	&iio_const_attr_timestamp_index.dev_attr.attr,
+	&iio_scan_el_timestamp.dev_attr.attr,
+	&iio_const_attr_timestamp_type.dev_attr.attr,
 	&iio_dev_attr_in_type.dev_attr.attr,
 	NULL,
 };
@@ -541,6 +550,9 @@ static struct attribute *ad7997_8_scan_el_attrs[] = {
 	&iio_const_attr_in6_index.dev_attr.attr,
 	&iio_scan_el_in7.dev_attr.attr,
 	&iio_const_attr_in7_index.dev_attr.attr,
+	&iio_const_attr_timestamp_index.dev_attr.attr,
+	&iio_scan_el_timestamp.dev_attr.attr,
+	&iio_const_attr_timestamp_type.dev_attr.attr,
 	&iio_dev_attr_in_type.dev_attr.attr,
 	NULL,
 };

drivers/staging/iio/adc/ad799x_ring.c

@@ -73,8 +73,6 @@ static int ad799x_ring_preenable(struct iio_dev *indio_dev)
 {
 	struct iio_ring_buffer *ring = indio_dev->ring;
 	struct ad799x_state *st = indio_dev->dev_data;
-	size_t d_size;
-	unsigned long numvals;
 
 	/*
 	 * Need to figure out the current mode based upon the requested
@@ -84,15 +82,19 @@ static int ad799x_ring_preenable(struct iio_dev *indio_dev)
 	if (st->id == ad7997 || st->id == ad7998)
 		ad799x_set_scan_mode(st, ring->scan_mask);
 
-	numvals = ring->scan_count;
+	st->d_size = ring->scan_count * 2;
 
-	if (ring->access.set_bytes_per_datum) {
-		d_size = numvals*2 + sizeof(s64);
-		if (d_size % 8)
-			d_size += 8 - (d_size % 8);
-		ring->access.set_bytes_per_datum(ring, d_size);
+	if (ring->scan_timestamp) {
+		st->d_size += sizeof(s64);
+
+		if (st->d_size % sizeof(s64))
+			st->d_size += sizeof(s64) - (st->d_size % sizeof(s64));
 	}
 
+	if (indio_dev->ring->access.set_bytes_per_datum)
+		indio_dev->ring->access.set_bytes_per_datum(indio_dev->ring,
+							    st->d_size);
+
 	return 0;
 }
 
@@ -130,29 +132,13 @@ static void ad799x_poll_bh_to_ring(struct work_struct *work_s)
 	s64 time_ns;
 	__u8 *rxbuf;
 	int b_sent;
-	size_t d_size;
 	u8 cmd;
 
-	unsigned long numvals = ring->scan_count;
-
-	/* Ensure the timestamp is 8 byte aligned */
-	d_size = numvals*2 + sizeof(s64);
-
-	if (d_size % sizeof(s64))
-		d_size += sizeof(s64) - (d_size % sizeof(s64));
-
 	/* Ensure only one copy of this function running at a time */
 	if (atomic_inc_return(&st->protect_ring) > 1)
 		return;
 
-	/* Monitor mode prevents reading. Whilst not currently implemented
-	 * might as well have this test in here in the meantime as it does
-	 * no harm.
-	 */
-	if (numvals == 0)
-		return;
-
-	rxbuf = kmalloc(d_size,	GFP_KERNEL);
+	rxbuf = kmalloc(st->d_size, GFP_KERNEL);
 	if (rxbuf == NULL)
 		return;
 
@@ -177,13 +163,15 @@ static void ad799x_poll_bh_to_ring(struct work_struct *work_s)
 	}
 
 	b_sent = i2c_smbus_read_i2c_block_data(st->client,
-			cmd, numvals*2, rxbuf);
+			cmd, ring->scan_count * 2, rxbuf);
 	if (b_sent < 0)
 		goto done;
 
 	time_ns = iio_get_time_ns();
 
-	memcpy(rxbuf + d_size - sizeof(s64), &time_ns, sizeof(time_ns));
+	if (ring->scan_timestamp)
+		memcpy(rxbuf + st->d_size - sizeof(s64),
+			&time_ns, sizeof(time_ns));
 
 	ring->access.store_to(&ring_sw->buf, rxbuf, time_ns);
 done:
@@ -213,6 +201,7 @@ int ad799x_register_ring_funcs_and_init(struct iio_dev *indio_dev)
 	indio_dev->ring->preenable = &ad799x_ring_preenable;
 	indio_dev->ring->postenable = &iio_triggered_ring_postenable;
 	indio_dev->ring->predisable = &iio_triggered_ring_predisable;
+	indio_dev->ring->scan_timestamp = true;
 
 	INIT_WORK(&st->poll_work, &ad799x_poll_bh_to_ring);