iio: adis16400: Fix burst transfer for adis16448

The adis16448, unlike the other chips in this family, in addition to the
hardware channels also sends out the DIAG_STAT register in burst mode
before them. Handle that case by skipping over the first 2 bytes before we
pass the received data to the buffer.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Fixes: 76ada52f ("iio:adis16400: Add support for the adis16448")
Cc: <stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/imu/adis16400.h

@@ -139,6 +139,7 @@
 #define ADIS16400_NO_BURST		BIT(1)
 #define ADIS16400_HAS_SLOW_MODE		BIT(2)
 #define ADIS16400_HAS_SERIAL_NUMBER	BIT(3)
+#define ADIS16400_BURST_DIAG_STAT	BIT(4)
 
 struct adis16400_state;
 

drivers/iio/imu/adis16400_buffer.c

@@ -29,6 +29,8 @@ int adis16400_update_scan_mode(struct iio_dev *indio_dev,
 
 	/* All but the timestamp channel */
 	burst_length = (indio_dev->num_channels - 1) * sizeof(u16);
+	if (st->variant->flags & ADIS16400_BURST_DIAG_STAT)
+		burst_length += sizeof(u16);
 
 	adis->xfer = kcalloc(2, sizeof(*adis->xfer), GFP_KERNEL);
 	if (!adis->xfer)
@@ -63,6 +65,7 @@ irqreturn_t adis16400_trigger_handler(int irq, void *p)
 	struct adis16400_state *st = iio_priv(indio_dev);
 	struct adis *adis = &st->adis;
 	u32 old_speed_hz = st->adis.spi->max_speed_hz;
+	void *buffer;
 	int ret;
 
 	if (!adis->buffer)
@@ -83,7 +86,12 @@ irqreturn_t adis16400_trigger_handler(int irq, void *p)
 		spi_setup(st->adis.spi);
 	}
 
-	iio_push_to_buffers_with_timestamp(indio_dev, adis->buffer,
+	if (st->variant->flags & ADIS16400_BURST_DIAG_STAT)
+		buffer = adis->buffer + sizeof(u16);
+	else
+		buffer = adis->buffer;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, buffer,
 		pf->timestamp);
 
 	iio_trigger_notify_done(indio_dev->trig);

drivers/iio/imu/adis16400_core.c

@@ -778,7 +778,8 @@ static struct adis16400_chip_info adis16400_chips[] = {
 		.channels = adis16448_channels,
 		.num_channels = ARRAY_SIZE(adis16448_channels),
 		.flags = ADIS16400_HAS_PROD_ID |
-				ADIS16400_HAS_SERIAL_NUMBER,
+				ADIS16400_HAS_SERIAL_NUMBER |
+				ADIS16400_BURST_DIAG_STAT,
 		.gyro_scale_micro = IIO_DEGREE_TO_RAD(10000), /* 0.01 deg/s */
 		.accel_scale_micro = IIO_G_TO_M_S_2(833), /* 1/1200 g */
 		.temp_scale_nano = 73860000, /* 0.07386 C */