iio: adis: Support different burst sizes

Add burst_max_len to `adis_burst`. This is useful for devices which
support different burst modes with different sizes. The buffer to be
used in the spi transfer is allocated with this variable making sure
that has space for all burst modes. The spi transfer length should hold
the "real" burst length depending on the current burst mode configured
in the device.

Moreover, `extra_len` in `adis_burst` is made const and it should
contain the smallest extra length necessary for a burst transfer. In
`struct adis` was added a new `burst_extra_len` that should hold the
extra bytes needed depending on the device instance being used.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/imu/adis16400.c b/drivers/iio/imu/adis16400.c
index 4445c24..439feb7 100644 (file)
--- a/drivers/iio/imu/adis16400.c
+++ b/drivers/iio/imu/adis16400.c
@@ -1195,7 +1195,7 @@ static int adis16400_probe(struct spi_device *spi)
                indio_dev->available_scan_masks = st->avail_scan_mask;
                st->adis.burst = &adis16400_burst;
                if (st->variant->flags & ADIS16400_BURST_DIAG_STAT)
-                       st->adis.burst->extra_len = sizeof(u16);
+                       st->adis.burst_extra_len = sizeof(u16);
        }
 
        adis16400_data = &st->variant->adis_data;

diff --git a/drivers/iio/imu/adis_buffer.c b/drivers/iio/imu/adis_buffer.c
index 8fdc4dc..5b4225e 100644 (file)
--- a/drivers/iio/imu/adis_buffer.c
+++ b/drivers/iio/imu/adis_buffer.c
@@ -23,25 +23,30 @@ static int adis_update_scan_mode_burst(struct iio_dev *indio_dev,
        const unsigned long *scan_mask)
 {
        struct adis *adis = iio_device_get_drvdata(indio_dev);
-       unsigned int burst_length;
+       unsigned int burst_length, burst_max_length;
        u8 *tx;
 
        /* All but the timestamp channel */
        burst_length = (indio_dev->num_channels - 1) * sizeof(u16);
-       burst_length += adis->burst->extra_len;
+       burst_length += adis->burst->extra_len + adis->burst_extra_len;
+
+       if (adis->burst->burst_max_len)
+               burst_max_length = adis->burst->burst_max_len;
+       else
+               burst_max_length = burst_length;
 
        adis->xfer = kcalloc(2, sizeof(*adis->xfer), GFP_KERNEL);
        if (!adis->xfer)
                return -ENOMEM;
 
-       adis->buffer = kzalloc(burst_length + sizeof(u16), GFP_KERNEL);
+       adis->buffer = kzalloc(burst_max_length + sizeof(u16), GFP_KERNEL);
        if (!adis->buffer) {
                kfree(adis->xfer);
                adis->xfer = NULL;
                return -ENOMEM;
        }
 
-       tx = adis->buffer + burst_length;
+       tx = adis->buffer + burst_max_length;
        tx[0] = ADIS_READ_REG(adis->burst->reg_cmd);
        tx[1] = 0;
 

diff --git a/include/linux/iio/imu/adis.h b/include/linux/iio/imu/adis.h
index 247fc4c..2df6744 100644 (file)
--- a/include/linux/iio/imu/adis.h
+++ b/include/linux/iio/imu/adis.h
@@ -83,6 +83,8 @@ struct adis_data {
  * @trig: IIO trigger object data
  * @data: ADIS chip variant specific data
  * @burst: ADIS burst transfer information
+ * @burst_extra_len: Burst extra length. Should only be used by devices that can
+ *                  dynamically change their burst mode length.
  * @state_lock: Lock used by the device to protect state
  * @msg: SPI message object
  * @xfer: SPI transfer objects to be used for a @msg
@@ -98,7 +100,7 @@ struct adis {
 
        const struct adis_data  *data;
        struct adis_burst       *burst;
-
+       unsigned int            burst_extra_len;
        /**
         * The state_lock is meant to be used during operations that require
         * a sequence of SPI R/W in order to protect the SPI transfer
@@ -502,11 +504,14 @@ int adis_single_conversion(struct iio_dev *indio_dev,
  * @en                 burst mode enabled
  * @reg_cmd            register command that triggers burst
  * @extra_len          extra length to account in the SPI RX buffer
+ * @burst_max_len      holds the maximum burst size when the device supports
+ *                     more than one burst mode with different sizes
  */
 struct adis_burst {
        bool            en;
        unsigned int    reg_cmd;
-       unsigned int    extra_len;
+       const u32       extra_len;
+       const u32       burst_max_len;
 };
 
 int