On Sun, 17 Nov 2024 18:26:46 +0000
Lothar Rubusch <l.rubusch@xxxxxxxxx> wrote:
> Add FIFO and hwfifo handling. Add some functions to deal with FIFO
> entries and configuration. This feature will be needed for e.g.
> watermark setting.
>
> Signed-off-by: Lothar Rubusch <l.rubusch@xxxxxxxxx>
> ---
> drivers/iio/accel/adxl345_core.c | 38 ++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
> index d58e1994ff..a653774db8 100644
> --- a/drivers/iio/accel/adxl345_core.c
> +++ b/drivers/iio/accel/adxl345_core.c
> @@ -437,6 +437,41 @@ static int adxl345_get_status(struct adxl34x_state *st, u8 *int_stat)
> return 0;
> }
>
> +static int adxl345_push_fifo_data(struct iio_dev *indio_dev,
> + u8 status,
> + int fifo_entries)
> +{
> + struct adxl34x_state *st = iio_priv(indio_dev);
> + int ndirs = 3; /* 3 directions */
It's const. Maybe a define is appropriate instead?
> + int i, ret;
> +
> + if (fifo_entries <= 0)
> + return true;
It returns an int. Also how did you get in here with negative fifo
entries? That rather suggests something went wrong at the caller.
> +
> + ret = adxl345_read_fifo_elements(st, fifo_entries);
> + if (ret)
> + return false;
> +
> + for (i = 0; i < ndirs * fifo_entries; i += ndirs) {
> + /* To ensure that the FIFO has completely popped, there must be at least 5
Comment format.
> + * us between the end of reading the data registers, signified by the
> + * transition to register 0x38 from 0x37 or the CS pin going high, and the
> + * start of new reads of the FIFO or reading the FIFO_STATUS register. For
> + * SPI operation at 1.5 MHz or lower, the register addressing portion of the
> + * transmission is sufficient delay to ensure the FIFO has completely
> + * popped. It is necessary for SPI operation greater than 1.5 MHz to
> + * de-assert the CS pin to ensure a total of 5 us, which is at most 3.4 us
> + * at 5 MHz operation.
> + */
> + if (st->fifo_delay && (fifo_entries > 1))
> + udelay(3);
> +
> + iio_push_to_buffers(indio_dev, &st->fifo_buf[i]);
> + }
> +
> + return true;
> +}
> +
