On Thu, 29 Aug 2024 14:32:00 +0200
Angelo Dureghello <adureghello@xxxxxxxxxxxx> wrote:
> From: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
>
> Extend backend features with new calls needed later on this
> patchset from axi version of ad3552r.
>
> A bus type property has been added to the devicetree to
> inform the backend about the type of bus (interface) in use
> bu the IP.
>
> The follwoing calls are added:
>
> iio_backend_ext_sync_enable
> enable synchronize channels on external trigger
> iio_backend_ext_sync_disable
> disable synchronize channels on external trigger
> iio_backend_ddr_enable
> enable ddr bus transfer
> iio_backend_ddr_disable
> disable ddr bus transfer
> iio_backend_set_bus_mode
> select the type of bus, so that specific read / write
> operations are performed accordingly
> iio_backend_buffer_enable
> enable buffer
> iio_backend_buffer_disable
> disable buffer
> iio_backend_data_transfer_addr
> define the target register address where the DAC sample
> will be written.
> iio_backend_bus_reg_read
> generic bus read, bus-type dependent
> iio_backend_bus_read_write
> generic bus write, bus-type dependent
>
> Signed-off-by: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
> ---
> drivers/iio/industrialio-backend.c | 151 +++++++++++++++++++++++++++++++++++++
> include/linux/iio/backend.h | 24 ++++++
> 2 files changed, 175 insertions(+)
>
> diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
> index a52a6b61c8b5..1f60c8626be7 100644
> --- a/drivers/iio/industrialio-backend.c
> +++ b/drivers/iio/industrialio-backend.c
> @@ -718,6 +718,157 @@ static int __devm_iio_backend_get(struct device *dev, struct iio_backend *back)
> return 0;
> }
> +
> +/**
> + * iio_backend_buffer_enable - Enable data buffering
Data buffering is a very vague term. Perhaps some more detail on what
this means?
> + * @back: Backend device
> + *
> + * RETURNS:
> + * 0 on success, negative error number on failure.
> + */
> +int iio_backend_buffer_enable(struct iio_backend *back)
> +{
> + return iio_backend_op_call(back, buffer_enable);
> +}
> +EXPORT_SYMBOL_NS_GPL(iio_backend_buffer_enable, IIO_BACKEND);
> +
> +/**
> + * iio_backend_set_buffer_disable - Disable data buffering
> + * @back: Backend device
> + *
> + * RETURNS:
> + * 0 on success, negative error number on failure.
> + */
> +int iio_backend_buffer_disable(struct iio_backend *back)
> +{
> + return iio_backend_op_call(back, buffer_disable);
> +}
> +EXPORT_SYMBOL_NS_GPL(iio_backend_buffer_disable, IIO_BACKEND);
> +
> +/**
> + * iio_backend_buffer_transfer_addr - Set data address.
> + * @back: Backend device
> + * @chan_address: Channel register address
Run scripts/kernel-doc on this and fix the errors (parameter name is
wrong). W=1 builds might also point the simpler ones out.
> + *
> + * Some devices may need to inform the backend about an address/location
> + * where to read or write the data.
I'd drop the 'location' part unless this gets used later because you
are referring register address above.
> + *
> + * RETURNS:
> + * 0 on success, negative error number on failure.
> + */
> +int iio_backend_data_transfer_addr(struct iio_backend *back, u32 address)
> +{
> + return iio_backend_op_call(back, data_transfer_addr, address);
> +}
> +EXPORT_SYMBOL_NS_GPL(iio_backend_data_transfer_addr, IIO_BACKEND);
> +
> +/**
> + * iio_backend_bus_reg_read - Read from the interface bus
> + * @back: Backend device
> + * @reg: Register valule
> + * @val: Pointer to register value
> + * @size: Size, in bytes
> + *
> + * A backend may operate on a specific interface with a related bus.
> + * Read from the interface bus.
So this is effectively routing control plane data through the offloaded
bus? That sounds a lot more like a conventional bus than IIO backend.
Perhaps it should be presented as that with the IIO device attached
to that bus? I don't fully understand what is wired up here.
> + *
> + * RETURNS:
> + * 0 on success, negative error number on failure.
> + */
> +int iio_backend_bus_reg_read(struct iio_backend *back,
> + u32 reg, void *val, size_t size)
> +{
> + if (!size)
> + return -EINVAL;
> +
> + return iio_backend_op_call(back, bus_reg_read, reg, val, size);
> +}
> +EXPORT_SYMBOL_NS_GPL(iio_backend_bus_reg_read, IIO_BACKEND);
> +
