Re: [PATCH v4 3/4] fpga: dfl: add basic support DFHv1

Ilpo Järvinen
2022-10-21T09:08:11Z

On Thu, 20 Oct 2022, matthew.gerlach@linux.intel.com wrote:

> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>
> Add generic support for MSI-X interrupts for DFL devices.
>
> The location of a feature's registers is explicitly
> described in DFHv1 and can be relative to the base of the DFHv1
> or an absolute address. Parse the location and pass the information
> to DFL driver.
>
> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> ---

> @@ -934,56 +962,108 @@ static u16 feature_id(u64 value)
> return 0;
> }
>
> +static void *find_param(void *base, resource_size_t max, int param)
> +{
> + int off = 0;
> + u64 v, next;
> +
> + while (off < max) {
> + v = *(u64 *)(base + off);
> + if (param == FIELD_GET(DFHv1_PARAM_HDR_ID, v))
> + return base + off + DFHv1_PARAM_DATA;
> +
> + next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v);
> + off += next & ~DFHv1_PARAM_HDR_NEXT_MASK;
> + if (next & DFHv1_PARAM_HDR_NEXT_EOL)
> + break;
> +
> + }
> +
> + return NULL;
> +}
> +
> +/**
> + * dfh_find_param() - find data for the given parameter id
> + * @dfl_dev: dfl device
> + * @param: id of dfl parameter
> + *
> + * Return: pointer to parameter data on success, NULL otherwise.
> + */
> +void *dfh_find_param(struct dfl_device *dfl_dev, int param)
> +{
> + return find_param(dfl_dev->params, dfl_dev->param_size, param);
> +}
> +EXPORT_SYMBOL_GPL(dfh_find_param);

Do you expect this split between dfh_find_param() and find_param() to
be useful in the future? If no other callers are expected, I'd just pull
find_param() into dfh_find_param() and create local variables for base and
max.

--
i.