On 2023-01-04 at 15:22:52 -0800, matthew.gerlach@xxxxxxxxxxxxxxx wrote:
> From: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
>
> Version 1 of the Device Feature Header (DFH) definition adds
> functionality to the Device Feature List (DFL) bus.
>
> A DFHv1 header may have one or more parameter blocks that
> further describes the HW to SW. Add support to the DFL bus
> to parse the MSI-X parameter.
>
> The location of a feature's register set 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@xxxxxxxxxxxxxxx>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
>
[...]
> +static u64 *find_param(u64 *params, resource_size_t max, int param_id)
> +{
> + u64 *end = params + max / sizeof(u64);
> + u64 v, next;
> +
> + while (params < end) {
> + v = *params;
> + if (param_id == FIELD_GET(DFHv1_PARAM_HDR_ID, v))
> + return params;
> +
> + if (FIELD_GET(DFHv1_PARAM_HDR_NEXT_EOP, v))
> + break;
> +
> + next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v);
> + params += next;
> + }
> +
> + return NULL;
> +}
> +
> +/**
> + * dfh_find_param() - find parameter block for the given parameter id
> + * @dfl_dev: dfl device
> + * @param_id: id of dfl parameter
> + * @pcount: destination to store size of parameter data in u64 bit words
As I mentioned before, could the size of the parameter data just be number
of bytes? This is the most common way for a data block.
Thanks,
Yilun
> + *
> + * Return: pointer to start of parameter data, PTR_ERR otherwise.
> + */
> +void *dfh_find_param(struct dfl_device *dfl_dev, int param_id, size_t *pcount)
> +{
> + u64 *phdr = find_param(dfl_dev->params, dfl_dev->param_size, param_id);
> +
> + if (!phdr)
> + return ERR_PTR(-ENOENT);
> +
> + if (pcount)
> + *pcount = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, *phdr) - 1;
> +
> + return phdr + 1;
> +}
> +EXPORT_SYMBOL_GPL(dfh_find_param);
