Re: [PATCH RFC] firmware: arm_scmi: Allow for better protocol extensibility

[Florian Fainelli]

On 5/21/19 1:01 PM, Florian Fainelli wrote:
> The SCMI specific allows implementors to define their custom protocols
> in the 0x80-0xFF space. The current scmi_handle structure requires us to
> extend the structure with a set of operations and associated private
> data in a way that is not quite scaling well.
> 
> Create a 255 bytes structure that contains an opaque pointer to a set of
> operations and private data and create two helper functions to retrieve
> those based on the protocol identifier. Several options were considered,
> like using a linked list but since we could be performance sensitive in
> some paths, using an array was faster and simpler.
> 
> Convert all call sites to use either scmi_protocol_get_ops() or
> scmi_protocol_get_info().
> 
> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>

On second thought, what I really need is private storage to the scmi_dev
(the consumer side), and not so much the protocol (provider) side.
Therefore using dev_{set,get}_drvadata() against scmi_device::dev should
be working just fine, and if we are concerned about another part of the
SCMI stack making use of that storage, we can always extend struct
scmi_device with a private cookie.
-- 
Florian