Re: [PATCH v4 02/37] firmware: arm_scmi: introduce protocol handle definitions

[Thara Gopinath]

On 1/8/21 7:04 AM, Cristian Marussi wrote:
> Hi Thara
>
> thanks for reviewing.
>
> On Thu, Jan 07, 2021 at 09:29:17AM -0500, Thara Gopinath wrote:
> > On 1/6/21 3:15 PM, Cristian Marussi wrote:
> > > Add basic protocol handles definitions and private data helpers support.
> > >
> > > A protocol handle identifies a protocol instance initialized against a
> > > specific handle; it embeds all the references to the core SCMI xfer methods
> > > that will be needed by a protocol implementation to build and send its own
> > > protocol specific messages using common core methods.
> > >
> > > As such, in the interface, a protocol handle will be passed down from the
> > > core to the protocol specific initialization callback at init time.
> > >
> > > Anyway at this point only definitions are introduced, all protocols
> > > initialization code and SCMI drivers probing is still based on the old
> > > interface, so no functional change.
> > >
> > > Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> > > ---
> > >    drivers/firmware/arm_scmi/common.h | 59 ++++++++++++++++++++++++++++++
> > >    drivers/firmware/arm_scmi/driver.c | 45 +++++++++++++++++++++++
> > >    2 files changed, 104 insertions(+)
> > >
> > > diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
> > > index e052507dc918..977e31224efe 100644
> > > --- a/drivers/firmware/arm_scmi/common.h
> > > +++ b/drivers/firmware/arm_scmi/common.h
> > > @@ -149,6 +149,65 @@ int scmi_xfer_get_init(const struct scmi_handle *h, u8 msg_id, u8 prot_id,
> > >    		       size_t tx_size, size_t rx_size, struct scmi_xfer **p);
> > >    void scmi_reset_rx_to_maxsz(const struct scmi_handle *handle,
> > >    			    struct scmi_xfer *xfer);
> > > +
> > > +struct scmi_xfer_ops;
> > > +
> > > +/**
> > > + * struct scmi_protocol_handle  - Reference to an initialized protocol instance
> > > + *
> > > + * @dev: A reference to the associated SCMI instance device (handle->dev).
> > > + * @xops: A reference to a struct holding refs to the core xfer operations that
> > > + *	  can be used by the protocol implementation to generate SCMI messages.
> > > + * @set_priv: A method to set protocol private data for this instance.
> > > + * @get_priv: A method to get protocol private data previously set.
> > > + *
> > > + * This structure represents a protocol initialized against specific SCMI
> > > + * instance and it will be used as follows:
> > > + * - as a parameter fed from the core to the protocol initialization code so
> > > + *   that it can access the core xfer operations to build and generate SCMI
> > > + *   messages exclusively for the specific underlying protocol instance.
> > > + * - as an opaque handle fed by an SCMI driver user when it tries to access
> > > + *   this protocol through its own protocol operations.
> > > + *   In this case this handle will be returned as an opaque object together
> > > + *   with the related protocol operations when the SCMI driver tries to access
> > > + *   the protocol.
> > > + */
> > > +struct scmi_protocol_handle {
> > > +	struct device *dev;
> > > +	const struct scmi_xfer_ops *xops;
> > > +	int (*set_priv)(const struct scmi_protocol_handle *ph, void *priv);
> > > +	void *(*get_priv)(const struct scmi_protocol_handle *ph);
> > > +};
> > > +
> > > +/**
> > > + * struct scmi_xfer_ops  - References to the core SCMI xfer operations.
> > > + * @version_get: Get this version protocol.
> > > + * @xfer_get_init: Initialize one struct xfer if any xfer slot is free.
> > > + * @reset_rx_to_maxsz: Reset rx size to max transport size.
> > > + * @do_xfer: Do the SCMI transfer.
> > > + * @do_xfer_with_response: Do the SCMI transfer waiting for a response.
> > > + * @xfer_put: Free the xfer slot.
> > > + *
> > > + * Note that all this operations expect a protocol handle as first parameter;
> > > + * they then internally use it to infer the underlying protocol number: this
> > > + * way is not possible for a protocol implementation to forge messages for
> > > + * another protocol.
> > > + */
> > > +struct scmi_xfer_ops {
> >
> > Maybe move the definition above struct scmi_protocol_handle to avoid a
> > declaration ?
>
> But all the ops defined inside scmi_xfer_ops refers then to a param
> struct scmi_protocol_handle, so I'd need anyway a similar declaration
> the other way around.
>
> If not:
>
> linux/drivers/firmware/arm_scmi/common.h:178:32: warning: ‘struct scmi_protocol_handle’ declared inside parameter list will not be visible outside of this definition or declaration

Ya. got it. I had not realized this.
> Thanks
>
> Cristian
> > --
> > Warm Regards
> > Thara

--
Warm Regards
Thara