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We chose a dedicated bus_type for the reasons described above >>>      (capability negotiation, four independent channels, asynchronous >>>      ALERT#). Does the community agree this is the right direction, or >>>      is there a strong preference to extend the SPI subsystem instead? >> >> That's up to the SPI maintainers and developers... > > There's concurrent discussion from YH regarding device-side eSPI > support in the thread ending here: > > https://lore.kernel.org/all/KL1PR0601MB4276FA2C6347192CC45826E490ED2@KL1PR0601MB4276.apcprd06.prod.outlook.com/ > > So far it's arrived at a matching proposal for drivers/espi. Thank you for the introduction and for pointing to YH Chung's work. It is encouraging to see concurrent work arriving at a similar framework structure for drivers/espi — this gives us more confidence that the proposed design is on the right track. > >> >>>   3. Any concerns with the ops table design or the -EOPNOTSUPP fallback? >>>   4. Naming and structure of the public API in include/linux/espi/espi.h. >> >> What specifically are you asking for for this?  Do you have userspace >> code you want to integrate, if so, does it work with this?  And where >> does it live? > > I've seen your follow-up realisation Greg, however, regarding > userspace, the thread above suggests that we should be able to back > existing subsystems (GPIO for VW, MCTP for OOB, MTD for some flash > functionality) onto eSPI to minimise eSPI-specific interfaces: > > https://lore.kernel.org/all/KL1PR0601MB4276B5BE3B96C18E3A66AD709049A@KL1PR0601MB4276.apcprd06.prod.outlook.com/ > > That doesn't cover the peripheral channel, as that's dealt with in > hardware on the device side, but for the purpose of the controller the > devices on the peripheral channel should all be driven by the kernel > anyway. > I will go through YH Chung's complete thread on device-side eSPI support to understand the full picture. Reusing existing well-established kernel subsystems (GPIO for VWire, MCTP for OOB, MTD for Flash) to minimize eSPI-specific userspace interfaces is a sound direction. YH Chung, would you be open to collaborating on the slave-side interfaces of the new eSPI framework? Happy to discuss further on the list or off-list to align on the design before the next revision. Thanks, Krishna > Andrew