Hi Corey, On Fri, 19 Mar 2021, at 16:49, Andrew Jeffery wrote: > Hello, > > This series is a bit of a mix of things, but its primary purpose is to > expose BMC KCS IPMI devices to userspace in a way that enables userspace > to talk to host firmware using protocols that are not IPMI. > > v1 can be found here: > > https://lore.kernel.org/openbmc/20210219142523.3464540-1-andrew@xxxxxxxx/ > > Changes in v2 include: > > * A rebase onto v5.12-rc2 > * Incorporation of off-list feedback on SerIRQ configuration from > Chiawei > * Further validation on hardware for ASPEED KCS devices 2, 3 and 4 > * Lifting the existing single-open constraint of the IPMI chardev > * Fixes addressing Rob's feedback on the conversion of the ASPEED KCS > binding to dt-schema > * Fixes addressing Rob's feedback on the new aspeed,lpc-interrupts > property definition for the ASPEED KCS binding > > A new chardev device is added whose implementation exposes the Input > Data Register (IDR), Output Data Register (ODR) and Status Register > (STR) via read() and write(), and implements poll() for event > monitoring. > > The existing /dev/ipmi-kcs* chardev interface exposes the KCS devices in > a way which encoded the IPMI protocol in its behaviour. However, as > LPC[0] KCS devices give us bi-directional interrupts between the host > and a BMC with both a data and status byte, they are useful for purposes > beyond IPMI. > > As a concrete example, libmctp[1] implements a vendor-defined MCTP[2] > binding using a combination of LPC Firmware cycles for bulk data > transfer and a KCS device via LPC IO cycles for out-of-band protocol > control messages[3]. This gives a throughput improvement over the > standard KCS binding[4] while continuing to exploit the ease of setup of > the LPC bus for early boot firmware on the host processor. > > The series takes a bit of a winding path to achieve its aim: > > 1. It begins with patches 1-5 put together by Chia-Wei, which I've > rebased on v5.12-rc2. These fix the ASPEED LPC bindings and other > non-KCS LPC-related ASPEED device drivers in a way that enables the > SerIRQ patches at the end of the series. With Joel's review I'm hoping > these 5 can go through the aspeed tree, and that the rest can go through > the IPMI tree. > > 2. Next, patches 6-13 fairly heavily refactor the KCS support in the > IPMI part of the tree, re-architecting things such that it's possible to > support multiple chardev implementations sitting on top of the ASPEED > and Nuvoton device drivers. However, the KCS code didn't really have > great separation of concerns as it stood, so even if we disregard the > multiple-chardev support I think the cleanups are worthwhile. > > 3. Patch 14 adds some interrupt management capabilities to the KCS > device drivers in preparation for patch 16, which introduces the new > "raw" KCS device interface. I'm not stoked about the device name/path, > so if people are looking to bikeshed something then feel free to lay > into that. > > 4. The remaining patches switch the ASPEED KCS devicetree binding to > dt-schema, add a new interrupt property to describe the SerIRQ behaviour > of the device and finally clean up Serial IRQ support in the ASPEED KCS > driver. > > Rob: The dt-binding patches still come before the relevant driver > changes, I tried to keep the two close together in the series, hence the > bindings changes not being patches 1 and 2. > > I've exercised the series under qemu with the rainier-bmc machine plus > additional patches for KCS support[5]. I've also substituted this series in > place of a hacky out-of-tree driver that we've been using for the > libmctp stack and successfully booted the host processor under our > internal full-platform simulation tools for a Rainier system. > > Note that this work touches the Nuvoton driver as well as ASPEED's, but > I don't have the capability to test those changes or the IPMI chardev > path. Tested-by tags would be much appreciated if you can exercise one > or both. > > Please review! Unfortunately the cover letter got detached from the rest of the series. Any chance you can take a look at the patches? https://lore.kernel.org/linux-arm-kernel/20210319062752.145730-1-andrew@xxxxxxxx/ Cheers, Andrew
