On 04/12/2021 20:57, Sam Protsenko wrote: > USIv2 IP-core provides selectable serial protocol (UART, SPI or > High-Speed I2C); only one can be chosen at a time. This series > implements USIv2 driver, which allows one to select particular USI > function in device tree, and also performs USI block initialization. > > With that driver implemented, it's not needed to do USI initialization > in protocol drivers anymore, so that code is removed from the serial > driver. > > Because USI driver is tristate (can be built as a module), serial driver > was reworked so it's possible to use its console part as a module too. > This way we can load serial driver module from user space and still have > serial console functional. > > Design features: > - "reg" property contains USI registers start address (0xc0 offset); > it's used in the driver to access USI_CON and USI_OPTION registers. > This way all USI initialization (reset, HWACG, etc) can be done in > USIv2 driver separately, rather than duplicating that code over > UART/SPI/I2C drivers > - System Register (system controller node) and its SW_CONF register > offset are provided in "samsung,sysreg" property; it's used to > select USI function (protocol to be used) > - USI function is specified in "samsung,mode" property; integer value > is used to simplify parsing > - there is "samsung,clkreq-on" bool property, which makes driver > disable HWACG control (needed for UART to work properly) > - PCLK and IPCLK clocks are both provided to USI node; apparently both > need to be enabled to access USI registers > - protocol nodes are embedded (as a child nodes) in USI node; it > allows correct init order, and reflects HW properly > - USI driver is a tristate: can be also useful from Android GKI > requirements point of view > - driver functions are implemented with further development in mind: > - we might want to add some DebugFs interface later > - some functions might need to be revealed to serial drivers with > EXPORT_SYMBOL(), and provide somehow pointer to needed USI driver > instance > - another USI revisions could be added (like USIv1) > > Changes in v3: > - Renamed compatible from samsung,exynos-usi-v2 to samsung,exynos850-usi > - Used clk_bulk API instead of handling each clock separately > - Spell check fixes and coding style fixes > - Improved dt-bindings doc > > Changes in v2: > - Renamed all 'usi_v2' wording to just 'usi' everywhere > - Removed patches adding dependency on EXYNOS_USI for UART/I2C/SPI > drivers > - Added patch: "tty: serial: samsung: Fix console registration from > module" > - Combined dt-bindings doc and dt-bindings header patches > - Reworked USI driver to be ready for USIv1 addition > - Improved dt-bindings > - Added USI_V2_NONE mode value > > Sam Protsenko (5): > dt-bindings: soc: samsung: Add Exynos USI bindings > soc: samsung: Add USI driver > tty: serial: samsung: Remove USI initialization > tty: serial: samsung: Enable console as module > tty: serial: samsung: Fix console registration from module > All this looks good to me. The serial driver changes should come together with this one (usi driver is now a dependency for them). If I am correct, mention this please in future cover letter (if there is such). I will still need DTSI changes for Exynos Auto v9 and confirmation that is not being used downstream and breaking DTB ABI is okay. Because this will be a non-bisctable and also a DTB ABI break. Best regards, Krzysztof
