Hi, > -----Original Message----- > From: Sam Protsenko <semen.protsenko@xxxxxxxxxx> > Sent: Sunday, December 5, 2021 4:58 AM > To: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx>; Rob Herring > <robh+dt@xxxxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: Jaewon Kim <jaewon02.kim@xxxxxxxxxxx>; Chanho Park > <chanho61.park@xxxxxxxxxxx>; David Virag <virag.david003@xxxxxxxxx>; > Youngmin Nam <youngmin.nam@xxxxxxxxxxx>; devicetree@xxxxxxxxxxxxxxx; > linux-serial@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; linux-samsung-soc@xxxxxxxxxxxxxxx > Subject: [PATCH v3 0/5] soc: samsung: Add USI driver > > 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 Tested-by: Chanho Park <chanho61.park@xxxxxxxxxxx> with below patch. https://lore.kernel.org/linux-samsung-soc/20211208003946.139423-1-chanho61.p ark@xxxxxxxxxxx/T/#u Thanks. Best Regards, Chanho Park
