On 3/21/20 11:04 PM, Marek Vasut wrote: > On 3/22/20 3:36 AM, Sean Anderson wrote: >> On 3/21/20 9:51 PM, Marek Vasut wrote: >>> On 3/5/20 8:19 PM, Sean Anderson wrote: >>>> Some devices have different layouts for the fields in CTRL0 (e.g. the >>>> Kendryte K210). Allow this layout to be configurable from the device tree. >>>> The documentation has been taken from Linux. >>>> >>>> Signed-off-by: Sean Anderson <sean...@gmail.com> >>>> Reviewed-by: Simon Glass <s...@chromium.org> >>> >>> Can't you just have different compatible string for each SoC and derive >>> the various fields based on that compatible string, instead of >>> describing all the register bitfields in DT ? >>> >>> What does Linux do ? >>> >> >> Linux only supports socfpga boards. I don't know if there is any >> rhyme/reason to the shifting around of these fields. > > Could be a different revision of the IP. This is usually handled by > using SoC-specific compatible strings, see e.g. Linux > Documentation/devicetree/bindings/usb/renesas,usb3-peri.yaml > > You don't want to encode register layout in the DT.
Ok, then I think adding compatible strings would be the cleanest. > >> It is possible to >> add several compatible strings like "kendryte,k210-spi3". > > Why ? See below. > >> I chose this >> method because the bitfields are different for spi0 and spi1, spi2, and >> spi3. If there are other incompatibilities discovered, then it may make >> more sense to use different strings. Another option could have been to >> use the DW_SPI_VERSION field to detect different controllers, but it is >> the same among all the controllers on the K210. > > The controllers on the same SoC have different register layout ? > Yup! Don't ask me why. --Sean
