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. > It is possible to > add several compatible strings like "kendryte,k210-spi3". Why ? > 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 ? -- Best regards, Marek Vasut
