On Fri, Dec 3, 2021 at 1:36 PM Sam Protsenko <semen.protsenko@xxxxxxxxxx> wrote: > > On Tue, 30 Nov 2021 at 21:31, Rob Herring <robh@xxxxxxxxxx> wrote: > > > > On Tue, Nov 30, 2021 at 01:13:21PM +0200, Sam Protsenko wrote: > > > Add constants for choosing USIv2 configuration mode in device tree. > > > Those are further used in USI driver to figure out which value to write > > > into SW_CONF register. Also document USIv2 IP-core bindings. > > > > > > Signed-off-by: Sam Protsenko <semen.protsenko@xxxxxxxxxx> > > > --- > > > Changes in v2: > > > - Combined dt-bindings doc and dt-bindings header patches > > > - Added i2c node to example in bindings doc > > > - Added mentioning of shared internal circuits > > > - Added USI_V2_NONE value to bindings header > > > > > > .../bindings/soc/samsung/exynos-usi.yaml | 135 ++++++++++++++++++ > > > include/dt-bindings/soc/samsung,exynos-usi.h | 17 +++ > > > 2 files changed, 152 insertions(+) > > > create mode 100644 Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml > > > create mode 100644 include/dt-bindings/soc/samsung,exynos-usi.h > > > > > > diff --git a/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml b/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml > > > new file mode 100644 > > > index 000000000000..a822bc62b3cd > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml > > > @@ -0,0 +1,135 @@ > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > > > +%YAML 1.2 > > > +--- > > > +$id: http://devicetree.org/schemas/soc/samsung/exynos-usi.yaml# > > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > > + > > > +title: Samsung's Exynos USI (Universal Serial Interface) binding > > > + > > > +maintainers: > > > + - Sam Protsenko <semen.protsenko@xxxxxxxxxx> > > > + - Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx> > > > + > > > +description: | > > > + USI IP-core provides selectable serial protocol (UART, SPI or High-Speed I2C). > > > + USI shares almost all internal circuits within each protocol, so only one > > > + protocol can be chosen at a time. USI is modeled as a node with zero or more > > > + child nodes, each representing a serial sub-node device. The mode setting > > > + selects which particular function will be used. > > > + > > > + Refer to next bindings documentation for information on protocol subnodes that > > > + can exist under USI node: > > > + > > > + [1] Documentation/devicetree/bindings/serial/samsung_uart.yaml > > > + [2] Documentation/devicetree/bindings/i2c/i2c-exynos5.txt > > > + [3] Documentation/devicetree/bindings/spi/spi-samsung.txt > > > + > > > +properties: > > > + $nodename: > > > + pattern: "^usi@[0-9a-f]+$" > > > + > > > + compatible: > > > + const: samsung,exynos-usi-v2 > > > > Use SoC based compatibles. > > > > In this particular case, I'd really prefer to have it like this. Most > likely we'll only have USIv1 and USIv1 in the end, and I think that > would be more clear to have USI version in compatible, rather than SoC > name. Please let me know if you have a strong opinion on this one -- > if so I'll re-send. Fine if you have some evidence the ratio of versions to SoC are much more than 1:1 and the versions correspond to something (IOW, you aren't making them up). We went down the version # path with QCom and in the end about every SoC had a different version. > > > > + > > > + reg: > > > + maxItems: 1 > > > + > > > + clocks: > > > + items: > > > + - description: Bus (APB) clock > > > + - description: Operating clock for UART/SPI/I2C protocol > > > + > > > + clock-names: > > > + items: > > > + - const: pclk > > > + - const: ipclk > > > + > > > + ranges: true > > > + > > > + "#address-cells": > > > + const: 1 > > > + > > > + "#size-cells": > > > + const: 1 > > > + > > > + samsung,sysreg: > > > + $ref: /schemas/types.yaml#/definitions/phandle-array > > > + description: > > > + Should be phandle/offset pair. The phandle to System Register syscon node > > > + (for the same domain where this USI controller resides) and the offset > > > + of SW_CONF register for this USI controller. > > > + > > > + samsung,mode: > > > + $ref: /schemas/types.yaml#/definitions/uint32 > > > + description: > > > + Selects USI function (which serial protocol to use). Refer to > > > + <include/dt-bindings/soc/samsung,exynos-usi.h> for valid USI mode values. > > > > This seems to be redundant. Just check which child is enabled. > > > > I think it's not that easy. Soon we'll have USIv1 support added, and > that has some weird configurations, like having dual I2C mode (two > child I2C nodes must be enabled) and UART+I2C mode, etc. So you are going to turn around and make this an array? If you already know you have changes, I'd rather review this all at once. > Looks like it > might take some not very elegant logic to figure out which exactly > mode value should be written in SW_CONF register in that way, it's > much easier to just specify mode in USI node. Also, that reflects > hardware better: we actually write that specified mode to SW_CONF > register. You just have to compare the child node names or compatibles. > Also, later we might want to be able to switch that mode via > SysFS, e.g. for testing purposes. Current design seems to be better > suited for some things like that. The binding should have no impact on that. If for testing, use debugfs. > Please let me know if you have a strong opinion on this one, or it's > ok to leave it as is. > > All other comments are addressed and will be present in v3. Thanks for > the review!
