Hello Rob, I just submitted patch v4 that addresses most of your feedback. On Thu, Jan 20, 2022 at 12:07 PM,Rob Herring wrote: > From: Rob Herring <robh@xxxxxxxxxx> > > On Fri, Jan 14, 2022 at 06:31:33PM -0800, Dmitry Antipov wrote: > > From: Dmitry Antipov <dmanti@xxxxxxxxxxxxx> > > > > Added documentation describes the required properties for implementing > > Device Tree for a device supporting HID over SPI and also provides an > > example. > > Bindings are in DT schema format now. > > > > > Signed-off-by: Dmitry Antipov <dmanti@xxxxxxxxxxxxx> > > --- > > .../bindings/input/hid-over-spi.txt | 43 +++++++++++++++++++ > > 1 file changed, 43 insertions(+) > > create mode 100755 > > Documentation/devicetree/bindings/input/hid-over-spi.txt > > > > diff --git a/Documentation/devicetree/bindings/input/hid-over-spi.txt > > b/Documentation/devicetree/bindings/input/hid-over-spi.txt > > new file mode 100755 > > index 000000000000..5eba95b5724e > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/input/hid-over-spi.txt > > @@ -0,0 +1,43 @@ > > +* HID over SPI Device-Tree bindings > > + > > +HID over SPI provides support for Human Interface Devices over the > > +SPI bus. HID Over SPI Protocol Specification 1.0 was written by > > +Microsoft and is available at > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.m > icrosoft.com%2Fen- > us%2Fdownload%2Fdetails.aspx%3Fid%3D103325&data=04%7C01%7Cd > manti%40microsoft.com%7Cb0b84680fa2c45bc2f3a08d9dc5063f6%7C72f988 > bf86f141af91ab2d7cd011db47%7C1%7C0%7C637783060144589082%7CUnkn > own%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1h > aWwiLCJXVCI6Mn0%3D%7C3000&sdata=bWGZDRYtVovy3XYlpDsZ8xR2AL > be5YoP0iSZ8xORSyA%3D&reserved=0. > > + > > +If this binding is used, the kernel module spi-hid will handle the > > +communication > > What's a kernel module? ;) Bindings are OS independent (or supposed to be), so > kernel details do not belong here. > > > +with the device and the generic hid core layer will handle the protocol. > > + > > +Required properties: > > +- compatible: must be "hid-over-spi" > > Bindings describe devices, not protocols. There is no such 'hid-over-spi' device. > Please see the existing hid-over-i2c binding. > It's fine to have this compatible, but only as a fallback compatible. In the v4 patch the yaml file expects the device-specific compatible string, but also 'hid-over-spi'. > > > +- interrupts: interrupt line > > +- vdd-supply: phandle of the regulator that provides the supply > > +voltage > > What happens when the device has 2 supplies? And there's some timing > requirement between them? I am not sure if there is a way to account for all possible scenarios. Our device only has one power regulator and the binding is now device-specific. > > > +- reset_gpio-gpios: gpio wired to the device reset line > > 'reset-gpios' is the standard name. > > > +- post-power-on-delay-ms: time required by the device after enabling > > +its regulators or powering it on, before it is ready for > > +communication > > +- minimal-reset-delay-ms: minimum amount of time that device needs to > > +be in reset state for the reset to take effect > > These properties are what happens when we try to do generic bindings. > It's a never-ending addition of more properties to try to describe > (poorly) the power sequencing requirements. I have made these optional in the v4 patch. > > > +- input-report-header-address: this property and the rest are > > +described in HID Over SPI Protocol Spec 1.0 > > +- input-report-body-address > > +- output-report-address > > +- read-opcode > > +- write-opcode > > +- flags > > A bit too generic. We generally want to avoid having a property name with 2 > different types/meaning. It's not something we check for yet, but I plan to at > some point. I've made "flags" more specific in the v4 patch. > > > + > > +Example: > > + spi-hid-dev0 { > > + compatible = "hid-over-spi"; > > + reg = <0>; > > + interrupts-extended = <&tlmm 42 IRQ_TYPE_EDGE_FALLING>; > > + vdd-supply = <&pm8350c_l3>; > > + input-report-header-address = <0x1000>; > > + input-report-body-address = <0x1004>; > > + output-report-address = <0x2000>; > > + read-opcode = <0x0b>; > > + write-opcode = <0x02>; > > + flags = <0x00>; > > + reset_gpio-gpios = <&tlmm 25 GPIO_ACTIVE_LOW>; > > + post-power-on-delay-ms = <5>; > > + minimal-reset-delay-ms = <5>; > > + > > + }; > > -- > > 2.25.1 > > > >
