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://www.microsoft.com/en-us/download/details.aspx?id=103325. > + > +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. > +- 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? > +- 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. > +- 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. > + > +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 > >
