| Message ID | 20211028124518.17370-2-p.yadav@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add bindings for slave-specific SPI controller properties | expand |
On Thu, Oct 28, 2021 at 06:15:16PM +0530, Pratyush Yadav wrote: > Many SPI controllers need to add properties to slave devices. This could Probably should replace 'slave' with 'peripheral' throughout[1]. > be the delay in clock or data lines, etc. These properties are > controller specific but need to be defined in the slave node because > they are per-slave and there can be multiple slaves attached to a > controller. > > If these properties are not added to the slave binding, then the dtbs > check emits a warning. But these properties do not make much sense in > the slave binding because they are controller-specific and they will > just pollute every slave binding. So this binding is added to collect > all such properties from all such controllers. Slave bindings should > simply refer to this binding and they should be rid of the warnings. > > There are some limitations with this approach. Firstly, there is no way > to specify required properties. The schema contains properties for all > controllers and there is no way to know which controller is being used. > Secondly, there is no way to restrict additional properties. Since this > schema will be used with an allOf operator, additionalProperties needs > to be true. In addition, the slave schema will have to set > unevaluatedProperties: false. > > Despite these limitations, this appears to be the best solution to this > problem that doesn't involve modifying existing tools or schema specs. > > Signed-off-by: Pratyush Yadav <p.yadav@ti.com> > > --- > > Changes in v2: > - Move other subnode properties listed in spi-controller.yaml to > spi-slave-props.yaml > - Move the Cadence controller-specific properties out of > spi-slave-props.yaml. They will be added in a separate file. > - Add a reference to spi-slave-props.yaml in spi-controller.yaml. > - Update description. > > .../bindings/spi/spi-controller.yaml | 69 +------------- > .../bindings/spi/spi-slave-props.yaml | 91 +++++++++++++++++++ > 2 files changed, 93 insertions(+), 67 deletions(-) > create mode 100644 Documentation/devicetree/bindings/spi/spi-slave-props.yaml > > diff --git a/Documentation/devicetree/bindings/spi/spi-controller.yaml b/Documentation/devicetree/bindings/spi/spi-controller.yaml > index 8246891602e7..ff770657e214 100644 > --- a/Documentation/devicetree/bindings/spi/spi-controller.yaml > +++ b/Documentation/devicetree/bindings/spi/spi-controller.yaml > @@ -94,73 +94,8 @@ patternProperties: > "^.*@[0-9a-f]+$": > type: object > > - properties: > - compatible: > - description: > - Compatible of the SPI device. > - > - reg: > - minItems: 1 > - maxItems: 256 > - items: > - minimum: 0 > - maximum: 256 > - description: > - Chip select used by the device. > - > - spi-3wire: > - $ref: /schemas/types.yaml#/definitions/flag > - description: > - The device requires 3-wire mode. > - > - spi-cpha: > - $ref: /schemas/types.yaml#/definitions/flag > - description: > - The device requires shifted clock phase (CPHA) mode. > - > - spi-cpol: > - $ref: /schemas/types.yaml#/definitions/flag > - description: > - The device requires inverse clock polarity (CPOL) mode. > - > - spi-cs-high: > - $ref: /schemas/types.yaml#/definitions/flag > - description: > - The device requires the chip select active high. > - > - spi-lsb-first: > - $ref: /schemas/types.yaml#/definitions/flag > - description: > - The device requires the LSB first mode. > - > - spi-max-frequency: > - $ref: /schemas/types.yaml#/definitions/uint32 > - description: > - Maximum SPI clocking speed of the device in Hz. > - > - spi-rx-bus-width: > - description: > - Bus width to the SPI bus used for read transfers. > - If 0 is provided, then no RX will be possible on this device. > - $ref: /schemas/types.yaml#/definitions/uint32 > - enum: [0, 1, 2, 4, 8] > - default: 1 > - > - spi-rx-delay-us: > - description: > - Delay, in microseconds, after a read transfer. > - > - spi-tx-bus-width: > - description: > - Bus width to the SPI bus used for write transfers. > - If 0 is provided, then no TX will be possible on this device. > - $ref: /schemas/types.yaml#/definitions/uint32 > - enum: [0, 1, 2, 4, 8] > - default: 1 > - > - spi-tx-delay-us: > - description: > - Delay, in microseconds, after a write transfer. > + allOf: > + - $ref: spi-slave-props.yaml > > required: > - compatible > diff --git a/Documentation/devicetree/bindings/spi/spi-slave-props.yaml b/Documentation/devicetree/bindings/spi/spi-slave-props.yaml > new file mode 100644 > index 000000000000..5166ec9b0353 > --- /dev/null > +++ b/Documentation/devicetree/bindings/spi/spi-slave-props.yaml > @@ -0,0 +1,91 @@ > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/spi/spi-slave-props.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Slave-specific properties for a SPI bus. > + > +description: | Don't need '|' if no formatting to preserve. > + Many SPI controllers need to add properties to slave devices. They could be > + common properties like spi-max-frequency, spi-cpha, etc. or they could be > + controller specific like delay in clock or data lines, etc. These properties > + need to be defined in the slave node because they are per-slave and there can > + be multiple slaves attached to a controller. All those properties are listed > + here. The controller specific properties should go in their own separate > + schema that should be referenced from here. > + > +maintainers: > + - Pratyush Yadav <p.yadav@ti.com> > + > +properties: > + compatible: > + description: > + Compatible of the SPI device. You can drop 'compatible'. > + > + reg: > + minItems: 1 > + maxItems: 256 > + items: > + minimum: 0 > + maximum: 256 > + description: > + Chip select used by the device. > + > + spi-3wire: > + $ref: /schemas/types.yaml#/definitions/flag > + description: > + The device requires 3-wire mode. > + > + spi-cpha: > + $ref: /schemas/types.yaml#/definitions/flag > + description: > + The device requires shifted clock phase (CPHA) mode. > + > + spi-cpol: > + $ref: /schemas/types.yaml#/definitions/flag > + description: > + The device requires inverse clock polarity (CPOL) mode. > + > + spi-cs-high: > + $ref: /schemas/types.yaml#/definitions/flag > + description: > + The device requires the chip select active high. > + > + spi-lsb-first: > + $ref: /schemas/types.yaml#/definitions/flag > + description: > + The device requires the LSB first mode. > + > + spi-max-frequency: > + $ref: /schemas/types.yaml#/definitions/uint32 > + description: > + Maximum SPI clocking speed of the device in Hz. > + > + spi-rx-bus-width: > + description: > + Bus width to the SPI bus used for read transfers. > + If 0 is provided, then no RX will be possible on this device. > + $ref: /schemas/types.yaml#/definitions/uint32 > + enum: [0, 1, 2, 4, 8] > + default: 1 > + > + spi-rx-delay-us: > + description: > + Delay, in microseconds, after a read transfer. > + > + spi-tx-bus-width: > + description: > + Bus width to the SPI bus used for write transfers. > + If 0 is provided, then no TX will be possible on this device. > + $ref: /schemas/types.yaml#/definitions/uint32 > + enum: [0, 1, 2, 4, 8] > + default: 1 > + > + spi-tx-delay-us: > + description: > + Delay, in microseconds, after a write transfer. > + > +# The controller specific properties go here. > + > +additionalProperties: true > -- > 2.33.1.835.ge9e5ba39a7 > >
On Mon, Nov 08, 2021 at 12:04:55PM -0600, Rob Herring wrote: > On Thu, Oct 28, 2021 at 06:15:16PM +0530, Pratyush Yadav wrote: > > Many SPI controllers need to add properties to slave devices. This could > > Probably should replace 'slave' with 'peripheral' throughout[1]. Forgot the link: https://www.oshwa.org/a-resolution-to-redefine-spi-signal-names/
diff --git a/Documentation/devicetree/bindings/spi/spi-controller.yaml b/Documentation/devicetree/bindings/spi/spi-controller.yaml index 8246891602e7..ff770657e214 100644 --- a/Documentation/devicetree/bindings/spi/spi-controller.yaml +++ b/Documentation/devicetree/bindings/spi/spi-controller.yaml @@ -94,73 +94,8 @@ patternProperties: "^.*@[0-9a-f]+$": type: object - properties: - compatible: - description: - Compatible of the SPI device. - - reg: - minItems: 1 - maxItems: 256 - items: - minimum: 0 - maximum: 256 - description: - Chip select used by the device. - - spi-3wire: - $ref: /schemas/types.yaml#/definitions/flag - description: - The device requires 3-wire mode. - - spi-cpha: - $ref: /schemas/types.yaml#/definitions/flag - description: - The device requires shifted clock phase (CPHA) mode. - - spi-cpol: - $ref: /schemas/types.yaml#/definitions/flag - description: - The device requires inverse clock polarity (CPOL) mode. - - spi-cs-high: - $ref: /schemas/types.yaml#/definitions/flag - description: - The device requires the chip select active high. - - spi-lsb-first: - $ref: /schemas/types.yaml#/definitions/flag - description: - The device requires the LSB first mode. - - spi-max-frequency: - $ref: /schemas/types.yaml#/definitions/uint32 - description: - Maximum SPI clocking speed of the device in Hz. - - spi-rx-bus-width: - description: - Bus width to the SPI bus used for read transfers. - If 0 is provided, then no RX will be possible on this device. - $ref: /schemas/types.yaml#/definitions/uint32 - enum: [0, 1, 2, 4, 8] - default: 1 - - spi-rx-delay-us: - description: - Delay, in microseconds, after a read transfer. - - spi-tx-bus-width: - description: - Bus width to the SPI bus used for write transfers. - If 0 is provided, then no TX will be possible on this device. - $ref: /schemas/types.yaml#/definitions/uint32 - enum: [0, 1, 2, 4, 8] - default: 1 - - spi-tx-delay-us: - description: - Delay, in microseconds, after a write transfer. + allOf: + - $ref: spi-slave-props.yaml required: - compatible diff --git a/Documentation/devicetree/bindings/spi/spi-slave-props.yaml b/Documentation/devicetree/bindings/spi/spi-slave-props.yaml new file mode 100644 index 000000000000..5166ec9b0353 --- /dev/null +++ b/Documentation/devicetree/bindings/spi/spi-slave-props.yaml @@ -0,0 +1,91 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/spi/spi-slave-props.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Slave-specific properties for a SPI bus. + +description: | + Many SPI controllers need to add properties to slave devices. They could be + common properties like spi-max-frequency, spi-cpha, etc. or they could be + controller specific like delay in clock or data lines, etc. These properties + need to be defined in the slave node because they are per-slave and there can + be multiple slaves attached to a controller. All those properties are listed + here. The controller specific properties should go in their own separate + schema that should be referenced from here. + +maintainers: + - Pratyush Yadav <p.yadav@ti.com> + +properties: + compatible: + description: + Compatible of the SPI device. + + reg: + minItems: 1 + maxItems: 256 + items: + minimum: 0 + maximum: 256 + description: + Chip select used by the device. + + spi-3wire: + $ref: /schemas/types.yaml#/definitions/flag + description: + The device requires 3-wire mode. + + spi-cpha: + $ref: /schemas/types.yaml#/definitions/flag + description: + The device requires shifted clock phase (CPHA) mode. + + spi-cpol: + $ref: /schemas/types.yaml#/definitions/flag + description: + The device requires inverse clock polarity (CPOL) mode. + + spi-cs-high: + $ref: /schemas/types.yaml#/definitions/flag + description: + The device requires the chip select active high. + + spi-lsb-first: + $ref: /schemas/types.yaml#/definitions/flag + description: + The device requires the LSB first mode. + + spi-max-frequency: + $ref: /schemas/types.yaml#/definitions/uint32 + description: + Maximum SPI clocking speed of the device in Hz. + + spi-rx-bus-width: + description: + Bus width to the SPI bus used for read transfers. + If 0 is provided, then no RX will be possible on this device. + $ref: /schemas/types.yaml#/definitions/uint32 + enum: [0, 1, 2, 4, 8] + default: 1 + + spi-rx-delay-us: + description: + Delay, in microseconds, after a read transfer. + + spi-tx-bus-width: + description: + Bus width to the SPI bus used for write transfers. + If 0 is provided, then no TX will be possible on this device. + $ref: /schemas/types.yaml#/definitions/uint32 + enum: [0, 1, 2, 4, 8] + default: 1 + + spi-tx-delay-us: + description: + Delay, in microseconds, after a write transfer. + +# The controller specific properties go here. + +additionalProperties: true
Many SPI controllers need to add properties to slave devices. This could be the delay in clock or data lines, etc. These properties are controller specific but need to be defined in the slave node because they are per-slave and there can be multiple slaves attached to a controller. If these properties are not added to the slave binding, then the dtbs check emits a warning. But these properties do not make much sense in the slave binding because they are controller-specific and they will just pollute every slave binding. So this binding is added to collect all such properties from all such controllers. Slave bindings should simply refer to this binding and they should be rid of the warnings. There are some limitations with this approach. Firstly, there is no way to specify required properties. The schema contains properties for all controllers and there is no way to know which controller is being used. Secondly, there is no way to restrict additional properties. Since this schema will be used with an allOf operator, additionalProperties needs to be true. In addition, the slave schema will have to set unevaluatedProperties: false. Despite these limitations, this appears to be the best solution to this problem that doesn't involve modifying existing tools or schema specs. Signed-off-by: Pratyush Yadav <p.yadav@ti.com> --- Changes in v2: - Move other subnode properties listed in spi-controller.yaml to spi-slave-props.yaml - Move the Cadence controller-specific properties out of spi-slave-props.yaml. They will be added in a separate file. - Add a reference to spi-slave-props.yaml in spi-controller.yaml. - Update description. .../bindings/spi/spi-controller.yaml | 69 +------------- .../bindings/spi/spi-slave-props.yaml | 91 +++++++++++++++++++ 2 files changed, 93 insertions(+), 67 deletions(-) create mode 100644 Documentation/devicetree/bindings/spi/spi-slave-props.yaml