| Message ID | 1493919951-32122-2-git-send-email-geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | a8830cb19cfea04edb0381b52fd90eec44986eb9 |
| Headers | show |
On Thu, May 04, 2017 at 07:45:46PM +0200, Geert Uytterhoeven wrote: > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > --- > v3: > - In SPI slave mode, represent the (single) slave device again as a > child of the controller node, which is now optional, and must be > named "slave" if present, > - Split slave node properties in master mode, slave mode, and common > properties, > > v2: > - Do not create a child node in SPI slave mode. Instead, add an > "spi-slave" property, and put the mode properties in the controller > node. > --- > Documentation/devicetree/bindings/spi/spi-bus.txt | 76 ++++++++++++++--------- > 1 file changed, 45 insertions(+), 31 deletions(-) > > diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt > index 4b1d6e74c744fe96..1f6e86f787efd229 100644 > --- a/Documentation/devicetree/bindings/spi/spi-bus.txt > +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt > @@ -1,17 +1,23 @@ > SPI (Serial Peripheral Interface) busses > > -SPI busses can be described with a node for the SPI master device > -and a set of child nodes for each SPI slave on the bus. For this > -discussion, it is assumed that the system's SPI controller is in > -SPI master mode. This binding does not describe SPI controllers > -in slave mode. > +SPI busses can be described with a node for the SPI controller device > +and a set of child nodes for each SPI slave on the bus. The system's SPI > +controller may be described for use in SPI master mode or in SPI slave mode, > +but not for both at the same time. > > -The SPI master node requires the following properties: > +The SPI controller node requires the following properties: > +- compatible - Name of SPI bus controller following generic names > + recommended practice. > + > +In master mode, the SPI controller node requires the following additional > +properties: > - #address-cells - number of cells required to define a chip select > address on the SPI bus. > - #size-cells - should be zero. > -- compatible - name of SPI bus controller following generic names > - recommended practice. > + > +In slave mode, the SPI controller node requires one additional property: > +- spi-slave - Empty property. Do we still need this if we have a child node called "slave". Otherwise, Reviewed-by: Rob Herring <robh@kernel.org> -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Rob, On Mon, May 8, 2017 at 6:55 PM, Rob Herring <robh@kernel.org> wrote: > On Thu, May 04, 2017 at 07:45:46PM +0200, Geert Uytterhoeven wrote: >> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> >> --- >> v3: >> - In SPI slave mode, represent the (single) slave device again as a >> child of the controller node, which is now optional, and must be >> named "slave" if present, >> - Split slave node properties in master mode, slave mode, and common >> properties, >> >> v2: >> - Do not create a child node in SPI slave mode. Instead, add an >> "spi-slave" property, and put the mode properties in the controller >> node. >> --- a/Documentation/devicetree/bindings/spi/spi-bus.txt >> +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt >> +In slave mode, the SPI controller node requires one additional property: >> +- spi-slave - Empty property. > > Do we still need this if we have a child node called "slave". Yes, as the child node called "slave" is optional. In that case, configuration of the slave protocol is done through sysfs, but that is Linux-specific and thus doesn't belong in the DT bindings. > Otherwise, > > Reviewed-by: Rob Herring <robh@kernel.org> Thank you! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt index 4b1d6e74c744fe96..1f6e86f787efd229 100644 --- a/Documentation/devicetree/bindings/spi/spi-bus.txt +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt @@ -1,17 +1,23 @@ SPI (Serial Peripheral Interface) busses -SPI busses can be described with a node for the SPI master device -and a set of child nodes for each SPI slave on the bus. For this -discussion, it is assumed that the system's SPI controller is in -SPI master mode. This binding does not describe SPI controllers -in slave mode. +SPI busses can be described with a node for the SPI controller device +and a set of child nodes for each SPI slave on the bus. The system's SPI +controller may be described for use in SPI master mode or in SPI slave mode, +but not for both at the same time. -The SPI master node requires the following properties: +The SPI controller node requires the following properties: +- compatible - Name of SPI bus controller following generic names + recommended practice. + +In master mode, the SPI controller node requires the following additional +properties: - #address-cells - number of cells required to define a chip select address on the SPI bus. - #size-cells - should be zero. -- compatible - name of SPI bus controller following generic names - recommended practice. + +In slave mode, the SPI controller node requires one additional property: +- spi-slave - Empty property. + No other properties are required in the SPI bus node. It is assumed that a driver for an SPI bus device will understand that it is an SPI bus. However, the binding does not attempt to define the specific method for @@ -21,7 +27,7 @@ assumption that board specific platform code will be used to manage chip selects. Individual drivers can define additional properties to support describing the chip select layout. -Optional properties: +Optional properties (master mode only): - cs-gpios - gpios chip select. - num-cs - total number of chipselects. @@ -41,28 +47,36 @@ cs1 : native cs2 : &gpio1 1 0 cs3 : &gpio1 2 0 -SPI slave nodes must be children of the SPI master node and can -contain the following properties. -- reg - (required) chip select address of device. -- compatible - (required) name of SPI device following generic names - recommended practice. -- spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz. -- spi-cpol - (optional) Empty property indicating device requires - inverse clock polarity (CPOL) mode. -- spi-cpha - (optional) Empty property indicating device requires - shifted clock phase (CPHA) mode. -- spi-cs-high - (optional) Empty property indicating device requires - chip select active high. -- spi-3wire - (optional) Empty property indicating device requires - 3-wire mode. -- spi-lsb-first - (optional) Empty property indicating device requires - LSB first mode. -- spi-tx-bus-width - (optional) The bus width (number of data wires) that is - used for MOSI. Defaults to 1 if not present. -- spi-rx-bus-width - (optional) The bus width (number of data wires) that is - used for MISO. Defaults to 1 if not present. -- spi-rx-delay-us - (optional) Microsecond delay after a read transfer. -- spi-tx-delay-us - (optional) Microsecond delay after a write transfer. + +SPI slave nodes must be children of the SPI controller node. + +In master mode, one or more slave nodes (up to the number of chip selects) can +be present. Required properties are: +- compatible - Name of SPI device following generic names recommended + practice. +- reg - Chip select address of device. +- spi-max-frequency - Maximum SPI clocking speed of device in Hz. + +In slave mode, the (single) slave node is optional. +If present, it must be called "slave". Required properties are: +- compatible - Name of SPI device following generic names recommended + practice. + +All slave nodes can contain the following optional properties: +- spi-cpol - Empty property indicating device requires inverse clock + polarity (CPOL) mode. +- spi-cpha - Empty property indicating device requires shifted clock + phase (CPHA) mode. +- spi-cs-high - Empty property indicating device requires chip select + active high. +- spi-3wire - Empty property indicating device requires 3-wire mode. +- spi-lsb-first - Empty property indicating device requires LSB first mode. +- spi-tx-bus-width - The bus width (number of data wires) that is used for MOSI. + Defaults to 1 if not present. +- spi-rx-bus-width - The bus width (number of data wires) that is used for MISO. + Defaults to 1 if not present. +- spi-rx-delay-us - Microsecond delay after a read transfer. +- spi-tx-delay-us - Microsecond delay after a write transfer. Some SPI controllers and devices support Dual and Quad SPI transfer mode. It allows data in the SPI system to be transferred using 2 wires (DUAL) or 4
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- v3: - In SPI slave mode, represent the (single) slave device again as a child of the controller node, which is now optional, and must be named "slave" if present, - Split slave node properties in master mode, slave mode, and common properties, v2: - Do not create a child node in SPI slave mode. Instead, add an "spi-slave" property, and put the mode properties in the controller node. --- Documentation/devicetree/bindings/spi/spi-bus.txt | 76 ++++++++++++++--------- 1 file changed, 45 insertions(+), 31 deletions(-)