On Mon, Sep 12, 2016 at 10:50:40PM +0200, Geert Uytterhoeven wrote: > Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be> > --- > 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 | 34 > ++++++++++++++--------- > 1 file changed, 21 insertions(+), 13 deletions(-) > > diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt > b/Documentation/devicetree/bindings/spi/spi-bus.txt > index 17822860cb98c34d..1ae28d7cafb68dc5 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.
We'll probably need some way to define what interface/protocol the slave has. Perhaps the most specific compatible should be the protocol the slave uses? Maybe that is how you use a child node? > + > +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. > > @@ -41,12 +47,14 @@ 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. > +In master mode, SPI slave nodes must be children of the SPI controller node. > +In slave mode, the (single) slave device is represented by the controller > node > +itself. SPI slave nodes can contain the following properties. I find this a bit confusing as you talk about master mode, then slave mode, then slave nodes (master mode again). > +- reg - (required, master mode only) 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-max-frequency - (required, master mode only) 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 > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe devicetree" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
