[PATCH 3/4] spi: Add OF binding support for SPI busses
grant.likely at secretlab.ca
Sat May 17 06:51:45 EST 2008
On Fri, May 16, 2008 at 2:47 PM, Randy Dunlap <randy.dunlap at oracle.com> wrote:
> On Fri, 16 May 2008 13:36:13 -0600 Grant Likely wrote:
>> diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt
>> index 1d2a772..452c242 100644
>> --- a/Documentation/powerpc/booting-without-of.txt
>> +++ b/Documentation/powerpc/booting-without-of.txt
>> @@ -2870,6 +2871,66 @@ platforms are moved over to use the flattened-device-tree model.
>> reg = <0xe8000000 32>;
>> + s) 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.
>> + The SPI master node requires the following 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.
>> + 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
>> + assigning chip select numbers. Since SPI chip select configuration is
>> + flexible and non-standardized, it is left out of this binding with the
>> + 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.
>> + 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
>> + - max-speed - (optional) Maximum SPI clocking speed of device in Hz
>> + - spi,cpol - (optional) Device requires inverse clock polarity
>> + - spi,cpha - (optional) Device requires shifted clock phase
>> + - linux,modalias - (optional, Linux specific) Force binding of SPI device
>> + to a particular spi_device driver. Useful for changing
>> + driver binding between spidev and a kernel spi driver.
> You mostly capitalize "SPI" in sentences (i.e., when it's not part of
> a function name or OF data), so could the 3 underlined instances of it
> also be all caps?
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
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