Re: [PATCH 3/4] spi: Add OF binding support for SPI busses
From: Randy Dunlap <hidden>
Date: 2008-05-16 20:49:06
Also in:
linux-spi, lkml
On Fri, 16 May 2008 13:36:13 -0600 Grant Likely wrote:
quoted hunk ↗ jump to hunk
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
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+ 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
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+ 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.
~~~ Hi, 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? Thanks, --- ~Randy