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    SubjectRE: [PATCH v2 3/5] of-bindings: Add binding documentation for SPI bussesand devices
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    From


    > -----Original Message-----
    > From: linuxppc-dev-bounces+b11801=freescale.com@ozlabs.org
    > [mailto:linuxppc-dev-bounces+b11801=freescale.com@ozlabs.org]
    > On Behalf Of Grant Likely
    > Sent: 2008?7?3? 9:03
    > To: linuxppc-dev@ozlabs.org;
    > spi-devel-general@lists.sourceforge.net; linux-kernel@vger.kernel.org
    > Cc: david-b@pacbell.net; fabrizio.garetto@gmail.com
    > Subject: [PATCH v2 3/5] of-bindings: Add binding
    > documentation for SPI bussesand devices
    >
    > From: Grant Likely <grant.likely@secretlab.ca>
    >
    > Add documentation about how to describe SPI busses in the device tree.
    >
    > Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
    > ---
    >
    > Documentation/powerpc/booting-without-of.txt | 60
    > ++++++++++++++++++++++++++
    > 1 files changed, 60 insertions(+), 0 deletions(-)
    >
    > diff --git a/Documentation/powerpc/booting-without-of.txt
    > b/Documentation/powerpc/booting-without-of.txt
    > index 1d2a772..7d3564f 100644
    > --- a/Documentation/powerpc/booting-without-of.txt
    > +++ b/Documentation/powerpc/booting-without-of.txt
    > @@ -58,6 +58,7 @@ Table of Contents
    > o) Xilinx IP cores
    > p) Freescale Synchronous Serial Interface
    > q) USB EHCI controllers
    > + t) SPI busses
    >
    > VII - Marvell Discovery mv64[345]6x System Controller chips
    > 1) The /system-controller node
    > @@ -2870,6 +2871,65 @@ platforms are moved over to use the
    > flattened-device-tree model.
    > reg = <0xe8000000 32>;
    > };
    >
    > + t) 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 - (required) 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.
    > +

    How about adding a "model" property to describe actual devie type.
    Such as using a "sst25vf040b" device with spi-interface, we can
    use model="sst25vf040b" to describe it.


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