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

[Chen Gong]

> -----Original Message-----
> From: linuxppc-dev-bounces+b11801=freescale.com@xxxxxxxxxx 
> [mailto:linuxppc-dev-bounces+b11801=freescale.com@xxxxxxxxxx] 
> On Behalf Of Grant Likely
> Sent: 2008?7?3? 9:03
> To: linuxppc-dev@xxxxxxxxxx; 
> spi-devel-general@xxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: david-b@xxxxxxxxxxx; fabrizio.garetto@xxxxxxxxx
> Subject: [PATCH v2 3/5] of-bindings: Add binding 
> documentation for SPI bussesand devices
> 
> From: Grant Likely <grant.likely@xxxxxxxxxxxx>
> 
> Add documentation about how to describe SPI busses in the device tree.
> 
> Signed-off-by: Grant Likely <grant.likely@xxxxxxxxxxxx>
> ---
> 
>  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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