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Message-ID: <58A20A281BAF1047B4EAE68DE5C0BDC2010121B9@zch01exm21.fsl.freescale.net>
Date: Fri, 4 Jul 2008 11:59:07 +0800
From: "Chen Gong" <G.Chen@...escale.com>
To: "Grant Likely" <grant.likely@...retlab.ca>,
<linuxppc-dev@...abs.org>,
<spi-devel-general@...ts.sourceforge.net>,
<linux-kernel@...r.kernel.org>
Cc: <david-b@...bell.net>, <fabrizio.garetto@...il.com>
Subject: RE: [PATCH v2 3/5] of-bindings: Add binding documentation for SPI bussesand devices
> -----Original Message-----
> From: linuxppc-dev-bounces+b11801=freescale.com@...abs.org
> [mailto:linuxppc-dev-bounces+b11801=freescale.com@...abs.org]
> On Behalf Of Grant Likely
> Sent: 2008?7?3? 9:03
> To: linuxppc-dev@...abs.org;
> spi-devel-general@...ts.sourceforge.net; linux-kernel@...r.kernel.org
> Cc: david-b@...bell.net; fabrizio.garetto@...il.com
> Subject: [PATCH v2 3/5] of-bindings: Add binding
> documentation for SPI bussesand devices
>
> From: Grant Likely <grant.likely@...retlab.ca>
>
> Add documentation about how to describe SPI busses in the device tree.
>
> Signed-off-by: Grant Likely <grant.likely@...retlab.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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