On Fri, Oct 24, 2008 at 3:10 PM, Anton Vorontsov
<[EMAIL PROTECTED]> wrote:
> On Fri, Oct 24, 2008 at 10:08:59PM +0200, Wolfgang Ocker wrote:
>> SPI slave devices require the specification of a chip select address.
>> This patch allows that specification using the gpios property. The reg
>> property remains supported.
>>
>> Signed-off-by: Wolfgang Ocker <[EMAIL PROTECTED]>
>> ---
>>
>> --- linux-2.6.27.3/drivers/of/of_spi.c.of_spi_gpio 2008-10-22
>> 23:38:01.000000000 +0200
>> +++ linux-2.6.27.3/drivers/of/of_spi.c.of_spi_cshigh 2008-10-24
>> 21:36:39.000000000 +0200
> [...]
>> --- linux-2.6.27.3/Documentation/powerpc/booting-without-of.txt.of_spi_gpio
>> 2008-10-22 23:38:01.000000000 +0200
>> +++
>> linux-2.6.27.3/Documentation/powerpc/booting-without-of.txt.of_spi_cshigh
>> 2008-10-24 21:57:16.000000000 +0200
>> @@ -1936,7 +1938,7 @@ platforms are moved over to use the flat
>> [EMAIL PROTECTED] {
>> compatible = "ti,tlv320aic26";
>> spi-max-frequency = <100000>;
>> - reg = <1>;
>> + gpios = <&GPIO1 3>;
>> };
>> };
>
> Close, but no cigar. Sorry. ;-) The bindings are fine as is, you don't
> need to change them.
>
> The scheme should look like this:
>
> spi-controller {
> #address-cells = <1>;
> #size-cells = <0>;
>
> /* two GPIOs, representing two chip selects: 0 and 1 */
> gpios = <&pio 5 0 &pio 16 0>;
>
> [EMAIL PROTECTED] {
> reg = <0>;
> };
>
> [EMAIL PROTECTED] {
> reg = <1>;
> };
> }
>
> Notice that "gpios" is spi-controller's property, not spi devices'.
> It is truly as hardware works, SPI controllers consists of two units:
> I/O, and chip-select machine. Most spi controllers don't have
> dedicated chip-select machines, so they use GPIOs.
FWIW, I 100% agree.
g.
--
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
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