On 17 November 2011 13:38, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
>> Linus,
>> Is there a plan to move even the data that exists in the pinmux
>> drivers today (including the function/pin-groups definition)
>> eventually to DT? Or is it just the 'mapping' data to map
>> devices to functions (that today is done from board files) which
>> alone will be moved?
>
> Not for the U300 driver, for the simple reason that it cannot
> use device tree. So both methods of providing the data need
> to be allowed - either as static data (the U300 driver does not
> even have platform data, the pin data is encoded in the driver
> itself since it's tied to U300 and not used for any other systems
> or variants) or as device tree lookups.
>
> That said I have no clue on how to make the DT bindings
> FTM, patches and suggestions welcome.
For now, the Samsung GPIO, Pinconfig and Pinmux information is
represented in device tree as listed below.
i2c@1C004000 {
compatible = "...";
reg = <0x... 0x..>;
gpios = <&gpa0 2 2 3 0>,
<&gpa0 3 2 3 0>;
...
};
The format of the gpio specifier is
<[Pad Controller phandle] [pin number within the controller] [Pin Mux
Function] [Pull Up/Down] [Drive Strength]>
>From a perspective of writing a 'gpios' property for a device node,
this is quite simple. Looking up the hardware manual of the SoC can
provide all the values that should be used in the gpio specifier.
The GPIO/PinCtrl driver can provide a translate function that picks up
the values for the gpio specifier and writes the same value to the
pad-controller registers. But, this a deviation from the existing
pinctrl subsystem code which mainly relies on name of the pin-group
and pin-function.
Does this seem to be a feasible option for specifying
gpio/pinconfig/pinmux dt bindings?
Thanks.
Thomas.
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