On 10/11/2011 11:06 AM, Thomas Abraham wrote: > On 11 October 2011 21:00, Rob Herring <robherring2@xxxxxxxxx> wrote: >> On 10/11/2011 10:19 AM, Thomas Abraham wrote: >>> Hi Rob, >>> >>> On 11 October 2011 20:41, Rob Herring <robherring2@xxxxxxxxx> wrote: >>>> Thomas, >>>> >>>> On 10/11/2011 03:16 AM, Thomas Abraham wrote: >>>>> As gpio chips get registered, a device tree node which represents the >>>>> gpio chip is searched and attached to it. A translate function is also >>>>> provided to convert the gpio specifier into actual platform settings >>>>> for pin function selection, pull up/down and driver strength settings. >>>>> >>>>> Signed-off-by: Thomas Abraham <thomas.abraham@xxxxxxxxxx> >>>>> --- >>>>> This patch is based on the latest consolidated Samsung GPIO driver available >>>>> in the following tree: >>>>> https://github.com/kgene/linux-samsung.git branch: for-next >>>>> >>>>> .../devicetree/bindings/gpio/gpio-samsung.txt | 30 +++++++++++ >>>>> drivers/gpio/gpio-samsung.c | 53 ++++++++++++++++++++ >>>>> 2 files changed, 83 insertions(+), 0 deletions(-) >>>>> create mode 100644 Documentation/devicetree/bindings/gpio/gpio-samsung.txt >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/gpio/gpio-samsung.txt b/Documentation/devicetree/bindings/gpio/gpio-samsung.txt >>>>> new file mode 100644 >>>>> index 0000000..883faeb >>>>> --- /dev/null >>>>> +++ b/Documentation/devicetree/bindings/gpio/gpio-samsung.txt >>>>> @@ -0,0 +1,30 @@ >>>>> +Samsung Exynos4 GPIO Controller >>>>> + >>>>> +Required properties: >>>>> +- compatible: Format of compatible property value should be >>>>> + "samsung,exynos4-gpio-<controller_name>". Example: For GPA0 controller, the >>>>> + compatible property value should be "samsung,exynos4-gpio-gpa0". >>>> >>>> Isn't gpa0 an instance of the h/w, not a version? >>> >>> GPA0 is a instance of the gpio controller. There are several such >>> instances and there could be differences in those instances such as >>> the number of GPIO lines managed by that gpio controller instance. >>> >> >> That doesn't seem like a reason to have different compatible strings. >> Does that affect the programming model of the controller? Unused lines >> whether at the board level or SOC level shouldn't really matter. > > > No, that does not affect the programming of the controller. The reason > for the instance name extension in compatible string is to match the > gpio_chip with a gpio controller node. When matched, the of_node > pointer of the gpio_chip is set to point to that controller node. > > This might not be the best possible implementation but the device tree > support code in this patch is dictated by the structure of the > existing gpio driver code. As you suggested previously, I will look at > reworking the gpio driver a little later but for now, there was a need > for working gpio dt solution to make progress on dt support for other > controllers. Linux should provide clues about what's needed in a binding, but the binding should not be defined based on current Linux code. Doing the binding one way and changing it later is not a good plan. I think you need to convert all users of gpio over as well so you can move to dynamic gpio_chip creation and gpio numbering. Or maybe you can match based on base address? This is going to be a common problem as gpio is converted over to DT. Perhaps Grant or others have suggestions on the approach to use. Rob -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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