Re: [PATCH v4] extcon: gpio: Add the support for Device tree bindings

[Laxman Dewangan <ldewangan@nvidia.com>]

Hi Rob,

On Tuesday 31 May 2016 07:05 PM, Rob Herring wrote:
> On Tue, May 31, 2016 at 2:35 AM, Chanwoo Choi <cw00.choi@samsung.com> wrote:
>> The extcon-gpio.c driver can separate the kind of external connector
>> by using the 'extcon-id' property.
> This use of DT is just broken. Come up with another way.
>
>


Can we have the DT binding very similar to IIO, clock, reset etc?

Here is details for extcon-jack DT binding and its client:

The client can get the cable information through its node or extcon name
and once cable information is available, it can register for 
notification when state gets changed.

The typical dt nodes are:

     Extcon-driver node:

         extcon: arizona-extcon {
                 compatible = "wlf,arizona-extcon";
                 #extcon-cells = <1>;
         };



     Driver need to specify the cable ID as
      Cable                      ID
      ----------------------------
       Mechanical                0
       Microphone               1
       Headphone               2
       Line-out                    3

     Here #extcon-cells is must and specifies the size of extcon cells. 
The client need to provide the driver specific information as argument 
along with handle.


Extcon Client node:

         audio-controller@b0000 {
                ::::
                 extcon-cables = <&extcon 1>, <&extcon 3>;
                 extcon-cable-names = "Microphone", "Line-out";
         };

and client driver can register the cable by passing the cable name
as above along with its node.

struct extcon_cable {
     struct extcon_dev *edev,
     int cable_id;
};

edev_mic_cable = extcon_get_extcon_cable(dev, "Microphone");
extcon_register_notification(edev_mic_cable, notifier);

edev_line_out_cable = extcon_get_extcon_cable(dev, "Line-out");
extcon_register_notification(edev_line_out_cable, notifier);


Prototype:
struct extcon_cable *extcon_get_extcon_cable(struct device *dev, const 
char *cable_name)