Re: [RFC] Add Input IOCTL for accelerometer devices

[Trilok Soni]

Hi Felipe,

Adding linux-input and Jonathan, so not deleting any lines from this e-mail.

On Fri, May 15, 2009 at 6:46 PM, Felipe Balbi <felipe.balbi@xxxxxxxxx> wrote:
> Hi all,
>
> the following patch is just an idea to see how the community feels about
> it. Considering accelerometer devices, you might have different use
> cases for it while running different applications. You could be using it
> for screen rotation in one case but when opening a game, you could use
> it as a game controller by turning the device side-by-side.

There was one proposal from Jonathan called Industrial IO patchset
which tried to address these sensor devices. Please grep in your
linux-kernel archieve. I believe there are accelerometer drivers under
drivers/hwmon.

>
> Thinking about that, I decided it would be nice to have some parameters
> configured at runtime in order to be able to use the accelerometer on
> different use cases.
>
> The following proposal (really draft) tries to add a new IOCTL on input
> layer such as userland could use that for passing proper parameters to
> accelerometer drivers.
>
> ps: the patch is in really early stage, I'm guessing the best would be
> to, as force feedback devices, provide proper registration for an
> accelerometer device.
>
> diff --git a/include/linux/input.h b/include/linux/input.h
> index adc1332..c3c9e82 100644
> --- a/include/linux/input.h
> +++ b/include/linux/input.h
> @@ -55,6 +55,26 @@ struct input_absinfo {
>        __s32 flat;
>  };
>
> +#define INPUT_ACCEL_IRQ_NONE   0
> +#define INPUT_ACCEL_IRQ_HIGH   BIT(0)
> +#define INPUT_ACCEL_IRQ_LOW    BIT(1)
> +#define INPUT_ACCEL_IRQ_LATCH  BIT(2)
> +
> +struct input_accelinfo {
> +       __u32 threshold;
> +       __u32 duration;
> +
> +       /* the following 4 fields configure how the irqs will be generated:
> +        * - High Event
> +        * - Low Event
> +        * - Latch irq request
> +        */
> +       __u8 x_irq;
> +       __u8 y_irq;
> +       __u8 z_irq;
> +       __u8 click_irq;
> +};
> +
>  #define EVIOCGVERSION          _IOR('E', 0x01, int)                    /* get driver version */
>  #define EVIOCGID               _IOR('E', 0x02, struct input_id)        /* get device ID */
>  #define EVIOCGREP              _IOR('E', 0x03, int[2])                 /* get repeat settings */
> @@ -81,6 +101,8 @@ struct input_absinfo {
>
>  #define EVIOCGRAB              _IOW('E', 0x90, int)                    /* Grab/Release device */
>
> +#define EVIOCACCELINFO         _IOW('E', 0x91, struct input_accelinfo) /* set accelerometer's parameters */
> +
>  /*
>  * Event types
>  */
> @@ -975,6 +997,8 @@ struct ff_effect {
>  #include <linux/timer.h>
>  #include <linux/mod_devicetable.h>
>
> +struct input_accelinfo;
> +
>  /**
>  * struct input_dev - represents an input device
>  * @name: name of the device
> @@ -1069,6 +1093,7 @@ struct input_dev {
>        void *keycode;
>        int (*setkeycode)(struct input_dev *dev, int scancode, int keycode);
>        int (*getkeycode)(struct input_dev *dev, int scancode, int *keycode);
> +       int (*set_accelinfo)(struct input_dev *dev, struct input_accelinfo *info);
>
>        struct ff_device *ff;
>
>
>
> --
> balbi
> --
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---Trilok Soni
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