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    SubjectRe: [RFC][PATCH] input: Introduce device information ioctl
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    On Mon, Dec 6, 2010 at 11:25 PM, Henrik Rydberg <rydberg@euromail.se> wrote:
    > Today, userspace sets up an input device based on the data it emits.
    > This is not always enough; a tablet and a touchscreen may emit exactly
    > the same data, for instance, but the former should be set up with a
    > pointer whereas the latter does not need to. Recently, a new type of
    > touchpad has emerged where the buttons are under the pad, which changes
    > handling logic without changing the emitted data. This patch introduces
    > a new ioctl, EVIOCGDEVINFO, which allows userspace to extract information
    > about the device resulting in proper setup.
    >
    > Suggested-by: Dmitry Torokhov <dtor@mail.ru>
    > Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
    > Cc: Ping Cheng <pingc@wacom.com>
    > Cc: Chris Bagwell <chris@cnpbagwell.com>
    > ---
    > Hi all,
    >
    > Here is a patch attempting to formulate Dmitry's device type idea. It
    > compiles, but further testing awaits a general consesus on the device
    > types and capabilities to start out with. Are the ones listed here apt
    > for the job?
    >
    > Cheers,
    > Henrik
    >
    >  drivers/input/evdev.c |    6 ++++++
    >  include/linux/input.h |   34 ++++++++++++++++++++++++++++++++++
    >  2 files changed, 40 insertions(+), 0 deletions(-)
    >
    > diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
    > index e3f7fc6..db78592 100644
    > --- a/drivers/input/evdev.c
    > +++ b/drivers/input/evdev.c
    > @@ -632,6 +632,12 @@ static long evdev_do_ioctl(struct file *file, unsigned int cmd,
    >                        return -EFAULT;
    >                return 0;
    >
    > +       case EVIOCGDEVINFO:
    > +               if (copy_to_user(p, &dev->devinfo,
    > +                                sizeof(struct input_devinfo)))
    > +                       return -EFAULT;
    > +               return 0;
    > +
    >        case EVIOCGREP:
    >                if (!test_bit(EV_REP, dev->evbit))
    >                        return -ENOSYS;
    > diff --git a/include/linux/input.h b/include/linux/input.h
    > index 6ef4446..8c58d2a 100644
    > --- a/include/linux/input.h
    > +++ b/include/linux/input.h
    > @@ -57,6 +57,21 @@ struct input_absinfo {
    >  };
    >
    >  /**
    > + * struct input_devinfo - device information via EVIOCGDEVINFO ioctl
    > + * @types: bitmask of types (DEVTYPE_*) matching this device
    > + * @capabilities: bitmask of capabilities (DEVCAPS_*) of this device
    > + *
    > + * This struct provides information about the device needed for
    > + * automatic setup in userspace, such as if the device is direct
    > + * (touchscreen) or indirect (touchpad), and if there are other
    > + * special considerations, such as the touchpad also being a button.

    I guess you are talking about the pad is also a button. What about the
    pad has buttons? And there could be more than one button on it. Can we
    pass the number of buttons on the pad as well?

    > + */
    > +struct input_devinfo {
    > +       __u32 types;
    > +       __u32 capabilities;
    > +};
    > +
    > +/**
    >  * struct input_keymap_entry - used by EVIOCGKEYCODE/EVIOCSKEYCODE ioctls
    >  * @scancode: scancode represented in machine-endian form.
    >  * @len: length of the scancode that resides in @scancode buffer.
    > @@ -91,6 +106,7 @@ struct input_keymap_entry {
    >  #define EVIOCGNAME(len)                _IOC(_IOC_READ, 'E', 0x06, len)         /* get device name */
    >  #define EVIOCGPHYS(len)                _IOC(_IOC_READ, 'E', 0x07, len)         /* get physical location */
    >  #define EVIOCGUNIQ(len)                _IOC(_IOC_READ, 'E', 0x08, len)         /* get unique identifier */
    > +#define EVIOCGDEVINFO          _IOR('E', 0x09, struct input_devinfo)   /* get device information */
    >
    >  #define EVIOCGKEY(len)         _IOC(_IOC_READ, 'E', 0x18, len)         /* get global key state */
    >  #define EVIOCGLED(len)         _IOC(_IOC_READ, 'E', 0x19, len)         /* get all LEDs */
    > @@ -108,6 +124,23 @@ struct input_keymap_entry {
    >  #define EVIOCGRAB              _IOW('E', 0x90, int)                    /* Grab/Release device */
    >
    >  /*
    > + * Device types
    > + */
    > +
    > +#define DEVTYPE_KEYBOARD       0
    > +#define DEVTYPE_MOUSE          1
    > +#define DEVTYPE_JOYSTICK       2
    > +#define DEVTYPE_TOUCHPAD       3
    > +#define DEVTYPE_TABLET         4
    > +#define DEVTYPE_TOUCHSCREEN    5

    TOUCHSCREEN can be finger touch screen and pen touch screen. They are
    different types for clients. Should we add one for pen touch screen,
    something like DEVTYPE_TABLETPC?

    > +
    > +/*
    > + * Device capabilities
    > + */
    > +
    > +#define DEVCAPS_PAD_IS_BUTTON  1

    Do we need the following:

    +#define DEVCAPS_PAD_HAS_BUTTONS 2
    +#define DEVCAPS_PAD_HAS_RINGS 3
    +#define DEVCAPS_PAD_HAS_REL_WHEELS 4
    +#define DEVCAPS_PAD_HAS_ABS_WHEELS 5
    +#define DEVCAPS_PAD_HAS_STRIPS 6

    Thank you.

    Ping

    > +
    > +/*
    >  * Event types
    >  */
    >
    > @@ -1177,6 +1210,7 @@ struct input_dev {
    >        const char *phys;
    >        const char *uniq;
    >        struct input_id id;
    > +       struct input_devinfo devinfo;
    >
    >        unsigned long evbit[BITS_TO_LONGS(EV_CNT)];
    >        unsigned long keybit[BITS_TO_LONGS(KEY_CNT)];
    > --
    > 1.7.1
    >
    > --
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