Hi!

Take a *long* look at vojtech's generic input drivers. He _already_
does touch screens, and seems to superior to what is in linus' tree.

> 	As this was sent to the generic 'handhelds' rather than the
> 	specific 'handhelds-linux' lists, I though it might be of some
> 	interest - maybe even towards trying to have a similar interface
> 	for NetBSD...
> 
> 		David/absolute
> 				       -- www.netbsd.org: No hype required --
> 
> ---------- Forwarded message ----------
> Date: Mon, 10 Jul 2000 22:43:55 +1000
> From: Charlie Flynn <flynn@ozy.dec.com>
> Reply-To: handhelds@handhelds.org
> To: linux-arm@vger.rutgers.edu, handhelds@handhelds.org
> Subject: [Handhelds] Re: Touch Screen Driver Generic Interface for all
>     Linux SA11x0 platforms.
> 
> Hi,
> 
> I attach my first cut of a generic touch screen driver specification as promised
> from my earlier email.
> This specification is based around my experience with the Compaq iPAQ H3600 touch
> screen driver, however I have tried to make it as generic as possible for all
> Linux platforms.
> 
> If nothing else I hope it will at least start the ball rolling in the quest to
> gain consensus on what a generic touch screen driver will eventually look like.
> 
> I will also put this spec in html format on the www.handhelds.org web site.
> 
> Since there has also been some interest in the handhelds@handhelds.org mailing
> list I will post it in both lists for now with a view to maybe moving the
> discussion to one (which one?) of the lists.
> 
> Regards
> --Charlie
> 
> +++++++++++++++++++++++++++
> 
> MAJOR NUMBER
> --------------------
> (TBD)
> A generic Touch Screen major number to be registered according to the procedure
> documented in../linux/Documentation/devices.txt.
> A major number 10 seems the most likely candidate.
> 
> DEVICE NODES and MINOR NUMBERS
> ----------------------------------------------
> 
> /dev/ts    - This is the device used to read calibrated touch screen events
> 
> A generic Touch Screen device name (/dev/ts)  and minor number (TBD) to be
> registered according to the procedure documented in
> ../linux/Documentation/devices.txt.
> 
> TOUCH SCREEN EVENT STRUCTURE (TS_EVENT)
> -----------------------------------------------------------
> 
> This is the structure contains the X and Y pixel coordinates of a single touch
> screen event. It is passed from the driver to the user by the read() function.
> 
> typedef struct {
>     short pressure;    /* used to determine if the touch screen pen is UP or
> DOWN  (Note 1) */
>     short x;                /* If  pen is DOWN then this is the pixel X
> coordinate */
>     short y;                /* If  pen is DOWN then this is the pixel Y
> coordinate  */
>     /* any more ? */
> } TS_EVENT;
> 
> 
> USER LEVEL FILE OPERATIONS
> --------------------------------------
> In addition to open(), close() and ioctl() functions, blocking and non-blocking
> reads and asynchronous notification (SIGIO) should be supported at the user
> level. The select/poll mechanism will be used for non-blocking reads.
> See the EXAMPLES section for pointers to example code on the above functions.
> 
> KERNEL LEVEL FILE OPERATIONS
> ------------------------------------------
> 
> The following file operations pertain to device /dev/ts.
> 
> _read()
> Blocking reads will block until a complete TS_EVENT structure (see below) can be
> returned.
> 
> _fasync()
> Will send a SIGIO to user when there is an event to report. An event is defined
> as reception of a complete TS_EVENT structure.
> 
> _poll()
> If there are 1 or more TS_EVENT structures to be read from the driver, then this
> function will return the (POLLIN | POLLRDNORM) flags otherwise a zero will be
> returned.
> 
> _ioctl()
> The list of ioctls will depend on the hardware used to implement the touch screen
> (example UCB1200).
> Initialisation ioctls will be called by the driver’s init_module() or equivalent.
> 
> The calibration application (if adopted in user space) will have it’s own ioctls
> (see CALIBRATION section).
> 
> The ioctl command numbers should be ‘mangled’ using the _IO,_IOW,_IOR,_IOWR
> macros as defined in  <linux/ioctl.h>
> A ‘magic number’ of ‘?’ should be used (see CALIBRATION section)
> 
> TOUCH SCREEN EXAMPLE  CODE
> ------------------------------------------
> 
> The following example code can be found in the ../apps/h3600_test directory in
> the handhelds.org CVS tree.
> 
> ts_poll.c  - example of a non-blocking read using the poll/select mechanism.
> ts_read.c  - example of a blocking read.
> fasynctst.c - example of how asynchronous notifications are handled in user
> space.
> 
> The driver which implements most of this specification  is called h3650_ts.c and
> can be found in the ../drivers/char directory in the handhelds.org CVS tree.
> 
> CALIBRATION
> ------------------
> (This section assumes the calibration mechanism will be an application)
> 
> The (H3600) calibration parameters are calculated by a separate calibration
> application. It uses the Itsy calibration paradigm. The touch screen sensor is
> assumed linear, conforming to the equations of a straight line:
> 
> Xcal = mxXraw + Cx
> Ycal = myYraw + Cy
> 
> Calibration information is held in the TS_CAL structure and is passed to and from
> the driver using the TS_GET_CALIBRATE and TS_SET_CALIBRATE ioctls.
> 
> #define  TS_SET_CALIBRATE _IOW(IOC_MAGIC,2,TS_CAL);
> #define  TS_GET_CALIBRATE _IOW(IOC_MAGIC,3,TS_CAL);
> 
> The TS_CAL structure is used to convert RAW touch screen coordinates (Xraw and
> Yraw) to calibrated touch screen coordinates (Xcal and Ycal).
> 
> typedef struct {
>     int xscale;
>     int xtrans;
>     int yscale;
>     int ytrans;
>     int xyswap;
> } TS_CAL;
> 
> 
> The TS_SET_RAW_ON/OFF ioctl pair will switch between raw and calibrated data. The
> calibration application will instruct the driver to return only RAW events using
> the TS_SET_RAW_ON ioctl and when calibrated the calibration application will
> switch the driver back to returning calibrated events using the TS_SET_RAW_OFF
> (Note 2)
> 
> #define  TS_SET_RAW_ON  _IO(IOC_MAGIC,0);
> #define  TS_SET_RAW_OFF  _IO(IOC_MAGIC,1);
> 
> TOUCH SCREEN CALIBRATION APPLICATION EXAMPLE  CODE
> -----------------------------------------------------------------------------
> 
> The H3600 calibration application can be found in ../apps/ts_calibrate.c in the
> handhelds.org CVS tree. This code is extensively commented and will explain how
> the Itsy calibration application works. Note is uses a device called
> /dev/h3600_tsraw to get raw data. This device may be superceded by the
> TS_SET_RAW_ON/OFF ioctls.
> 
> Notes
> 1. Some systems return pressure as a value between 0 and xxxx which is used to
> determine the pen status (UP or DOWN). The Compaq iPAQ H3600 just returns
> pressure=0 (UP) or pressure=1 (DOWN). If UP then X and Y coordinates are set to
> –1. Should this member variable be called something else?
> 2. The Compaq H3600 driver does not use this mechanism at present.
> 
> +++++++++++++++++++++++++++
> 
> Charlie Flynn wrote:
> 
> > Hello,
> >
> > My name is Charlie Flynn and I have just completed V1.0 of a  touch
> > screen driver  for the Compaq iPAQ H3600 running Linux 2.4.0-test1.
> >
> > I was thinking it would be a good idea if we had a generic interface to
> > the touch screen drivers of all Linux SA11x0  platforms.
> >
> > This would allow clients ( such as the X windows device dependent layer
> > ) to work, without modification, with all Linux SA11x0 touch screen
> > drivers.
> >
> > I know it's a bit late to ask this ;-) but is there already a document
> > describing a generic TSD interface for these platforms?
> >
> > Assuming there isn't such a document and also assuming people think it's
> > worth pursuing I can start the ball rolling by posting a draft spec to
> > the linux-arm-kernel mailing list which I assume would be the most
> > appropriate place to discuss this issue.
> >
> > Regards
> > --Charlie
> >
> > unsubscribe: body of `unsubscribe linux-arm' to majordomo@vger.rutgers.edu
> > ++        Please use linux-arm-kernel@lists.arm.linux.org.uk for           ++
> > ++                        kernel-related discussions.                      ++
> 
> _______________________________________________
> Handhelds mailing list
> Handhelds@handhelds.org
> http://handhelds.org/mailman/listinfo/handhelds

-- 
The best software in life is free (not shareware)!		Pavel
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