[media] v4l2-core: Add support for touch devices

Some touch controllers send out touch data in a similar way to a
greyscale frame grabber.

Add new device type VFL_TYPE_TOUCH:
- This uses a new device prefix v4l-touch for these devices, to stop
  generic capture software from treating them as webcams. Otherwise,
  touch is treated similarly to video capture.
- Add V4L2_INPUT_TYPE_TOUCH
- Add MEDIA_INTF_T_V4L_TOUCH
- Add V4L2_CAP_TOUCH to indicate device is a touch device

Add formats:
- V4L2_TCH_FMT_DELTA_TD16 for signed 16-bit touch deltas
- V4L2_TCH_FMT_DELTA_TD08 for signed 16-bit touch deltas
- V4L2_TCH_FMT_TU16 for unsigned 16-bit touch data
- V4L2_TCH_FMT_TU08 for unsigned 8-bit touch data

This support will be used by:
- Atmel maXTouch (atmel_mxt_ts)
- Synaptics RMI4.
- sur40

Signed-off-by: Nick Dyer <nick@shmanahar.org>
Tested-by: Chris Healy <cphealy@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

2 files changed, 10 insertions, 0 deletions

diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h
index 7acf0f634f70..4890787731b8 100644
--- a/include/uapi/linux/media.h
+++ b/include/uapi/linux/media.h
@@ -307,6 +307,7 @@ struct media_links_enum {
 #define MEDIA_INTF_T_V4L_RADIO  (MEDIA_INTF_T_V4L_BASE + 2)
 #define MEDIA_INTF_T_V4L_SUBDEV (MEDIA_INTF_T_V4L_BASE + 3)
 #define MEDIA_INTF_T_V4L_SWRADIO (MEDIA_INTF_T_V4L_BASE + 4)
+#define MEDIA_INTF_T_V4L_TOUCH  (MEDIA_INTF_T_V4L_BASE + 5)
 
 #define MEDIA_INTF_T_ALSA_PCM_CAPTURE   (MEDIA_INTF_T_ALSA_BASE)
 #define MEDIA_INTF_T_ALSA_PCM_PLAYBACK  (MEDIA_INTF_T_ALSA_BASE + 1)
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 724f43e69d03..22bad8c741fe 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -440,6 +440,8 @@ struct v4l2_capability {
 #define V4L2_CAP_ASYNCIO                0x02000000  /* async I/O */
 #define V4L2_CAP_STREAMING              0x04000000  /* streaming I/O ioctls */
 
+#define V4L2_CAP_TOUCH                  0x10000000  /* Is a touch device */
+
 #define V4L2_CAP_DEVICE_CAPS            0x80000000  /* sets device capabilities field */
 
 /*
@@ -635,6 +637,12 @@ struct v4l2_pix_format {
 #define V4L2_SDR_FMT_CS14LE       v4l2_fourcc('C', 'S', '1', '4') /* complex s14le */
 #define V4L2_SDR_FMT_RU12LE       v4l2_fourcc('R', 'U', '1', '2') /* real u12le */
 
+/* Touch formats - used for Touch devices */
+#define V4L2_TCH_FMT_DELTA_TD16 v4l2_fourcc('T', 'D', '1', '6') /* 16-bit signed deltas */
+#define V4L2_TCH_FMT_DELTA_TD08 v4l2_fourcc('T', 'D', '0', '8') /* 8-bit signed deltas */
+#define V4L2_TCH_FMT_TU16       v4l2_fourcc('T', 'U', '1', '6') /* 16-bit unsigned touch data */
+#define V4L2_TCH_FMT_TU08       v4l2_fourcc('T', 'U', '0', '8') /* 8-bit unsigned touch data */
+
 /* priv field value to indicates that subsequent fields are valid. */
 #define V4L2_PIX_FMT_PRIV_MAGIC         0xfeedcafe
 
@@ -1401,6 +1409,7 @@ struct v4l2_input {
 /*  Values for the 'type' field */
 #define V4L2_INPUT_TYPE_TUNER           1
 #define V4L2_INPUT_TYPE_CAMERA          2
+#define V4L2_INPUT_TYPE_TOUCH           3
 
 /* field 'status' - general */
 #define V4L2_IN_ST_NO_POWER    0x00000001  /* Attached device is off */