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Commit 5866d9e3 authored by Jason Gerecke's avatar Jason Gerecke Committed by Dmitry Torokhov
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Input: wacom - use full 32-bit HID Usage value in switch statement 



A HID Usage is a 32-bit value: an upper 16-bit "page" and a lower 16-bit
ID. While the two halves are normally reported seperately, only the
combination uniquely idenfifes a particular HID Usage.

The existing code performs the comparison in two steps, first performing a
switch on the ID and then verifying the page within each case. While this
works fine, it is very akward to handle two Usages that share a single ID,
such as HID_USAGE_PRESSURE and HID_USAGE_X because the case statement can
only have a single identifier.

To work around this, we now check the full 32-bit HID Usage directly rather
than first checking the ID and then the page.  This allows the switch
statement to have distinct cases for e.g. HID_USAGE_PRESSURE and
HID_USAGE_X.

Signed-off-by: default avatarJason Gerecke <killertofu@gmail.com>
Tested-by: default avatarAaron Skomra <Aaron.Skomra@wacom.com>
Reviewed-by: default avatarCarl Worth <cworth@cworth.org>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 91ae0e77

drivers/input/tablet/wacom_sys.c

+109 −128
Original line number Diff line number Diff line
@@ -22,23 +22,17 @@ 
#define HID_USAGE_PAGE_DIGITIZER	0x0d

#define HID_USAGE_PAGE_DESKTOP		0x01

#define HID_USAGE			0x09

#define HID_USAGE_X			0x30

#define HID_USAGE_Y			0x31

#define HID_USAGE_X_TILT		0x3d

#define HID_USAGE_Y_TILT		0x3e

#define HID_USAGE_FINGER		0x22

#define HID_USAGE_STYLUS		0x20

#define HID_USAGE_CONTACTMAX		0x55

#define HID_USAGE_X			((HID_USAGE_PAGE_DESKTOP << 16) | 0x30)

#define HID_USAGE_Y			((HID_USAGE_PAGE_DESKTOP << 16) | 0x31)

#define HID_USAGE_X_TILT		((HID_USAGE_PAGE_DIGITIZER << 16) | 0x3d)

#define HID_USAGE_Y_TILT		((HID_USAGE_PAGE_DIGITIZER << 16) | 0x3e)

#define HID_USAGE_FINGER		((HID_USAGE_PAGE_DIGITIZER << 16) | 0x22)

#define HID_USAGE_STYLUS		((HID_USAGE_PAGE_DIGITIZER << 16) | 0x20)

#define HID_USAGE_CONTACTMAX		((HID_USAGE_PAGE_DIGITIZER << 16) | 0x55)

#define HID_COLLECTION			0xa1

#define HID_COLLECTION_LOGICAL		0x02

#define HID_COLLECTION_END		0xc0



enum {

	WCM_UNDEFINED = 0,

	WCM_DESKTOP,

	WCM_DIGITIZER,

};



struct hid_descriptor {

	struct usb_descriptor_header header;

	__le16   bcdHID;
@@ -305,7 +299,7 @@ static int wacom_parse_hid(struct usb_interface *intf, 
	char limit = 0;

	/* result has to be defined as int for some devices */

	int result = 0, touch_max = 0;

	int i = 0, usage = WCM_UNDEFINED, finger = 0, pen = 0;

	int i = 0, page = 0, finger = 0, pen = 0;

	unsigned char *report;



	report = kzalloc(hid_desc->wDescriptorLength, GFP_KERNEL);
@@ -332,23 +326,13 @@ static int wacom_parse_hid(struct usb_interface *intf, 


		switch (report[i]) {

		case HID_USAGE_PAGE:

			switch (report[i + 1]) {

			case HID_USAGE_PAGE_DIGITIZER:

				usage = WCM_DIGITIZER;

			page = report[i + 1];

			i++;

			break;



			case HID_USAGE_PAGE_DESKTOP:

				usage = WCM_DESKTOP;

				i++;

				break;

			}

			break;



		case HID_USAGE:

			switch (report[i + 1]) {

			switch (page << 16 | report[i + 1]) {

			case HID_USAGE_X:

				if (usage == WCM_DESKTOP) {

				if (finger) {

					features->device_type = BTN_TOOL_FINGER;

					/* touch device at least supports one touch point */
@@ -414,11 +398,9 @@ static int wacom_parse_hid(struct usb_interface *intf, 
						get_unaligned_le16(&report[i + 3]);

					i += 4;

				}

				}

				break;



			case HID_USAGE_Y:

				if (usage == WCM_DESKTOP) {

				if (finger) {

					switch (features->type) {

					case TABLETPC2FG:
@@ -460,7 +442,6 @@ static int wacom_parse_hid(struct usb_interface *intf, 
						get_unaligned_le16(&report[i + 3]);

					i += 4;

				}

				}

				break;



			case HID_USAGE_FINGER:
@@ -489,7 +470,7 @@ static int wacom_parse_hid(struct usb_interface *intf, 


		case HID_COLLECTION_END:

			/* reset UsagePage and Finger */

			finger = usage = 0;

			finger = page = 0;

			break;



		case HID_COLLECTION: