This patch adds support for Philips webcam snapshot button as an
event input device, for consistency with other webcam drivers.
Signed-off-by: Pham Thanh Nam <phamthanhnam.ptn@gmail.com>

diff -uNr a/linux/drivers/media/video/pwc/pwc.h b/linux/drivers/media/video/pwc/pwc.h
--- a/linux/drivers/media/video/pwc/pwc.h	2009-01-03 20:03:43.000000000 +0700
+++ b/linux/drivers/media/video/pwc/pwc.h	2009-01-07 02:10:58.000000000 +0700
@@ -38,6 +38,7 @@
 #include <linux/videodev.h>
 #include <media/v4l2-common.h>
 #include <media/v4l2-ioctl.h>
+#include <linux/input.h>
 
 #include "pwc-uncompress.h"
 #include <media/pwc-ioctl.h>
@@ -256,6 +257,7 @@
    int pan_angle;			/* in degrees * 100 */
    int tilt_angle;			/* absolute angle; 0,0 is home position */
    int snapshot_button_status;		/* set to 1 when the user push the button, reset to 0 when this value is read */
+   struct input_dev *button_dev;	/* webcam snapshot button input */
 
    /*** Misc. data ***/
    wait_queue_head_t frameq;		/* When waiting for a frame to finish... */
diff -uNr a/linux/drivers/media/video/pwc/pwc-if.c b/linux/drivers/media/video/pwc/pwc-if.c
--- a/linux/drivers/media/video/pwc/pwc-if.c	2009-01-03 20:03:43.000000000 +0700
+++ b/linux/drivers/media/video/pwc/pwc-if.c	2009-01-08 10:38:45.000000000 +0700
@@ -53,6 +53,7 @@
    - Xavier Roche: QuickCam Pro 4000 ID
    - Jens Knudsen: QuickCam Zoom ID
    - J. Debert: QuickCam for Notebooks ID
+   - Pham Thanh Nam: webcam snapshot button as an event input device
 */
 
 #include <linux/errno.h>
@@ -61,6 +62,11 @@
 #include <linux/module.h>
 #include <linux/poll.h>
 #include <linux/slab.h>
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 18)
+#include <linux/usb_input.h>
+#else
+#include <linux/usb/input.h>
+#endif
 #include <linux/vmalloc.h>
 #include <linux/version.h>
 #include <asm/io.h>
@@ -587,6 +593,22 @@
 				pdev->vframe_count);
 }
 
+static void pwc_snapshot_button(struct pwc_device *pdev, int down)
+{
+	if (down) {
+		PWC_TRACE("Snapshot button pressed.\n");
+		pdev->snapshot_button_status = 1;
+	}
+	else {
+		PWC_TRACE("Snapshot button released.\n");
+	}
+
+	if (pdev->button_dev) {
+		input_report_key(pdev->button_dev, BTN_0, down);
+		input_sync(pdev->button_dev);
+	}
+}
+
 static int pwc_rcv_short_packet(struct pwc_device *pdev, const struct pwc_frame_buf *fbuf)
 {
 	int awake = 0;
@@ -604,13 +626,7 @@
 			pdev->vframes_error++;
 		}
 		if ((ptr[0] ^ pdev->vmirror) & 0x01) {
-			if (ptr[0] & 0x01) {
-				pdev->snapshot_button_status = 1;
-				PWC_TRACE("Snapshot button pressed.\n");
-			}
-			else {
-				PWC_TRACE("Snapshot button released.\n");
-			}
+			pwc_snapshot_button(pdev, ptr[0] & 0x01);
 		}
 		if ((ptr[0] ^ pdev->vmirror) & 0x02) {
 			if (ptr[0] & 0x02)
@@ -634,12 +650,7 @@
 	else if (pdev->type == 740 || pdev->type == 720) {
 		unsigned char *ptr = (unsigned char *)fbuf->data;
 		if ((ptr[0] ^ pdev->vmirror) & 0x01) {
-			if (ptr[0] & 0x01) {
-				pdev->snapshot_button_status = 1;
-				PWC_TRACE("Snapshot button pressed.\n");
-			}
-			else
-				PWC_TRACE("Snapshot button released.\n");
+			pwc_snapshot_button(pdev, ptr[0] & 0x01);
 		}
 		pdev->vmirror = ptr[0] & 0x03;
 	}
@@ -1221,6 +1232,11 @@
 {
 	pwc_remove_sysfs_files(pdev->vdev);
 	video_unregister_device(pdev->vdev);
+	if (pdev->button_dev) {
+		input_unregister_device(pdev->button_dev);
+		input_free_device(pdev->button_dev);
+		pdev->button_dev = NULL;
+	}
 }
 
 /* Note that all cleanup is done in the reverse order as in _open */
@@ -1488,6 +1504,7 @@
 	int features = 0;
 	int video_nr = -1; /* default: use next available device */
 	char serial_number[30], *name;
+	char *phys = NULL;
 
 	vendor_id = le16_to_cpu(udev->descriptor.idVendor);
 	product_id = le16_to_cpu(udev->descriptor.idProduct);
@@ -1812,6 +1829,39 @@
 	pwc_set_leds(pdev, 0, 0);
 	pwc_camera_power(pdev, 0);
 
+	/* register webcam snapshot button input device */
+	pdev->button_dev = input_allocate_device();
+	if (!pdev->button_dev) {
+		PWC_ERROR("Err, insufficient memory for webcam snapshot button device.");
+		return -ENOMEM;
+	}
+
+	pdev->button_dev->name = "PWC snapshot button";
+	phys = kmalloc(6 + strlen(pdev->udev->bus->bus_name) + strlen(pdev->udev->devpath),
+			GFP_KERNEL);
+	if (phys == NULL) {
+		input_free_device(pdev->button_dev);
+		return -ENOMEM;
+	}
+
+	sprintf(phys, "usb-%s-%s", pdev->udev->bus->bus_name, pdev->udev->devpath);
+	pdev->button_dev->phys = phys;
+	usb_to_input_id(pdev->udev, &pdev->button_dev->id);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 22)
+	pdev->button_dev->dev.parent = &pdev->udev->dev;
+#else
+	pdev->button_dev->cdev.dev = &pdev->udev->dev;
+#endif
+	pdev->button_dev->evbit[0] = BIT_MASK(EV_KEY);
+	pdev->button_dev->keybit[BIT_WORD(BTN_0)] = BIT_MASK(BTN_0);
+
+	rc = input_register_device(pdev->button_dev);
+	if (rc) {
+		input_free_device(pdev->button_dev);
+		pdev->button_dev = NULL;
+		return rc;
+	}
+
 	return 0;
 
 err_unreg: