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From:   Oleksandr Andrushchenko <andr2000@gmail.com>
To:     xen-devel@lists.xenproject.org, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org, dmitry.torokhov@gmail.com,
        jgross@suse.com, lyan@suse.com, boris.ostrovsky@oracle.com
Cc:     andr2000@gmail.com, andrii_chepurnyi@epam.com,
        Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Subject: [PATCH] Input: xen-kbdfront - allow better run-time configuration
Date:   Wed, 18 Apr 2018 18:04:45 +0300
Message-Id: <20180418150445.9805-1-andr2000@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

It is now only possible to control if multi-touch virtual device
is created or not (via the corresponding XenStore entries),
but keyboard and pointer devices are always created.
In some cases this is not desirable. For example, if virtual
keyboard device is exposed to Android then the latter won't
automatically show on-screen keyboard as it expects that a
physical keyboard device can be used for typing.

Make it possible to configure which virtual devices are created
with module parameters:
  - no_ptr_dev=1 if no pointer device needs to be created
  - no_kbd_dev=1 if no keyboard device needs to be created
Keep old behavior by default.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Suggested-by: Andrii Chepurnyi <andrii_chepurnyi@epam.com>
Tested-by: Andrii Chepurnyi <andrii_chepurnyi@epam.com>
---
 drivers/input/misc/xen-kbdfront.c | 159 +++++++++++++++++-------------
 1 file changed, 92 insertions(+), 67 deletions(-)

diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
index d91f3b1c5375..a3306aad40b0 100644
--- a/drivers/input/misc/xen-kbdfront.c
+++ b/drivers/input/misc/xen-kbdfront.c
@@ -51,6 +51,16 @@ module_param_array(ptr_size, int, NULL, 0444);
 MODULE_PARM_DESC(ptr_size,
 	"Pointing device width, height in pixels (default 800,600)");
 
+static unsigned int no_ptr_dev;
+module_param(no_ptr_dev, uint, 0);
+MODULE_PARM_DESC(no_ptr_dev,
+	"If set then no virtual pointing device exposed to the guest");
+
+static unsigned int no_kbd_dev;
+module_param(no_kbd_dev, uint, 0);
+MODULE_PARM_DESC(no_kbd_dev,
+	"If set then no virtual keyboard device exposed to the guest");
+
 static int xenkbd_remove(struct xenbus_device *);
 static int xenkbd_connect_backend(struct xenbus_device *, struct xenkbd_info *);
 static void xenkbd_disconnect_backend(struct xenkbd_info *);
@@ -63,6 +73,9 @@ static void xenkbd_disconnect_backend(struct xenkbd_info *);
 static void xenkbd_handle_motion_event(struct xenkbd_info *info,
 				       struct xenkbd_motion *motion)
 {
+	if (unlikely(!info->ptr))
+		return;
+
 	input_report_rel(info->ptr, REL_X, motion->rel_x);
 	input_report_rel(info->ptr, REL_Y, motion->rel_y);
 	if (motion->rel_z)
@@ -73,6 +86,9 @@ static void xenkbd_handle_motion_event(struct xenkbd_info *info,
 static void xenkbd_handle_position_event(struct xenkbd_info *info,
 					 struct xenkbd_position *pos)
 {
+	if (unlikely(!info->ptr))
+		return;
+
 	input_report_abs(info->ptr, ABS_X, pos->abs_x);
 	input_report_abs(info->ptr, ABS_Y, pos->abs_y);
 	if (pos->rel_z)
@@ -97,6 +113,9 @@ static void xenkbd_handle_key_event(struct xenkbd_info *info,
 		return;
 	}
 
+	if (unlikely(!dev))
+		return;
+
 	input_event(dev, EV_KEY, key->keycode, value);
 	input_sync(dev);
 }
@@ -192,7 +211,7 @@ static int xenkbd_probe(struct xenbus_device *dev,
 				  const struct xenbus_device_id *id)
 {
 	int ret, i;
-	unsigned int abs, touch;
+	unsigned int touch;
 	struct xenkbd_info *info;
 	struct input_dev *kbd, *ptr, *mtouch;
 
@@ -211,24 +230,6 @@ static int xenkbd_probe(struct xenbus_device *dev,
 	if (!info->page)
 		goto error_nomem;
 
-	/* Set input abs params to match backend screen res */
-	abs = xenbus_read_unsigned(dev->otherend,
-				   XENKBD_FIELD_FEAT_ABS_POINTER, 0);
-	ptr_size[KPARAM_X] = xenbus_read_unsigned(dev->otherend,
-						  XENKBD_FIELD_WIDTH,
-						  ptr_size[KPARAM_X]);
-	ptr_size[KPARAM_Y] = xenbus_read_unsigned(dev->otherend,
-						  XENKBD_FIELD_HEIGHT,
-						  ptr_size[KPARAM_Y]);
-	if (abs) {
-		ret = xenbus_write(XBT_NIL, dev->nodename,
-				   XENKBD_FIELD_REQ_ABS_POINTER, "1");
-		if (ret) {
-			pr_warn("xenkbd: can't request abs-pointer\n");
-			abs = 0;
-		}
-	}
-
 	touch = xenbus_read_unsigned(dev->nodename,
 				     XENKBD_FIELD_FEAT_MTOUCH, 0);
 	if (touch) {
@@ -241,60 +242,84 @@ static int xenkbd_probe(struct xenbus_device *dev,
 	}
 
 	/* keyboard */
-	kbd = input_allocate_device();
-	if (!kbd)
-		goto error_nomem;
-	kbd->name = "Xen Virtual Keyboard";
-	kbd->phys = info->phys;
-	kbd->id.bustype = BUS_PCI;
-	kbd->id.vendor = 0x5853;
-	kbd->id.product = 0xffff;
-
-	__set_bit(EV_KEY, kbd->evbit);
-	for (i = KEY_ESC; i < KEY_UNKNOWN; i++)
-		__set_bit(i, kbd->keybit);
-	for (i = KEY_OK; i < KEY_MAX; i++)
-		__set_bit(i, kbd->keybit);
-
-	ret = input_register_device(kbd);
-	if (ret) {
-		input_free_device(kbd);
-		xenbus_dev_fatal(dev, ret, "input_register_device(kbd)");
-		goto error;
+	if (!no_kbd_dev) {
+		kbd = input_allocate_device();
+		if (!kbd)
+			goto error_nomem;
+		kbd->name = "Xen Virtual Keyboard";
+		kbd->phys = info->phys;
+		kbd->id.bustype = BUS_PCI;
+		kbd->id.vendor = 0x5853;
+		kbd->id.product = 0xffff;
+
+		__set_bit(EV_KEY, kbd->evbit);
+		for (i = KEY_ESC; i < KEY_UNKNOWN; i++)
+			__set_bit(i, kbd->keybit);
+		for (i = KEY_OK; i < KEY_MAX; i++)
+			__set_bit(i, kbd->keybit);
+
+		ret = input_register_device(kbd);
+		if (ret) {
+			input_free_device(kbd);
+			xenbus_dev_fatal(dev, ret, "input_register_device(kbd)");
+			goto error;
+		}
+		info->kbd = kbd;
 	}
-	info->kbd = kbd;
 
 	/* pointing device */
-	ptr = input_allocate_device();
-	if (!ptr)
-		goto error_nomem;
-	ptr->name = "Xen Virtual Pointer";
-	ptr->phys = info->phys;
-	ptr->id.bustype = BUS_PCI;
-	ptr->id.vendor = 0x5853;
-	ptr->id.product = 0xfffe;
-
-	if (abs) {
-		__set_bit(EV_ABS, ptr->evbit);
-		input_set_abs_params(ptr, ABS_X, 0, ptr_size[KPARAM_X], 0, 0);
-		input_set_abs_params(ptr, ABS_Y, 0, ptr_size[KPARAM_Y], 0, 0);
-	} else {
-		input_set_capability(ptr, EV_REL, REL_X);
-		input_set_capability(ptr, EV_REL, REL_Y);
-	}
-	input_set_capability(ptr, EV_REL, REL_WHEEL);
+	if (!no_ptr_dev) {
+		unsigned int abs;
+
+		/* Set input abs params to match backend screen res */
+		abs = xenbus_read_unsigned(dev->otherend,
+					   XENKBD_FIELD_FEAT_ABS_POINTER, 0);
+		ptr_size[KPARAM_X] = xenbus_read_unsigned(dev->otherend,
+							  XENKBD_FIELD_WIDTH,
+							  ptr_size[KPARAM_X]);
+		ptr_size[KPARAM_Y] = xenbus_read_unsigned(dev->otherend,
+							  XENKBD_FIELD_HEIGHT,
+							  ptr_size[KPARAM_Y]);
+		if (abs) {
+			ret = xenbus_write(XBT_NIL, dev->nodename,
+					   XENKBD_FIELD_REQ_ABS_POINTER, "1");
+			if (ret) {
+				pr_warn("xenkbd: can't request abs-pointer\n");
+				abs = 0;
+			}
+		}
 
-	__set_bit(EV_KEY, ptr->evbit);
-	for (i = BTN_LEFT; i <= BTN_TASK; i++)
-		__set_bit(i, ptr->keybit);
+		ptr = input_allocate_device();
+		if (!ptr)
+			goto error_nomem;
+		ptr->name = "Xen Virtual Pointer";
+		ptr->phys = info->phys;
+		ptr->id.bustype = BUS_PCI;
+		ptr->id.vendor = 0x5853;
+		ptr->id.product = 0xfffe;
+
+		if (abs) {
+			__set_bit(EV_ABS, ptr->evbit);
+			input_set_abs_params(ptr, ABS_X, 0, ptr_size[KPARAM_X], 0, 0);
+			input_set_abs_params(ptr, ABS_Y, 0, ptr_size[KPARAM_Y], 0, 0);
+		} else {
+			input_set_capability(ptr, EV_REL, REL_X);
+			input_set_capability(ptr, EV_REL, REL_Y);
+		}
+		input_set_capability(ptr, EV_REL, REL_WHEEL);
 
-	ret = input_register_device(ptr);
-	if (ret) {
-		input_free_device(ptr);
-		xenbus_dev_fatal(dev, ret, "input_register_device(ptr)");
-		goto error;
+		__set_bit(EV_KEY, ptr->evbit);
+		for (i = BTN_LEFT; i <= BTN_TASK; i++)
+			__set_bit(i, ptr->keybit);
+
+		ret = input_register_device(ptr);
+		if (ret) {
+			input_free_device(ptr);
+			xenbus_dev_fatal(dev, ret, "input_register_device(ptr)");
+			goto error;
+		}
+		info->ptr = ptr;
 	}
-	info->ptr = ptr;
 
 	/* multi-touch device */
 	if (touch) {
-- 
2.17.0