xen pvfb: Para-virtual framebuffer, keyboard and pointer driver

This is a pair of Xen para-virtual frontend device drivers:
drivers/video/xen-fbfront.c provides a framebuffer, and
drivers/input/xen-kbdfront provides keyboard and mouse.

The backends run in dom0 user space.

The two drivers are not in two separate patches, because the
intermediate step (one driver, not the other) is somewhat problematic:
the backend in dom0 needs both drivers, and will refuse to complete
device initialization unless they're both present.

Signed-off-by: Markus Armbruster <armbru@redhat.com>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 351 insertions, 0 deletions

diff --git a/drivers/input/Kconfig b/drivers/input/Kconfig
index 9dea14db724c..5f9d860925a1 100644
--- a/drivers/input/Kconfig
+++ b/drivers/input/Kconfig
@@ -149,6 +149,15 @@ config INPUT_APMPOWER
 	  To compile this driver as a module, choose M here: the
 	  module will be called apm-power.
 
+config XEN_KBDDEV_FRONTEND
+	tristate "Xen virtual keyboard and mouse support"
+	depends on XEN_FBDEV_FRONTEND
+	default y
+	help
+	  This driver implements the front-end of the Xen virtual
+	  keyboard and mouse device driver.  It communicates with a back-end
+	  in another domain.
+
 comment "Input Device Drivers"
 
 source "drivers/input/keyboard/Kconfig"
diff --git a/drivers/input/Makefile b/drivers/input/Makefile
index 2ae87b19caa8..98c4f9a77876 100644
--- a/drivers/input/Makefile
+++ b/drivers/input/Makefile
@@ -23,3 +23,5 @@ obj-$(CONFIG_INPUT_TOUCHSCREEN)	+= touchscreen/
 obj-$(CONFIG_INPUT_MISC)	+= misc/
 
 obj-$(CONFIG_INPUT_APMPOWER)	+= apm-power.o
+
+obj-$(CONFIG_XEN_KBDDEV_FRONTEND)	+= xen-kbdfront.o
diff --git a/drivers/input/xen-kbdfront.c b/drivers/input/xen-kbdfront.c
new file mode 100644
index 000000000000..0f47f4697cdf
--- /dev/null
+++ b/drivers/input/xen-kbdfront.c
@@ -0,0 +1,340 @@
+/*
+ * Xen para-virtual input device
+ *
+ * Copyright (C) 2005 Anthony Liguori <aliguori@us.ibm.com>
+ * Copyright (C) 2006-2008 Red Hat, Inc., Markus Armbruster <armbru@redhat.com>
+ *
+ *  Based on linux/drivers/input/mouse/sermouse.c
+ *
+ *  This file is subject to the terms and conditions of the GNU General Public
+ *  License. See the file COPYING in the main directory of this archive for
+ *  more details.
+ */
+
+/*
+ * TODO:
+ *
+ * Switch to grant tables together with xen-fbfront.c.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/input.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/events.h>
+#include <xen/page.h>
+#include <xen/interface/io/fbif.h>
+#include <xen/interface/io/kbdif.h>
+#include <xen/xenbus.h>
+
+struct xenkbd_info {
+	struct input_dev *kbd;
+	struct input_dev *ptr;
+	struct xenkbd_page *page;
+	int irq;
+	struct xenbus_device *xbdev;
+	char phys[32];
+};
+
+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 *);
+
+/*
+ * Note: if you need to send out events, see xenfb_do_update() for how
+ * to do that.
+ */
+
+static irqreturn_t input_handler(int rq, void *dev_id)
+{
+	struct xenkbd_info *info = dev_id;
+	struct xenkbd_page *page = info->page;
+	__u32 cons, prod;
+
+	prod = page->in_prod;
+	if (prod == page->in_cons)
+		return IRQ_HANDLED;
+	rmb();			/* ensure we see ring contents up to prod */
+	for (cons = page->in_cons; cons != prod; cons++) {
+		union xenkbd_in_event *event;
+		struct input_dev *dev;
+		event = &XENKBD_IN_RING_REF(page, cons);
+
+		dev = info->ptr;
+		switch (event->type) {
+		case XENKBD_TYPE_MOTION:
+			input_report_rel(dev, REL_X, event->motion.rel_x);
+			input_report_rel(dev, REL_Y, event->motion.rel_y);
+			break;
+		case XENKBD_TYPE_KEY:
+			dev = NULL;
+			if (test_bit(event->key.keycode, info->kbd->keybit))
+				dev = info->kbd;
+			if (test_bit(event->key.keycode, info->ptr->keybit))
+				dev = info->ptr;
+			if (dev)
+				input_report_key(dev, event->key.keycode,
+						 event->key.pressed);
+			else
+				printk(KERN_WARNING
+				       "xenkbd: unhandled keycode 0x%x\n",
+				       event->key.keycode);
+			break;
+		case XENKBD_TYPE_POS:
+			input_report_abs(dev, ABS_X, event->pos.abs_x);
+			input_report_abs(dev, ABS_Y, event->pos.abs_y);
+			break;
+		}
+		if (dev)
+			input_sync(dev);
+	}
+	mb();			/* ensure we got ring contents */
+	page->in_cons = cons;
+	notify_remote_via_irq(info->irq);
+
+	return IRQ_HANDLED;
+}
+
+static int __devinit xenkbd_probe(struct xenbus_device *dev,
+				  const struct xenbus_device_id *id)
+{
+	int ret, i;
+	struct xenkbd_info *info;
+	struct input_dev *kbd, *ptr;
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info) {
+		xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
+		return -ENOMEM;
+	}
+	dev->dev.driver_data = info;
+	info->xbdev = dev;
+	info->irq = -1;
+	snprintf(info->phys, sizeof(info->phys), "xenbus/%s", dev->nodename);
+
+	info->page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+	if (!info->page)
+		goto error_nomem;
+
+	/* 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;
+	kbd->evbit[0] = BIT(EV_KEY);
+	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;
+
+	/* 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;
+	ptr->evbit[0] = BIT(EV_KEY) | BIT(EV_REL) | BIT(EV_ABS);
+	for (i = BTN_LEFT; i <= BTN_TASK; i++)
+		set_bit(i, ptr->keybit);
+	ptr->relbit[0] = BIT(REL_X) | BIT(REL_Y);
+	input_set_abs_params(ptr, ABS_X, 0, XENFB_WIDTH, 0, 0);
+	input_set_abs_params(ptr, ABS_Y, 0, XENFB_HEIGHT, 0, 0);
+
+	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;
+
+	ret = xenkbd_connect_backend(dev, info);
+	if (ret < 0)
+		goto error;
+
+	return 0;
+
+ error_nomem:
+	ret = -ENOMEM;
+	xenbus_dev_fatal(dev, ret, "allocating device memory");
+ error:
+	xenkbd_remove(dev);
+	return ret;
+}
+
+static int xenkbd_resume(struct xenbus_device *dev)
+{
+	struct xenkbd_info *info = dev->dev.driver_data;
+
+	xenkbd_disconnect_backend(info);
+	memset(info->page, 0, PAGE_SIZE);
+	return xenkbd_connect_backend(dev, info);
+}
+
+static int xenkbd_remove(struct xenbus_device *dev)
+{
+	struct xenkbd_info *info = dev->dev.driver_data;
+
+	xenkbd_disconnect_backend(info);
+	if (info->kbd)
+		input_unregister_device(info->kbd);
+	if (info->ptr)
+		input_unregister_device(info->ptr);
+	free_page((unsigned long)info->page);
+	kfree(info);
+	return 0;
+}
+
+static int xenkbd_connect_backend(struct xenbus_device *dev,
+				  struct xenkbd_info *info)
+{
+	int ret, evtchn;
+	struct xenbus_transaction xbt;
+
+	ret = xenbus_alloc_evtchn(dev, &evtchn);
+	if (ret)
+		return ret;
+	ret = bind_evtchn_to_irqhandler(evtchn, input_handler,
+					0, dev->devicetype, info);
+	if (ret < 0) {
+		xenbus_free_evtchn(dev, evtchn);
+		xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler");
+		return ret;
+	}
+	info->irq = ret;
+
+ again:
+	ret = xenbus_transaction_start(&xbt);
+	if (ret) {
+		xenbus_dev_fatal(dev, ret, "starting transaction");
+		return ret;
+	}
+	ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu",
+			    virt_to_mfn(info->page));
+	if (ret)
+		goto error_xenbus;
+	ret = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
+			    evtchn);
+	if (ret)
+		goto error_xenbus;
+	ret = xenbus_transaction_end(xbt, 0);
+	if (ret) {
+		if (ret == -EAGAIN)
+			goto again;
+		xenbus_dev_fatal(dev, ret, "completing transaction");
+		return ret;
+	}
+
+	xenbus_switch_state(dev, XenbusStateInitialised);
+	return 0;
+
+ error_xenbus:
+	xenbus_transaction_end(xbt, 1);
+	xenbus_dev_fatal(dev, ret, "writing xenstore");
+	return ret;
+}
+
+static void xenkbd_disconnect_backend(struct xenkbd_info *info)
+{
+	if (info->irq >= 0)
+		unbind_from_irqhandler(info->irq, info);
+	info->irq = -1;
+}
+
+static void xenkbd_backend_changed(struct xenbus_device *dev,
+				   enum xenbus_state backend_state)
+{
+	struct xenkbd_info *info = dev->dev.driver_data;
+	int ret, val;
+
+	switch (backend_state) {
+	case XenbusStateInitialising:
+	case XenbusStateInitialised:
+	case XenbusStateUnknown:
+	case XenbusStateClosed:
+		break;
+
+	case XenbusStateInitWait:
+InitWait:
+		ret = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+				   "feature-abs-pointer", "%d", &val);
+		if (ret < 0)
+			val = 0;
+		if (val) {
+			ret = xenbus_printf(XBT_NIL, info->xbdev->nodename,
+					    "request-abs-pointer", "1");
+			if (ret)
+				printk(KERN_WARNING
+				       "xenkbd: can't request abs-pointer");
+		}
+		xenbus_switch_state(dev, XenbusStateConnected);
+		break;
+
+	case XenbusStateConnected:
+		/*
+		 * Work around xenbus race condition: If backend goes
+		 * through InitWait to Connected fast enough, we can
+		 * get Connected twice here.
+		 */
+		if (dev->state != XenbusStateConnected)
+			goto InitWait; /* no InitWait seen yet, fudge it */
+		break;
+
+	case XenbusStateClosing:
+		xenbus_frontend_closed(dev);
+		break;
+	}
+}
+
+static struct xenbus_device_id xenkbd_ids[] = {
+	{ "vkbd" },
+	{ "" }
+};
+
+static struct xenbus_driver xenkbd = {
+	.name = "vkbd",
+	.owner = THIS_MODULE,
+	.ids = xenkbd_ids,
+	.probe = xenkbd_probe,
+	.remove = xenkbd_remove,
+	.resume = xenkbd_resume,
+	.otherend_changed = xenkbd_backend_changed,
+};
+
+static int __init xenkbd_init(void)
+{
+	if (!is_running_on_xen())
+		return -ENODEV;
+
+	/* Nothing to do if running in dom0. */
+	if (is_initial_xendomain())
+		return -ENODEV;
+
+	return xenbus_register_frontend(&xenkbd);
+}
+
+static void __exit xenkbd_cleanup(void)
+{
+	xenbus_unregister_driver(&xenkbd);
+}
+
+module_init(xenkbd_init);
+module_exit(xenkbd_cleanup);
+
+MODULE_LICENSE("GPL");