Moved, renamed, and deleted files

The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.

1 files changed, 713 insertions, 0 deletions

diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c
new file mode 100644
index 00000000..b7f5173f
--- /dev/null
+++ b/drivers/video/xen-fbfront.c
@@ -0,0 +1,713 @@
+/*
+ * Xen para-virtual frame buffer device
+ *
+ * Copyright (C) 2005-2006 Anthony Liguori <aliguori@us.ibm.com>
+ * Copyright (C) 2006-2008 Red Hat, Inc., Markus Armbruster <armbru@redhat.com>
+ *
+ *  Based on linux/drivers/video/q40fb.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 when they become capable of dealing with the
+ * frame buffer.
+ */
+
+#include <linux/console.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/fb.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+
+#include <asm/xen/hypervisor.h>
+
+#include <xen/xen.h>
+#include <xen/events.h>
+#include <xen/page.h>
+#include <xen/interface/io/fbif.h>
+#include <xen/interface/io/protocols.h>
+#include <xen/xenbus.h>
+
+struct xenfb_info {
+	unsigned char		*fb;
+	struct fb_info		*fb_info;
+	int			x1, y1, x2, y2;	/* dirty rectangle,
+						   protected by dirty_lock */
+	spinlock_t		dirty_lock;
+	int			nr_pages;
+	int			irq;
+	struct xenfb_page	*page;
+	unsigned long 		*mfns;
+	int			update_wanted; /* XENFB_TYPE_UPDATE wanted */
+	int			feature_resize; /* XENFB_TYPE_RESIZE ok */
+	struct xenfb_resize	resize;		/* protected by resize_lock */
+	int			resize_dpy;	/* ditto */
+	spinlock_t		resize_lock;
+
+	struct xenbus_device	*xbdev;
+};
+
+#define XENFB_DEFAULT_FB_LEN (XENFB_WIDTH * XENFB_HEIGHT * XENFB_DEPTH / 8)
+
+enum { KPARAM_MEM, KPARAM_WIDTH, KPARAM_HEIGHT, KPARAM_CNT };
+static int video[KPARAM_CNT] = { 2, XENFB_WIDTH, XENFB_HEIGHT };
+module_param_array(video, int, NULL, 0);
+MODULE_PARM_DESC(video,
+	"Video memory size in MB, width, height in pixels (default 2,800,600)");
+
+static void xenfb_make_preferred_console(void);
+static int xenfb_remove(struct xenbus_device *);
+static void xenfb_init_shared_page(struct xenfb_info *, struct fb_info *);
+static int xenfb_connect_backend(struct xenbus_device *, struct xenfb_info *);
+static void xenfb_disconnect_backend(struct xenfb_info *);
+
+static void xenfb_send_event(struct xenfb_info *info,
+			     union xenfb_out_event *event)
+{
+	u32 prod;
+
+	prod = info->page->out_prod;
+	/* caller ensures !xenfb_queue_full() */
+	mb();			/* ensure ring space available */
+	XENFB_OUT_RING_REF(info->page, prod) = *event;
+	wmb();			/* ensure ring contents visible */
+	info->page->out_prod = prod + 1;
+
+	notify_remote_via_irq(info->irq);
+}
+
+static void xenfb_do_update(struct xenfb_info *info,
+			    int x, int y, int w, int h)
+{
+	union xenfb_out_event event;
+
+	memset(&event, 0, sizeof(event));
+	event.type = XENFB_TYPE_UPDATE;
+	event.update.x = x;
+	event.update.y = y;
+	event.update.width = w;
+	event.update.height = h;
+
+	/* caller ensures !xenfb_queue_full() */
+	xenfb_send_event(info, &event);
+}
+
+static void xenfb_do_resize(struct xenfb_info *info)
+{
+	union xenfb_out_event event;
+
+	memset(&event, 0, sizeof(event));
+	event.resize = info->resize;
+
+	/* caller ensures !xenfb_queue_full() */
+	xenfb_send_event(info, &event);
+}
+
+static int xenfb_queue_full(struct xenfb_info *info)
+{
+	u32 cons, prod;
+
+	prod = info->page->out_prod;
+	cons = info->page->out_cons;
+	return prod - cons == XENFB_OUT_RING_LEN;
+}
+
+static void xenfb_handle_resize_dpy(struct xenfb_info *info)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&info->resize_lock, flags);
+	if (info->resize_dpy) {
+		if (!xenfb_queue_full(info)) {
+			info->resize_dpy = 0;
+			xenfb_do_resize(info);
+		}
+	}
+	spin_unlock_irqrestore(&info->resize_lock, flags);
+}
+
+static void xenfb_refresh(struct xenfb_info *info,
+			  int x1, int y1, int w, int h)
+{
+	unsigned long flags;
+	int x2 = x1 + w - 1;
+	int y2 = y1 + h - 1;
+
+	xenfb_handle_resize_dpy(info);
+
+	if (!info->update_wanted)
+		return;
+
+	spin_lock_irqsave(&info->dirty_lock, flags);
+
+	/* Combine with dirty rectangle: */
+	if (info->y1 < y1)
+		y1 = info->y1;
+	if (info->y2 > y2)
+		y2 = info->y2;
+	if (info->x1 < x1)
+		x1 = info->x1;
+	if (info->x2 > x2)
+		x2 = info->x2;
+
+	if (xenfb_queue_full(info)) {
+		/* Can't send right now, stash it in the dirty rectangle */
+		info->x1 = x1;
+		info->x2 = x2;
+		info->y1 = y1;
+		info->y2 = y2;
+		spin_unlock_irqrestore(&info->dirty_lock, flags);
+		return;
+	}
+
+	/* Clear dirty rectangle: */
+	info->x1 = info->y1 = INT_MAX;
+	info->x2 = info->y2 = 0;
+
+	spin_unlock_irqrestore(&info->dirty_lock, flags);
+
+	if (x1 <= x2 && y1 <= y2)
+		xenfb_do_update(info, x1, y1, x2 - x1 + 1, y2 - y1 + 1);
+}
+
+static void xenfb_deferred_io(struct fb_info *fb_info,
+			      struct list_head *pagelist)
+{
+	struct xenfb_info *info = fb_info->par;
+	struct page *page;
+	unsigned long beg, end;
+	int y1, y2, miny, maxy;
+
+	miny = INT_MAX;
+	maxy = 0;
+	list_for_each_entry(page, pagelist, lru) {
+		beg = page->index << PAGE_SHIFT;
+		end = beg + PAGE_SIZE - 1;
+		y1 = beg / fb_info->fix.line_length;
+		y2 = end / fb_info->fix.line_length;
+		if (y2 >= fb_info->var.yres)
+			y2 = fb_info->var.yres - 1;
+		if (miny > y1)
+			miny = y1;
+		if (maxy < y2)
+			maxy = y2;
+	}
+	xenfb_refresh(info, 0, miny, fb_info->var.xres, maxy - miny + 1);
+}
+
+static struct fb_deferred_io xenfb_defio = {
+	.delay		= HZ / 20,
+	.deferred_io	= xenfb_deferred_io,
+};
+
+static int xenfb_setcolreg(unsigned regno, unsigned red, unsigned green,
+			   unsigned blue, unsigned transp,
+			   struct fb_info *info)
+{
+	u32 v;
+
+	if (regno > info->cmap.len)
+		return 1;
+
+#define CNVT_TOHW(val, width) ((((val)<<(width))+0x7FFF-(val))>>16)
+	red = CNVT_TOHW(red, info->var.red.length);
+	green = CNVT_TOHW(green, info->var.green.length);
+	blue = CNVT_TOHW(blue, info->var.blue.length);
+	transp = CNVT_TOHW(transp, info->var.transp.length);
+#undef CNVT_TOHW
+
+	v = (red << info->var.red.offset) |
+	    (green << info->var.green.offset) |
+	    (blue << info->var.blue.offset);
+
+	switch (info->var.bits_per_pixel) {
+	case 16:
+	case 24:
+	case 32:
+		((u32 *)info->pseudo_palette)[regno] = v;
+		break;
+	}
+
+	return 0;
+}
+
+static void xenfb_fillrect(struct fb_info *p, const struct fb_fillrect *rect)
+{
+	struct xenfb_info *info = p->par;
+
+	sys_fillrect(p, rect);
+	xenfb_refresh(info, rect->dx, rect->dy, rect->width, rect->height);
+}
+
+static void xenfb_imageblit(struct fb_info *p, const struct fb_image *image)
+{
+	struct xenfb_info *info = p->par;
+
+	sys_imageblit(p, image);
+	xenfb_refresh(info, image->dx, image->dy, image->width, image->height);
+}
+
+static void xenfb_copyarea(struct fb_info *p, const struct fb_copyarea *area)
+{
+	struct xenfb_info *info = p->par;
+
+	sys_copyarea(p, area);
+	xenfb_refresh(info, area->dx, area->dy, area->width, area->height);
+}
+
+static ssize_t xenfb_write(struct fb_info *p, const char __user *buf,
+			size_t count, loff_t *ppos)
+{
+	struct xenfb_info *info = p->par;
+	ssize_t res;
+
+	res = fb_sys_write(p, buf, count, ppos);
+	xenfb_refresh(info, 0, 0, info->page->width, info->page->height);
+	return res;
+}
+
+static int
+xenfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
+{
+	struct xenfb_info *xenfb_info;
+	int required_mem_len;
+
+	xenfb_info = info->par;
+
+	if (!xenfb_info->feature_resize) {
+		if (var->xres == video[KPARAM_WIDTH] &&
+		    var->yres == video[KPARAM_HEIGHT] &&
+		    var->bits_per_pixel == xenfb_info->page->depth) {
+			return 0;
+		}
+		return -EINVAL;
+	}
+
+	/* Can't resize past initial width and height */
+	if (var->xres > video[KPARAM_WIDTH] || var->yres > video[KPARAM_HEIGHT])
+		return -EINVAL;
+
+	required_mem_len = var->xres * var->yres * xenfb_info->page->depth / 8;
+	if (var->bits_per_pixel == xenfb_info->page->depth &&
+	    var->xres <= info->fix.line_length / (XENFB_DEPTH / 8) &&
+	    required_mem_len <= info->fix.smem_len) {
+		var->xres_virtual = var->xres;
+		var->yres_virtual = var->yres;
+		return 0;
+	}
+	return -EINVAL;
+}
+
+static int xenfb_set_par(struct fb_info *info)
+{
+	struct xenfb_info *xenfb_info;
+	unsigned long flags;
+
+	xenfb_info = info->par;
+
+	spin_lock_irqsave(&xenfb_info->resize_lock, flags);
+	xenfb_info->resize.type = XENFB_TYPE_RESIZE;
+	xenfb_info->resize.width = info->var.xres;
+	xenfb_info->resize.height = info->var.yres;
+	xenfb_info->resize.stride = info->fix.line_length;
+	xenfb_info->resize.depth = info->var.bits_per_pixel;
+	xenfb_info->resize.offset = 0;
+	xenfb_info->resize_dpy = 1;
+	spin_unlock_irqrestore(&xenfb_info->resize_lock, flags);
+	return 0;
+}
+
+static struct fb_ops xenfb_fb_ops = {
+	.owner		= THIS_MODULE,
+	.fb_read	= fb_sys_read,
+	.fb_write	= xenfb_write,
+	.fb_setcolreg	= xenfb_setcolreg,
+	.fb_fillrect	= xenfb_fillrect,
+	.fb_copyarea	= xenfb_copyarea,
+	.fb_imageblit	= xenfb_imageblit,
+	.fb_check_var	= xenfb_check_var,
+	.fb_set_par     = xenfb_set_par,
+};
+
+static irqreturn_t xenfb_event_handler(int rq, void *dev_id)
+{
+	/*
+	 * No in events recognized, simply ignore them all.
+	 * If you need to recognize some, see xen-kbdfront's
+	 * input_handler() for how to do that.
+	 */
+	struct xenfb_info *info = dev_id;
+	struct xenfb_page *page = info->page;
+
+	if (page->in_cons != page->in_prod) {
+		info->page->in_cons = info->page->in_prod;
+		notify_remote_via_irq(info->irq);
+	}
+
+	/* Flush dirty rectangle: */
+	xenfb_refresh(info, INT_MAX, INT_MAX, -INT_MAX, -INT_MAX);
+
+	return IRQ_HANDLED;
+}
+
+static int __devinit xenfb_probe(struct xenbus_device *dev,
+				 const struct xenbus_device_id *id)
+{
+	struct xenfb_info *info;
+	struct fb_info *fb_info;
+	int fb_size;
+	int val;
+	int ret = 0;
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (info == NULL) {
+		xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
+		return -ENOMEM;
+	}
+
+	/* Limit kernel param videoram amount to what is in xenstore */
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "videoram", "%d", &val) == 1) {
+		if (val < video[KPARAM_MEM])
+			video[KPARAM_MEM] = val;
+	}
+
+	/* If requested res does not fit in available memory, use default */
+	fb_size = video[KPARAM_MEM] * 1024 * 1024;
+	if (video[KPARAM_WIDTH] * video[KPARAM_HEIGHT] * XENFB_DEPTH / 8
+	    > fb_size) {
+		video[KPARAM_WIDTH] = XENFB_WIDTH;
+		video[KPARAM_HEIGHT] = XENFB_HEIGHT;
+		fb_size = XENFB_DEFAULT_FB_LEN;
+	}
+
+	dev_set_drvdata(&dev->dev, info);
+	info->xbdev = dev;
+	info->irq = -1;
+	info->x1 = info->y1 = INT_MAX;
+	spin_lock_init(&info->dirty_lock);
+	spin_lock_init(&info->resize_lock);
+
+	info->fb = vzalloc(fb_size);
+	if (info->fb == NULL)
+		goto error_nomem;
+
+	info->nr_pages = (fb_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+	info->mfns = vmalloc(sizeof(unsigned long) * info->nr_pages);
+	if (!info->mfns)
+		goto error_nomem;
+
+	/* set up shared page */
+	info->page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+	if (!info->page)
+		goto error_nomem;
+
+	/* abusing framebuffer_alloc() to allocate pseudo_palette */
+	fb_info = framebuffer_alloc(sizeof(u32) * 256, NULL);
+	if (fb_info == NULL)
+		goto error_nomem;
+
+	/* complete the abuse: */
+	fb_info->pseudo_palette = fb_info->par;
+	fb_info->par = info;
+
+	fb_info->screen_base = info->fb;
+
+	fb_info->fbops = &xenfb_fb_ops;
+	fb_info->var.xres_virtual = fb_info->var.xres = video[KPARAM_WIDTH];
+	fb_info->var.yres_virtual = fb_info->var.yres = video[KPARAM_HEIGHT];
+	fb_info->var.bits_per_pixel = XENFB_DEPTH;
+
+	fb_info->var.red = (struct fb_bitfield){16, 8, 0};
+	fb_info->var.green = (struct fb_bitfield){8, 8, 0};
+	fb_info->var.blue = (struct fb_bitfield){0, 8, 0};
+
+	fb_info->var.activate = FB_ACTIVATE_NOW;
+	fb_info->var.height = -1;
+	fb_info->var.width = -1;
+	fb_info->var.vmode = FB_VMODE_NONINTERLACED;
+
+	fb_info->fix.visual = FB_VISUAL_TRUECOLOR;
+	fb_info->fix.line_length = fb_info->var.xres * XENFB_DEPTH / 8;
+	fb_info->fix.smem_start = 0;
+	fb_info->fix.smem_len = fb_size;
+	strcpy(fb_info->fix.id, "xen");
+	fb_info->fix.type = FB_TYPE_PACKED_PIXELS;
+	fb_info->fix.accel = FB_ACCEL_NONE;
+
+	fb_info->flags = FBINFO_FLAG_DEFAULT | FBINFO_VIRTFB;
+
+	ret = fb_alloc_cmap(&fb_info->cmap, 256, 0);
+	if (ret < 0) {
+		framebuffer_release(fb_info);
+		xenbus_dev_fatal(dev, ret, "fb_alloc_cmap");
+		goto error;
+	}
+
+	fb_info->fbdefio = &xenfb_defio;
+	fb_deferred_io_init(fb_info);
+
+	xenfb_init_shared_page(info, fb_info);
+
+	ret = xenfb_connect_backend(dev, info);
+	if (ret < 0) {
+		xenbus_dev_fatal(dev, ret, "xenfb_connect_backend");
+		goto error_fb;
+	}
+
+	ret = register_framebuffer(fb_info);
+	if (ret) {
+		xenbus_dev_fatal(dev, ret, "register_framebuffer");
+		goto error_fb;
+	}
+	info->fb_info = fb_info;
+
+	xenfb_make_preferred_console();
+	return 0;
+
+error_fb:
+	fb_deferred_io_cleanup(fb_info);
+	fb_dealloc_cmap(&fb_info->cmap);
+	framebuffer_release(fb_info);
+error_nomem:
+	if (!ret) {
+		ret = -ENOMEM;
+		xenbus_dev_fatal(dev, ret, "allocating device memory");
+	}
+error:
+	xenfb_remove(dev);
+	return ret;
+}
+
+static __devinit void
+xenfb_make_preferred_console(void)
+{
+	struct console *c;
+
+	if (console_set_on_cmdline)
+		return;
+
+	console_lock();
+	for_each_console(c) {
+		if (!strcmp(c->name, "tty") && c->index == 0)
+			break;
+	}
+	console_unlock();
+	if (c) {
+		unregister_console(c);
+		c->flags |= CON_CONSDEV;
+		c->flags &= ~CON_PRINTBUFFER; /* don't print again */
+		register_console(c);
+	}
+}
+
+static int xenfb_resume(struct xenbus_device *dev)
+{
+	struct xenfb_info *info = dev_get_drvdata(&dev->dev);
+
+	xenfb_disconnect_backend(info);
+	xenfb_init_shared_page(info, info->fb_info);
+	return xenfb_connect_backend(dev, info);
+}
+
+static int xenfb_remove(struct xenbus_device *dev)
+{
+	struct xenfb_info *info = dev_get_drvdata(&dev->dev);
+
+	xenfb_disconnect_backend(info);
+	if (info->fb_info) {
+		fb_deferred_io_cleanup(info->fb_info);
+		unregister_framebuffer(info->fb_info);
+		fb_dealloc_cmap(&info->fb_info->cmap);
+		framebuffer_release(info->fb_info);
+	}
+	free_page((unsigned long)info->page);
+	vfree(info->mfns);
+	vfree(info->fb);
+	kfree(info);
+
+	return 0;
+}
+
+static unsigned long vmalloc_to_mfn(void *address)
+{
+	return pfn_to_mfn(vmalloc_to_pfn(address));
+}
+
+static void xenfb_init_shared_page(struct xenfb_info *info,
+				   struct fb_info *fb_info)
+{
+	int i;
+	int epd = PAGE_SIZE / sizeof(info->mfns[0]);
+
+	for (i = 0; i < info->nr_pages; i++)
+		info->mfns[i] = vmalloc_to_mfn(info->fb + i * PAGE_SIZE);
+
+	for (i = 0; i * epd < info->nr_pages; i++)
+		info->page->pd[i] = vmalloc_to_mfn(&info->mfns[i * epd]);
+
+	info->page->width = fb_info->var.xres;
+	info->page->height = fb_info->var.yres;
+	info->page->depth = fb_info->var.bits_per_pixel;
+	info->page->line_length = fb_info->fix.line_length;
+	info->page->mem_length = fb_info->fix.smem_len;
+	info->page->in_cons = info->page->in_prod = 0;
+	info->page->out_cons = info->page->out_prod = 0;
+}
+
+static int xenfb_connect_backend(struct xenbus_device *dev,
+				 struct xenfb_info *info)
+{
+	int ret, evtchn, irq;
+	struct xenbus_transaction xbt;
+
+	ret = xenbus_alloc_evtchn(dev, &evtchn);
+	if (ret)
+		return ret;
+	irq = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler,
+					0, dev->devicetype, info);
+	if (irq < 0) {
+		xenbus_free_evtchn(dev, evtchn);
+		xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler");
+		return irq;
+	}
+ again:
+	ret = xenbus_transaction_start(&xbt);
+	if (ret) {
+		xenbus_dev_fatal(dev, ret, "starting transaction");
+		goto unbind_irq;
+	}
+	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_printf(xbt, dev->nodename, "protocol", "%s",
+			    XEN_IO_PROTO_ABI_NATIVE);
+	if (ret)
+		goto error_xenbus;
+	ret = xenbus_printf(xbt, dev->nodename, "feature-update", "1");
+	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");
+		goto unbind_irq;
+	}
+
+	xenbus_switch_state(dev, XenbusStateInitialised);
+	info->irq = irq;
+	return 0;
+
+ error_xenbus:
+	xenbus_transaction_end(xbt, 1);
+	xenbus_dev_fatal(dev, ret, "writing xenstore");
+ unbind_irq:
+	unbind_from_irqhandler(irq, info);
+	return ret;
+}
+
+static void xenfb_disconnect_backend(struct xenfb_info *info)
+{
+	/* Prevent xenfb refresh */
+	info->update_wanted = 0;
+	if (info->irq >= 0)
+		unbind_from_irqhandler(info->irq, info);
+	info->irq = -1;
+}
+
+static void xenfb_backend_changed(struct xenbus_device *dev,
+				  enum xenbus_state backend_state)
+{
+	struct xenfb_info *info = dev_get_drvdata(&dev->dev);
+	int val;
+
+	switch (backend_state) {
+	case XenbusStateInitialising:
+	case XenbusStateInitialised:
+	case XenbusStateReconfiguring:
+	case XenbusStateReconfigured:
+	case XenbusStateUnknown:
+	case XenbusStateClosed:
+		break;
+
+	case XenbusStateInitWait:
+InitWait:
+		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 */
+
+		if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+				 "request-update", "%d", &val) < 0)
+			val = 0;
+		if (val)
+			info->update_wanted = 1;
+
+		if (xenbus_scanf(XBT_NIL, dev->otherend,
+				 "feature-resize", "%d", &val) < 0)
+			val = 0;
+		info->feature_resize = val;
+		break;
+
+	case XenbusStateClosing:
+		xenbus_frontend_closed(dev);
+		break;
+	}
+}
+
+static const struct xenbus_device_id xenfb_ids[] = {
+	{ "vfb" },
+	{ "" }
+};
+
+static DEFINE_XENBUS_DRIVER(xenfb, ,
+	.probe = xenfb_probe,
+	.remove = xenfb_remove,
+	.resume = xenfb_resume,
+	.otherend_changed = xenfb_backend_changed,
+);
+
+static int __init xenfb_init(void)
+{
+	if (!xen_pv_domain())
+		return -ENODEV;
+
+	/* Nothing to do if running in dom0. */
+	if (xen_initial_domain())
+		return -ENODEV;
+
+	return xenbus_register_frontend(&xenfb_driver);
+}
+
+static void __exit xenfb_cleanup(void)
+{
+	xenbus_unregister_driver(&xenfb_driver);
+}
+
+module_init(xenfb_init);
+module_exit(xenfb_cleanup);
+
+MODULE_DESCRIPTION("Xen virtual framebuffer device frontend");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("xen:vfb");