drivers/video/xen-fbfront.c - kernel/msm-4.9 - Gitiles

 /*
  * 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/vmalloc.h>
 #include <linux/mm.h>
 #include <asm/xen/hypervisor.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;

 	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 = vmalloc(fb_size);
 	if (info->fb == NULL)
 		goto error_nomem;
 	memset(info->fb, 0, fb_size);

 	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;

 	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 = register_framebuffer(fb_info);
 	if (ret) {
 		fb_deferred_io_cleanup(fb_info);
 		fb_dealloc_cmap(&fb_info->cmap);
 		framebuffer_release(fb_info);
 		xenbus_dev_fatal(dev, ret, "register_framebuffer");
 		goto error;
 	}
 	info->fb_info = fb_info;

 	ret = xenfb_connect_backend(dev, info);
 	if (ret < 0)
 		goto error;

 	xenfb_make_preferred_console();
 	return 0;

  error_nomem:
 	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;

 	acquire_console_sem();
 	for (c = console_drivers; c; c = c->next) {
 		if (!strcmp(c->name, "tty") && c->index == 0)
 			break;
 	}
 	release_console_sem();
 	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;
 	struct xenbus_transaction xbt;

 	ret = xenbus_alloc_evtchn(dev, &evtchn);
 	if (ret)
 		return ret;
 	ret = bind_evtchn_to_irqhandler(evtchn, xenfb_event_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_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");
 		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 xenfb_disconnect_backend(struct xenfb_info *info)
 {
 	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 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 struct xenbus_device_id xenfb_ids[] = {
 	{ "vfb" },
 	{ "" }
 };

 static struct xenbus_driver xenfb_driver = {
 	.name = "vfb",
 	.owner = THIS_MODULE,
 	.ids = xenfb_ids,
 	.probe = xenfb_probe,
 	.remove = xenfb_remove,
 	.resume = xenfb_resume,
 	.otherend_changed = xenfb_backend_changed,
 };

 static int __init xenfb_init(void)
 {
 	if (!xen_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");
	/*
	* 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/vmalloc.h>
	#include <linux/mm.h>
	#include <asm/xen/hypervisor.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;

	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 = vmalloc(fb_size);
	if (info->fb == NULL)
	goto error_nomem;
	memset(info->fb, 0, fb_size);

	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;

	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 = register_framebuffer(fb_info);
	if (ret) {
	fb_deferred_io_cleanup(fb_info);
	fb_dealloc_cmap(&fb_info->cmap);
	framebuffer_release(fb_info);
	xenbus_dev_fatal(dev, ret, "register_framebuffer");
	goto error;
	}
	info->fb_info = fb_info;

	ret = xenfb_connect_backend(dev, info);
	if (ret < 0)
	goto error;

	xenfb_make_preferred_console();
	return 0;

	error_nomem:
	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;

	acquire_console_sem();
	for (c = console_drivers; c; c = c->next) {
	if (!strcmp(c->name, "tty") && c->index == 0)
	break;
	}
	release_console_sem();
	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;
	struct xenbus_transaction xbt;

	ret = xenbus_alloc_evtchn(dev, &evtchn);
	if (ret)
	return ret;
	ret = bind_evtchn_to_irqhandler(evtchn, xenfb_event_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_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");
	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 xenfb_disconnect_backend(struct xenfb_info *info)
	{
	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 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 struct xenbus_device_id xenfb_ids[] = {
	{ "vfb" },
	{ "" }
	};

	static struct xenbus_driver xenfb_driver = {
	.name = "vfb",
	.owner = THIS_MODULE,
	.ids = xenfb_ids,
	.probe = xenfb_probe,
	.remove = xenfb_remove,
	.resume = xenfb_resume,
	.otherend_changed = xenfb_backend_changed,
	};

	static int __init xenfb_init(void)
	{
	if (!xen_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");