Thread: [Linux-fbdev-devel] [PATCH] Add VirtIO Frame Buffer Support

SourceForge Headquarters 225 Broadway Suite 1600 San Diego, CA 92101 +1 (858) 422-6466

When we want to create a full VirtIO based machine, we're still missing
graphics output. Fortunately, Linux provides us with most of the frameworks
to render text and everything, we only need to implement a transport.

So this is a frame buffer backend written for VirtIO. Using this and my
patch to qemu, you can use paravirtualized graphics.

This is especially important on machines that can't do MMIO, as all current
graphics implementations qemu emulates I'm aware of so far fail here.

Signed-off-by: Alexander Graf <ag...@su...>
---
 drivers/video/Kconfig      |   15 +
 drivers/video/Makefile     |    1 +
 drivers/video/virtio-fb.c  |  799 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/virtio_ids.h |    1 +
 4 files changed, 816 insertions(+), 0 deletions(-)
 create mode 100644 drivers/video/virtio-fb.c

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 9bbb285..f9be4c2 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -2069,6 +2069,21 @@ config XEN_FBDEV_FRONTEND
 	  frame buffer driver.  It communicates with a back-end
 	  in another domain.
 
+config FB_VIRTIO
+	tristate "Virtio virtual frame buffer support"
+	depends on FB && VIRTIO
+	select FB_SYS_FILLRECT
+	select FB_SYS_COPYAREA
+	select FB_SYS_IMAGEBLIT
+	select FB_SYS_FOPS
+	select FB_DEFERRED_IO
+	help
+	  This driver implements a driver for a Virtio based
+	  frame buffer device.  It communicates to something that
+	  can talk Virtio too, most probably a hypervisor.
+
+	  If unsure, say N.
+
 config FB_METRONOME
 	tristate "E-Ink Metronome/8track controller support"
 	depends on FB
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 80232e1..40802c8 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -125,6 +125,7 @@ obj-$(CONFIG_FB_XILINX)           += xilinxfb.o
 obj-$(CONFIG_FB_SH_MOBILE_LCDC)	  += sh_mobile_lcdcfb.o
 obj-$(CONFIG_FB_OMAP)             += omap/
 obj-$(CONFIG_XEN_FBDEV_FRONTEND)  += xen-fbfront.o
+obj-$(CONFIG_FB_VIRTIO)           += virtio-fb.o
 obj-$(CONFIG_FB_CARMINE)          += carminefb.o
 obj-$(CONFIG_FB_MB862XX)	  += mb862xx/
 obj-$(CONFIG_FB_MSM)              += msm/
diff --git a/drivers/video/virtio-fb.c b/drivers/video/virtio-fb.c
new file mode 100644
index 0000000..2a73950
--- /dev/null
+++ b/drivers/video/virtio-fb.c
@@ -0,0 +1,799 @@
+/*
+ * VirtIO PV frame buffer device
+ *
+ * Copyright (C) 2009 Alexander Graf <ag...@su...>
+ *
+ *  Based on linux/drivers/video/virtio-fbfront.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.
+ */
+
+#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 <linux/virtio.h>
+#include <linux/virtio_ids.h>
+#include <linux/virtio_config.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+
+#define MAX_BUF			128
+
+struct virtio_fb_info {
+	struct fb_info		*fb_info;
+	unsigned char		*fb;
+	char			*inbuf;
+
+	u16			width;
+	u16			height;
+
+	int			nr_pages;
+	int			size;
+
+	struct kmem_cache	*cmd_cache;
+	struct virtqueue	*vq_in;
+	struct virtqueue	*vq_out;
+	struct virtio_device	*vdev;
+
+	void			*last_buf[MAX_BUF];
+	int			last_buf_idx;
+	spinlock_t		vfree_lock;
+	struct work_struct	vfree_work;
+	struct work_struct	refresh_work;
+};
+
+/* guest -> Host commands */
+#define VIRTIO_FB_CMD_RESIZE            0x01                                         
+#define VIRTIO_FB_CMD_FILL              0x02                                         
+#define VIRTIO_FB_CMD_BLIT              0x03                                         
+#define VIRTIO_FB_CMD_COPY              0x04                                         
+#define VIRTIO_FB_CMD_WRITE             0x05                                         
+    
+/* host -> guest commands */                                                         
+#define VIRTIO_FB_CMD_REFRESH           0x81                                         
+
+struct virtio_fb_cmd {
+	u8			cmd;
+	union {
+		struct {
+			u16	width;
+			u16	height;
+		} resize __attribute__ ((packed));
+		struct {
+			u16	x;
+			u16	y;
+			u16	width;
+			u16	height;
+		} blit __attribute__ ((packed));
+		struct {
+			u16	x1;
+			u16	y1;
+			u16	x2;
+			u16	y2;
+			u16	width;
+			u16	height;
+		} copy_area __attribute__ ((packed));
+		struct {
+			u8	rop;
+			u16	x;
+			u16	y;
+			u16	width;
+			u16	height;
+			u32	color;
+		} fill __attribute__ ((packed));
+		struct {
+			u64	offset;
+			u64	count;
+		} write __attribute__ ((packed));
+		u8		pad[23];
+	};
+
+	union {
+		/* We remember the data pointer so we we can easily free
+		   everything later by only knowing this structure */
+		char		*send_buf;
+		u64		_pad;
+	};
+} __attribute__ ((packed));
+
+enum copy_type {
+	COPY_KERNEL,
+	COPY_USER,
+	COPY_NOCOPY,
+};
+
+#define DEFAULT_WIDTH		800
+#define DEFAULT_HEIGHT		600
+#define DEFAULT_DEPTH		32
+#define DEFAULT_MEM		8
+
+#define DEFAULT_FB_LEN (DEFAULT_WIDTH * DEFAULT_HEIGHT * DEFAULT_DEPTH / 8)
+
+enum { KPARAM_MEM, KPARAM_WIDTH, KPARAM_HEIGHT, KPARAM_CNT };
+static int video[KPARAM_CNT] = { DEFAULT_MEM, DEFAULT_WIDTH, DEFAULT_HEIGHT };
+module_param_array(video, int, NULL, 0);
+MODULE_PARM_DESC(video,
+	"Video size in M,width,height in pixels (default \""
+	str(DEFAULT_MEM) ","
+	str(DEFAULT_WIDTH) ","
+	str(DEFAULT_HEIGHT) "\")");
+
+static void virtio_fb_output(struct virtqueue *vq);
+
+static void *rvmalloc(unsigned long size)
+{
+	void *mem;
+	unsigned long adr;
+
+	size = PAGE_ALIGN(size);
+	mem = vmalloc_32(size);
+	if (!mem)
+		return NULL;
+
+	memset(mem, 0, size); /* Clear the ram out, no junk to the user */
+	adr = (unsigned long) mem;
+	while (size > 0) {
+		SetPageReserved(vmalloc_to_page((void *)adr));
+		adr += PAGE_SIZE;
+		size -= PAGE_SIZE;
+	}
+
+	return mem;
+}
+
+/* This is videobuf_vmalloc_to_sg() from videobuf-dma-sg.c
+   I modified it to take an extra sg entry for the cmd and work with non
+   page-aligned pointers though */
+static struct scatterlist* vmalloc_to_sg(unsigned char *virt, int length,
+					 void *cmd, int cmd_len, int *sg_elem)
+{
+	struct scatterlist *sglist;
+	struct page *pg;
+	int nr_pages = (length+PAGE_SIZE-1)/PAGE_SIZE;
+	int sg_entries;
+	int i;
+
+	/* unaligned */
+	if ((ulong)virt & ~PAGE_MASK) {
+		int tmp_len = length - (PAGE_SIZE - ((ulong)virt & ~PAGE_MASK));
+		/* how long would it be without the first non-aligned chunk? */
+		nr_pages = (tmp_len+PAGE_SIZE-1)/PAGE_SIZE;
+		/* add the first chunk */
+		nr_pages++;
+	}
+
+	sg_entries = nr_pages + 1;
+
+	sglist = kcalloc(sg_entries, sizeof(struct scatterlist), GFP_KERNEL);
+	if (!sglist)
+		return NULL;
+	sg_init_table(sglist, sg_entries);
+
+	/* Put cmd element in */
+	sg_set_buf(&sglist[0], cmd, cmd_len);
+
+	/* Fill with elements for the data */
+	for (i = 1; i < sg_entries; i++) {
+		pg = vmalloc_to_page(virt);
+		if (!pg)
+			goto err;
+
+		if ((ulong)virt & ~PAGE_MASK) {
+			int tmp_off = ((ulong)virt & ~PAGE_MASK);
+
+			sg_set_page(&sglist[i], pg, PAGE_SIZE - tmp_off, tmp_off);
+			virt = (char*)((ulong)virt & PAGE_MASK);
+		} else {
+			sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
+		}
+		virt += PAGE_SIZE;
+	}
+
+	*sg_elem = sg_entries;
+	return sglist;
+
+ err:
+	kfree(sglist);
+	return NULL;
+}
+
+
+static void _virtio_fb_send(struct virtio_fb_info *info,
+			    struct virtio_fb_cmd *cmd,
+			    char *buf, int len, enum copy_type copy)
+{
+	char *send_buf = NULL;
+	char *sg_buf = NULL;
+	struct virtio_fb_cmd *send_cmd;
+	struct scatterlist *sg;
+	int len_cmd = sizeof(struct virtio_fb_cmd);
+	int r, sg_elem;
+
+	send_cmd = kmem_cache_alloc(info->cmd_cache, GFP_KERNEL);
+	if (!send_cmd) {
+		printk(KERN_ERR "virtio-fb: couldn't allocate cmd\n");
+		return;
+	}
+
+	memcpy(send_cmd, cmd, len_cmd);
+
+	if (len) {
+		sg_buf = send_buf = vmalloc(len);
+		if (!send_buf) {
+			printk(KERN_ERR "virtio-fb: couldn't allocate %d b\n",
+					len);
+			return;
+		}
+
+		switch (copy) {
+		case COPY_KERNEL:
+			memcpy(send_buf, buf, len);
+			break;
+		case COPY_USER:
+			r = copy_from_user(send_buf, (const __user char*)buf,
+					   len);
+			break;
+		case COPY_NOCOPY:
+			sg_buf = buf;
+			break;
+		}
+	}
+
+	send_cmd->send_buf = send_buf;
+
+	sg = vmalloc_to_sg(sg_buf, len, send_cmd, len_cmd, &sg_elem);
+	if (!sg) {
+		printk(KERN_ERR "virtio-fb: couldn't gather scatter list\n");
+		return;
+	}
+
+add_again:
+	r = info->vq_out->vq_ops->add_buf(info->vq_out, sg, sg_elem, 0, send_cmd);
+	info->vq_out->vq_ops->kick(info->vq_out);
+
+	if ( r == -ENOSPC ) {
+		/* Queue was full, so try again */
+		cpu_relax();
+		virtio_fb_output(info->vq_out);
+		goto add_again;
+	}
+
+	kfree(sg);
+}
+
+static void virtio_fb_send_user(struct virtio_fb_info *info,
+				struct virtio_fb_cmd *cmd,
+				const __user char *buf, int len)
+{
+	_virtio_fb_send(info, cmd, (char *)buf, len, COPY_USER);
+}
+
+static void virtio_fb_send_nocopy(struct virtio_fb_info *info,
+				  struct virtio_fb_cmd *cmd,
+				  char *buf, int len)
+{
+	_virtio_fb_send(info, cmd, buf, len, COPY_NOCOPY);
+}
+
+static void virtio_fb_send(struct virtio_fb_info *info, struct virtio_fb_cmd *cmd,
+			   char *buf, int len)
+{
+	_virtio_fb_send(info, cmd, buf, len, COPY_KERNEL);
+}
+
+
+static int virtio_fb_setcolreg(unsigned regno, unsigned red, unsigned green,
+			   unsigned blue, unsigned transp,
+			   struct fb_info *info)
+{
+	u32 v;
+	if (regno >= 16)
+		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) |
+	    (transp << info->var.transp.offset);
+
+	((u32 *) (info->pseudo_palette))[regno] = v;
+
+	return 0;
+}
+
+static void virtio_fb_fillrect(struct fb_info *p, const struct fb_fillrect *rect)
+{
+	struct virtio_fb_info *info = p->par;
+	struct virtio_fb_cmd cmd;
+
+	sys_fillrect(p, rect);
+
+	cmd.cmd = VIRTIO_FB_CMD_FILL;
+	cmd.fill.rop = rect->rop;
+	cmd.fill.x = rect->dx;
+	cmd.fill.y = rect->dy;
+	cmd.fill.width = rect->width;
+	cmd.fill.height = rect->height;
+	cmd.fill.color = rect->color;
+
+	virtio_fb_send(info, &cmd, NULL, 0);
+}
+
+static void virtio_fb_imageblit(struct fb_info *p, const struct fb_image *image)
+{
+	struct virtio_fb_info *info = p->par;
+	struct virtio_fb_cmd cmd;
+	char *_buf;
+	char *buf;
+	char *vfb;
+	int i, w;
+	int bpp = p->var.bits_per_pixel / 8;
+	int len = image->width * image->height * bpp;
+
+	sys_imageblit(p, image);
+
+	cmd.cmd = VIRTIO_FB_CMD_BLIT;
+	cmd.blit.x = image->dx;
+	cmd.blit.y = image->dy;
+	cmd.blit.height = image->height;
+	cmd.blit.width = image->width;
+
+	if (image->depth == 32) {
+		/* Send the image off directly */
+
+		virtio_fb_send(info, &cmd, (char*)image->data, len);
+		return;
+	}
+
+	/* Send the 32-bit translated image */
+
+	buf = _buf = vmalloc(len);
+
+	vfb = info->fb;
+	vfb += (image->dy * p->fix.line_length) + image->dx * bpp;
+
+	w = image->width * bpp;
+
+	for (i = 0; i < image->height; i++) {
+		memcpy(buf, vfb, w);
+
+		buf += w;
+		vfb += p->fix.line_length;
+	}
+
+	virtio_fb_send(info, &cmd, _buf, len);
+
+	vfree(_buf);
+}
+
+static void virtio_fb_copyarea(struct fb_info *p, const struct fb_copyarea *area)
+{
+	struct virtio_fb_info *info = p->par;
+	struct virtio_fb_cmd cmd;
+
+	sys_copyarea(p, area);
+
+	cmd.cmd = VIRTIO_FB_CMD_COPY;
+	cmd.copy_area.x1 = area->sx;
+	cmd.copy_area.y1 = area->sy;
+	cmd.copy_area.x2 = area->dx;
+	cmd.copy_area.y2 = area->dy;
+	cmd.copy_area.width = area->width;
+	cmd.copy_area.height = area->height;
+
+	virtio_fb_send(info, &cmd, NULL, 0);
+}
+
+static ssize_t virtio_fb_write(struct fb_info *p, const char __user *buf,
+			size_t count, loff_t *ppos)
+{
+	struct virtio_fb_info *info = p->par;
+	struct virtio_fb_cmd cmd;
+	loff_t pos = *ppos;
+	ssize_t res;
+
+	res = fb_sys_write(p, buf, count, ppos);
+
+	cmd.cmd = VIRTIO_FB_CMD_WRITE;
+	cmd.write.offset = pos;
+	cmd.write.count = count;
+
+	virtio_fb_send_user(info, &cmd, buf, count);
+	return res;
+}
+
+static int
+virtio_fb_check_var(struct fb_var_screeninfo *var, struct fb_info *p)
+{
+	struct virtio_fb_info *info = p->par;
+
+	if (var->bits_per_pixel != DEFAULT_DEPTH) {
+		/* We only support 32 bpp */
+		return -EINVAL;
+	}
+
+	if ((var->xres * var->yres * DEFAULT_DEPTH / 8) > info->size) {
+		/* Doesn't fit in the frame buffer */
+		return -EINVAL;
+	}
+
+	var->xres_virtual = var->xres;
+	var->yres_virtual = var->yres;
+
+	return 0;
+}
+
+static int virtio_fb_set_par(struct fb_info *p)
+{
+	struct virtio_fb_info *info = p->par;
+	struct virtio_fb_cmd cmd;
+
+	/* Do nothing if we're on that resolution already */
+	if ((p->var.xres == info->width) &&
+	    (p->var.yres == info->height))
+		return 0;
+
+	info->width = p->var.xres;
+	info->height = p->var.yres;
+	p->fix.line_length = p->var.xres_virtual * 4;
+
+	/* Notify hypervisor */
+
+	cmd.cmd = VIRTIO_FB_CMD_RESIZE;
+	cmd.resize.width = p->var.xres;
+	cmd.resize.height = p->var.yres;
+
+	virtio_fb_send(info, &cmd, NULL, 0);
+
+	return 0;
+}
+
+static struct fb_ops virtio_fb_ops = {
+	.owner		= THIS_MODULE,
+	.fb_read	= fb_sys_read,
+	.fb_write	= virtio_fb_write,
+	.fb_setcolreg	= virtio_fb_setcolreg,
+	.fb_fillrect	= virtio_fb_fillrect,
+	.fb_copyarea	= virtio_fb_copyarea,
+	.fb_imageblit	= virtio_fb_imageblit,
+	.fb_check_var	= virtio_fb_check_var,
+	.fb_set_par     = virtio_fb_set_par,
+};
+
+static __devinit void
+virtio_fb_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 void virtio_fb_deferred_io(struct fb_info *fb_info,
+				  struct list_head *pagelist)
+{
+	struct virtio_fb_info *info = fb_info->par;
+	struct page *page;
+	unsigned long beg, end;
+	int y1, y2, miny, maxy;
+	struct virtio_fb_cmd cmd;
+
+	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;
+	}
+
+	if (miny != INT_MAX) {
+		cmd.cmd = VIRTIO_FB_CMD_WRITE;
+		cmd.write.offset = miny * fb_info->fix.line_length;
+		cmd.write.count = (maxy - miny + 1) * fb_info->fix.line_length;
+
+		virtio_fb_send_nocopy(info, &cmd, info->fb + cmd.write.offset,
+				      cmd.write.count);
+	}
+}
+
+static struct fb_deferred_io virtio_fb_defio = {
+	.delay		= HZ / 20,
+	.deferred_io	= virtio_fb_deferred_io,
+};
+
+/* Callback when the host kicks our input queue.
+ *
+ * This is to enable notifications from host to guest. */
+static void virtio_fb_input(struct virtqueue *vq)
+{
+	struct virtio_fb_info *info = dev_get_drvdata(&vq->vdev->dev);
+	int len, i;
+	void *x;
+	void *reinject[3];
+	int reinject_count = 0;
+
+	while ((x = vq->vq_ops->get_buf(vq, &len)) != NULL) {
+		struct virtio_fb_cmd *cmd = x;
+
+		/* Make sure we're getting an inbuf page! */
+		BUG_ON((x != info->inbuf) &&
+		       (x != (info->inbuf + PAGE_SIZE)) &&
+		       (x != (info->inbuf + (PAGE_SIZE * 2))));
+
+		switch (cmd->cmd) {
+		case VIRTIO_FB_CMD_REFRESH:
+			schedule_work(&info->refresh_work);
+			break;
+		}
+
+		reinject[reinject_count++] = x;
+	}
+
+
+	for (i = 0; i < reinject_count; i++) {
+		struct scatterlist sg;
+		void *x = reinject[i];
+
+		sg_init_one(&sg, x, PAGE_SIZE);
+		vq->vq_ops->add_buf(vq, &sg, 0, 1, x);
+		vq->vq_ops->kick(vq);
+	}
+}
+
+/* Asynchronous snippet to send all screen contents to the host */
+static void deferred_refresh(struct work_struct *work)
+{
+	struct virtio_fb_info *info = container_of(work, struct virtio_fb_info,
+						   refresh_work);
+	struct virtio_fb_cmd cmd;
+
+	cmd.cmd = VIRTIO_FB_CMD_WRITE;
+	cmd.write.offset = 0;
+	cmd.write.count = info->width * info->height * 4;
+
+	virtio_fb_send_nocopy(info, &cmd, info->fb, cmd.write.count);
+}
+
+/* Asynchronous garbage collector :-) */
+static void deferred_vfree(struct work_struct *work)
+{
+	struct virtio_fb_info *info = container_of(work, struct virtio_fb_info,
+						   vfree_work);
+	int i;
+	unsigned long flags;
+	void *last_buf[MAX_BUF];
+	int idx;
+
+	spin_lock_irqsave(&info->vfree_lock, flags);
+
+	idx = info->last_buf_idx;
+	memcpy(last_buf, info->last_buf, sizeof(void*) * MAX_BUF);
+	info->last_buf_idx = 0;
+
+	spin_unlock_irqrestore(&info->vfree_lock, flags);
+
+	for (i = 0; i < idx; i++) {
+		vfree(last_buf[i]);
+	}
+}
+
+/* Callback when the host kicks our output queue. This can only mean it's done
+ * processing an item, so let's free up the memory occupied by the entries */
+static void virtio_fb_output(struct virtqueue *vq)
+{
+	struct virtio_fb_info *info = dev_get_drvdata(&vq->vdev->dev);
+	int len;
+	void *x;
+
+	while ((x = vq->vq_ops->get_buf(vq, &len)) != NULL) {
+		struct virtio_fb_cmd *cmd = x;
+
+		if (cmd->send_buf) {
+			spin_lock(&info->vfree_lock);
+			if (info->last_buf_idx != MAX_BUF) {
+				info->last_buf[info->last_buf_idx++] =
+					cmd->send_buf;
+			}
+			spin_unlock(&info->vfree_lock);
+
+			schedule_work(&info->vfree_work);
+		}
+
+		kmem_cache_free(info->cmd_cache, x);
+	}
+}
+
+static int __devinit virtio_fb_probe(struct virtio_device *dev)
+{
+	vq_callback_t *callbacks[] = { virtio_fb_input, virtio_fb_output };
+	const char *names[] = { "input", "output" };
+	struct virtio_fb_info *info;
+	struct virtqueue *vqs[2];
+	struct fb_info *fb_info = NULL;
+	int fb_size, res_size;
+	int ret, err, i;
+	char *inbuf;
+
+	err = dev->config->find_vqs(dev, 2, vqs, callbacks, names);
+	if (err) {
+		printk(KERN_ERR "VirtIO FB: couldn't find VQs\n");
+		return err;
+	}
+
+	info = kmalloc(sizeof(*info), GFP_KERNEL);
+	if (info == NULL)
+		return -ENOMEM;
+
+	info->vq_in = vqs[0];
+	info->vq_out = vqs[1];
+
+	res_size = video[KPARAM_WIDTH] * video[KPARAM_HEIGHT] * DEFAULT_DEPTH / 8;
+	fb_size = video[KPARAM_MEM] * 1024 * 1024;
+
+	if (res_size > fb_size) {
+		video[KPARAM_WIDTH] = DEFAULT_WIDTH;
+		video[KPARAM_HEIGHT] = DEFAULT_HEIGHT;
+	}
+
+	dev_set_drvdata(&dev->dev, info);
+	info->vdev = dev;
+
+	info->fb = rvmalloc(fb_size);
+	if (info->fb == NULL)
+		goto error_nomem;
+
+	info->nr_pages = (fb_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	info->size = fb_size;
+
+	fb_info = framebuffer_alloc(sizeof(u32) * 256, NULL);
+	if (fb_info == NULL)
+		goto error_nomem;
+
+	inbuf = kmalloc(PAGE_SIZE * 3, GFP_KERNEL);
+	info->inbuf = inbuf;
+	for (i = 0; i < (3 * PAGE_SIZE); i += PAGE_SIZE) {
+		struct scatterlist sg;
+
+		sg_init_one(&sg, inbuf + i, PAGE_SIZE);
+		info->vq_in->vq_ops->add_buf(info->vq_in, &sg, 0, 1, inbuf + i);
+	}
+	info->vq_in->vq_ops->kick(info->vq_in);
+
+	fb_info->pseudo_palette = fb_info->par;
+	fb_info->par = info;
+
+	fb_info->screen_base = info->fb;
+
+	fb_info->fbops = &virtio_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 = DEFAULT_DEPTH;
+
+	fb_info->var.transp = (struct fb_bitfield){24, 8, 0};
+	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 * DEFAULT_DEPTH / 8;
+	fb_info->fix.smem_start = 0;
+	fb_info->fix.smem_len = fb_size;
+	strcpy(fb_info->fix.id, "virtio_fb");
+	fb_info->fix.type = FB_TYPE_PACKED_PIXELS;
+	fb_info->fix.accel = FB_ACCEL_NONE;
+
+	fb_info->flags = FBINFO_FLAG_DEFAULT | FBINFO_HWACCEL_COPYAREA |
+			 FBINFO_READS_FAST;
+
+	ret = fb_alloc_cmap(&fb_info->cmap, 256, 0);
+	if (ret < 0) {
+		framebuffer_release(fb_info);
+		goto error;
+	}
+
+	info->cmd_cache = kmem_cache_create("virtio_fb_cmd",
+					    sizeof(struct virtio_fb_cmd),
+					    0, 0, NULL);
+
+	if (!info->cmd_cache) {
+		framebuffer_release(fb_info);
+		goto error;
+	}
+
+	fb_info->fbdefio = &virtio_fb_defio;
+	fb_deferred_io_init(fb_info);
+
+	INIT_WORK(&info->refresh_work, deferred_refresh);
+	INIT_WORK(&info->vfree_work, deferred_vfree);
+	spin_lock_init(&info->vfree_lock);
+
+	ret = register_framebuffer(fb_info);
+	if (ret) {
+		fb_deferred_io_cleanup(fb_info);
+		fb_dealloc_cmap(&fb_info->cmap);
+		framebuffer_release(fb_info);
+		goto error;
+	}
+	info->fb_info = fb_info;
+
+	virtio_fb_make_preferred_console();
+	return 0;
+
+ error_nomem:
+	ret = -ENOMEM;
+ error:
+	framebuffer_release(fb_info);
+	return ret;
+}
+
+static void virtio_fb_apply_config(struct virtio_device *dev)
+{
+}
+
+static struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_FB, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+
+static unsigned int features[] = {
+};
+
+static struct virtio_driver virtio_console = {
+	.feature_table = features,
+	.feature_table_size = ARRAY_SIZE(features),
+	.driver.name =  KBUILD_MODNAME,
+	.driver.owner = THIS_MODULE,
+	.id_table =     id_table,
+	.probe =        virtio_fb_probe,
+	.config_changed = virtio_fb_apply_config,
+};
+
+static int __init init(void)
+{
+	return register_virtio_driver(&virtio_console);
+}
+module_init(init);
+
+
+MODULE_DEVICE_TABLE(virtio, id_table);
+MODULE_DESCRIPTION("Virtio framebuffer driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/virtio_ids.h b/include/linux/virtio_ids.h
index 06660c0..72e39f7 100644
--- a/include/linux/virtio_ids.h
+++ b/include/linux/virtio_ids.h
@@ -12,6 +12,7 @@
 #define VIRTIO_ID_CONSOLE	3 /* virtio console */
 #define VIRTIO_ID_RNG		4 /* virtio ring */
 #define VIRTIO_ID_BALLOON	5 /* virtio balloon */
+#define VIRTIO_ID_FB		6 /* virtio framebuffer */
 #define VIRTIO_ID_9P		9 /* 9p virtio console */
 
 #endif /* _LINUX_VIRTIO_IDS_H */
-- 
1.6.0.2





Thread: [Linux-fbdev-devel] [PATCH] Add VirtIO Frame Buffer Support

linux-fbdev-devel