/*
   * Copyright (c) 2012, Microsoft Corporation.
   *
   * Author:
   *   Haiyang Zhang <haiyangz@microsoft.com>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published
   * by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
   * NON INFRINGEMENT.  See the GNU General Public License for more
   * details.
   */
  
  /*
   * Hyper-V Synthetic Video Frame Buffer Driver
   *
   * This is the driver for the Hyper-V Synthetic Video, which supports
   * screen resolution up to Full HD 1920x1080 with 32 bit color on Windows
   * Server 2012, and 1600x1200 with 16 bit color on Windows Server 2008 R2
   * or earlier.
   *
   * It also solves the double mouse cursor issue of the emulated video mode.
   *
   * The default screen resolution is 1152x864, which may be changed by a
   * kernel parameter:
   *     video=hyperv_fb:<width>x<height>
   *     For example: video=hyperv_fb:1280x1024
   *
   * Portrait orientation is also supported:
   *     For example: video=hyperv_fb:864x1152
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/completion.h>
  #include <linux/fb.h>
  #include <linux/pci.h>
  
  #include <linux/hyperv.h>
  
  
  /* Hyper-V Synthetic Video Protocol definitions and structures */
  #define MAX_VMBUS_PKT_SIZE 0x4000
  
  #define SYNTHVID_VERSION(major, minor) ((minor) << 16 | (major))
  #define SYNTHVID_VERSION_WIN7 SYNTHVID_VERSION(3, 0)
  #define SYNTHVID_VERSION_WIN8 SYNTHVID_VERSION(3, 2)
  
  #define SYNTHVID_DEPTH_WIN7 16
  #define SYNTHVID_DEPTH_WIN8 32
  
  #define SYNTHVID_FB_SIZE_WIN7 (4 * 1024 * 1024)
  #define SYNTHVID_WIDTH_MAX_WIN7 1600
  #define SYNTHVID_HEIGHT_MAX_WIN7 1200
  
  #define SYNTHVID_FB_SIZE_WIN8 (8 * 1024 * 1024)
  
  #define PCI_VENDOR_ID_MICROSOFT 0x1414
  #define PCI_DEVICE_ID_HYPERV_VIDEO 0x5353
  
  
  enum pipe_msg_type {
  	PIPE_MSG_INVALID,
  	PIPE_MSG_DATA,
  	PIPE_MSG_MAX
  };
  
  struct pipe_msg_hdr {
  	u32 type;
  	u32 size; /* size of message after this field */
  } __packed;
  
  
  enum synthvid_msg_type {
  	SYNTHVID_ERROR			= 0,
  	SYNTHVID_VERSION_REQUEST	= 1,
  	SYNTHVID_VERSION_RESPONSE	= 2,
  	SYNTHVID_VRAM_LOCATION		= 3,
  	SYNTHVID_VRAM_LOCATION_ACK	= 4,
  	SYNTHVID_SITUATION_UPDATE	= 5,
  	SYNTHVID_SITUATION_UPDATE_ACK	= 6,
  	SYNTHVID_POINTER_POSITION	= 7,
  	SYNTHVID_POINTER_SHAPE		= 8,
  	SYNTHVID_FEATURE_CHANGE		= 9,
  	SYNTHVID_DIRT			= 10,
  
  	SYNTHVID_MAX			= 11
  };
  
  struct synthvid_msg_hdr {
  	u32 type;
  	u32 size;  /* size of this header + payload after this field*/
  } __packed;
  
  
  struct synthvid_version_req {
  	u32 version;
  } __packed;
  
  struct synthvid_version_resp {
  	u32 version;
  	u8 is_accepted;
  	u8 max_video_outputs;
  } __packed;
  
  struct synthvid_vram_location {
  	u64 user_ctx;
  	u8 is_vram_gpa_specified;
  	u64 vram_gpa;
  } __packed;
  
  struct synthvid_vram_location_ack {
  	u64 user_ctx;
  } __packed;
  
  struct video_output_situation {
  	u8 active;
  	u32 vram_offset;
  	u8 depth_bits;
  	u32 width_pixels;
  	u32 height_pixels;
  	u32 pitch_bytes;
  } __packed;
  
  struct synthvid_situation_update {
  	u64 user_ctx;
  	u8 video_output_count;
  	struct video_output_situation video_output[1];
  } __packed;
  
  struct synthvid_situation_update_ack {
  	u64 user_ctx;
  } __packed;
  
  struct synthvid_pointer_position {
  	u8 is_visible;
  	u8 video_output;
  	s32 image_x;
  	s32 image_y;
  } __packed;
  
  
  #define CURSOR_MAX_X 96
  #define CURSOR_MAX_Y 96
  #define CURSOR_ARGB_PIXEL_SIZE 4
  #define CURSOR_MAX_SIZE (CURSOR_MAX_X * CURSOR_MAX_Y * CURSOR_ARGB_PIXEL_SIZE)
  #define CURSOR_COMPLETE (-1)
  
  struct synthvid_pointer_shape {
  	u8 part_idx;
  	u8 is_argb;
  	u32 width; /* CURSOR_MAX_X at most */
  	u32 height; /* CURSOR_MAX_Y at most */
  	u32 hot_x; /* hotspot relative to upper-left of pointer image */
  	u32 hot_y;
  	u8 data[4];
  } __packed;
  
  struct synthvid_feature_change {
  	u8 is_dirt_needed;
  	u8 is_ptr_pos_needed;
  	u8 is_ptr_shape_needed;
  	u8 is_situ_needed;
  } __packed;
  
  struct rect {
  	s32 x1, y1; /* top left corner */
  	s32 x2, y2; /* bottom right corner, exclusive */
  } __packed;
  
  struct synthvid_dirt {
  	u8 video_output;
  	u8 dirt_count;
  	struct rect rect[1];
  } __packed;
  
  struct synthvid_msg {
  	struct pipe_msg_hdr pipe_hdr;
  	struct synthvid_msg_hdr vid_hdr;
  	union {
  		struct synthvid_version_req ver_req;
  		struct synthvid_version_resp ver_resp;
  		struct synthvid_vram_location vram;
  		struct synthvid_vram_location_ack vram_ack;
  		struct synthvid_situation_update situ;
  		struct synthvid_situation_update_ack situ_ack;
  		struct synthvid_pointer_position ptr_pos;
  		struct synthvid_pointer_shape ptr_shape;
  		struct synthvid_feature_change feature_chg;
  		struct synthvid_dirt dirt;
  	};
  } __packed;
  
  
  
  /* FB driver definitions and structures */
  #define HVFB_WIDTH 1152 /* default screen width */
  #define HVFB_HEIGHT 864 /* default screen height */
  #define HVFB_WIDTH_MIN 640
  #define HVFB_HEIGHT_MIN 480
  
  #define RING_BUFSIZE (256 * 1024)
  #define VSP_TIMEOUT (10 * HZ)
  #define HVFB_UPDATE_DELAY (HZ / 20)
  
  struct hvfb_par {
  	struct fb_info *info;
  	bool fb_ready; /* fb device is ready */
  	struct completion wait;
  	u32 synthvid_version;
  
  	struct delayed_work dwork;
  	bool update;
  
  	u32 pseudo_palette[16];
  	u8 init_buf[MAX_VMBUS_PKT_SIZE];
  	u8 recv_buf[MAX_VMBUS_PKT_SIZE];
  };
  
  static uint screen_width = HVFB_WIDTH;
  static uint screen_height = HVFB_HEIGHT;
  static uint screen_depth;
  static uint screen_fb_size;
  
  /* Send message to Hyper-V host */
  static inline int synthvid_send(struct hv_device *hdev,
  				struct synthvid_msg *msg)
  {
  	static atomic64_t request_id = ATOMIC64_INIT(0);
  	int ret;
  
  	msg->pipe_hdr.type = PIPE_MSG_DATA;
  	msg->pipe_hdr.size = msg->vid_hdr.size;
  
  	ret = vmbus_sendpacket(hdev->channel, msg,
  			       msg->vid_hdr.size + sizeof(struct pipe_msg_hdr),
  			       atomic64_inc_return(&request_id),
  			       VM_PKT_DATA_INBAND, 0);
  
  	if (ret)
  		pr_err("Unable to send packet via vmbus
  ");
  
  	return ret;
  }
  
  
  /* Send screen resolution info to host */
  static int synthvid_send_situ(struct hv_device *hdev)
  {
  	struct fb_info *info = hv_get_drvdata(hdev);
  	struct synthvid_msg msg;
  
  	if (!info)
  		return -ENODEV;
  
  	memset(&msg, 0, sizeof(struct synthvid_msg));
  
  	msg.vid_hdr.type = SYNTHVID_SITUATION_UPDATE;
  	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
  		sizeof(struct synthvid_situation_update);
  	msg.situ.user_ctx = 0;
  	msg.situ.video_output_count = 1;
  	msg.situ.video_output[0].active = 1;
  	msg.situ.video_output[0].vram_offset = 0;
  	msg.situ.video_output[0].depth_bits = info->var.bits_per_pixel;
  	msg.situ.video_output[0].width_pixels = info->var.xres;
  	msg.situ.video_output[0].height_pixels = info->var.yres;
  	msg.situ.video_output[0].pitch_bytes = info->fix.line_length;
  
  	synthvid_send(hdev, &msg);
  
  	return 0;
  }
  
  /* Send mouse pointer info to host */
  static int synthvid_send_ptr(struct hv_device *hdev)
  {
  	struct synthvid_msg msg;
  
  	memset(&msg, 0, sizeof(struct synthvid_msg));
  	msg.vid_hdr.type = SYNTHVID_POINTER_POSITION;
  	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
  		sizeof(struct synthvid_pointer_position);
  	msg.ptr_pos.is_visible = 1;
  	msg.ptr_pos.video_output = 0;
  	msg.ptr_pos.image_x = 0;
  	msg.ptr_pos.image_y = 0;
  	synthvid_send(hdev, &msg);
  
  	memset(&msg, 0, sizeof(struct synthvid_msg));
  	msg.vid_hdr.type = SYNTHVID_POINTER_SHAPE;
  	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
  		sizeof(struct synthvid_pointer_shape);
  	msg.ptr_shape.part_idx = CURSOR_COMPLETE;
  	msg.ptr_shape.is_argb = 1;
  	msg.ptr_shape.width = 1;
  	msg.ptr_shape.height = 1;
  	msg.ptr_shape.hot_x = 0;
  	msg.ptr_shape.hot_y = 0;
  	msg.ptr_shape.data[0] = 0;
  	msg.ptr_shape.data[1] = 1;
  	msg.ptr_shape.data[2] = 1;
  	msg.ptr_shape.data[3] = 1;
  	synthvid_send(hdev, &msg);
  
  	return 0;
  }
  
  /* Send updated screen area (dirty rectangle) location to host */
  static int synthvid_update(struct fb_info *info)
  {
  	struct hv_device *hdev = device_to_hv_device(info->device);
  	struct synthvid_msg msg;
  
  	memset(&msg, 0, sizeof(struct synthvid_msg));
  
  	msg.vid_hdr.type = SYNTHVID_DIRT;
  	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
  		sizeof(struct synthvid_dirt);
  	msg.dirt.video_output = 0;
  	msg.dirt.dirt_count = 1;
  	msg.dirt.rect[0].x1 = 0;
  	msg.dirt.rect[0].y1 = 0;
  	msg.dirt.rect[0].x2 = info->var.xres;
  	msg.dirt.rect[0].y2 = info->var.yres;
  
  	synthvid_send(hdev, &msg);
  
  	return 0;
  }
  
  
  /*
   * Actions on received messages from host:
   * Complete the wait event.
   * Or, reply with screen and cursor info.
   */
  static void synthvid_recv_sub(struct hv_device *hdev)
  {
  	struct fb_info *info = hv_get_drvdata(hdev);
  	struct hvfb_par *par;
  	struct synthvid_msg *msg;
  
  	if (!info)
  		return;
  
  	par = info->par;
  	msg = (struct synthvid_msg *)par->recv_buf;
  
  	/* Complete the wait event */
  	if (msg->vid_hdr.type == SYNTHVID_VERSION_RESPONSE ||
  	    msg->vid_hdr.type == SYNTHVID_VRAM_LOCATION_ACK) {
  		memcpy(par->init_buf, msg, MAX_VMBUS_PKT_SIZE);
  		complete(&par->wait);
  		return;
  	}
  
  	/* Reply with screen and cursor info */
  	if (msg->vid_hdr.type == SYNTHVID_FEATURE_CHANGE) {
  		if (par->fb_ready) {
  			synthvid_send_ptr(hdev);
  			synthvid_send_situ(hdev);
  		}
  
  		par->update = msg->feature_chg.is_dirt_needed;
  		if (par->update)
  			schedule_delayed_work(&par->dwork, HVFB_UPDATE_DELAY);
  	}
  }
  
  /* Receive callback for messages from the host */
  static void synthvid_receive(void *ctx)
  {
  	struct hv_device *hdev = ctx;
  	struct fb_info *info = hv_get_drvdata(hdev);
  	struct hvfb_par *par;
  	struct synthvid_msg *recv_buf;
  	u32 bytes_recvd;
  	u64 req_id;
  	int ret;
  
  	if (!info)
  		return;
  
  	par = info->par;
  	recv_buf = (struct synthvid_msg *)par->recv_buf;
  
  	do {
  		ret = vmbus_recvpacket(hdev->channel, recv_buf,
  				       MAX_VMBUS_PKT_SIZE,
  				       &bytes_recvd, &req_id);
  		if (bytes_recvd > 0 &&
  		    recv_buf->pipe_hdr.type == PIPE_MSG_DATA)
  			synthvid_recv_sub(hdev);
  	} while (bytes_recvd > 0 && ret == 0);
  }
  
  /* Check synthetic video protocol version with the host */
  static int synthvid_negotiate_ver(struct hv_device *hdev, u32 ver)
  {
  	struct fb_info *info = hv_get_drvdata(hdev);
  	struct hvfb_par *par = info->par;
  	struct synthvid_msg *msg = (struct synthvid_msg *)par->init_buf;
  	int t, ret = 0;
  
  	memset(msg, 0, sizeof(struct synthvid_msg));
  	msg->vid_hdr.type = SYNTHVID_VERSION_REQUEST;
  	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
  		sizeof(struct synthvid_version_req);
  	msg->ver_req.version = ver;
  	synthvid_send(hdev, msg);
  
  	t = wait_for_completion_timeout(&par->wait, VSP_TIMEOUT);
  	if (!t) {
  		pr_err("Time out on waiting version response
  ");
  		ret = -ETIMEDOUT;
  		goto out;
  	}
  	if (!msg->ver_resp.is_accepted) {
  		ret = -ENODEV;
  		goto out;
  	}
  
  	par->synthvid_version = ver;
  
  out:
  	return ret;
  }
  
  /* Connect to VSP (Virtual Service Provider) on host */
  static int synthvid_connect_vsp(struct hv_device *hdev)
  {
  	struct fb_info *info = hv_get_drvdata(hdev);
  	struct hvfb_par *par = info->par;
  	int ret;
  
  	ret = vmbus_open(hdev->channel, RING_BUFSIZE, RING_BUFSIZE,
  			 NULL, 0, synthvid_receive, hdev);
  	if (ret) {
  		pr_err("Unable to open vmbus channel
  ");
  		return ret;
  	}
  
  	/* Negotiate the protocol version with host */
  	if (vmbus_proto_version == VERSION_WS2008 ||
  	    vmbus_proto_version == VERSION_WIN7)
  		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN7);
  	else
  		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN8);
  
  	if (ret) {
  		pr_err("Synthetic video device version not accepted
  ");
  		goto error;
  	}
  
  	if (par->synthvid_version == SYNTHVID_VERSION_WIN7) {
  		screen_depth = SYNTHVID_DEPTH_WIN7;
  		screen_fb_size = SYNTHVID_FB_SIZE_WIN7;
  	} else {
  		screen_depth = SYNTHVID_DEPTH_WIN8;
  		screen_fb_size = SYNTHVID_FB_SIZE_WIN8;
  	}
  
  	return 0;
  
  error:
  	vmbus_close(hdev->channel);
  	return ret;
  }
  
  /* Send VRAM and Situation messages to the host */
  static int synthvid_send_config(struct hv_device *hdev)
  {
  	struct fb_info *info = hv_get_drvdata(hdev);
  	struct hvfb_par *par = info->par;
  	struct synthvid_msg *msg = (struct synthvid_msg *)par->init_buf;
  	int t, ret = 0;
  
  	/* Send VRAM location */
  	memset(msg, 0, sizeof(struct synthvid_msg));
  	msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION;
  	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
  		sizeof(struct synthvid_vram_location);
  	msg->vram.user_ctx = msg->vram.vram_gpa = info->fix.smem_start;
  	msg->vram.is_vram_gpa_specified = 1;
  	synthvid_send(hdev, msg);
  
  	t = wait_for_completion_timeout(&par->wait, VSP_TIMEOUT);
  	if (!t) {
  		pr_err("Time out on waiting vram location ack
  ");
  		ret = -ETIMEDOUT;
  		goto out;
  	}
  	if (msg->vram_ack.user_ctx != info->fix.smem_start) {
  		pr_err("Unable to set VRAM location
  ");
  		ret = -ENODEV;
  		goto out;
  	}
  
  	/* Send pointer and situation update */
  	synthvid_send_ptr(hdev);
  	synthvid_send_situ(hdev);
  
  out:
  	return ret;
  }
  
  
  /*
   * Delayed work callback:
   * It is called at HVFB_UPDATE_DELAY or longer time interval to process
   * screen updates. It is re-scheduled if further update is necessary.
   */
  static void hvfb_update_work(struct work_struct *w)
  {
  	struct hvfb_par *par = container_of(w, struct hvfb_par, dwork.work);
  	struct fb_info *info = par->info;
  
  	if (par->fb_ready)
  		synthvid_update(info);
  
  	if (par->update)
  		schedule_delayed_work(&par->dwork, HVFB_UPDATE_DELAY);
  }
  
  
  /* Framebuffer operation handlers */
  
  static int hvfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
  {
  	if (var->xres < HVFB_WIDTH_MIN || var->yres < HVFB_HEIGHT_MIN ||
  	    var->xres > screen_width || var->yres >  screen_height ||
  	    var->bits_per_pixel != screen_depth)
  		return -EINVAL;
  
  	var->xres_virtual = var->xres;
  	var->yres_virtual = var->yres;
  
  	return 0;
  }
  
  static int hvfb_set_par(struct fb_info *info)
  {
  	struct hv_device *hdev = device_to_hv_device(info->device);
  
  	return synthvid_send_situ(hdev);
  }
  
  
  static inline u32 chan_to_field(u32 chan, struct fb_bitfield *bf)
  {
  	return ((chan & 0xffff) >> (16 - bf->length)) << bf->offset;
  }
  
  static int hvfb_setcolreg(unsigned regno, unsigned red, unsigned green,
  			  unsigned blue, unsigned transp, struct fb_info *info)
  {
  	u32 *pal = info->pseudo_palette;
  
  	if (regno > 15)
  		return -EINVAL;
  
  	pal[regno] = chan_to_field(red, &info->var.red)
  		| chan_to_field(green, &info->var.green)
  		| chan_to_field(blue, &info->var.blue)
  		| chan_to_field(transp, &info->var.transp);
  
  	return 0;
  }
  
  static int hvfb_blank(int blank, struct fb_info *info)
  {
  	return 1;	/* get fb_blank to set the colormap to all black */
  }
  
  static struct fb_ops hvfb_ops = {
  	.owner = THIS_MODULE,
  	.fb_check_var = hvfb_check_var,
  	.fb_set_par = hvfb_set_par,
  	.fb_setcolreg = hvfb_setcolreg,
  	.fb_fillrect = cfb_fillrect,
  	.fb_copyarea = cfb_copyarea,
  	.fb_imageblit = cfb_imageblit,
  	.fb_blank = hvfb_blank,
  };
  
  
  /* Get options from kernel paramenter "video=" */
  static void hvfb_get_option(struct fb_info *info)
  {
  	struct hvfb_par *par = info->par;
  	char *opt = NULL, *p;
  	uint x = 0, y = 0;
  
  	if (fb_get_options(KBUILD_MODNAME, &opt) || !opt || !*opt)
  		return;
  
  	p = strsep(&opt, "x");
  	if (!*p || kstrtouint(p, 0, &x) ||
  	    !opt || !*opt || kstrtouint(opt, 0, &y)) {
  		pr_err("Screen option is invalid: skipped
  ");
  		return;
  	}
  
  	if (x < HVFB_WIDTH_MIN || y < HVFB_HEIGHT_MIN ||
  	    (par->synthvid_version == SYNTHVID_VERSION_WIN8 &&
  	     x * y * screen_depth / 8 > SYNTHVID_FB_SIZE_WIN8) ||
  	    (par->synthvid_version == SYNTHVID_VERSION_WIN7 &&
  	     (x > SYNTHVID_WIDTH_MAX_WIN7 || y > SYNTHVID_HEIGHT_MAX_WIN7))) {
  		pr_err("Screen resolution option is out of range: skipped
  ");
  		return;
  	}
  
  	screen_width = x;
  	screen_height = y;
  	return;
  }
  
  
  /* Get framebuffer memory from Hyper-V video pci space */
  static int hvfb_getmem(struct fb_info *info)
  {
  	struct pci_dev *pdev;
  	ulong fb_phys;
  	void __iomem *fb_virt;
  
  	pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
  			      PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
  	if (!pdev) {
  		pr_err("Unable to find PCI Hyper-V video
  ");
  		return -ENODEV;
  	}
  
  	if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM) ||
  	    pci_resource_len(pdev, 0) < screen_fb_size)
  		goto err1;
  
  	fb_phys = pci_resource_end(pdev, 0) - screen_fb_size + 1;
  	if (!request_mem_region(fb_phys, screen_fb_size, KBUILD_MODNAME))
  		goto err1;
  
  	fb_virt = ioremap(fb_phys, screen_fb_size);
  	if (!fb_virt)
  		goto err2;
  
  	info->apertures = alloc_apertures(1);
  	if (!info->apertures)
  		goto err3;
  
  	info->apertures->ranges[0].base = pci_resource_start(pdev, 0);
  	info->apertures->ranges[0].size = pci_resource_len(pdev, 0);
  	info->fix.smem_start = fb_phys;
  	info->fix.smem_len = screen_fb_size;
  	info->screen_base = fb_virt;
  	info->screen_size = screen_fb_size;
  
  	pci_dev_put(pdev);
  	return 0;
  
  err3:
  	iounmap(fb_virt);
  err2:
  	release_mem_region(fb_phys, screen_fb_size);
  err1:
  	pci_dev_put(pdev);
  	return -ENOMEM;
  }
  
  /* Release the framebuffer */
  static void hvfb_putmem(struct fb_info *info)
  {
  	iounmap(info->screen_base);
  	release_mem_region(info->fix.smem_start, screen_fb_size);
  }
  
  
  static int hvfb_probe(struct hv_device *hdev,
  		      const struct hv_vmbus_device_id *dev_id)
  {
  	struct fb_info *info;
  	struct hvfb_par *par;
  	int ret;
  
  	info = framebuffer_alloc(sizeof(struct hvfb_par), &hdev->device);
  	if (!info) {
  		pr_err("No memory for framebuffer info
  ");
  		return -ENOMEM;
  	}
  
  	par = info->par;
  	par->info = info;
  	par->fb_ready = false;
  	init_completion(&par->wait);
  	INIT_DELAYED_WORK(&par->dwork, hvfb_update_work);
  
  	/* Connect to VSP */
  	hv_set_drvdata(hdev, info);
  	ret = synthvid_connect_vsp(hdev);
  	if (ret) {
  		pr_err("Unable to connect to VSP
  ");
  		goto error1;
  	}
  
  	ret = hvfb_getmem(info);
  	if (ret) {
  		pr_err("No memory for framebuffer
  ");
  		goto error2;
  	}
  
  	hvfb_get_option(info);
  	pr_info("Screen resolution: %dx%d, Color depth: %d
  ",
  		screen_width, screen_height, screen_depth);
  
  
  	/* Set up fb_info */
  	info->flags = FBINFO_DEFAULT;
  
  	info->var.xres_virtual = info->var.xres = screen_width;
  	info->var.yres_virtual = info->var.yres = screen_height;
  	info->var.bits_per_pixel = screen_depth;
  
  	if (info->var.bits_per_pixel == 16) {
  		info->var.red = (struct fb_bitfield){11, 5, 0};
  		info->var.green = (struct fb_bitfield){5, 6, 0};
  		info->var.blue = (struct fb_bitfield){0, 5, 0};
  		info->var.transp = (struct fb_bitfield){0, 0, 0};
  	} else {
  		info->var.red = (struct fb_bitfield){16, 8, 0};
  		info->var.green = (struct fb_bitfield){8, 8, 0};
  		info->var.blue = (struct fb_bitfield){0, 8, 0};
  		info->var.transp = (struct fb_bitfield){24, 8, 0};
  	}
  
  	info->var.activate = FB_ACTIVATE_NOW;
  	info->var.height = -1;
  	info->var.width = -1;
  	info->var.vmode = FB_VMODE_NONINTERLACED;
  
  	strcpy(info->fix.id, KBUILD_MODNAME);
  	info->fix.type = FB_TYPE_PACKED_PIXELS;
  	info->fix.visual = FB_VISUAL_TRUECOLOR;
  	info->fix.line_length = screen_width * screen_depth / 8;
  	info->fix.accel = FB_ACCEL_NONE;
  
  	info->fbops = &hvfb_ops;
  	info->pseudo_palette = par->pseudo_palette;
  
  	/* Send config to host */
  	ret = synthvid_send_config(hdev);
  	if (ret)
  		goto error;
  
  	ret = register_framebuffer(info);
  	if (ret) {
  		pr_err("Unable to register framebuffer
  ");
  		goto error;
  	}
  
  	par->fb_ready = true;
  
  	return 0;
  
  error:
  	hvfb_putmem(info);
  error2:
  	vmbus_close(hdev->channel);
  error1:
  	cancel_delayed_work_sync(&par->dwork);
  	hv_set_drvdata(hdev, NULL);
  	framebuffer_release(info);
  	return ret;
  }
  
  
  static int hvfb_remove(struct hv_device *hdev)
  {
  	struct fb_info *info = hv_get_drvdata(hdev);
  	struct hvfb_par *par = info->par;
  
  	par->update = false;
  	par->fb_ready = false;
  
  	unregister_framebuffer(info);
  	cancel_delayed_work_sync(&par->dwork);
  
  	vmbus_close(hdev->channel);
  	hv_set_drvdata(hdev, NULL);
  
  	hvfb_putmem(info);
  	framebuffer_release(info);
  
  	return 0;
  }
  
  
  static DEFINE_PCI_DEVICE_TABLE(pci_stub_id_table) = {
  	{
  		.vendor      = PCI_VENDOR_ID_MICROSOFT,
  		.device      = PCI_DEVICE_ID_HYPERV_VIDEO,
  	},
  	{ /* end of list */ }
  };
  
  static const struct hv_vmbus_device_id id_table[] = {
  	/* Synthetic Video Device GUID */
  	{HV_SYNTHVID_GUID},
  	{}
  };
  
  MODULE_DEVICE_TABLE(pci, pci_stub_id_table);
  MODULE_DEVICE_TABLE(vmbus, id_table);
  
  static struct hv_driver hvfb_drv = {
  	.name = KBUILD_MODNAME,
  	.id_table = id_table,
  	.probe = hvfb_probe,
  	.remove = hvfb_remove,
  };
  
  static int hvfb_pci_stub_probe(struct pci_dev *pdev,
  			       const struct pci_device_id *ent)
  {
  	return 0;
  }
  
  static void hvfb_pci_stub_remove(struct pci_dev *pdev)
  {
  }
  
  static struct pci_driver hvfb_pci_stub_driver = {
  	.name =		KBUILD_MODNAME,
  	.id_table =	pci_stub_id_table,
  	.probe =	hvfb_pci_stub_probe,
  	.remove =	hvfb_pci_stub_remove,
  };
  
  static int __init hvfb_drv_init(void)
  {
  	int ret;
  
  	ret = vmbus_driver_register(&hvfb_drv);
  	if (ret != 0)
  		return ret;
  
  	ret = pci_register_driver(&hvfb_pci_stub_driver);
  	if (ret != 0) {
  		vmbus_driver_unregister(&hvfb_drv);
  		return ret;
  	}
  
  	return 0;
  }
  
  static void __exit hvfb_drv_exit(void)
  {
  	pci_unregister_driver(&hvfb_pci_stub_driver);
  	vmbus_driver_unregister(&hvfb_drv);
  }
  
  module_init(hvfb_drv_init);
  module_exit(hvfb_drv_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Microsoft Hyper-V Synthetic Video Frame Buffer Driver");