/*
   *  Copyright (c) 2009, Citrix Systems, Inc.
   *  Copyright (c) 2010, Microsoft Corporation.
   *  Copyright (c) 2011, Novell Inc.
   *
   *  This program is free software; you can redistribute it and/or modify it
   *  under the terms and conditions of the GNU General Public License,
   *  version 2, as published by the Free Software Foundation.
   *
   *  This program is distributed in the hope it will be useful, but WITHOUT
   *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   *  more details.
   */
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/device.h>
  #include <linux/completion.h>
  #include <linux/input.h>
  #include <linux/hid.h>
  #include <linux/hiddev.h>
  #include <linux/hyperv.h>
  
  
  struct hv_input_dev_info {
  	unsigned int size;
  	unsigned short vendor;
  	unsigned short product;
  	unsigned short version;
  	unsigned short reserved[11];
  };
  
  /* The maximum size of a synthetic input message. */
  #define SYNTHHID_MAX_INPUT_REPORT_SIZE 16
  
  /*
   * Current version
   *
   * History:
   * Beta, RC < 2008/1/22        1,0
   * RC > 2008/1/22              2,0
   */
  #define SYNTHHID_INPUT_VERSION_MAJOR	2
  #define SYNTHHID_INPUT_VERSION_MINOR	0
  #define SYNTHHID_INPUT_VERSION		(SYNTHHID_INPUT_VERSION_MINOR | \
  					 (SYNTHHID_INPUT_VERSION_MAJOR << 16))
  
  
  #pragma pack(push, 1)
  /*
   * Message types in the synthetic input protocol
   */
  enum synthhid_msg_type {
  	SYNTH_HID_PROTOCOL_REQUEST,
  	SYNTH_HID_PROTOCOL_RESPONSE,
  	SYNTH_HID_INITIAL_DEVICE_INFO,
  	SYNTH_HID_INITIAL_DEVICE_INFO_ACK,
  	SYNTH_HID_INPUT_REPORT,
  	SYNTH_HID_MAX
  };
  
  /*
   * Basic message structures.
   */
  struct synthhid_msg_hdr {
  	enum synthhid_msg_type type;
  	u32 size;
  };
  
  struct synthhid_msg {
  	struct synthhid_msg_hdr header;
  	char data[1]; /* Enclosed message */
  };
  
  union synthhid_version {
  	struct {
  		u16 minor_version;
  		u16 major_version;
  	};
  	u32 version;
  };
  
  /*
   * Protocol messages
   */
  struct synthhid_protocol_request {
  	struct synthhid_msg_hdr header;
  	union synthhid_version version_requested;
  };
  
  struct synthhid_protocol_response {
  	struct synthhid_msg_hdr header;
  	union synthhid_version version_requested;
  	unsigned char approved;
  };
  
  struct synthhid_device_info {
  	struct synthhid_msg_hdr header;
  	struct hv_input_dev_info hid_dev_info;
  	struct hid_descriptor hid_descriptor;
  };
  
  struct synthhid_device_info_ack {
  	struct synthhid_msg_hdr header;
  	unsigned char reserved;
  };
  
  struct synthhid_input_report {
  	struct synthhid_msg_hdr header;
  	char buffer[1];
  };
  
  #pragma pack(pop)
  
  #define INPUTVSC_SEND_RING_BUFFER_SIZE		(10*PAGE_SIZE)
  #define INPUTVSC_RECV_RING_BUFFER_SIZE		(10*PAGE_SIZE)
  
  
  enum pipe_prot_msg_type {
  	PIPE_MESSAGE_INVALID,
  	PIPE_MESSAGE_DATA,
  	PIPE_MESSAGE_MAXIMUM
  };
  
  
  struct pipe_prt_msg {
  	enum pipe_prot_msg_type type;
  	u32 size;
  	char data[1];
  };
  
  struct  mousevsc_prt_msg {
  	enum pipe_prot_msg_type type;
  	u32 size;
  	union {
  		struct synthhid_protocol_request request;
  		struct synthhid_protocol_response response;
  		struct synthhid_device_info_ack ack;
  	};
  };
  
  /*
   * Represents an mousevsc device
   */
  struct mousevsc_dev {
  	struct hv_device	*device;
  	bool			init_complete;
  	bool			connected;
  	struct mousevsc_prt_msg	protocol_req;
  	struct mousevsc_prt_msg	protocol_resp;
  	/* Synchronize the request/response if needed */
  	struct completion	wait_event;
  	int			dev_info_status;
  
  	struct hid_descriptor	*hid_desc;
  	unsigned char		*report_desc;
  	u32			report_desc_size;
  	struct hv_input_dev_info hid_dev_info;
  	struct hid_device       *hid_device;
  	u8			input_buf[HID_MAX_BUFFER_SIZE];
  };
  
  
  static struct mousevsc_dev *mousevsc_alloc_device(struct hv_device *device)
  {
  	struct mousevsc_dev *input_dev;
  
  	input_dev = kzalloc(sizeof(struct mousevsc_dev), GFP_KERNEL);
  
  	if (!input_dev)
  		return NULL;
  
  	input_dev->device = device;
  	hv_set_drvdata(device, input_dev);
  	init_completion(&input_dev->wait_event);
  	input_dev->init_complete = false;
  
  	return input_dev;
  }
  
  static void mousevsc_free_device(struct mousevsc_dev *device)
  {
  	kfree(device->hid_desc);
  	kfree(device->report_desc);
  	hv_set_drvdata(device->device, NULL);
  	kfree(device);
  }
  
  static void mousevsc_on_receive_device_info(struct mousevsc_dev *input_device,
  				struct synthhid_device_info *device_info)
  {
  	int ret = 0;
  	struct hid_descriptor *desc;
  	struct mousevsc_prt_msg ack;
  
  	input_device->dev_info_status = -ENOMEM;
  
  	input_device->hid_dev_info = device_info->hid_dev_info;
  	desc = &device_info->hid_descriptor;
  	if (desc->bLength == 0)
  		goto cleanup;
  
  	input_device->hid_desc = kmemdup(desc, desc->bLength, GFP_ATOMIC);
  
  	if (!input_device->hid_desc)
  		goto cleanup;
  
  	input_device->report_desc_size = desc->desc[0].wDescriptorLength;
  	if (input_device->report_desc_size == 0) {
  		input_device->dev_info_status = -EINVAL;
  		goto cleanup;
  	}
  
  	input_device->report_desc = kzalloc(input_device->report_desc_size,
  					  GFP_ATOMIC);
  
  	if (!input_device->report_desc) {
  		input_device->dev_info_status = -ENOMEM;
  		goto cleanup;
  	}
  
  	memcpy(input_device->report_desc,
  	       ((unsigned char *)desc) + desc->bLength,
  	       desc->desc[0].wDescriptorLength);
  
  	/* Send the ack */
  	memset(&ack, 0, sizeof(struct mousevsc_prt_msg));
  
  	ack.type = PIPE_MESSAGE_DATA;
  	ack.size = sizeof(struct synthhid_device_info_ack);
  
  	ack.ack.header.type = SYNTH_HID_INITIAL_DEVICE_INFO_ACK;
  	ack.ack.header.size = 1;
  	ack.ack.reserved = 0;
  
  	ret = vmbus_sendpacket(input_device->device->channel,
  			&ack,
  			sizeof(struct pipe_prt_msg) - sizeof(unsigned char) +
  			sizeof(struct synthhid_device_info_ack),
  			(unsigned long)&ack,
  			VM_PKT_DATA_INBAND,
  			VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
  
  	if (!ret)
  		input_device->dev_info_status = 0;
  
  cleanup:
  	complete(&input_device->wait_event);
  
  	return;
  }
  
  static void mousevsc_on_receive(struct hv_device *device,
  				struct vmpacket_descriptor *packet)
  {
  	struct pipe_prt_msg *pipe_msg;
  	struct synthhid_msg *hid_msg;
  	struct mousevsc_dev *input_dev = hv_get_drvdata(device);
  	struct synthhid_input_report *input_report;
  	size_t len;
  
  	pipe_msg = (struct pipe_prt_msg *)((unsigned long)packet +
  						(packet->offset8 << 3));
  
  	if (pipe_msg->type != PIPE_MESSAGE_DATA)
  		return;
  
  	hid_msg = (struct synthhid_msg *)pipe_msg->data;
  
  	switch (hid_msg->header.type) {
  	case SYNTH_HID_PROTOCOL_RESPONSE:
  		/*
  		 * While it will be impossible for us to protect against
  		 * malicious/buggy hypervisor/host, add a check here to
  		 * ensure we don't corrupt memory.
  		 */
  		if ((pipe_msg->size + sizeof(struct pipe_prt_msg)
  			- sizeof(unsigned char))
  			> sizeof(struct mousevsc_prt_msg)) {
  			WARN_ON(1);
  			break;
  		}
  
  		memcpy(&input_dev->protocol_resp, pipe_msg,
  		       pipe_msg->size + sizeof(struct pipe_prt_msg) -
  		       sizeof(unsigned char));
  		complete(&input_dev->wait_event);
  		break;
  
  	case SYNTH_HID_INITIAL_DEVICE_INFO:
  		WARN_ON(pipe_msg->size < sizeof(struct hv_input_dev_info));
  
  		/*
  		 * Parse out the device info into device attr,
  		 * hid desc and report desc
  		 */
  		mousevsc_on_receive_device_info(input_dev,
  			(struct synthhid_device_info *)pipe_msg->data);
  		break;
  	case SYNTH_HID_INPUT_REPORT:
  		input_report =
  			(struct synthhid_input_report *)pipe_msg->data;
  		if (!input_dev->init_complete)
  			break;
  
  		len = min(input_report->header.size,
  			  (u32)sizeof(input_dev->input_buf));
  		memcpy(input_dev->input_buf, input_report->buffer, len);
  		hid_input_report(input_dev->hid_device, HID_INPUT_REPORT,
  				 input_dev->input_buf, len, 1);
  		break;
  	default:
  		pr_err("unsupported hid msg type - type %d len %d",
  		       hid_msg->header.type, hid_msg->header.size);
  		break;
  	}
  
  }
  
  static void mousevsc_on_channel_callback(void *context)
  {
  	const int packet_size = 0x100;
  	int ret;
  	struct hv_device *device = context;
  	u32 bytes_recvd;
  	u64 req_id;
  	struct vmpacket_descriptor *desc;
  	unsigned char	*buffer;
  	int	bufferlen = packet_size;
  
  	buffer = kmalloc(bufferlen, GFP_ATOMIC);
  	if (!buffer)
  		return;
  
  	do {
  		ret = vmbus_recvpacket_raw(device->channel, buffer,
  					bufferlen, &bytes_recvd, &req_id);
  
  		switch (ret) {
  		case 0:
  			if (bytes_recvd <= 0) {
  				kfree(buffer);
  				return;
  			}
  			desc = (struct vmpacket_descriptor *)buffer;
  
  			switch (desc->type) {
  			case VM_PKT_COMP:
  				break;
  
  			case VM_PKT_DATA_INBAND:
  				mousevsc_on_receive(device, desc);
  				break;
  
  			default:
  				pr_err("unhandled packet type %d, tid %llx len %d
  ",
  					desc->type, req_id, bytes_recvd);
  				break;
  			}
  
  			break;
  
  		case -ENOBUFS:
  			kfree(buffer);
  			/* Handle large packet */
  			bufferlen = bytes_recvd;
  			buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
  
  			if (!buffer)
  				return;
  
  			break;
  		}
  	} while (1);
  
  }
  
  static int mousevsc_connect_to_vsp(struct hv_device *device)
  {
  	int ret = 0;
  	int t;
  	struct mousevsc_dev *input_dev = hv_get_drvdata(device);
  	struct mousevsc_prt_msg *request;
  	struct mousevsc_prt_msg *response;
  
  	request = &input_dev->protocol_req;
  	memset(request, 0, sizeof(struct mousevsc_prt_msg));
  
  	request->type = PIPE_MESSAGE_DATA;
  	request->size = sizeof(struct synthhid_protocol_request);
  	request->request.header.type = SYNTH_HID_PROTOCOL_REQUEST;
  	request->request.header.size = sizeof(unsigned int);
  	request->request.version_requested.version = SYNTHHID_INPUT_VERSION;
  
  	ret = vmbus_sendpacket(device->channel, request,
  				sizeof(struct pipe_prt_msg) -
  				sizeof(unsigned char) +
  				sizeof(struct synthhid_protocol_request),
  				(unsigned long)request,
  				VM_PKT_DATA_INBAND,
  				VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
  	if (ret)
  		goto cleanup;
  
  	t = wait_for_completion_timeout(&input_dev->wait_event, 5*HZ);
  	if (!t) {
  		ret = -ETIMEDOUT;
  		goto cleanup;
  	}
  
  	response = &input_dev->protocol_resp;
  
  	if (!response->response.approved) {
  		pr_err("synthhid protocol request failed (version %d)
  ",
  		       SYNTHHID_INPUT_VERSION);
  		ret = -ENODEV;
  		goto cleanup;
  	}
  
  	t = wait_for_completion_timeout(&input_dev->wait_event, 5*HZ);
  	if (!t) {
  		ret = -ETIMEDOUT;
  		goto cleanup;
  	}
  
  	/*
  	 * We should have gotten the device attr, hid desc and report
  	 * desc at this point
  	 */
  	ret = input_dev->dev_info_status;
  
  cleanup:
  	return ret;
  }
  
  static int mousevsc_hid_parse(struct hid_device *hid)
  {
  	struct hv_device *dev = hid_get_drvdata(hid);
  	struct mousevsc_dev *input_dev = hv_get_drvdata(dev);
  
  	return hid_parse_report(hid, input_dev->report_desc,
  				input_dev->report_desc_size);
  }
  
  static int mousevsc_hid_open(struct hid_device *hid)
  {
  	return 0;
  }
  
  static int mousevsc_hid_start(struct hid_device *hid)
  {
  	return 0;
  }
  
  static void mousevsc_hid_close(struct hid_device *hid)
  {
  }
  
  static void mousevsc_hid_stop(struct hid_device *hid)
  {
  }
  
  static struct hid_ll_driver mousevsc_ll_driver = {
  	.parse = mousevsc_hid_parse,
  	.open = mousevsc_hid_open,
  	.close = mousevsc_hid_close,
  	.start = mousevsc_hid_start,
  	.stop = mousevsc_hid_stop,
  };
  
  static struct hid_driver mousevsc_hid_driver;
  
  static int mousevsc_probe(struct hv_device *device,
  			const struct hv_vmbus_device_id *dev_id)
  {
  	int ret;
  	struct mousevsc_dev *input_dev;
  	struct hid_device *hid_dev;
  
  	input_dev = mousevsc_alloc_device(device);
  
  	if (!input_dev)
  		return -ENOMEM;
  
  	ret = vmbus_open(device->channel,
  		INPUTVSC_SEND_RING_BUFFER_SIZE,
  		INPUTVSC_RECV_RING_BUFFER_SIZE,
  		NULL,
  		0,
  		mousevsc_on_channel_callback,
  		device
  		);
  
  	if (ret)
  		goto probe_err0;
  
  	ret = mousevsc_connect_to_vsp(device);
  
  	if (ret)
  		goto probe_err1;
  
  	/* workaround SA-167 */
  	if (input_dev->report_desc[14] == 0x25)
  		input_dev->report_desc[14] = 0x29;
  
  	hid_dev = hid_allocate_device();
  	if (IS_ERR(hid_dev)) {
  		ret = PTR_ERR(hid_dev);
  		goto probe_err1;
  	}
  
  	hid_dev->ll_driver = &mousevsc_ll_driver;
  	hid_dev->driver = &mousevsc_hid_driver;
  	hid_dev->bus = BUS_VIRTUAL;
  	hid_dev->vendor = input_dev->hid_dev_info.vendor;
  	hid_dev->product = input_dev->hid_dev_info.product;
  	hid_dev->version = input_dev->hid_dev_info.version;
  	input_dev->hid_device = hid_dev;
  
  	sprintf(hid_dev->name, "%s", "Microsoft Vmbus HID-compliant Mouse");
  
  	hid_set_drvdata(hid_dev, device);
  
  	ret = hid_add_device(hid_dev);
  	if (ret)
  		goto probe_err1;
  
  
  	ret = hid_parse(hid_dev);
  	if (ret) {
  		hid_err(hid_dev, "parse failed
  ");
  		goto probe_err2;
  	}
  
  	ret = hid_hw_start(hid_dev, HID_CONNECT_HIDINPUT | HID_CONNECT_HIDDEV);
  
  	if (ret) {
  		hid_err(hid_dev, "hw start failed
  ");
  		goto probe_err2;
  	}
  
  	input_dev->connected = true;
  	input_dev->init_complete = true;
  
  	return ret;
  
  probe_err2:
  	hid_destroy_device(hid_dev);
  
  probe_err1:
  	vmbus_close(device->channel);
  
  probe_err0:
  	mousevsc_free_device(input_dev);
  
  	return ret;
  }
  
  
  static int mousevsc_remove(struct hv_device *dev)
  {
  	struct mousevsc_dev *input_dev = hv_get_drvdata(dev);
  
  	vmbus_close(dev->channel);
  	hid_hw_stop(input_dev->hid_device);
  	hid_destroy_device(input_dev->hid_device);
  	mousevsc_free_device(input_dev);
  
  	return 0;
  }
  
  static const struct hv_vmbus_device_id id_table[] = {
  	/* Mouse guid */
  	{ HV_MOUSE_GUID, },
  	{ },
  };
  
  MODULE_DEVICE_TABLE(vmbus, id_table);
  
  static struct  hv_driver mousevsc_drv = {
  	.name = KBUILD_MODNAME,
  	.id_table = id_table,
  	.probe = mousevsc_probe,
  	.remove = mousevsc_remove,
  };
  
  static int __init mousevsc_init(void)
  {
  	return vmbus_driver_register(&mousevsc_drv);
  }
  
  static void __exit mousevsc_exit(void)
  {
  	vmbus_driver_unregister(&mousevsc_drv);
  }
  
  MODULE_LICENSE("GPL");
  module_init(mousevsc_init);
  module_exit(mousevsc_exit);