// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Copyright (c) 2009, Citrix Systems, Inc.
 *  Copyright (c) 2010, Microsoft Corporation.
 *  Copyright (c) 2011, Novell Inc.
 */
#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);

                pm_wakeup_hard_event(&input_dev->device->device);

                break;
        default:
                pr_err("unsupported hid msg type - type %d len %d\n",
                       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\n",
                                        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;
        unsigned long 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)\n",
                       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 int mousevsc_hid_raw_request(struct hid_device *hid,
                                    unsigned char report_num,
                                    __u8 *buf, size_t len,
                                    unsigned char rtype,
                                    int reqtype)
{
        return 0;
}

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,
        .raw_request = mousevsc_hid_raw_request,
};

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\n");
                goto probe_err2;
        }

        ret = hid_hw_start(hid_dev, HID_CONNECT_HIDINPUT | HID_CONNECT_HIDDEV);

        if (ret) {
                hid_err(hid_dev, "hw start failed\n");
                goto probe_err2;
        }

        device_init_wakeup(&device->device, true);

        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);

        device_init_wakeup(&dev->device, false);
        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,
        .driver = {
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
        },
};

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_DESCRIPTION("Microsoft Hyper-V Synthetic HID Driver");

module_init(mousevsc_init);
module_exit(mousevsc_exit);