/*
 * Driver for Virtual PS/2 Mouse on VMware and QEMU hypervisors.
 *
 * Copyright (C) 2014, VMware, Inc. All Rights Reserved.
 *
 * 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.
 *
 * Twin device code is hugely inspired by the ALPS driver.
 * Authors:
 *   Dmitry Torokhov <dmitry.torokhov@gmail.com>
 *   Thomas Hellstrom <thellstrom@vmware.com>
 */

#include <linux/input.h>
#include <linux/serio.h>
#include <linux/libps2.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <asm/hypervisor.h>

#include "psmouse.h"
#include "vmmouse.h"

#define VMMOUSE_PROTO_MAGIC                     0x564D5868U
#define VMMOUSE_PROTO_PORT                      0x5658

/*
 * Main commands supported by the vmmouse hypervisor port.
 */
#define VMMOUSE_PROTO_CMD_GETVERSION            10
#define VMMOUSE_PROTO_CMD_ABSPOINTER_DATA       39
#define VMMOUSE_PROTO_CMD_ABSPOINTER_STATUS     40
#define VMMOUSE_PROTO_CMD_ABSPOINTER_COMMAND    41
#define VMMOUSE_PROTO_CMD_ABSPOINTER_RESTRICT   86

/*
 * Subcommands for VMMOUSE_PROTO_CMD_ABSPOINTER_COMMAND
 */
#define VMMOUSE_CMD_ENABLE                      0x45414552U
#define VMMOUSE_CMD_DISABLE                     0x000000f5U
#define VMMOUSE_CMD_REQUEST_RELATIVE            0x4c455252U
#define VMMOUSE_CMD_REQUEST_ABSOLUTE            0x53424152U

#define VMMOUSE_ERROR                           0xffff0000U

#define VMMOUSE_VERSION_ID                      0x3442554aU

#define VMMOUSE_RELATIVE_PACKET                 0x00010000U

#define VMMOUSE_LEFT_BUTTON                     0x20
#define VMMOUSE_RIGHT_BUTTON                    0x10
#define VMMOUSE_MIDDLE_BUTTON                   0x08

/*
 * VMMouse Restrict command
 */
#define VMMOUSE_RESTRICT_ANY                    0x00
#define VMMOUSE_RESTRICT_CPL0                   0x01
#define VMMOUSE_RESTRICT_IOPL                   0x02

#define VMMOUSE_MAX_X                           0xFFFF
#define VMMOUSE_MAX_Y                           0xFFFF

#define VMMOUSE_VENDOR "VMware"
#define VMMOUSE_NAME   "VMMouse"

/**
 * struct vmmouse_data - private data structure for the vmmouse driver
 *
 * @abs_dev: "Absolute" device used to report absolute mouse movement.
 * @phys: Physical path for the absolute device.
 * @dev_name: Name attribute name for the absolute device.
 */
struct vmmouse_data {
        struct input_dev *abs_dev;
        char phys[32];
        char dev_name[128];
};

/**
 * Hypervisor-specific bi-directional communication channel
 * implementing the vmmouse protocol. Should never execute on
 * bare metal hardware.
 */
#define VMMOUSE_CMD(cmd, in1, out1, out2, out3, out4)   \
({                                                      \
        unsigned long __dummy1, __dummy2;               \
        __asm__ __volatile__ ("inl %%dx" :              \
                "=a"(out1),                             \
                "=b"(out2),                             \
                "=c"(out3),                             \
                "=d"(out4),                             \
                "=S"(__dummy1),                         \
                "=D"(__dummy2) :                        \
                "a"(VMMOUSE_PROTO_MAGIC),               \
                "b"(in1),                               \
                "c"(VMMOUSE_PROTO_CMD_##cmd),           \
                "d"(VMMOUSE_PROTO_PORT) :               \
                "memory");                              \
})

/**
 * vmmouse_report_button - report button state on the correct input device
 *
 * @psmouse:  Pointer to the psmouse struct
 * @abs_dev:  The absolute input device
 * @rel_dev:  The relative input device
 * @pref_dev: The preferred device for reporting
 * @code:     Button code
 * @value:    Button value
 *
 * Report @value and @code on @pref_dev, unless the button is already
 * pressed on the other device, in which case the state is reported on that
 * device.
 */
static void vmmouse_report_button(struct psmouse *psmouse,
                                  struct input_dev *abs_dev,
                                  struct input_dev *rel_dev,
                                  struct input_dev *pref_dev,
                                  unsigned int code, int value)
{
        if (test_bit(code, abs_dev->key))
                pref_dev = abs_dev;
        else if (test_bit(code, rel_dev->key))
                pref_dev = rel_dev;

        input_report_key(pref_dev, code, value);
}

/**
 * vmmouse_report_events - process events on the vmmouse communications channel
 *
 * @psmouse: Pointer to the psmouse struct
 *
 * This function pulls events from the vmmouse communications channel and
 * reports them on the correct (absolute or relative) input device. When the
 * communications channel is drained, or if we've processed more than 255
 * psmouse commands, the function returns PSMOUSE_FULL_PACKET. If there is a
 * host- or synchronization error, the function returns PSMOUSE_BAD_DATA in
 * the hope that the caller will reset the communications channel.
 */
static psmouse_ret_t vmmouse_report_events(struct psmouse *psmouse)
{
        struct input_dev *rel_dev = psmouse->dev;
        struct vmmouse_data *priv = psmouse->private;
        struct input_dev *abs_dev = priv->abs_dev;
        struct input_dev *pref_dev;
        u32 status, x, y, z;
        u32 dummy1, dummy2, dummy3;
        unsigned int queue_length;
        unsigned int count = 255;

        while (count--) {
                /* See if we have motion data. */
                VMMOUSE_CMD(ABSPOINTER_STATUS, 0,
                            status, dummy1, dummy2, dummy3);
                if ((status & VMMOUSE_ERROR) == VMMOUSE_ERROR) {
                        psmouse_err(psmouse, "failed to fetch status data\n");
                        /*
                         * After a few attempts this will result in
                         * reconnect.
                         */
                        return PSMOUSE_BAD_DATA;
                }

                queue_length = status & 0xffff;
                if (queue_length == 0)
                        break;

                if (queue_length % 4) {
                        psmouse_err(psmouse, "invalid queue length\n");
                        return PSMOUSE_BAD_DATA;
                }

                /* Now get it */
                VMMOUSE_CMD(ABSPOINTER_DATA, 4, status, x, y, z);

                /*
                 * And report what we've got. Prefer to report button
                 * events on the same device where we report motion events.
                 * This doesn't work well with the mouse wheel, though. See
                 * below. Ideally we would want to report that on the
                 * preferred device as well.
                 */
                if (status & VMMOUSE_RELATIVE_PACKET) {
                        pref_dev = rel_dev;
                        input_report_rel(rel_dev, REL_X, (s32)x);
                        input_report_rel(rel_dev, REL_Y, -(s32)y);
                } else {
                        pref_dev = abs_dev;
                        input_report_abs(abs_dev, ABS_X, x);
                        input_report_abs(abs_dev, ABS_Y, y);
                }

                /* Xorg seems to ignore wheel events on absolute devices */
                input_report_rel(rel_dev, REL_WHEEL, -(s8)((u8) z));

                vmmouse_report_button(psmouse, abs_dev, rel_dev,
                                      pref_dev, BTN_LEFT,
                                      status & VMMOUSE_LEFT_BUTTON);
                vmmouse_report_button(psmouse, abs_dev, rel_dev,
                                      pref_dev, BTN_RIGHT,
                                      status & VMMOUSE_RIGHT_BUTTON);
                vmmouse_report_button(psmouse, abs_dev, rel_dev,
                                      pref_dev, BTN_MIDDLE,
                                      status & VMMOUSE_MIDDLE_BUTTON);
                input_sync(abs_dev);
                input_sync(rel_dev);
        }

        return PSMOUSE_FULL_PACKET;
}

/**
 * vmmouse_process_byte - process data on the ps/2 channel
 *
 * @psmouse: Pointer to the psmouse struct
 *
 * When the ps/2 channel indicates that there is vmmouse data available,
 * call vmmouse channel processing. Otherwise, continue to accept bytes. If
 * there is a synchronization or communication data error, return
 * PSMOUSE_BAD_DATA in the hope that the caller will reset the mouse.
 */
static psmouse_ret_t vmmouse_process_byte(struct psmouse *psmouse)
{
        unsigned char *packet = psmouse->packet;

        switch (psmouse->pktcnt) {
        case 1:
                return (packet[0] & 0x8) == 0x8 ?
                        PSMOUSE_GOOD_DATA : PSMOUSE_BAD_DATA;

        case 2:
                return PSMOUSE_GOOD_DATA;

        default:
                return vmmouse_report_events(psmouse);
        }
}

/**
 * vmmouse_disable - Disable vmmouse
 *
 * @psmouse: Pointer to the psmouse struct
 *
 * Tries to disable vmmouse mode.
 */
static void vmmouse_disable(struct psmouse *psmouse)
{
        u32 status;
        u32 dummy1, dummy2, dummy3, dummy4;

        VMMOUSE_CMD(ABSPOINTER_COMMAND, VMMOUSE_CMD_DISABLE,
                    dummy1, dummy2, dummy3, dummy4);

        VMMOUSE_CMD(ABSPOINTER_STATUS, 0,
                    status, dummy1, dummy2, dummy3);

        if ((status & VMMOUSE_ERROR) != VMMOUSE_ERROR)
                psmouse_warn(psmouse, "failed to disable vmmouse device\n");
}

/**
 * vmmouse_enable - Enable vmmouse and request absolute mode.
 *
 * @psmouse: Pointer to the psmouse struct
 *
 * Tries to enable vmmouse mode. Performs basic checks and requests
 * absolute vmmouse mode.
 * Returns 0 on success, -ENODEV on failure.
 */
static int vmmouse_enable(struct psmouse *psmouse)
{
        u32 status, version;
        u32 dummy1, dummy2, dummy3, dummy4;

        /*
         * Try enabling the device. If successful, we should be able to
         * read valid version ID back from it.
         */
        VMMOUSE_CMD(ABSPOINTER_COMMAND, VMMOUSE_CMD_ENABLE,
                    dummy1, dummy2, dummy3, dummy4);

        /*
         * See if version ID can be retrieved.
         */
        VMMOUSE_CMD(ABSPOINTER_STATUS, 0, status, dummy1, dummy2, dummy3);
        if ((status & 0x0000ffff) == 0) {
                psmouse_dbg(psmouse, "empty flags - assuming no device\n");
                return -ENXIO;
        }

        VMMOUSE_CMD(ABSPOINTER_DATA, 1 /* single item */,
                    version, dummy1, dummy2, dummy3);
        if (version != VMMOUSE_VERSION_ID) {
                psmouse_dbg(psmouse, "Unexpected version value: %u vs %u\n",
                            (unsigned) version, VMMOUSE_VERSION_ID);
                vmmouse_disable(psmouse);
                return -ENXIO;
        }

        /*
         * Restrict ioport access, if possible.
         */
        VMMOUSE_CMD(ABSPOINTER_RESTRICT, VMMOUSE_RESTRICT_CPL0,
                    dummy1, dummy2, dummy3, dummy4);

        VMMOUSE_CMD(ABSPOINTER_COMMAND, VMMOUSE_CMD_REQUEST_ABSOLUTE,
                    dummy1, dummy2, dummy3, dummy4);

        return 0;
}

/*
 * Array of supported hypervisors.
 */
static const struct hypervisor_x86 *vmmouse_supported_hypervisors[] = {
        &x86_hyper_vmware,
#ifdef CONFIG_KVM_GUEST
        &x86_hyper_kvm,
#endif
};

/**
 * vmmouse_check_hypervisor - Check if we're running on a supported hypervisor
 */
static bool vmmouse_check_hypervisor(void)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(vmmouse_supported_hypervisors); i++)
                if (vmmouse_supported_hypervisors[i] == x86_hyper)
                        return true;

        return false;
}

/**
 * vmmouse_detect - Probe whether vmmouse is available
 *
 * @psmouse: Pointer to the psmouse struct
 * @set_properties: Whether to set psmouse name and vendor
 *
 * Returns 0 if vmmouse channel is available. Negative error code if not.
 */
int vmmouse_detect(struct psmouse *psmouse, bool set_properties)
{
        u32 response, version, dummy1, dummy2;

        if (!vmmouse_check_hypervisor()) {
                psmouse_dbg(psmouse,
                            "VMMouse not running on supported hypervisor.\n");
                return -ENXIO;
        }

        /* Check if the device is present */
        response = ~VMMOUSE_PROTO_MAGIC;
        VMMOUSE_CMD(GETVERSION, 0, version, response, dummy1, dummy2);
        if (response != VMMOUSE_PROTO_MAGIC || version == 0xffffffffU)
                return -ENXIO;

        if (set_properties) {
                psmouse->vendor = VMMOUSE_VENDOR;
                psmouse->name = VMMOUSE_NAME;
                psmouse->model = version;
        }

        return 0;
}

/**
 * vmmouse_disconnect - Take down vmmouse driver
 *
 * @psmouse: Pointer to the psmouse struct
 *
 * Takes down vmmouse driver and frees resources set up in vmmouse_init().
 */
static void vmmouse_disconnect(struct psmouse *psmouse)
{
        struct vmmouse_data *priv = psmouse->private;

        vmmouse_disable(psmouse);
        psmouse_reset(psmouse);
        input_unregister_device(priv->abs_dev);
        kfree(priv);
}

/**
 * vmmouse_reconnect - Reset the ps/2 - and vmmouse connections
 *
 * @psmouse: Pointer to the psmouse struct
 *
 * Attempts to reset the mouse connections. Returns 0 on success and
 * -1 on failure.
 */
static int vmmouse_reconnect(struct psmouse *psmouse)
{
        int error;

        psmouse_reset(psmouse);
        vmmouse_disable(psmouse);
        error = vmmouse_enable(psmouse);
        if (error) {
                psmouse_err(psmouse,
                            "Unable to re-enable mouse when reconnecting, err: %d\n",
                            error);
                return error;
        }

        return 0;
}

/**
 * vmmouse_init - Initialize the vmmouse driver
 *
 * @psmouse: Pointer to the psmouse struct
 *
 * Requests the device and tries to enable vmmouse mode.
 * If successful, sets up the input device for relative movement events.
 * It also allocates another input device and sets it up for absolute motion
 * events. Returns 0 on success and -1 on failure.
 */
int vmmouse_init(struct psmouse *psmouse)
{
        struct vmmouse_data *priv;
        struct input_dev *rel_dev = psmouse->dev, *abs_dev;
        int error;

        psmouse_reset(psmouse);
        error = vmmouse_enable(psmouse);
        if (error)
                return error;

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        abs_dev = input_allocate_device();
        if (!priv || !abs_dev) {
                error = -ENOMEM;
                goto init_fail;
        }

        priv->abs_dev = abs_dev;
        psmouse->private = priv;

        /* Set up and register absolute device */
        snprintf(priv->phys, sizeof(priv->phys), "%s/input1",
                 psmouse->ps2dev.serio->phys);

        /* Mimic name setup for relative device in psmouse-base.c */
        snprintf(priv->dev_name, sizeof(priv->dev_name), "%s %s %s",
                 VMMOUSE_PSNAME, VMMOUSE_VENDOR, VMMOUSE_NAME);
        abs_dev->phys = priv->phys;
        abs_dev->name = priv->dev_name;
        abs_dev->id.bustype = BUS_I8042;
        abs_dev->id.vendor = 0x0002;
        abs_dev->id.product = PSMOUSE_VMMOUSE;
        abs_dev->id.version = psmouse->model;
        abs_dev->dev.parent = &psmouse->ps2dev.serio->dev;

        /* Set absolute device capabilities */
        input_set_capability(abs_dev, EV_KEY, BTN_LEFT);
        input_set_capability(abs_dev, EV_KEY, BTN_RIGHT);
        input_set_capability(abs_dev, EV_KEY, BTN_MIDDLE);
        input_set_capability(abs_dev, EV_ABS, ABS_X);
        input_set_capability(abs_dev, EV_ABS, ABS_Y);
        input_set_abs_params(abs_dev, ABS_X, 0, VMMOUSE_MAX_X, 0, 0);
        input_set_abs_params(abs_dev, ABS_Y, 0, VMMOUSE_MAX_Y, 0, 0);

        error = input_register_device(priv->abs_dev);
        if (error)
                goto init_fail;

        /* Add wheel capability to the relative device */
        input_set_capability(rel_dev, EV_REL, REL_WHEEL);

        psmouse->protocol_handler = vmmouse_process_byte;
        psmouse->disconnect = vmmouse_disconnect;
        psmouse->reconnect = vmmouse_reconnect;

        return 0;

init_fail:
        vmmouse_disable(psmouse);
        psmouse_reset(psmouse);
        input_free_device(abs_dev);
        kfree(priv);
        psmouse->private = NULL;

        return error;
}