/*
 * Xen para-virtual input device
 *
 * Copyright (C) 2005 Anthony Liguori <aliguori@us.ibm.com>
 * Copyright (C) 2006-2008 Red Hat, Inc., Markus Armbruster <armbru@redhat.com>
 *
 *  Based on linux/drivers/input/mouse/sermouse.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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/input/mt.h>
#include <linux/slab.h>

#include <asm/xen/hypervisor.h>

#include <xen/xen.h>
#include <xen/events.h>
#include <xen/page.h>
#include <xen/grant_table.h>
#include <xen/interface/grant_table.h>
#include <xen/interface/io/fbif.h>
#include <xen/interface/io/kbdif.h>
#include <xen/xenbus.h>
#include <xen/platform_pci.h>

struct xenkbd_info {
        struct input_dev *kbd;
        struct input_dev *ptr;
        struct input_dev *mtouch;
        struct xenkbd_page *page;
        int gref;
        int irq;
        struct xenbus_device *xbdev;
        char phys[32];
        /* current MT slot/contact ID we are injecting events in */
        int mtouch_cur_contact_id;
};

enum { KPARAM_X, KPARAM_Y, KPARAM_CNT };
static int ptr_size[KPARAM_CNT] = { XENFB_WIDTH, XENFB_HEIGHT };
module_param_array(ptr_size, int, NULL, 0444);
MODULE_PARM_DESC(ptr_size,
        "Pointing device width, height in pixels (default 800,600)");

static void xenkbd_remove(struct xenbus_device *);
static int xenkbd_connect_backend(struct xenbus_device *, struct xenkbd_info *);
static void xenkbd_disconnect_backend(struct xenkbd_info *);

/*
 * Note: if you need to send out events, see xenfb_do_update() for how
 * to do that.
 */

static void xenkbd_handle_motion_event(struct xenkbd_info *info,
                                       struct xenkbd_motion *motion)
{
        if (unlikely(!info->ptr))
                return;

        input_report_rel(info->ptr, REL_X, motion->rel_x);
        input_report_rel(info->ptr, REL_Y, motion->rel_y);
        if (motion->rel_z)
                input_report_rel(info->ptr, REL_WHEEL, -motion->rel_z);
        input_sync(info->ptr);
}

static void xenkbd_handle_position_event(struct xenkbd_info *info,
                                         struct xenkbd_position *pos)
{
        if (unlikely(!info->ptr))
                return;

        input_report_abs(info->ptr, ABS_X, pos->abs_x);
        input_report_abs(info->ptr, ABS_Y, pos->abs_y);
        if (pos->rel_z)
                input_report_rel(info->ptr, REL_WHEEL, -pos->rel_z);
        input_sync(info->ptr);
}

static void xenkbd_handle_key_event(struct xenkbd_info *info,
                                    struct xenkbd_key *key)
{
        struct input_dev *dev;
        int value = key->pressed;

        if (test_bit(key->keycode, info->ptr->keybit)) {
                dev = info->ptr;
        } else if (test_bit(key->keycode, info->kbd->keybit)) {
                dev = info->kbd;
                if (key->pressed && test_bit(key->keycode, info->kbd->key))
                        value = 2; /* Mark as autorepeat */
        } else {
                pr_warn("unhandled keycode 0x%x\n", key->keycode);
                return;
        }

        if (unlikely(!dev))
                return;

        input_event(dev, EV_KEY, key->keycode, value);
        input_sync(dev);
}

static void xenkbd_handle_mt_event(struct xenkbd_info *info,
                                   struct xenkbd_mtouch *mtouch)
{
        if (unlikely(!info->mtouch))
                return;

        if (mtouch->contact_id != info->mtouch_cur_contact_id) {
                info->mtouch_cur_contact_id = mtouch->contact_id;
                input_mt_slot(info->mtouch, mtouch->contact_id);
        }

        switch (mtouch->event_type) {
        case XENKBD_MT_EV_DOWN:
                input_mt_report_slot_state(info->mtouch, MT_TOOL_FINGER, true);
                fallthrough;

        case XENKBD_MT_EV_MOTION:
                input_report_abs(info->mtouch, ABS_MT_POSITION_X,
                                 mtouch->u.pos.abs_x);
                input_report_abs(info->mtouch, ABS_MT_POSITION_Y,
                                 mtouch->u.pos.abs_y);
                break;

        case XENKBD_MT_EV_SHAPE:
                input_report_abs(info->mtouch, ABS_MT_TOUCH_MAJOR,
                                 mtouch->u.shape.major);
                input_report_abs(info->mtouch, ABS_MT_TOUCH_MINOR,
                                 mtouch->u.shape.minor);
                break;

        case XENKBD_MT_EV_ORIENT:
                input_report_abs(info->mtouch, ABS_MT_ORIENTATION,
                                 mtouch->u.orientation);
                break;

        case XENKBD_MT_EV_UP:
                input_mt_report_slot_inactive(info->mtouch);
                break;

        case XENKBD_MT_EV_SYN:
                input_mt_sync_frame(info->mtouch);
                input_sync(info->mtouch);
                break;
        }
}

static void xenkbd_handle_event(struct xenkbd_info *info,
                                union xenkbd_in_event *event)
{
        switch (event->type) {
        case XENKBD_TYPE_MOTION:
                xenkbd_handle_motion_event(info, &event->motion);
                break;

        case XENKBD_TYPE_KEY:
                xenkbd_handle_key_event(info, &event->key);
                break;

        case XENKBD_TYPE_POS:
                xenkbd_handle_position_event(info, &event->pos);
                break;

        case XENKBD_TYPE_MTOUCH:
                xenkbd_handle_mt_event(info, &event->mtouch);
                break;
        }
}

static irqreturn_t input_handler(int rq, void *dev_id)
{
        struct xenkbd_info *info = dev_id;
        struct xenkbd_page *page = info->page;
        __u32 cons, prod;

        prod = page->in_prod;
        if (prod == page->in_cons)
                return IRQ_HANDLED;
        rmb();                  /* ensure we see ring contents up to prod */
        for (cons = page->in_cons; cons != prod; cons++)
                xenkbd_handle_event(info, &XENKBD_IN_RING_REF(page, cons));
        mb();                   /* ensure we got ring contents */
        page->in_cons = cons;
        notify_remote_via_irq(info->irq);

        return IRQ_HANDLED;
}

static int xenkbd_probe(struct xenbus_device *dev,
                                  const struct xenbus_device_id *id)
{
        int ret, i;
        bool with_mtouch, with_kbd, with_ptr;
        struct xenkbd_info *info;
        struct input_dev *kbd, *ptr, *mtouch;

        info = kzalloc_obj(*info);
        if (!info) {
                xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
                return -ENOMEM;
        }
        dev_set_drvdata(&dev->dev, info);
        info->xbdev = dev;
        info->irq = -1;
        info->gref = -1;
        snprintf(info->phys, sizeof(info->phys), "xenbus/%s", dev->nodename);

        info->page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
        if (!info->page)
                goto error_nomem;

        /*
         * The below are reverse logic, e.g. if the feature is set, then
         * do not expose the corresponding virtual device.
         */
        with_kbd = !xenbus_read_unsigned(dev->otherend,
                                         XENKBD_FIELD_FEAT_DSBL_KEYBRD, 0);

        with_ptr = !xenbus_read_unsigned(dev->otherend,
                                         XENKBD_FIELD_FEAT_DSBL_POINTER, 0);

        /* Direct logic: if set, then create multi-touch device. */
        with_mtouch = xenbus_read_unsigned(dev->otherend,
                                           XENKBD_FIELD_FEAT_MTOUCH, 0);
        if (with_mtouch) {
                ret = xenbus_write(XBT_NIL, dev->nodename,
                                   XENKBD_FIELD_REQ_MTOUCH, "1");
                if (ret) {
                        pr_warn("xenkbd: can't request multi-touch");
                        with_mtouch = 0;
                }
        }

        /* keyboard */
        if (with_kbd) {
                kbd = input_allocate_device();
                if (!kbd)
                        goto error_nomem;
                kbd->name = "Xen Virtual Keyboard";
                kbd->phys = info->phys;
                kbd->id.bustype = BUS_PCI;
                kbd->id.vendor = 0x5853;
                kbd->id.product = 0xffff;

                __set_bit(EV_KEY, kbd->evbit);
                for (i = KEY_ESC; i < KEY_UNKNOWN; i++)
                        __set_bit(i, kbd->keybit);
                for (i = KEY_OK; i < KEY_MAX; i++)
                        __set_bit(i, kbd->keybit);

                ret = input_register_device(kbd);
                if (ret) {
                        input_free_device(kbd);
                        xenbus_dev_fatal(dev, ret,
                                         "input_register_device(kbd)");
                        goto error;
                }
                info->kbd = kbd;
        }

        /* pointing device */
        if (with_ptr) {
                unsigned int abs;

                /* Set input abs params to match backend screen res */
                abs = xenbus_read_unsigned(dev->otherend,
                                           XENKBD_FIELD_FEAT_ABS_POINTER, 0);
                ptr_size[KPARAM_X] = xenbus_read_unsigned(dev->otherend,
                                                          XENKBD_FIELD_WIDTH,
                                                          ptr_size[KPARAM_X]);
                ptr_size[KPARAM_Y] = xenbus_read_unsigned(dev->otherend,
                                                          XENKBD_FIELD_HEIGHT,
                                                          ptr_size[KPARAM_Y]);
                if (abs) {
                        ret = xenbus_write(XBT_NIL, dev->nodename,
                                           XENKBD_FIELD_REQ_ABS_POINTER, "1");
                        if (ret) {
                                pr_warn("xenkbd: can't request abs-pointer\n");
                                abs = 0;
                        }
                }

                ptr = input_allocate_device();
                if (!ptr)
                        goto error_nomem;
                ptr->name = "Xen Virtual Pointer";
                ptr->phys = info->phys;
                ptr->id.bustype = BUS_PCI;
                ptr->id.vendor = 0x5853;
                ptr->id.product = 0xfffe;

                if (abs) {
                        __set_bit(EV_ABS, ptr->evbit);
                        input_set_abs_params(ptr, ABS_X, 0,
                                             ptr_size[KPARAM_X], 0, 0);
                        input_set_abs_params(ptr, ABS_Y, 0,
                                             ptr_size[KPARAM_Y], 0, 0);
                } else {
                        input_set_capability(ptr, EV_REL, REL_X);
                        input_set_capability(ptr, EV_REL, REL_Y);
                }
                input_set_capability(ptr, EV_REL, REL_WHEEL);

                __set_bit(EV_KEY, ptr->evbit);
                for (i = BTN_LEFT; i <= BTN_TASK; i++)
                        __set_bit(i, ptr->keybit);

                ret = input_register_device(ptr);
                if (ret) {
                        input_free_device(ptr);
                        xenbus_dev_fatal(dev, ret,
                                         "input_register_device(ptr)");
                        goto error;
                }
                info->ptr = ptr;
        }

        /* multi-touch device */
        if (with_mtouch) {
                int num_cont, width, height;

                mtouch = input_allocate_device();
                if (!mtouch)
                        goto error_nomem;

                num_cont = xenbus_read_unsigned(info->xbdev->otherend,
                                                XENKBD_FIELD_MT_NUM_CONTACTS,
                                                1);
                width = xenbus_read_unsigned(info->xbdev->otherend,
                                             XENKBD_FIELD_MT_WIDTH,
                                             XENFB_WIDTH);
                height = xenbus_read_unsigned(info->xbdev->otherend,
                                              XENKBD_FIELD_MT_HEIGHT,
                                              XENFB_HEIGHT);

                mtouch->name = "Xen Virtual Multi-touch";
                mtouch->phys = info->phys;
                mtouch->id.bustype = BUS_PCI;
                mtouch->id.vendor = 0x5853;
                mtouch->id.product = 0xfffd;

                input_set_abs_params(mtouch, ABS_MT_TOUCH_MAJOR,
                                     0, 255, 0, 0);
                input_set_abs_params(mtouch, ABS_MT_POSITION_X,
                                     0, width, 0, 0);
                input_set_abs_params(mtouch, ABS_MT_POSITION_Y,
                                     0, height, 0, 0);

                ret = input_mt_init_slots(mtouch, num_cont, INPUT_MT_DIRECT);
                if (ret) {
                        input_free_device(mtouch);
                        xenbus_dev_fatal(info->xbdev, ret,
                                         "input_mt_init_slots");
                        goto error;
                }

                ret = input_register_device(mtouch);
                if (ret) {
                        input_free_device(mtouch);
                        xenbus_dev_fatal(info->xbdev, ret,
                                         "input_register_device(mtouch)");
                        goto error;
                }
                info->mtouch_cur_contact_id = -1;
                info->mtouch = mtouch;
        }

        if (!(with_kbd || with_ptr || with_mtouch)) {
                ret = -ENXIO;
                goto error;
        }

        ret = xenkbd_connect_backend(dev, info);
        if (ret < 0)
                goto error;

        return 0;

 error_nomem:
        ret = -ENOMEM;
        xenbus_dev_fatal(dev, ret, "allocating device memory");
 error:
        xenkbd_remove(dev);
        return ret;
}

static int xenkbd_resume(struct xenbus_device *dev)
{
        struct xenkbd_info *info = dev_get_drvdata(&dev->dev);

        xenkbd_disconnect_backend(info);
        memset(info->page, 0, PAGE_SIZE);
        return xenkbd_connect_backend(dev, info);
}

static void xenkbd_remove(struct xenbus_device *dev)
{
        struct xenkbd_info *info = dev_get_drvdata(&dev->dev);

        xenkbd_disconnect_backend(info);
        if (info->kbd)
                input_unregister_device(info->kbd);
        if (info->ptr)
                input_unregister_device(info->ptr);
        if (info->mtouch)
                input_unregister_device(info->mtouch);
        free_page((unsigned long)info->page);
        kfree(info);
}

static int xenkbd_connect_backend(struct xenbus_device *dev,
                                  struct xenkbd_info *info)
{
        int ret, evtchn;
        struct xenbus_transaction xbt;

        ret = gnttab_grant_foreign_access(dev->otherend_id,
                                          virt_to_gfn(info->page), 0);
        if (ret < 0)
                return ret;
        info->gref = ret;

        ret = xenbus_alloc_evtchn(dev, &evtchn);
        if (ret)
                goto error_grant;
        ret = bind_evtchn_to_irqhandler(evtchn, input_handler,
                                        0, dev->devicetype, info);
        if (ret < 0) {
                xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler");
                goto error_evtchan;
        }
        info->irq = ret;

 again:
        ret = xenbus_transaction_start(&xbt);
        if (ret) {
                xenbus_dev_fatal(dev, ret, "starting transaction");
                goto error_irqh;
        }
        ret = xenbus_printf(xbt, dev->nodename, XENKBD_FIELD_RING_REF, "%lu",
                            virt_to_gfn(info->page));
        if (ret)
                goto error_xenbus;
        ret = xenbus_printf(xbt, dev->nodename, XENKBD_FIELD_RING_GREF,
                            "%u", info->gref);
        if (ret)
                goto error_xenbus;
        ret = xenbus_printf(xbt, dev->nodename, XENKBD_FIELD_EVT_CHANNEL, "%u",
                            evtchn);
        if (ret)
                goto error_xenbus;
        ret = xenbus_transaction_end(xbt, 0);
        if (ret) {
                if (ret == -EAGAIN)
                        goto again;
                xenbus_dev_fatal(dev, ret, "completing transaction");
                goto error_irqh;
        }

        xenbus_switch_state(dev, XenbusStateInitialised);
        return 0;

 error_xenbus:
        xenbus_transaction_end(xbt, 1);
        xenbus_dev_fatal(dev, ret, "writing xenstore");
 error_irqh:
        unbind_from_irqhandler(info->irq, info);
        info->irq = -1;
 error_evtchan:
        xenbus_free_evtchn(dev, evtchn);
 error_grant:
        gnttab_end_foreign_access(info->gref, NULL);
        info->gref = -1;
        return ret;
}

static void xenkbd_disconnect_backend(struct xenkbd_info *info)
{
        if (info->irq >= 0)
                unbind_from_irqhandler(info->irq, info);
        info->irq = -1;
        if (info->gref >= 0)
                gnttab_end_foreign_access(info->gref, NULL);
        info->gref = -1;
}

static void xenkbd_backend_changed(struct xenbus_device *dev,
                                   enum xenbus_state backend_state)
{
        switch (backend_state) {
        case XenbusStateInitialising:
        case XenbusStateInitialised:
        case XenbusStateReconfiguring:
        case XenbusStateReconfigured:
        case XenbusStateUnknown:
                break;

        case XenbusStateInitWait:
                xenbus_switch_state(dev, XenbusStateConnected);
                break;

        case XenbusStateConnected:
                /*
                 * Work around xenbus race condition: If backend goes
                 * through InitWait to Connected fast enough, we can
                 * get Connected twice here.
                 */
                if (dev->state != XenbusStateConnected)
                        xenbus_switch_state(dev, XenbusStateConnected);
                break;

        case XenbusStateClosed:
                if (dev->state == XenbusStateClosed)
                        break;
                fallthrough;    /* Missed the backend's CLOSING state */
        case XenbusStateClosing:
                xenbus_frontend_closed(dev);
                break;
        }
}

static const struct xenbus_device_id xenkbd_ids[] = {
        { XENKBD_DRIVER_NAME },
        { "" }
};

static struct xenbus_driver xenkbd_driver = {
        .ids = xenkbd_ids,
        .probe = xenkbd_probe,
        .remove = xenkbd_remove,
        .resume = xenkbd_resume,
        .otherend_changed = xenkbd_backend_changed,
        .not_essential = true,
};

static int __init xenkbd_init(void)
{
        if (!xen_domain())
                return -ENODEV;

        /* Nothing to do if running in dom0. */
        if (xen_initial_domain())
                return -ENODEV;

        if (!xen_has_pv_devices())
                return -ENODEV;

        return xenbus_register_frontend(&xenkbd_driver);
}

static void __exit xenkbd_cleanup(void)
{
        xenbus_unregister_driver(&xenkbd_driver);
}

module_init(xenkbd_init);
module_exit(xenkbd_cleanup);

MODULE_DESCRIPTION("Xen virtual keyboard/pointer device frontend");
MODULE_LICENSE("GPL");
MODULE_ALIAS("xen:" XENKBD_DRIVER_NAME);