/*
 * 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(sizeof(*info), GFP_KERNEL);
	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);