/* $OpenBSD: viomb.c,v 1.7 2013/10/31 01:54:43 dlg Exp $	 */
/* $NetBSD: viomb.c,v 1.1 2011/10/30 12:12:21 hannken Exp $	 */
/*
 * Copyright (c) 2012 Talypov Dinar <dinar@i-nk.ru>
 * Copyright (c) 2010 Minoura Makoto.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/device.h>
#include <sys/task.h>
#include <sys/pool.h>
#include <uvm/uvm.h>
#include <dev/pci/pcidevs.h>
#include <dev/pci/pcivar.h>

#include <dev/pci/virtioreg.h>
#include <dev/pci/virtiovar.h>

#if VIRTIO_PAGE_SIZE!=PAGE_SIZE
#error non-4K page sizes are not supported yet
#endif

#define	DEVNAME(sc)	sc->sc_dev.dv_xname
#if VIRTIO_DEBUG
#define VIOMBDEBUG(sc, format, args...)	\
		do { printf("%s: " format, sc->sc_dev.dv_xname, ##args);} \
		while (0)
#else
#define VIOMBDEBUG(...)
#endif

/* flags used to specify kind of operation,
 * actually should be moved to virtiovar.h
 */
#define VRING_READ		0
#define VRING_WRITE		1

/* notify or don't notify */
#define VRING_NO_NOTIFY		0
#define VRING_NOTIFY		1

/* Configuration registers */
#define VIRTIO_BALLOON_CONFIG_NUM_PAGES	0	/* 32bit */
#define VIRTIO_BALLOON_CONFIG_ACTUAL	4	/* 32bit */

/* Feature bits */
#define VIRTIO_BALLOON_F_MUST_TELL_HOST (1<<0)
#define VIRTIO_BALLOON_F_STATS_VQ	(1<<1)

static const struct virtio_feature_name viomb_feature_names[] = {
	{VIRTIO_BALLOON_F_MUST_TELL_HOST, "TellHost"},
	{VIRTIO_BALLOON_F_STATS_VQ, "StatVQ"},
	{0, NULL}
};
#define PGS_PER_REQ		256	/* 1MB, 4KB/page */
#define VQ_INFLATE	0
#define VQ_DEFLATE	1

struct balloon_req {
	bus_dmamap_t	 bl_dmamap;
	struct pglist	 bl_pglist;
	int		 bl_nentries;
	u_int32_t	*bl_pages;
};

struct viomb_softc {
	struct device		sc_dev;
	struct virtio_softc	*sc_virtio;
	struct virtqueue	sc_vq[2];
	u_int32_t		sc_npages;
	u_int32_t		sc_actual;
	struct balloon_req	sc_req;
	struct taskq		*sc_taskq;
	struct task		sc_task;
	struct pglist		sc_balloon_pages;
};

int	viomb_match(struct device *, void *, void *);
void	viomb_attach(struct device *, struct device *, void *);
void	viomb_worker(void *, void *);
void	viomb_inflate(struct viomb_softc *);
void	viomb_deflate(struct viomb_softc *);
int	viomb_config_change(struct virtio_softc *);
void	viomb_read_config(struct viomb_softc *);
int	viomb_vq_dequeue(struct virtqueue *);
int	viomb_inflate_intr(struct virtqueue *);
int	viomb_deflate_intr(struct virtqueue *);

struct cfattach viomb_ca = {
	sizeof(struct viomb_softc), viomb_match, viomb_attach
};

struct cfdriver viomb_cd = {
	NULL, "viomb", DV_DULL
};

int
viomb_match(struct device *parent, void *match, void *aux)
{
	struct virtio_softc *va = aux;
	if (va->sc_childdevid == PCI_PRODUCT_VIRTIO_BALLOON)
		return (1);
	return (0);
}

void
viomb_attach(struct device *parent, struct device *self, void *aux)
{
	struct viomb_softc *sc = (struct viomb_softc *)self;
	struct virtio_softc *vsc = (struct virtio_softc *)parent;
	u_int32_t features;
	int i;

	if (vsc->sc_child != NULL) {
		printf("child already attached for %s; something wrong...\n",
		    parent->dv_xname);
		return;
	}

	/* fail on non-4K page size archs */
	if (VIRTIO_PAGE_SIZE != PAGE_SIZE){
		printf("non-4K page size arch found, needs %d, got %d\n",
		    VIRTIO_PAGE_SIZE, PAGE_SIZE);
		return;
	}

	sc->sc_virtio = vsc;
	vsc->sc_vqs = &sc->sc_vq[VQ_INFLATE];
	vsc->sc_nvqs = 0;
	vsc->sc_child = self;
	vsc->sc_ipl = IPL_BIO;
	vsc->sc_config_change = viomb_config_change;
	vsc->sc_intrhand = virtio_vq_intr;

	/* negotiate features */
	features = VIRTIO_F_RING_INDIRECT_DESC;
	features = virtio_negotiate_features(vsc, features,
					     viomb_feature_names);

	if ((virtio_alloc_vq(vsc, &sc->sc_vq[VQ_INFLATE], VQ_INFLATE,
	     sizeof(u_int32_t) * PGS_PER_REQ, 1, "inflate") != 0))
		goto err;
	vsc->sc_nvqs++;
	if ((virtio_alloc_vq(vsc, &sc->sc_vq[VQ_DEFLATE], VQ_DEFLATE,
	     sizeof(u_int32_t) * PGS_PER_REQ, 1, "deflate") != 0))
		goto err;
	vsc->sc_nvqs++;

	sc->sc_vq[VQ_INFLATE].vq_done = viomb_inflate_intr;
	sc->sc_vq[VQ_DEFLATE].vq_done = viomb_deflate_intr;
	virtio_start_vq_intr(vsc, &sc->sc_vq[VQ_INFLATE]);
	virtio_start_vq_intr(vsc, &sc->sc_vq[VQ_DEFLATE]);

	viomb_read_config(sc);
	TAILQ_INIT(&sc->sc_balloon_pages);

	if ((sc->sc_req.bl_pages = dma_alloc(sizeof(u_int32_t) * PGS_PER_REQ,
	    PR_NOWAIT|PR_ZERO)) == NULL) {
		printf("%s: Can't alloc DMA memory.\n", DEVNAME(sc));
		goto err;
	}
	if (bus_dmamap_create(vsc->sc_dmat, sizeof(u_int32_t) * PGS_PER_REQ,
			      1, sizeof(u_int32_t) * PGS_PER_REQ, 0,
			      BUS_DMA_NOWAIT, &sc->sc_req.bl_dmamap)) {
		printf("%s: dmamap creation failed.\n", DEVNAME(sc));
		goto err;
	}
	if (bus_dmamap_load(vsc->sc_dmat, sc->sc_req.bl_dmamap,
			    &sc->sc_req.bl_pages[0],
			    sizeof(uint32_t) * PGS_PER_REQ,
			    NULL, BUS_DMA_NOWAIT)) {
		printf("%s: dmamap load failed.\n", DEVNAME(sc));
		goto err_dmamap;
	}

	sc->sc_taskq = taskq_create("viomb", 1, IPL_BIO);
	if (sc->sc_taskq == NULL)
		goto err_dmamap;
	task_set(&sc->sc_task, viomb_worker, sc, NULL);

	printf("\n");
	return;
err_dmamap:
	bus_dmamap_destroy(vsc->sc_dmat, sc->sc_req.bl_dmamap);
err:
	if (sc->sc_req.bl_pages)
		dma_free(sc->sc_req.bl_pages, sizeof(u_int32_t) * PGS_PER_REQ);
	for (i = 0; i < vsc->sc_nvqs; i++)
		virtio_free_vq(vsc, &sc->sc_vq[i]);
	vsc->sc_nvqs = 0;
	vsc->sc_child = VIRTIO_CHILD_ERROR;
	return;
}

/*
 * Config change
 */
int
viomb_config_change(struct virtio_softc *vsc)
{
	struct viomb_softc *sc = (struct viomb_softc *)vsc->sc_child;

	task_add(sc->sc_taskq, &sc->sc_task);

	return (1);
}

void
viomb_worker(void *arg1, void *arg2)
{
	struct viomb_softc *sc = (struct viomb_softc *)arg1;
	int s;

	s = splbio();
	viomb_read_config(sc);
	if (sc->sc_npages > sc->sc_actual){
		VIOMBDEBUG(sc, "inflating balloon from %u to %u.\n",
			   sc->sc_actual, sc->sc_npages);
		viomb_inflate(sc);
		}
	else if (sc->sc_npages < sc->sc_actual){
		viomb_deflate(sc);
		VIOMBDEBUG(sc, "deflating balloon from %u to %u.\n",
			   sc->sc_actual, sc->sc_npages);
	}
	splx(s);
}

void
viomb_inflate(struct viomb_softc *sc)
{
	struct virtio_softc *vsc = (struct virtio_softc *)sc->sc_virtio;
	struct balloon_req *b;
	struct vm_page *p;
	struct virtqueue *vq = &sc->sc_vq[VQ_INFLATE];
	u_int32_t nvpages;
	int slot, error, i = 0;

	nvpages = sc->sc_npages - sc->sc_actual;
	if (nvpages > PGS_PER_REQ)
		nvpages = PGS_PER_REQ;
	b = &sc->sc_req;

	if ((error = uvm_pglistalloc(nvpages * PAGE_SIZE, 0,
				     dma_constraint.ucr_high,
				     0, 0, &b->bl_pglist, nvpages,
				     UVM_PLA_NOWAIT))) {
		printf("%s unable to allocate %u physmem pages,"
		    "error %d\n", DEVNAME(sc), nvpages, error);
		return;
	}

	b->bl_nentries = nvpages;
	TAILQ_FOREACH(p, &b->bl_pglist, pageq)
		b->bl_pages[i++] = p->phys_addr / VIRTIO_PAGE_SIZE;

	KASSERT(i == nvpages);

	if ((virtio_enqueue_prep(vq, &slot)) > 0) {
		printf("%s:virtio_enqueue_prep() vq_num %d\n",
		       DEVNAME(sc), vq->vq_num);
		goto err;
	}
	if (virtio_enqueue_reserve(vq, slot, 1)) {
		printf("%s:virtio_enqueue_reserve vq_num %d\n",
		       DEVNAME(sc), vq->vq_num);
		goto err;
	}
	bus_dmamap_sync(vsc->sc_dmat, b->bl_dmamap, 0,
			sizeof(u_int32_t) * nvpages, BUS_DMASYNC_PREWRITE);
	virtio_enqueue_p(vq, slot, b->bl_dmamap, 0,
			 sizeof(u_int32_t) * nvpages, VRING_READ);
	virtio_enqueue_commit(vsc, vq, slot, VRING_NOTIFY);
	return;
err:
	uvm_pglistfree(&b->bl_pglist);
	return;
}

void
viomb_deflate(struct viomb_softc *sc)
{
	struct virtio_softc *vsc = (struct virtio_softc *)sc->sc_virtio;
	struct balloon_req *b;
	struct vm_page *p;
	struct virtqueue *vq = &sc->sc_vq[VQ_DEFLATE];
	u_int64_t nvpages;
	int i, slot;

	nvpages = sc->sc_actual - sc->sc_npages;
	if (nvpages > PGS_PER_REQ)
		nvpages = PGS_PER_REQ;
	b = &sc->sc_req;
	b->bl_nentries = nvpages;

	TAILQ_INIT(&b->bl_pglist);
	for (i = 0; i < nvpages; i++) {
		p = TAILQ_FIRST(&sc->sc_balloon_pages);
		if (p == NULL){
		    b->bl_nentries = i - 1;
		    break;
		}
		TAILQ_REMOVE(&sc->sc_balloon_pages, p, pageq);
		TAILQ_INSERT_TAIL(&b->bl_pglist, p, pageq);
		b->bl_pages[i] = p->phys_addr / VIRTIO_PAGE_SIZE;
	}

	if (virtio_enqueue_prep(vq, &slot)) {
		printf("%s:virtio_get_slot(def) vq_num %d\n",
		       DEVNAME(sc), vq->vq_num);
		goto err;
	}
	if (virtio_enqueue_reserve(vq, slot, 1)) {
		printf("%s:virtio_enqueue_reserve() vq_num %d\n",
		       DEVNAME(sc), vq->vq_num);
		goto err;
	}
	bus_dmamap_sync(vsc->sc_dmat, b->bl_dmamap, 0,
		    sizeof(u_int32_t) * nvpages,
		    BUS_DMASYNC_PREWRITE);
	virtio_enqueue_p(vq, slot, b->bl_dmamap, 0,
			 sizeof(u_int32_t) * nvpages, VRING_READ);

	if (!(vsc->sc_features & VIRTIO_BALLOON_F_MUST_TELL_HOST))
		uvm_pglistfree(&b->bl_pglist);
	virtio_enqueue_commit(vsc, vq, slot, VRING_NOTIFY);
	return;
err:
	while ((p = TAILQ_LAST(&b->bl_pglist, pglist))) {
		TAILQ_REMOVE(&b->bl_pglist, p, pageq);
		TAILQ_INSERT_HEAD(&sc->sc_balloon_pages, p, pageq);
	}
	return;
}

void
viomb_read_config(struct viomb_softc *sc)
{
	struct virtio_softc *vsc = (struct virtio_softc *)sc->sc_virtio;
	u_int32_t reg;

	/* these values are explicitly specified as little-endian */
	reg = virtio_read_device_config_4(vsc, VIRTIO_BALLOON_CONFIG_NUM_PAGES);
	sc->sc_npages = letoh32(reg);
	reg = virtio_read_device_config_4(vsc, VIRTIO_BALLOON_CONFIG_ACTUAL);
	sc->sc_actual = letoh32(reg);
	VIOMBDEBUG(sc, "sc->sc_npages %u, sc->sc_actual %u\n",
		   sc->sc_npages, sc->sc_actual);
}

int
viomb_vq_dequeue(struct virtqueue *vq)
{
	struct virtio_softc *vsc = vq->vq_owner;
	struct viomb_softc *sc = (struct viomb_softc *)vsc->sc_child;
	int r, slot;

	r = virtio_dequeue(vsc, vq, &slot, NULL);
	if (r != 0) {
		printf("%s: dequeue failed, errno %d\n",
		       DEVNAME(sc), r);
		return(r);
	}
	virtio_dequeue_commit(vq, slot);
	return(0);
}

/*
 * interrupt handling for vq's
 */
int
viomb_inflate_intr(struct virtqueue *vq)
{
	struct virtio_softc *vsc = vq->vq_owner;
	struct viomb_softc *sc = (struct viomb_softc *)vsc->sc_child;
	struct balloon_req *b;
	struct vm_page *p;
	u_int64_t nvpages;

	if (viomb_vq_dequeue(vq))
		return(1);

	b = &sc->sc_req;
	nvpages = b->bl_nentries;
	bus_dmamap_sync(vsc->sc_dmat, b->bl_dmamap, 0,
			sizeof(u_int32_t) * nvpages,
			BUS_DMASYNC_POSTWRITE);
	while (!TAILQ_EMPTY(&b->bl_pglist)) {
		p = TAILQ_FIRST(&b->bl_pglist);
		TAILQ_REMOVE(&b->bl_pglist, p, pageq);
		TAILQ_INSERT_TAIL(&sc->sc_balloon_pages, p, pageq);
	}
	VIOMBDEBUG(sc, "updating sc->sc_actual from %u to %llu\n",
		   sc->sc_actual, sc->sc_actual + nvpages);
	virtio_write_device_config_4(vsc, VIRTIO_BALLOON_CONFIG_ACTUAL,
				     sc->sc_actual + nvpages);
	viomb_read_config(sc);

	/* if we have more work to do, add it to the task list */
	if (sc->sc_npages > sc->sc_actual)
		task_add(sc->sc_taskq, &sc->sc_task);

	return (1);
}

int
viomb_deflate_intr(struct virtqueue *vq)
{
	struct virtio_softc *vsc = vq->vq_owner;
	struct viomb_softc *sc = (struct viomb_softc *)vsc->sc_child;
	struct balloon_req *b;
	u_int64_t nvpages;

	if (viomb_vq_dequeue(vq))
		return(1);

	b = &sc->sc_req;
	nvpages = b->bl_nentries;
	bus_dmamap_sync(vsc->sc_dmat, b->bl_dmamap, 0,
			sizeof(u_int32_t) * nvpages,
			BUS_DMASYNC_POSTWRITE);

	if (vsc->sc_features & VIRTIO_BALLOON_F_MUST_TELL_HOST)
		uvm_pglistfree(&b->bl_pglist);

	VIOMBDEBUG(sc, "updating sc->sc_actual from %u to %llu\n",
		sc->sc_actual, sc->sc_actual - nvpages);
	virtio_write_device_config_4(vsc, VIRTIO_BALLOON_CONFIG_ACTUAL,
				     sc->sc_actual - nvpages);
	viomb_read_config(sc);

	/* if we have more work to do, add it to tasks list */
	if (sc->sc_npages < sc->sc_actual)
		task_add(sc->sc_taskq, &sc->sc_task);

	return(1);
}