/*	$NetBSD: virtioreg.h,v 1.11 2022/10/15 20:00:35 riastradh Exp $	*/

/*
 * 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.
 */

/*
 * Part of the file derived from `Virtio PCI Card Specification v0.8.6 DRAFT'
 * Appendix A.
 */
/* An interface for efficient virtio implementation.
 *
 * This header is BSD licensed so anyone can use the definitions
 * to implement compatible drivers/servers.
 *
 * Copyright 2007, 2009, IBM Corporation
 * 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.
 * 3. Neither the name of IBM nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``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 IBM OR CONTRIBUTORS 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.
 */


#ifndef KRX_DEV_VIRTIOREG_H
#define KRX_DEV_VIRTIOREG_H

#include <stdint.h>

#define __packed __attribute__((packed))
#define __BIT(__n)	(1ULL << (__n))

/* Virtio product id (all subsystems) */
#define VIRTIO_DEVICE_ID_NETWORK	 1
#define VIRTIO_DEVICE_ID_BLOCK		 2
#define VIRTIO_DEVICE_ID_CONSOLE	 3
#define VIRTIO_DEVICE_ID_ENTROPY	 4
#define VIRTIO_DEVICE_ID_BALLOON	 5
#define VIRTIO_DEVICE_ID_IOMEM		 6
#define VIRTIO_DEVICE_ID_RPMSG		 7
#define VIRTIO_DEVICE_ID_SCSI		 8
#define VIRTIO_DEVICE_ID_9P		 9
#define VIRTIO_DEVICE_ID_GPU		16

/* common device/guest features */
#define  VIRTIO_F_NOTIFY_ON_EMPTY		__BIT(24)
#define  VIRTIO_F_RING_INDIRECT_DESC		__BIT(28)
#define  VIRTIO_F_RING_EVENT_IDX		__BIT(29)
#define  VIRTIO_F_BAD_FEATURE			__BIT(30)
#define  VIRTIO_F_VERSION_1			__BIT(32)

/* common device status flags */
#define  VIRTIO_CONFIG_DEVICE_STATUS_RESET		  0
#define  VIRTIO_CONFIG_DEVICE_STATUS_ACK		  1
#define  VIRTIO_CONFIG_DEVICE_STATUS_DRIVER		  2
#define  VIRTIO_CONFIG_DEVICE_STATUS_DRIVER_OK		  4
#define  VIRTIO_CONFIG_DEVICE_STATUS_FEATURES_OK	  8
#define  VIRTIO_CONFIG_DEVICE_STATUS_DEVICE_NEEDS_RESET	 64
#define  VIRTIO_CONFIG_DEVICE_STATUS_FAILED		128

/* common ISR status flags */
#define  VIRTIO_CONFIG_ISR_QUEUE_INTERRUPT	1
#define  VIRTIO_CONFIG_ISR_CONFIG_CHANGE	2

/* common device/guest features */
#define VIRTIO_COMMON_FLAG_BITS			\
        "\177\020"				\
	"b\x20" "V1\0"				\
	"b\x1e" "BAD_FEATURE\0"			\
	"b\x1d" "EVENT_IDX\0"			\
	"b\x1c" "INDIRECT_DESC\0"		\
	"b\x18" "NOTIFY_ON_EMPTY\0"


/*
 * Virtqueue
 */

/* marks a buffer as continuing via the next field. */
#define VRING_DESC_F_NEXT       1

/* marks a buffer as write-only (otherwise read-only). */
#define VRING_DESC_F_WRITE      2

/* the buffer contains a list of buffer descriptors. */
#define VRING_DESC_F_INDIRECT	4


/*
 * The Host uses this in used->flags to advise the Guest: don't kick me when
 * you add a buffer.  It's unreliable, so it's simply an optimization.  Guest
 * will still kick if it's out of buffers.
 */
#define VRING_USED_F_NO_NOTIFY  1

/*
 * The Guest uses this in avail->flags to advise the Host: don't interrupt me
 * when you consume a buffer.  It's unreliable, so it's simply an
 * optimization.
 */
#define VRING_AVAIL_F_NO_INTERRUPT      1

/* Virtio ring descriptors: 16 bytes.
 * These can chain together via "next". */
struct vring_desc {
        /* Address (guest-physical). */
        uint64_t addr;
        /* Length. */
        uint32_t len;
        /* The flags as indicated above. */
        uint16_t flags;
        /* We chain unused descriptors via this, too */
        uint16_t next;
} __packed;

struct vring_avail {
        uint16_t flags;
        uint16_t idx;
        uint16_t ring[0];
	/* trailed by uint16_t used_event when VIRTIO_F_RING_EVENT_IDX */
} __packed;

/* u32 is used here for ids for padding reasons. */
struct vring_used_elem {
        /* Index of start of used descriptor chain. */
        uint32_t id;
        /* Total length of the descriptor chain which was written to. */
        uint32_t len;
} __packed;

struct vring_used {
        uint16_t flags;
        uint16_t idx;
        struct vring_used_elem ring[0];
	/* trailed by uint16_t avail_event when VIRTIO_F_RING_EVENT_IDX */
} __packed;

/* The standard layout for the ring is a continuous chunk of memory which
 * looks like this.  We assume num is a power of 2.
 *
 * struct vring {
 *      // The actual descriptors (16 bytes each)
 *      struct vring_desc desc[num];
 *
 *      // A ring of available descriptor heads with free-running index.
 *      __u16 avail_flags;
 *      __u16 avail_idx;
 *      __u16 available[num];
 *
 *      // Padding to the next align boundary.
 *      char pad[];
 *
 *      // A ring of used descriptor heads with free-running index.
 *      __u16 used_flags;
 *      __u16 used_idx;
 *      struct vring_used_elem used[num];
 * };
 * Note: for virtio PCI, align is 4096.
 */

#define VIRTIO_PAGE_SIZE	(4096)

#endif /* KRX_DEV_VIRTIOREG_H */
