/*
 * Copyright (c) 2016, Citrix Systems, Inc.
 *
 * 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 the copyright holder 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 THE COPYRIGHT OWNER
 * 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 _LINUX_BLKTAP_H
#define _LINUX_BLKTAP_H

/*
 * Control
 */

#define BLKTAP_IOCTL_RESPOND        1
#define BLKTAP_IOCTL_ALLOC_TAP      200
#define BLKTAP_IOCTL_FREE_TAP       201
#define BLKTAP_IOCTL_CREATE_DEVICE  208
#define BLKTAP_IOCTL_REMOVE_DEVICE  207

struct blktap_info {
	unsigned int            ring_major;
	unsigned int            bdev_major;
	unsigned int            ring_minor;
};

struct blktap_device_info {
	unsigned long long      capacity;
	unsigned int            sector_size;
	unsigned int            physical_sector_size;
	unsigned long           flags;
	unsigned long           __rsvd[4];
};

#define BLKTAP_DEVICE_RO        0x00000001UL

/*
 * I/O ring
 */

#ifdef __KERNEL__
#include <unistd.h>
#define BLKTAP_PAGE_SIZE sysconf(_SC_PAGESIZE)

static inline unsigned long
rounddown_pow_of_two(unsigned long x)
{
        return (1UL << (flsl(x) - 1));
}
#define BLKTAP_RD32(_n) rounddown_pow_of_two(_n)
#endif

#define __BLKTAP_RING_SIZE(_sz)					\
	((unsigned int)						\
	 BLKTAP_RD32(((_sz) - offsetof(struct blktap_sring, entry)) /	\
		     sizeof(union blktap_ring_entry)))

typedef struct blktap_ring_request  blktap_ring_req_t;
typedef struct blktap_ring_response blktap_ring_rsp_t;

struct blktap_segment {
	uint32_t                __pad;
	uint8_t                 first_sect;
	uint8_t                 last_sect;
};

#define BLKTAP_OP_READ          0
#define BLKTAP_OP_WRITE         1

#define BLKTAP_SEGMENT_MAX      11

struct blktap_ring_request {
	uint8_t                 operation;
	uint8_t                 nr_segments;
	uint16_t                __pad;
	uint64_t                id;
	uint64_t                sector_number;
	struct blktap_segment   seg[BLKTAP_SEGMENT_MAX];
};

#define BLKTAP_RSP_EOPNOTSUPP  -2
#define BLKTAP_RSP_ERROR       -1
#define BLKTAP_RSP_OKAY         0

struct blktap_ring_response {
	uint64_t                id;
	uint8_t                 operation;
	int16_t                 status;
};

union blktap_ring_entry {
	struct blktap_ring_request  req;
	struct blktap_ring_response rsp;
};

struct blktap_sring {
	uint32_t req_prod;
	uint32_t __req_event;

	uint32_t rsp_prod;
	uint32_t __rsp_event;

	uint8_t  msg;
	uint8_t  __rsvd[47];

	union blktap_ring_entry entry[0];
};

/*
 * Ring messages + old ioctls (DEPRECATED)
 */

#define BLKTAP_RING_MESSAGE_CLOSE   3
#define BLKTAP_IOCTL_CREATE_DEVICE_COMPAT 202
#define BLKTAP_NAME_MAX 256

struct blktap2_params {
	char               name[BLKTAP_NAME_MAX];
	unsigned long long capacity;
	unsigned long      sector_size;
};

#endif /* _LINUX_BLKTAP_H */