/*
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License version 2
   * as published by the Free Software Foundation; or, when distributed
   * separately from the Linux kernel or incorporated into other
   * software packages, subject to the following license:
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this source file (the "Software"), to deal in the Software without
   * restriction, including without limitation the rights to use, copy, modify,
   * merge, publish, distribute, sublicense, and/or sell copies of the Software,
   * and to permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   * IN THE SOFTWARE.
   */

  #ifndef __XEN_BLKIF__BACKEND__COMMON_H__
  #define __XEN_BLKIF__BACKEND__COMMON_H__

  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/slab.h>
  #include <linux/blkdev.h>
  #include <linux/vmalloc.h>
  #include <linux/wait.h>

  #include <linux/io.h>

  #include <asm/setup.h>
  #include <asm/pgalloc.h>

  #include <asm/hypervisor.h>

  #include <xen/grant_table.h>

  #include <xen/xenbus.h>

  #include <xen/interface/io/ring.h>
  #include <xen/interface/io/blkif.h>
  #include <xen/interface/io/protocols.h>

  #define DRV_PFX "xen-blkback:"

  #define DPRINTK(fmt, args...)				\

  	pr_debug(DRV_PFX "(%s:%d) " fmt ".
  ",		\

  		 __func__, __LINE__, ##args)

  
  /* Not a real protocol.  Used to generate ring structs which contain
   * the elements common to all protocols only.  This way we get a
   * compiler-checkable way to use common struct elements, so we can
   * avoid using switch(protocol) in a number of places.  */
  struct blkif_common_request {
  	char dummy;
  };
  struct blkif_common_response {
  	char dummy;
  };

  struct blkif_x86_32_request_rw {

  	uint8_t        nr_segments;  /* number of segments                   */
  	blkif_vdev_t   handle;       /* only for read/write requests         */
  	uint64_t       id;           /* private guest value, echoed in resp  */

  	blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  	struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];

  } __attribute__((__packed__));

  
  struct blkif_x86_32_request_discard {

  	uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */

  	blkif_vdev_t   _pad1;        /* was "handle" for read/write requests */
  	uint64_t       id;           /* private guest value, echoed in resp  */

  	blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */

  	uint64_t       nr_sectors;
  } __attribute__((__packed__));

  struct blkif_x86_32_request {
  	uint8_t        operation;    /* BLKIF_OP_???                         */

  	union {
  		struct blkif_x86_32_request_rw rw;
  		struct blkif_x86_32_request_discard discard;
  	} u;

  } __attribute__((__packed__));
  
  /* i386 protocol version */
  #pragma pack(push, 4)

  struct blkif_x86_32_response {
  	uint64_t        id;              /* copied from request */
  	uint8_t         operation;       /* copied from request */
  	int16_t         status;          /* BLKIF_RSP_???       */
  };

  #pragma pack(pop)

  /* x86_64 protocol version */

  
  struct blkif_x86_64_request_rw {

  	uint8_t        nr_segments;  /* number of segments                   */
  	blkif_vdev_t   handle;       /* only for read/write requests         */
  	uint32_t       _pad1;        /* offsetof(blkif_reqest..,u.rw.id)==8  */
  	uint64_t       id;

  	blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  	struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];

  } __attribute__((__packed__));

  
  struct blkif_x86_64_request_discard {

  	uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */

  	blkif_vdev_t   _pad1;        /* was "handle" for read/write requests */
          uint32_t       _pad2;        /* offsetof(blkif_..,u.discard.id)==8   */
  	uint64_t       id;

  	blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */

  	uint64_t       nr_sectors;
  } __attribute__((__packed__));

  struct blkif_x86_64_request {
  	uint8_t        operation;    /* BLKIF_OP_???                         */

  	union {
  		struct blkif_x86_64_request_rw rw;
  		struct blkif_x86_64_request_discard discard;
  	} u;

  } __attribute__((__packed__));

  struct blkif_x86_64_response {
  	uint64_t       __attribute__((__aligned__(8))) id;
  	uint8_t         operation;       /* copied from request */
  	int16_t         status;          /* BLKIF_RSP_???       */
  };

  
  DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
  		  struct blkif_common_response);
  DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
  		  struct blkif_x86_32_response);
  DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
  		  struct blkif_x86_64_response);
  
  union blkif_back_rings {
  	struct blkif_back_ring        native;
  	struct blkif_common_back_ring common;
  	struct blkif_x86_32_back_ring x86_32;
  	struct blkif_x86_64_back_ring x86_64;
  };
  
  enum blkif_protocol {
  	BLKIF_PROTOCOL_NATIVE = 1,
  	BLKIF_PROTOCOL_X86_32 = 2,
  	BLKIF_PROTOCOL_X86_64 = 3,
  };

  enum blkif_backend_type {
  	BLKIF_BACKEND_PHY  = 1,
  	BLKIF_BACKEND_FILE = 2,
  };

  struct xen_vbd {

  	/* What the domain refers to this vbd as. */
  	blkif_vdev_t		handle;
  	/* Non-zero -> read-only */
  	unsigned char		readonly;
  	/* VDISK_xxx */
  	unsigned char		type;
  	/* phys device that this vbd maps to. */
  	u32			pdevice;
  	struct block_device	*bdev;
  	/* Cached size parameter. */
  	sector_t		size;
  	bool			flush_support;

  	bool			discard_secure;

  };
  
  struct backend_info;

  struct xen_blkif {

  	/* Unique identifier for this interface. */

  	domid_t			domid;
  	unsigned int		handle;

  	/* Physical parameters of the comms window. */

  	unsigned int		irq;

  	/* Comms information. */

  	enum blkif_protocol	blk_protocol;

  	enum blkif_backend_type blk_backend_type;

  	union blkif_back_rings	blk_rings;

  	void			*blk_ring;

  	/* The VBD attached to this interface. */

  	struct xen_vbd		vbd;

  	/* Back pointer to the backend_info. */

  	struct backend_info	*be;

  	/* Private fields. */

  	spinlock_t		blk_ring_lock;
  	atomic_t		refcnt;

  	wait_queue_head_t	wq;

  	/* for barrier (drain) requests */
  	struct completion	drain_complete;
  	atomic_t		drain;

  	/* One thread per one blkif. */

  	struct task_struct	*xenblkd;
  	unsigned int		waiting_reqs;

  
  	/* statistics */

  	unsigned long		st_print;
  	int			st_rd_req;
  	int			st_wr_req;
  	int			st_oo_req;
  	int			st_f_req;

  	int			st_ds_req;

  	int			st_rd_sect;
  	int			st_wr_sect;
  
  	wait_queue_head_t	waiting_to_free;

  };

  
  #define vbd_sz(_v)	((_v)->bdev->bd_part ? \
  			 (_v)->bdev->bd_part->nr_sects : \
  			  get_capacity((_v)->bdev->bd_disk))

  #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
  #define xen_blkif_put(_b)				\

  	do {						\
  		if (atomic_dec_and_test(&(_b)->refcnt))	\
  			wake_up(&(_b)->waiting_to_free);\
  	} while (0)

  struct phys_req {

  	unsigned short		dev;

  	blkif_sector_t		nr_sects;

  	struct block_device	*bdev;
  	blkif_sector_t		sector_number;

  };

  int xen_blkif_interface_init(void);

  int xen_blkif_xenbus_init(void);

  irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
  int xen_blkif_schedule(void *arg);

  int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
  			      struct backend_info *be, int state);

  int xen_blkbk_barrier(struct xenbus_transaction xbt,
  		      struct backend_info *be, int state);

  struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);

  static inline void blkif_get_x86_32_req(struct blkif_request *dst,

  					struct blkif_x86_32_request *src)
  {
  	int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
  	dst->operation = src->operation;

  	switch (src->operation) {
  	case BLKIF_OP_READ:
  	case BLKIF_OP_WRITE:
  	case BLKIF_OP_WRITE_BARRIER:
  	case BLKIF_OP_FLUSH_DISKCACHE:

  		dst->u.rw.nr_segments = src->u.rw.nr_segments;
  		dst->u.rw.handle = src->u.rw.handle;
  		dst->u.rw.id = src->u.rw.id;

  		dst->u.rw.sector_number = src->u.rw.sector_number;
  		barrier();

  		if (n > dst->u.rw.nr_segments)
  			n = dst->u.rw.nr_segments;

  		for (i = 0; i < n; i++)
  			dst->u.rw.seg[i] = src->u.rw.seg[i];
  		break;
  	case BLKIF_OP_DISCARD:

  		dst->u.discard.flag = src->u.discard.flag;

  		dst->u.discard.sector_number = src->u.discard.sector_number;
  		dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
  		break;
  	default:
  		break;
  	}

  }

  static inline void blkif_get_x86_64_req(struct blkif_request *dst,

  					struct blkif_x86_64_request *src)
  {
  	int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
  	dst->operation = src->operation;

  	switch (src->operation) {
  	case BLKIF_OP_READ:
  	case BLKIF_OP_WRITE:
  	case BLKIF_OP_WRITE_BARRIER:
  	case BLKIF_OP_FLUSH_DISKCACHE:

  		dst->u.rw.nr_segments = src->u.rw.nr_segments;
  		dst->u.rw.handle = src->u.rw.handle;
  		dst->u.rw.id = src->u.rw.id;

  		dst->u.rw.sector_number = src->u.rw.sector_number;
  		barrier();

  		if (n > dst->u.rw.nr_segments)
  			n = dst->u.rw.nr_segments;

  		for (i = 0; i < n; i++)
  			dst->u.rw.seg[i] = src->u.rw.seg[i];
  		break;
  	case BLKIF_OP_DISCARD:

  		dst->u.discard.flag = src->u.discard.flag;

  		dst->u.discard.sector_number = src->u.discard.sector_number;
  		dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
  		break;
  	default:
  		break;
  	}

  }

  #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */