/******************************************************************************
   * grant_table.h
   *
   * Two sets of functionality:
   * 1. Granting foreign access to our memory reservation.
   * 2. Accessing others' memory reservations via grant references.
   * (i.e., mechanisms for both sender and recipient of grant references)
   *
   * Copyright (c) 2004-2005, K A Fraser
   * Copyright (c) 2005, Christopher Clark
   *
   * 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 __ASM_GNTTAB_H__
  #define __ASM_GNTTAB_H__

  #include <asm/page.h>
  
  #include <xen/interface/xen.h>

  #include <xen/interface/grant_table.h>

  
  #include <asm/xen/hypervisor.h>

  #include <xen/features.h>

  #include <xen/page.h>

  #include <linux/mm_types.h>
  #include <linux/page-flags.h>

  #include <linux/kernel.h>

  #define GNTTAB_RESERVED_XENSTORE 1

  /* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */
  #define NR_GRANT_FRAMES 4
  
  struct gnttab_free_callback {
  	struct gnttab_free_callback *next;
  	void (*fn)(void *);
  	void *arg;
  	u16 count;
  };

  struct gntab_unmap_queue_data;
  
  typedef void (*gnttab_unmap_refs_done)(int result, struct gntab_unmap_queue_data *data);
  
  struct gntab_unmap_queue_data
  {
  	struct delayed_work	gnttab_work;
  	void *data;
  	gnttab_unmap_refs_done	done;
  	struct gnttab_unmap_grant_ref *unmap_ops;
  	struct gnttab_unmap_grant_ref *kunmap_ops;
  	struct page **pages;
  	unsigned int count;
  	unsigned int age;
  };

  int gnttab_init(void);

  int gnttab_suspend(void);
  int gnttab_resume(void);

  int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
  				int readonly);

  
  /*

   * End access through the given grant reference, iff the grant entry is no
   * longer in use.  Return 1 if the grant entry was freed, 0 if it is still in
   * use.
   */
  int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly);
  
  /*
   * Eventually end access through the given grant reference, and once that
   * access has been ended, free the given page too.  Access will be ended
   * immediately iff the grant entry is not in use, otherwise it will happen
   * some time later.  page may be 0, in which case no freeing will occur.
   */
  void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
  			       unsigned long page);
  
  int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn);
  
  unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref);
  unsigned long gnttab_end_foreign_transfer(grant_ref_t ref);
  
  int gnttab_query_foreign_access(grant_ref_t ref);
  
  /*
   * operations on reserved batches of grant references
   */
  int gnttab_alloc_grant_references(u16 count, grant_ref_t *pprivate_head);
  
  void gnttab_free_grant_reference(grant_ref_t ref);
  
  void gnttab_free_grant_references(grant_ref_t head);
  
  int gnttab_empty_grant_references(const grant_ref_t *pprivate_head);
  
  int gnttab_claim_grant_reference(grant_ref_t *pprivate_head);
  
  void gnttab_release_grant_reference(grant_ref_t *private_head,
  				    grant_ref_t release);
  
  void gnttab_request_free_callback(struct gnttab_free_callback *callback,
  				  void (*fn)(void *), void *arg, u16 count);
  void gnttab_cancel_free_callback(struct gnttab_free_callback *callback);
  
  void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
  				     unsigned long frame, int readonly);

  /* Give access to the first 4K of the page */
  static inline void gnttab_page_grant_foreign_access_ref_one(
  	grant_ref_t ref, domid_t domid,
  	struct page *page, int readonly)
  {
  	gnttab_grant_foreign_access_ref(ref, domid, xen_page_to_gfn(page),
  					readonly);
  }

  void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid,
  				       unsigned long pfn);

  static inline void
  gnttab_set_map_op(struct gnttab_map_grant_ref *map, phys_addr_t addr,
  		  uint32_t flags, grant_ref_t ref, domid_t domid)
  {
  	if (flags & GNTMAP_contains_pte)
  		map->host_addr = addr;
  	else if (xen_feature(XENFEAT_auto_translated_physmap))
  		map->host_addr = __pa(addr);
  	else
  		map->host_addr = addr;
  
  	map->flags = flags;
  	map->ref = ref;
  	map->dom = domid;
  }
  
  static inline void
  gnttab_set_unmap_op(struct gnttab_unmap_grant_ref *unmap, phys_addr_t addr,
  		    uint32_t flags, grant_handle_t handle)
  {
  	if (flags & GNTMAP_contains_pte)
  		unmap->host_addr = addr;
  	else if (xen_feature(XENFEAT_auto_translated_physmap))
  		unmap->host_addr = __pa(addr);
  	else
  		unmap->host_addr = addr;
  
  	unmap->handle = handle;
  	unmap->dev_bus_addr = 0;
  }

  int arch_gnttab_init(unsigned long nr_shared);

  int arch_gnttab_map_shared(xen_pfn_t *frames, unsigned long nr_gframes,

  			   unsigned long max_nr_gframes,

  			   void **__shared);

  void arch_gnttab_unmap(void *shared, unsigned long nr_gframes);

  struct grant_frames {
  	xen_pfn_t *pfn;
  	unsigned int count;
  	void *vaddr;
  };
  extern struct grant_frames xen_auto_xlat_grant_frames;

  unsigned int gnttab_max_grant_frames(void);

  int gnttab_setup_auto_xlat_frames(phys_addr_t addr);

  void gnttab_free_auto_xlat_frames(void);

  #define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr))

  int gnttab_alloc_pages(int nr_pages, struct page **pages);
  void gnttab_free_pages(int nr_pages, struct page **pages);

  int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,

  		    struct gnttab_map_grant_ref *kmap_ops,

  		    struct page **pages, unsigned int count);
  int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,

  		      struct gnttab_unmap_grant_ref *kunmap_ops,

  		      struct page **pages, unsigned int count);

  void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);

  int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item);

  /* Perform a batch of grant map/copy operations. Retry every batch slot
   * for which the hypervisor returns GNTST_eagain. This is typically due
   * to paged out target frames.
   *
   * Will retry for 1, 2, ... 255 ms, i.e. 256 times during 32 seconds.
   *
   * Return value in each iand every status field of the batch guaranteed
   * to not be GNTST_eagain.
   */
  void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count);
  void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count);

  
  struct xen_page_foreign {
  	domid_t domid;
  	grant_ref_t gref;
  };
  
  static inline struct xen_page_foreign *xen_page_foreign(struct page *page)
  {
  	if (!PageForeign(page))
  		return NULL;
  #if BITS_PER_LONG < 64
  	return (struct xen_page_foreign *)page->private;
  #else
  	BUILD_BUG_ON(sizeof(struct xen_page_foreign) > BITS_PER_LONG);
  	return (struct xen_page_foreign *)&page->private;
  #endif
  }

  /* Split Linux page in chunk of the size of the grant and call fn
   *
   * Parameters of fn:
   *	gfn: guest frame number
   *	offset: offset in the grant
   *	len: length of the data in the grant.
   *	data: internal information
   */
  typedef void (*xen_grant_fn_t)(unsigned long gfn, unsigned int offset,
  			       unsigned int len, void *data);
  
  void gnttab_foreach_grant_in_range(struct page *page,
  				   unsigned int offset,
  				   unsigned int len,
  				   xen_grant_fn_t fn,
  				   void *data);
  
  /* Helper to get to call fn only on the first "grant chunk" */
  static inline void gnttab_for_one_grant(struct page *page, unsigned int offset,
  					unsigned len, xen_grant_fn_t fn,
  					void *data)
  {
  	/* The first request is limited to the size of one grant */
  	len = min_t(unsigned int, XEN_PAGE_SIZE - (offset & ~XEN_PAGE_MASK),
  		    len);
  
  	gnttab_foreach_grant_in_range(page, offset, len, fn, data);
  }

  /* Get @nr_grefs grants from an array of page and call fn for each grant */
  void gnttab_foreach_grant(struct page **pages,
  			  unsigned int nr_grefs,
  			  xen_grant_fn_t fn,
  			  void *data);

  /* Get the number of grant in a specified region
   *
   * start: Offset from the beginning of the first page
   * len: total length of data (can cross multiple page)
   */
  static inline unsigned int gnttab_count_grant(unsigned int start,
  					      unsigned int len)
  {
  	return XEN_PFN_UP(xen_offset_in_page(start) + len);
  }

  #endif /* __ASM_GNTTAB_H__ */