/* SPDX-License-Identifier: GPL-2.0-only */

  /*
   * include/linux/idr.h
   * 
   * 2002-10-18  written by Jim Houston jim.houston@ccur.com
   *	Copyright (C) 2002 by Concurrent Computer Corporation

   *
   * Small id to pointer translation service avoiding fixed sized
   * tables.
   */

  
  #ifndef __IDR_H__
  #define __IDR_H__

  #include <linux/radix-tree.h>
  #include <linux/gfp.h>

  #include <linux/percpu.h>

  
  struct idr {
  	struct radix_tree_root	idr_rt;

  	unsigned int		idr_base;

  	unsigned int		idr_next;
  };

  /*

   * The IDR API does not expose the tagging functionality of the radix tree
   * to users.  Use tag 0 to track whether a node has free space below it.

   */

  #define IDR_FREE	0

  /* Set the IDR flag and the IDR_FREE tag */

  #define IDR_RT_MARKER	(ROOT_IS_IDR | (__force gfp_t)			\
  					(1 << (ROOT_TAG_SHIFT + IDR_FREE)))

  #define IDR_INIT_BASE(name, base) {					\
  	.idr_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER),			\

  	.idr_base = (base),						\
  	.idr_next = 0,							\

  }

  /**

   * IDR_INIT() - Initialise an IDR.

   * @name: Name of IDR.

   *
   * A freshly-initialised IDR contains no IDs.
   */

  #define IDR_INIT(name)	IDR_INIT_BASE(name, 0)

  
  /**

   * DEFINE_IDR() - Define a statically-allocated IDR.
   * @name: Name of IDR.

   *
   * An IDR defined using this macro is ready for use with no additional
   * initialisation required.  It contains no IDs.
   */

  #define DEFINE_IDR(name)	struct idr name = IDR_INIT(name)

  
  /**

   * idr_get_cursor - Return the current position of the cyclic allocator
   * @idr: idr handle
   *
   * The value returned is the value that will be next returned from
   * idr_alloc_cyclic() if it is free (otherwise the search will start from
   * this position).
   */

  static inline unsigned int idr_get_cursor(const struct idr *idr)

  {

  	return READ_ONCE(idr->idr_next);

  }
  
  /**
   * idr_set_cursor - Set the current position of the cyclic allocator
   * @idr: idr handle
   * @val: new position
   *
   * The next call to idr_alloc_cyclic() will return @val if it is free
   * (otherwise the search will start from this position).
   */
  static inline void idr_set_cursor(struct idr *idr, unsigned int val)
  {

  	WRITE_ONCE(idr->idr_next, val);

  }
  
  /**

   * DOC: idr sync

   * idr synchronization (stolen from radix-tree.h)
   *
   * idr_find() is able to be called locklessly, using RCU. The caller must
   * ensure calls to this function are made within rcu_read_lock() regions.
   * Other readers (lock-free or otherwise) and modifications may be running
   * concurrently.
   *
   * It is still required that the caller manage the synchronization and
   * lifetimes of the items. So if RCU lock-free lookups are used, typically
   * this would mean that the items have their own locks, or are amenable to
   * lock-free access; and that the items are freed by RCU (or only freed after
   * having been deleted from the idr tree *and* a synchronize_rcu() grace
   * period).
   */

  #define idr_lock(idr)		xa_lock(&(idr)->idr_rt)
  #define idr_unlock(idr)		xa_unlock(&(idr)->idr_rt)
  #define idr_lock_bh(idr)	xa_lock_bh(&(idr)->idr_rt)
  #define idr_unlock_bh(idr)	xa_unlock_bh(&(idr)->idr_rt)
  #define idr_lock_irq(idr)	xa_lock_irq(&(idr)->idr_rt)
  #define idr_unlock_irq(idr)	xa_unlock_irq(&(idr)->idr_rt)
  #define idr_lock_irqsave(idr, flags) \
  				xa_lock_irqsave(&(idr)->idr_rt, flags)
  #define idr_unlock_irqrestore(idr, flags) \
  				xa_unlock_irqrestore(&(idr)->idr_rt, flags)

  void idr_preload(gfp_t gfp_mask);

  int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t);
  int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id,

  				unsigned long max, gfp_t);

  int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t);
  void *idr_remove(struct idr *, unsigned long id);
  void *idr_find(const struct idr *, unsigned long id);

  int idr_for_each(const struct idr *,

  		 int (*fn)(int id, void *p, void *data), void *data);

  void *idr_get_next(struct idr *, int *nextid);

  void *idr_get_next_ul(struct idr *, unsigned long *nextid);

  void *idr_replace(struct idr *, void *, unsigned long id);

  void idr_destroy(struct idr *);

  /**
   * idr_init_base() - Initialise an IDR.
   * @idr: IDR handle.
   * @base: The base value for the IDR.
   *
   * This variation of idr_init() creates an IDR which will allocate IDs
   * starting at %base.
   */
  static inline void idr_init_base(struct idr *idr, int base)

  {

  	INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
  	idr->idr_base = base;
  	idr->idr_next = 0;

  }

  /**
   * idr_init() - Initialise an IDR.
   * @idr: IDR handle.
   *
   * Initialise a dynamically allocated IDR.  To initialise a
   * statically allocated IDR, use DEFINE_IDR().
   */

  static inline void idr_init(struct idr *idr)
  {

  	idr_init_base(idr, 0);

  }

  /**
   * idr_is_empty() - Are there any IDs allocated?
   * @idr: IDR handle.
   *
   * Return: %true if any IDs have been allocated from this IDR.
   */

  static inline bool idr_is_empty(const struct idr *idr)
  {
  	return radix_tree_empty(&idr->idr_rt) &&
  		radix_tree_tagged(&idr->idr_rt, IDR_FREE);
  }

  /**

   * idr_preload_end - end preload section started with idr_preload()
   *
   * Each idr_preload() should be matched with an invocation of this
   * function.  See idr_preload() for details.
   */
  static inline void idr_preload_end(void)
  {

  	local_unlock(&radix_tree_preloads.lock);

  }
  
  /**

   * idr_for_each_entry() - Iterate over an IDR's elements of a given type.
   * @idr: IDR handle.
   * @entry: The type * to use as cursor
   * @id: Entry ID.

   *
   * @entry and @id do not need to be initialized before the loop, and

   * after normal termination @entry is left with the value NULL.  This

   * is convenient for a "not found" value.

   */

  #define idr_for_each_entry(idr, entry, id)			\

  	for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; id += 1U)

  /**

   * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type.
   * @idr: IDR handle.
   * @entry: The type * to use as cursor.

   * @tmp: A temporary placeholder for ID.

   * @id: Entry ID.
   *
   * @entry and @id do not need to be initialized before the loop, and
   * after normal termination @entry is left with the value NULL.  This
   * is convenient for a "not found" value.
   */

  #define idr_for_each_entry_ul(idr, entry, tmp, id)			\
  	for (tmp = 0, id = 0;						\
  	     tmp <= id && ((entry) = idr_get_next_ul(idr, &(id))) != NULL; \
  	     tmp = id, ++id)

  
  /**
   * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
   * @idr: IDR handle.
   * @entry: The type * to use as a cursor.
   * @id: Entry ID.

   *

   * Continue to iterate over entries, continuing after the current position.

   */

  #define idr_for_each_entry_continue(idr, entry, id)			\
  	for ((entry) = idr_get_next((idr), &(id));			\

  	     entry;							\

  	     ++id, (entry) = idr_get_next((idr), &(id)))

  /**
   * idr_for_each_entry_continue_ul() - Continue iteration over an IDR's elements of a given type
   * @idr: IDR handle.
   * @entry: The type * to use as a cursor.
   * @tmp: A temporary placeholder for ID.
   * @id: Entry ID.
   *
   * Continue to iterate over entries, continuing after the current position.
   */
  #define idr_for_each_entry_continue_ul(idr, entry, tmp, id)		\
  	for (tmp = id;							\
  	     tmp <= id && ((entry) = idr_get_next_ul(idr, &(id))) != NULL; \
  	     tmp = id, ++id)

  /*

   * IDA - ID Allocator, use when translation from id to pointer isn't necessary.

   */
  #define IDA_CHUNK_SIZE		128	/* 128 bytes per chunk */

  #define IDA_BITMAP_LONGS	(IDA_CHUNK_SIZE / sizeof(long))

  #define IDA_BITMAP_BITS 	(IDA_BITMAP_LONGS * sizeof(long) * 8)

  
  struct ida_bitmap {

  	unsigned long		bitmap[IDA_BITMAP_LONGS];
  };
  
  struct ida {

  	struct xarray xa;

  };

  #define IDA_INIT_FLAGS	(XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC)

  #define IDA_INIT(name)	{						\

  	.xa = XARRAY_INIT(name, IDA_INIT_FLAGS)				\

  }

  #define DEFINE_IDA(name)	struct ida name = IDA_INIT(name)

  int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
  void ida_free(struct ida *, unsigned int id);

  void ida_destroy(struct ida *ida);

  /**
   * ida_alloc() - Allocate an unused ID.
   * @ida: IDA handle.
   * @gfp: Memory allocation flags.
   *
   * Allocate an ID between 0 and %INT_MAX, inclusive.
   *

   * Context: Any context. It is safe to call this function without
   * locking in your code.

   * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
   * or %-ENOSPC if there are no free IDs.
   */
  static inline int ida_alloc(struct ida *ida, gfp_t gfp)
  {
  	return ida_alloc_range(ida, 0, ~0, gfp);
  }

  /**
   * ida_alloc_min() - Allocate an unused ID.
   * @ida: IDA handle.
   * @min: Lowest ID to allocate.
   * @gfp: Memory allocation flags.
   *
   * Allocate an ID between @min and %INT_MAX, inclusive.
   *

   * Context: Any context. It is safe to call this function without
   * locking in your code.

   * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
   * or %-ENOSPC if there are no free IDs.
   */
  static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp)

  {

  	return ida_alloc_range(ida, min, ~0, gfp);

  }

  /**

   * ida_alloc_max() - Allocate an unused ID.
   * @ida: IDA handle.
   * @max: Highest ID to allocate.
   * @gfp: Memory allocation flags.
   *
   * Allocate an ID between 0 and @max, inclusive.

   *

   * Context: Any context. It is safe to call this function without
   * locking in your code.

   * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
   * or %-ENOSPC if there are no free IDs.

   */

  static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)

  {

  	return ida_alloc_range(ida, 0, max, gfp);

  }

  static inline void ida_init(struct ida *ida)
  {

  	xa_init_flags(&ida->xa, IDA_INIT_FLAGS);

  }

  /*
   * ida_simple_get() and ida_simple_remove() are deprecated. Use
   * ida_alloc() and ida_free() instead respectively.
   */

  #define ida_simple_get(ida, start, end, gfp)	\
  			ida_alloc_range(ida, start, (end) - 1, gfp)
  #define ida_simple_remove(ida, id)	ida_free(ida, id)

  static inline bool ida_is_empty(const struct ida *ida)

  {

  	return xa_empty(&ida->xa);

  }

  #endif /* __IDR_H__ */