/*
   * DMA Pool allocator
   *
   * Copyright 2001 David Brownell
   * Copyright 2007 Intel Corporation
   *   Author: Matthew Wilcox <willy@linux.intel.com>
   *
   * This software may be redistributed and/or modified under the terms of
   * the GNU General Public License ("GPL") version 2 as published by the
   * Free Software Foundation.
   *
   * This allocator returns small blocks of a given size which are DMA-able by
   * the given device.  It uses the dma_alloc_coherent page allocator to get
   * new pages, then splits them up into blocks of the required size.
   * Many older drivers still have their own code to do this.
   *
   * The current design of this allocator is fairly simple.  The pool is
   * represented by the 'struct dma_pool' which keeps a doubly-linked list of
   * allocated pages.  Each page in the page_list is split into blocks of at

   * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
   * list of free blocks within the page.  Used blocks aren't tracked, but we
   * keep a count of how many are currently allocated from each page.

   */

  
  #include <linux/device.h>

  #include <linux/dma-mapping.h>
  #include <linux/dmapool.h>

  #include <linux/kernel.h>
  #include <linux/list.h>

  #include <linux/module.h>

  #include <linux/mutex.h>

  #include <linux/poison.h>

  #include <linux/sched.h>

  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <linux/string.h>
  #include <linux/types.h>
  #include <linux/wait.h>

  #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
  #define DMAPOOL_DEBUG 1
  #endif

  struct dma_pool {		/* the pool */
  	struct list_head page_list;
  	spinlock_t lock;

  	size_t size;
  	struct device *dev;
  	size_t allocation;

  	size_t boundary;

  	char name[32];
  	wait_queue_head_t waitq;
  	struct list_head pools;

  };

  struct dma_page {		/* cacheable header for 'allocation' bytes */
  	struct list_head page_list;
  	void *vaddr;
  	dma_addr_t dma;

  	unsigned int in_use;
  	unsigned int offset;

  };
  
  #define	POOL_TIMEOUT_JIFFIES	((100 /* msec */ * HZ) / 1000)

  static DEFINE_MUTEX(pools_lock);

  
  static ssize_t

  show_pools(struct device *dev, struct device_attribute *attr, char *buf)

  {
  	unsigned temp;
  	unsigned size;
  	char *next;
  	struct dma_page *page;
  	struct dma_pool *pool;
  
  	next = buf;
  	size = PAGE_SIZE;
  
  	temp = scnprintf(next, size, "poolinfo - 0.1
  ");
  	size -= temp;
  	next += temp;

  	mutex_lock(&pools_lock);

  	list_for_each_entry(pool, &dev->dma_pools, pools) {
  		unsigned pages = 0;
  		unsigned blocks = 0;
  
  		list_for_each_entry(page, &pool->page_list, page_list) {
  			pages++;
  			blocks += page->in_use;
  		}
  
  		/* per-pool info, no real statistics yet */
  		temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u
  ",

  				 pool->name, blocks,
  				 pages * (pool->allocation / pool->size),

  				 pool->size, pages);

  		size -= temp;
  		next += temp;
  	}

  	mutex_unlock(&pools_lock);

  
  	return PAGE_SIZE - size;
  }

  
  static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);

  
  /**
   * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
   * @name: name of pool, for diagnostics
   * @dev: device that will be doing the DMA
   * @size: size of the blocks in this pool.
   * @align: alignment requirement for blocks; must be a power of two

   * @boundary: returned blocks won't cross this power of two boundary

   * Context: !in_interrupt()
   *
   * Returns a dma allocation pool with the requested characteristics, or
   * null if one can't be created.  Given one of these pools, dma_pool_alloc()
   * may be used to allocate memory.  Such memory will all have "consistent"
   * DMA mappings, accessible by the device and its driver without using
   * cache flushing primitives.  The actual size of blocks allocated may be
   * larger than requested because of alignment.
   *

   * If @boundary is nonzero, objects returned from dma_pool_alloc() won't

   * cross that size boundary.  This is useful for devices which have
   * addressing restrictions on individual DMA transfers, such as not crossing
   * boundaries of 4KBytes.
   */

  struct dma_pool *dma_pool_create(const char *name, struct device *dev,

  				 size_t size, size_t align, size_t boundary)

  {

  	struct dma_pool *retval;

  	size_t allocation;

  	if (align == 0) {

  		align = 1;

  	} else if (align & (align - 1)) {

  		return NULL;

  	}

  	if (size == 0) {

  		return NULL;

  	} else if (size < 4) {
  		size = 4;
  	}

  
  	if ((size % align) != 0)
  		size = ALIGN(size, align);

  	allocation = max_t(size_t, size, PAGE_SIZE);
  
  	if (!boundary) {
  		boundary = allocation;
  	} else if ((boundary < size) || (boundary & (boundary - 1))) {

  		return NULL;

  	}

  	retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
  	if (!retval)

  		return retval;

  	strlcpy(retval->name, name, sizeof(retval->name));

  
  	retval->dev = dev;

  	INIT_LIST_HEAD(&retval->page_list);
  	spin_lock_init(&retval->lock);

  	retval->size = size;

  	retval->boundary = boundary;

  	retval->allocation = allocation;

  	init_waitqueue_head(&retval->waitq);

  
  	if (dev) {

  		int ret;

  		mutex_lock(&pools_lock);

  		if (list_empty(&dev->dma_pools))
  			ret = device_create_file(dev, &dev_attr_pools);

  		else
  			ret = 0;

  		/* note:  not currently insisting "name" be unique */

  		if (!ret)

  			list_add(&retval->pools, &dev->dma_pools);

  		else {
  			kfree(retval);
  			retval = NULL;
  		}

  		mutex_unlock(&pools_lock);

  	} else

  		INIT_LIST_HEAD(&retval->pools);

  
  	return retval;
  }

  EXPORT_SYMBOL(dma_pool_create);

  static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
  {
  	unsigned int offset = 0;

  	unsigned int next_boundary = pool->boundary;

  
  	do {
  		unsigned int next = offset + pool->size;

  		if (unlikely((next + pool->size) >= next_boundary)) {
  			next = next_boundary;
  			next_boundary += pool->boundary;
  		}

  		*(int *)(page->vaddr + offset) = next;
  		offset = next;
  	} while (offset < pool->allocation);
  }

  static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)

  {

  	struct dma_page *page;

  	page = kmalloc(sizeof(*page), mem_flags);

  	if (!page)
  		return NULL;

  	page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,

  					 &page->dma, mem_flags);

  	if (page->vaddr) {

  #ifdef	DMAPOOL_DEBUG

  		memset(page->vaddr, POOL_POISON_FREED, pool->allocation);

  #endif

  		pool_initialise_page(pool, page);

  		list_add(&page->page_list, &pool->page_list);

  		page->in_use = 0;

  		page->offset = 0;

  	} else {

  		kfree(page);

  		page = NULL;
  	}
  	return page;
  }

  static inline int is_page_busy(struct dma_page *page)

  {

  	return page->in_use != 0;

  }

  static void pool_free_page(struct dma_pool *pool, struct dma_page *page)

  {

  	dma_addr_t dma = page->dma;

  #ifdef	DMAPOOL_DEBUG

  	memset(page->vaddr, POOL_POISON_FREED, pool->allocation);

  #endif

  	dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
  	list_del(&page->page_list);
  	kfree(page);

  }

  /**
   * dma_pool_destroy - destroys a pool of dma memory blocks.
   * @pool: dma pool that will be destroyed
   * Context: !in_interrupt()
   *
   * Caller guarantees that no more memory from the pool is in use,
   * and that nothing will try to use the pool after this call.
   */

  void dma_pool_destroy(struct dma_pool *pool)

  {

  	mutex_lock(&pools_lock);

  	list_del(&pool->pools);
  	if (pool->dev && list_empty(&pool->dev->dma_pools))
  		device_remove_file(pool->dev, &dev_attr_pools);

  	mutex_unlock(&pools_lock);

  	while (!list_empty(&pool->page_list)) {
  		struct dma_page *page;
  		page = list_entry(pool->page_list.next,
  				  struct dma_page, page_list);

  		if (is_page_busy(page)) {

  			if (pool->dev)

  				dev_err(pool->dev,
  					"dma_pool_destroy %s, %p busy
  ",

  					pool->name, page->vaddr);
  			else

  				printk(KERN_ERR
  				       "dma_pool_destroy %s, %p busy
  ",
  				       pool->name, page->vaddr);

  			/* leak the still-in-use consistent memory */

  			list_del(&page->page_list);
  			kfree(page);

  		} else

  			pool_free_page(pool, page);

  	}

  	kfree(pool);

  }

  EXPORT_SYMBOL(dma_pool_destroy);

  
  /**
   * dma_pool_alloc - get a block of consistent memory
   * @pool: dma pool that will produce the block
   * @mem_flags: GFP_* bitmask
   * @handle: pointer to dma address of block
   *
   * This returns the kernel virtual address of a currently unused block,
   * and reports its dma address through the handle.

   * If such a memory block can't be allocated, %NULL is returned.

   */

  void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
  		     dma_addr_t *handle)

  {

  	unsigned long flags;
  	struct dma_page *page;

  	size_t offset;
  	void *retval;

  	spin_lock_irqsave(&pool->lock, flags);

   restart:

  	list_for_each_entry(page, &pool->page_list, page_list) {

  		if (page->offset < pool->allocation)
  			goto ready;

  	}

  	page = pool_alloc_page(pool, GFP_ATOMIC);
  	if (!page) {

  		if (mem_flags & __GFP_WAIT) {

  			DECLARE_WAITQUEUE(wait, current);

  			__set_current_state(TASK_INTERRUPTIBLE);

  			__add_wait_queue(&pool->waitq, &wait);

  			spin_unlock_irqrestore(&pool->lock, flags);

  			schedule_timeout(POOL_TIMEOUT_JIFFIES);

  			spin_lock_irqsave(&pool->lock, flags);
  			__remove_wait_queue(&pool->waitq, &wait);

  			goto restart;
  		}
  		retval = NULL;
  		goto done;
  	}

   ready:

  	page->in_use++;

  	offset = page->offset;
  	page->offset = *(int *)(page->vaddr + offset);

  	retval = offset + page->vaddr;
  	*handle = offset + page->dma;

  #ifdef	DMAPOOL_DEBUG

  	memset(retval, POOL_POISON_ALLOCATED, pool->size);

  #endif

   done:
  	spin_unlock_irqrestore(&pool->lock, flags);

  	return retval;
  }

  EXPORT_SYMBOL(dma_pool_alloc);

  static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)

  {

  	unsigned long flags;
  	struct dma_page *page;

  	spin_lock_irqsave(&pool->lock, flags);

  	list_for_each_entry(page, &pool->page_list, page_list) {
  		if (dma < page->dma)
  			continue;
  		if (dma < (page->dma + pool->allocation))
  			goto done;
  	}
  	page = NULL;

   done:
  	spin_unlock_irqrestore(&pool->lock, flags);

  	return page;
  }

  /**
   * dma_pool_free - put block back into dma pool
   * @pool: the dma pool holding the block
   * @vaddr: virtual address of block
   * @dma: dma address of block
   *
   * Caller promises neither device nor driver will again touch this block
   * unless it is first re-allocated.
   */

  void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)

  {

  	struct dma_page *page;
  	unsigned long flags;

  	unsigned int offset;

  	page = pool_find_page(pool, dma);
  	if (!page) {

  		if (pool->dev)

  			dev_err(pool->dev,
  				"dma_pool_free %s, %p/%lx (bad dma)
  ",
  				pool->name, vaddr, (unsigned long)dma);

  		else

  			printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)
  ",
  			       pool->name, vaddr, (unsigned long)dma);

  		return;
  	}

  	offset = vaddr - page->vaddr;

  #ifdef	DMAPOOL_DEBUG

  	if ((dma - page->dma) != offset) {

  		if (pool->dev)

  			dev_err(pool->dev,
  				"dma_pool_free %s, %p (bad vaddr)/%Lx
  ",
  				pool->name, vaddr, (unsigned long long)dma);

  		else

  			printk(KERN_ERR
  			       "dma_pool_free %s, %p (bad vaddr)/%Lx
  ",
  			       pool->name, vaddr, (unsigned long long)dma);

  		return;
  	}

  	{
  		unsigned int chain = page->offset;
  		while (chain < pool->allocation) {
  			if (chain != offset) {
  				chain = *(int *)(page->vaddr + chain);
  				continue;
  			}
  			if (pool->dev)
  				dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
  					"already free
  ", pool->name,
  					(unsigned long long)dma);
  			else
  				printk(KERN_ERR "dma_pool_free %s, dma %Lx "
  					"already free
  ", pool->name,
  					(unsigned long long)dma);
  			return;
  		}

  	}

  	memset(vaddr, POOL_POISON_FREED, pool->size);

  #endif

  	spin_lock_irqsave(&pool->lock, flags);

  	page->in_use--;

  	*(int *)vaddr = page->offset;
  	page->offset = offset;

  	if (waitqueue_active(&pool->waitq))

  		wake_up_locked(&pool->waitq);

  	/*
  	 * Resist a temptation to do

  	 *    if (!is_page_busy(page)) pool_free_page(pool, page);

  	 * Better have a few empty pages hang around.
  	 */

  	spin_unlock_irqrestore(&pool->lock, flags);

  }

  EXPORT_SYMBOL(dma_pool_free);

  /*
   * Managed DMA pool
   */
  static void dmam_pool_release(struct device *dev, void *res)
  {
  	struct dma_pool *pool = *(struct dma_pool **)res;
  
  	dma_pool_destroy(pool);
  }
  
  static int dmam_pool_match(struct device *dev, void *res, void *match_data)
  {
  	return *(struct dma_pool **)res == match_data;
  }
  
  /**
   * dmam_pool_create - Managed dma_pool_create()
   * @name: name of pool, for diagnostics
   * @dev: device that will be doing the DMA
   * @size: size of the blocks in this pool.
   * @align: alignment requirement for blocks; must be a power of two
   * @allocation: returned blocks won't cross this boundary (or zero)
   *
   * Managed dma_pool_create().  DMA pool created with this function is
   * automatically destroyed on driver detach.
   */
  struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
  				  size_t size, size_t align, size_t allocation)
  {
  	struct dma_pool **ptr, *pool;
  
  	ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
  	if (!ptr)
  		return NULL;
  
  	pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
  	if (pool)
  		devres_add(dev, ptr);
  	else
  		devres_free(ptr);
  
  	return pool;
  }

  EXPORT_SYMBOL(dmam_pool_create);

  
  /**
   * dmam_pool_destroy - Managed dma_pool_destroy()
   * @pool: dma pool that will be destroyed
   *
   * Managed dma_pool_destroy().
   */
  void dmam_pool_destroy(struct dma_pool *pool)
  {
  	struct device *dev = pool->dev;
  
  	dma_pool_destroy(pool);
  	WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
  }

  EXPORT_SYMBOL(dmam_pool_destroy);