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#include <linux/pci.h>

#include <linux/slab.h>

#include <linux/module.h>

/*

 * Pool allocator ... wraps the pci_alloc_consistent page allocator, so

 * small blocks are easily used by drivers for bus mastering controllers.

 * This should probably be sharing the guts of the slab allocator.

 */

struct pci_pool {       /* the pool */

        struct list_head        page_list;

        spinlock_t              lock;

        size_t                  blocks_per_page;

        size_t                  size;

        struct pci_dev          *dev;

        size_t                  allocation;

        char                    name [32];

        wait_queue_head_t       waitq;

        struct list_head        pools;

};

struct pci_page {       /* cacheable header for 'allocation' bytes */

        struct list_head        page_list;

        void                    *vaddr;

        dma_addr_t              dma;

        unsigned                in_use;

        unsigned long           bitmap [0];

};

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

#define POOL_POISON_FREED       0xa7    /* !inuse */

#define POOL_POISON_ALLOCATED   0xa9    /* !initted */

static DECLARE_MUTEX (pools_lock);

static ssize_t

show_pools (struct device *dev, char *buf)

{

        struct pci_dev          *pdev;

        unsigned                temp, size;

        char                    *next;

        struct list_head        *i, *j;

        pdev = container_of (dev, struct pci_dev, dev);

        next = buf;

        size = PAGE_SIZE;

        temp = snprintf (next, size, "poolinfo - 0.1\n");

        size -= temp;

        next += temp;

        down (&pools_lock);

        list_for_each (i, &pdev->pools) {

                struct pci_pool *pool;

                unsigned        pages = 0, blocks = 0;

                pool = list_entry (i, struct pci_pool, pools);

                list_for_each (j, &pool->page_list) {

                        struct pci_page *page;

                        page = list_entry (j, struct pci_page, page_list);

                        pages++;

                        blocks += page->in_use;

                }

                /* per-pool info, no real statistics yet */

                temp = snprintf (next, size, "%-16s %4u %4Zu %4Zu %2u\n",

                                pool->name,

                                blocks, pages * pool->blocks_per_page,

                                pool->size, pages);

                size -= temp;

                next += temp;

        }

        up (&pools_lock);

        return PAGE_SIZE - size;

}

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

/**

 * pci_pool_create - Creates a pool of pci consistent memory blocks, for dma.

 * @name: name of pool, for diagnostics

 * @pdev: pci 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)

 * Context: !in_interrupt()

 *

 * Returns a pci allocation pool with the requested characteristics, or

 * null if one can't be created.  Given one of these pools, pci_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 allocation is nonzero, objects returned from pci_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 pci_pool *

pci_pool_create (const char *name, struct pci_dev *pdev,

        size_t size, size_t align, size_t allocation)

{

        struct pci_pool         *retval;

        if (align == 0)

                align = 1;

        if (size == 0)

                return 0;

        else if (size < align)

                size = align;

        else if ((size % align) != 0) {

                size += align + 1;

                size &= ~(align - 1);

        }

        if (allocation == 0) {

                if (PAGE_SIZE < size)

                        allocation = size;

                else

                        allocation = PAGE_SIZE;

                // FIXME: round up for less fragmentation

        } else if (allocation < size)

                return 0;

        if (!(retval = kmalloc (sizeof *retval, SLAB_KERNEL)))

                return retval;

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

        retval->dev = pdev;

        INIT_LIST_HEAD (&retval->page_list);

        spin_lock_init (&retval->lock);

        retval->size = size;

        retval->allocation = allocation;

        retval->blocks_per_page = allocation / size;

        init_waitqueue_head (&retval->waitq);

        if (pdev) {

                down (&pools_lock);

                if (list_empty (&pdev->pools))

                        device_create_file (&pdev->dev, &dev_attr_pools);

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

                list_add (&retval->pools, &pdev->pools);

                up (&pools_lock);

        } else

                INIT_LIST_HEAD (&retval->pools);

        return retval;

}

static struct pci_page *

pool_alloc_page (struct pci_pool *pool, int mem_flags)

{

        struct pci_page *page;

        int             mapsize;

        mapsize = pool->blocks_per_page;

        mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;

        mapsize *= sizeof (long);

        page = (struct pci_page *) kmalloc (mapsize + sizeof *page, mem_flags);

        if (!page)

                return 0;

        page->vaddr = pci_alloc_consistent (pool->dev,

                                            pool->allocation,

                                            &page->dma);

        if (page->vaddr) {

                memset (page->bitmap, 0xff, mapsize);   // bit set == free

#ifdef  CONFIG_DEBUG_SLAB

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

#endif

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

                page->in_use = 0;

        } else {

                kfree (page);

                page = 0;

        }

        return page;

}

static inline int

is_page_busy (int blocks, unsigned long *bitmap)

{

        while (blocks > 0) {

                if (*bitmap++ != ~0UL)

                        return 1;

                blocks -= BITS_PER_LONG;

        }

        return 0;

}

static void

pool_free_page (struct pci_pool *pool, struct pci_page *page)

{

        dma_addr_t      dma = page->dma;

#ifdef  CONFIG_DEBUG_SLAB

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

#endif

        pci_free_consistent (pool->dev, pool->allocation, page->vaddr, dma);

        list_del (&page->page_list);

        kfree (page);

}

/**

 * pci_pool_destroy - destroys a pool of pci memory blocks.

 * @pool: pci 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

pci_pool_destroy (struct pci_pool *pool)

{

        down (&pools_lock);

        list_del (&pool->pools);

        if (pool->dev && list_empty (&pool->dev->pools))

                device_remove_file (&pool->dev->dev, &dev_attr_pools);

        up (&pools_lock);

        while (!list_empty (&pool->page_list)) {

                struct pci_page         *page;

                page = list_entry (pool->page_list.next,

                                struct pci_page, page_list);

                if (is_page_busy (pool->blocks_per_page, page->bitmap)) {

                        printk (KERN_ERR "pci_pool_destroy %s/%s, %p busy\n",

                                pool->dev ? pci_name(pool->dev) : NULL,

                                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);

}

/**

 * pci_pool_alloc - get a block of consistent memory

 * @pool: pci pool that will produce the block

 * @mem_flags: SLAB_KERNEL or SLAB_ATOMIC

 * @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 *

pci_pool_alloc (struct pci_pool *pool, int mem_flags, dma_addr_t *handle)

{

        unsigned long           flags;

        struct list_head        *entry;

        struct pci_page         *page;

        int                     map, block;

        size_t                  offset;

        void                    *retval;

restart:

        spin_lock_irqsave (&pool->lock, flags);

        list_for_each (entry, &pool->page_list) {

                int             i;

                page = list_entry (entry, struct pci_page, page_list);

                /* only cachable accesses here ... */

                for (map = 0, i = 0;

                                i < pool->blocks_per_page;

                                i += BITS_PER_LONG, map++) {

                        if (page->bitmap [map] == 0)

                                continue;

                        block = ffz (~ page->bitmap [map]);

                        if ((i + block) < pool->blocks_per_page) {

                                clear_bit (block, &page->bitmap [map]);

                                offset = (BITS_PER_LONG * map) + block;

                                offset *= pool->size;

                                goto ready;

                        }

                }

        }

        if (!(page = pool_alloc_page (pool, SLAB_ATOMIC))) {

                if (mem_flags == SLAB_KERNEL) {

                        DECLARE_WAITQUEUE (wait, current);

                        current->state = TASK_INTERRUPTIBLE;

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

                        spin_unlock_irqrestore (&pool->lock, flags);

                        schedule_timeout (POOL_TIMEOUT_JIFFIES);

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

                        goto restart;

                }

                retval = 0;

                goto done;

        }

        clear_bit (0, &page->bitmap [0]);

        offset = 0;

ready:

        page->in_use++;

        retval = offset + page->vaddr;

        *handle = offset + page->dma;

#ifdef  CONFIG_DEBUG_SLAB

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

#endif

done:

        spin_unlock_irqrestore (&pool->lock, flags);

        return retval;

}

static struct pci_page *

pool_find_page (struct pci_pool *pool, dma_addr_t dma)

{

        unsigned long           flags;

        struct list_head        *entry;

        struct pci_page         *page;

        spin_lock_irqsave (&pool->lock, flags);

        list_for_each (entry, &pool->page_list) {

                page = list_entry (entry, struct pci_page, page_list);

                if (dma < page->dma)

                        continue;

                if (dma < (page->dma + pool->allocation))

                        goto done;

        }

        page = 0;

done:

        spin_unlock_irqrestore (&pool->lock, flags);

        return page;

}

/**

 * pci_pool_free - put block back into pci pool

 * @pool: the pci 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

pci_pool_free (struct pci_pool *pool, void *vaddr, dma_addr_t dma)

{

        struct pci_page         *page;

        unsigned long           flags;

        int                     map, block;

        if ((page = pool_find_page (pool, dma)) == 0) {

                printk (KERN_ERR "pci_pool_free %s/%s, %p/%lx (bad dma)\n",

                        pool->dev ? pci_name(pool->dev) : NULL,

                        pool->name, vaddr, (unsigned long) dma);

                return;

        }

        block = dma - page->dma;

        block /= pool->size;

        map = block / BITS_PER_LONG;

        block %= BITS_PER_LONG;

#ifdef  CONFIG_DEBUG_SLAB

        if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {

                printk (KERN_ERR "pci_pool_free %s/%s, %p (bad vaddr)/%Lx\n",

                        pool->dev ? pci_name(pool->dev) : NULL,

                        pool->name, vaddr, (unsigned long long) dma);

                return;

        }

        if (page->bitmap [map] & (1UL << block)) {

                printk (KERN_ERR "pci_pool_free %s/%s, dma %Lx already free\n",

                        pool->dev ? pci_name(pool->dev) : NULL,

                        pool->name, (unsigned long long)dma);

                return;

        }

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

#endif

        spin_lock_irqsave (&pool->lock, flags);

        page->in_use--;

        set_bit (block, &page->bitmap [map]);

        if (waitqueue_active (&pool->waitq))

                wake_up (&pool->waitq);

        /*

         * Resist a temptation to do

         *    if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);

         * it is not interrupt safe. Better have empty pages hang around.

         */

        spin_unlock_irqrestore (&pool->lock, flags);

}

EXPORT_SYMBOL (pci_pool_create);

EXPORT_SYMBOL (pci_pool_destroy);

EXPORT_SYMBOL (pci_pool_alloc);

EXPORT_SYMBOL (pci_pool_free);