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| /* |
| * 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 <ddk.h> |
| #include <linux/mutex.h> |
| #include <syscall.h> |
| |
| |
| struct dma_pool { /* the pool */ |
| struct list_head page_list; |
| struct mutex lock; |
| size_t size; |
| size_t allocation; |
| size_t boundary; |
| 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; |
| }; |
| |
| |
| static DEFINE_MUTEX(pools_lock); |
| |
| |
| /** |
| * 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); |
| |
| allocation = (allocation+0x7FFF) & ~0x7FFF; |
| |
| if (!boundary) { |
| boundary = allocation; |
| } else if ((boundary < size) || (boundary & (boundary - 1))) { |
| return NULL; |
| } |
| |
| retval = kmalloc(sizeof(*retval), GFP_KERNEL); |
| |
| if (!retval) |
| return retval; |
| |
| INIT_LIST_HEAD(&retval->page_list); |
| |
| // spin_lock_init(&retval->lock); |
| |
| retval->size = size; |
| retval->boundary = boundary; |
| retval->allocation = allocation; |
| |
| INIT_LIST_HEAD(&retval->pools); |
| |
| return retval; |
| } |
| |
| 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) |
| { |
| struct dma_page *page; |
| |
| page = malloc(sizeof(*page)); |
| if (!page) |
| return NULL; |
| page->vaddr = (void*)KernelAlloc(pool->allocation); |
| |
| dbgprintf("%s 0x%0x ",__FUNCTION__, page->vaddr); |
| |
| if (page->vaddr) |
| { |
| page->dma = GetPgAddr(page->vaddr); |
| |
| dbgprintf("dma 0x%0x\n", page->dma); |
| |
| pool_initialise_page(pool, page); |
| list_add(&page->page_list, &pool->page_list); |
| page->in_use = 0; |
| page->offset = 0; |
| } else { |
| free(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; |
| |
| KernelFree(page->vaddr); |
| list_del(&page->page_list); |
| free(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); |
| 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)) |
| { |
| printk(KERN_ERR "dma_pool_destroy %p busy\n", |
| page->vaddr); |
| /* leak the still-in-use consistent memory */ |
| list_del(&page->page_list); |
| kfree(page); |
| } else |
| pool_free_page(pool, page); |
| } |
| |
| kfree(pool); |
| } |
| |
| |
| /** |
| * 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) |
| { |
| u32_t efl; |
| struct dma_page *page; |
| size_t offset; |
| void *retval; |
| |
| efl = safe_cli(); |
| restart: |
| list_for_each_entry(page, &pool->page_list, page_list) { |
| if (page->offset < pool->allocation) |
| goto ready; |
| } |
| page = pool_alloc_page(pool); |
| if (!page) |
| { |
| 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; |
| done: |
| safe_sti(efl); |
| return retval; |
| } |
| |
| |
| |
| static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) |
| { |
| struct dma_page *page; |
| u32_t efl; |
| |
| efl = safe_cli(); |
| |
| 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: |
| safe_sti(efl); |
| |
| 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; |
| |
| u32_t efl; |
| |
| page = pool_find_page(pool, dma); |
| if (!page) { |
| printk(KERN_ERR "dma_pool_free %p/%lx (bad dma)\n", |
| vaddr, (unsigned long)dma); |
| return; |
| } |
| |
| offset = vaddr - page->vaddr; |
| |
| efl = safe_cli(); |
| { |
| page->in_use--; |
| *(int *)vaddr = page->offset; |
| page->offset = offset; |
| /* |
| * Resist a temptation to do |
| * if (!is_page_busy(page)) pool_free_page(pool, page); |
| * Better have a few empty pages hang around. |
| */ |
| }safe_sti(efl); |
| } |
| |