// SPDX-License-Identifier: GPL-2.0-only /* * DMA Pool allocator * * Copyright 2001 David Brownell * Copyright 2007 Intel Corporation * Author: Matthew Wilcox <[email protected]> * * 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 across all pages. 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/export.h> #include <linux/mutex.h> #include <linux/poison.h> #include <linux/sched.h> #include <linux/sched/mm.h> #include <linux/slab.h> #include <linux/stat.h> #include <linux/spinlock.h> #include <linux/string.h> #include <linux/types.h> #include <linux/wait.h> #ifdef CONFIG_SLUB_DEBUG_ON #define DMAPOOL_DEBUG … #endif struct dma_block { … }; struct dma_pool { … }; struct dma_page { … }; static DEFINE_MUTEX(pools_lock); static DEFINE_MUTEX(pools_reg_lock); static ssize_t pools_show(struct device *dev, struct device_attribute *attr, char *buf) { … } static DEVICE_ATTR_RO(pools); #ifdef DMAPOOL_DEBUG static void pool_check_block(struct dma_pool *pool, struct dma_block *block, gfp_t mem_flags) { u8 *data = (void *)block; int i; for (i = sizeof(struct dma_block); i < pool->size; i++) { if (data[i] == POOL_POISON_FREED) continue; dev_err(pool->dev, "%s %s, %p (corrupted)\n", __func__, pool->name, block); /* * Dump the first 4 bytes even if they are not * POOL_POISON_FREED */ print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1, data, pool->size, 1); break; } if (!want_init_on_alloc(mem_flags)) memset(block, POOL_POISON_ALLOCATED, pool->size); } static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) { struct dma_page *page; list_for_each_entry(page, &pool->page_list, page_list) { if (dma < page->dma) continue; if ((dma - page->dma) < pool->allocation) return page; } return NULL; } static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma) { struct dma_block *block = pool->next_block; struct dma_page *page; page = pool_find_page(pool, dma); if (!page) { dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n", __func__, pool->name, vaddr, &dma); return true; } while (block) { if (block != vaddr) { block = block->next_block; continue; } dev_err(pool->dev, "%s %s, dma %pad already free\n", __func__, pool->name, &dma); return true; } memset(vaddr, POOL_POISON_FREED, pool->size); return false; } static void pool_init_page(struct dma_pool *pool, struct dma_page *page) { memset(page->vaddr, POOL_POISON_FREED, pool->allocation); } #else static void pool_check_block(struct dma_pool *pool, struct dma_block *block, gfp_t mem_flags) { … } static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma) { … } static void pool_init_page(struct dma_pool *pool, struct dma_page *page) { … } #endif static struct dma_block *pool_block_pop(struct dma_pool *pool) { … } static void pool_block_push(struct dma_pool *pool, struct dma_block *block, dma_addr_t dma) { … } /** * 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: not in_interrupt() * * 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. * * Return: a dma allocation pool with the requested characteristics, or * %NULL if one can't be created. */ struct dma_pool *dma_pool_create(const char *name, struct device *dev, size_t size, size_t align, size_t boundary) { … } EXPORT_SYMBOL(…); static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page) { … } static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags) { … } /** * 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) { … } EXPORT_SYMBOL(…); /** * 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 * * Return: 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /* * Managed DMA pool */ static void dmam_pool_release(struct device *dev, void *res) { … } static int dmam_pool_match(struct device *dev, void *res, void *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. * * Return: a managed dma allocation pool with the requested * characteristics, or %NULL if one can't be created. */ struct dma_pool *dmam_pool_create(const char *name, struct device *dev, size_t size, size_t align, size_t allocation) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…);
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