// SPDX-License-Identifier: GPL-2.0-only /* * arch/arm/common/dmabounce.c * * Special dma_{map/unmap/dma_sync}_* routines for systems that have * limited DMA windows. These functions utilize bounce buffers to * copy data to/from buffers located outside the DMA region. This * only works for systems in which DMA memory is at the bottom of * RAM, the remainder of memory is at the top and the DMA memory * can be marked as ZONE_DMA. Anything beyond that such as discontiguous * DMA windows will require custom implementations that reserve memory * areas at early bootup. * * Original version by Brad Parker (brad@heeltoe.com) * Re-written by Christopher Hoover <ch@murgatroid.com> * Made generic by Deepak Saxena <dsaxena@plexity.net> * * Copyright (C) 2002 Hewlett Packard Company. * Copyright (C) 2004 MontaVista Software, Inc. */ #include <linux/module.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/page-flags.h> #include <linux/device.h> #include <linux/dma-mapping.h> #include <linux/dmapool.h> #include <linux/list.h> #include <linux/scatterlist.h> #include <asm/cacheflush.h> #include <asm/dma-iommu.h> #undef STATS #ifdef STATS #define DO_STATS(X) do { X ; } while (0) #else #define DO_STATS(X) do { } while (0) #endif /* ************************************************** */ struct safe_buffer { struct list_head node; /* original request */ void *ptr; size_t size; int direction; /* safe buffer info */ struct dmabounce_pool *pool; void *safe; dma_addr_t safe_dma_addr; }; struct dmabounce_pool { unsigned long size; struct dma_pool *pool; #ifdef STATS unsigned long allocs; #endif }; struct dmabounce_device_info { struct device *dev; struct list_head safe_buffers; #ifdef STATS unsigned long total_allocs; unsigned long map_op_count; unsigned long bounce_count; int attr_res; #endif struct dmabounce_pool small; struct dmabounce_pool large; rwlock_t lock; int (*needs_bounce)(struct device *, dma_addr_t, size_t); }; #ifdef STATS static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr, char *buf) { struct dmabounce_device_info *device_info = dev->archdata.dmabounce; return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n", device_info->small.allocs, device_info->large.allocs, device_info->total_allocs - device_info->small.allocs - device_info->large.allocs, device_info->total_allocs, device_info->map_op_count, device_info->bounce_count); } static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL); #endif /* allocate a 'safe' buffer and keep track of it */ static inline struct safe_buffer * alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr, size_t size, enum dma_data_direction dir) { struct safe_buffer *buf; struct dmabounce_pool *pool; struct device *dev = device_info->dev; unsigned long flags; dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n", __func__, ptr, size, dir); if (size <= device_info->small.size) { pool = &device_info->small; } else if (size <= device_info->large.size) { pool = &device_info->large; } else { pool = NULL; } buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC); if (buf == NULL) { dev_warn(dev, "%s: kmalloc failed\n", __func__); return NULL; } buf->ptr = ptr; buf->size = size; buf->direction = dir; buf->pool = pool; if (pool) { buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC, &buf->safe_dma_addr); } else { buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr, GFP_ATOMIC); } if (buf->safe == NULL) { dev_warn(dev, "%s: could not alloc dma memory (size=%d)\n", __func__, size); kfree(buf); return NULL; } #ifdef STATS if (pool) pool->allocs++; device_info->total_allocs++; #endif write_lock_irqsave(&device_info->lock, flags); list_add(&buf->node, &device_info->safe_buffers); write_unlock_irqrestore(&device_info->lock, flags); return buf; } /* determine if a buffer is from our "safe" pool */ static inline struct safe_buffer * find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr) { struct safe_buffer *b, *rb = NULL; unsigned long flags; read_lock_irqsave(&device_info->lock, flags); list_for_each_entry(b, &device_info->safe_buffers, node) if (b->safe_dma_addr <= safe_dma_addr && b->safe_dma_addr + b->size > safe_dma_addr) { rb = b; break; } read_unlock_irqrestore(&device_info->lock, flags); return rb; } static inline void free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf) { unsigned long flags; dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf); write_lock_irqsave(&device_info->lock, flags); list_del(&buf->node); write_unlock_irqrestore(&device_info->lock, flags); if (buf->pool) dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr); else dma_free_coherent(device_info->dev, buf->size, buf->safe, buf->safe_dma_addr); kfree(buf); } /* ************************************************** */ static struct safe_buffer *find_safe_buffer_dev(struct device *dev, dma_addr_t dma_addr, const char *where) { if (!dev || !dev->archdata.dmabounce) return NULL; if (dma_mapping_error(dev, dma_addr)) { dev_err(dev, "Trying to %s invalid mapping\n", where); return NULL; } return find_safe_buffer(dev->archdata.dmabounce, dma_addr); } static int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size) { if (!dev || !dev->archdata.dmabounce) return 0; if (dev->dma_mask) { unsigned long limit, mask = *dev->dma_mask; limit = (mask + 1) & ~mask; if (limit && size > limit) { dev_err(dev, "DMA mapping too big (requested %#x " "mask %#Lx)\n", size, *dev->dma_mask); return -E2BIG; } /* Figure out if we need to bounce from the DMA mask. */ if ((dma_addr | (dma_addr + size - 1)) & ~mask) return 1; } return !!dev->archdata.dmabounce->needs_bounce(dev, dma_addr, size); } static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size, enum dma_data_direction dir, unsigned long attrs) { struct dmabounce_device_info *device_info = dev->archdata.dmabounce; struct safe_buffer *buf; if (device_info) DO_STATS ( device_info->map_op_count++ ); buf = alloc_safe_buffer(device_info, ptr, size, dir); if (buf == NULL) { dev_err(dev, "%s: unable to map unsafe buffer %p!\n", __func__, ptr); return DMA_MAPPING_ERROR; } dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n", __func__, buf->ptr, virt_to_dma(dev, buf->ptr), buf->safe, buf->safe_dma_addr); if ((dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) { dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n", __func__, ptr, buf->safe, size); memcpy(buf->safe, ptr, size); } return buf->safe_dma_addr; } static inline void unmap_single(struct device *dev, struct safe_buffer *buf, size_t size, enum dma_data_direction dir, unsigned long attrs) { BUG_ON(buf->size != size); BUG_ON(buf->direction != dir); dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n", __func__, buf->ptr, virt_to_dma(dev, buf->ptr), buf->safe, buf->safe_dma_addr); DO_STATS(dev->archdata.dmabounce->bounce_count++); if ((dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) { void *ptr = buf->ptr; dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n", __func__, buf->safe, ptr, size); memcpy(ptr, buf->safe, size); /* * Since we may have written to a page cache page, * we need to ensure that the data will be coherent * with user mappings. */ __cpuc_flush_dcache_area(ptr, size); } free_safe_buffer(dev->archdata.dmabounce, buf); } /* ************************************************** */ /* * see if a buffer address is in an 'unsafe' range. if it is * allocate a 'safe' buffer and copy the unsafe buffer into it. * substitute the safe buffer for the unsafe one. * (basically move the buffer from an unsafe area to a safe one) */ static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction dir, unsigned long attrs) { dma_addr_t dma_addr; int ret; dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n", __func__, page, offset, size, dir); dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset; ret = needs_bounce(dev, dma_addr, size); if (ret < 0) return DMA_MAPPING_ERROR; if (ret == 0) { arm_dma_ops.sync_single_for_device(dev, dma_addr, size, dir); return dma_addr; } if (PageHighMem(page)) { dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n"); return DMA_MAPPING_ERROR; } return map_single(dev, page_address(page) + offset, size, dir, attrs); } /* * see if a mapped address was really a "safe" buffer and if so, copy * the data from the safe buffer back to the unsafe buffer and free up * the safe buffer. (basically return things back to the way they * should be) */ static void dmabounce_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir, unsigned long attrs) { struct safe_buffer *buf; dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n", __func__, dma_addr, size, dir); buf = find_safe_buffer_dev(dev, dma_addr, __func__); if (!buf) { arm_dma_ops.sync_single_for_cpu(dev, dma_addr, size, dir); return; } unmap_single(dev, buf, size, dir, attrs); } static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr, size_t sz, enum dma_data_direction dir) { struct safe_buffer *buf; unsigned long off; dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n", __func__, addr, sz, dir); buf = find_safe_buffer_dev(dev, addr, __func__); if (!buf) return 1; off = addr - buf->safe_dma_addr; BUG_ON(buf->direction != dir); dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n", __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off, buf->safe, buf->safe_dma_addr); DO_STATS(dev->archdata.dmabounce->bounce_count++); if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) { dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n", __func__, buf->safe + off, buf->ptr + off, sz); memcpy(buf->ptr + off, buf->safe + off, sz); } return 0; } static void dmabounce_sync_for_cpu(struct device *dev, dma_addr_t handle, size_t size, enum dma_data_direction dir) { if (!__dmabounce_sync_for_cpu(dev, handle, size, dir)) return; arm_dma_ops.sync_single_for_cpu(dev, handle, size, dir); } static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr, size_t sz, enum dma_data_direction dir) { struct safe_buffer *buf; unsigned long off; dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n", __func__, addr, sz, dir); buf = find_safe_buffer_dev(dev, addr, __func__); if (!buf) return 1; off = addr - buf->safe_dma_addr; BUG_ON(buf->direction != dir); dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n", __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off, buf->safe, buf->safe_dma_addr); DO_STATS(dev->archdata.dmabounce->bounce_count++); if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) { dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n", __func__,buf->ptr + off, buf->safe + off, sz); memcpy(buf->safe + off, buf->ptr + off, sz); } return 0; } static void dmabounce_sync_for_device(struct device *dev, dma_addr_t handle, size_t size, enum dma_data_direction dir) { if (!__dmabounce_sync_for_device(dev, handle, size, dir)) return; arm_dma_ops.sync_single_for_device(dev, handle, size, dir); } static int dmabounce_dma_supported(struct device *dev, u64 dma_mask) { if (dev->archdata.dmabounce) return 0; return arm_dma_ops.dma_supported(dev, dma_mask); } static const struct dma_map_ops dmabounce_ops = { .alloc = arm_dma_alloc, .free = arm_dma_free, .mmap = arm_dma_mmap, .get_sgtable = arm_dma_get_sgtable, .map_page = dmabounce_map_page, .unmap_page = dmabounce_unmap_page, .sync_single_for_cpu = dmabounce_sync_for_cpu, .sync_single_for_device = dmabounce_sync_for_device, .map_sg = arm_dma_map_sg, .unmap_sg = arm_dma_unmap_sg, .sync_sg_for_cpu = arm_dma_sync_sg_for_cpu, .sync_sg_for_device = arm_dma_sync_sg_for_device, .dma_supported = dmabounce_dma_supported, }; static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev, const char *name, unsigned long size) { pool->size = size; DO_STATS(pool->allocs = 0); pool->pool = dma_pool_create(name, dev, size, 0 /* byte alignment */, 0 /* no page-crossing issues */); return pool->pool ? 0 : -ENOMEM; } int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size, unsigned long large_buffer_size, int (*needs_bounce_fn)(struct device *, dma_addr_t, size_t)) { struct dmabounce_device_info *device_info; int ret; device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC); if (!device_info) { dev_err(dev, "Could not allocated dmabounce_device_info\n"); return -ENOMEM; } ret = dmabounce_init_pool(&device_info->small, dev, "small_dmabounce_pool", small_buffer_size); if (ret) { dev_err(dev, "dmabounce: could not allocate DMA pool for %ld byte objects\n", small_buffer_size); goto err_free; } if (large_buffer_size) { ret = dmabounce_init_pool(&device_info->large, dev, "large_dmabounce_pool", large_buffer_size); if (ret) { dev_err(dev, "dmabounce: could not allocate DMA pool for %ld byte objects\n", large_buffer_size); goto err_destroy; } } device_info->dev = dev; INIT_LIST_HEAD(&device_info->safe_buffers); rwlock_init(&device_info->lock); device_info->needs_bounce = needs_bounce_fn; #ifdef STATS device_info->total_allocs = 0; device_info->map_op_count = 0; device_info->bounce_count = 0; device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats); #endif dev->archdata.dmabounce = device_info; set_dma_ops(dev, &dmabounce_ops); dev_info(dev, "dmabounce: registered device\n"); return 0; err_destroy: dma_pool_destroy(device_info->small.pool); err_free: kfree(device_info); return ret; } EXPORT_SYMBOL(dmabounce_register_dev); void dmabounce_unregister_dev(struct device *dev) { struct dmabounce_device_info *device_info = dev->archdata.dmabounce; dev->archdata.dmabounce = NULL; set_dma_ops(dev, NULL); if (!device_info) { dev_warn(dev, "Never registered with dmabounce but attempting" "to unregister!\n"); return; } if (!list_empty(&device_info->safe_buffers)) { dev_err(dev, "Removing from dmabounce with pending buffers!\n"); BUG(); } if (device_info->small.pool) dma_pool_destroy(device_info->small.pool); if (device_info->large.pool) dma_pool_destroy(device_info->large.pool); #ifdef STATS if (device_info->attr_res == 0) device_remove_file(dev, &dev_attr_dmabounce_stats); #endif kfree(device_info); dev_info(dev, "dmabounce: device unregistered\n"); } EXPORT_SYMBOL(dmabounce_unregister_dev); MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>"); MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows"); MODULE_LICENSE("GPL");