/* * 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. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * version 2 as published by the Free Software Foundation. */ #include <linux/module.h> #include <linux/init.h> #include <linux/slab.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> #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; }; #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) { 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 inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size, enum dma_data_direction dir) { struct dmabounce_device_info *device_info = dev->archdata.dmabounce; dma_addr_t dma_addr; int needs_bounce = 0; if (device_info) DO_STATS ( device_info->map_op_count++ ); dma_addr = virt_to_dma(dev, ptr); if (dev->dma_mask) { unsigned long mask = *dev->dma_mask; unsigned long limit; 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 ~0; } /* * Figure out if we need to bounce from the DMA mask. */ needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask; } if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) { struct safe_buffer *buf; buf = alloc_safe_buffer(device_info, ptr, size, dir); if (buf == 0) { dev_err(dev, "%s: unable to map unsafe buffer %p!\n", __func__, ptr); return 0; } dev_dbg(dev, "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n", __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr), buf->safe, (void *) buf->safe_dma_addr); if ((dir == DMA_TO_DEVICE) || (dir == DMA_BIDIRECTIONAL)) { dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n", __func__, ptr, buf->safe, size); memcpy(buf->safe, ptr, size); } ptr = buf->safe; dma_addr = buf->safe_dma_addr; } else { /* * We don't need to sync the DMA buffer since * it was allocated via the coherent allocators. */ dma_cache_maint(ptr, size, dir); } return dma_addr; } static inline void unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir) { struct dmabounce_device_info *device_info = dev->archdata.dmabounce; struct safe_buffer *buf = NULL; /* * Trying to unmap an invalid mapping */ if (dma_mapping_error(dma_addr)) { dev_err(dev, "Trying to unmap invalid mapping\n"); return; } if (device_info) buf = find_safe_buffer(device_info, dma_addr); if (buf) { BUG_ON(buf->size != size); dev_dbg(dev, "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n", __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr), buf->safe, (void *) buf->safe_dma_addr); DO_STATS ( device_info->bounce_count++ ); if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) { 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); /* * DMA buffers must have the same cache properties * as if they were really used for DMA - which means * data must be written back to RAM. Note that * we don't use dmac_flush_range() here for the * bidirectional case because we know the cache * lines will be coherent with the data written. */ dmac_clean_range(ptr, ptr + size); outer_clean_range(__pa(ptr), __pa(ptr) + size); } free_safe_buffer(device_info, buf); } } static inline void sync_single(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir) { struct dmabounce_device_info *device_info = dev->archdata.dmabounce; struct safe_buffer *buf = NULL; if (device_info) buf = find_safe_buffer(device_info, dma_addr); if (buf) { /* * Both of these checks from original code need to be * commented out b/c some drivers rely on the following: * * 1) Drivers may map a large chunk of memory into DMA space * but only sync a small portion of it. Good example is * allocating a large buffer, mapping it, and then * breaking it up into small descriptors. No point * in syncing the whole buffer if you only have to * touch one descriptor. * * 2) Buffers that are mapped as DMA_BIDIRECTIONAL are * usually only synced in one dir at a time. * * See drivers/net/eepro100.c for examples of both cases. * * -ds * * BUG_ON(buf->size != size); * BUG_ON(buf->direction != dir); */ dev_dbg(dev, "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n", __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr), buf->safe, (void *) buf->safe_dma_addr); DO_STATS ( device_info->bounce_count++ ); switch (dir) { case DMA_FROM_DEVICE: dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n", __func__, buf->safe, buf->ptr, size); memcpy(buf->ptr, buf->safe, size); break; case DMA_TO_DEVICE: dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n", __func__,buf->ptr, buf->safe, size); memcpy(buf->safe, buf->ptr, size); break; case DMA_BIDIRECTIONAL: BUG(); /* is this allowed? what does it mean? */ default: BUG(); } /* * No need to sync the safe buffer - it was allocated * via the coherent allocators. */ } else { dma_cache_maint(dma_to_virt(dev, dma_addr), size, dir); } } /* ************************************************** */ /* * 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) */ dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size, enum dma_data_direction dir) { dma_addr_t dma_addr; dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n", __func__, ptr, size, dir); BUG_ON(dir == DMA_NONE); dma_addr = map_single(dev, ptr, size, dir); return dma_addr; } /* * 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) */ void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir) { dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n", __func__, (void *) dma_addr, size, dir); BUG_ON(dir == DMA_NONE); unmap_single(dev, dma_addr, size, dir); } int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir) { int i; dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n", __func__, sg, nents, dir); BUG_ON(dir == DMA_NONE); for (i = 0; i < nents; i++, sg++) { struct page *page = sg_page(sg); unsigned int offset = sg->offset; unsigned int length = sg->length; void *ptr = page_address(page) + offset; sg->dma_address = map_single(dev, ptr, length, dir); } return nents; } void dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir) { int i; dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n", __func__, sg, nents, dir); BUG_ON(dir == DMA_NONE); for (i = 0; i < nents; i++, sg++) { dma_addr_t dma_addr = sg->dma_address; unsigned int length = sg->length; unmap_single(dev, dma_addr, length, dir); } } void dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir) { dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n", __func__, (void *) dma_addr, size, dir); sync_single(dev, dma_addr, size, dir); } void dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir) { dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n", __func__, (void *) dma_addr, size, dir); sync_single(dev, dma_addr, size, dir); } void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir) { int i; dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n", __func__, sg, nents, dir); BUG_ON(dir == DMA_NONE); for (i = 0; i < nents; i++, sg++) { dma_addr_t dma_addr = sg->dma_address; unsigned int length = sg->length; sync_single(dev, dma_addr, length, dir); } } void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir) { int i; dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n", __func__, sg, nents, dir); BUG_ON(dir == DMA_NONE); for (i = 0; i < nents; i++, sg++) { dma_addr_t dma_addr = sg->dma_address; unsigned int length = sg->length; sync_single(dev, dma_addr, length, dir); } } 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) { struct dmabounce_device_info *device_info; int ret; device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC); if (!device_info) { printk(KERN_ERR "Could not allocated dmabounce_device_info for %s", dev->bus_id); 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); #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; printk(KERN_INFO "dmabounce: registered device %s on %s bus\n", dev->bus_id, dev->bus->name); return 0; err_destroy: dma_pool_destroy(device_info->small.pool); err_free: kfree(device_info); return ret; } void dmabounce_unregister_dev(struct device *dev) { struct dmabounce_device_info *device_info = dev->archdata.dmabounce; dev->archdata.dmabounce = NULL; if (!device_info) { printk(KERN_WARNING "%s: Never registered with dmabounce but attempting" \ "to unregister!\n", dev->bus_id); return; } if (!list_empty(&device_info->safe_buffers)) { printk(KERN_ERR "%s: Removing from dmabounce with pending buffers!\n", dev->bus_id); 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); printk(KERN_INFO "dmabounce: device %s on %s bus unregistered\n", dev->bus_id, dev->bus->name); } EXPORT_SYMBOL(dma_map_single); EXPORT_SYMBOL(dma_unmap_single); EXPORT_SYMBOL(dma_map_sg); EXPORT_SYMBOL(dma_unmap_sg); EXPORT_SYMBOL(dma_sync_single_for_cpu); EXPORT_SYMBOL(dma_sync_single_for_device); EXPORT_SYMBOL(dma_sync_sg); EXPORT_SYMBOL(dmabounce_register_dev); 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");