[ARM PATCH] 1815/1: Generic DMA buffer bouncing support for ARM targets

Patch from Deepak Saxena

Latest (and hopefully last :) patch for generic DMA buffer bouncing.

- Fixed SA1111 dma_needs_bounce
- Added check for out of bounds buffers.
- Made dmabounce.c directly implement dma_* API

Note that I didn't do the following:

#ifndef CONFIG_DMABOUNCE
inline implementations of all functions
#else
extern declarations
#endif

Instead I wrapped it individual in #ifndef/#else blocks to keep the
comments in the same area as function declarations.  IMHO this makes 
it easier for someone to go look at the comments if they need to know 
what a specific API does.

arch/arm/Kconfig

@@ -210,6 +210,11 @@ config FORCE_MAX_ZONEORDER
 	depends on SA1111
 	default "9"
 
+config DMABOUNCE
+	bool
+	depends on SA1111
+	default y
+
 source arch/arm/mm/Kconfig
 
 #  bool 'Use XScale PMU as timer source' CONFIG_XSCALE_PMU_TIMER

arch/arm/common/Makefile

@@ -5,6 +5,7 @@
 obj-y				+= platform.o
 obj-$(CONFIG_ARM_AMBA)		+= amba.o
 obj-$(CONFIG_ICST525)		+= icst525.o
-obj-$(CONFIG_SA1111)		+= sa1111.o sa1111-pcibuf.o
+obj-$(CONFIG_SA1111)		+= sa1111.o
 obj-$(CONFIG_PCI_HOST_PLX90X0)	+= plx90x0.o
 obj-$(CONFIG_PCI_HOST_VIA82C505) += via82c505.o
+obj-$(CONFIG_DMABOUNCE)		+= dmabounce.o

arch/arm/common/sa1111-pcibuf.c → arch/arm/common/dmabounce.c

 /*
- *  linux/arch/arm/mach-sa1100/sa1111-pcibuf.c
+ *  arch/arm/common/dmabounce.c
  *
- *  Special dma_{map/unmap/dma_sync}_* routines for SA-1111.
+ *  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 and the remainder of memory is at the top an the DMA memory
+ *  can be marked as ZONE_DMA. Anything beyond that such as discontigous
+ *  DMA windows will require custom implementations that reserve memory
+ *  areas at early bootup.
  *
- *  These functions utilize bouncer buffers to compensate for a bug in
- *  the SA-1111 hardware which don't allow DMA to/from addresses
- *  certain addresses above 1MB.
- *
- *  Re-written by Christopher Hoover <ch@murgatroid.com>
  *  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.
- * */
-
-//#define DEBUG
+ */
 
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
-#include <linux/list.h>
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmapool.h>
-#include <asm/hardware/sa1111.h>
+#include <linux/list.h>
 
-//#define STATS
+#undef DEBUG
+
+#undef STATS
 #ifdef STATS
 #define DO_STATS(X) do { X ; } while (0)
 #else
@@ -43,308 +47,315 @@ struct safe_buffer {
 	/* original request */
 	void		*ptr;
 	size_t		size;
-	enum dma_data_direction direction;
+	int		direction;
 
 	/* safe buffer info */
 	struct dma_pool *pool;
 	void		*safe;
 	dma_addr_t	safe_dma_addr;
-	struct device	*dev;
 };
 
-static LIST_HEAD(safe_buffers);
-
+struct dmabounce_device_info {
+	struct list_head node;
 
-#define SIZE_SMALL	1024
-#define SIZE_LARGE	(4*1024)
+	struct device *dev;
+	struct dma_pool *small_buffer_pool;
+	struct dma_pool *large_buffer_pool;
+	struct list_head safe_buffers;
+	unsigned long small_buffer_size, large_buffer_size;
+#ifdef STATS
+	unsigned long sbp_allocs;
+	unsigned long lbp_allocs;
+	unsigned long total_allocs;
+	unsigned long map_op_count;
+	unsigned long bounce_count;
+#endif
+};
 
-static struct dma_pool *small_buffer_pool, *large_buffer_pool;
+static LIST_HEAD(dmabounce_devs);
 
 #ifdef STATS
-static unsigned long sbp_allocs __initdata = 0;
-static unsigned long lbp_allocs __initdata = 0;
-static unsigned long total_allocs __initdata= 0;
-
-static void print_alloc_stats(void)
+static void print_alloc_stats(struct dmabounce_device_info *device_info)
 {
 	printk(KERN_INFO
-	       "sa1111_dmabuf: sbp: %lu, lbp: %lu, other: %lu, total: %lu\n",
-	       sbp_allocs, lbp_allocs,
-	       total_allocs - sbp_allocs - lbp_allocs, total_allocs);
+		"%s: dmabounce: sbp: %lu, lbp: %lu, other: %lu, total: %lu\n",
+		device_info->dev->bus_id,
+		device_info->sbp_allocs, device_info->lbp_allocs,
+		device_info->total_allocs - device_info->sbp_allocs -
+			device_info->lbp_allocs,
+		device_info->total_allocs);
 }
 #endif
 
-static int __init create_safe_buffer_pools(void)
+/* find the given device in the dmabounce device list */
+static inline struct dmabounce_device_info *
+find_dmabounce_dev(struct device *dev)
 {
-	small_buffer_pool = dma_pool_create("sa1111_small_dma_buffer",
-					    NULL, SIZE_SMALL,
-					    0 /* byte alignment */,
-					    0 /* no page-crossing issues */);
-	if (small_buffer_pool == NULL) {
-		printk(KERN_ERR
-		       "sa1111_dmabuf: could not allocate small pci pool\n");
-		return -ENOMEM;
-	}
-
-	large_buffer_pool = dma_pool_create("sa1111_large_dma_buffer",
-					    NULL, SIZE_LARGE,
-					    0 /* byte alignment */,
-					    0 /* no page-crossing issues */);
-	if (large_buffer_pool == NULL) {
-		printk(KERN_ERR
-		       "sa1111_dmabuf: could not allocate large pci pool\n");
-		dma_pool_destroy(small_buffer_pool);
-		small_buffer_pool = NULL;
-		return -ENOMEM;
-	}
-
-	printk(KERN_INFO "SA1111: DMA buffer sizes: small=%u, large=%u\n",
-	       SIZE_SMALL, SIZE_LARGE);
+	struct list_head *entry;
 
-	return 0;
-}
+	list_for_each(entry, &dmabounce_devs) {
+		struct dmabounce_device_info *d =
+			list_entry(entry, struct dmabounce_device_info, node);
 
-static void __exit destroy_safe_buffer_pools(void)
-{
-	if (small_buffer_pool)
-		dma_pool_destroy(small_buffer_pool);
-	if (large_buffer_pool)
-		dma_pool_destroy(large_buffer_pool);
-
-	small_buffer_pool = large_buffer_pool = NULL;
+		if (d->dev == dev)
+			return d;
+	}
 }
 
 
 /* allocate a 'safe' buffer and keep track of it */
-static struct safe_buffer *alloc_safe_buffer(struct device *dev, void *ptr,
-					     size_t size,
-					     enum dma_data_direction dir)
+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 dma_pool *pool;
+	struct device *dev = device_info->dev;
 	void *safe;
 	dma_addr_t safe_dma_addr;
 
-	dev_dbg(dev, "%s(ptr=%p, size=%d, direction=%d)\n",
+	dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 		__func__, ptr, size, dir);
 
-	DO_STATS ( total_allocs++ );
+	DO_STATS ( device_info->total_allocs++ );
 
 	buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
-	if (buf == NULL) {
-		printk(KERN_WARNING "%s: kmalloc failed\n", __func__);
+	if (buf == 0) {
+		dev_warn(dev, "%s: kmalloc failed\n", __func__);
 		return 0;
 	}
 
-	if (size <= SIZE_SMALL) {
-		pool = small_buffer_pool;
+	if (size <= device_info->small_buffer_size) {
+		pool = device_info->small_buffer_pool;
 		safe = dma_pool_alloc(pool, GFP_ATOMIC, &safe_dma_addr);
 
-		DO_STATS ( sbp_allocs++ );
-	} else if (size <= SIZE_LARGE) {
-		pool = large_buffer_pool;
+		DO_STATS ( device_info->sbp_allocs++ );
+	} else if (size <= device_info->large_buffer_size) {
+		pool = device_info->large_buffer_pool;
 		safe = dma_pool_alloc(pool, GFP_ATOMIC, &safe_dma_addr);
 
-		DO_STATS ( lbp_allocs++ );
+		DO_STATS ( device_info->lbp_allocs++ );
 	} else {
-		pool = NULL;
+		pool = 0;
 		safe = dma_alloc_coherent(dev, size, &safe_dma_addr, GFP_ATOMIC);
 	}
 
-	if (safe == NULL) {
-		printk(KERN_WARNING
-		       "%s: could not alloc dma memory (size=%d)\n",
+	if (safe == 0) {
+		dev_warn(device_info->dev,
+			"%s: could not alloc dma memory (size=%d)\n",
 		       __func__, size);
 		kfree(buf);
 		return 0;
 	}
 
 #ifdef STATS
-	if (total_allocs % 1000 == 0)
-		print_alloc_stats();
+	if (device_info->total_allocs % 1000 == 0)
+		print_alloc_stats(device_info);
 #endif
 
-	BUG_ON(sa1111_check_dma_bug(safe_dma_addr));	// paranoia
-
 	buf->ptr = ptr;
 	buf->size = size;
 	buf->direction = dir;
 	buf->pool = pool;
 	buf->safe = safe;
 	buf->safe_dma_addr = safe_dma_addr;
-	buf->dev = dev;
 
-	list_add(&buf->node, &safe_buffers);
+	list_add(&buf->node, &device_info->safe_buffers);
 
 	return buf;
 }
 
 /* determine if a buffer is from our "safe" pool */
-static struct safe_buffer *find_safe_buffer(struct device *dev,
-					    dma_addr_t safe_dma_addr)
+static inline struct safe_buffer *
+find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 {
 	struct list_head *entry;
 
-	list_for_each(entry, &safe_buffers) {
+	list_for_each(entry, &device_info->safe_buffers) {
 		struct safe_buffer *b =
 			list_entry(entry, struct safe_buffer, node);
 
-		if (b->safe_dma_addr == safe_dma_addr &&
-		    b->dev == dev) {
+		if (b->safe_dma_addr == safe_dma_addr)
 			return b;
-		}
 	}
 
-	return 0;
+	return NULL;
 }
 
-static void free_safe_buffer(struct safe_buffer *buf)
+static inline void
+free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 {
-	pr_debug("%s(buf=%p)\n", __func__, buf);
+	dev_dbg(dev_info->dev, "%s(buf=%p)\n", __func__, buf);
 
 	list_del(&buf->node);
 
 	if (buf->pool)
 		dma_pool_free(buf->pool, buf->safe, buf->safe_dma_addr);
 	else
-		dma_free_coherent(buf->dev, buf->size, buf->safe,
-				  buf->safe_dma_addr);
-	kfree(buf);
-}
-
-static inline int dma_range_is_safe(struct device *dev, dma_addr_t addr,
-				    size_t size)
-{
-	unsigned int physaddr = SA1111_DMA_ADDR((unsigned int) addr);
-
-	/* Any address within one megabyte of the start of the target
-         * bank will be OK.  This is an overly conservative test:
-         * other addresses can be OK depending on the dram
-         * configuration.  (See sa1111.c:sa1111_check_dma_bug() * for
-         * details.)
-	 *
-	 * We take care to ensure the entire dma region is within
-	 * the safe range.
-	 */
+		dma_free_coherent(device_info->dev, buf->size, buf->safe,
+				    buf->safe_dma_addr);
 
-	return ((physaddr + size - 1) < (1<<20));
+	kfree(buf);
 }
 
 /* ************************************************** */
 
 #ifdef STATS
-static unsigned long map_op_count __initdata = 0;
-static unsigned long bounce_count __initdata = 0;
 
-static void print_map_stats(void)
+static void print_map_stats(struct dmabounce_device_info *device_info)
 {
 	printk(KERN_INFO
-	       "sa1111_dmabuf: map_op_count=%lu, bounce_count=%lu\n",
-	       map_op_count, bounce_count);
+		"%s: dmabounce: map_op_count=%lu, bounce_count=%lu\n",
+		device_info->dev->bus_id,
+		device_info->map_op_count, device_info->bounce_count);
 }
 #endif
 
-static dma_addr_t map_single(struct device *dev, void *ptr,
-			     size_t size, enum dma_data_direction dir)
+static inline dma_addr_t
+map_single(struct device *dev, void *ptr, size_t size,
+		enum dma_data_direction dir)
 {
 	dma_addr_t dma_addr;
+	struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 
-	DO_STATS ( map_op_count++ );
+	if (device_info)
+		DO_STATS ( device_info->map_op_count++ );
+
+	if (dev->dma_mask) {
+		unsigned long limit;
+
+		limit = (*dev->dma_mask + 1) & ~(*dev->dma_mask);
+		if (limit && (size > limit)) {
+			dev_err(dev, "DMA mapping too big "
+				"(requested %#x mask %#Lx)\n",
+				size, *dev->dma_mask);
+			return ~0;
+		}
+	}
 
 	dma_addr = virt_to_bus(ptr);
 
-	if (!dma_range_is_safe(dev, dma_addr, size)) {
+	if (device_info && dma_needs_bounce(dev, dma_addr, size)) {
 		struct safe_buffer *buf;
 
-		DO_STATS ( bounce_count++ ) ;
-
-		buf = alloc_safe_buffer(dev, ptr, size, dir);
-		if (buf == NULL) {
-			printk(KERN_ERR
-			       "%s: unable to map unsafe buffer %p!\n",
+		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=%08lx) mapped to %p (phy=%08x)\n",
-			__func__,
-			buf->ptr, virt_to_bus(buf->ptr),
-			buf->safe, buf->safe_dma_addr);
+		dev_dbg(dev,
+			"%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
+			__func__, buf->ptr, (void *) virt_to_bus(buf->ptr),
+			buf->safe, (void *) buf->safe_dma_addr);
 
-		if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
-			dev_dbg(dev, "%s: copy out from unsafe %p, to safe %p, size %d\n",
+		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);
 		}
+		consistent_sync(buf->safe, size, dir);
 
 		dma_addr = buf->safe_dma_addr;
-		ptr = buf->safe;
+	} else {
+		consistent_sync(ptr, size, dir);
 	}
 
-	consistent_sync(ptr, size, dir);
-
-#ifdef STATS
-	if (map_op_count % 1000 == 0)
-		print_map_stats();
-#endif
-
 	return dma_addr;
 }
 
-static void unmap_single(struct device *dev, dma_addr_t dma_addr,
-			 size_t size, enum dma_data_direction dir)
+static inline void
+unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
+		enum dma_data_direction dir)
 {
-	struct safe_buffer *buf;
+	struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
+	struct safe_buffer *buf = NULL;
+
+	/*
+	 * Trying to unmap an invalid mapping
+	 */
+	if (dma_addr == ~0) {
+		dev_err(dev, "Trying to unmap invalid mapping\n");
+		return;
+	}
 
-	buf = find_safe_buffer(dev, dma_addr);
+	if (device_info)
+		buf = find_safe_buffer(device_info, dma_addr);
 
 	if (buf) {
 		BUG_ON(buf->size != size);
-		BUG_ON(buf->direction != dir);
 
-		dev_dbg(dev, "%s: unsafe buffer %p (phy=%08lx) mapped to %p (phy=%08lx)\n",
-			__func__,
-			buf->ptr, virt_to_bus(buf->ptr),
-			buf->safe, buf->safe_dma_addr);
+		dev_dbg(dev,
+			"%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
+			__func__, buf->ptr, (void *) virt_to_bus(buf->ptr),
+			buf->safe, (void *) buf->safe_dma_addr);
 
-		DO_STATS ( bounce_count++ );
 
-		if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
-			dev_dbg(dev, "%s: copy back from safe %p, to unsafe %p size %d\n",
+		DO_STATS ( device_info->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, buf->ptr, size);
 			memcpy(buf->ptr, buf->safe, size);
 		}
-		free_safe_buffer(buf);
+		free_safe_buffer(device_info, buf);
 	}
 }
 
-static void sync_single(struct device *dev, dma_addr_t dma_addr,
-			size_t size, enum dma_data_direction dir)
+static inline void
+sync_single(struct device *dev, dma_addr_t dma_addr, size_t size,
+		enum dma_data_direction dir)
 {
-	struct safe_buffer *buf;
-	void *ptr;
+	struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
+	struct safe_buffer *buf = NULL;
 
-	buf = find_safe_buffer(dev, dma_addr);
+	if (device_info)
+		buf = find_safe_buffer(device_info, dma_addr);
 
 	if (buf) {
-		BUG_ON(buf->size != size);
-		BUG_ON(buf->direction != dir);
-
-		dev_dbg(dev, "%s: unsafe buffer %p (phy=%08lx) mapped to %p (phy=%08lx)\n",
-			__func__,
-			buf->ptr, virt_to_bus(buf->ptr),
-			buf->safe, buf->safe_dma_addr);
-
-		DO_STATS ( bounce_count++ );
+		/*
+		 * 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_bus(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 from safe %p, to unsafe %p size %d\n",
+			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 from unsafe %p, to safe %p, size %d\n",
+			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;
@@ -353,11 +364,10 @@ static void sync_single(struct device *dev, dma_addr_t dma_addr,
 		default:
 			BUG();
 		}
-		ptr = buf->safe;
+		consistent_sync(buf->safe, size, dir);
 	} else {
-		ptr = bus_to_virt(dma_addr);
+		consistent_sync(bus_to_virt(dma_addr), size, dir);
 	}
-	consistent_sync(ptr, size, dir);
 }
 
 /* ************************************************** */
@@ -368,14 +378,15 @@ static void sync_single(struct device *dev, dma_addr_t dma_addr,
  * substitute the safe buffer for the unsafe one.
  * (basically move the buffer from an unsafe area to a safe one)
  */
-dma_addr_t sa1111_map_single(struct device *dev, void *ptr,
-			     size_t size, enum dma_data_direction dir)
+dma_addr_t
+dma_map_single(struct device *dev, void *ptr, size_t size,
+		enum dma_data_direction dir)
 {
 	unsigned long flags;
 	dma_addr_t dma_addr;
 
 	dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
-	       __func__, ptr, size, dir);
+		__func__, ptr, size, dir);
 
 	BUG_ON(dir == DMA_NONE);
 
@@ -394,13 +405,17 @@ dma_addr_t sa1111_map_single(struct device *dev, void *ptr,
  * the safe buffer.  (basically return things back to the way they
  * should be)
  */
-void sa1111_unmap_single(struct device *dev, dma_addr_t dma_addr,
-		         size_t size, enum dma_data_direction dir)
+
+void
+dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
+			enum dma_data_direction dir)
 {
 	unsigned long flags;
 
-	dev_dbg(dev, "%s(ptr=%08lx,size=%d,dir=%x)\n",
-		__func__, dma_addr, size, dir);
+	dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
+		__func__, (void *) dma_addr, size, dir);
+
+	BUG_ON(dir == DMA_NONE);
 
 	local_irq_save(flags);
 
@@ -409,8 +424,9 @@ void sa1111_unmap_single(struct device *dev, dma_addr_t dma_addr,
 	local_irq_restore(flags);
 }
 
-int sa1111_map_sg(struct device *dev, struct scatterlist *sg,
-		  int nents, enum dma_data_direction dir)
+int
+dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
+		enum dma_data_direction dir)
 {
 	unsigned long flags;
 	int i;
@@ -428,7 +444,8 @@ int sa1111_map_sg(struct device *dev, struct scatterlist *sg,
 		unsigned int length = sg->length;
 		void *ptr = page_address(page) + offset;
 
-		sg->dma_address = map_single(dev, ptr, length, dir);
+		sg->dma_address =
+			map_single(dev, ptr, length, dir);
 	}
 
 	local_irq_restore(flags);
@@ -436,8 +453,9 @@ int sa1111_map_sg(struct device *dev, struct scatterlist *sg,
 	return nents;
 }
 
-void sa1111_unmap_sg(struct device *dev, struct scatterlist *sg,
-		     int nents, enum dma_data_direction dir)
+void
+dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
+		enum dma_data_direction dir)
 {
 	unsigned long flags;
 	int i;
@@ -445,6 +463,8 @@ void sa1111_unmap_sg(struct device *dev, struct scatterlist *sg,
 	dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 		__func__, sg, nents, dir);
 
+	BUG_ON(dir == DMA_NONE);
+
 	local_irq_save(flags);
 
 	for (i = 0; i < nents; i++, sg++) {
@@ -457,13 +477,14 @@ void sa1111_unmap_sg(struct device *dev, struct scatterlist *sg,
 	local_irq_restore(flags);
 }
 
-void sa1111_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr,
-				    size_t size, enum dma_data_direction dir)
+void
+dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size,
+				enum dma_data_direction dir)
 {
 	unsigned long flags;
 
-	dev_dbg(dev, "%s(ptr=%08lx,size=%d,dir=%x)\n",
-		__func__, dma_addr, size, dir);
+	dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
+		__func__, (void *) dma_addr, size, dir);
 
 	local_irq_save(flags);
 
@@ -472,13 +493,14 @@ void sa1111_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr,
 	local_irq_restore(flags);
 }
 
-void sa1111_dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr,
-				       size_t size, enum dma_data_direction dir)
+void
+dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size,
+				enum dma_data_direction dir)
 {
 	unsigned long flags;
 
-	dev_dbg(dev, "%s(ptr=%08lx,size=%d,dir=%x)\n",
-		__func__, dma_addr, size, dir);
+	dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
+		__func__, (void *) dma_addr, size, dir);
 
 	local_irq_save(flags);
 
@@ -487,8 +509,9 @@ void sa1111_dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr,
 	local_irq_restore(flags);
 }
 
-void sa1111_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
-				int nents, enum dma_data_direction dir)
+void
+dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
+			enum dma_data_direction dir)
 {
 	unsigned long flags;
 	int i;
@@ -496,6 +519,8 @@ void sa1111_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
 	dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 		__func__, sg, nents, dir);
 
+	BUG_ON(dir == DMA_NONE);
+
 	local_irq_save(flags);
 
 	for (i = 0; i < nents; i++, sg++) {
@@ -508,8 +533,9 @@ void sa1111_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
 	local_irq_restore(flags);
 }
 
-void sa1111_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
-				   int nents, enum dma_data_direction dir)
+void
+dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
+			enum dma_data_direction dir)
 {
 	unsigned long flags;
 	int i;
@@ -517,6 +543,8 @@ void sa1111_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 	dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 		__func__, sg, nents, dir);
 
+	BUG_ON(dir == DMA_NONE);
+
 	local_irq_save(flags);
 
 	for (i = 0; i < nents; i++, sg++) {
@@ -529,38 +557,119 @@ void sa1111_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 	local_irq_restore(flags);
 }
 
-EXPORT_SYMBOL(sa1111_map_single);
-EXPORT_SYMBOL(sa1111_unmap_single);
-EXPORT_SYMBOL(sa1111_map_sg);
-EXPORT_SYMBOL(sa1111_unmap_sg);
-EXPORT_SYMBOL(sa1111_dma_sync_single_for_cpu);
-EXPORT_SYMBOL(sa1111_dma_sync_single_for_device);
-EXPORT_SYMBOL(sa1111_dma_sync_sg_for_cpu);
-EXPORT_SYMBOL(sa1111_dma_sync_sg_for_device);
+int
+dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
+			unsigned long large_buffer_size)
+{
+	struct dmabounce_device_info *device_info;
 
-/* **************************************** */
+	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;
+	}
 
-static int __init sa1111_dmabuf_init(void)
-{
-	printk(KERN_DEBUG "sa1111_dmabuf: initializing SA-1111 DMA buffers\n");
+	device_info->small_buffer_pool =
+		dma_pool_create("small_dmabounce_pool",
+				dev,
+				small_buffer_size,
+				0 /* byte alignment */,
+				0 /* no page-crossing issues */);
+	if (!device_info->small_buffer_pool) {
+		printk(KERN_ERR
+			"dmabounce: could not allocate small DMA pool for %s\n",
+			dev->bus_id);
+		kfree(device_info);
+		return -ENOMEM;
+	}
+
+	if (large_buffer_size) {
+		device_info->large_buffer_pool =
+			dma_pool_create("large_dmabounce_pool",
+					dev,
+					large_buffer_size,
+					0 /* byte alignment */,
+					0 /* no page-crossing issues */);
+		if (!device_info->large_buffer_pool) {
+		printk(KERN_ERR
+			"dmabounce: could not allocate large DMA pool for %s\n",
+			dev->bus_id);
+			dma_pool_destroy(device_info->small_buffer_pool);
+
+			return -ENOMEM;
+		}
+	}
+
+	device_info->dev = dev;
+	device_info->small_buffer_size = small_buffer_size;
+	device_info->large_buffer_size = large_buffer_size;
+	INIT_LIST_HEAD(&device_info->safe_buffers);
+
+#ifdef STATS
+	device_info->sbp_allocs = 0;
+	device_info->lbp_allocs = 0;
+	device_info->total_allocs = 0;
+	device_info->map_op_count = 0;
+	device_info->bounce_count = 0;
+#endif
+
+	list_add(&device_info->node, &dmabounce_devs);
 
-	return create_safe_buffer_pools();
+	printk(KERN_INFO "dmabounce: registered device %s on %s bus\n",
+		dev->bus_id, dev->bus->name);
+
+	return 0;
 }
-module_init(sa1111_dmabuf_init);
 
-static void __exit sa1111_dmabuf_exit(void)
+void
+dmabounce_unregister_dev(struct device *dev)
 {
-	BUG_ON(!list_empty(&safe_buffers));
+	struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
+
+	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_buffer_pool)
+		dma_pool_destroy(device_info->small_buffer_pool);
+	if (device_info->large_buffer_pool)
+		dma_pool_destroy(device_info->large_buffer_pool);
 
 #ifdef STATS
-	print_alloc_stats();
-	print_map_stats();
+	print_alloc_stats(device_info);
+	print_map_stats(device_info);
 #endif
 
-	destroy_safe_buffer_pools();
+	list_del(&device_info->node);
+
+	kfree(device_info);
+
+	printk(KERN_INFO "dmabounce: device %s on %s bus unregistered\n",
+		dev->bus_id, dev->bus->name);
 }
-module_exit(sa1111_dmabuf_exit);
 
-MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>");
-MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for SA-1111.");
+
+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);
+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");

arch/arm/common/sa1111.c

@@ -25,6 +25,7 @@
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/dma-mapping.h>
 
 #include <asm/hardware.h>
 #include <asm/mach-types.h>
@@ -547,15 +548,6 @@ sa1111_init_one_child(struct sa1111 *sachip, struct resource *parent,
 	snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id),
 		 "%4.4lx", info->offset);
 
-	/*
-	 * If the parent device has a DMA mask associated with it,
-	 * propagate it down to the children.
-	 */
-	if (sachip->dev->dma_mask) {
-		dev->dma_mask = *sachip->dev->dma_mask;
-		dev->dev.dma_mask = &dev->dma_mask;
-	}
-
 	dev->devid	 = info->devid;
 	dev->dev.parent  = sachip->dev;
 	dev->dev.bus     = &sa1111_bus_type;
@@ -573,15 +565,37 @@ sa1111_init_one_child(struct sa1111 *sachip, struct resource *parent,
 	if (ret) {
 		printk("SA1111: failed to allocate resource for %s\n",
 			dev->res.name);
+		kfree(dev);
 		goto out;
 	}
 
+
 	ret = device_register(&dev->dev);
 	if (ret) {
 		release_resource(&dev->res);
- out:
 		kfree(dev);
+		goto out;
+	}
+
+	/*
+	 * If the parent device has a DMA mask associated with it,
+	 * propagate it down to the children.
+	 */
+	if (sachip->dev->dma_mask) {
+		dev->dma_mask = *sachip->dev->dma_mask;
+		dev->dev.dma_mask = &dev->dma_mask;
+
+		if (dev->dma_mask != 0xffffffffUL) {
+			ret = dmabounce_register_dev(&dev->dev, 1024, 4096);
+			if (ret) {
+				printk("SA1111: Failed to register %s with dmabounce", dev->dev.bus_id);
+				kfree(dev);
+				device_unregister(dev);
+			}
+		}
 	}
+
+out:
 	return ret;
 }
 
@@ -742,61 +756,31 @@ static void __sa1111_remove(struct sa1111 *sachip)
  *
  * This routine only identifies whether or not a given DMA address
  * is susceptible to the bug.
+ *
+ * This should only get called for sa1111_device types due to the
+ * way we configure our device dma_masks.
  */
-int sa1111_check_dma_bug(dma_addr_t addr)
+int dma_needs_bounce(struct device *dev, dma_addr_t addr, size_t size)
 {
-	struct sa1111 *sachip = g_sa1111;
 	unsigned int physaddr = SA1111_DMA_ADDR((unsigned int)addr);
-	unsigned int smcr;
+	u32 dma_mask = *dev->dma_mask;
 
-	/* Section 4.6 of the "Intel StrongARM SA-1111 Development Module
+	/*
+	 * Section 4.6 of the "Intel StrongARM SA-1111 Development Module
 	 * User's Guide" mentions that jumpers R51 and R52 control the
 	 * target of SA-1111 DMA (either SDRAM bank 0 on Assabet, or
 	 * SDRAM bank 1 on Neponset). The default configuration selects
 	 * Assabet, so any address in bank 1 is necessarily invalid.
 	 */
-	if ((machine_is_assabet() || machine_is_pfs168()) && addr >= 0xc8000000)
-	  	return -1;
+	if ((machine_is_assabet() || machine_is_pfs168()) &&
+		(addr >= 0xc8000000 || (addr + size) >= 0xc8000000))
+	  	return 1;
 
-	/* The bug only applies to buffers located more than one megabyte
-	 * above the start of the target bank:
+	/*
+	 * Check to see if either the start or end are illegal.
 	 */
-	if (physaddr<(1<<20))
-		return 0;
-
-	smcr = sa1111_readl(sachip->base + SA1111_SMCR);
-	switch (FExtr(smcr, SMCR_DRAC)) {
-	case 01: /* 10 row + bank address bits, A<20> must not be set */
-	  	if (physaddr & (1<<20))
-		  	return -1;
-		break;
-	case 02: /* 11 row + bank address bits, A<23> must not be set */
-	  	if (physaddr & (1<<23))
-		  	return -1;
-		break;
-	case 03: /* 12 row + bank address bits, A<24> must not be set */
-	  	if (physaddr & (1<<24))
-		  	return -1;
-		break;
-	case 04: /* 13 row + bank address bits, A<25> must not be set */
-	  	if (physaddr & (1<<25))
-		  	return -1;
-		break;
-	case 05: /* 14 row + bank address bits, A<20> must not be set */
-	  	if (physaddr & (1<<20))
-		  	return -1;
-		break;
-	case 06: /* 15 row + bank address bits, A<20> must not be set */
-	  	if (physaddr & (1<<20))
-		  	return -1;
-		break;
-	default:
-	  	printk(KERN_ERR "%s(): invalid SMCR DRAC value 0%lo\n",
-		       __FUNCTION__, FExtr(smcr, SMCR_DRAC));
-		return -1;
-	}
-
-	return 0;
+	return ((addr & ~(*dev->dma_mask))) ||
+		((addr + size - 1) & ~(*dev->dma_mask));
 }
 
 struct sa1111_save_data {
@@ -1293,7 +1277,6 @@ module_exit(sa1111_exit);
 MODULE_DESCRIPTION("Intel Corporation SA1111 core driver");
 MODULE_LICENSE("GPL");
 
-EXPORT_SYMBOL(sa1111_check_dma_bug);
 EXPORT_SYMBOL(sa1111_select_audio_mode);
 EXPORT_SYMBOL(sa1111_set_audio_rate);
 EXPORT_SYMBOL(sa1111_get_audio_rate);

include/asm-arm/dma-mapping.h

@@ -16,29 +16,6 @@
  */
 extern void consistent_sync(void *kaddr, size_t size, int rw);
 
-/*
- * For SA-1111 these functions are "magic" and utilize bounce
- * bufferes as needed to work around SA-1111 DMA bugs.
- */
-dma_addr_t sa1111_map_single(struct device *dev, void *, size_t, enum dma_data_direction);
-void sa1111_unmap_single(struct device *dev, dma_addr_t, size_t, enum dma_data_direction);
-int sa1111_map_sg(struct device *dev, struct scatterlist *, int, enum dma_data_direction);
-void sa1111_unmap_sg(struct device *dev, struct scatterlist *, int, enum dma_data_direction);
-void sa1111_dma_sync_single_for_cpu(struct device *dev, dma_addr_t, size_t, enum dma_data_direction);
-void sa1111_dma_sync_single_for_device(struct device *dev, dma_addr_t, size_t, enum dma_data_direction);
-void sa1111_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *, int, enum dma_data_direction);
-void sa1111_dma_sync_sg_for_device(struct device *dev, struct scatterlist *, int, enum dma_data_direction);
-
-#ifdef CONFIG_SA1111
-
-extern struct bus_type sa1111_bus_type;
-
-#define dmadev_is_sa1111(dev)	((dev)->bus == &sa1111_bus_type)
-
-#else
-#define dmadev_is_sa1111(dev)	(0)
-#endif
-
 /*
  * Return whether the given device DMA address mask can be supported
  * properly.  For example, if your device can only drive the low 24-bits
@@ -70,6 +47,14 @@ static inline int dma_is_consistent(dma_addr_t handle)
 	return 0;
 }
 
+/*
+ * DMA errors are defined by all-bits-set in the DMA address.
+ */
+static inline int dma_mapping_error(dma_addr_t dma_addr)
+{
+	return dma_addr == ~0;
+}
+
 /**
  * dma_alloc_coherent - allocate consistent memory for DMA
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
@@ -118,6 +103,7 @@ dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, int
 #define dma_free_writecombine(dev,size,cpu_addr,handle) \
 	dma_free_coherent(dev,size,cpu_addr,handle)
 
+
 /**
  * dma_map_single - map a single buffer for streaming DMA
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
@@ -132,16 +118,17 @@ dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, int
  * can regain ownership by calling dma_unmap_single() or
  * dma_sync_single_for_cpu().
  */
+#ifndef CONFIG_DMABOUNCE
 static inline dma_addr_t
 dma_map_single(struct device *dev, void *cpu_addr, size_t size,
 	       enum dma_data_direction dir)
 {
-	if (dmadev_is_sa1111(dev))
-		return sa1111_map_single(dev, cpu_addr, size, dir);
-
 	consistent_sync(cpu_addr, size, dir);
 	return __virt_to_bus((unsigned long)cpu_addr);
 }
+#else
+extern dma_addr_t dma_map_single(struct device *,void *, size_t, enum dma_data_direction);
+#endif
 
 /**
  * dma_map_page - map a portion of a page for streaming DMA
@@ -180,15 +167,16 @@ dma_map_page(struct device *dev, struct page *page,
  * After this call, reads by the CPU to the buffer are guaranteed to see
  * whatever the device wrote there.
  */
+#ifndef CONFIG_DMABOUNCE
 static inline void
 dma_unmap_single(struct device *dev, dma_addr_t handle, size_t size,
 		 enum dma_data_direction dir)
 {
-	if (dmadev_is_sa1111(dev))
-		sa1111_unmap_single(dev, handle, size, dir);
-
 	/* nothing to do */
 }
+#else
+extern void dma_unmap_single(struct device *, dma_addr_t, size_t, enum dma_data_direction);
+#endif
 
 /**
  * dma_unmap_page - unmap a buffer previously mapped through dma_map_page()
@@ -233,15 +221,13 @@ dma_unmap_page(struct device *dev, dma_addr_t handle, size_t size,
  * Device ownership issues as mentioned above for dma_map_single are
  * the same here.
  */
+#ifndef CONFIG_DMABOUNCE
 static inline int
 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 	   enum dma_data_direction dir)
 {
 	int i;
 
-	if (dmadev_is_sa1111(dev))
-		return sa1111_map_sg(dev, sg, nents, dir);
-
 	for (i = 0; i < nents; i++, sg++) {
 		char *virt;
 
@@ -252,6 +238,9 @@ dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 
 	return nents;
 }
+#else
+extern int dma_map_sg(struct device *, struct scatterlist *, int, enum dma_data_direction);
+#endif
 
 /**
  * dma_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
@@ -264,17 +253,18 @@ dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
  * Again, CPU read rules concerning calls here are the same as for
  * dma_unmap_single() above.
  */
+#ifndef CONFIG_DMABOUNCE
 static inline void
 dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 	     enum dma_data_direction dir)
 {
-	if (dmadev_is_sa1111(dev)) {
-		sa1111_unmap_sg(dev, sg, nents, dir);
-		return;
-	}
 
 	/* nothing to do */
 }
+#else
+extern void dma_unmap_sg(struct device *, struct scatterlist *, int, enum dma_data_direction);
+#endif
+
 
 /**
  * dma_sync_single_for_cpu
@@ -293,15 +283,11 @@ dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
  * must first the perform a dma_sync_for_device, and then the
  * device again owns the buffer.
  */
+#ifndef CONFIG_DMABOUNCE
 static inline void
 dma_sync_single_for_cpu(struct device *dev, dma_addr_t handle, size_t size,
 			enum dma_data_direction dir)
 {
-	if (dmadev_is_sa1111(dev)) {
-		sa1111_dma_sync_single_for_cpu(dev, handle, size, dir);
-		return;
-	}
-
 	consistent_sync((void *)__bus_to_virt(handle), size, dir);
 }
 
@@ -309,13 +295,13 @@ static inline void
 dma_sync_single_for_device(struct device *dev, dma_addr_t handle, size_t size,
 			   enum dma_data_direction dir)
 {
-	if (dmadev_is_sa1111(dev)) {
-		sa1111_dma_sync_single_for_device(dev, handle, size, dir);
-		return;
-	}
-
 	consistent_sync((void *)__bus_to_virt(handle), size, dir);
 }
+#else
+extern void dma_sync_single_for_cpu(struct device*, dma_addr_t, size_t, enum dma_data_direction);
+extern void dma_sync_single_for_device(struct device*, dma_addr_t, size_t, enum dma_data_direction);
+#endif
+
 
 /**
  * dma_sync_sg_for_cpu
@@ -330,17 +316,13 @@ dma_sync_single_for_device(struct device *dev, dma_addr_t handle, size_t size,
  * The same as dma_sync_single_for_* but for a scatter-gather list,
  * same rules and usage.
  */
+#ifndef CONFIG_DMABOUNCE
 static inline void
 dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
 		    enum dma_data_direction dir)
 {
 	int i;
 
-	if (dmadev_is_sa1111(dev)) {
-		sa1111_dma_sync_sg_for_cpu(dev, sg, nents, dir);
-		return;
-	}
-
 	for (i = 0; i < nents; i++, sg++) {
 		char *virt = page_address(sg->page) + sg->offset;
 		consistent_sync(virt, sg->length, dir);
@@ -353,24 +335,73 @@ dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
 {
 	int i;
 
-	if (dmadev_is_sa1111(dev)) {
-		sa1111_dma_sync_sg_for_device(dev, sg, nents, dir);
-		return;
-	}
-
 	for (i = 0; i < nents; i++, sg++) {
 		char *virt = page_address(sg->page) + sg->offset;
 		consistent_sync(virt, sg->length, dir);
 	}
 }
+#else
+extern void dma_sync_sg_for_cpu(struct device*, struct scatterlist*, int, enum dma_data_direction);
+extern void dma_sync_sg_for_device(struct device*, struct scatterlist*, int, enum dma_data_direction);
+#endif
 
+#ifdef CONFIG_DMABOUNCE
 /*
- * DMA errors are defined by all-bits-set in the DMA address.
+ * For SA-1111, IXP425, and ADI systems  the dma-mapping functions are "magic"
+ * and utilize bounce buffers as needed to work around limited DMA windows.
+ *
+ * On the SA-1111, a bug limits DMA to only certain regions of RAM.
+ * On the IXP425, the PCI inbound window is 64MB (256MB total RAM)
+ * On some ADI engineering sytems, PCI inbound window is 32MB (12MB total RAM)
+ *
+ * The following are helper functions used by the dmabounce subystem
+ *
  */
-static inline int dma_mapping_error(dma_addr_t dma_addr)
-{
-	return dma_addr == ~0;
-}
+
+/**
+ * dmabounce_register_dev
+ *
+ * @dev: valid struct device pointer
+ * @small_buf_size: size of buffers to use with small buffer pool
+ * @large_buf_size: size of buffers to use with large buffer pool (can be 0)
+ *
+ * This function should be called by low-level platform code to register
+ * a device as requireing DMA buffer bouncing. The function will allocate
+ * appropriate DMA pools for the device.
+ *
+ */
+extern int dmabounce_register_dev(struct device *, unsigned long, unsigned long);
+
+/**
+ * dmabounce_unregister_dev
+ *
+ * @dev: valid struct device pointer
+ *
+ * This function should be called by low-level platform code when device
+ * that was previously registered with dmabounce_register_dev is removed
+ * from the system.
+ *
+ */
+extern void dmabounce_unregister_dev(struct device *);
+
+/**
+ * dma_needs_bounce
+ *
+ * @dev: valid struct device pointer
+ * @dma_handle: dma_handle of unbounced buffer
+ * @size: size of region being mapped
+ *
+ * Platforms that utilize the dmabounce mechanism must implement
+ * this function.
+ *
+ * The dmabounce routines call this function whenever a dma-mapping
+ * is requested to determine whether a given buffer needs to be bounced
+ * or not. The function must return 0 if the the buffer is OK for
+ * DMA access and 1 if the buffer needs to be bounced.
+ *
+ */
+extern int dma_needs_bounce(struct device*, dma_addr_t, size_t);
+#endif /* CONFIG_DMABOUNCE */
 
 #endif /* __KERNEL__ */
 #endif