1 files changed, 532 insertions, 0 deletions
diff --git a/arch/arm/common/dmabounce.c b/arch/arm/common/dmabounce.c
new file mode 100644
index 00000000..595ecd29
--- /dev/null
+++ b/arch/arm/common/dmabounce.c
@@ -0,0 +1,532 @@
+/*
+ *  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/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>
+
+#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) {
+			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)
+{
+	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 ~0;
+	}
+
+	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) {
+		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)
+{
+	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) {
+		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)
+ */
+dma_addr_t __dma_map_page(struct device *dev, struct page *page,
+		unsigned long offset, size_t size, enum dma_data_direction dir)
+{
+	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 ~0;
+
+	if (ret == 0) {
+		__dma_page_cpu_to_dev(page, offset, size, dir);
+		return dma_addr;
+	}
+
+	if (PageHighMem(page)) {
+		dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
+		return ~0;
+	}
+
+	return map_single(dev, page_address(page) + offset, size, dir);
+}
+EXPORT_SYMBOL(__dma_map_page);
+
+/*
+ * 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_page(struct device *dev, dma_addr_t dma_addr, size_t size,
+		enum dma_data_direction dir)
+{
+	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) {
+		__dma_page_dev_to_cpu(pfn_to_page(dma_to_pfn(dev, dma_addr)),
+			dma_addr & ~PAGE_MASK, size, dir);
+		return;
+	}
+
+	unmap_single(dev, buf, size, dir);
+}
+EXPORT_SYMBOL(__dma_unmap_page);
+
+int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
+		unsigned long off, size_t sz, enum dma_data_direction dir)
+{
+	struct safe_buffer *buf;
+
+	dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
+		__func__, addr, off, sz, dir);
+
+	buf = find_safe_buffer_dev(dev, addr, __func__);
+	if (!buf)
+		return 1;
+
+	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) {
+		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;
+}
+EXPORT_SYMBOL(dmabounce_sync_for_cpu);
+
+int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
+		unsigned long off, size_t sz, enum dma_data_direction dir)
+{
+	struct safe_buffer *buf;
+
+	dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
+		__func__, addr, off, sz, dir);
+
+	buf = find_safe_buffer_dev(dev, addr, __func__);
+	if (!buf)
+		return 1;
+
+	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_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;
+}
+EXPORT_SYMBOL(dmabounce_sync_for_device);
+
+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;
+
+	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;
+
+	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");