diff --git a/sound/core/pcm_memory.c b/sound/core/pcm_memory.c
new file mode 100644
index 0000000..f1d5f7a
--- /dev/null
+++ b/sound/core/pcm_memory.c
@@ -0,0 +1,363 @@
+/*
+ *  Digital Audio (PCM) abstract layer
+ *  Copyright (c) by Jaroslav Kysela <perex@suse.cz>
+ *
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ */
+
+#include <sound/driver.h>
+#include <asm/io.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/info.h>
+#include <sound/initval.h>
+
+static int preallocate_dma = 1;
+module_param(preallocate_dma, int, 0444);
+MODULE_PARM_DESC(preallocate_dma, "Preallocate DMA memory when the PCM devices are initialized.");
+
+static int maximum_substreams = 4;
+module_param(maximum_substreams, int, 0444);
+MODULE_PARM_DESC(maximum_substreams, "Maximum substreams with preallocated DMA memory.");
+
+static const size_t snd_minimum_buffer = 16384;
+
+
+/*
+ * try to allocate as the large pages as possible.
+ * stores the resultant memory size in *res_size.
+ *
+ * the minimum size is snd_minimum_buffer.  it should be power of 2.
+ */
+static int preallocate_pcm_pages(snd_pcm_substream_t *substream, size_t size)
+{
+	struct snd_dma_buffer *dmab = &substream->dma_buffer;
+	int err;
+
+	snd_assert(size > 0, return -EINVAL);
+
+	/* already reserved? */
+	if (snd_dma_get_reserved_buf(dmab, substream->dma_buf_id) > 0) {
+		if (dmab->bytes >= size)
+			return 0; /* yes */
+		/* no, free the reserved block */
+		snd_dma_free_pages(dmab);
+		dmab->bytes = 0;
+	}
+
+	do {
+		if ((err = snd_dma_alloc_pages(dmab->dev.type, dmab->dev.dev,
+					       size, dmab)) < 0) {
+			if (err != -ENOMEM)
+				return err; /* fatal error */
+		} else
+			return 0;
+		size >>= 1;
+	} while (size >= snd_minimum_buffer);
+	dmab->bytes = 0; /* tell error */
+	return 0;
+}
+
+/*
+ * release the preallocated buffer if not yet done.
+ */
+static void snd_pcm_lib_preallocate_dma_free(snd_pcm_substream_t *substream)
+{
+	if (substream->dma_buffer.area == NULL)
+		return;
+	if (substream->dma_buf_id)
+		snd_dma_reserve_buf(&substream->dma_buffer, substream->dma_buf_id);
+	else
+		snd_dma_free_pages(&substream->dma_buffer);
+	substream->dma_buffer.area = NULL;
+}
+
+/**
+ * snd_pcm_lib_preallocate_free - release the preallocated buffer of the specified substream.
+ * @substream: the pcm substream instance
+ *
+ * Releases the pre-allocated buffer of the given substream.
+ *
+ * Returns zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_lib_preallocate_free(snd_pcm_substream_t *substream)
+{
+	snd_pcm_lib_preallocate_dma_free(substream);
+	if (substream->proc_prealloc_entry) {
+		snd_info_unregister(substream->proc_prealloc_entry);
+		substream->proc_prealloc_entry = NULL;
+	}
+	return 0;
+}
+
+/**
+ * snd_pcm_lib_preallocate_free_for_all - release all pre-allocated buffers on the pcm
+ * @pcm: the pcm instance
+ *
+ * Releases all the pre-allocated buffers on the given pcm.
+ *
+ * Returns zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_lib_preallocate_free_for_all(snd_pcm_t *pcm)
+{
+	snd_pcm_substream_t *substream;
+	int stream;
+
+	for (stream = 0; stream < 2; stream++)
+		for (substream = pcm->streams[stream].substream; substream; substream = substream->next)
+			snd_pcm_lib_preallocate_free(substream);
+	return 0;
+}
+
+/*
+ * read callback for prealloc proc file
+ *
+ * prints the current allocated size in kB.
+ */
+static void snd_pcm_lib_preallocate_proc_read(snd_info_entry_t *entry,
+					      snd_info_buffer_t *buffer)
+{
+	snd_pcm_substream_t *substream = (snd_pcm_substream_t *)entry->private_data;
+	snd_iprintf(buffer, "%lu\n", (unsigned long) substream->dma_buffer.bytes / 1024);
+}
+
+/*
+ * write callback for prealloc proc file
+ *
+ * accepts the preallocation size in kB.
+ */
+static void snd_pcm_lib_preallocate_proc_write(snd_info_entry_t *entry,
+					       snd_info_buffer_t *buffer)
+{
+	snd_pcm_substream_t *substream = (snd_pcm_substream_t *)entry->private_data;
+	char line[64], str[64];
+	size_t size;
+	struct snd_dma_buffer new_dmab;
+
+	if (substream->runtime) {
+		buffer->error = -EBUSY;
+		return;
+	}
+	if (!snd_info_get_line(buffer, line, sizeof(line))) {
+		snd_info_get_str(str, line, sizeof(str));
+		size = simple_strtoul(str, NULL, 10) * 1024;
+		if ((size != 0 && size < 8192) || size > substream->dma_max) {
+			buffer->error = -EINVAL;
+			return;
+		}
+		if (substream->dma_buffer.bytes == size)
+			return;
+		memset(&new_dmab, 0, sizeof(new_dmab));
+		new_dmab.dev = substream->dma_buffer.dev;
+		if (size > 0) {
+			if (snd_dma_alloc_pages(substream->dma_buffer.dev.type,
+						substream->dma_buffer.dev.dev,
+						size, &new_dmab) < 0) {
+				buffer->error = -ENOMEM;
+				return;
+			}
+			substream->buffer_bytes_max = size;
+		} else {
+			substream->buffer_bytes_max = UINT_MAX;
+		}
+		if (substream->dma_buffer.area)
+			snd_dma_free_pages(&substream->dma_buffer);
+		substream->dma_buffer = new_dmab;
+	} else {
+		buffer->error = -EINVAL;
+	}
+}
+
+/*
+ * pre-allocate the buffer and create a proc file for the substream
+ */
+static int snd_pcm_lib_preallocate_pages1(snd_pcm_substream_t *substream,
+					  size_t size, size_t max)
+{
+	snd_info_entry_t *entry;
+
+	if (size > 0 && preallocate_dma && substream->number < maximum_substreams)
+		preallocate_pcm_pages(substream, size);
+
+	if (substream->dma_buffer.bytes > 0)
+		substream->buffer_bytes_max = substream->dma_buffer.bytes;
+	substream->dma_max = max;
+	if ((entry = snd_info_create_card_entry(substream->pcm->card, "prealloc", substream->proc_root)) != NULL) {
+		entry->c.text.read_size = 64;
+		entry->c.text.read = snd_pcm_lib_preallocate_proc_read;
+		entry->c.text.write_size = 64;
+		entry->c.text.write = snd_pcm_lib_preallocate_proc_write;
+		entry->private_data = substream;
+		if (snd_info_register(entry) < 0) {
+			snd_info_free_entry(entry);
+			entry = NULL;
+		}
+	}
+	substream->proc_prealloc_entry = entry;
+	return 0;
+}
+
+
+/**
+ * snd_pcm_lib_preallocate_pages - pre-allocation for the given DMA type
+ * @substream: the pcm substream instance
+ * @type: DMA type (SNDRV_DMA_TYPE_*)
+ * @data: DMA type dependant data
+ * @size: the requested pre-allocation size in bytes
+ * @max: the max. allowed pre-allocation size
+ *
+ * Do pre-allocation for the given DMA buffer type.
+ *
+ * When substream->dma_buf_id is set, the function tries to look for
+ * the reserved buffer, and the buffer is not freed but reserved at
+ * destruction time.  The dma_buf_id must be unique for all systems
+ * (in the same DMA buffer type) e.g. using snd_dma_pci_buf_id().
+ *
+ * Returns zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_lib_preallocate_pages(snd_pcm_substream_t *substream,
+				  int type, struct device *data,
+				  size_t size, size_t max)
+{
+	substream->dma_buffer.dev.type = type;
+	substream->dma_buffer.dev.dev = data;
+	return snd_pcm_lib_preallocate_pages1(substream, size, max);
+}
+
+/**
+ * snd_pcm_lib_preallocate_pages_for_all - pre-allocation for continous memory type (all substreams)
+ * @substream: the pcm substream instance
+ * @type: DMA type (SNDRV_DMA_TYPE_*)
+ * @data: DMA type dependant data
+ * @size: the requested pre-allocation size in bytes
+ * @max: the max. allowed pre-allocation size
+ *
+ * Do pre-allocation to all substreams of the given pcm for the
+ * specified DMA type.
+ *
+ * Returns zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_lib_preallocate_pages_for_all(snd_pcm_t *pcm,
+					  int type, void *data,
+					  size_t size, size_t max)
+{
+	snd_pcm_substream_t *substream;
+	int stream, err;
+
+	for (stream = 0; stream < 2; stream++)
+		for (substream = pcm->streams[stream].substream; substream; substream = substream->next)
+			if ((err = snd_pcm_lib_preallocate_pages(substream, type, data, size, max)) < 0)
+				return err;
+	return 0;
+}
+
+/**
+ * snd_pcm_sgbuf_ops_page - get the page struct at the given offset
+ * @substream: the pcm substream instance
+ * @offset: the buffer offset
+ *
+ * Returns the page struct at the given buffer offset.
+ * Used as the page callback of PCM ops.
+ */
+struct page *snd_pcm_sgbuf_ops_page(snd_pcm_substream_t *substream, unsigned long offset)
+{
+	struct snd_sg_buf *sgbuf = snd_pcm_substream_sgbuf(substream);
+
+	unsigned int idx = offset >> PAGE_SHIFT;
+	if (idx >= (unsigned int)sgbuf->pages)
+		return NULL;
+	return sgbuf->page_table[idx];
+}
+
+/**
+ * snd_pcm_lib_malloc_pages - allocate the DMA buffer
+ * @substream: the substream to allocate the DMA buffer to
+ * @size: the requested buffer size in bytes
+ *
+ * Allocates the DMA buffer on the BUS type given earlier to
+ * snd_pcm_lib_preallocate_xxx_pages().
+ *
+ * Returns 1 if the buffer is changed, 0 if not changed, or a negative
+ * code on failure.
+ */
+int snd_pcm_lib_malloc_pages(snd_pcm_substream_t *substream, size_t size)
+{
+	snd_pcm_runtime_t *runtime;
+	struct snd_dma_buffer *dmab = NULL;
+
+	snd_assert(substream->dma_buffer.dev.type != SNDRV_DMA_TYPE_UNKNOWN, return -EINVAL);
+	snd_assert(substream != NULL, return -EINVAL);
+	runtime = substream->runtime;
+	snd_assert(runtime != NULL, return -EINVAL);
+
+	if (runtime->dma_buffer_p) {
+		/* perphaps, we might free the large DMA memory region
+		   to save some space here, but the actual solution
+		   costs us less time */
+		if (runtime->dma_buffer_p->bytes >= size) {
+			runtime->dma_bytes = size;
+			return 0;	/* ok, do not change */
+		}
+		snd_pcm_lib_free_pages(substream);
+	}
+	if (substream->dma_buffer.area != NULL && substream->dma_buffer.bytes >= size) {
+		dmab = &substream->dma_buffer; /* use the pre-allocated buffer */
+	} else {
+		dmab = kcalloc(1, sizeof(*dmab), GFP_KERNEL);
+		if (! dmab)
+			return -ENOMEM;
+		dmab->dev = substream->dma_buffer.dev;
+		if (snd_dma_alloc_pages(substream->dma_buffer.dev.type,
+					substream->dma_buffer.dev.dev,
+					size, dmab) < 0) {
+			kfree(dmab);
+			return -ENOMEM;
+		}
+	}
+	snd_pcm_set_runtime_buffer(substream, dmab);
+	runtime->dma_bytes = size;
+	return 1;			/* area was changed */
+}
+
+/**
+ * snd_pcm_lib_free_pages - release the allocated DMA buffer.
+ * @substream: the substream to release the DMA buffer
+ *
+ * Releases the DMA buffer allocated via snd_pcm_lib_malloc_pages().
+ *
+ * Returns zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_lib_free_pages(snd_pcm_substream_t *substream)
+{
+	snd_pcm_runtime_t *runtime;
+
+	snd_assert(substream != NULL, return -EINVAL);
+	runtime = substream->runtime;
+	snd_assert(runtime != NULL, return -EINVAL);
+	if (runtime->dma_area == NULL)
+		return 0;
+	if (runtime->dma_buffer_p != &substream->dma_buffer) {
+		/* it's a newly allocated buffer.  release it now. */
+		snd_dma_free_pages(runtime->dma_buffer_p);
+		kfree(runtime->dma_buffer_p);
+	}
+	snd_pcm_set_runtime_buffer(substream, NULL);
+	return 0;
+}