Index: uspace/lib/usbhost/src/dma_buffer.c
===================================================================
--- uspace/lib/usbhost/src/dma_buffer.c	(revision e76c0ea8f951c2e63efa8e948fc849e59dec918b)
+++ uspace/lib/usbhost/src/dma_buffer.c	(revision e76c0ea8f951c2e63efa8e948fc849e59dec918b)
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2013 Jan Vesely
+ * Copyright (c) 2017 Ondrej Hlavaty <aearsis@eideo.cz>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/**  @addtogroup libusbhost
+ * @{
+ */
+/** @file
+ */
+
+#include <usb/host/dma_buffer.h>
+
+#include <align.h>
+#include <as.h>
+#include <ddi.h>
+#include <stddef.h>
+
+dma_policy_t dma_policy_default = {
+	.use64 = false,
+	.alignment = PAGE_SIZE,
+};
+
+/** Allocate a DMA buffer.
+ *
+ * @param[in] db dma_buffer_t structure to fill
+ * @param[in] policy dma_policy_t structure to guide
+ * @param[in] size Size of the required memory space
+ * @return Error code.
+ */
+int dma_buffer_alloc_policy(dma_buffer_t *db, size_t size, dma_policy_t policy)
+{
+	assert(db);
+
+	if (policy.alignment > PAGE_SIZE)
+		return EINVAL;
+
+	const size_t aligned_size = ALIGN_UP(size, policy.alignment);
+	const size_t real_size = ALIGN_UP(aligned_size, PAGE_SIZE);
+	const int flags = policy.use64 ? 0 : DMAMEM_4GiB;
+
+	uintptr_t phys;
+	void *address = AS_AREA_ANY;
+
+	const int ret = dmamem_map_anonymous(real_size,
+	    flags, AS_AREA_READ | AS_AREA_WRITE, 0,
+	    &phys, &address);
+
+	if (ret == EOK) {
+		/* Poison, accessing it should be enough to make sure
+		 * the location is mapped, but poison works better */
+		memset(address, 0x5, real_size);
+		db->virt = address;
+		db->phys = phys;
+	}
+	return ret;
+}
+
+/** Allocate a DMA buffer using the default policy.
+ *
+ * @param[in] db dma_buffer_t structure to fill
+ * @param[in] size Size of the required memory space
+ * @return Error code.
+ */
+int dma_buffer_alloc(dma_buffer_t *db, size_t size)
+{
+	return dma_buffer_alloc_policy(db, size, dma_policy_default);
+}
+
+
+/** Free a DMA buffer.
+ *
+ * @param[in] db dma_buffer_t structure buffer of which will be freed
+ */
+void dma_buffer_free(dma_buffer_t *db)
+{
+	if (db->virt) {
+		dmamem_unmap_anonymous(db->virt);
+		db->virt = NULL;
+		db->phys = 0;
+	}
+}
+
+/**
+ * @}
+ */