1 files changed, 96 insertions, 0 deletions
diff --git a/src/drivers/storage/bouncebuf.h b/src/drivers/storage/bouncebuf.h
new file mode 100644
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+++ b/src/drivers/storage/bouncebuf.h
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+/*
+ * Generic bounce buffer implementation
+ *
+ * Copyright (C) 2012 Marek Vasut <marex@denx.de>
+ * Copyright 2013 Google Inc.  All rights reserved.
+ *
+ * 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.
+ */
+
+#ifndef __DRIVERS_STORAGE_BOUNCEBUF_H__
+#define __DRIVERS_STORAGE_BOUNCEBUF_H__
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/*
+ * GEN_BB_READ -- Data are read from the buffer eg. by DMA hardware.
+ * The source buffer is copied into the bounce buffer (if unaligned, otherwise
+ * the source buffer is used directly) upon start() call, then the operation
+ * requiring the aligned transfer happens, then the bounce buffer is lost upon
+ * stop() call.
+ */
+#define GEN_BB_READ	(1 << 0)
+/*
+ * GEN_BB_WRITE -- Data are written into the buffer eg. by DMA hardware.
+ * The source buffer starts in an undefined state upon start() call, then the
+ * operation requiring the aligned transfer happens, then the bounce buffer is
+ * copied into the destination buffer (if unaligned, otherwise destination
+ * buffer is used directly) upon stop() call.
+ */
+#define GEN_BB_WRITE	(1 << 1)
+/*
+ * GEN_BB_RW -- Data are read and written into the buffer eg. by DMA hardware.
+ * The source buffer is copied into the bounce buffer (if unaligned, otherwise
+ * the source buffer is used directly) upon start() call, then the  operation
+ * requiring the aligned transfer happens, then the bounce buffer is  copied
+ * into the destination buffer (if unaligned, otherwise destination buffer is
+ * used directly) upon stop() call.
+ */
+#define GEN_BB_RW	(GEN_BB_READ | GEN_BB_WRITE)
+
+struct bounce_buffer {
+	/* Copy of data parameter passed to start() */
+	void *user_buffer;
+	/*
+	 * DMA-aligned buffer. This field is always set to the value that
+	 * should be used for DMA; either equal to .user_buffer, or to a
+	 * freshly allocated aligned buffer.
+	 */
+	void *bounce_buffer;
+	/* Copy of len parameter passed to start() */
+	size_t len;
+	/* DMA-aligned buffer length */
+	size_t len_aligned;
+	/* Copy of flags parameter passed to start() */
+	unsigned int flags;
+};
+
+/**
+ * bounce_buffer_start() -- Start the bounce buffer session
+ * state:	stores state passed between bounce_buffer_{start,stop}
+ * data:	pointer to buffer to be aligned
+ * len:		length of the buffer
+ * flags:	flags describing the transaction, see above.
+ */
+int bounce_buffer_start(struct bounce_buffer *state, void *data,
+			size_t len, unsigned int flags);
+/**
+ * bounce_buffer_stop() -- Finish the bounce buffer session
+ * state:	stores state passed between bounce_buffer_{start,stop}
+ */
+int bounce_buffer_stop(struct bounce_buffer *state);
+
+// TODO(hungte) Eliminate the alignment stuff below and replace them with a
+// better and centralized way to handler non-cache/aligned memory.
+// Helper macros for alignment.
+#define DMA_MINALIGN (64)
+#define ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1))
+#define ALLOC_CACHE_ALIGN_BUFFER(type, name, size)                   \
+	char __##name[ROUND(size * sizeof(type), DMA_MINALIGN) +     \
+		      DMA_MINALIGN - 1];                             \
+	type *name = (type *) ALIGN((uintptr_t)__##name, DMA_MINALIGN)
+#ifndef ARCH_DMA_MINALIGN
+#define ARCH_DMA_MINALIGN (DMA_MINALIGN)
+#endif
+
+#endif // __DRIVERS_STORAGE_BOUNCEBUF_H__