summaryrefslogtreecommitdiff
path: root/src/drivers/storage/bouncebuf.h
diff options
context:
space:
mode:
Diffstat (limited to 'src/drivers/storage/bouncebuf.h')
-rw-r--r--src/drivers/storage/bouncebuf.h96
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
index 0000000000..deea4f8636
--- /dev/null
+++ b/src/drivers/storage/bouncebuf.h
@@ -0,0 +1,96 @@
+/*
+ * 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__