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- /* SPDX-License-Identifier: GPL-2.0+ */
- /*
- * Generic bounce buffer implementation
- *
- * Copyright (C) 2012 Marek Vasut <marex@denx.de>
- */
- #ifndef __INCLUDE_BOUNCEBUF_H__
- #define __INCLUDE_BOUNCEBUF_H__
- #include <linux/types.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_start() -- Start the bounce buffer session with external align check function
- * 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.
- * alignment: alignment of the newly allocated bounce buffer
- * addr_is_aligned: function for checking the alignment instead of the default one
- */
- int bounce_buffer_start_extalign(struct bounce_buffer *state, void *data,
- size_t len, unsigned int flags,
- size_t alignment,
- int (*addr_is_aligned)(struct bounce_buffer *state));
- /**
- * 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);
- #endif
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