| /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| /* |
| * Generic bounce buffer implementation |
| */ |
| |
| #ifndef __COMMONLIB_STORAGE_BOUNCEBUF_H__ |
| #define __COMMONLIB_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_UP((uintptr_t)__##name, DMA_MINALIGN) |
| #ifndef ARCH_DMA_MINALIGN |
| #define ARCH_DMA_MINALIGN (DMA_MINALIGN) |
| #endif |
| |
| #endif // __COMMONLIB_STORAGE_BOUNCEBUF_H__ |