1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * Generic bounce buffer implementation 4 */ 5 6 #ifndef __COMMONLIB_STORAGE_BOUNCEBUF_H__ 7 #define __COMMONLIB_STORAGE_BOUNCEBUF_H__ 8 9 #include <stddef.h> 10 #include <stdint.h> 11 #include <stdlib.h> 12 13 /* 14 * GEN_BB_READ -- Data are read from the buffer eg. by DMA hardware. 15 * The source buffer is copied into the bounce buffer (if unaligned, otherwise 16 * the source buffer is used directly) upon start() call, then the operation 17 * requiring the aligned transfer happens, then the bounce buffer is lost upon 18 * stop() call. 19 */ 20 #define GEN_BB_READ (1 << 0) 21 /* 22 * GEN_BB_WRITE -- Data are written into the buffer eg. by DMA hardware. 23 * The source buffer starts in an undefined state upon start() call, then the 24 * operation requiring the aligned transfer happens, then the bounce buffer is 25 * copied into the destination buffer (if unaligned, otherwise destination 26 * buffer is used directly) upon stop() call. 27 */ 28 #define GEN_BB_WRITE (1 << 1) 29 /* 30 * GEN_BB_RW -- Data are read and written into the buffer eg. by DMA hardware. 31 * The source buffer is copied into the bounce buffer (if unaligned, otherwise 32 * the source buffer is used directly) upon start() call, then the operation 33 * requiring the aligned transfer happens, then the bounce buffer is copied 34 * into the destination buffer (if unaligned, otherwise destination buffer is 35 * used directly) upon stop() call. 36 */ 37 #define GEN_BB_RW (GEN_BB_READ | GEN_BB_WRITE) 38 39 struct bounce_buffer { 40 /* Copy of data parameter passed to start() */ 41 void *user_buffer; 42 /* 43 * DMA-aligned buffer. This field is always set to the value that 44 * should be used for DMA; either equal to .user_buffer, or to a 45 * freshly allocated aligned buffer. 46 */ 47 void *bounce_buffer; 48 /* Copy of len parameter passed to start() */ 49 size_t len; 50 /* DMA-aligned buffer length */ 51 size_t len_aligned; 52 /* Copy of flags parameter passed to start() */ 53 unsigned int flags; 54 }; 55 56 /** 57 * bounce_buffer_start() -- Start the bounce buffer session 58 * state: stores state passed between bounce_buffer_{start,stop} 59 * data: pointer to buffer to be aligned 60 * len: length of the buffer 61 * flags: flags describing the transaction, see above. 62 */ 63 int bounce_buffer_start(struct bounce_buffer *state, void *data, 64 size_t len, unsigned int flags); 65 /** 66 * bounce_buffer_stop() -- Finish the bounce buffer session 67 * state: stores state passed between bounce_buffer_{start,stop} 68 */ 69 int bounce_buffer_stop(struct bounce_buffer *state); 70 71 // TODO(hungte) Eliminate the alignment stuff below and replace them with a 72 // better and centralized way to handler non-cache/aligned memory. 73 // Helper macros for alignment. 74 #define DMA_MINALIGN (64) 75 #define ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1)) 76 #define ALLOC_CACHE_ALIGN_BUFFER(type, name, size) \ 77 char __##name[ROUND(size * sizeof(type), DMA_MINALIGN) + \ 78 DMA_MINALIGN - 1]; \ 79 type *name = (type *)ALIGN_UP((uintptr_t)__##name, DMA_MINALIGN) 80 #ifndef ARCH_DMA_MINALIGN 81 #define ARCH_DMA_MINALIGN (DMA_MINALIGN) 82 #endif 83 84 #endif // __COMMONLIB_STORAGE_BOUNCEBUF_H__ 85