/* 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__