LXR uboot/include/bouncebuf.h

   1/* SPDX-License-Identifier: GPL-2.0+ */
   2/*
   3 * Generic bounce buffer implementation
   4 *
   5 * Copyright (C) 2012 Marek Vasut <marex@denx.de>
   6 */
   7
   8#ifndef __INCLUDE_BOUNCEBUF_H__
   9#define __INCLUDE_BOUNCEBUF_H__
  10
  11#include <linux/types.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
  39struct 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 */
  63int bounce_buffer_start(struct bounce_buffer *state, void *data,
  64                        size_t len, unsigned int flags);
  65
  66/**
  67 * bounce_buffer_start() -- Start the bounce buffer session with external align check function
  68 * state:       stores state passed between bounce_buffer_{start,stop}
  69 * data:        pointer to buffer to be aligned
  70 * len:         length of the buffer
  71 * flags:       flags describing the transaction, see above.
  72 * alignment:   alignment of the newly allocated bounce buffer
  73 * addr_is_aligned: function for checking the alignment instead of the default one
  74 */
  75int bounce_buffer_start_extalign(struct bounce_buffer *state, void *data,
  76                                 size_t len, unsigned int flags,
  77                                 size_t alignment,
  78                                 int (*addr_is_aligned)(struct bounce_buffer *state));
  79
  80/**
  81 * bounce_buffer_stop() -- Finish the bounce buffer session
  82 * state:       stores state passed between bounce_buffer_{start,stop}
  83 */
  84int bounce_buffer_stop(struct bounce_buffer *state);
  85
  86#endif
  87