common/bouncebuf.c

   1 /*
   2  * Generic bounce buffer implementation
   3  *
   4  * Copyright (C) 2012 Marek Vasut <marex@denx.de>
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #include <common.h>
  10 #include <malloc.h>
  11 #include <errno.h>
  12 #include <bouncebuf.h>
  13
  14 static int addr_aligned(struct bounce_buffer *state)
  15 {
  16         const ulong align_mask = ARCH_DMA_MINALIGN - 1;
  17
  18         /* Check if start is aligned */
  19         if ((ulong)state->user_buffer & align_mask) {
  20                 debug("Unaligned buffer address %p\n", state->user_buffer);
  21                 return 0;
  22         }
  23
  24         /* Check if length is aligned */
  25         if (state->len != state->len_aligned) {
  26                 debug("Unaligned buffer length %zu\n", state->len);
  27                 return 0;
  28         }
  29
  30         /* Aligned */
  31         return 1;
  32 }
  33
  34 int bounce_buffer_start(struct bounce_buffer *state, void *data,
  35                         size_t len, unsigned int flags)
  36 {
  37         state->user_buffer = data;
  38         state->bounce_buffer = data;
  39         state->len = len;
  40         state->len_aligned = roundup(len, ARCH_DMA_MINALIGN);
  41         state->flags = flags;
  42
  43         if (!addr_aligned(state)) {
  44                 state->bounce_buffer = memalign(ARCH_DMA_MINALIGN,
  45                                                 state->len_aligned);
  46                 if (!state->bounce_buffer)
  47                         return -ENOMEM;
  48
  49                 if (state->flags & GEN_BB_READ)
  50                         memcpy(state->bounce_buffer, state->user_buffer,
  51                                 state->len);
  52         }
  53
  54         /*
  55          * Flush data to RAM so DMA reads can pick it up,
  56          * and any CPU writebacks don't race with DMA writes
  57          */
  58         flush_dcache_range((unsigned long)state->bounce_buffer,
  59                                 (unsigned long)(state->bounce_buffer) +
  60                                         state->len_aligned);
  61
  62         return 0;
  63 }
  64
  65 int bounce_buffer_stop(struct bounce_buffer *state)
  66 {
  67         if (state->flags & GEN_BB_WRITE) {
  68                 /* Invalidate cache so that CPU can see any newly DMA'd data */
  69                 invalidate_dcache_range((unsigned long)state->bounce_buffer,
  70                                         (unsigned long)(state->bounce_buffer) +
  71                                                 state->len_aligned);
  72         }
  73
  74         if (state->bounce_buffer == state->user_buffer)
  75                 return 0;
  76
  77         if (state->flags & GEN_BB_WRITE)
  78                 memcpy(state->user_buffer, state->bounce_buffer, state->len);
  79
  80         free(state->bounce_buffer);
  81
  82         return 0;
  83 }