common/bouncebuf.c

   1 /*
   2  * Generic bounce buffer implementation
   3  *
   4  * Copyright (C) 2012 Marek Vasut <marex@denx.de>
   5  *
   6  * See file CREDITS for list of people who contributed to this
   7  * project.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation; either version 2 of
  12  * the License, or (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  22  * MA 02111-1307 USA
  23  */
  24
  25 #include <common.h>
  26 #include <malloc.h>
  27 #include <errno.h>
  28 #include <bouncebuf.h>
  29
  30 static int addr_aligned(struct bounce_buffer *state)
  31 {
  32         const ulong align_mask = ARCH_DMA_MINALIGN - 1;
  33
  34         /* Check if start is aligned */
  35         if ((ulong)state->user_buffer & align_mask) {
  36                 debug("Unaligned buffer address %p\n", state->user_buffer);
  37                 return 0;
  38         }
  39
  40         /* Check if length is aligned */
  41         if (state->len != state->len_aligned) {
  42                 debug("Unaligned buffer length %d\n", state->len);
  43                 return 0;
  44         }
  45
  46         /* Aligned */
  47         return 1;
  48 }
  49
  50 int bounce_buffer_start(struct bounce_buffer *state, void *data,
  51                         size_t len, unsigned int flags)
  52 {
  53         state->user_buffer = data;
  54         state->bounce_buffer = data;
  55         state->len = len;
  56         state->len_aligned = roundup(len, ARCH_DMA_MINALIGN);
  57         state->flags = flags;
  58
  59         if (!addr_aligned(state)) {
  60                 state->bounce_buffer = memalign(ARCH_DMA_MINALIGN,
  61                                                 state->len_aligned);
  62                 if (!state->bounce_buffer)
  63                         return -ENOMEM;
  64
  65                 if (state->flags & GEN_BB_READ)
  66                         memcpy(state->bounce_buffer, state->user_buffer,
  67                                 state->len);
  68         }
  69
  70         /*
  71          * Flush data to RAM so DMA reads can pick it up,
  72          * and any CPU writebacks don't race with DMA writes
  73          */
  74         flush_dcache_range((unsigned long)state->bounce_buffer,
  75                                 (unsigned long)(state->bounce_buffer) +
  76                                         state->len_aligned);
  77
  78         return 0;
  79 }
  80
  81 int bounce_buffer_stop(struct bounce_buffer *state)
  82 {
  83         if (state->flags & GEN_BB_WRITE) {
  84                 /* Invalidate cache so that CPU can see any newly DMA'd data */
  85                 invalidate_dcache_range((unsigned long)state->bounce_buffer,
  86                                         (unsigned long)(state->bounce_buffer) +
  87                                                 state->len_aligned);
  88         }
  89
  90         if (state->bounce_buffer == state->user_buffer)
  91                 return 0;
  92
  93         if (state->flags & GEN_BB_WRITE)
  94                 memcpy(state->user_buffer, state->bounce_buffer, state->len);
  95
  96         free(state->bounce_buffer);
  97
  98         return 0;
  99 }