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/*
* Generic bounce buffer implementation
*
* Copyright (C) 2012 Marek Vasut <marex@denx.de>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <common.h>
#include <malloc.h>
#include <errno.h>
#include <bouncebuf.h>
static int addr_aligned(struct bounce_buffer *state)
{
const ulong align_mask = ARCH_DMA_MINALIGN - 1;
/* Check if start is aligned */
if ((ulong)state->user_buffer & align_mask) {
debug("Unaligned buffer address %p\n", state->user_buffer);
return 0;
}
/* Check if length is aligned */
if (state->len != state->len_aligned) {
debug("Unaligned buffer length %d\n", state->len);
return 0;
}
/* Aligned */
return 1;
}
int bounce_buffer_start(struct bounce_buffer *state, void *data,
size_t len, unsigned int flags)
{
state->user_buffer = data;
state->bounce_buffer = data;
state->len = len;
state->len_aligned = roundup(len, ARCH_DMA_MINALIGN);
state->flags = flags;
if (!addr_aligned(state)) {
state->bounce_buffer = memalign(ARCH_DMA_MINALIGN,
state->len_aligned);
if (!state->bounce_buffer)
return -ENOMEM;
if (state->flags & GEN_BB_READ)
memcpy(state->bounce_buffer, state->user_buffer,
state->len);
}
/*
* Flush data to RAM so DMA reads can pick it up,
* and any CPU writebacks don't race with DMA writes
*/
flush_dcache_range((unsigned long)state->bounce_buffer,
(unsigned long)(state->bounce_buffer) +
state->len_aligned);
return 0;
}
int bounce_buffer_stop(struct bounce_buffer *state)
{
if (state->flags & GEN_BB_WRITE) {
/* Invalidate cache so that CPU can see any newly DMA'd data */
invalidate_dcache_range((unsigned long)state->bounce_buffer,
(unsigned long)(state->bounce_buffer) +
state->len_aligned);
}
if (state->bounce_buffer == state->user_buffer)
return 0;
if (state->flags & GEN_BB_WRITE)
memcpy(state->user_buffer, state->bounce_buffer, state->len);
free(state->bounce_buffer);
return 0;
}
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