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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
*/
#ifndef __INCLUDE_BOUNCEBUF_H__
#define __INCLUDE_BOUNCEBUF_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)
#ifdef CONFIG_BOUNCE_BUFFER
/**
* bounce_buffer_start() -- Start the bounce buffer session
* data: pointer to buffer to be aligned
* len: length of the buffer
* backup: pointer to backup buffer (the original value is stored here if
* needed
* flags: flags describing the transaction, see above.
*/
int bounce_buffer_start(void **data, size_t len, void **backup, uint8_t flags);
/**
* bounce_buffer_stop() -- Finish the bounce buffer session
* data: pointer to buffer that was aligned
* len: length of the buffer
* backup: pointer to backup buffer (the original value is stored here if
* needed
* flags: flags describing the transaction, see above.
*/
int bounce_buffer_stop(void **data, size_t len, void **backup, uint8_t flags);
#else
static inline int bounce_buffer_start(void **data, size_t len, void **backup,
uint8_t flags)
{
return 0;
}
static inline int bounce_buffer_stop(void **data, size_t len, void **backup,
uint8_t flags)
{
return 0;
}
#endif
#endif
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