88 lines
3.1 KiB
C
88 lines
3.1 KiB
C
/*
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* Generic bounce buffer implementation
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*
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* Copyright (C) 2012 Marek Vasut <marex@denx.de>
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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#ifndef __INCLUDE_BOUNCEBUF_H__
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#define __INCLUDE_BOUNCEBUF_H__
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/*
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* GEN_BB_READ -- Data are read from the buffer eg. by DMA hardware.
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* The source buffer is copied into the bounce buffer (if unaligned, otherwise
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* the source buffer is used directly) upon start() call, then the operation
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* requiring the aligned transfer happens, then the bounce buffer is lost upon
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* stop() call.
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*/
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#define GEN_BB_READ (1 << 0)
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/*
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* GEN_BB_WRITE -- Data are written into the buffer eg. by DMA hardware.
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* The source buffer starts in an undefined state upon start() call, then the
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* operation requiring the aligned transfer happens, then the bounce buffer is
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* copied into the destination buffer (if unaligned, otherwise destination
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* buffer is used directly) upon stop() call.
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*/
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#define GEN_BB_WRITE (1 << 1)
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/*
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* GEN_BB_RW -- Data are read and written into the buffer eg. by DMA hardware.
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* The source buffer is copied into the bounce buffer (if unaligned, otherwise
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* the source buffer is used directly) upon start() call, then the operation
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* requiring the aligned transfer happens, then the bounce buffer is copied
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* into the destination buffer (if unaligned, otherwise destination buffer is
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* used directly) upon stop() call.
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*/
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#define GEN_BB_RW (GEN_BB_READ | GEN_BB_WRITE)
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#ifdef CONFIG_BOUNCE_BUFFER
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/**
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* bounce_buffer_start() -- Start the bounce buffer session
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* data: pointer to buffer to be aligned
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* len: length of the buffer
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* backup: pointer to backup buffer (the original value is stored here if
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* needed
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* flags: flags describing the transaction, see above.
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*/
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int bounce_buffer_start(void **data, size_t len, void **backup, uint8_t flags);
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/**
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* bounce_buffer_stop() -- Finish the bounce buffer session
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* data: pointer to buffer that was aligned
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* len: length of the buffer
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* backup: pointer to backup buffer (the original value is stored here if
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* needed
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* flags: flags describing the transaction, see above.
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*/
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int bounce_buffer_stop(void **data, size_t len, void **backup, uint8_t flags);
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#else
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static inline int bounce_buffer_start(void **data, size_t len, void **backup,
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uint8_t flags)
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{
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return 0;
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}
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static inline int bounce_buffer_stop(void **data, size_t len, void **backup,
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uint8_t flags)
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{
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return 0;
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}
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#endif
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#endif
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