From b660df3c9031ba2efded2d083c34f2ea5ff978ff Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Sun, 26 Aug 2012 15:19:06 +0000 Subject: COMMON: Implement common bounce buffer Implement common bounce buffer to be used on a less capable hardware. That includes hardware that can not do DMA from any address or such. Signed-off-by: Marek Vasut Cc: Fabio Estevam Cc: Andy Fleming Signed-off-by: Andy Fleming --- include/bouncebuf.h | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 include/bouncebuf.h (limited to 'include/bouncebuf.h') diff --git a/include/bouncebuf.h b/include/bouncebuf.h new file mode 100644 index 0000000000..31021c5b85 --- /dev/null +++ b/include/bouncebuf.h @@ -0,0 +1,87 @@ +/* + * Generic bounce buffer implementation + * + * Copyright (C) 2012 Marek Vasut + * + * 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 -- cgit v1.2.3