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 #ifndef __INCLUDE_BOUNCEBUF_H__ 26 #define __INCLUDE_BOUNCEBUF_H__ 27 28 /* 29 * GEN_BB_READ -- Data are read from the buffer eg. by DMA hardware. 30 * The source buffer is copied into the bounce buffer (if unaligned, otherwise 31 * the source buffer is used directly) upon start() call, then the operation 32 * requiring the aligned transfer happens, then the bounce buffer is lost upon 33 * stop() call. 34 */ 35 #define GEN_BB_READ (1 << 0) 36 /* 37 * GEN_BB_WRITE -- Data are written into the buffer eg. by DMA hardware. 38 * The source buffer starts in an undefined state upon start() call, then the 39 * operation requiring the aligned transfer happens, then the bounce buffer is 40 * copied into the destination buffer (if unaligned, otherwise destination 41 * buffer is used directly) upon stop() call. 42 */ 43 #define GEN_BB_WRITE (1 << 1) 44 /* 45 * GEN_BB_RW -- Data are read and written into the buffer eg. by DMA hardware. 46 * The source buffer is copied into the bounce buffer (if unaligned, otherwise 47 * the source buffer is used directly) upon start() call, then the operation 48 * requiring the aligned transfer happens, then the bounce buffer is copied 49 * into the destination buffer (if unaligned, otherwise destination buffer is 50 * used directly) upon stop() call. 51 */ 52 #define GEN_BB_RW (GEN_BB_READ | GEN_BB_WRITE) 53 54 #ifdef CONFIG_BOUNCE_BUFFER 55 /** 56 * bounce_buffer_start() -- Start the bounce buffer session 57 * data: pointer to buffer to be aligned 58 * len: length of the buffer 59 * backup: pointer to backup buffer (the original value is stored here if 60 * needed 61 * flags: flags describing the transaction, see above. 62 */ 63 int bounce_buffer_start(void **data, size_t len, void **backup, uint8_t flags); 64 /** 65 * bounce_buffer_stop() -- Finish the bounce buffer session 66 * data: pointer to buffer that was aligned 67 * len: length of the buffer 68 * backup: pointer to backup buffer (the original value is stored here if 69 * needed 70 * flags: flags describing the transaction, see above. 71 */ 72 int bounce_buffer_stop(void **data, size_t len, void **backup, uint8_t flags); 73 #else 74 static inline int bounce_buffer_start(void **data, size_t len, void **backup, 75 uint8_t flags) 76 { 77 return 0; 78 } 79 80 static inline int bounce_buffer_stop(void **data, size_t len, void **backup, 81 uint8_t flags) 82 { 83 return 0; 84 } 85 #endif 86 87 #endif 88