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b660df3c MV |
1 | /* |
2 | * Generic bounce buffer implementation | |
3 | * | |
4 | * Copyright (C) 2012 Marek Vasut <[email protected]> | |
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 | ||
84d35b28 SW |
28 | #include <linux/types.h> |
29 | ||
b660df3c MV |
30 | /* |
31 | * GEN_BB_READ -- Data are read from the buffer eg. by DMA hardware. | |
32 | * The source buffer is copied into the bounce buffer (if unaligned, otherwise | |
33 | * the source buffer is used directly) upon start() call, then the operation | |
34 | * requiring the aligned transfer happens, then the bounce buffer is lost upon | |
35 | * stop() call. | |
36 | */ | |
37 | #define GEN_BB_READ (1 << 0) | |
38 | /* | |
39 | * GEN_BB_WRITE -- Data are written into the buffer eg. by DMA hardware. | |
40 | * The source buffer starts in an undefined state upon start() call, then the | |
41 | * operation requiring the aligned transfer happens, then the bounce buffer is | |
42 | * copied into the destination buffer (if unaligned, otherwise destination | |
43 | * buffer is used directly) upon stop() call. | |
44 | */ | |
45 | #define GEN_BB_WRITE (1 << 1) | |
46 | /* | |
47 | * GEN_BB_RW -- Data are read and written into the buffer eg. by DMA hardware. | |
48 | * The source buffer is copied into the bounce buffer (if unaligned, otherwise | |
49 | * the source buffer is used directly) upon start() call, then the operation | |
50 | * requiring the aligned transfer happens, then the bounce buffer is copied | |
51 | * into the destination buffer (if unaligned, otherwise destination buffer is | |
52 | * used directly) upon stop() call. | |
53 | */ | |
54 | #define GEN_BB_RW (GEN_BB_READ | GEN_BB_WRITE) | |
55 | ||
84d35b28 SW |
56 | struct bounce_buffer { |
57 | /* Copy of data parameter passed to start() */ | |
58 | void *user_buffer; | |
59 | /* | |
60 | * DMA-aligned buffer. This field is always set to the value that | |
61 | * should be used for DMA; either equal to .user_buffer, or to a | |
62 | * freshly allocated aligned buffer. | |
63 | */ | |
64 | void *bounce_buffer; | |
65 | /* Copy of len parameter passed to start() */ | |
66 | size_t len; | |
67 | /* DMA-aligned buffer length */ | |
68 | size_t len_aligned; | |
69 | /* Copy of flags parameter passed to start() */ | |
70 | unsigned int flags; | |
71 | }; | |
72 | ||
b660df3c MV |
73 | /** |
74 | * bounce_buffer_start() -- Start the bounce buffer session | |
84d35b28 | 75 | * state: stores state passed between bounce_buffer_{start,stop} |
b660df3c MV |
76 | * data: pointer to buffer to be aligned |
77 | * len: length of the buffer | |
b660df3c MV |
78 | * flags: flags describing the transaction, see above. |
79 | */ | |
84d35b28 SW |
80 | int bounce_buffer_start(struct bounce_buffer *state, void *data, |
81 | size_t len, unsigned int flags); | |
b660df3c MV |
82 | /** |
83 | * bounce_buffer_stop() -- Finish the bounce buffer session | |
84d35b28 | 84 | * state: stores state passed between bounce_buffer_{start,stop} |
b660df3c | 85 | */ |
84d35b28 | 86 | int bounce_buffer_stop(struct bounce_buffer *state); |
b660df3c MV |
87 | |
88 | #endif |