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[u-boot] / common / bouncebuf.c
1 /*
2  * Generic bounce buffer implementation
3  *
4  * Copyright (C) 2012 Marek Vasut <marex@denx.de>
5  *
6  * SPDX-License-Identifier:     GPL-2.0+
7  */
8
9 #include <common.h>
10 #include <malloc.h>
11 #include <errno.h>
12 #include <bouncebuf.h>
13
14 static int addr_aligned(struct bounce_buffer *state)
15 {
16         const ulong align_mask = ARCH_DMA_MINALIGN - 1;
17
18         /* Check if start is aligned */
19         if ((ulong)state->user_buffer & align_mask) {
20                 debug("Unaligned buffer address %p\n", state->user_buffer);
21                 return 0;
22         }
23
24         /* Check if length is aligned */
25         if (state->len != state->len_aligned) {
26                 debug("Unaligned buffer length %zu\n", state->len);
27                 return 0;
28         }
29
30         /* Aligned */
31         return 1;
32 }
33
34 int bounce_buffer_start(struct bounce_buffer *state, void *data,
35                         size_t len, unsigned int flags)
36 {
37         state->user_buffer = data;
38         state->bounce_buffer = data;
39         state->len = len;
40         state->len_aligned = roundup(len, ARCH_DMA_MINALIGN);
41         state->flags = flags;
42
43         if (!addr_aligned(state)) {
44                 state->bounce_buffer = memalign(ARCH_DMA_MINALIGN,
45                                                 state->len_aligned);
46                 if (!state->bounce_buffer)
47                         return -ENOMEM;
48
49                 if (state->flags & GEN_BB_READ)
50                         memcpy(state->bounce_buffer, state->user_buffer,
51                                 state->len);
52         }
53
54         /*
55          * Flush data to RAM so DMA reads can pick it up,
56          * and any CPU writebacks don't race with DMA writes
57          */
58         flush_dcache_range((unsigned long)state->bounce_buffer,
59                                 (unsigned long)(state->bounce_buffer) +
60                                         state->len_aligned);
61
62         return 0;
63 }
64
65 int bounce_buffer_stop(struct bounce_buffer *state)
66 {
67         if (state->flags & GEN_BB_WRITE) {
68                 /* Invalidate cache so that CPU can see any newly DMA'd data */
69                 invalidate_dcache_range((unsigned long)state->bounce_buffer,
70                                         (unsigned long)(state->bounce_buffer) +
71                                                 state->len_aligned);
72         }
73
74         if (state->bounce_buffer == state->user_buffer)
75                 return 0;
76
77         if (state->flags & GEN_BB_WRITE)
78                 memcpy(state->user_buffer, state->bounce_buffer, state->len);
79
80         free(state->bounce_buffer);
81
82         return 0;
83 }