1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Generic bounce buffer implementation
4 *
5 * Copyright (C) 2012 Marek Vasut <marex@denx.de>
6 */
7
8 #include <common.h>
9 #include <cpu_func.h>
10 #include <malloc.h>
11 #include <errno.h>
12 #include <bouncebuf.h>
13
addr_aligned(struct bounce_buffer * state)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
bounce_buffer_start(struct bounce_buffer * state,void * data,size_t len,unsigned int flags)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
bounce_buffer_stop(struct bounce_buffer * state)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 }
84