1 | // SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) |
2 | // |
3 | // This file is provided under a dual BSD/GPLv2 license. When using or |
4 | // redistributing this file, you may do so under either license. |
5 | // |
6 | // Copyright(c) 2018-2022 Intel Corporation. All rights reserved. |
7 | // |
8 | // Author: Keyon Jie <yang.jie@linux.intel.com> |
9 | // |
10 | |
11 | #include <asm/unaligned.h> |
12 | #include <linux/io-64-nonatomic-lo-hi.h> |
13 | #include <linux/device.h> |
14 | #include <sound/memalloc.h> |
15 | #include <linux/module.h> |
16 | #include "sof-utils.h" |
17 | |
18 | /* |
19 | * Generic buffer page table creation. |
20 | * Take the each physical page address and drop the least significant unused |
21 | * bits from each (based on PAGE_SIZE). Then pack valid page address bits |
22 | * into compressed page table. |
23 | */ |
24 | |
25 | int snd_sof_create_page_table(struct device *dev, |
26 | struct snd_dma_buffer *dmab, |
27 | unsigned char *page_table, size_t size) |
28 | { |
29 | int i, pages; |
30 | |
31 | pages = snd_sgbuf_aligned_pages(size); |
32 | |
33 | dev_dbg(dev, "generating page table for %p size 0x%zx pages %d\n" , |
34 | dmab->area, size, pages); |
35 | |
36 | for (i = 0; i < pages; i++) { |
37 | /* |
38 | * The number of valid address bits for each page is 20. |
39 | * idx determines the byte position within page_table |
40 | * where the current page's address is stored |
41 | * in the compressed page_table. |
42 | * This can be calculated by multiplying the page number by 2.5. |
43 | */ |
44 | u32 idx = (5 * i) >> 1; |
45 | u32 pfn = snd_sgbuf_get_addr(dmab, offset: i * PAGE_SIZE) >> PAGE_SHIFT; |
46 | u8 *pg_table; |
47 | |
48 | pg_table = (u8 *)(page_table + idx); |
49 | |
50 | /* |
51 | * pagetable compression: |
52 | * byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 |
53 | * ___________pfn 0__________ __________pfn 1___________ _pfn 2... |
54 | * .... .... .... .... .... .... .... .... .... .... .... |
55 | * It is created by: |
56 | * 1. set current location to 0, PFN index i to 0 |
57 | * 2. put pfn[i] at current location in Little Endian byte order |
58 | * 3. calculate an intermediate value as |
59 | * x = (pfn[i+1] << 4) | (pfn[i] & 0xf) |
60 | * 4. put x at offset (current location + 2) in LE byte order |
61 | * 5. increment current location by 5 bytes, increment i by 2 |
62 | * 6. continue to (2) |
63 | */ |
64 | if (i & 1) |
65 | put_unaligned_le32(val: (pg_table[0] & 0xf) | pfn << 4, |
66 | p: pg_table); |
67 | else |
68 | put_unaligned_le32(val: pfn, p: pg_table); |
69 | } |
70 | |
71 | return pages; |
72 | } |
73 | EXPORT_SYMBOL(snd_sof_create_page_table); |
74 | |
75 | MODULE_LICENSE("Dual BSD/GPL" ); |
76 | |