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29fb44a5 HV |
1 | /* |
2 | * cec-edid - HDMI Consumer Electronics Control EDID & CEC helper functions | |
3 | * | |
4 | * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights reserved. | |
5 | * | |
6 | * This program is free software; you may redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; version 2 of the License. | |
9 | * | |
10 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
11 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF | |
12 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
13 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS | |
14 | * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN | |
15 | * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | |
16 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
17 | * SOFTWARE. | |
18 | */ | |
19 | ||
20 | #include <linux/module.h> | |
21 | #include <linux/kernel.h> | |
22 | #include <linux/types.h> | |
23 | #include <media/cec-edid.h> | |
24 | ||
25 | /* | |
26 | * This EDID is expected to be a CEA-861 compliant, which means that there are | |
27 | * at least two blocks and one or more of the extensions blocks are CEA-861 | |
28 | * blocks. | |
29 | * | |
30 | * The returned location is guaranteed to be < size - 1. | |
31 | */ | |
32 | static unsigned int cec_get_edid_spa_location(const u8 *edid, unsigned int size) | |
33 | { | |
34 | unsigned int blocks = size / 128; | |
35 | unsigned int block; | |
36 | u8 d; | |
37 | ||
38 | /* Sanity check: at least 2 blocks and a multiple of the block size */ | |
39 | if (blocks < 2 || size % 128) | |
40 | return 0; | |
41 | ||
42 | /* | |
43 | * If there are fewer extension blocks than the size, then update | |
44 | * 'blocks'. It is allowed to have more extension blocks than the size, | |
45 | * since some hardware can only read e.g. 256 bytes of the EDID, even | |
46 | * though more blocks are present. The first CEA-861 extension block | |
47 | * should normally be in block 1 anyway. | |
48 | */ | |
49 | if (edid[0x7e] + 1 < blocks) | |
50 | blocks = edid[0x7e] + 1; | |
51 | ||
52 | for (block = 1; block < blocks; block++) { | |
53 | unsigned int offset = block * 128; | |
54 | ||
55 | /* Skip any non-CEA-861 extension blocks */ | |
56 | if (edid[offset] != 0x02 || edid[offset + 1] != 0x03) | |
57 | continue; | |
58 | ||
59 | /* search Vendor Specific Data Block (tag 3) */ | |
60 | d = edid[offset + 2] & 0x7f; | |
61 | /* Check if there are Data Blocks */ | |
62 | if (d <= 4) | |
63 | continue; | |
64 | if (d > 4) { | |
65 | unsigned int i = offset + 4; | |
66 | unsigned int end = offset + d; | |
67 | ||
68 | /* Note: 'end' is always < 'size' */ | |
69 | do { | |
70 | u8 tag = edid[i] >> 5; | |
71 | u8 len = edid[i] & 0x1f; | |
72 | ||
8ac6a1a5 HV |
73 | if (tag == 3 && len >= 5 && i + len <= end && |
74 | edid[i + 1] == 0x03 && | |
75 | edid[i + 2] == 0x0c && | |
76 | edid[i + 3] == 0x00) | |
29fb44a5 HV |
77 | return i + 4; |
78 | i += len + 1; | |
79 | } while (i < end); | |
80 | } | |
81 | } | |
82 | return 0; | |
83 | } | |
84 | ||
85 | u16 cec_get_edid_phys_addr(const u8 *edid, unsigned int size, | |
86 | unsigned int *offset) | |
87 | { | |
88 | unsigned int loc = cec_get_edid_spa_location(edid, size); | |
89 | ||
90 | if (offset) | |
91 | *offset = loc; | |
92 | if (loc == 0) | |
93 | return CEC_PHYS_ADDR_INVALID; | |
94 | return (edid[loc] << 8) | edid[loc + 1]; | |
95 | } | |
96 | EXPORT_SYMBOL_GPL(cec_get_edid_phys_addr); | |
97 | ||
98 | void cec_set_edid_phys_addr(u8 *edid, unsigned int size, u16 phys_addr) | |
99 | { | |
100 | unsigned int loc = cec_get_edid_spa_location(edid, size); | |
101 | u8 sum = 0; | |
102 | unsigned int i; | |
103 | ||
104 | if (loc == 0) | |
105 | return; | |
106 | edid[loc] = phys_addr >> 8; | |
107 | edid[loc + 1] = phys_addr & 0xff; | |
108 | loc &= ~0x7f; | |
109 | ||
110 | /* update the checksum */ | |
111 | for (i = loc; i < loc + 127; i++) | |
112 | sum += edid[i]; | |
113 | edid[i] = 256 - sum; | |
114 | } | |
115 | EXPORT_SYMBOL_GPL(cec_set_edid_phys_addr); | |
116 | ||
117 | u16 cec_phys_addr_for_input(u16 phys_addr, u8 input) | |
118 | { | |
119 | /* Check if input is sane */ | |
120 | if (WARN_ON(input == 0 || input > 0xf)) | |
121 | return CEC_PHYS_ADDR_INVALID; | |
122 | ||
123 | if (phys_addr == 0) | |
124 | return input << 12; | |
125 | ||
126 | if ((phys_addr & 0x0fff) == 0) | |
127 | return phys_addr | (input << 8); | |
128 | ||
129 | if ((phys_addr & 0x00ff) == 0) | |
130 | return phys_addr | (input << 4); | |
131 | ||
132 | if ((phys_addr & 0x000f) == 0) | |
133 | return phys_addr | input; | |
134 | ||
135 | /* | |
136 | * All nibbles are used so no valid physical addresses can be assigned | |
137 | * to the input. | |
138 | */ | |
139 | return CEC_PHYS_ADDR_INVALID; | |
140 | } | |
141 | EXPORT_SYMBOL_GPL(cec_phys_addr_for_input); | |
142 | ||
143 | int cec_phys_addr_validate(u16 phys_addr, u16 *parent, u16 *port) | |
144 | { | |
145 | int i; | |
146 | ||
147 | if (parent) | |
148 | *parent = phys_addr; | |
149 | if (port) | |
150 | *port = 0; | |
151 | if (phys_addr == CEC_PHYS_ADDR_INVALID) | |
152 | return 0; | |
153 | for (i = 0; i < 16; i += 4) | |
154 | if (phys_addr & (0xf << i)) | |
155 | break; | |
156 | if (i == 16) | |
157 | return 0; | |
158 | if (parent) | |
159 | *parent = phys_addr & (0xfff0 << i); | |
160 | if (port) | |
161 | *port = (phys_addr >> i) & 0xf; | |
162 | for (i += 4; i < 16; i += 4) | |
163 | if ((phys_addr & (0xf << i)) == 0) | |
164 | return -EINVAL; | |
165 | return 0; | |
166 | } | |
167 | EXPORT_SYMBOL_GPL(cec_phys_addr_validate); | |
168 | ||
169 | MODULE_AUTHOR("Hans Verkuil <hans.verkuil@cisco.com>"); | |
170 | MODULE_DESCRIPTION("CEC EDID helper functions"); | |
171 | MODULE_LICENSE("GPL"); |