Hans Verkuil | 29fb44a | 2016-06-17 09:13:08 -0300 | [diff] [blame] | 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 | |
| 73 | if (tag == 3 && len >= 5 && i + len <= end) |
| 74 | return i + 4; |
| 75 | i += len + 1; |
| 76 | } while (i < end); |
| 77 | } |
| 78 | } |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | u16 cec_get_edid_phys_addr(const u8 *edid, unsigned int size, |
| 83 | unsigned int *offset) |
| 84 | { |
| 85 | unsigned int loc = cec_get_edid_spa_location(edid, size); |
| 86 | |
| 87 | if (offset) |
| 88 | *offset = loc; |
| 89 | if (loc == 0) |
| 90 | return CEC_PHYS_ADDR_INVALID; |
| 91 | return (edid[loc] << 8) | edid[loc + 1]; |
| 92 | } |
| 93 | EXPORT_SYMBOL_GPL(cec_get_edid_phys_addr); |
| 94 | |
| 95 | void cec_set_edid_phys_addr(u8 *edid, unsigned int size, u16 phys_addr) |
| 96 | { |
| 97 | unsigned int loc = cec_get_edid_spa_location(edid, size); |
| 98 | u8 sum = 0; |
| 99 | unsigned int i; |
| 100 | |
| 101 | if (loc == 0) |
| 102 | return; |
| 103 | edid[loc] = phys_addr >> 8; |
| 104 | edid[loc + 1] = phys_addr & 0xff; |
| 105 | loc &= ~0x7f; |
| 106 | |
| 107 | /* update the checksum */ |
| 108 | for (i = loc; i < loc + 127; i++) |
| 109 | sum += edid[i]; |
| 110 | edid[i] = 256 - sum; |
| 111 | } |
| 112 | EXPORT_SYMBOL_GPL(cec_set_edid_phys_addr); |
| 113 | |
| 114 | u16 cec_phys_addr_for_input(u16 phys_addr, u8 input) |
| 115 | { |
| 116 | /* Check if input is sane */ |
| 117 | if (WARN_ON(input == 0 || input > 0xf)) |
| 118 | return CEC_PHYS_ADDR_INVALID; |
| 119 | |
| 120 | if (phys_addr == 0) |
| 121 | return input << 12; |
| 122 | |
| 123 | if ((phys_addr & 0x0fff) == 0) |
| 124 | return phys_addr | (input << 8); |
| 125 | |
| 126 | if ((phys_addr & 0x00ff) == 0) |
| 127 | return phys_addr | (input << 4); |
| 128 | |
| 129 | if ((phys_addr & 0x000f) == 0) |
| 130 | return phys_addr | input; |
| 131 | |
| 132 | /* |
| 133 | * All nibbles are used so no valid physical addresses can be assigned |
| 134 | * to the input. |
| 135 | */ |
| 136 | return CEC_PHYS_ADDR_INVALID; |
| 137 | } |
| 138 | EXPORT_SYMBOL_GPL(cec_phys_addr_for_input); |
| 139 | |
| 140 | int cec_phys_addr_validate(u16 phys_addr, u16 *parent, u16 *port) |
| 141 | { |
| 142 | int i; |
| 143 | |
| 144 | if (parent) |
| 145 | *parent = phys_addr; |
| 146 | if (port) |
| 147 | *port = 0; |
| 148 | if (phys_addr == CEC_PHYS_ADDR_INVALID) |
| 149 | return 0; |
| 150 | for (i = 0; i < 16; i += 4) |
| 151 | if (phys_addr & (0xf << i)) |
| 152 | break; |
| 153 | if (i == 16) |
| 154 | return 0; |
| 155 | if (parent) |
| 156 | *parent = phys_addr & (0xfff0 << i); |
| 157 | if (port) |
| 158 | *port = (phys_addr >> i) & 0xf; |
| 159 | for (i += 4; i < 16; i += 4) |
| 160 | if ((phys_addr & (0xf << i)) == 0) |
| 161 | return -EINVAL; |
| 162 | return 0; |
| 163 | } |
| 164 | EXPORT_SYMBOL_GPL(cec_phys_addr_validate); |
| 165 | |
| 166 | MODULE_AUTHOR("Hans Verkuil <hans.verkuil@cisco.com>"); |
| 167 | MODULE_DESCRIPTION("CEC EDID helper functions"); |
| 168 | MODULE_LICENSE("GPL"); |