diff options
Diffstat (limited to 'drivers/media/cec-edid.c')
| -rw-r--r-- | drivers/media/cec-edid.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/drivers/media/cec-edid.c b/drivers/media/cec-edid.c new file mode 100644 index 000000000..5719b991e --- /dev/null +++ b/drivers/media/cec-edid.c @@ -0,0 +1,171 @@ +/* + * cec-edid - HDMI Consumer Electronics Control EDID & CEC helper functions + * + * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights reserved. + * + * This program is free software; you may redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/types.h> +#include <media/cec-edid.h> + +/* + * This EDID is expected to be a CEA-861 compliant, which means that there are + * at least two blocks and one or more of the extensions blocks are CEA-861 + * blocks. + * + * The returned location is guaranteed to be < size - 1. + */ +static unsigned int cec_get_edid_spa_location(const u8 *edid, unsigned int size) +{ + unsigned int blocks = size / 128; + unsigned int block; + u8 d; + + /* Sanity check: at least 2 blocks and a multiple of the block size */ + if (blocks < 2 || size % 128) + return 0; + + /* + * If there are fewer extension blocks than the size, then update + * 'blocks'. It is allowed to have more extension blocks than the size, + * since some hardware can only read e.g. 256 bytes of the EDID, even + * though more blocks are present. The first CEA-861 extension block + * should normally be in block 1 anyway. + */ + if (edid[0x7e] + 1 < blocks) + blocks = edid[0x7e] + 1; + + for (block = 1; block < blocks; block++) { + unsigned int offset = block * 128; + + /* Skip any non-CEA-861 extension blocks */ + if (edid[offset] != 0x02 || edid[offset + 1] != 0x03) + continue; + + /* search Vendor Specific Data Block (tag 3) */ + d = edid[offset + 2] & 0x7f; + /* Check if there are Data Blocks */ + if (d <= 4) + continue; + if (d > 4) { + unsigned int i = offset + 4; + unsigned int end = offset + d; + + /* Note: 'end' is always < 'size' */ + do { + u8 tag = edid[i] >> 5; + u8 len = edid[i] & 0x1f; + + if (tag == 3 && len >= 5 && i + len <= end && + edid[i + 1] == 0x03 && + edid[i + 2] == 0x0c && + edid[i + 3] == 0x00) + return i + 4; + i += len + 1; + } while (i < end); + } + } + return 0; +} + +u16 cec_get_edid_phys_addr(const u8 *edid, unsigned int size, + unsigned int *offset) +{ + unsigned int loc = cec_get_edid_spa_location(edid, size); + + if (offset) + *offset = loc; + if (loc == 0) + return CEC_PHYS_ADDR_INVALID; + return (edid[loc] << 8) | edid[loc + 1]; +} +EXPORT_SYMBOL_GPL(cec_get_edid_phys_addr); + +void cec_set_edid_phys_addr(u8 *edid, unsigned int size, u16 phys_addr) +{ + unsigned int loc = cec_get_edid_spa_location(edid, size); + u8 sum = 0; + unsigned int i; + + if (loc == 0) + return; + edid[loc] = phys_addr >> 8; + edid[loc + 1] = phys_addr & 0xff; + loc &= ~0x7f; + + /* update the checksum */ + for (i = loc; i < loc + 127; i++) + sum += edid[i]; + edid[i] = 256 - sum; +} +EXPORT_SYMBOL_GPL(cec_set_edid_phys_addr); + +u16 cec_phys_addr_for_input(u16 phys_addr, u8 input) +{ + /* Check if input is sane */ + if (WARN_ON(input == 0 || input > 0xf)) + return CEC_PHYS_ADDR_INVALID; + + if (phys_addr == 0) + return input << 12; + + if ((phys_addr & 0x0fff) == 0) + return phys_addr | (input << 8); + + if ((phys_addr & 0x00ff) == 0) + return phys_addr | (input << 4); + + if ((phys_addr & 0x000f) == 0) + return phys_addr | input; + + /* + * All nibbles are used so no valid physical addresses can be assigned + * to the input. + */ + return CEC_PHYS_ADDR_INVALID; +} +EXPORT_SYMBOL_GPL(cec_phys_addr_for_input); + +int cec_phys_addr_validate(u16 phys_addr, u16 *parent, u16 *port) +{ + int i; + + if (parent) + *parent = phys_addr; + if (port) + *port = 0; + if (phys_addr == CEC_PHYS_ADDR_INVALID) + return 0; + for (i = 0; i < 16; i += 4) + if (phys_addr & (0xf << i)) + break; + if (i == 16) + return 0; + if (parent) + *parent = phys_addr & (0xfff0 << i); + if (port) + *port = (phys_addr >> i) & 0xf; + for (i += 4; i < 16; i += 4) + if ((phys_addr & (0xf << i)) == 0) + return -EINVAL; + return 0; +} +EXPORT_SYMBOL_GPL(cec_phys_addr_validate); + +MODULE_AUTHOR("Hans Verkuil <hans.verkuil@cisco.com>"); +MODULE_DESCRIPTION("CEC EDID helper functions"); +MODULE_LICENSE("GPL"); |