diff options
Diffstat (limited to 'drivers/gpu/drm/drm_displayid.c')
| -rw-r--r-- | drivers/gpu/drm/drm_displayid.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_displayid.c b/drivers/gpu/drm/drm_displayid.c new file mode 100644 index 000000000..9edc111be --- /dev/null +++ b/drivers/gpu/drm/drm_displayid.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: MIT +/* + * Copyright © 2021 Intel Corporation + */ + +#include <drm/drm_displayid.h> +#include <drm/drm_edid.h> +#include <drm/drm_print.h> + +static const struct displayid_header * +displayid_get_header(const u8 *displayid, int length, int index) +{ + const struct displayid_header *base; + + if (sizeof(*base) > length - index) + return ERR_PTR(-EINVAL); + + base = (const struct displayid_header *)&displayid[index]; + + return base; +} + +static const struct displayid_header * +validate_displayid(const u8 *displayid, int length, int idx) +{ + int i, dispid_length; + u8 csum = 0; + const struct displayid_header *base; + + base = displayid_get_header(displayid, length, idx); + if (IS_ERR(base)) + return base; + + DRM_DEBUG_KMS("base revision 0x%x, length %d, %d %d\n", + base->rev, base->bytes, base->prod_id, base->ext_count); + + /* +1 for DispID checksum */ + dispid_length = sizeof(*base) + base->bytes + 1; + if (dispid_length > length - idx) + return ERR_PTR(-EINVAL); + + for (i = 0; i < dispid_length; i++) + csum += displayid[idx + i]; + if (csum) { + DRM_NOTE("DisplayID checksum invalid, remainder is %d\n", csum); + return ERR_PTR(-EINVAL); + } + + return base; +} + +static const u8 *drm_find_displayid_extension(const struct drm_edid *drm_edid, + int *length, int *idx, + int *ext_index) +{ + const u8 *displayid = drm_find_edid_extension(drm_edid, DISPLAYID_EXT, ext_index); + const struct displayid_header *base; + + if (!displayid) + return NULL; + + /* EDID extensions block checksum isn't for us */ + *length = EDID_LENGTH - 1; + *idx = 1; + + base = validate_displayid(displayid, *length, *idx); + if (IS_ERR(base)) + return NULL; + + *length = *idx + sizeof(*base) + base->bytes; + + return displayid; +} + +void displayid_iter_edid_begin(const struct drm_edid *drm_edid, + struct displayid_iter *iter) +{ + memset(iter, 0, sizeof(*iter)); + + iter->drm_edid = drm_edid; +} + +static const struct displayid_block * +displayid_iter_block(const struct displayid_iter *iter) +{ + const struct displayid_block *block; + + if (!iter->section) + return NULL; + + block = (const struct displayid_block *)&iter->section[iter->idx]; + + if (iter->idx + sizeof(*block) <= iter->length && + iter->idx + sizeof(*block) + block->num_bytes <= iter->length) + return block; + + return NULL; +} + +const struct displayid_block * +__displayid_iter_next(struct displayid_iter *iter) +{ + const struct displayid_block *block; + + if (!iter->drm_edid) + return NULL; + + if (iter->section) { + /* current block should always be valid */ + block = displayid_iter_block(iter); + if (WARN_ON(!block)) { + iter->section = NULL; + iter->drm_edid = NULL; + return NULL; + } + + /* next block in section */ + iter->idx += sizeof(*block) + block->num_bytes; + + block = displayid_iter_block(iter); + if (block) + return block; + } + + for (;;) { + /* The first section we encounter is the base section */ + bool base_section = !iter->section; + + iter->section = drm_find_displayid_extension(iter->drm_edid, + &iter->length, + &iter->idx, + &iter->ext_index); + if (!iter->section) { + iter->drm_edid = NULL; + return NULL; + } + + /* Save the structure version and primary use case. */ + if (base_section) { + const struct displayid_header *base; + + base = displayid_get_header(iter->section, iter->length, + iter->idx); + if (!IS_ERR(base)) { + iter->version = base->rev; + iter->primary_use = base->prod_id; + } + } + + iter->idx += sizeof(struct displayid_header); + + block = displayid_iter_block(iter); + if (block) + return block; + } +} + +void displayid_iter_end(struct displayid_iter *iter) +{ + memset(iter, 0, sizeof(*iter)); +} + +/* DisplayID Structure Version/Revision from the Base Section. */ +u8 displayid_version(const struct displayid_iter *iter) +{ + return iter->version; +} + +/* + * DisplayID Primary Use Case (2.0+) or Product Type Identifier (1.0-1.3) from + * the Base Section. + */ +u8 displayid_primary_use(const struct displayid_iter *iter) +{ + return iter->primary_use; +} |