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// SPDX-License-Identifier: MIT
/*
* Copyright © 2021 Intel Corporation
*/
#include <drm/drm_edid.h>
#include <drm/drm_print.h>
#include "drm_crtc_internal.h"
#include "drm_displayid_internal.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;
/* +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 struct displayid_header *base;
const u8 *displayid;
displayid = drm_edid_find_extension(drm_edid, DISPLAYID_EXT, ext_index);
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;
}
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