drm/i915/bios: add proper documentation for the Video BIOS Table (VBT)

Add an overview and documentation for the VBT/BDB header structures.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/3d826d4600688ca3518713776ab5bd8a8fc9f20f.1450702954.git.jani.nikula@intel.com
This commit is contained in:
Jani Nikula
2015-12-21 15:10:52 +02:00
parent 0bff485865
commit dd97950a4c
3 changed files with 57 additions and 11 deletions

View File

@@ -28,22 +28,40 @@
#ifndef _I830_BIOS_H_
#define _I830_BIOS_H_
/**
* struct vbt_header - VBT Header structure
* @signature: VBT signature, always starts with "$VBT"
* @version: Version of this structure
* @header_size: Size of this structure
* @vbt_size: Size of VBT (VBT Header, BDB Header and data blocks)
* @vbt_checksum: Checksum
* @reserved0: Reserved
* @bdb_offset: Offset of &struct bdb_header from beginning of VBT
* @aim_offset: Offsets of add-in data blocks from beginning of VBT
*/
struct vbt_header {
u8 signature[20]; /**< Always starts with 'VBT$' */
u16 version; /**< decimal */
u16 header_size; /**< in bytes */
u16 vbt_size; /**< in bytes */
u8 signature[20];
u16 version;
u16 header_size;
u16 vbt_size;
u8 vbt_checksum;
u8 reserved0;
u32 bdb_offset; /**< from beginning of VBT */
u32 aim_offset[4]; /**< from beginning of VBT */
u32 bdb_offset;
u32 aim_offset[4];
} __packed;
/**
* struct bdb_header - BDB Header structure
* @signature: BDB signature "BIOS_DATA_BLOCK"
* @version: Version of the data block definitions
* @header_size: Size of this structure
* @bdb_size: Size of BDB (BDB Header and data blocks)
*/
struct bdb_header {
u8 signature[16]; /**< Always 'BIOS_DATA_BLOCK' */
u16 version; /**< decimal */
u16 header_size; /**< in bytes */
u16 bdb_size; /**< in bytes */
u8 signature[16];
u16 version;
u16 header_size;
u16 bdb_size;
} __packed;
/* strictly speaking, this is a "skip" block, but it has interesting info */