drm/i915/bios: Define VBT block 5 (Generic Mode Table)

Define the contents of VBT block 5 (Generic Mode Table).

Details were mostly gleaned from some VBIOS sources.

There are apparently two variants of the block: ALM only
vs. MGM, defined here as bdb_generic_mode_table_alm
and bdb_generic_mode_table_mgm. And those are the only two
platforms where I've seen this block.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240503122449.27266-12-ville.syrjala@linux.intel.comAcked-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_vbt_defs.h

@@ -580,6 +580,60 @@ struct bdb_mode_support_list {
 	u16 mode_list_length;
 } __packed;
 
+/*
+ * Block 5 - Generic Mode Table
+ */
+
+struct generic_mode_table {
+	u16 x_res;
+	u16 y_res;
+	u8 color_depths;
+	u8 refresh_rate[3];
+	u8 reserved;
+	u8 text_cols;
+	u8 text_rows;
+	u8 font_height;
+	u16 page_size;
+	u8 misc;
+} __packed;
+
+struct generic_mode_timings {
+	u32 dotclock_khz;
+	u16 hdisplay;
+	u16 htotal;
+	u16 hblank_start;
+	u16 hblank_end;
+	u16 hsync_start;
+	u16 hsync_end;
+	u16 vdisplay;
+	u16 vtotal;
+	u16 vblank_start;
+	u16 vblank_end;
+	u16 vsync_start;
+	u16 vsync_end;
+} __packed;
+
+struct generic_mode_timings_alm {
+	struct generic_mode_timings timings;
+	u8 wm_8bpp;
+	u8 burst_8bpp;
+	u8 wm_16bpp;
+	u8 burst_16bpp;
+	u8 wm_32bpp;
+	u8 burst_32bpp;
+} __packed;
+
+struct bdb_generic_mode_table_alm {
+	struct generic_mode_table table;
+	struct generic_mode_timings_alm timings[3];
+} __packed;
+
+struct bdb_generic_mode_table_mgm {
+	u16 mode_flag;
+	struct generic_mode_table table;
+	struct generic_mode_timings timings[3];
+} __packed;
+
 /*
  * Block 9 - SRD Feature Block
  */