drm/i915/dg1: Read OPROM via SPI controller

Read OPROM SPI through MMIO and find VBT entry since we can't use
OpRegion and PCI mapping may not work on some systems due to most BIOSes
not leaving the Option ROM mapped.

v2: Remove message with allocation failure

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Clint Taylor <clinton.a.taylor@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211216062645.3477854-1-lucas.demarchi@intel.com
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 8528db2..5b502c8f 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -12853,6 +12853,14 @@ enum skl_power_gate {
 #define  TCSS_DDI_STATUS_HPD_LIVE_STATUS_TBT	REG_BIT(1)
 #define  TCSS_DDI_STATUS_HPD_LIVE_STATUS_ALT	REG_BIT(0)
 
+#define PRIMARY_SPI_TRIGGER			_MMIO(0x102040)
+#define PRIMARY_SPI_ADDRESS			_MMIO(0x102080)
+#define PRIMARY_SPI_REGIONID			_MMIO(0x102084)
+#define SPI_STATIC_REGIONS			_MMIO(0x102090)
+#define   OPTIONROM_SPI_REGIONID_MASK		REG_GENMASK(7, 0)
+#define OROM_OFFSET				_MMIO(0x1020c0)
+#define   OROM_OFFSET_MASK			REG_GENMASK(20, 16)
+
 /* This register controls the Display State Buffer (DSB) engines. */
 #define _DSBSL_INSTANCE_BASE		0x70B00
 #define DSBSL_INSTANCE(pipe, id)	(_DSBSL_INSTANCE_BASE + \