drivers/intel/gma: Restructure IGD opregion init code

Restructuring opregion VBT related code to make it more generalize
for future revision of opregion spec.

Moved logic to locate VBT from different region (CBMEM, PCI option
ROM or VBIOS) into separate function.

Created a new function to check if extended VBT region is required.
This will be helpful in the subsequent changes to determine if
extended VBT region is needed and handle memory allocation
accordingly.

BUG=None
BRANCH=None
TEST=check the address of extended VBT region and address is coming
correctly.

Change-Id: I479d57cd326567192a3cd1969f8125ffe1934399
Signed-off-by: MAULIK V VAGHELA <maulik.v.vaghela@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55318
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>

1 files changed, 43 insertions, 24 deletions

diff --git a/src/drivers/intel/gma/opregion.c b/src/drivers/intel/gma/opregion.c
index cf2c5d9846..b25a2f6ce8 100644
--- a/src/drivers/intel/gma/opregion.c
+++ b/src/drivers/intel/gma/opregion.c
@@ -218,29 +218,26 @@ static enum cb_err locate_vbt_vbios_cbfs(struct region_device *rdev)
 	return locate_vbt_vbios(oprom, rdev);
 }
 
-/* Initialize IGD OpRegion, called from ACPI code and OS drivers */
-enum cb_err intel_gma_init_igd_opregion(void)
+/*
+ * Try to locate VBT in possible locations and return if found.
+ * VBT can be possibly in one of 3 regions:
+ *  1. Stitched directly into CBFS region as VBT
+ *  2. Part of pci8086 option ROM within CBFS
+ *  3. part of VBIOS at location 0xC0000.
+ */
+static enum cb_err find_vbt_location(struct region_device *rdev)
 {
-	igd_opregion_t *opregion;
-	struct region_device rdev;
-	optionrom_vbt_t *vbt = NULL;
-	optionrom_vbt_t *ext_vbt;
-	bool found = false;
-
-	if (acpi_is_wakeup_s3())
-		return intel_gma_restore_opregion();
-
 	/* Search for vbt.bin in CBFS. */
-	if (locate_vbt_cbfs(&rdev) == CB_SUCCESS &&
-	    vbt_validate(&rdev) == CB_SUCCESS) {
-		found = true;
+	if (locate_vbt_cbfs(rdev) == CB_SUCCESS &&
+	    vbt_validate(rdev) == CB_SUCCESS) {
 		printk(BIOS_INFO, "GMA: Found valid VBT in CBFS\n");
+		return CB_SUCCESS;
 	}
 	/* Search for pci8086,XXXX.rom in CBFS. */
-	else if (locate_vbt_vbios_cbfs(&rdev) == CB_SUCCESS &&
-		 vbt_validate(&rdev) == CB_SUCCESS) {
-		found = true;
+	else if (locate_vbt_vbios_cbfs(rdev) == CB_SUCCESS &&
+		 vbt_validate(rdev) == CB_SUCCESS) {
 		printk(BIOS_INFO, "GMA: Found valid VBT in VBIOS\n");
+		return CB_SUCCESS;
 	}
 	/*
 	 * Try to locate Intel VBIOS at 0xc0000. It might have been placed by
@@ -248,16 +245,38 @@ enum cb_err intel_gma_init_igd_opregion(void)
 	 * VBIOS on legacy platforms.
 	 * TODO: Place generated fake VBT in CBMEM and get rid of this.
 	 */
-	else if (locate_vbt_vbios((u8 *)0xc0000, &rdev) == CB_SUCCESS &&
-		 vbt_validate(&rdev) == CB_SUCCESS) {
-		found = true;
+	else if (locate_vbt_vbios((u8 *)0xc0000, rdev) == CB_SUCCESS &&
+		 vbt_validate(rdev) == CB_SUCCESS) {
 		printk(BIOS_INFO, "GMA: Found valid VBT in legacy area\n");
+		return CB_SUCCESS;
 	}
 
-	if (!found) {
-		printk(BIOS_ERR, "GMA: VBT couldn't be found\n");
+	return CB_ERR;
+}
+
+/*
+ * Function to determine if we need to use extended VBT region to pass
+ * VBT pointer. If VBT size > 6 KiB then we need to use extended VBT
+ * region.
+ */
+static inline bool is_ext_vbt_required(igd_opregion_t *opregion, optionrom_vbt_t *vbt)
+{
+	return (vbt->hdr_vbt_size > sizeof(opregion->vbt.gvd1));
+}
+
+/* Initialize IGD OpRegion, called from ACPI code and OS drivers */
+enum cb_err intel_gma_init_igd_opregion(void)
+{
+	igd_opregion_t *opregion;
+	struct region_device rdev;
+	optionrom_vbt_t *vbt = NULL;
+	optionrom_vbt_t *ext_vbt = NULL;
+
+	if (acpi_is_wakeup_s3())
+		return intel_gma_restore_opregion();
+
+	if (find_vbt_location(&rdev) != CB_SUCCESS)
 		return CB_ERR;
-	}
 
 	vbt = rdev_mmap_full(&rdev);
 	if (!vbt) {
@@ -284,7 +303,7 @@ enum cb_err intel_gma_init_igd_opregion(void)
 	memcpy(opregion->header.vbios_version, vbt->coreblock_biosbuild,
 					ARRAY_SIZE(vbt->coreblock_biosbuild));
 	/* Extended VBT support */
-	if (vbt->hdr_vbt_size > sizeof(opregion->vbt.gvd1)) {
+	if (is_ext_vbt_required(opregion, vbt)) {
 		ext_vbt = cbmem_add(CBMEM_ID_EXT_VBT, vbt->hdr_vbt_size);
 
 		if (ext_vbt == NULL) {