nb/intel/gm45: Allow for PCI BARs above 4G

Linux needs to know that allocating BARs above 4G is fine so reserve a
region in ACPI for that.

Tested on thinkpad X200: a PCIe window gets allocated above 4G and
Linux does not relocate it.

Change-Id: I62a8a656481eba01add3d7d06b42e3352206df1b
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64094
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/northbridge/intel/gm45/acpi/hostbridge.asl

@@ -188,6 +188,12 @@ Name (MCRS, ResourceTemplate()
 			0x00000000, 0x00000000, 0xfebfffff, 0x00000000,
 			IO_APIC_ADDR,,, PM01)
 
+	/* PCI Memory Region above 4G TOUUD -> 1 << cpu_addr_bits */
+	QWordMemory (ResourceProducer, PosDecode, MinFixed, MaxFixed,
+			Cacheable, ReadWrite,
+			0x00000000, 0x00000000, 0x00000000, 0x00000000,
+			0x00000000,,, PM02)
+
 	/* TPM Area (0xfed40000-0xfed44fff) */
 	DWordMemory (ResourceProducer, PosDecode, MinFixed, MaxFixed,
 			Cacheable, ReadWrite,
@@ -195,6 +201,9 @@ Name (MCRS, ResourceTemplate()
 			0x00005000,,, TPMR)
 })
 
+External (A4GS, IntObj)
+External (A4GB, IntObj)
+
 /* Current Resource Settings */
 Method (_CRS, 0, Serialized)
 {
@@ -211,5 +220,15 @@ Method (_CRS, 0, Serialized)
 	PMIN = ^MCHC.TLUD << 20
 	PLEN = PMAX - PMIN + 1
 
+	if (A4GS != 0) {
+		CreateQwordField(MCRS, ^PM02._MIN, MMIN)
+		CreateQwordField(MCRS, ^PM02._MAX, MMAX)
+		CreateQwordField(MCRS, ^PM02._LEN, MLEN)
+		/* Set 64bit MMIO resource base and length */
+		MLEN = A4GS
+		MMIN = A4GB
+		MMAX = MMIN + MLEN - 1
+	}
+
 	Return (MCRS)
 }

src/northbridge/intel/gm45/northbridge.c

@@ -1,19 +1,28 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <acpi/acpi.h>
+#include <acpi/acpigen.h>
+#include <boot/tables.h>
 #include <cbmem.h>
 #include <commonlib/helpers.h>
 #include <console/console.h>
+#include <cpu/cpu.h>
+#include <cpu/intel/smm_reloc.h>
+#include <device/device.h>
 #include <device/pci_def.h>
 #include <device/pci_ops.h>
 #include <stdint.h>
-#include <device/device.h>
-#include <boot/tables.h>
-#include <acpi/acpi.h>
-#include <cpu/intel/smm_reloc.h>
 
 #include "chip.h"
 #include "gm45.h"
 
+static uint64_t get_touud(void)
+{
+	uint64_t touud = pci_read_config16(__pci_0_00_0, D0F0_TOUUD);
+	touud <<= 20;
+	return touud;
+}
+
 static void mch_domain_read_resources(struct device *dev)
 {
 	u64 tom, touud;
@@ -43,8 +52,7 @@ static void mch_domain_read_resources(struct device *dev)
 	struct device *mch = pcidev_on_root(0, 0);
 
 	/* Top of Upper Usable DRAM, including remap */
-	touud = pci_read_config16(mch, D0F0_TOUUD);
+	touud = get_touud();
-	touud <<= 20;
 
 	/* Top of Lower Usable DRAM */
 	tolud = pci_read_config16(mch, D0F0_TOLUD) & 0xfff0;
@@ -176,13 +184,33 @@ void northbridge_write_smram(u8 smram)
 	pci_write_config8(dev, D0F0_SMRAM, smram);
 }
 
+static void set_above_4g_pci(const struct device *dev)
+{
+	const uint64_t touud = get_touud();
+	const uint64_t len = POWER_OF_2(cpu_phys_address_size()) - touud;
+
+	const char *scope = acpi_device_path(dev);
+	acpigen_write_scope(scope);
+	acpigen_write_name_qword("A4GB", touud);
+	acpigen_write_name_qword("A4GS", len);
+	acpigen_pop_len();
+
+	printk(BIOS_DEBUG, "PCI space above 4GB MMIO is at 0x%llx, len = 0x%llx\n", touud, len);
+}
+
+static void pci_domain_ssdt(const struct device *dev)
+{
+	generate_cpu_entries(dev);
+	set_above_4g_pci(dev);
+}
+
 static struct device_operations pci_domain_ops = {
 	.read_resources   = mch_domain_read_resources,
 	.set_resources    = mch_domain_set_resources,
 	.init             = mch_domain_init,
 	.scan_bus         = pci_domain_scan_bus,
 	.write_acpi_tables = northbridge_write_acpi_tables,
-	.acpi_fill_ssdt   = generate_cpu_entries,
+	.acpi_fill_ssdt   = pci_domain_ssdt,
 	.acpi_name        = northbridge_acpi_name,
 };