nb/intel/gm45: Define and use MMCONF_BUS_NUMBER

Change-Id: I635f3615f566502f79bbd81f9f743ce63bba3b1a
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49758
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/northbridge/intel/gm45/Kconfig

@@ -29,6 +29,10 @@ config VGA_BIOS_ID
 config MMCONF_BASE_ADDRESS
 	default 0xf0000000
 
+config MMCONF_BUS_NUMBER
+	int
+	default 64
+
 config SMM_RESERVED_SIZE
 	hex
 	default 0x100000

src/northbridge/intel/gm45/acpi.c

@@ -13,15 +13,8 @@
 
 unsigned long acpi_fill_mcfg(unsigned long current)
 {
-	u32 length, pciexbar;
-
-	if (!decode_pcie_bar(&pciexbar, &length))
-		return current;
-
-	const int max_buses = length / MiB;
-
 	current += acpi_create_mcfg_mmconfig((acpi_mcfg_mmconfig_t *)current,
-			pciexbar, 0x0, 0x0, max_buses - 1);
+			CONFIG_MMCONF_BASE_ADDRESS, 0, 0, CONFIG_MMCONF_BUS_NUMBER - 1);
 
 	return current;
 }

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

@@ -18,7 +18,7 @@ Device (PDRC)
 		Memory32Fixed(ReadWrite, DEFAULT_MCHBAR,   0x00004000)
 		Memory32Fixed(ReadWrite, DEFAULT_DMIBAR,   0x00001000)
 		Memory32Fixed(ReadWrite, DEFAULT_EPBAR,    0x00001000)
-		Memory32Fixed(ReadWrite, CONFIG_MMCONF_BASE_ADDRESS, 0x04000000)
+		Memory32Fixed(ReadWrite, CONFIG_MMCONF_BASE_ADDRESS, CONFIG_MMCONF_LENGTH)
 		Memory32Fixed(ReadWrite, 0xfed20000, 0x00020000) // Misc ICH
 		Memory32Fixed(ReadWrite, 0xfed40000, 0x00005000) // Misc ICH
 		Memory32Fixed(ReadWrite, 0xfed45000, 0x0004b000) // Misc ICH

src/northbridge/intel/gm45/bootblock.c

@@ -1,14 +1,24 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
 #include <arch/bootblock.h>
+#include <assert.h>
 #include <device/pci_ops.h>
+#include <types.h>
 
 #include "gm45.h"
 
+static uint32_t encode_pciexbar_length(void)
+{
+	switch (CONFIG_MMCONF_BUS_NUMBER) {
+		case 256: return 0 << 1;
+		case 128: return 1 << 1;
+		case  64: return 2 << 1;
+		default:  return dead_code_t(uint32_t);
+	}
+}
+
 void bootblock_early_northbridge_init(void)
 {
-	uint32_t reg;
-
 	/*
 	 * The "io" variant of the config access is explicitly used to
 	 * setup the PCIEXBAR because CONFIG(MMCONF_SUPPORT) is set to
@@ -21,8 +31,7 @@ void bootblock_early_northbridge_init(void)
 	 * The PCIEXBAR is assumed to live in the memory mapped IO space under
 	 * 4GiB.
 	 */
-	reg = 0;
+	const uint32_t reg = CONFIG_MMCONF_BASE_ADDRESS | encode_pciexbar_length() | 1;
-	pci_io_write_config32(PCI_DEV(0,0,0), D0F0_PCIEXBAR_HI, reg);
+	pci_io_write_config32(PCI_DEV(0, 0, 0), D0F0_PCIEXBAR_HI, 0);
-	reg = CONFIG_MMCONF_BASE_ADDRESS | (2 << 1) | 1; /* 64MiB - 0-63 buses. */
 	pci_io_write_config32(PCI_DEV(0, 0, 0), D0F0_PCIEXBAR_LO, reg);
 }

src/northbridge/intel/gm45/gm45.h

@@ -444,8 +444,6 @@ struct blc_pwm_t {
 int get_blc_values(const struct blc_pwm_t **entries);
 u16 get_blc_pwm_freq_value(const char *edid_ascii_string);
 
-int decode_pcie_bar(u32 *const base, u32 *const len);
-
 #include <device/device.h>
 
 struct acpi_rsdp;

src/northbridge/intel/gm45/northbridge.c

@@ -14,43 +14,10 @@
 #include "chip.h"
 #include "gm45.h"
 
-int decode_pcie_bar(u32 *const base, u32 *const len)
-{
-	*base = 0;
-	*len = 0;
-
-	struct device *dev = pcidev_on_root(0, 0);
-	if (!dev)
-		return 0;
-
-	const u32 pciexbar_reg = pci_read_config32(dev, D0F0_PCIEXBAR_LO);
-
-	if (!(pciexbar_reg & (1 << 0)))
-		return 0;
-
-	switch ((pciexbar_reg >> 1) & 3) {
-	case 0: /* 256MB */
-		*base = pciexbar_reg & (0x0f << 28);
-		*len = 256 * MiB;
-		return 1;
-	case 1: /* 128M */
-		*base = pciexbar_reg & (0x1f << 27);
-		*len = 128 * MiB;
-		return 1;
-	case 2: /* 64M */
-		*base = pciexbar_reg & (0x3f << 26);
-		*len = 64 * MiB;
-		return 1;
-	}
-
-	return 0;
-}
-
 static void mch_domain_read_resources(struct device *dev)
 {
 	u64 tom, touud;
 	u32 tomk, tolud, uma_sizek = 0, delta_cbmem;
-	u32 pcie_config_base, pcie_config_size;
 
 	/* Total Memory 2GB example:
 	 *
@@ -157,12 +124,7 @@ static void mch_domain_read_resources(struct device *dev)
 	/* Don't use uma_resource() as our UMA touches the PCI hole. */
 	fixed_mem_resource(dev, 8, tomk, uma_sizek, IORESOURCE_RESERVE);
 
-	if (decode_pcie_bar(&pcie_config_base, &pcie_config_size)) {
+	mmconf_resource(dev, 9);
-		printk(BIOS_DEBUG, "Adding PCIe config bar base=0x%08x "
-		       "size=0x%x\n", pcie_config_base, pcie_config_size);
-		fixed_mem_resource(dev, 9, pcie_config_base >> 10,
-			pcie_config_size >> 10, IORESOURCE_RESERVE);
-	}
 }
 
 static void mch_domain_set_resources(struct device *dev)