path: root/resources/coreboot/haswell/patches/0003-haswell-lynxpoint-Add-native-DMI-init.patch

From 6ec71c6df97eded010e96c4ea2bd37cc6a13849d Mon Sep 17 00:00:00 2001
From: Angel Pons <th3fanbus@gmail.com>
Date: Fri, 6 May 2022 21:56:48 +0200
Subject: [PATCH 03/26] haswell/lynxpoint: Add native DMI init

Implement native DMI init for Haswell and Lynx Point. This is only
needed on non-ULT platforms, and only when MRC.bin is not used.

TEST=Verify DMI initialises correctly on Asrock B85M Pro4.

Change-Id: I5fb1a2adc4ffbf0ebbf0d2d3a444055c53765faa
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
---
 src/northbridge/intel/haswell/Makefile.inc    |   1 +
 src/northbridge/intel/haswell/early_dmi.c     |  96 ++++++++++++
 src/northbridge/intel/haswell/early_pcie.c    | 121 ++++++++++++++
 src/northbridge/intel/haswell/haswell.h       |   3 +
 .../haswell/native_raminit/raminit_native.c   |  15 ++
 src/northbridge/intel/haswell/vcu_mailbox.c   | 147 ++++++++++++++++++
 src/northbridge/intel/haswell/vcu_mailbox.h   |  16 ++
 src/southbridge/intel/lynxpoint/Makefile.inc  |   2 +
 .../intel/lynxpoint/early_pch_native.c        |  52 +++++++
 src/southbridge/intel/lynxpoint/pch.h         |  20 ++-
 10 files changed, 472 insertions(+), 1 deletion(-)
 create mode 100644 src/northbridge/intel/haswell/early_dmi.c
 create mode 100644 src/northbridge/intel/haswell/early_pcie.c
 create mode 100644 src/northbridge/intel/haswell/vcu_mailbox.c
 create mode 100644 src/northbridge/intel/haswell/vcu_mailbox.h
 create mode 100644 src/southbridge/intel/lynxpoint/early_pch_native.c

diff --git a/src/northbridge/intel/haswell/Makefile.inc b/src/northbridge/intel/haswell/Makefile.inc
index 329f1f7ffe..df0b097296 100644
--- a/src/northbridge/intel/haswell/Makefile.inc
+++ b/src/northbridge/intel/haswell/Makefile.inc
@@ -20,6 +20,7 @@ romstage-y += report_platform.c
 postcar-y += memmap.c
 
 ifeq ($(CONFIG_USE_NATIVE_RAMINIT),y)
+romstage-y += early_dmi.c early_pcie.c vcu_mailbox.c
 subdirs-y  += native_raminit
 
 else
diff --git a/src/northbridge/intel/haswell/early_dmi.c b/src/northbridge/intel/haswell/early_dmi.c
new file mode 100644
index 0000000000..9941242fd5
--- /dev/null
+++ b/src/northbridge/intel/haswell/early_dmi.c
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <console/console.h>
+#include <northbridge/intel/haswell/haswell.h>
+#include <southbridge/intel/lynxpoint/pch.h>
+#include <types.h>
+
+static void dmi_print_link_status(int loglevel)
+{
+	const uint16_t dmilsts = dmibar_read16(DMILSTS);
+	printk(loglevel, "DMI: Running at Gen%u x%u\n", dmilsts & 0xf, dmilsts >> 4 & 0x1f);
+}
+
+#define RETRAIN	(1 << 5)
+
+#define LTRN	(1 << 11)
+
+static void dmi_setup_physical_layer(void)
+{
+	/* Program DMI AFE settings, which are needed for DMI to work */
+	peg_dmi_recipe(false, 0);
+
+	/* Additional DMI programming steps */
+	dmibar_setbits32(0x258, 1 << 29);
+	dmibar_clrsetbits32(0x208, 0x7ff, 0x6b5);
+	dmibar_clrsetbits32(0x22c, 0xffff, 0x2020);
+
+	/* Write SA reference code version */
+	dmibar_write32(0x71c, 0x0000000f);
+	dmibar_write32(0x720, 0x01060200);
+
+	/* We also have to bring up the PCH side of the DMI link */
+	pch_dmi_setup_physical_layer();
+
+	/* Write-once settings */
+	dmibar_clrsetbits32(DMILCAP, 0x3f00f, 2 << 0);
+
+	printk(BIOS_DEBUG, "Retraining DMI at Gen2 speeds...\n");
+	dmi_print_link_status(BIOS_DEBUG);
+
+	/* Retrain link */
+	dmibar_setbits16(DMILCTL, RETRAIN);
+	do {} while (dmibar_read16(DMILSTS) & LTRN);
+	dmi_print_link_status(BIOS_DEBUG);
+
+	/* Retrain link again for DMI Gen2 speeds */
+	dmibar_setbits16(DMILCTL, RETRAIN);
+	do {} while (dmibar_read16(DMILSTS) & LTRN);
+	dmi_print_link_status(BIOS_INFO);
+}
+
+#define VC_ACTIVE	(1U << 31)
+
+#define VCNEGPND	(1 << 1)
+
+#define DMI_VC_CFG(vcid, tcmap)	(VC_ACTIVE | ((vcid) << 24) | (tcmap))
+
+static void dmi_tc_vc_mapping(void)
+{
+	printk(BIOS_DEBUG, "Programming SA  DMI VC/TC mappings...\n");
+
+	if (CONFIG(INTEL_LYNXPOINT_LP))
+		dmibar_setbits8(0xa78, 1 << 1);
+
+	/* Each TC is mapped to one and only one VC */
+	const u32 vc0 = DMI_VC_CFG(0, (1 << 6) | (1 << 5) | (1 << 4) | (1 << 3) | (1 << 0));
+	const u32 vc1 = DMI_VC_CFG(1, (1 << 1));
+	const u32 vcp = DMI_VC_CFG(2, (1 << 2));
+	const u32 vcm = DMI_VC_CFG(7, (1 << 7));
+	dmibar_write32(DMIVC0RCTL, vc0);
+	dmibar_write32(DMIVC1RCTL, vc1);
+	dmibar_write32(DMIVCPRCTL, vcp);
+	dmibar_write32(DMIVCMRCTL, vcm);
+
+	/* Set Extended VC Count (EVCC) to 1 if VC1 is active */
+	dmibar_clrsetbits8(DMIPVCCAP1, 7, !!(vc1 & VC_ACTIVE));
+
+	/*
+	 * We also have to program the PCH side of the DMI link. Since both ends
+	 * must use the same Virtual Channel settings, we pass them as arguments.
+	 */
+	pch_dmi_tc_vc_mapping(vc0, vc1, vcp, vcm);
+
+	printk(BIOS_DEBUG, "Waiting for SA  DMI VC negotiation... ");
+	do {} while (dmibar_read16(DMIVC0RSTS) & VCNEGPND);
+	do {} while (dmibar_read16(DMIVC1RSTS) & VCNEGPND);
+	do {} while (dmibar_read16(DMIVCPRSTS) & VCNEGPND);
+	do {} while (dmibar_read16(DMIVCMRSTS) & VCNEGPND);
+	printk(BIOS_DEBUG, "done!\n");
+}
+
+void dmi_early_init(void)
+{
+	dmi_setup_physical_layer();
+	dmi_tc_vc_mapping();
+}
diff --git a/src/northbridge/intel/haswell/early_pcie.c b/src/northbridge/intel/haswell/early_pcie.c
new file mode 100644
index 0000000000..d3940e3fac
--- /dev/null
+++ b/src/northbridge/intel/haswell/early_pcie.c
@@ -0,0 +1,121 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <console/console.h>
+#include <device/pci_def.h>
+#include <device/pci_mmio_cfg.h>
+#include <device/pci_ops.h>
+#include <northbridge/intel/haswell/haswell.h>
+#include <northbridge/intel/haswell/vcu_mailbox.h>
+#include <types.h>
+
+#define PEG_DEV(func)		PCI_DEV(0, 1, func)
+
+#define MAX_PEG_FUNC		3
+
+static void peg_dmi_unset_and_set_mask_pcicfg(
+	volatile union pci_bank *const bank,
+	const uint32_t offset,
+	const uint32_t unset_mask,
+	const uint32_t set_mask,
+	const uint32_t shift,
+	const bool valid)
+{
+	if (!valid)
+		return;
+
+	volatile uint32_t *const addr = &bank->reg32[offset / sizeof(uint32_t)];
+	clrsetbits32(addr, unset_mask << shift, set_mask << shift);
+}
+
+static void peg_dmi_unset_and_set_mask_common(
+	const bool is_peg,
+	const uint32_t offset,
+	const uint32_t unset,
+	const uint32_t set,
+	const uint32_t shift,
+	const bool valid)
+{
+	const uint32_t unset_mask = unset << shift;
+	const uint32_t   set_mask =   set << shift;
+	if (is_peg) {
+		for (uint8_t i = 0; i < MAX_PEG_FUNC; i++)
+			pci_update_config32(PEG_DEV(i), offset, ~unset_mask, set_mask);
+	} else {
+		dmibar_clrsetbits32(offset, unset_mask, set_mask);
+	}
+}
+
+static void peg_dmi_unset_and_set_mask_vcu_mmio(
+	const uint32_t addr,
+	const uint32_t unset_mask,
+	const uint32_t set_mask,
+	const uint32_t shift,
+	const bool valid)
+{
+	if (!valid)
+		return;
+
+	vcu_update_mmio(addr, ~(unset_mask << shift), set_mask << shift);
+}
+
+#define BUNDLE_STEP	0x20
+
+static void *const dmibar = (void *)(uintptr_t)CONFIG_FIXED_DMIBAR_MMIO_BASE;
+
+void peg_dmi_recipe(const bool is_peg, const pci_devfn_t dev)
+{
+	const bool always = true;
+	const bool is_dmi = !is_peg;
+
+	/* Treat DMIBAR and PEG devices the same way */
+	volatile union pci_bank *const bank = is_peg ? pci_map_bus(dev) : dmibar;
+
+	const size_t bundles = (is_peg ? 8 : 2) * BUNDLE_STEP;
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP) {
+		/* These are actually per-lane */
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0xa00 + i, 0x1f, 0x0c,  0, always);
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0xa10 + i, 0x1f, 0x0c,  0, always);
+	}
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x904 + i, 0x1f, 0x02,  0, is_peg);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x904 + i, 0x1f, 0x03,  5, is_peg);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x90c + i, 0x3f, 0x09,  5, always);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x90c + i, 0x0f, 0x05, 21, is_peg);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x910 + i, 0x0f, 0x08,  6, is_peg);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x910 + i, 0x0f, 0x00, 10, always);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x910 + i, 0x07, 0x00, 18, always);
+
+	peg_dmi_unset_and_set_mask_vcu_mmio(0x0c008001, 0x1f, 0x03, 25, is_peg);
+	peg_dmi_unset_and_set_mask_vcu_mmio(0x0c0c8001, 0x3f, 0x00, 23, is_dmi);
+
+	peg_dmi_unset_and_set_mask_pcicfg(bank, 0xc28, 0x1f, 0x13, 18, always);
+
+	peg_dmi_unset_and_set_mask_common(is_peg, 0xc38, 0x01, 0x00,  6, always);
+	peg_dmi_unset_and_set_mask_common(is_peg, 0x260, 0x03, 0x02,  0, always);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x900 + i, 0x03, 0x00, 26, always);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x904 + i, 0x03, 0x03, 10, always);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x90c + i, 0x1f, 0x07, 25, is_peg);
+
+	for (size_t i = 0; i < bundles; i += BUNDLE_STEP)
+		peg_dmi_unset_and_set_mask_pcicfg(bank, 0x91c + i, 0x07, 0x05, 27, is_peg);
+}
diff --git a/src/northbridge/intel/haswell/haswell.h b/src/northbridge/intel/haswell/haswell.h
index 1b29f6baf0..30b4abd0a7 100644
--- a/src/northbridge/intel/haswell/haswell.h
+++ b/src/northbridge/intel/haswell/haswell.h
@@ -34,6 +34,9 @@ void haswell_early_initialization(void);
 void haswell_late_initialization(void);
 void haswell_unhide_peg(void);
 
+void dmi_early_init(void);
+void peg_dmi_recipe(const bool is_peg, const pci_devfn_t dev);
+
 void report_platform_info(void);
 
 struct acpi_rsdp;
diff --git a/src/northbridge/intel/haswell/native_raminit/raminit_native.c b/src/northbridge/intel/haswell/native_raminit/raminit_native.c
index 1aafdf8659..0938e026e3 100644
--- a/src/northbridge/intel/haswell/native_raminit/raminit_native.c
+++ b/src/northbridge/intel/haswell/native_raminit/raminit_native.c
@@ -1,7 +1,19 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
 #include <console/console.h>
+#include <northbridge/intel/haswell/haswell.h>
 #include <northbridge/intel/haswell/raminit.h>
+#include <types.h>
+
+static bool early_init_native(int s3resume)
+{
+	printk(BIOS_DEBUG, "Starting native platform initialisation\n");
+
+	if (!CONFIG(INTEL_LYNXPOINT_LP))
+		dmi_early_init();
+
+	return false;
+}
 
 void perform_raminit(const int s3resume)
 {
@@ -9,6 +21,9 @@ void perform_raminit(const int s3resume)
 	 * See, this function's name is a lie. There are more things to
 	 * do that memory initialisation, but they are relatively easy.
 	 */
+	const bool cpu_replaced = early_init_native(s3resume);
+
+	(void)cpu_replaced;
 
 	/** TODO: Implement the required magic **/
 	die("NATIVE RAMINIT: More Magic (tm) required.\n");
diff --git a/src/northbridge/intel/haswell/vcu_mailbox.c b/src/northbridge/intel/haswell/vcu_mailbox.c
new file mode 100644
index 0000000000..aead144023
--- /dev/null
+++ b/src/northbridge/intel/haswell/vcu_mailbox.c
@@ -0,0 +1,147 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <assert.h>
+#include <console/console.h>
+#include <delay.h>
+#include <northbridge/intel/haswell/haswell.h>
+#include <northbridge/intel/haswell/vcu_mailbox.h>
+#include <stdint.h>
+
+/*
+ * This is a library for the VCU (Validation Control Unit) mailbox. This
+ * mailbox is primarily used to adjust some magic PCIe tuning parameters.
+ *
+ * There are two revisions of the VCU mailbox. Rev1 is specific to Haswell
+ * stepping A0, and all other steppings use Rev2. Haswell stepping A0 CPUs
+ * are early Engineering Samples with undocumented errata, and most likely
+ * need special microcode updates to boot. Thus, the code does not support
+ * VCU mailbox Rev1, because no one should need it anymore.
+ */
+
+#define VCU_MAILBOX_INTERFACE	0x6c00
+#define VCU_MAILBOX_DATA	0x6c04
+
+#define VCU_RUN_BUSY		(1 << 31)
+
+enum vcu_opcode {
+	VCU_OPCODE_READ_VCU_API_VER_ID	= 0x01,
+	VCU_OPCODE_OPEN_SEQ		= 0x02,
+	VCU_OPCODE_CLOSE_SEQ		= 0x03,
+	VCU_OPCODE_READ_DATA		= 0x07,
+	VCU_OPCODE_WRITE_DATA		= 0x08,
+	VCU_OPCODE_READ_CSR		= 0x13,
+	VCU_OPCODE_WRITE_CSR		= 0x14,
+	VCU_OPCODE_READ_MMIO		= 0x15,
+	VCU_OPCODE_WRITE_MMIO		= 0x16,
+};
+
+enum vcu_sequence {
+	SEQ_ID_READ_CSR		= 0x1,
+	SEQ_ID_WRITE_CSR	= 0x2,
+	SEQ_ID_READ_MMIO	= 0x3,
+	SEQ_ID_WRITE_MMIO	= 0x4,
+};
+
+#define VCU_RESPONSE_MASK		0xffff
+#define VCU_RESPONSE_SUCCESS		0x40
+#define VCU_RESPONSE_BUSY		0x80
+#define VCU_RESPONSE_THREAD_UNAVAILABLE	0x82
+#define VCU_RESPONSE_ILLEGAL		0x90
+
+/* FIXME: Use timer API */
+static void send_vcu_command(const enum vcu_opcode opcode, const uint32_t data)
+{
+	for (unsigned int i = 0; i < 10; i++) {
+		mchbar_write32(VCU_MAILBOX_DATA, data);
+		mchbar_write32(VCU_MAILBOX_INTERFACE, opcode | VCU_RUN_BUSY);
+		uint32_t vcu_interface;
+		for (unsigned int j = 0; j < 100; j++) {
+			vcu_interface = mchbar_read32(VCU_MAILBOX_INTERFACE);
+			if (!(vcu_interface & VCU_RUN_BUSY))
+				break;
+
+			udelay(10);
+		}
+		if (vcu_interface & VCU_RUN_BUSY)
+			continue;
+
+		if ((vcu_interface & VCU_RESPONSE_MASK) == VCU_RESPONSE_SUCCESS)
+			return;
+	}
+	printk(BIOS_ERR, "VCU: Failed to send command\n");
+}
+
+static enum vcu_opcode get_register_opcode(enum vcu_sequence seq)
+{
+	switch (seq) {
+	case SEQ_ID_READ_CSR:
+		return VCU_OPCODE_READ_CSR;
+	case SEQ_ID_WRITE_CSR:
+		return VCU_OPCODE_WRITE_CSR;
+	case SEQ_ID_READ_MMIO:
+		return VCU_OPCODE_READ_MMIO;
+	case SEQ_ID_WRITE_MMIO:
+		return VCU_OPCODE_WRITE_MMIO;
+	default:
+		return dead_code_t(enum vcu_opcode);
+	}
+}
+
+static enum vcu_opcode get_data_opcode(enum vcu_sequence seq)
+{
+	switch (seq) {
+	case SEQ_ID_READ_CSR:
+	case SEQ_ID_READ_MMIO:
+		return VCU_OPCODE_READ_DATA;
+	case SEQ_ID_WRITE_CSR:
+	case SEQ_ID_WRITE_MMIO:
+		return VCU_OPCODE_WRITE_DATA;
+	default:
+		return dead_code_t(enum vcu_opcode);
+	}
+}
+
+static uint32_t send_vcu_sequence(uint32_t addr, enum vcu_sequence seq, uint32_t wr_data)
+{
+	send_vcu_command(VCU_OPCODE_OPEN_SEQ, seq);
+
+	send_vcu_command(get_register_opcode(seq), addr);
+
+	send_vcu_command(get_data_opcode(seq), wr_data);
+
+	const uint32_t rd_data = mchbar_read32(VCU_MAILBOX_DATA);
+
+	send_vcu_command(VCU_OPCODE_CLOSE_SEQ, seq);
+
+	return rd_data;
+}
+
+uint32_t vcu_read_csr(uint32_t addr)
+{
+	return send_vcu_sequence(addr, SEQ_ID_READ_CSR, 0);
+}
+
+void vcu_write_csr(uint32_t addr, uint32_t data)
+{
+	send_vcu_sequence(addr, SEQ_ID_WRITE_CSR, data);
+}
+
+void vcu_update_csr(uint32_t addr, uint32_t andvalue, uint32_t orvalue)
+{
+	vcu_write_csr(addr, (vcu_read_csr(addr) & andvalue) | orvalue);
+}
+
+uint32_t vcu_read_mmio(uint32_t addr)
+{
+	return send_vcu_sequence(addr, SEQ_ID_READ_MMIO, 0);
+}
+
+void vcu_write_mmio(uint32_t addr, uint32_t data)
+{
+	send_vcu_sequence(addr, SEQ_ID_WRITE_MMIO, data);
+}
+
+void vcu_update_mmio(uint32_t addr, uint32_t andvalue, uint32_t orvalue)
+{
+	vcu_write_mmio(addr, (vcu_read_mmio(addr) & andvalue) | orvalue);
+}
diff --git a/src/northbridge/intel/haswell/vcu_mailbox.h b/src/northbridge/intel/haswell/vcu_mailbox.h
new file mode 100644
index 0000000000..ba0a62e486
--- /dev/null
+++ b/src/northbridge/intel/haswell/vcu_mailbox.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef HASWELL_VCU_MAILBOX_H
+#define HASWELL_VCU_MAILBOX_H
+
+#include <stdint.h>
+
+uint32_t vcu_read_csr(uint32_t addr);
+void vcu_write_csr(uint32_t addr, uint32_t data);
+void vcu_update_csr(uint32_t addr, uint32_t andvalue, uint32_t orvalue);
+
+uint32_t vcu_read_mmio(uint32_t addr);
+void vcu_write_mmio(uint32_t addr, uint32_t data);
+void vcu_update_mmio(uint32_t addr, uint32_t andvalue, uint32_t orvalue);
+
+#endif /* HASWELL_VCU_MAILBOX_H */
diff --git a/src/southbridge/intel/lynxpoint/Makefile.inc b/src/southbridge/intel/lynxpoint/Makefile.inc
index 02022d348d..b8503ac8bc 100644
--- a/src/southbridge/intel/lynxpoint/Makefile.inc
+++ b/src/southbridge/intel/lynxpoint/Makefile.inc
@@ -37,6 +37,8 @@ bootblock-y += early_pch.c
 romstage-y += early_usb.c early_me.c me_status.c early_pch.c
 romstage-y += pmutil.c
 
+romstage-$(CONFIG_USE_NATIVE_RAMINIT) += early_pch_native.c
+
 ifeq ($(CONFIG_INTEL_LYNXPOINT_LP),y)
 romstage-y += lp_gpio.c
 ramstage-y += lp_gpio.c
diff --git a/src/southbridge/intel/lynxpoint/early_pch_native.c b/src/southbridge/intel/lynxpoint/early_pch_native.c
new file mode 100644
index 0000000000..c28ddfcf5d
--- /dev/null
+++ b/src/southbridge/intel/lynxpoint/early_pch_native.c
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <console/console.h>
+#include <device/pci_ops.h>
+#include <southbridge/intel/lynxpoint/pch.h>
+#include <types.h>
+
+void pch_dmi_setup_physical_layer(void)
+{
+	/* FIXME: We need to make sure the SA supports Gen2 as well */
+	if ((RCBA32(0x21a4) & 0x0f) == 0x02) {
+		/* Set Gen 2 Common Clock N_FTS */
+		RCBA32_AND_OR(0x2340, ~0x00ff0000, 0x3a << 16);
+
+		/* Set Target Link Speed to DMI Gen2 */
+		RCBA8_AND_OR(DLCTL2, ~0x07, 0x02);
+	}
+}
+
+#define VC_ACTIVE	(1U << 31)
+
+#define VCNEGPND	(1 << 1)
+
+void pch_dmi_tc_vc_mapping(const u32 vc0, const u32 vc1, const u32 vcp, const u32 vcm)
+{
+	printk(BIOS_DEBUG, "Programming PCH DMI VC/TC mappings...\n");
+
+	RCBA32_AND_OR(CIR0050, ~(0xf << 20), 2 << 20);
+	if (vcp & VC_ACTIVE)
+		RCBA32_OR(CIR0050, 1 << 19 | 1 << 17);
+
+	RCBA32(CIR0050);	/* Posted Write */
+
+	/* Use the same virtual channel mapping on both ends of the DMI link */
+	RCBA32(V0CTL) = vc0;
+	RCBA32(V1CTL) = vc1;
+	RCBA32(V1CTL);		/* Posted Write */
+	RCBA32(VPCTL) = vcp;
+	RCBA32(VPCTL);		/* Posted Write */
+	RCBA32(VMCTL) = vcm;
+
+	/* Lock the registers */
+	RCBA32_OR(CIR0050, 1U << 31);
+	RCBA32(CIR0050);	/* Posted Write */
+
+	printk(BIOS_DEBUG, "Waiting for PCH DMI VC negotiation... ");
+	do {} while (RCBA16(V0STS) & VCNEGPND);
+	do {} while (RCBA16(V1STS) & VCNEGPND);
+	do {} while (RCBA16(VPSTS) & VCNEGPND);
+	do {} while (RCBA16(VMSTS) & VCNEGPND);
+	printk(BIOS_DEBUG, "done!\n");
+}
diff --git a/src/southbridge/intel/lynxpoint/pch.h b/src/southbridge/intel/lynxpoint/pch.h
index 7d9fc6d6af..b5e0c2a830 100644
--- a/src/southbridge/intel/lynxpoint/pch.h
+++ b/src/southbridge/intel/lynxpoint/pch.h
@@ -113,6 +113,9 @@ enum pch_platform_type {
 	PCH_TYPE_ULT	 = 5,
 };
 
+void pch_dmi_setup_physical_layer(void);
+void pch_dmi_tc_vc_mapping(u32 vc0, u32 vc1, u32 vcp, u32 vcm);
+
 void usb_ehci_sleep_prepare(pci_devfn_t dev, u8 slp_typ);
 void usb_ehci_disable(pci_devfn_t dev);
 void usb_xhci_sleep_prepare(pci_devfn_t dev, u8 slp_typ);
@@ -406,9 +409,10 @@ void mainboard_config_rcba(void);
 
 /* Southbridge IO BARs */
 
+#define PMBASE			0x40
 #define GPIOBASE		0x48
 
-#define PMBASE		0x40
+#define CIR0050		0x0050	/* 32bit */
 
 #define RPC		0x0400	/* 32bit */
 #define RPFN		0x0404	/* 32bit */
@@ -431,6 +435,20 @@ void mainboard_config_rcba(void);
 #define IOTR2		0x1e90	/* 64bit */
 #define IOTR3		0x1e98	/* 64bit */
 
+#define V0CTL		0x2014	/* 32bit */
+#define V0STS		0x201a	/* 16bit */
+
+#define V1CTL		0x2020	/* 32bit */
+#define V1STS		0x2026	/* 16bit */
+
+#define VPCTL		0x2030	/* 32bit */
+#define VPSTS		0x2038	/* 16bit */
+
+#define VMCTL		0x2040	/* 32bit */
+#define VMSTS		0x2048	/* 16bit */
+
+#define DLCTL2		0x21b0
+
 #define TCTL		0x3000	/*  8bit */
 
 #define NOINT		0
-- 
2.39.2