diff --git a/src/northbridge/intel/e7505/Kconfig b/src/northbridge/intel/e7505/Kconfig
index 4a54bc0..95e8de7 100644
--- a/src/northbridge/intel/e7505/Kconfig
+++ b/src/northbridge/intel/e7505/Kconfig
@@ -10,5 +10,6 @@
 	select NO_ECAM_MMCONF_SUPPORT
 	select HAVE_DEBUG_RAM_SETUP
 	select NO_CBFS_MCACHE
+	select SMM_TSEG
 
 endif
diff --git a/src/northbridge/intel/e7505/e7505.h b/src/northbridge/intel/e7505/e7505.h
index b429c70..ed596c9 100644
--- a/src/northbridge/intel/e7505/e7505.h
+++ b/src/northbridge/intel/e7505/e7505.h
@@ -7,6 +7,11 @@
 #ifndef NORTHBRIDGE_INTEL_E7505_E7505_H
 #define NORTHBRIDGE_INTEL_E7505_E7505_H
 
+#include <types.h>
+
+size_t northbridge_get_tseg_size(void);
+uintptr_t northbridge_get_tseg_base(void);
+
 /************  D0:F0 ************/
 // Register offsets
 #define SMRBASE		0x14	/* System Memory RCOMP Base Address Register, 32 bit? */
@@ -28,8 +33,6 @@
 #define DRC		0x7C	/* DRAM Controller Mode register, 32 bit */
 #define DRDCTL		0x80	/* DRAM Read Timing Control register, 16 bit? (if similar to 855PM) */
 #define CKDIS		0x8C	/* Clock disable register, 8 bit */
-#define SMRAMC		0x9D
-#define ESMRAMC		0x9E
 #define APSIZE		0xB4
 #define TOLM		0xC4	/* Top of Low Memory register, 16 bit */
 #define REMAPBASE	0xC6	/* Remap Base Address register, 16 bit */
@@ -38,6 +41,22 @@
 #define DVNP		0xE0	/* Device Not Present, 16 bit */
 #define MCHTST		0xF4	/* MCH Test Register, 32 bit? (if similar to 855PM) */
 
+#define SMRAMC		0x9D
+#define C_BASE_SEG	((0 << 2) | (1 << 1) | (0 << 0))
+#define G_SMRAME	(1 << 3)
+#define	D_LCK		(1 << 4)
+#define D_CLS		(1 << 5)
+#define D_OPEN		(1 << 6)
+
+#define ESMRAMC		0x9E
+#define T_EN		(1 << 0)
+#define	TSEG_SZ_128K	(0 << 1)
+#define TSEG_SZ_256K	(1 << 1)
+#define TSEG_SZ_512K	(2 << 1)
+#define TSEG_SZ_1M	(3 << 1)
+#define TSEG_SZ_MASK	TSEG_SZ_1M
+#define H_SMRAME	(1 << 7)
+
 // CAS# Latency bits in the DRAM Timing (DRT) register
 #define DRT_CAS_2_5		(0<<4)
 #define DRT_CAS_2_0		(1<<4)
diff --git a/src/northbridge/intel/e7505/memmap.c b/src/northbridge/intel/e7505/memmap.c
index 0d90175..47c3b10 100644
--- a/src/northbridge/intel/e7505/memmap.c
+++ b/src/northbridge/intel/e7505/memmap.c
@@ -5,37 +5,93 @@
 
 #include <arch/romstage.h>
 #include <cbmem.h>
+#include <cpu/intel/smm_reloc.h>
 #include <cpu/x86/mtrr.h>
+#include <cpu/x86/smm.h>
 #include <device/pci_ops.h>
 #include <program_loading.h>
 #include <stdint.h>
 
 #include "e7505.h"
 
-uintptr_t cbmem_top_chipset(void)
+#define HOST_BRIDGE PCI_DEV(0, 0, 0)
+
+static uintptr_t top_of_low_ram(void)
 {
-	const pci_devfn_t mch = PCI_DEV(0, 0, 0);
 	uintptr_t tolm;
 
 	/* This is at 128 MiB boundary. */
-	tolm = pci_read_config16(mch, TOLM) >> 11;
+	tolm = pci_read_config16(HOST_BRIDGE, TOLM) >> 11;
 	tolm <<= 27;
-
 	return tolm;
 }
 
-void northbridge_write_smram(u8 smram);
-
-void northbridge_write_smram(u8 smram)
+size_t northbridge_get_tseg_size(void)
 {
-	const pci_devfn_t mch = PCI_DEV(0, 0, 0);
-	pci_write_config8(mch, SMRAMC, smram);
+	const uint8_t esmramc = pci_read_config8(HOST_BRIDGE, ESMRAMC);
+
+	if (!(esmramc & T_EN))
+		return 0;
+
+	switch ((esmramc & TSEG_SZ_MASK) >> 1) {
+	case 0:
+		return 128 * KiB;
+	case 1:
+		return 256 * KiB;
+	case 2:
+		return 512 * KiB;
+	case 3:
+	default:
+		return 1 * MiB;
+	}
+}
+
+uintptr_t northbridge_get_tseg_base(void)
+{
+	uintptr_t tolm = top_of_low_ram();
+
+	/* subtract TSEG size */
+	tolm -= northbridge_get_tseg_size();
+	return tolm;
+}
+
+void smm_region(uintptr_t *start, size_t *size)
+{
+	*start = northbridge_get_tseg_base();
+	*size = northbridge_get_tseg_size();
+}
+
+uintptr_t cbmem_top_chipset(void)
+{
+	return northbridge_get_tseg_base();
+}
+
+void smm_open(void)
+{
+	/* Set D_OPEN */
+	pci_write_config8(HOST_BRIDGE, SMRAMC, D_OPEN | G_SMRAME | C_BASE_SEG);
+}
+
+void smm_close(void)
+{
+	/* Clear D_OPEN */
+	pci_write_config8(HOST_BRIDGE, SMRAMC, G_SMRAME | C_BASE_SEG);
+}
+
+void smm_lock(void)
+{
+	/*
+	 * LOCK the SMM memory window and enable normal SMM.
+	 * After running this function, only a full reset can
+	 * make the SMM registers writable again.
+	 */
+	printk(BIOS_DEBUG, "Locking SMM.\n");
+
+	pci_write_config8(HOST_BRIDGE, SMRAMC, D_LCK | G_SMRAME | C_BASE_SEG);
 }
 
 void fill_postcar_frame(struct postcar_frame *pcf)
 {
-	uintptr_t top_of_ram;
-
 	/*
 	 * Choose to NOT set ROM as WP cacheable here.
 	 * Timestamps indicate the CPU this northbridge code is
@@ -45,11 +101,6 @@
 
 	pcf->skip_common_mtrr = 1;
 
-	/* Cache RAM as WB from 0 -> CACHE_TMP_RAMTOP. */
-	postcar_frame_add_mtrr(pcf, 0, CACHE_TMP_RAMTOP, MTRR_TYPE_WRBACK);
-
-	/* Cache CBMEM region as WB. */
-	top_of_ram = (uintptr_t)cbmem_top();
-	postcar_frame_add_mtrr(pcf, top_of_ram - 8*MiB, 8*MiB,
-		MTRR_TYPE_WRBACK);
+	/* Cache RAM as WB from 0 -> TOLM. */
+	postcar_frame_add_mtrr(pcf, top_of_low_ram(), CACHE_TMP_RAMTOP, MTRR_TYPE_WRBACK);
 }
diff --git a/src/northbridge/intel/e7505/northbridge.c b/src/northbridge/intel/e7505/northbridge.c
index 08ac122..cc7f85d 100644
--- a/src/northbridge/intel/e7505/northbridge.c
+++ b/src/northbridge/intel/e7505/northbridge.c
@@ -42,6 +42,9 @@
 	ram_resource_kb(dev, idx++, 0, tolmk);
 	mmio_resource_kb(dev, idx++, 0xa0000 / KiB, (0xc0000 - 0xa0000) / KiB);
 
+	uintptr_t tseg_memory_base = northbridge_get_tseg_base();
+	size_t tseg_memory_size = northbridge_get_tseg_size();
+	mmio_resource_kb(dev, idx++, tseg_memory_base / KiB, tseg_memory_size / KiB);
 
 	ASSERT(tom == remapbase);
 	upper_ram_end(dev, idx++, remaplimit);
diff --git a/src/northbridge/intel/e7505/raminit.c b/src/northbridge/intel/e7505/raminit.c
index 5387d4d..2b81d37 100644
--- a/src/northbridge/intel/e7505/raminit.c
+++ b/src/northbridge/intel/e7505/raminit.c
@@ -1687,6 +1687,8 @@
 	return !!(dword & DRC_DONE);
 }
 
+#define HOST_BRIDGE PCI_DEV(0, 0, 0)
+
 void sdram_initialize(void)
 {
 	static const struct mem_controller memctrl[] = {
@@ -1714,5 +1716,9 @@
 		timestamp_add_now(TS_INITRAM_END);
 	}
 
+
+	if (CONFIG(SMM_TSEG))
+		pci_write_config8(HOST_BRIDGE, ESMRAMC, TSEG_SZ_1M | T_EN);
+
 	printk(BIOS_DEBUG, "SDRAM is up.\n");
 }