Initial Intel 440BX RAM initialization framework.

This does _not_ fully work, yet. You will _not_ be able to boot any
payload with this code, yet.

Add missing license headers.

Base the northbridge.c file on the Intel 855PM version, that comes
closer to what we want.

The raminit.c file is written from scratch and hardcodes several
values for now. This needs to be fixed later by reading the
correct values via SPD.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Stefan Reinauer <stepan@coresystems.de>



git-svn-id: svn://svn.coreboot.org/coreboot/trunk@2576 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

1 files changed, 504 insertions, 363 deletions

diff --git a/src/northbridge/intel/i440bx/raminit.c b/src/northbridge/intel/i440bx/raminit.c
index 737f2bf458..a4724323ae 100644
--- a/src/northbridge/intel/i440bx/raminit.c
+++ b/src/northbridge/intel/i440bx/raminit.c
@@ -1,399 +1,540 @@
-#include <cpu/x86/mtrr.h>
-#include "raminit.h"
-
-/*
-This software and ancillary information (herein called SOFTWARE )
-called LinuxBIOS          is made available under the terms described
-here.  The SOFTWARE has been approved for release with associated
-LA-CC Number 00-34   .  Unless otherwise indicated, this SOFTWARE has
-been authored by an employee or employees of the University of
-California, operator of the Los Alamos National Laboratory under
-Contract No. W-7405-ENG-36 with the U.S. Department of Energy.  The
-U.S. Government has rights to use, reproduce, and distribute this
-SOFTWARE.  The public may copy, distribute, prepare derivative works
-and publicly display this SOFTWARE without charge, provided that this
-Notice and any statement of authorship are reproduced on all copies.
-Neither the Government nor the University makes any warranty, express 
-or implied, or assumes any liability or responsibility for the use of
-this SOFTWARE.  If SOFTWARE is modified to produce derivative works,
-such modified SOFTWARE should be clearly marked, so as not to confuse
-it with the version available from LANL.
- */
-/* Copyright 2000, Ron Minnich, Advanced Computing Lab, LANL
- * rminnich@lanl.gov
- */
 /*
- * 11/26/02 - kevinh@ispiri.com - The existing comments implied that
- * this didn't work yet.  Therefore, I've updated it so that it works
- * correctly - at least on my VIA epia motherboard.  64MB DIMM in slot 0.
+ * This file is part of the LinuxBIOS project.
+ *
+ * Copyright (C) 2007 Uwe Hermann <uwe@hermann-uwe.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  */
 
-/* Added automatic detection of first equipped bank and its MA mapping type.
- * (Rest of configuration is done in C)
- * 5/19/03 by SONE Takeshi <ts1@tsn.or.jp>
- */
-/* converted to C 9/2003 Ron Minnich */
+#include <spd.h>
+#include <sdram_mode.h>
+#include <delay.h>
+#include "i440bx.h"
 
-/* Modified for the i440bx Richard Smith 01/2005 */
+/*-----------------------------------------------------------------------------
+Macros and definitions.
+-----------------------------------------------------------------------------*/
 
-/* Set to 1 if your DIMMs are PC133 Note that I'm assuming CPU's FSB
- * frequency is 133MHz. If your CPU runs at another bus speed, you
- * might need to change some of register values.
- */
-#ifndef DIMM_PC133
-#define DIMM_PC133 0
-#endif
+/* Uncomment this to enable debugging output. */
+#define DEBUG_RAM_SETUP 1
 
-// Set to 1 if your DIMMs are CL=2
-#ifndef DIMM_CL2
-#define DIMM_CL2 0
+/* Debugging macros. */
+#if defined(DEBUG_RAM_SETUP)
+#define PRINT_DEBUG(x)		print_debug(x)
+#define PRINT_DEBUG_HEX8(x)	print_debug_hex8(x)
+#define PRINT_DEBUG_HEX16(x)	print_debug_hex16(x)
+#define PRINT_DEBUG_HEX32(x)	print_debug_hex32(x)
+#define DUMPNORTH()		dump_pci_device(PCI_DEV(0, 0, 0))
+#else
+#define PRINT_DEBUG_(x)
+#define PRINT_DEBUG_HEX8(x)
+#define PRINT_DEBUG_HEX16(x)
+#define PRINT_DEBUG_HEX32(x)
+#define DUMPNORTH()
 #endif
 
-void dimms_read(unsigned long x) 
-{
-	uint8_t c;
-	unsigned long eax; 
-	volatile unsigned long y;
-	eax =  x;
-	for(c = 0; c < 6; c++) {
-		y = * (volatile unsigned long *) eax;
-		eax += 0x10000000;
-	}
-}
+/* SDRAMC[7:5] - SDRAM Mode Select (SMS). */
+#define RAM_COMMAND_NORMAL	0x0
+#define RAM_COMMAND_NOP		0x1
+#define RAM_COMMAND_PRECHARGE	0x2
+#define RAM_COMMAND_MRS		0x3
+#define RAM_COMMAND_CBR		0x4
 
-void dimms_write(int x) 
-{
-	uint8_t c;
-	unsigned long eax = x;
-	for(c = 0; c < 6; c++) {
-		*(volatile unsigned long *) eax = 0;
-		eax += 0x10000000;
-	}
-}
+/* Map the JEDEC SPD refresh rates (array index) to 440BX refresh rates as
+ * defined in DRAMC[2:0].
+ *
+ * [0] == Normal        15.625 us ->  15.6 us
+ * [1] == Reduced(.25X)    3.9 us ->   7.8 ns
+ * [2] == Reduced(.5X)     7.8 us ->   7.8 us
+ * [3] == Extended(2x)    31.3 us ->  31.2 us
+ * [4] == Extended(4x)    62.5 us ->  62.4 us
+ * [5] == Extended(8x)     125 us -> 124.8 us
+ */
+static const uint32_t refresh_rate_map[] = {
+	1, 5, 5, 2, 3, 4
+};
 
+/* Table format: register, bitmask, value. */
+static const long register_values[] = {
+	/* NBXCFG - NBX Configuration Register
+	 * 0x50
+	 *
+	 * [31:24] SDRAM Row Without ECC
+	 *         0 = ECC components are populated in this row
+	 *         1 = ECC components are not populated in this row
+	 * [23:19] Reserved
+	 * [18:18] Host Bus Fast Data Ready Enable (HBFDRE)
+	 *         Assertion of DRAM data on host bus occurs...
+	 *         0 = ...one clock after sampling snoop results (default)
+	 *         1 = ...on the same clock the snoop result is being sampled
+	 *             (this mode is faster by one clock cycle)
+	 * [17:17] ECC - EDO static Drive mode
+	 *         0 = Normal mode (default)
+	 *         1 = ECC signals are always driven
+	 * [16:16] IDSEL_REDIRECT
+	 *         0 = IDSEL1 is allocated to this bridge (default)
+	 *         1 = IDSEL7 is allocated to this bridge
+	 * [15:15] WSC# Handshake Disable
+	 *         1 = Uni-processor mode
+	 *         0 = Dual-processor mode with external IOAPIC (default)
+	 * [14:14] Intel Reserved
+	 * [13:12] Host/DRAM Frequency
+	 *         00 = 100 MHz
+	 *         01 = Reserved
+	 *         10 = 66 MHz
+	 *         11 = Reserved
+	 * [11:11] AGP to PCI Access Enable
+	 *         1 = Enable
+	 *         0 = Disable
+	 * [10:10] PCI Agent to Aperture Access Disable
+	 *         1 = Disable
+	 *         0 = Enable (default)
+	 * [09:09] Aperture Access Global Enable
+	 *         1 = Enable
+	 *         0 = Disable
+	 * [08:07] DRAM Data Integrity Mode (DDIM)
+	 *         00 = Non-ECC
+	 *         01 = EC-only
+	 *         10 = ECC Mode
+	 *         11 = ECC Mode with hardware scrubbing enabled
+	 * [06:06] ECC Diagnostic Mode Enable (EDME)
+	 *         1 = Enable
+	 *         0 = Normal operation mode (default)
+	 * [05:05] MDA Present (MDAP)
+	 *         Works in conjunction with the VGA_EN bit.
+	 *         VGA_EN MDAP
+	 *           0     x   All VGA cycles are sent to PCI
+	 *           1     0   All VGA cycles are sent to AGP
+	 *           1     1   All VGA cycles are sent to AGP, except for
+	 *                     cycles in the MDA range.
+	 * [04:04] Reserved
+	 * [03:03] USWC Write Post During I/O Bridge Access Enable (UWPIO)
+	 *         1 = Enable
+	 *         0 = Disable
+	 * [02:02] In-Order Queue Depth (IOQD)
+	 *         1 = In-order queue = maximum
+	 *         0 = A7# is sampled asserted (i.e., 0)
+	 * [01:00] Reserved
+	 */
+	// TODO
+	NBXCFG, 0x00000000, 0xff00a00c,
 
+	/* DRAMC - DRAM Control Register
+	 * 0x57
+	 *
+	 * [7:6] Reserved
+	 * [5:5] Module Mode Configuration (MMCONFIG)
+	 *       TODO
+	 * [4:3] DRAM Type (DT)
+	 *       00 = EDO
+	 *       01 = SDRAM
+	 *       10 = Registered SDRAM
+	 *       11 = Reserved
+	 *       Note: EDO, SDRAM and Registered SDRAM cannot be mixed.
+	 * [2:0] DRAM Refresh Rate (DRR)
+	 *       000 = Refresh disabled
+	 *       001 = 15.6 us
+	 *       010 = 31.2 us
+	 *       011 = 62.4 us
+	 *       100 = 124.8 us
+	 *       101 = 249.6 us
+	 *       110 = Reserved
+	 *       111 = Reserved
+	 */
+	/* Choose SDRAM (not registered), and disable refresh for now. */
+	DRAMC, 0x00, 0x8,
 
-#ifdef DEBUG_SETNORTHB
-void setnorthb(device_t north, uint8_t reg, uint8_t val) 
-{
-	print_debug("setnorth: reg ");
-	print_debug_hex8(reg);
-	print_debug(" to ");
-	print_debug_hex8(val);
-	print_debug("\r\n");
-	pci_write_config8(north, reg, val);
-}
-#else
-#define setnorthb pci_write_config8
-#endif
+	/*
+	 * PAM[6:0] - Programmable Attribute Map Registers
+	 *
+	 * 0x59 [3:0] Reserved
+	 * 0x59 [5:4] 0xF0000 - 0xFFFFF BIOS area
+	 * 0x5a [1:0] 0xC0000 - 0xC3FFF ISA add-on BIOS
+	 * 0x5a [5:4] 0xC4000 - 0xC7FFF ISA add-on BIOS
+	 * 0x5b [1:0] 0xC8000 - 0xCBFFF ISA add-on BIOS
+	 * 0x5b [5:4] 0xCC000 - 0xCFFFF ISA add-on BIOS
+	 * 0x5c [1:0] 0xD0000 - 0xD3FFF ISA add-on BIOS
+	 * 0x5c [5:4] 0xD4000 - 0xD7FFF ISA add-on BIOS
+	 * 0x5d [1:0] 0xD8000 - 0xDBFFF ISA add-on BIOS
+	 * 0x5d [5:4] 0xDC000 - 0xDFFFF ISA add-on BIOS
+	 * 0x5e [1:0] 0xE0000 - 0xE3FFF BIOS entension
+	 * 0x5e [5:4] 0xE4000 - 0xE7FFF BIOS entension
+	 * 0x5f [1:0] 0xE8000 - 0xEBFFF BIOS entension
+	 * 0x5f [5:4] 0xEC000 - 0xEFFFF BIOS entension
+	 *
+	 * Bit assignment:
+	 * 00 = DRAM Disabled (all access goes to memory mapped I/O space)
+	 * 01 = Read Only (Reads to DRAM, writes to memory mapped I/O space)
+	 * 10 = Write Only (Writes to DRAM, reads to memory mapped I/O space)
+	 * 11 = Read/Write (all access goes to DRAM)
+	 */
+	// TODO
+	PAM0, 0x00000000, 0x00,
+	PAM1, 0x00000000, 0x00,
+	PAM2, 0x00000000, 0x00,
+	PAM3, 0x00000000, 0x00,
+	PAM4, 0x00000000, 0x00,
+	PAM5, 0x00000000, 0x00,
+	PAM6, 0x00000000, 0x00,
+
+	/* DRB[0:7] - DRAM Row Boundary Registers
+	 * 0x60 - 0x67
+	 *
+	 * An array of 8 byte registers, which hold the ending memory address
+	 * assigned to each pair of DIMMs, in 8MB granularity.   
+	 *
+	 * 0x60 DRB0 = Total memory in row0 (in 8 MB)
+	 * 0x61 DRB1 = Total memory in row0+1 (in 8 MB)
+	 * 0x62 DRB2 = Total memory in row0+1+2 (in 8 MB)
+	 * 0x63 DRB3 = Total memory in row0+1+2+3 (in 8 MB)
+	 * 0x64 DRB4 = Total memory in row0+1+2+3+4 (in 8 MB)
+	 * 0x65 DRB5 = Total memory in row0+1+2+3+4+5 (in 8 MB)
+	 * 0x66 DRB6 = Total memory in row0+1+2+3+4+5+6 (in 8 MB)
+	 * 0x67 DRB7 = Total memory in row0+1+2+3+4+5+6+7 (in 8 MB)
+	 */
+	// TODO
+	DRB0, 0x00, 0x00,
+	DRB1, 0x00, 0x00,
+	DRB2, 0x00, 0x00,
+	DRB3, 0x00, 0x00,
+	DRB4, 0x00, 0x00,
+	DRB5, 0x00, 0x00,
+	DRB6, 0x00, 0x00,
+	DRB7, 0x00, 0x00,
+
+	/* FDHC - Fixed DRAM Hole Control Register
+	 * 0x68
+	 *
+	 * Controls two fixed DRAM holes: 512 KB - 640 KB and 15 MB - 16 MB.
+	 *
+	 * [7:6] Hole Enable (HEN)
+	 *       00 = None
+	 *       01 = 512 KB - 640 KB (128 KB)
+	 *       10 = 15 MB - 16 MB (1 MB)
+	 *       11 = Reserved
+	 * [5:0] Reserved
+	 */
+	/* No memory holes. */
+	FDHC, 0x00, 0x00,
+
+	/* RPS - SDRAM Row Page Size Register
+	 * 0x74 - 0x75
+	 *
+	 * Sets the row page size for SDRAM. For EDO memory, the page
+	 * size is fixed at 2 KB.
+	 *
+	 * [15:0] Page Size (PS)
+	 *        TODO
+	 */
+	// TODO
+	RPS, 0x0000, 0x0000,
+
+	/* SDRAMC - SDRAM Control Register
+	 * 0x76-0x77
+	 *
+	 * [15:10] Reserved
+	 * [09:08] Idle/Pipeline DRAM Leadoff Timing (IPDLT)
+	 *         00 = Illegal
+	 *         01 = Add a clock delay to the lead-off clock count
+	 *         10 = Illegal
+	 *         11 = Illegal
+	 * [07:05] SDRAM Mode Select (SMS)
+	 *         000 = Normal SDRAM Operation (default)
+	 *         001 = NOP Command Enable
+	 *         010 = All Banks Precharge Enable
+	 *         011 = Mode Register Set Enable
+	 *         100 = CBR Enable
+	 *         101 = Reserved
+	 *         110 = Reserved
+	 *         111 = Reserved
+	 * [04:04] SDRAMPWR
+	 *         0 = 3 DIMM configuration
+	 *         1 = 4 DIMM configuration
+	 * [03:03] Leadoff Command Timing (LCT)
+	 *         0 = 4 CS# Clock
+	 *         1 = 3 CS# Clock
+	 * [02:02] CAS# Latency (CL)
+	 *         0 = 3 DCLK CAS# latency
+	 *         1 = 2 DCLK CAS# latency
+	 * [01:01] SDRAM RAS# to CAS# Delay (SRCD)
+	 *         0 = 3 clocks between a row activate and a read or write cmd.
+	 *         1 = 2 clocks between a row activate and a read or write cmd.
+	 * [00:00] SDRAM RAS# Precharge (SRP)
+	 *         0 = 3 clocks of RAS# precharge
+	 *         1 = 2 clocks of RAS# precharge
+	 */
+	SDRAMC, 0x0000, 0x0000,
+
+	/* PGPOL - Paging Policy Register
+	 * 0x78 - 0x79
+	 *
+	 * [15:08] Banks per Row (BPR)
+	 *         TODO
+	 *         0 = 2 banks
+	 *         1 = 4 banks
+	 * [07:05] Reserved
+	 * [04:04] Intel Reserved
+	 * [03:00] DRAM Idle Timer (DIT)
+	 *         0000 = 0 clocks
+	 *         0001 = 2 clocks
+	 *         0010 = 4 clocks
+	 *         0011 = 8 clocks
+	 *         0100 = 10 clocks
+	 *         0101 = 12 clocks
+	 *         0110 = 16 clocks
+	 *         0111 = 32 clocks
+	 *         1xxx = Infinite (pages are not closed for idle condition)
+	 */
+	// TODO
+	PGPOL, 0x0000, 0xff00,
 
-void
-dumpnorth(device_t north) 
+	/* PMCR - Power Management Control Register
+	 * 0x7a
+	 *
+	 * [07:07] Power Down SDRAM Enable (PDSE)
+	 *         1 = Enable
+	 *         0 = Disable
+	 * [06:06] ACPI Control Register Enable (SCRE)
+	 *         1 = Enable
+	 *         0 = Disable (default)
+	 * [05:05] Suspend Refresh Type (SRT)
+	 *         1 = Self refresh mode
+	 *         0 = CBR fresh mode
+	 * [04:04] Normal Refresh Enable (NREF_EN)
+	 *         1 = Enable
+	 *         0 = Disable
+	 * [03:03] Quick Start Mode (QSTART)
+	 *         1 = Quick start mode for the processor is enabled
+	 * [02:02] Gated Clock Enable (GCLKEN)
+	 *         1 = Enable
+	 *         0 = Disable
+	 * [01:01] AGP Disable (AGP_DIS)
+	 *         1 = Disable
+	 *         0 = Enable
+	 * [00:00] CPU reset without PCIRST enable (CRst_En)
+	 *         1 = Enable
+	 *         0 = Disable
+	 */
+	/* Enable normal refresh and the gated clock. */
+	// TODO: Only do this later?
+	// PMCR, 0x00, 0x14,
+	// PMCR, 0x00, 0x10,
+	PMCR, 0x00, 0x00,
+};
+
+/*-----------------------------------------------------------------------------
+SDRAM configuration functions.
+-----------------------------------------------------------------------------*/
+
+/**
+ * Send the specified RAM command to all DIMMs.
+ *
+ * @param Memory controller
+ * @param TODO
+ * @param TODO
+ */
+static void do_ram_command(const struct mem_controller *ctrl,
+			   uint32_t command, uint32_t addr_offset)
 {
-	unsigned int r, c;
-	for(r = 0; ; r += 16) {
-		print_debug_hex8(r);
-		print_debug(":");
-		for(c = 0; c < 16; c++) {
-			print_debug_hex8(pci_read_config8(north, r+c));
-			print_debug(" ");
-		}
-		print_debug("\r\n");
-		if (r >= 240)
-			break;
-  }
+	int i;
+	uint16_t reg;
+
+	/* TODO: Support for multiple DIMMs. */
+
+	/* Configure the RAM command. */
+	reg = pci_read_config16(ctrl->d0, SDRAMC);
+	reg &= 0xff1f;		/* Clear bits 7-5. */
+	reg |= (uint16_t) (command << 5);
+	pci_write_config16(ctrl->d0, SDRAMC, reg);
+
+	/* RAM_COMMAND_NORMAL affects only the memory controller and
+	   doesn't need to be "sent" to the DIMMs. */
+	/* if (command == RAM_COMMAND_NORMAL) return; */
+
+	PRINT_DEBUG("    Sending RAM command 0x");
+	PRINT_DEBUG_HEX16(reg);
+	PRINT_DEBUG(" to 0x");
+	PRINT_DEBUG_HEX32(0 + addr_offset); // FIXME
+	PRINT_DEBUG("\r\n");
+
+	/* Read from (DIMM start address + addr_offset). */
+	read32(0 + addr_offset); // FIXME
 }
 
-static void sdram_set_registers(const struct mem_controller *ctrl) 
+/*-----------------------------------------------------------------------------
+DIMM-independant configuration functions.
+-----------------------------------------------------------------------------*/
+
+/**
+ * TODO.
+ *
+ * @param Memory controller
+ */
+static void spd_enable_refresh(const struct mem_controller *ctrl)
 {
-	device_t north = (device_t) 0;
-	uint8_t c, r;
-
-	print_err("vt8601 init starting\r\n");
-	north = pci_locate_device(PCI_ID(0x1106, 0x8601), 0);
-	north = 0;
-	print_debug_hex32(north);
-	print_debug(" is the north\n");
-	print_debug_hex16(pci_read_config16(north, 0));
-	print_debug(" ");
-	print_debug_hex16(pci_read_config16(north, 2));
-	print_debug("\r\n");
-	
-	/* All we are doing now is setting initial known-good values that will
-	 * be revised later as we read SPD
-	 */	
-	// memory clk enable. We are not using ECC
-	pci_write_config8(north,0x78, 0x01);
-	print_debug_hex8(pci_read_config8(north, 0x78));
-	// dram control, see the book. 
-#if DIMM_PC133
-	pci_write_config8(north,0x68, 0x52);
-#else
-	pci_write_config8(north,0x68, 0x42);
-#endif
-	// dram control, see the book. 
-	pci_write_config8(north,0x6B, 0x0c);
-	// Initial setting, 256MB in each bank, will be rewritten later.
-	pci_write_config8(north,0x5A, 0x20);
-	print_debug_hex8(pci_read_config8(north, 0x5a));
-	pci_write_config8(north,0x5B, 0x40);
-	pci_write_config8(north,0x5C, 0x60);
-	pci_write_config8(north,0x5D, 0x80);
-	pci_write_config8(north,0x5E, 0xA0);
-	pci_write_config8(north,0x5F, 0xC0);
-	// It seems we have to take care of these 2 registers as if 
-	// they are bank 6 and 7.
-	pci_write_config8(north,0x56, 0xC0);
-	pci_write_config8(north,0x57, 0xC0);
-	
-	// SDRAM in all banks
-	pci_write_config8(north,0x60, 0x3F);
-	// DRAM timing. I'm suspicious of this
-	// This is for all banks, 64 is 0,1.  65 is 2,3. 66 is 4,5.
-	// ras precharge 4T, RAS pulse 5T
-	// cas2 is 0xd6, cas3 is 0xe6
-	// we're also backing off write pulse width to 2T, so result is 0xee
-#if DIMM_CL2
-	pci_write_config8(north,0x64, 0xd4);
-	pci_write_config8(north,0x65, 0xd4);
-	pci_write_config8(north,0x66, 0xd4);
-#else // CL=3
-	pci_write_config8(north,0x64, 0xe4);
-	pci_write_config8(north,0x65, 0xe4);
-	pci_write_config8(north,0x66, 0xe4);
-#endif
+	int i, value;
+	uint8_t reg;
 
-	// dram frequency select.
-	// enable 4K pages for 64M dram. 
-#if DIMM_PC133
-	pci_write_config8(north,0x69, 0x3c);
-#else
-	pci_write_config8(north,0x69, 0xac);
-#endif
+	reg = pci_read_config8(ctrl->d0, DRAMC);
 
-	/* IMPORTANT -- disable refresh counter */
-	// refresh counter, disabled.
-	pci_write_config8(north,0x6A, 0x00);
-	
-
-	// clkenable configuration. kevinh FIXME - add precharge
-	pci_write_config8(north,0x6C, 0x00);
-	// dram read latch delay of 1 ns, MD drive 8 mA,
-	// high drive strength on MA[2:	13], we#, cas#, ras#
-	// As per Cindy Lee, set to 0x37, not 0x57
-	pci_write_config8(north,0x6D, 0x7f);
-}
+	for (i = 0; i < DIMM_SOCKETS; i++) {
+		value = spd_read_byte(ctrl->channel0[i], SPD_REFRESH);
+		if (value < 0)
+			continue;
+		reg = (reg & 0xf8) | refresh_rate_map[(value & 0x7f)];
 
-/* slot is the dram slot. Return size of side0 in lower 16-bit,
- * side1 in upper 16-bit, in units of 8MB */
-static unsigned long 
-spd_module_size(unsigned char slot) 
-{ 
-	/* for all the DRAMS, see if they are there and get the size of each
-	 * module. This is just a very early first cut at sizing.
-	 */
-	/* we may run out of registers ... */
-	unsigned int banks, rows, cols, reg;
-	unsigned int value = 0;
-	/* unsigned int module = ((0x50 + slot) << 1) + 1; */
-	unsigned int module = 0x50 + slot;
-	/* is the module there? if byte 2 is not 4, then we'll assume it 
-	 * is useless. 
-	 */
-	print_info("Slot "); 
-	print_info_hex8(slot); 
-	if (smbus_read_byte(module, 2) != 4) {
-		print_info(" is empty\r\n");
-		return 0;
-	}
-	print_info(" is SDRAM ");
-	
-	banks = smbus_read_byte(module, 17);
-	/* we're going to assume symmetric banks. Sorry. */
-	cols = smbus_read_byte(module, 4)  & 0xf;
-	rows = smbus_read_byte(module, 3)  & 0xf;
-	/* grand total. You have rows+cols addressing, * times of banks, times
-	 * width of data in bytes */
-	/* Width is assumed to be 64 bits == 8 bytes */
-	value = (1 << (cols + rows)) * banks * 8;
-	print_info_hex32(value);
-	print_info(" bytes ");
-	/* Return in 8MB units */
-	value >>= 23;
-
-	/* We should have single or double side */
-	if (smbus_read_byte(module, 5) == 2) {
-		print_info("x2");
-		value = (value << 16) | value;
+		PRINT_DEBUG("    Enabling refresh (DRAMC = 0x");
+		PRINT_DEBUG_HEX8(reg);
+		PRINT_DEBUG(") for DIMM ");
+		PRINT_DEBUG_HEX8(i);
+		PRINT_DEBUG("\r\n");
 	}
-	print_info("\r\n");
-	return value;
 
+	pci_write_config8(ctrl->d0, DRAMC, reg);
 }
 
-static int
-spd_num_chips(unsigned char slot) 
-{ 
-/*	unsigned int module = ((0x50 + slot) << 1) + 1; */
-	unsigned int module = 0x50 + slot;
-	unsigned int width;
-
-	width = smbus_read_byte(module, 13);
-	if (width == 0)
-		width = 8;
-	return 64 / width;
+/*-----------------------------------------------------------------------------
+Public interface.
+-----------------------------------------------------------------------------*/
+
+/**
+ * TODO.
+ *
+ * @param Memory controller
+ */
+static void sdram_set_registers(const struct mem_controller *ctrl)
+{
+	int i, max;
+	uint32_t reg;
+
+	PRINT_DEBUG("Northbridge prior to SDRAM init:\r\n");
+	DUMPNORTH();
+
+	max = sizeof(register_values) / sizeof(register_values[0]);
+
+	/* Set registers as specified in the register_values array. */
+	for (i = 0; i < max; i += 3) {
+		reg = pci_read_config32(ctrl->d0, register_values[i]);
+		reg &= register_values[i + 1];
+		reg |= register_values[i + 2] & ~(register_values[i + 1]);
+		pci_write_config32(ctrl->d0, register_values[i], reg);
+
+		PRINT_DEBUG("    Set register 0x");
+		PRINT_DEBUG_HEX32(register_values[i]);
+		PRINT_DEBUG(" to 0x");
+		PRINT_DEBUG_HEX32(reg);
+		PRINT_DEBUG("\r\n");
+	}
 }
 
+/**
+ * TODO.
+ *
+ * @param Memory controller
+ */
 static void sdram_set_spd_registers(const struct mem_controller *ctrl)
 {
-#define T133 7
-	unsigned char Trp = 1, Tras = 1, casl = 2, val;
-	unsigned char timing = 0xe4;
-	/* read Trp */
-	val = smbus_read_byte(0x50, 27);
-	if (val < 2*T133)
-		Trp = 1;
-	val = smbus_read_byte(0x50, 30);
-	if (val < 5*T133)
-		Tras = 0;
-	val = smbus_read_byte(0x50, 18);
-	if (val < 8)
-		casl = 1;
-	if (val < 4)
-		casl = 0;
-	
-	val = (Trp << 7) | (Tras << 6) | (casl << 4) | 4;
-	
-	print_debug_hex8(val); print_debug(" is the computed timing\n");
-	/* don't set it. Experience shows that this screwy chipset should just
-	 * be run with the most conservative timing.
-	 * pci_write_config8(0, 0x64, val);
-	 */
+	/* TODO: Don't hardcode the values here, get info via SPD. */
+
+	/* TODO: Set DRB0-DRB7. */
+	pci_write_config8(ctrl->d0, DRB0, 0x08);
+	pci_write_config8(ctrl->d0, DRB1, 0x08);
+	pci_write_config8(ctrl->d0, DRB2, 0x08);
+	pci_write_config8(ctrl->d0, DRB3, 0x08);
+	pci_write_config8(ctrl->d0, DRB4, 0x08);
+	pci_write_config8(ctrl->d0, DRB5, 0x08);
+	pci_write_config8(ctrl->d0, DRB6, 0x08);
+	pci_write_config8(ctrl->d0, DRB7, 0x08);
+
+	/* TODO: Set DRAMC. Don't enable refresh for now. */
+	pci_write_config8(ctrl->d0, DRAMC, 0x08);
+
+	/* TODO: Set RPS. */
+	pci_write_config16(ctrl->d0, RPS, 0x0001);
+
+	/* TODO: Set SDRAMC. */
+	// pci_write_config16(ctrl->d0, SDRAMC, 0x0000);
+
+	/* TODO: Set PGPOL. */
+	pci_write_config16(ctrl->d0, PGPOL, 0x0107);
+
+	/* TODO: Set NBXCFG. */
+	// pci_write_config32(ctrl->d0, NBXCFG, 0x0100220c);
+
+	/* TODO: Set PMCR? */
+	// pci_write_config8(ctrl->d0, PMCR, 0x14);
+	// pci_write_config8(ctrl->d0, PMCR, 0x10);
+
+	/* TODO? */
+	// pci_write_config8(ctrl->d0, MLT, 0x40);
+	// pci_write_config8(ctrl->d0, DRAMT, 0x03);
+	// pci_write_config8(ctrl->d0, MBSC, 0x03);
+	// pci_write_config8(ctrl->d0, SCRR, 0x38);
 }
 
-static void set_ma_mapping(device_t north, int slot, int type)
+/**
+ * Enable SDRAM.
+ *
+ * @param Number of controllers
+ * @param Memory controller
+ */
+static void sdram_enable(int controllers, const struct mem_controller *ctrl)
 {
-    unsigned char reg, val;
-    int shift;
-
-    reg = 0x58 + slot/2;
-    if (slot%2 >= 1)
-        shift = 0;
-    else
-        shift = 4;
-
-    val = pci_read_config8(north, reg);
-    val &= ~(0xf << shift);
-    val |= type << shift;
-    pci_write_config8(north, reg, val);
-}
+	int i;
 
+	/* TODO: Use a delay here? Needed? */
+	mdelay(200);
 
-static void sdram_enable(int controllers, const struct mem_controller *ctrl) 
-{
-	unsigned char i;
-	static const uint8_t ramregs[] = {
-		0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x56, 0x57
-	};
-	device_t north = 0;
-	uint32_t size, base, slot, ma;
-	/* begin to initialize*/
-	// I forget why we need this, but we do
-	dimms_write(0xa55a5aa5);
-	
-	/* set NOP*/
-	pci_write_config8(north,0x6C, 0x01);
-	print_debug("NOP\r\n");
-	/* wait 200us*/
-	// You need to do the memory reference. That causes the nop cycle. 
-	dimms_read(0);
-	udelay(400);
-	print_debug("PRECHARGE\r\n");
-	/* set precharge */
-	pci_write_config8(north,0x6C, 0x02);
-	print_debug("DUMMY READS\r\n");
-	/* dummy reads*/
-	dimms_read(0);
-	udelay(200);
-	print_debug("CBR\r\n");
-	/* set CBR*/
-	pci_write_config8(north,0x6C, 0x04);
-	
-	/* do 8 reads and wait >100us between each - from via*/
-	dimms_read(0);
-	udelay(200);
-	dimms_read(0);
-	udelay(200);
-	dimms_read(0);
-	udelay(200);
-	dimms_read(0);
-	udelay(200);
-	dimms_read(0);
-	udelay(200);
-	dimms_read(0);
-	udelay(200);
-	dimms_read(0);
-	udelay(200);
-	dimms_read(0);
-	udelay(200);
-	print_debug("MRS\r\n");
-	/* set MRS*/
-	pci_write_config8(north,0x6c, 0x03);
-#if DIMM_CL2
-	dimms_read(0x150);
-#else // CL=3
-	dimms_read(0x1d0);
-#endif
-	udelay(200);
-	print_debug("NORMAL\r\n");
-	/* set to normal mode */
-	pci_write_config8(north,0x6C, 0x08);
-	
-	dimms_write(0x55aa55aa);
-	dimms_read(0);
-	udelay(200);
-	print_debug("set ref. rate\r\n");
-	// Set the refresh rate. 
-#if DIMM_PC133
-	pci_write_config8(north,0x6A, 0x86);
-#else
-	pci_write_config8(north,0x6A, 0x65);
-#endif
-	print_debug("enable multi-page open\r\n");
-	// enable multi-page open
-	pci_write_config8(north,0x6B, 0x0d);
-	
-	base = 0;
-	for(slot = 0; slot < 4; slot++) {
-		size = spd_module_size(slot);
-		/* side 0 */
-		base += size & 0xffff;
-		pci_write_config8(north, ramregs[2*slot], base);
-		/* side 1 */
-		base += size >> 16;
-		if (base > 0xff)
-			base = 0xff;
-		pci_write_config8(north, ramregs[2*slot + 1], base);
-
-		if (!size)
-			continue;
+	/* TODO: How long should the delays be? Fix later. */
+
+	/* 1. Apply NOP. */
+	PRINT_DEBUG("RAM Enable 1: Apply NOP\r\n");
+	do_ram_command(ctrl, RAM_COMMAND_NOP, 0);
+	mdelay(10);
 
-		/* Calculate the value of MA mapping type register,
-		 * based on size of SDRAM chips. */
-		size = (size & 0xffff) << (3 + 3);
-			/* convert module size to be in Mbits */
-		size /= spd_num_chips(slot);
-		print_debug_hex16(size);
-		print_debug(" is the chip size\r\n");
-		if (size < 64)
-			ma = 0;
-		if (size < 256)
-			ma = 8;
-		else
-			ma = 0xe;
-		print_debug_hex16(ma);
-		print_debug(" is the MA type\r\n");
-		set_ma_mapping(north, slot, ma);
+	/* 2. Precharge all. Wait tRP. */
+	PRINT_DEBUG("RAM Enable 2: Precharge all\r\n");
+	do_ram_command(ctrl, RAM_COMMAND_PRECHARGE, 0);
+	mdelay(10);
+
+	/* 3. Perform 8 refresh cycles. Wait tRC each time. */
+	PRINT_DEBUG("RAM Enable 3: CBR\r\n");
+	for (i = 0; i < 8; i++) {
+		do_ram_command(ctrl, RAM_COMMAND_CBR, 0);
+		mdelay(10);
 	}
-	print_err("vt8601 done\r\n");
+
+	/* 4. Mode register set. Wait two memory cycles. */
+	PRINT_DEBUG("RAM Enable 4: Mode register set\r\n");
+	do_ram_command(ctrl, RAM_COMMAND_MRS, 0x1d0);
+	// TODO: Is 0x1d0 correct?
+	// do_ram_command(ctrl, RAM_COMMAND_MRS, 0x1d0000);
+	mdelay(10);
+	mdelay(10);
+
+	/* 5. Normal operation. */
+	PRINT_DEBUG("RAM Enable 5: Normal operation\r\n");
+	do_ram_command(ctrl, RAM_COMMAND_NORMAL, 0);
+	mdelay(10);
+
+	/* 6. Finally enable refresh. */
+	PRINT_DEBUG("RAM Enable 6: Enable refresh\r\n");
+	// pci_write_config8(ctrl->d0, PMCR, 0x10);
+	spd_enable_refresh(ctrl);
+	mdelay(10);
+
+	PRINT_DEBUG("Northbridge following SDRAM init:\r\n");
+	DUMPNORTH();
 }