grub/grub-core/boot/mips/yeeloong/fwstart.S

/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2000,2001,2002,2003,2004,2005,2007,2008,2009,2010  Free Software Foundation, Inc.
 *
 *  GRUB 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <grub/mips/yeeloong/serial.h>
#include <grub/mips/yeeloong/pci.h>
#include <grub/mips/loongson.h>
#include <grub/pci.h>
#include <grub/machine/serial.h>
#include <grub/ns8250.h>
#include <grub/cs5536.h>
#include <grub/smbus.h>

	.set noreorder
	.set noat
	.set nomacro

	.global start,_start,__start
start:
_start:
__start:	
	bal serial_hw_init
	 nop
	/* Find CS5536 controller.  */
	/* $t4 chooses device in priority encoding.  */
	/* Resulting value is kept in GRUB_MACHINE_PCI_CONF_CTRL_REG.
	   This way we don't need to sacrifice a register for it.  */
	/* We have only one bus (0). Function is 0.  */
	lui $t0, %hi(GRUB_MACHINE_PCI_CONF_CTRL_REG_ADDR)
	lui $t1, %hi(GRUB_MACHINE_PCI_CONFSPACE)
	lui $t3, %hi(GRUB_CS5536_PCIID)
	addiu $t3, $t3, %lo(GRUB_CS5536_PCIID)
	ori $t4, $zero, 1
	lui $a0, %hi(no_cs5536)
1:
	andi $t4, $t4, ((1 << GRUB_PCI_NUM_DEVICES) - 1)
	beql  $t4, $zero, fatal
	 addiu $a0, $a0, %lo(no_cs5536)
	sw   $t4, %lo(GRUB_MACHINE_PCI_CONF_CTRL_REG_ADDR) ($t0)
	lw   $t2, (%lo(GRUB_MACHINE_PCI_CONFSPACE) + GRUB_PCI_REG_PCI_ID) ($t1)
	bnel  $t2, $t3, 1b
	 sll $t4, $t4, 1

	bal message
	 addiu $a0, $a0, %lo(cs5536_found)
	bal printhex
	 move $a0, $t4

	/* Initialise SMBus controller.  */
	/* Set GPIO LBAR.  */
	lui $a0, %hi(GRUB_CS5536_MSR_GPIO_BAR)
	addiu $a0, $a0, %lo(GRUB_CS5536_MSR_GPIO_BAR)
	ori $a1, $zero, GRUB_CS5536_LBAR_GPIO
	/* Set mask to 0xf and enabled bit to 1.  */
	bal wrmsr
	 ori $a2, $zero, ((GRUB_CS5536_LBAR_MASK_MASK \
	                  | GRUB_CS5536_LBAR_ENABLE) >> 32)

	/* Set SMBUS LBAR.  */
	lui $a0, %hi(GRUB_CS5536_MSR_SMB_BAR)
	addiu $a0, $a0, %lo(GRUB_CS5536_MSR_SMB_BAR)
	ori $a1, $zero, GRUB_CS5536_LBAR_SMBUS
	/* Set mask to 0xf and enabled bit to 1.  */
	bal wrmsr
	 ori $a2, $zero, ((GRUB_CS5536_LBAR_MASK_MASK \
	                   | GRUB_CS5536_LBAR_ENABLE) >> 32)

	lui $a0, %hi(smbus_enabled)
	bal message
	  addiu $a0, $a0, %lo(smbus_enabled)

	/* Enable SMBus controller pins.  */
	lui $t0, %hi(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_GPIO)
	ori $t1, $zero, GRUB_GPIO_SMBUS_PINS
	sw  $t1, %lo(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_GPIO + GRUB_GPIO_REG_OUT_EN) ($t0)
	sw  $t1, %lo(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_GPIO + GRUB_GPIO_REG_OUT_AUX1) ($t0)
	sw  $t1, %lo(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_GPIO + GRUB_GPIO_REG_IN_EN) ($t0)
	sw  $t1, %lo(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_GPIO + GRUB_GPIO_REG_IN_AUX1) ($t0)

	lui $t0, %hi(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_SMBUS)

	/* Disable SMB.  */
	sb $zero, %lo(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL2) ($t0)

	/* Disable interrupts.  */
	sb $zero, %lo(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1) ($t0)

	/* Set as master.  */
	sb $zero, %lo(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_ADDR) ($t0)

	/* Launch SMBus controller at slowest speed possible.  */
	ori $t1, $zero, 0xff
	sb $t1, %lo(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL3) ($t0)
	sb $t1, %lo(GRUB_MACHINE_PCI_IO_BASE + GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL2) ($t0)

	/* Yeeloong has only one memory slot.  */
	/* Output first byte on serial for debugging.  */
	ori $a1, $zero, GRUB_SMB_RAM_START_ADDR
	bal read_spd
	 move $a0, $zero
	bal printhex
	 move $a0, $v0

	bal read_spd
	 ori $a0, $zero, GRUB_SMBUS_SPD_MEMORY_TYPE_ADDR
	ori $t0, $zero, GRUB_SMBUS_SPD_MEMORY_TYPE_DDR2
	lui $a0, %hi(unimplemented_memory_type)
	bne $t0, $v0, fatal
	 addiu $a0, $a0, %hi(unimplemented_memory_type)

	/* And here is our goal: DDR2 controller initialisation.  */
        lui	$t0, %hi(GRUB_CPU_LOONGSON_CORECFG)
        ld	$t1, %lo(GRUB_CPU_LOONGSON_CORECFG) ($t0)
	/* Use addiu for sign-extension.  */
	addiu	$t2, $zero, ~(GRUB_CPU_LOONGSON_CORECFG_DISABLE_DDR2_SPACE|GRUB_CPU_LOONGSON_CORECFG_BUFFER_CPU)
	and	$t1, $t1, $t2
	sd	$t1, %lo (GRUB_CPU_LOONGSON_CORECFG) ($t0)

	b continue

	. = start + GRUB_CPU_LOONGSON_FLASH_TLB_REFILL - GRUB_CPU_LOONGSON_FLASH_START
tlb_refill:	
	mfc0 $s1, GRUB_CPU_LOONGSON_COP0_EPC
	mfc0 $s2, GRUB_CPU_LOONGSON_COP0_BADVADDR
	move $s3, $ra
	lui $a0, %hi(epc)
	bal message
	 addiu $a0, $a0, %lo(epc)

	bal printhex
	 move $a0, $s1

	lui $a0, %hi(badvaddr)
	bal message
	 addiu $a0, $a0, %lo(badvaddr)

	bal printhex
	 move $a0, $s2

	lui $a0, %hi(return_msg)
	bal message
	 addiu $a0, $a0, %lo(return_msg)

	bal printhex
	 move $a0, $s3
	
	lui $a0, %hi(newline)
	bal message
	 addiu $a0, $a0, %lo(newline)

	lui $a0, %hi(unhandled_tlb_refill)
	b fatal
	 addiu $a0, $a0, %lo(unhandled_tlb_refill)

	. = start + GRUB_CPU_LOONGSON_FLASH_CACHE_ERROR - GRUB_CPU_LOONGSON_FLASH_START
cache_error:
	lui $a0, %hi(unhandled_cache_error)
	b fatal
	 addiu $a0, $a0, %lo(unhandled_cache_error)

	. = start + GRUB_CPU_LOONGSON_FLASH_OTHER_EXCEPTION - GRUB_CPU_LOONGSON_FLASH_START
other_exception:
	mfc0 $s0, GRUB_CPU_LOONGSON_COP0_CAUSE
	mfc0 $s1, GRUB_CPU_LOONGSON_COP0_EPC
	mfc0 $s2, GRUB_CPU_LOONGSON_COP0_BADVADDR
	lui $a0, %hi(cause)
	bal message
	 addiu $a0, $a0, %lo(cause)

	bal printhex
	 move $a0, $s0

	lui $a0, %hi(epc)
	bal message
	 addiu $a0, $a0, %lo(epc)

	bal printhex
	 move $a0, $s1

	lui $a0, %hi(badvaddr)
	bal message
	 addiu $a0, $a0, %lo(badvaddr)

	bal printhex
	 move $a0, $s2
	
	lui $a0, %hi(newline)
	bal message
	 addiu $a0, $a0, %lo(newline)
	
	lui $a0, %hi(unhandled_exception)
	b fatal
	 addiu $a0, $a0, %lo(unhandled_exception)

	/* Same as similarly named C function but in asm since
	   we need it early.  */
	/* In: none. Out: none. Clobbered: $t0, $t1, $a0.  */
serial_hw_init:
	lui $t0, %hi (GRUB_MACHINE_SERIAL_PORT)

	/* Turn off the interrupt.  */
	sb $zero, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_IER)($t0)

	/* Set DLAB.  */
	ori $t1, $zero, UART_DLAB
	sb  $t1, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_LCR)($t0)

	/* Set the baud rate 115200.  */
	ori $t1, $zero, GRUB_MACHINE_SERIAL_DIVISOR_115200
	sb $t1, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_DLL)($t0) 
	sb $zero, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_DLH)($t0) 

	/* Set the line status.  */
	ori $t1, $zero, (UART_NO_PARITY | UART_8BITS_WORD | UART_1_STOP_BIT)
        sb  $t1, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_LCR)($t0)

	/* Enable the FIFO.  */
	ori $t1, $zero, UART_ENABLE_FIFO_TRIGGER1
	sb $t1, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_FCR)($t0)

	/* Turn on DTR and RTS.  */
	ori $t1, $zero, UART_ENABLE_DTRRTS
	sb  $t1, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_MCR)($t0)

	/* Let message return to original caller.  */
	lui  $a0, %hi(notification_string)
	addiu $a0, $a0, %lo(notification_string)

	/* Print message on serial console.  */
	/* In: $a0 = asciiz message. Out: none. Clobbered: $t0, $t1, $a0.  */
message:
	lui $t0, %hi (GRUB_MACHINE_SERIAL_PORT)
1:
	lb $t1, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_LSR)($t0)
	andi $t1, $t1, UART_EMPTY_TRANSMITTER
	beq $t1, $zero, 1b
	 nop
	lb  $t1, 0($a0)
	sb  $t1, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_TX)($t0)
	bne $t1, $zero, 1b
	 addiu $a0, $a0, 1
	jr  $ra
	 nop
	
	/* Print 32-bit hexadecimal on serial.
           In:	$a0. Out: None. Clobbered: $a0, $t0, $t1, $t2
	*/
printhex:
	lui $t0, %hi  (GRUB_MACHINE_SERIAL_PORT)
	ori $t2, $zero, 8
1:
	lb $t1, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_LSR)($t0)
	andi $t1, $t1, UART_EMPTY_TRANSMITTER
	beq $t1, $zero, 1b
	 nop
	srl  $t1, $a0, 28
	addiu $t1, $t1, -10
	blt  $t1, $zero, 2f
	 sll  $a0, $a0, 4
	addiu $t1, $t1, 'A'-10-'0' 
2:	addiu $t1, $t1, '0'+10
	sb  $t1, (%lo (GRUB_MACHINE_SERIAL_PORT) + UART_TX)($t0)
	addiu $t2, $t2, -1
	bne $t2, $zero, 1b
	 nop
	jr  $ra
	 nop

fatal:
	bal message
	 nop
self:
	b self
	 nop
	
	/* Write CS5536 MSR.
           In:   $a0 address, $a1 lower word, $a2 upper word.
           Out:	 None
           Clobbered:	 $t0
	*/
wrmsr:
	lui $t0, %hi(GRUB_MACHINE_PCI_CONFSPACE)
	sw  $a0, (%lo(GRUB_MACHINE_PCI_CONFSPACE) + GRUB_CS5536_MSR_MAILBOX_ADDR) ($t0)
	sw  $a1, (%lo(GRUB_MACHINE_PCI_CONFSPACE) + GRUB_CS5536_MSR_MAILBOX_DATA0) ($t0)
	jr $ra
	 sw  $a2, (%lo(GRUB_MACHINE_PCI_CONFSPACE) + GRUB_CS5536_MSR_MAILBOX_DATA1) ($t0)

	/* Wait for SMBus data or empty transmitter.  */
	/* In: $a0 = exception handler. Out: none. Clobbered: $t0, $t1  */
smbus_wait:
1:	
	lui $t0, %hi(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_STATUS + GRUB_MACHINE_PCI_IO_BASE)
	lb $t0, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_STATUS + GRUB_MACHINE_PCI_IO_BASE) ($t0)
	andi $t1, $t0, GRUB_CS5536_SMB_REG_STATUS_SDAST
	bne $t1, $zero, return
	 nop
	andi $t1, $t0, (GRUB_CS5536_SMB_REG_STATUS_BER | GRUB_CS5536_SMB_REG_STATUS_NACK)
	beq $t1, $zero, 1b
	 nop
	jr $a0
	 nop
return:
	jr $ra
	 nop
	
	/* Read SPD byte. In: $a0 byte, $a1 device. Out: $v0 read byte (0x100 on failure).
           Clobbered: $t0, $t1, $t2, $t3, $a0. */
read_spd:
	move $t2, $a0
	move $t3, $ra
	lui $a0, %hi(read_spd_fail)
	addiu $a0, $a0, %hi(read_spd_fail)

	/* Send START.  */
	lui $t0, %hi(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE)
	lb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE) ($t0)
	ori $t1, $t1, GRUB_CS5536_SMB_REG_CTRL1_START
	bal smbus_wait
	 sb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE) ($t0)
	
	/* Send device address.  */
	lui $t0, %hi(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_DATA + GRUB_MACHINE_PCI_IO_BASE)
	sll $t1, $a1, 1
	bal smbus_wait
	 sb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_DATA + GRUB_MACHINE_PCI_IO_BASE) ($t0)

	/* Send ACK.  */
	lui $t0, %hi(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE)
	lb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE) ($t0)
	ori $t1, $t1, GRUB_CS5536_SMB_REG_CTRL1_ACK
	sb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE) ($t0)

	/* Send byte address.  */
	lui $t0, %hi(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_DATA + GRUB_MACHINE_PCI_IO_BASE)
	bal smbus_wait
	 sb $t2, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_DATA + GRUB_MACHINE_PCI_IO_BASE) ($t0)

	/* Send START.  */
	lui $t0, %hi(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE)
	lb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE) ($t0)
	ori $t1, $t1, GRUB_CS5536_SMB_REG_CTRL1_START
	bal smbus_wait
	 sb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE) ($t0)

	/* Send device address.  */
	lui $t0, %hi(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_DATA + GRUB_MACHINE_PCI_IO_BASE)
	sll $t1, $a1, 1
	ori $t1, $t1, 1
	bal smbus_wait
	 sb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_DATA + GRUB_MACHINE_PCI_IO_BASE) ($t0)

	/* Send STOP.  */
	lui $t0, %hi(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE)
	lb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE) ($t0)
	ori $t1, $t1, GRUB_CS5536_SMB_REG_CTRL1_STOP
	bal smbus_wait
	 sb $t1, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_CTRL1 + GRUB_MACHINE_PCI_IO_BASE) ($t0)

	lui $t0, %hi(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_DATA + GRUB_MACHINE_PCI_IO_BASE)
	lb $v0, %lo(GRUB_CS5536_LBAR_SMBUS + GRUB_CS5536_SMB_REG_DATA + GRUB_MACHINE_PCI_IO_BASE) ($t0)
	jr $t3
	 andi $v0, $v0, 0xff
read_spd_fail:
	jr $t3
	 ori $v0, $v0, 0x100

notification_string:	.asciz "GRUB "
no_cs5536:	.asciz "No CS5536 found.\n\r"
cs5536_found:	.asciz "CS5536 at "
sm_failed: .asciz "SM transaction failed.\n\r"
unhandled_tlb_refill:	.asciz "Unhandled TLB refill.\n\r"
unhandled_cache_error:	.asciz "Unhandled cache error.\n\r"
unhandled_exception:	.asciz "Unhandled exception.\n\r"
smbus_enabled:	.asciz "SMBus controller enabled.\n\r"
unimplemented_memory_type:	.asciz "non-DDR2 memory isn't supported.\n\r"
no_cas_latency:		.asciz "Couldn't determine CAS latency.\n\r"
cause:	 .asciz "Cause: "
epc:	.asciz "\n\rEPC: "
badvaddr:	.asciz "\n\rBadVaddr: "
newline:	.asciz "\n\r"
return_msg:	  .asciz "\n\rReturn address: "
caches_enabled:	.asciz "Caches enabled\n\r"

	.p2align 3

regdump:
	.quad 0x0100010000000101 /* 0 */
	.quad 0x0100010100000000 /* 2 */
	.quad 0x0101000001000000 /* 3 */
	.quad 0x0100020200010101 /* 4 */
	.quad 0x0a04030603050203 /* 6 */
	.quad 0x0f0e040000010a0b /* 7 */
	.quad 0x0000010200000102 /* 8 */
	.quad 0x0000060c00000000 /* 9 */
	.quad 0x2323233f3f1f0200 /* a */
	.quad 0x5f7f232323232323 /* b */
	.quad 0x002a3c0615000000 /* c */
	.quad 0x002a002a002a002a /* d */
	.quad 0x002a002a002a002a /* e */
	.quad 0x00b40020006d0004 /* f */
	.quad 0x070007ff00000087 /* 10 */
	.quad 0x000000000016101f /* 11 */
	.quad 0x001c000000000000 /* 12 */
	.quad 0x28e1000200c8006b /* 13 */
	.quad 0x0000204200c8002f /* 14 */
	.quad 0x0000000000030d40 /* 15 */
	.quad 0 /* 16 */
	.quad 0 /* 17 */
	.quad 0 /* 18 */
	.quad 0 /* 19 */
	.quad 0 /* 1a */
	.quad 0 /* 1b */
	.quad 0 /* 1c */

	.p2align

write_dumpreg:	
	ld $t2, 0($t6)
	sd $t2, 0($t4)
	addiu $t4, $t4, GRUB_CPU_LOONGSON_DDR2_REG_STEP
	jr $ra
	 addiu $t6, $t6, GRUB_CPU_LOONGSON_DDR2_REG_SIZE

continue:
	lui $t4, %hi(GRUB_CPU_LOONGSON_DDR2_BASE)
	addiu $t4, $t4, %lo(GRUB_CPU_LOONGSON_DDR2_BASE)
	lui $t6, %hi(regdump)

	/* 0 */
	bal write_dumpreg
	 addiu $t6, $t6, %lo(regdump)

	/* 1 */
	ori $a1, $a1, GRUB_SMB_RAM_START_ADDR
	move $t8, $zero
	lui  $t5, 0x0001
	bal read_spd
	 ori $a0, $zero, GRUB_SMBUS_SPD_MEMORY_NUM_BANKS_ADDR
	ori $t7, $zero, 8
	bne $v0, $t7, 1f
	 ori $t5, $t5, 0x0001
	ori $t8, $t8, GRUB_CPU_LOONGSON_DDR2_REG1_HI_8BANKS
1:
	dsll $t8, $t8, 32
	or $t5, $t5, $t8
	sd  $t5, 0 ($t4)
	addiu $t4, $t4, GRUB_CPU_LOONGSON_DDR2_REG_STEP

	/* 2 */
	bal write_dumpreg
	 nop

	/* 3 */
	bal write_dumpreg
	 nop

	/* 4 */
	bal write_dumpreg
	 nop

	/* 5 */
	/* FIXME: figure termination resistance.  */
	ori $t5, $zero, 0x2
	bal read_spd
	 ori $a0, $zero, GRUB_SMBUS_SPD_MEMORY_NUM_ROWS_ADDR
	/* $v0 = 15 - $v0.  */
	xori $v0, $v0, 0xf
	andi $v0, $v0, 0x7
	sll $v0, $v0, 8
	or $t5, $t5, $v0

	/* Find the fastest supported CAS latency.  */
	bal read_spd
	 ori $a0, $zero, GRUB_SMBUS_SPD_MEMORY_CAS_LATENCY_ADDR
	ori $t0, $zero, GRUB_SMBUS_SPD_MEMORY_CAS_LATENCY_MIN_VALUE
	ori $t1, $zero, (1 << GRUB_SMBUS_SPD_MEMORY_CAS_LATENCY_MIN_VALUE)
2:	
	and $t2, $t1, $v0
	bne $t2, $zero, 1f
	 ori $t3, $zero, 8
	lui $a0, %hi(no_cas_latency)
	beq $t0, $t3, fatal
	 addiu $a0, $a0, %lo(no_cas_latency)
	addiu $t0, $t0, 1
	b 2b
	 sll $t1, $t1, 1
1:
	sll $t0, $t0, 16
	or $t5, $t5, $t0
	
	bal read_spd
	 ori $a0, $zero, GRUB_SMBUS_SPD_MEMORY_NUM_COLUMNS_ADDR
	/* $v0 = 15 - ($v0 + 1) = 14 - $v0.  */
	addiu $v0, $v0, 1
	xori $v0, $v0, 0xf
	andi $v0, $v0, 0x7
	sll $v0, 24
	or $t5, $t5, $v0
	sd  $t5, 0 ($t4)

	addiu $t4, $t4, GRUB_CPU_LOONGSON_DDR2_REG_STEP
	
	ori $t7, $zero, 0x16

1:	
	ld $t2, 0($t6)
	sd $t2, 0($t4)
	addiu $t4, $t4, GRUB_CPU_LOONGSON_DDR2_REG_STEP
	addiu $t7, $t7, -1
	bne $t7, $zero, 1b
	 addiu $t6, $t6, GRUB_CPU_LOONGSON_DDR2_REG_SIZE
	
	lui $t4, %hi(GRUB_CPU_LOONGSON_DDR2_BASE)
	ld  $t5, (%lo(GRUB_CPU_LOONGSON_DDR2_BASE) + 0x30) ($t4)
	ori $t0, $zero, 1
	dsll $t0, $t0, 40
	or $t5, $t5, $t0
	sd  $t5, (%lo(GRUB_CPU_LOONGSON_DDR2_BASE) + 0x30) ($t4)

	/* Desactivate DDR2 registers.  */
        lui	$t0, %hi (GRUB_CPU_LOONGSON_CORECFG)
        ld	$t1, %lo (GRUB_CPU_LOONGSON_CORECFG) ($t0)
	ori	$t1, $t1, GRUB_CPU_LOONGSON_CORECFG_DISABLE_DDR2_SPACE
        sd	$t1, %lo (GRUB_CPU_LOONGSON_CORECFG) ($t0)

	/* Enable cache.  */
	mfc0	$t0, GRUB_CPU_LOONGSON_COP0_CACHE_CONFIG
	addiu 	$t1, $zero, ~GRUB_CPU_LOONGSON_CACHE_TYPE_MASK
	and     $t0, $t1, $t1
	/* Set line size to 32 bytes and disabled cache.  */
	ori   	$t0, $t0, (GRUB_CPU_LOONGSON_COP0_CACHE_CONFIG_ILINESIZE \
	                   | GRUB_CPU_LOONGSON_COP0_CACHE_CONFIG_DLINESIZE \
	                   | GRUB_CPU_LOONGSON_CACHE_ACCELERATED)
	mtc0	$t0, GRUB_CPU_LOONGSON_COP0_CACHE_CONFIG

	/* Invalidate all I-cache entries.  */
	srl $t1, $t0, GRUB_CPU_LOONGSON_COP0_CACHE_ISIZE_SHIFT
	andi $t1, $t1, GRUB_CPU_LOONGSON_COP0_CACHE_SIZE_MASK
	ori $t2, $zero, (1 << (GRUB_CPU_LOONGSON_COP0_CACHE_SIZE_OFFSET \
	                       - GRUB_CPU_LOONGSON_CACHE_LINE_SIZE_LOG_BIG \
	                       - GRUB_CPU_LOONGSON_I_CACHE_LOG_WAYS))
	sll $t1, $t2, $t1
	lui $t2, 0x8000

1:	
	cache GRUB_CPU_LOONGSON_COP0_I_INDEX_INVALIDATE, 0($t2)
	addiu $t1, $t1, -1
	bne $t1, $zero, 1b
	 addiu $t2, $t2, (1 << GRUB_CPU_LOONGSON_COP0_I_INDEX_BIT_OFFSET)

	/* Invalidate all D-cache entries.  */
	srl $t1, $t0, GRUB_CPU_LOONGSON_COP0_CACHE_DSIZE_SHIFT
	andi $t1, $t1, GRUB_CPU_LOONGSON_COP0_CACHE_SIZE_MASK
	ori $t2, $zero, (1 << (GRUB_CPU_LOONGSON_COP0_CACHE_SIZE_OFFSET \
	                       - GRUB_CPU_LOONGSON_CACHE_LINE_SIZE_LOG_BIG \
	                       - GRUB_CPU_LOONGSON_D_CACHE_LOG_WAYS))
	sll $t1, $t2, $t1
	lui $t2, 0x8000
	mtc0 $zero, GRUB_CPU_LOONGSON_COP0_CACHE_TAGLO
	mtc0 $zero, GRUB_CPU_LOONGSON_COP0_CACHE_TAGHI
1:
	/* All four ways.  */
	cache GRUB_CPU_LOONGSON_COP0_D_INDEX_TAG_STORE, 0($t2)
	cache GRUB_CPU_LOONGSON_COP0_D_INDEX_TAG_STORE, 1($t2)
	cache GRUB_CPU_LOONGSON_COP0_D_INDEX_TAG_STORE, 2($t2)
	cache GRUB_CPU_LOONGSON_COP0_D_INDEX_TAG_STORE, 3($t2)
	addiu $t1, $t1, -1
	bne $t1, $zero, 1b
	 addiu $t2, $t2, (1 << GRUB_CPU_LOONGSON_COP0_D_INDEX_BIT_OFFSET)

	/* Invalidate all S-cache entries.  */
	ori $t1, $zero, (1 << (GRUB_CPU_LOONGSON_SECONDARY_CACHE_LOG_SIZE \
	                       - GRUB_CPU_LOONGSON_CACHE_LINE_SIZE_LOG_BIG \
	                       - GRUB_CPU_LOONGSON_S_CACHE_LOG_WAYS))
	lui $t2, 0x8000
	mtc0 $zero, GRUB_CPU_LOONGSON_COP0_CACHE_TAGLO
	mtc0 $zero, GRUB_CPU_LOONGSON_COP0_CACHE_TAGHI
1:
	/* All four ways.  */
	cache GRUB_CPU_LOONGSON_COP0_S_INDEX_TAG_STORE, 0($t2)
	cache GRUB_CPU_LOONGSON_COP0_S_INDEX_TAG_STORE, 1($t2)
	cache GRUB_CPU_LOONGSON_COP0_S_INDEX_TAG_STORE, 2($t2)
	cache GRUB_CPU_LOONGSON_COP0_S_INDEX_TAG_STORE, 3($t2)
	addiu $t1, $t1, -1
	bne $t1, $zero, 1b
	 addiu $t2, $t2, (1 << GRUB_CPU_LOONGSON_COP0_D_INDEX_BIT_OFFSET)
	
	/* Finally enable cache.  */
	mfc0	$t0, GRUB_CPU_LOONGSON_COP0_CACHE_CONFIG
	addiu 	$t1, $zero, ~GRUB_CPU_LOONGSON_CACHE_TYPE_MASK
	and     $t0, $t1, $t1
	ori   	$t0, $t0, GRUB_CPU_LOONGSON_CACHE_CACHED
	mtc0	$t0, GRUB_CPU_LOONGSON_COP0_CACHE_CONFIG

	lui $a0, %hi(caches_enabled)
	bal message
	  addiu $a0, $a0, %lo(caches_enabled)

	/* Set ROM delay cycles to 1.  */
	lui $t0, %hi(GRUB_CPU_LOONGSON_LIOCFG)
	lw  $t1, %lo(GRUB_CPU_LOONGSON_LIOCFG) ($t0)
	addiu $t2, $zero, ~(GRUB_CPU_LOONGSON_ROM_DELAY_MASK \
	                    << GRUB_CPU_LOONGSON_ROM_DELAY_OFFSET)
	and $t1, $t1, $t2
	ori $t1, $t1, (1 << GRUB_CPU_LOONGSON_ROM_DELAY_OFFSET)
	sw  $t1, %lo(GRUB_CPU_LOONGSON_LIOCFG) ($t0)
	
	addiu $a0, $zero, -1
	addiu $a1, $zero, -1

	/* Take advantage of cache.  */
	lui $t0, %hi(cached_continue - 0x20000000)
	addiu $t0, $t0, %lo(cached_continue - 0x20000000)
	jr $t0
	 addiu $a2, $zero, -1

cached_continue: