starto.s

国产CPU－龙芯（loongson)BIOS源代码

/*
 * Common functions are defined below
 */

/*
 * flash_gpio entry 
 */

LEAF(__flash_gpio)
        li      t1, 0xb4013802
        li      t0, 0x550
        sh      t0, (t1)
        subu    t1, t1, 2
        move    t0, a0
        sll     t0, 2
        sb      t0, (t1)
        MK_LAT(GPIO_LOOP)
        j       ra
END(__flash_gpio)


/*
 * led display
 */
LEAF(__led_display)
        li              t0, 0xb80000f0
        sb              a0, (t0)
        li              t0,     2000
9:      subu    t0, 1
        bne             t0, 0, 9b
        nop
        j               ra
END(__led_display)

/*
 *  Clear the TLB. Normally called from start.S.
 */
LEAF(CPU_TLBClear)
	li	a3, 0			# First TLB index.

	li	a2, PG_SIZE_4K
	mtc0   a2, COP_0_TLB_PG_MASK   # Whatever...

1:
	mtc0   zero, COP_0_TLB_HI	# Clear entry high.
	mtc0   zero, COP_0_TLB_LO0	# Clear entry low0.
	mtc0   zero, COP_0_TLB_LO1	# Clear entry low1.

	mtc0    a3, COP_0_TLB_INDEX	# Set the index.
	addiu	a3, 1
	li	a2, 64
	nop
	nop
	tlbwi				# Write the TLB

	bne	a3, a2, 1b
	nop

	jr	ra
	nop
END(CPU_TLBClear)

/*
 *  Set up the TLB. Normally called from start.S.
 */
LEAF(CPU_TLBInit)
	li	a3, 0			# First TLB index.

	li	a2, PG_SIZE_16M
	mtc0   a2, COP_0_TLB_PG_MASK   # All pages are 16Mb.

1:
	and	a2, a0, PG_SVPN
	mtc0   a2, COP_0_TLB_HI	# Set up entry high.

	move	a2, a0
	srl	a2, a0, PG_SHIFT 
	and	a2, a2, PG_FRAME
	ori	a2, PG_IOPAGE
	mtc0   a2, COP_0_TLB_LO0	# Set up entry low0.
	addu	a2, (0x01000000 >> PG_SHIFT)
	mtc0   a2, COP_0_TLB_LO1	# Set up entry low1.

	mtc0    a3, COP_0_TLB_INDEX	# Set the index.
	addiu	a3, 1
	li	a2, 0x02000000
	subu	a1, a2
	nop
	tlbwi				# Write the TLB

	bgtz	a1, 1b
	addu	a0, a2			# Step address 32Mb.

	jr	ra
	nop
END(CPU_TLBInit)



/*
 * Simple character printing routine used before full initialization
 */

LEAF(stringserial)
	move	a2, ra
	addu	a1, a0, s0
	lbu	a0, 0(a1)
1:
	beqz	a0, 2f
	nop
	bal	tgt_putchar
	addiu	a1, 1
	b	1b
	lbu	a0, 0(a1)

2:
	j	a2
	nop
END(stringserial)

LEAF(hexserial)
	move	a2, ra
	move	a1, a0
	li	a3, 7
1:
	rol	a0, a1, 4
	move	a1, a0
	and	a0, 0xf
	la	v0, hexchar
	addu	v0, s0
	addu	v0, a0
	bal	tgt_putchar
	lbu	a0, 0(v0)

	bnez	a3, 1b
	addu	a3, -1

	j	a2
	nop
END(hexserial)

LEAF(tgt_putchar)
	la	v0, IT8172_PCI_IO_BASE + IT_UART_BASE
	addu	v0, UNCACHED_MEMORY_ADDR
1:
	lbu	v1, NSREG(NS16550_LSR)(v0)
	and	v1, LSR_TXRDY
	beqz	v1, 1b
	nop

	sb	a0, NSREG(NS16550_DATA)(v0)

	j	ra
	nop	
END(tgt_putchar)

/* baud rate definitions, matching include/termios.h */
#define B0      0
#define B50     50      
#define B75     75
#define B110    110
#define B134    134
#define B150    150
#define B200    200
#define B300    300
#define B600    600
#define B1200   1200
#define B1800   1800
#define B2400   2400
#define B4800   4800
#define B9600   9600
#define B19200  19200
#define B38400  38400
#define B57600  57600
#define B115200 115200


LEAF(initserial)
	li	v0, KSEG1
	addu	v0, IT8172_PCI_IO_BASE
	addu	v0, IT_PM_DSR
	lh	v1, (v0)
	and	v1, ~0x0100
	sh	v1, (v0)

	la	v0, IT8172_PCI_IO_BASE + IT_UART_BASE
	addu	v0, UNCACHED_MEMORY_ADDR
1:
	li	v1, FIFO_ENABLE|FIFO_RCV_RST|FIFO_XMT_RST|FIFO_TRIGGER_4
	sb	v1, NSREG(NS16550_FIFO)(v0)
	li	v1, CFCR_DLAB
	sb	v1, NSREG(NS16550_CFCR)(v0)
 	li	v1, NS16550HZ/(16*CONS_BAUD)
	sb	v1, NSREG(NS16550_DATA)(v0)
	srl	v1, 8
	sb	v1, NSREG(NS16550_IER)(v0)
	li	v1, CFCR_8BITS
	sb	v1, NSREG(NS16550_CFCR)(v0)
	sb	v1, NSREG(NS16550_MCR)(v0)
	li	v1, 0x0
	sb	v1, NSREG(NS16550_IER)(v0)
	j	ra
	nop
END(initserial)

__main:
	j	ra
	nop


	.rdata
transmit_pat_msg:
	.asciz	"\r\nInvalid transmit pattern.  Must be DDDD or DDxDDx\r\n"
v200_msg:
	.asciz	"\r\nPANIC! Unexpected TLB refill exception!\r\n"
v280_msg:
	.asciz	"\r\nPANIC! Unexpected XTLB refill exception!\r\n"
v380_msg:
	.asciz	"\r\nPANIC! Unexpected General exception!\r\n"
v400_msg:
	.asciz	"\r\nPANIC! Unexpected Interrupt exception!\r\n"
hexchar:
	.ascii	"0123456789abcdef"

	.text
	.align	2


#define I2C_INT_ENABLE	0x80
#define I2C_ENABLE	0x40
#define I2C_ACK		0x04
#define I2C_INT_FLAG	0x08
#define I2C_STOP_BIT	0x10
#define I2C_START_BIT	0x20

#define	I2C_AMOD_RD	0x01

#define	BUS_ERROR				0x00
#define	START_CONDITION_TRA			0x08
#define	RSTART_CONDITION_TRA			0x10
#define	ADDR_AND_WRITE_BIT_TRA_ACK_REC		0x18
#define	ADDR_AND_READ_BIT_TRA_ACK_REC		0x40
#define	SLAVE_REC_WRITE_DATA_ACK_TRA		0x28
#define	MAS_REC_READ_DATA_ACK_NOT_TRA		0x58

#define Index_Invalidate_I      0x00
#define Index_Writeback_Inv_D   0x01
#define Index_Invalidate_SI     0x02
#define Index_Writeback_Inv_SD  0x03
#define Index_Load_Tag_I	0x04
#define Index_Load_Tag_D	0x05
#define Index_Load_Tag_SI	0x06
#define Index_Load_Tag_SD	0x07
#define Index_Store_Tag_I	0x08
#define Index_Store_Tag_D	0x09
#define Index_Store_Tag_SI	0x0A
#define Index_Store_Tag_SD	0x0B
#define Create_Dirty_Excl_D	0x0d
#define Create_Dirty_Excl_SD	0x0f
#define Hit_Invalidate_I	0x10
#define Hit_Invalidate_D	0x11
#define Hit_Invalidate_SI	0x12
#define Hit_Invalidate_SD	0x13
#define Fill			0x14
#define Hit_Writeback_Inv_D	0x15
					/* 0x16 is unused */
#define Hit_Writeback_Inv_SD	0x17
#define Hit_Writeback_I		0x18
#define Hit_Writeback_D		0x19
					/* 0x1a is unused */
#define Hit_Writeback_SD	0x1b
					/* 0x1c is unused */
					/* 0x1e is unused */
#define Hit_Set_Virtual_SI	0x1e
#define Hit_Set_Virtual_SD	0x1f

#define CP0_CONFIG $16
#define CP0_TAGLO  $28
#define CP0_TAGHI  $29

LEAF(godson2_cache_init)
	.set mips3
cache_detect_2way:
	mfc0	t4, CP0_CONFIG
	andi	t5, t4, 0x0e00
	srl	t5, t5, 9
	andi	t6, t4, 0x01c0
	srl	t6, t6, 6
	addiu	t6, t6, 11
	addiu	t5, t5, 11
	addiu	t4, $0, 1
	sllv	t6, t4, t6

#ifdef CONFIG_CACHE_64K_4WAY
	sll	t6,2
#endif

	sllv	t5, t4, t5

#ifdef CONFIG_CACHE_64K_4WAY
	sll	t5,2
#endif
	addiu	t7, $0, 2
####part 3####
	lui	a0, 0x8000
	addu	a1, $0, t5
	addu	a2, $0, t6
cache_init_d2way:
#a0=0x80000000, a1=icache_size, a2=dcache_size
#a3, v0 and v1 used as local registers
	mtc0	$0, CP0_TAGHI
	addu	v0, $0, a0
	addu	v1, a0, a2
1:	slt	a3, v0, v1
	beq	a3, $0, 1f
	nop
	mtc0	$0, CP0_TAGLO
	cache	Index_Store_Tag_D, 0x0(v0)
	mtc0	$0, CP0_TAGLO
	cache	Index_Store_Tag_D, 0x1(v0)
/*#ifdef CONFIG_CACHE_64K_4WAY*/
	mtc0	$0, CP0_TAGLO
	cache   Index_Store_Tag_D, 0x2(v0)

	mtc0	$0, CP0_TAGLO
	cache   Index_Store_Tag_D, 0x3(v0)
/*#endif*/
	beq	$0, $0, 1b
	addiu	v0, v0, 0x20
1:
cache_flush_i2way:
	addu	v0, $0, a0
	addu	v1, a0, a1
1:	slt	a3, v0, v1
	beq	a3, $0, 1f
	nop
	cache	Index_Invalidate_I, 0x0(v0)
#	cache	Index_Invalidate_I, 0x1(v0)
/*#ifdef  CONFIG_CACHE_64K_4WAY*/
#	cache	Index_Invalidate_I, 0x2(v0)
#	cache	Index_Invalidate_I, 0x3(v0)
/*#endif*/
	beq	$0, $0, 1b
	addiu	v0, v0, 0x20
1:
cache_flush_d2way:
	addu	v0, $0, a0
	addu	v1, a0, a2
1:	slt	a3, v0, v1
	beq	a3, $0, 1f
	nop
	cache	Index_Writeback_Inv_D, 0x0(v0)
	cache	Index_Writeback_Inv_D, 0x1(v0)

/*#ifdef CONFIG_CACHE_64K_4WAY*/
	cache	Index_Writeback_Inv_D, 0x2(v0)
	cache	Index_Writeback_Inv_D, 0x3(v0)
/*#endif*/
	beq	$0, $0, 1b
	addiu	v0, v0, 0x20
1:
cache_init_finish:
	nop
	jr	ra
	nop

cache_init_panic:
	TTYDBG("cache init panic\r\n");
1:	b	1b
	nop
	.set mips0
	.end	godson2_cache_init

LEAF(invalidate_external_cache_page)
	.set push
	.set mips3
	li	t0, 0x90000010
	dsll32	t0, t0, 0
	dsubu	t0, t0, 8
	sd	a0, 0(t0)
	jr	ra
	nop	
	.set mips0
	.set pop
	.end invalidate_external_cache_page	

LEAF(init_regs)
/* all initial registers to zero */
	.set push
	.set mips3
	#.set noat
	.set noreorder
	mfc0    t0, COP_0_PRID
	mfc0    v0, COP_0_STATUS_REG 
	mtc0    zero, COP_0_WATCH_LO
	mtc0    zero, COP_0_WATCH_HI

	.set reorder
	and             v0, SR_SOFT_RESET
	or              v0, SR_BOOT_EXC_VEC

	.set noreorder
	mtc0    v0, COP_0_STATUS_REG
	mtc0    zero, COP_0_CAUSE_REG

	jr	ra
	nop
	.set pop
END(init_regs)

LEAF(nullfunction)
	jr ra
	nop
END(nullfunction)

LEAF(PC_REG)
	TTYDBG("PC=")
	move t1, a0
	move a0, ra
	bal hexserial
	nop 
	TTYDBG("\n")
	move a0, t1
	jr ra
	nop
END(PC_REG)