u-boot/board/dbau1x00/lowlevel_init.S

/* Memory sub-system initialization code */

#include <config.h>
#include <asm/regdef.h>
#include <asm/au1x00.h>
#include <asm/mipsregs.h>

#define AU1500_SYS_ADDR		0xB1900000
#define sys_endian		0x0038
#define CP0_Config0		$16
#define CPU_SCALE		((CONFIG_SYS_MHZ) / 12) /* CPU clock is a multiple of 12 MHz */
#define MEM_1MS			((CONFIG_SYS_MHZ) * 1000)

	.text
	.set noreorder
	.set mips32

	.globl	lowlevel_init
lowlevel_init:
	/*
	 * Step 1) Establish CPU endian mode.
	 * Db1500-specific:
	 * Switch S1.1 Off(bit7 reads 1) is Little Endian
	 * Switch S1.1 On (bit7 reads 0) is Big Endian
	 */
#ifdef CONFIG_DBAU1550
	li	t0, MEM_STCFG2
	li	t1, 0x00000040
	sw	t1, 0(t0)

	li	t0, MEM_STTIME2
	li	t1, 0x22080a20
	sw	t1, 0(t0)

	li	t0, MEM_STADDR2
	li	t1, 0x10c03f00
	sw	t1, 0(t0)
#else
	li	t0, MEM_STCFG1
	li	t1, 0x00000080
	sw	t1, 0(t0)

	li	t0, MEM_STTIME1
	li	t1, 0x22080a20
	sw	t1, 0(t0)

	li	t0, MEM_STADDR1
	li	t1, 0x10c03f00
	sw	t1, 0(t0)
#endif

	li	t0, DB1XX0_BCSR_ADDR
	lw	t1,8(t0)
	andi	t1,t1,0x80
	beq	zero,t1,big_endian
	nop
little_endian:

	/* Change Au1 core to little endian */
	li	t0, AU1500_SYS_ADDR
	li	t1, 1
	sw	t1, sys_endian(t0)
	mfc0	t2, CP0_CONFIG
	mtc0	t2, CP0_CONFIG
	nop
	nop

	/* Big Endian is default so nothing to do but fall through */

big_endian:

	/*
	 * Step 2) Establish Status Register
	 * (set BEV, clear ERL, clear EXL, clear IE)
	 */
	li	t1, 0x00400000
	mtc0	t1, CP0_STATUS

	/*
	 * Step 3) Establish CP0 Config0
	 * (set OD, set K0=3)
	 */
	li	t1, 0x00080003
	mtc0	t1, CP0_CONFIG

	/*
	 * Step 4) Disable Watchpoint facilities
	 */
	li t1, 0x00000000
	mtc0	t1, CP0_WATCHLO
	mtc0	t1, CP0_IWATCHLO
	/*
	 * Step 5) Disable the performance counters
	 */
	mtc0	zero, CP0_PERFORMANCE
	nop

	/*
	 * Step 6) Establish EJTAG Debug register
	 */
	mtc0	zero, CP0_DEBUG
	nop

	/*
	 * Step 7) Establish Cause
	 * (set IV bit)
	 */
	li	t1, 0x00800000
	mtc0	t1, CP0_CAUSE

	/* Establish Wired (and Random) */
	mtc0	zero, CP0_WIRED
	nop

#ifdef CONFIG_DBAU1550
	/* No workaround if running from ram */
	lui	t0, 0xffc0
	lui	t3, 0xbfc0
	and	t1, ra, t0
	bne	t1, t3, noCacheJump
	nop

	/*** From AMD YAMON ***/
	/*
	 * Step 8) Initialize the caches
	 */
	li		t0, (16*1024)
	li		t1, 32
	li		t2, 0x80000000
	addu	t3, t0, t2
cacheloop:
	cache	0, 0(t2)
	cache	1, 0(t2)
	addu	t2, t1
	bne		t2, t3, cacheloop
	nop

	/* Save return address */
	move		t3, ra

	/* Run from cacheable space now */
	bal		cachehere
	nop
cachehere:
	li		t1, ~0x20000000 /* convert to KSEG0 */
	and		t0, ra, t1
	addi	t0, 5*4			/* 5 insns beyond cachehere */
	jr		t0
	nop

	/* Restore return address */
	move		ra, t3

	/*
	 * Step 9) Initialize the TLB
	 */
	li		t0, 0			# index value
	li		t1, 0x00000000		# entryhi value
	li		t2, 32			# 32 entries

tlbloop:
	/* Probe TLB for matching EntryHi */
	mtc0	t1, CP0_ENTRYHI
	tlbp
	nop

	/* Examine Index[P], 1=no matching entry */
	mfc0	t3, CP0_INDEX
	li	t4, 0x80000000
	and	t3, t4, t3
	addiu	t1, t1, 1		# increment t1 (asid)
	beq	zero, t3, tlbloop
	nop

	/* Initialize the TLB entry */
	mtc0	t0, CP0_INDEX
	mtc0	zero, CP0_ENTRYLO0
	mtc0	zero, CP0_ENTRYLO1
	mtc0	zero, CP0_PAGEMASK
	tlbwi

	/* Do it again */
	addiu	t0, t0, 1
	bne	t0, t2, tlbloop
	nop

#endif /* CONFIG_DBAU1550 */

	/* First setup pll:s to make serial work ok */
	/* We have a 12 MHz crystal */
	li	t0, SYS_CPUPLL
	li	t1, CPU_SCALE  /* CPU clock */
	sw	t1, 0(t0)
	sync
	nop
	nop

	/* wait 1mS for clocks to settle */
	li	t1, MEM_1MS
1:	add	t1, -1
	bne	t1, zero, 1b
	nop
	/* Setup AUX PLL */
	li	t0, SYS_AUXPLL
	li	t1, 0x20 /* 96 MHz */
	sw	t1, 0(t0) /* aux pll */
	sync

#ifdef CONFIG_DBAU1550
	/*  Static memory controller */
	/* RCE0 - can not change while fetching, do so from icache */
	move		t2, ra /* Store return address */
	bal		getAddr
	nop

getAddr:
	move		t1, ra
	move		ra, t2 /* Move return addess back */

	cache	0x14,0(t1)
	cache	0x14,32(t1)
	/*** /From YAMON ***/

noCacheJump:
#endif /* CONFIG_DBAU1550 */

#ifdef CONFIG_DBAU1550
	li	t0, MEM_STTIME0
	li	t1, 0x040181D7
	sw	t1, 0(t0)

	/* RCE0 AMD MirrorBit Flash (?) */
	li	t0, MEM_STCFG0
	li	t1, 0x00000003
	sw	t1, 0(t0)

	li	t0, MEM_STADDR0
	li	t1, 0x11803E00
	sw	t1, 0(t0)
#else /* CONFIG_DBAU1550 */
	li	t0, MEM_STTIME0
	li	t1, 0x040181D7
	sw	t1, 0(t0)

	/* RCE0 AMD 29LV640M MirrorBit Flash */
	li	t0, MEM_STCFG0
	li	t1, 0x00000013
	sw	t1, 0(t0)

	li	t0, MEM_STADDR0
	li	t1, 0x11E03F80
	sw	t1, 0(t0)
#endif /* CONFIG_DBAU1550 */

	/* RCE1 CPLD Board Logic */
	li	t0, MEM_STCFG1
	li	t1, 0x00000080
	sw	t1, 0(t0)

	li	t0, MEM_STTIME1
	li	t1, 0x22080a20
	sw	t1, 0(t0)

	li	t0, MEM_STADDR1
	li	t1, 0x10c03f00
	sw	t1, 0(t0)

#ifdef CONFIG_DBAU1550
	/* RCE2 CPLD Board Logic */
	li	t0, MEM_STCFG2
	li	t1, 0x00000040
	sw	t1, 0(t0)

	li	t0, MEM_STTIME2
	li	t1, 0x22080a20
	sw	t1, 0(t0)

	li	t0, MEM_STADDR2
	li	t1, 0x10c03f00
	sw	t1, 0(t0)
#else
	li	t0, MEM_STCFG2
	li	t1, 0x00000000
	sw	t1, 0(t0)

	li	t0, MEM_STTIME2
	li	t1, 0x00000000
	sw	t1, 0(t0)

	li	t0, MEM_STADDR2
	li	t1, 0x00000000
	sw	t1, 0(t0)
#endif

	/* RCE3 PCMCIA 250ns */
	li	t0, MEM_STCFG3
	li	t1, 0x00000002
	sw	t1, 0(t0)

	li	t0, MEM_STTIME3
	li	t1, 0x280E3E07
	sw	t1, 0(t0)

	li	t0, MEM_STADDR3
	li	t1, 0x10000000
	sw	t1, 0(t0)

	sync

	/* Set peripherals to a known state */
	li	t0, IC0_CFG0CLR
	li	t1, 0xFFFFFFFF
	sw	t1, 0(t0)

	li	t0, IC0_CFG0CLR
	sw	t1, 0(t0)

	li	t0, IC0_CFG1CLR
	sw	t1, 0(t0)

	li	t0, IC0_CFG2CLR
	sw	t1, 0(t0)

	li	t0, IC0_SRCSET
	sw	t1, 0(t0)

	li	t0, IC0_ASSIGNSET
	sw	t1, 0(t0)

	li	t0, IC0_WAKECLR
	sw	t1, 0(t0)

	li	t0, IC0_RISINGCLR
	sw	t1, 0(t0)

	li	t0, IC0_FALLINGCLR
	sw	t1, 0(t0)

	li	t0, IC0_TESTBIT
	li	t1, 0x00000000
	sw	t1, 0(t0)
	sync

	li	t0, IC1_CFG0CLR
	li	t1, 0xFFFFFFFF
	sw	t1, 0(t0)

	li	t0, IC1_CFG0CLR
	sw	t1, 0(t0)

	li	t0, IC1_CFG1CLR
	sw	t1, 0(t0)

	li	t0, IC1_CFG2CLR
	sw	t1, 0(t0)

	li	t0, IC1_SRCSET
	sw	t1, 0(t0)

	li	t0, IC1_ASSIGNSET
	sw	t1, 0(t0)

	li	t0, IC1_WAKECLR
	sw	t1, 0(t0)

	li	t0, IC1_RISINGCLR
	sw	t1, 0(t0)

	li	t0, IC1_FALLINGCLR
	sw	t1, 0(t0)

	li	t0, IC1_TESTBIT
	li	t1, 0x00000000
	sw	t1, 0(t0)
	sync

	li	t0, SYS_FREQCTRL0
	li	t1, 0x00000000
	sw	t1, 0(t0)

	li	t0, SYS_FREQCTRL1
	li	t1, 0x00000000
	sw	t1, 0(t0)

	li	t0, SYS_CLKSRC
	li	t1, 0x00000000
	sw	t1, 0(t0)

	li	t0, SYS_PININPUTEN
	li	t1, 0x00000000
	sw	t1, 0(t0)
	sync

	li	t0, 0xB1100100
	li	t1, 0x00000000
	sw	t1, 0(t0)

	li	t0, 0xB1400100
	li	t1, 0x00000000
	sw	t1, 0(t0)


	li	t0, SYS_WAKEMSK
	li	t1, 0x00000000
	sw	t1, 0(t0)

	li	t0, SYS_WAKESRC
	li	t1, 0x00000000
	sw	t1, 0(t0)

	/* wait 1mS before setup */
	li	t1, MEM_1MS
1:	add	t1, -1
	bne	t1, zero, 1b
	nop

#ifdef CONFIG_DBAU1550
/* SDCS 0,1,2 DDR SDRAM */
	li	t0, MEM_SDMODE0
	li	t1, 0x04276221
	sw	t1, 0(t0)

	li	t0, MEM_SDMODE1
	li	t1, 0x04276221
	sw	t1, 0(t0)

	li	t0, MEM_SDMODE2
	li	t1, 0x04276221
	sw	t1, 0(t0)

	li	t0, MEM_SDADDR0
	li	t1, 0xe21003f0
	sw	t1, 0(t0)

	li	t0, MEM_SDADDR1
	li	t1, 0xe21043f0
	sw	t1, 0(t0)

	li	t0, MEM_SDADDR2
	li	t1, 0xe21083f0
	sw	t1, 0(t0)

	sync

	li	t0, MEM_SDCONFIGA
	li	t1, 0x9030060a /* Program refresh - disabled */
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDCONFIGB
	li	t1, 0x00028000
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDPRECMD /* Precharge all */
	li	t1, 0
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDWRMD0
	li	t1, 0x40000000
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDWRMD1
	li	t1, 0x40000000
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDWRMD2
	li	t1, 0x40000000
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDWRMD0
	li	t1, 0x00000063
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDWRMD1
	li	t1, 0x00000063
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDWRMD2
	li	t1, 0x00000063
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDPRECMD /* Precharge all */
	sw	zero, 0(t0)
	sync

	/* Issue 2 autoref */
	li	t0, MEM_SDAUTOREF
	sw	zero, 0(t0)
	sync

	li	t0, MEM_SDAUTOREF
	sw	zero, 0(t0)
	sync

	/* Enable refresh */
	li	t0, MEM_SDCONFIGA
	li	t1, 0x9830060a /* Program refresh - enabled */
	sw	t1, 0(t0)
	sync

#else /* CONFIG_DBAU1550 */
/* SDCS 0,1 SDRAM */
	li	t0, MEM_SDMODE0
	li	t1, 0x005522AA
	sw	t1, 0(t0)

	li	t0, MEM_SDMODE1
	li	t1, 0x005522AA
	sw	t1, 0(t0)

	li	t0, MEM_SDMODE2
	li	t1, 0x00000000
	sw	t1, 0(t0)

	li	t0, MEM_SDADDR0
	li	t1, 0x001003F8
	sw	t1, 0(t0)


	li	t0, MEM_SDADDR1
	li	t1, 0x001023F8
	sw	t1, 0(t0)

	li	t0, MEM_SDADDR2
	li	t1, 0x00000000
	sw	t1, 0(t0)

	sync

	li	t0, MEM_SDREFCFG
	li	t1, 0x64000C24 /* Disable */
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDPRECMD
	sw	zero, 0(t0)
	sync

	li	t0, MEM_SDAUTOREF
	sw	zero, 0(t0)
	sync
	sw	zero, 0(t0)
	sync

	li	t0, MEM_SDREFCFG
	li	t1, 0x66000C24 /* Enable */
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDWRMD0
	li	t1, 0x00000033
	sw	t1, 0(t0)
	sync

	li	t0, MEM_SDWRMD1
	li	t1, 0x00000033
	sw	t1, 0(t0)
	sync

#endif /* CONFIG_DBAU1550 */
	/* wait 1mS after setup */
	li	t1, MEM_1MS
1:	add	t1, -1
	bne	t1, zero, 1b
	nop

	li	t0, SYS_PINFUNC
	li	t1, 0x00008080
	sw	t1, 0(t0)

	li	t0, SYS_TRIOUTCLR
	li	t1, 0x00001FFF
	sw	t1, 0(t0)

	li	t0, SYS_OUTPUTCLR
	li	t1, 0x00008000
	sw	t1, 0(t0)
	sync

	jr	ra
	nop