/*
* Copyright (C) 1998 Dan Malek <dmalek@jlc.net>
* Copyright (C) 1999 Magnus Damm <kieraypc01.p.y.kie.era.ericsson.se>
* Copyright (C) 2000,2001,2002 Wolfgang Denk <wd@denx.de>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/* U-Boot - Startup Code for PowerPC based Embedded Boards
*
*
* The processor starts at 0x00000100 and the code is executed
* from flash. The code is organized to be at an other address
* in memory, but as long we don't jump around before relocating.
* board_init lies at a quite high address and when the cpu has
* jumped there, everything is ok.
* This works because the cpu gives the FLASH (CS0) the whole
* address space at startup, and board_init lies as a echo of
* the flash somewhere up there in the memorymap.
*
* board_init will change CS0 to be positioned at the correct
* address and (s)dram will be positioned at address 0
*/
#include <config.h>
#include <mpc824x.h>
#include <version.h>
#define _LINUX_CONFIG_H 1 /* avoid reading Linux autoconf.h file */
#include <ppc_asm.tmpl>
#include <ppc_defs.h>
#include <asm/cache.h>
#include <asm/mmu.h>
#ifndef CONFIG_IDENT_STRING
#define CONFIG_IDENT_STRING ""
#endif
/* We don't want the MMU yet.
*/
#undef MSR_KERNEL
/* FP, Machine Check and Recoverable Interr. */
#define MSR_KERNEL ( MSR_FP | MSR_ME | MSR_RI )
/*
* Set up GOT: Global Offset Table
*
* Use r14 to access the GOT
*/
START_GOT
GOT_ENTRY(_GOT2_TABLE_)
GOT_ENTRY(_FIXUP_TABLE_)
GOT_ENTRY(_start)
GOT_ENTRY(_start_of_vectors)
GOT_ENTRY(_end_of_vectors)
GOT_ENTRY(transfer_to_handler)
GOT_ENTRY(__init_end)
GOT_ENTRY(_end)
GOT_ENTRY(__bss_start)
#if defined(CONFIG_FADS)
GOT_ENTRY(environment)
#endif
END_GOT
/*
* r3 - 1st arg to board_init(): IMMP pointer
* r4 - 2nd arg to board_init(): boot flag
*/
.text
.long 0x27051956 /* U-Boot Magic Number */
.globl version_string
version_string:
.ascii U_BOOT_VERSION
.ascii " (", __DATE__, " - ", __TIME__, ")"
.ascii CONFIG_IDENT_STRING, "\0"
. = EXC_OFF_SYS_RESET
.globl _start
_start:
li r21, BOOTFLAG_COLD /* Normal Power-On: Boot from FLASH */
b boot_cold
. = EXC_OFF_SYS_RESET + 0x10
.globl _start_warm
_start_warm:
li r21, BOOTFLAG_WARM /* Software reboot */
b boot_warm
boot_cold:
boot_warm:
/* Initialize machine status; enable machine check interrupt */
/*----------------------------------------------------------------------*/
li r3, MSR_KERNEL /* Set FP, ME, RI flags */
mtmsr r3
mtspr SRR1, r3 /* Make SRR1 match MSR */
addis r0,0,0x0000 /* lets make sure that r0 is really 0 */
mtspr HID0, r0 /* disable I and D caches */
mfspr r3, ICR /* clear Interrupt Cause Register */
mfmsr r3 /* turn off address translation */
addis r4,0,0xffff
ori r4,r4,0xffcf
and r3,r3,r4
mtmsr r3
isync
sync /* the MMU should be off... */
in_flash:
#if defined(CONFIG_BMW)
bl early_init_f /* Must be ASM: no stack yet! */
#endif
/*
* Setup BATs - cannot be done in C since we don't have a stack yet
*/
bl setup_bats
/* Enable MMU.
*/
mfmsr r3
ori r3, r3, (MSR_IR | MSR_DR)
mtmsr r3
#if !defined(CONFIG_BMW)
/* Enable and invalidate data cache.
*/
mfspr r3, HID0
mr r2, r3
ori r3, r3, HID0_DCE | HID0_DCI
ori r2, r2, HID0_DCE
sync
mtspr HID0, r3
mtspr HID0, r2
sync
/* Allocate Initial RAM in data cache.
*/
lis r3, CFG_INIT_RAM_ADDR@h
ori r3, r3, CFG_INIT_RAM_ADDR@l
li r2, 128
mtctr r2
1:
dcbz r0, r3
addi r3, r3, 32
bdnz 1b
/* Lock way0 in data cache.
*/
mfspr r3, 1011
lis r2, 0xffff
ori r2, r2, 0xff1f
and r3, r3, r2
ori r3, r3, 0x0080
sync
mtspr 1011, r3
#endif /* !CONFIG_BMW */
/*
* Thisk the stack pointer *somewhere* sensible. Doesnt
* matter much where as we'll move it when we relocate
*/
lis r1, (CFG_INIT_RAM_ADDR + CFG_GBL_DATA_OFFSET)@h
ori r1, r1, (CFG_INIT_RAM_ADDR + CFG_GBL_DATA_OFFSET)@l
li r0, 0 /* Make room for stack frame header and */
stwu r0, -4(r1) /* clear final stack frame so that */
stwu r0, -4(r1) /* stack backtraces terminate cleanly */
/* let the C-code set up the rest */
/* */
/* Be careful to keep code relocatable ! */
/*----------------------------------------------------------------------*/
GET_GOT /* initialize GOT access */
/* r3: IMMR */
bl cpu_init_f /* run low-level CPU init code (from Flash) */
mr r3, r21
/* r3: BOOTFLAG */
bl board_init_f /* run 1st part of board init code (from Flash) */
.globl _start_of_vectors
_start_of_vectors:
/* Machine check */
STD_EXCEPTION(EXC_OFF_MACH_CHCK, MachineCheck, MachineCheckException)
/* Data Storage exception. "Never" generated on the 860. */
STD_EXCEPTION(EXC_OFF_DATA_STOR, DataStorage, UnknownException)
/* Instruction Storage exception. "Never" generated on the 860. */
STD_EXCEPTION(EXC_OFF_INS_STOR, InstStorage, UnknownException)
/* External Interrupt exception. */
STD_EXCEPTION(EXC_OFF_EXTERNAL, ExtInterrupt, external_interrupt)
/* Alignment exception. */
. = EXC_OFF_ALIGN
Alignment:
EXCEPTION_PROLOG
mfspr r4,DAR
stw r4,_DAR(r21)
mfspr r5,DSISR
stw r5,_DSISR(r21)
addi r3,r1,STACK_FRAME_OVERHEAD
li r20,MSR_KERNEL
rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */
lwz r6,GOT(transfer_to_handler)
mtlr r6
blrl
.L_Alignment:
.long AlignmentException - _start + EXC_OFF_SYS_RESET
.long int_return - _start + EXC_OFF_SYS_RESET
/* Program check exception */
. = EXC_OFF_PROGRAM
ProgramCheck:
EXCEPTION_PROLOG
addi r3,r1,STACK_FRAME_OVERHEAD
li r20,MSR_KERNEL
rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */
lwz r6,GOT(transfer_to_handler)
mtlr r6
blrl
.L_ProgramCheck:
.long ProgramCheckException - _start + EXC_OFF_SYS_RESET
.long int_return - _start + EXC_OFF_SYS_RESET
/* No FPU on MPC8xx. This exception is not supposed to happen.
*/
STD_EXCEPTION(EXC_OFF_FPUNAVAIL, FPUnavailable, UnknownException)
/* I guess we could implement decrementer, and may have
* to someday for timekeeping.
*/
STD_EXCEPTION(EXC_OFF_DECR, Decrementer, timer_interrupt)
STD_EXCEPTION(0xa00, Trap_0a, UnknownException)
STD_EXCEPTION(0xb00, Trap_0b, UnknownException)
. = 0xc00
/*
* r0 - SYSCALL number
* r3-... arguments
*/
SystemCall:
addis r11,r0,0 /* get functions table addr */
ori r11,r11,0 /* Note: this code is patched in trap_init */
addis r12,r0,0 /* get number of functions */
ori r12,r12,0
cmplw 0, r0, r12
bge 1f
rlwinm r0,r0,2,0,31 /* fn_addr = fn_tbl[r0] */
add r11,r11,r0
lwz r11,0(r11)
li r20,0xd00-4 /* Get stack pointer */
lwz r12,0(r20)
subi r12,r12,12 /* Adjust stack pointer */
li r0,0xc00+_end_back-SystemCall
cmplw 0, r0, r12 /* Check stack overflow */
bgt 1f
stw r12,0(r20)
mflr r0
stw r0,0(r12)
mfspr r0,SRR0
stw r0,4(r12)
mfspr r0,SRR1
stw r0,8(r12)
li r12,0xc00+_back-SystemCall
mtlr r12
mtspr SRR0,r11
1: SYNC
rfi
_back:
mfmsr r11 /* Disable interrupts */
li r12,0
ori r12,r12,MSR_EE
andc r11,r11,r12
SYNC /* Some chip revs need this... */
mtmsr r11
SYNC
li r12,0xd00-4 /* restore regs */
lwz r12,0(r12)
lwz r11,0(r12)
mtlr r11
lwz r11,4(r12)
mtspr SRR0,r11
lwz r11,8(r12)
mtspr SRR1,r11
addi r12,r12,12 /* Adjust stack pointer */
li r20,0xd00-4
stw r12,0(r20)
SYNC
rfi
_end_back:
STD_EXCEPTION(EXC_OFF_TRACE, SingleStep, UnknownException)
STD_EXCEPTION(EXC_OFF_FPUNASSIST, Trap_0e, UnknownException)
STD_EXCEPTION(EXC_OFF_PMI, Trap_0f, UnknownException)
STD_EXCEPTION(EXC_OFF_ITME, InstructionTransMiss, UnknownException)
STD_EXCEPTION(EXC_OFF_DLTME, DataLoadTransMiss, UnknownException)
STD_EXCEPTION(EXC_OFF_DSTME, DataStoreTransMiss, UnknownException)
STD_EXCEPTION(EXC_OFF_IABE, InstructionBreakpoint, DebugException)
STD_EXCEPTION(EXC_OFF_SMIE, SysManageInt, UnknownException)
STD_EXCEPTION(0x1500, Reserved5, UnknownException)
STD_EXCEPTION(0x1600, Reserved6, UnknownException)
STD_EXCEPTION(0x1700, Reserved7, UnknownException)
STD_EXCEPTION(0x1800, Reserved8, UnknownException)
STD_EXCEPTION(0x1900, Reserved9, UnknownException)
STD_EXCEPTION(0x1a00, ReservedA, UnknownException)
STD_EXCEPTION(0x1b00, ReservedB, UnknownException)
STD_EXCEPTION(0x1c00, ReservedC, UnknownException)
STD_EXCEPTION(0x1d00, ReservedD, UnknownException)
STD_EXCEPTION(0x1e00, ReservedE, UnknownException)
STD_EXCEPTION(0x1f00, ReservedF, UnknownException)
STD_EXCEPTION(EXC_OFF_RMTE, RunModeTrace, UnknownException)
.globl _end_of_vectors
_end_of_vectors:
. = 0x3000
/*
* This code finishes saving the registers to the exception frame
* and jumps to the appropriate handler for the exception.
* Register r21 is pointer into trap frame, r1 has new stack pointer.
*/
.globl transfer_to_handler
transfer_to_handler:
stw r22,_NIP(r21)
lis r22,MSR_POW@h
andc r23,r23,r22
stw r23,_MSR(r21)
SAVE_GPR(7, r21)
SAVE_4GPRS(8, r21)
SAVE_8GPRS(12, r21)
SAVE_8GPRS(24, r21)
#if 0
andi. r23,r23,MSR_PR
mfspr r23,SPRG3 /* if from user, fix up tss.regs */
beq 2f
addi r24,r1,STACK_FRAME_OVERHEAD
stw r24,PT_REGS(r23)
2: addi r2,r23,-TSS /* set r2 to current */
tovirt(r2,r2,r23)
#endif
mflr r23
andi. r24,r23,0x3f00 /* get vector offset */
stw r24,TRAP(r21)
li r22,0
stw r22,RESULT(r21)
mtspr SPRG2,r22 /* r1 is now kernel sp */
#if 0
addi r24,r2,TASK_STRUCT_SIZE /* check for kernel stack overflow */
cmplw 0,r1,r2
cmplw 1,r1,r24
crand 1,1,4
bgt stack_ovf /* if r2 < r1 < r2+TASK_STRUCT_SIZE */
#endif
lwz r24,0(r23) /* virtual address of handler */
lwz r23,4(r23) /* where to go when done */
mtspr SRR0,r24
ori r20,r20,0x30 /* enable IR, DR */
mtspr SRR1,r20
mtlr r23
SYNC
rfi /* jump to handler, enable MMU */
int_return:
mfmsr r28 /* Disable interrupts */
li r4,0
ori r4,r4,MSR_EE
andc r28,r28,r4
SYNC /* Some chip revs need this... */
mtmsr r28
SYNC
lwz r2,_CTR(r1)
lwz r0,_LINK(r1)
mtctr r2
mtlr r0
lwz r2,_XER(r1)
lwz r0,_CCR(r1)
mtspr XER,r2
mtcrf 0xFF,r0
REST_10GPRS(3, r1)
REST_10GPRS(13, r1)
REST_8GPRS(23, r1)
REST_GPR(31, r1)
lwz r2,_NIP(r1) /* Restore environment */
lwz r0,_MSR(r1)
mtspr SRR0,r2
mtspr SRR1,r0
lwz r0,GPR0(r1)
lwz r2,GPR2(r1)
lwz r1,GPR1(r1)
SYNC
rfi
/* Cache functions.
*/
.globl icache_enable
icache_enable:
mfspr r5,HID0 /* turn on the I cache. */
ori r5,r5,0x8800 /* Instruction cache only! */
addis r6,0,0xFFFF
ori r6,r6,0xF7FF
and r6,r5,r6 /* clear the invalidate bit */
sync
mtspr HID0,r5
mtspr HID0,r6
isync
sync
blr
.globl icache_disable
icache_disable:
mfspr r5,HID0
addis r6,0,0xFFFF
ori r6,r6,0x7FFF
and r5,r5,r6
sync
mtspr HID0,r5
isync
sync
blr
.globl icache_status
icache_status:
mfspr r3, HID0
srwi r3, r3, 15 /* >>15 & 1=> select bit 16 */
andi. r3, r3, 1
blr
.globl dcache_enable
dcache_enable:
mfspr r5,HID0 /* turn on the D cache. */
ori r5,r5,0x4400 /* Data cache only! */
mfspr r4, PVR /* read PVR */
srawi r3, r4, 16 /* shift off the least 16 bits */
cmpi 0, 0, r3, 0xC /* Check for Max pvr */
bne NotMax
ori r5,r5,0x0040 /* setting the DCFA bit, for Max rev 1 errata */
NotMax:
addis r6,0,0xFFFF
ori r6,r6,0xFBFF
and r6,r5,r6 /* clear the invalidate bit */
sync
mtspr HID0,r5
mtspr HID0,r6
isync
sync
blr
.globl dcache_disable
dcache_disable:
mfspr r5,HID0
addis r6,0,0xFFFF
ori r6,r6,0xBFFF
and r5,r5,r6
sync
mtspr HID0,r5
isync
sync
blr
.globl dcache_status
dcache_status:
mfspr r3, HID0
srwi r3, r3, 14 /* >>14 & 1=> select bit 17 */
andi. r3, r3, 1
blr
.globl dc_read
dc_read:
/*TODO : who uses this, what should it do?
*/
blr
.globl get_pvr
get_pvr:
mfspr r3, PVR
blr
/*------------------------------------------------------------------------------*/
/*
* void relocate_code (addr_sp, gd, addr_moni)
*
* This "function" does not return, instead it continues in RAM
* after relocating the monitor code.
*
* r3 = dest
* r4 = src
* r5 = length in bytes
* r6 = cachelinesize
*/
.globl relocate_code
relocate_code:
mr r1, r3 /* Set new stack pointer */
mr r9, r4 /* Save copy of Global Data pointer */
mr r10, r5 /* Save copy of Destination Address */
mr r3, r5 /* Destination Address */
#ifdef CFG_RAMBOOT
lis r4, CFG_SDRAM_BASE@h /* Source Address */
ori r4, r4, CFG_SDRAM_BASE@l
#else
lis r4, CFG_MONITOR_BASE@h /* Source Address */
ori r4, r4, CFG_MONITOR_BASE@l
#endif
lwz r5, GOT(__init_end)
sub r5, r5, r4
li r6, CFG_CACHELINE_SIZE /* Cache Line Size */
/*
* Fix GOT pointer:
*
* New GOT-PTR = (old GOT-PTR - CFG_MONITOR_BASE) + Destination Address
*
* Offset:
*/
sub r15, r10, r4
/* First our own GOT */
add r14, r14, r15
/* the the one used by the C code */
add r30, r30, r15
/*
* Now relocate code
*/
cmplw cr1,r3,r4
addi r0,r5,3
srwi. r0,r0,2
beq cr1,4f /* In place copy is not necessary */
beq 7f /* Protect against 0 count */
mtctr r0
bge cr1,2f
la r8,-4(r4)
la r7,-4(r3)
1: lwzu r0,4(r8)
stwu r0,4(r7)
bdnz 1b
b 4f
2: slwi r0,r0,2
add r8,r4,r0
add r7,r3,r0
3: lwzu r0,-4(r8)
stwu r0,-4(r7)
bdnz 3b
/*
* Now flush the cache: note that we must start from a cache aligned
* address. Otherwise we might miss one cache line.
*/
4: cmpwi r6,0
add r5,r3,r5
beq 7f /* Always flush prefetch queue in any case */
subi r0,r6,1
andc r3,r3,r0
mr r4,r3
5: dcbst 0,r4
add r4,r4,r6
cmplw r4,r5
blt 5b
sync /* Wait for all dcbst to complete on bus */
mr r4,r3
6: icbi 0,r4
add r4,r4,r6
cmplw r4,r5
blt 6b
7: sync /* Wait for all icbi to complete on bus */
isync
/*
* We are done. Do not return, instead branch to second part of board
* initialization, now running from RAM.
*/
addi r0, r10, in_ram - _start + EXC_OFF_SYS_RESET
mtlr r0
blr
in_ram:
/*
* Relocation Function, r14 point to got2+0x8000
*
* Adjust got2 pointers, no need to check for 0, this code
* already puts a few entries in the table.
*/
li r0,__got2_entries@sectoff@l
la r3,GOT(_GOT2_TABLE_)
lwz r11,GOT(_GOT2_TABLE_)
mtctr r0
sub r11,r3,r11
addi r3,r3,-4
1: lwzu r0,4(r3)
add r0,r0,r11
stw r0,0(r3)
bdnz 1b
/*
* Now adjust the fixups and the pointers to the fixups
* in case we need to move ourselves again.
*/
2: li r0,__fixup_entries@sectoff@l
lwz r3,GOT(_FIXUP_TABLE_)
cmpwi r0,0
mtctr r0
addi r3,r3,-4
beq 4f
3: lwzu r4,4(r3)
lwzux r0,r4,r11
add r0,r0,r11
stw r10,0(r3)
stw r0,0(r4)
bdnz 3b
4:
clear_bss:
/*
* Now clear BSS segment
*/
lwz r3,GOT(__bss_start)
lwz r4,GOT(_end)
cmplw 0, r3, r4
beq 6f
li r0, 0
5:
stw r0, 0(r3)
addi r3, r3, 4
cmplw 0, r3, r4
blt 5b
6:
mr r3, r9 /* Global Data pointer */
mr r4, r10 /* Destination Address */
bl board_init_r
/*
* Copy exception vector code to low memory
*
* r3: dest_addr
* r7: source address, r8: end address, r9: target address
*/
.globl trap_init
trap_init:
lwz r7, GOT(_start)
lwz r8, GOT(_end_of_vectors)
li r9, 0x100 /* reset vector always at 0x100 */
cmplw 0, r7, r8
bgelr /* return if r7>=r8 - just in case */
mflr r4 /* save link register */
1:
lwz r0, 0(r7)
stw r0, 0(r9)
addi r7, r7, 4
addi r9, r9, 4
cmplw 0, r7, r8
bne 1b
/*
* relocate `hdlr' and `int_return' entries
*/
li r7, .L_MachineCheck - _start + EXC_OFF_SYS_RESET
li r8, Alignment - _start + EXC_OFF_SYS_RESET
2:
bl trap_reloc
addi r7, r7, 0x100 /* next exception vector */
cmplw 0, r7, r8
blt 2b
li r7, .L_Alignment - _start + EXC_OFF_SYS_RESET
bl trap_reloc
li r7, .L_ProgramCheck - _start + EXC_OFF_SYS_RESET
bl trap_reloc
li r7, .L_FPUnavailable - _start + EXC_OFF_SYS_RESET
li r8, SystemCall - _start + EXC_OFF_SYS_RESET
3:
bl trap_reloc
addi r7, r7, 0x100 /* next exception vector */
cmplw 0, r7, r8
blt 3b
li r7, .L_SingleStep - _start + EXC_OFF_SYS_RESET
li r8, _end_of_vectors - _start + EXC_OFF_SYS_RESET
4:
bl trap_reloc
addi r7, r7, 0x100 /* next exception vector */
cmplw 0, r7, r8
blt 4b
mtlr r4 /* restore link register */
blr
/*
* Function: relocate entries for one exception vector
*/
trap_reloc:
lwz r0, 0(r7) /* hdlr ... */
add r0, r0, r3 /* ... += dest_addr */
stw r0, 0(r7)
lwz r0, 4(r7) /* int_return ... */
add r0, r0, r3 /* ... += dest_addr */
stw r0, 4(r7)
blr
/* Setup the BAT registers.
*/
setup_bats:
lis r4, CFG_IBAT0L@h
ori r4, r4, CFG_IBAT0L@l
lis r3, CFG_IBAT0U@h
ori r3, r3, CFG_IBAT0U@l
mtspr IBAT0L, r4
mtspr IBAT0U, r3
isync
lis r4, CFG_DBAT0L@h
ori r4, r4, CFG_DBAT0L@l
lis r3, CFG_DBAT0U@h
ori r3, r3, CFG_DBAT0U@l
mtspr DBAT0L, r4
mtspr DBAT0U, r3
isync
lis r4, CFG_IBAT1L@h
ori r4, r4, CFG_IBAT1L@l
lis r3, CFG_IBAT1U@h
ori r3, r3, CFG_IBAT1U@l
mtspr IBAT1L, r4
mtspr IBAT1U, r3
isync
lis r4, CFG_DBAT1L@h
ori r4, r4, CFG_DBAT1L@l
lis r3, CFG_DBAT1U@h
ori r3, r3, CFG_DBAT1U@l
mtspr DBAT1L, r4
mtspr DBAT1U, r3
isync
lis r4, CFG_IBAT2L@h
ori r4, r4, CFG_IBAT2L@l
lis r3, CFG_IBAT2U@h
ori r3, r3, CFG_IBAT2U@l
mtspr IBAT2L, r4
mtspr IBAT2U, r3
isync
lis r4, CFG_DBAT2L@h
ori r4, r4, CFG_DBAT2L@l
lis r3, CFG_DBAT2U@h
ori r3, r3, CFG_DBAT2U@l
mtspr DBAT2L, r4
mtspr DBAT2U, r3
isync
lis r4, CFG_IBAT3L@h
ori r4, r4, CFG_IBAT3L@l
lis r3, CFG_IBAT3U@h
ori r3, r3, CFG_IBAT3U@l
mtspr IBAT3L, r4
mtspr IBAT3U, r3
isync
lis r4, CFG_DBAT3L@h
ori r4, r4, CFG_DBAT3L@l
lis r3, CFG_DBAT3U@h
ori r3, r3, CFG_DBAT3U@l
mtspr DBAT3L, r4
mtspr DBAT3U, r3
isync
/* Invalidate TLBs.
* -> for (val = 0; val < 0x20000; val+=0x1000)
* -> tlbie(val);
*/
lis r3, 0
lis r5, 2
1:
tlbie r3
addi r3, r3, 0x1000
cmp 0, 0, r3, r5
blt 1b
blr
