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/*
* First stage bootstrap for Power Macintosh.
* Because of space restrictions, the original C code
* has been turned into hand-trimmed assembly
* (with a little bit of help from gcc :-).
*/
#include <layout.h>
.file "first.c"
/*
* Register usage in main:
* 14 high part of address
* 20 bp
* 21 i
* 22 prom_entry
* 25 start
* 26 fp
* 27 bdev
* 28 addr
* 29 bs
*
* Register usage in call_prom:
* 23 nargs
*
*/
.section .rodata
.LC0: .string "finddevice"
.LC1: .string "/chosen"
.LC1a: .string "/options"
.LC2: .string "getprop"
.LC3: .string "bootpath"
.LC3a: .string "boot-device"
.LC4: .string "open"
.LC5: .string "seek"
.LC6: .string "read"
.LC7: .string "exit"
.LC8: .string "enter"
.section ".text"
.align 2
.globl main
.type main,@function
/* main(a1, a2, void (*prom_entry)(struct prom_args *)) */
main:
lis 14,.LC0@ha
/* Make sure our code is consistent in the I and D caches. */
addi 3,14,main@l
li 4,32
mtctr 4
1: dcbf 0,3
icbi 0,3
addi 3,3,0x20
bdnz 1b
sync
isync
/* Use the BAT2 & 3 registers to map the 1st 16MB of RAM to 0. */
mfpvr 9
rlwinm 9,9,16,16,31 /* r9 = 1 for 601, 4 for 604 */
/* the 604 case now works on G3, and should */
/* work on everything else too */
cmpi 0,9,1
bne 4f
li 7,4 /* set up BAT registers for 601 */
li 8,0x7f
b 5f
4: li 7,0x1ff /* set up BAT registers for 604 et al */
li 8,2
mtdbatl 3,8
mtdbatu 3,7
mtibatl 3,8
mtibatu 3,7
b 6f
5: mtibatu 3,7
mtibatl 3,8
oris 7,7,0x80
oris 8,8,0x80
mtibatu 2,7
mtibatl 2,8
6: isync
/* Load up an initial stack pointer */
lis 1,STACK_TOP@h
subi 1,1,0x180
mr 22,5 /* prom = prom_entry */
addi 3,14,.LC0@l /* chosen_handle = call_prom("finddevice, */
li 4,1 /* 1, "/chosen"); */
addi 5,14,.LC1@l
bl call_prom
addi 7,1,8 /* bootpath[0] = 0 */
li 0,0
stw 0,0(7)
mr 5,3
addi 3,14,.LC2@l /* call_prom("getprop", 4, chosen_handle, */
li 4,4 /* "bootpath", bootpath, */
addi 6,14,.LC3@l /* sizeof(bootpath)); */
li 8,256
bl call_prom
lbz 0,8(1) /* if (bootpath[0] == 0) { */
cmpi 0,0,0
bne 11f
addi 3,14,.LC0@l /* options_handle = call_prom("finddevice", */
li 4,1 /* 1, "/options"); */
addi 5,14,.LC1a@l
bl call_prom
mr 5,3 /* call_prom("getprop", 4, options_handle, */
addi 3,14,.LC2@l /* "boot-device", bootpath, */
li 4,4 /* sizeof(bootpath)); */
addi 6,14,.LC3a@l
li 8,256
bl call_prom
11: addi 3,1,7 /* for (s = bootpath; *s != 0; ++s) */
1: lbzu 0,1(3)
cmpwi 0,0,0
beq 2f
cmpwi 0,0,58 /* if (*s == ':') { */
bne 1b
li 0,0 /* *s = 0; break; } */
stb 0,0(3)
2: addi 3,14,.LC4@l /* bdev = call_prom("open", 1, bootpath); */
li 4,1
addi 5,1,8
bl call_prom
mr 27,3
addi 0,27,1 /* if (bdev == 0 || bdev == -1) */
cmplwi 0,0,1
ble out /* goto out; */
addi 26,14,FIRST_INFO@l /* fp = FIRST_INFO; */
lwz 28,16(26) /* addr = fp->second_base; */
mr 25,28 /* start = (void *) addr; */
lwz 29,12(26) /* bs = fp->blocksize; */
addi 20,26,0x38-4 /* bp = &fp->blknos[-1]; */
lwz 21,8(26) /* i = fp->nblocks; do { */
3: addi 3,14,.LC5@l /* call_prom("seek", 3, bdev, */
li 4,3 /* 0, *++bp * 512); */
mr 5,27
lwzu 31,4(20)
srwi 6,31,23
slwi 7,31,9
bl call_prom
mr 16,3
addi 3,14,.LC6@l /* if (call_prom("read", 3, bdev, */
li 4,3 /* addr, bs) != bs) */
mr 5,27
mr 6,28
mr 7,29
bl call_prom
mr 30,3
cmpw 0,3,29 /* goto out; */
bne out
add 28,28,29 /* addr += bs; */
addic. 21,21,-1 /* } while (--i > 0); */
bgt 3b
mr 3,25 /* flush_cache(start, addr); */
4: dcbf 0,3
icbi 0,3
addi 3,3,0x20
cmplw 3,28
blt 4b
sync
isync
#if 0
addi 3,14,.LC8@l /* call_prom("enter", 0); */
li 4,0
bl call_prom
#endif
mtlr 25 /* (*start)(prom_entry, fp); */
mr 3,22
mr 4,26
/*
* Let the second stage know that it's being called from the PowerMac
* first stage bootloader
* -- Cort
*/
lis 5,0xdeadbeef@h
ori 5,5,0xdeadbeef@l
blrl
out:
addi 3,14,.LC8@l /* call_prom("enter", 0); */
li 4,0
bl call_prom
addi 3,14,.LC7@l /* call_prom("exit", 0); */
li 4,0
bl call_prom
b out
.Lfe1:
.size main,.Lfe1-main
.align 2
.globl call_prom
.type call_prom,@function
.long 0x403c
/* call_prom(service, nargs, a0, a1, a2, a3) */
call_prom:
stwu 1,-80(1)
mflr 0
stw 0,84(1)
mr 23,4 /* nargs */
stw 3,8(1) /* args.service = service; */
stw 23,12(1) /* args.nargs = nargs; */
li 0,1 /* args.nret = 1; */
stw 0,16(1)
stw 5,20(1) /* args.params[0] = a0; */
stw 6,24(1) /* args.params[1] = a1; */
mtlr 22
stw 7,28(1) /* args.params[2] = a2; */
stw 8,32(1) /* args.params[3] = a3; */
addi 3,1,8
blrl /* (*prom)(&args); */
slwi 23,23,2 /* return args.params[nargs]; */
add 9,1,23
lwz 3,20(9)
lwz 0,84(1)
mtlr 0
addi 1,1,80
blr
.Lfe2:
.size call_prom,.Lfe2-call_prom
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