diff options
Diffstat (limited to 'c/src/lib/libbsp/mips/genmongoosev/start/start.S')
| -rw-r--r-- | c/src/lib/libbsp/mips/genmongoosev/start/start.S | 103 |
1 files changed, 88 insertions, 15 deletions
diff --git a/c/src/lib/libbsp/mips/genmongoosev/start/start.S b/c/src/lib/libbsp/mips/genmongoosev/start/start.S index 525232e2c8..609aaac4df 100644 --- a/c/src/lib/libbsp/mips/genmongoosev/start/start.S +++ b/c/src/lib/libbsp/mips/genmongoosev/start/start.S @@ -17,6 +17,15 @@ * they apply. */ + + +#define PMON_UTIL_ROUTINES 0xbfc00200 +#define UTIL_WARMSTART_VECTOR 21*4 +#define UTIL_CPUINIT_VECTOR 22*4 +#define UTIL_CONFIGUART_VECTOR 23*4 +#define UTIL_PUTCHROM_VECTOR 24*4 + + #include <asm.h> #include "regs.S" @@ -37,6 +46,13 @@ # define LA(t,x) la t,x #endif /* __mips_embedded_pic */ + +/* defined by linkcmds, pointing to the start of the relocation target + memory, referenced in this way so we can avoid defining it + multiply */ + + + .text .align 2 @@ -56,30 +72,77 @@ _start: $LF1 = . + 8 bal $LF1 nop + _branch: - move $5, $31 # $5 == where are we - li $6, 0x8800000c # $6 == where we want to be - #la $6,_branch - beq $5, $6, _start_in_ram + move a1, ra /* save return address from the jump above */ + + /* call down into PMON's CpuInit, so we avoid having to + duplicate all that code plus remember to update both copies + when something changes... Note, a1 must be preserved by + CpuInit */ + + li t7,PMON_UTIL_ROUTINES /* get base address of pmon's vector table */ + lw t0,UTIL_CPUINIT_VECTOR(t7) + nop + jal t0 /* init cpu */ + nop + + lw t0,UTIL_CONFIGUART_VECTOR(t7) + nop + jal t0 /* reconfigure UART for console output */ + nop + + lw t0,UTIL_PUTCHROM_VECTOR(t7) + li a0,'b' /* show we booted */ + jal t0 + + + + /* + get the address of the _branch label above as it would appear in + the relocated code + */ + la a2, _branch /* relocation destination */ + + beq a1, a2, _start_in_ram /* skip relocating if we're already there */ nop - # relocate the code from EEPROM to RAM - la $7, _edata + + /* relocate the code from EEPROM to RAM */ + + lw t0,UTIL_PUTCHROM_VECTOR(t7) + li a0,'r' /* show we're starting relocation */ + jal t0 + + la a3, _edata relocate: - lw $8, ($5) # $8 = *EEPROM - addu $5, $5, 4 # EEPROM++ - sw $8, ($6) # *RAM = $8 - addu $6, $6, 4 # RAM++ - bne $6, $7, relocate # copied all the way to edata? + lw t0, (a1) /* load from EEPROM */ + addu a1, 4 + sw t0, (a2) /* store to RAM */ + addu a2, 4 + bne a2, a3, relocate /* copied all the way to edata? */ nop - la $6, _start_in_ram - jr $6 + + lw t0,UTIL_PUTCHROM_VECTOR(t7) + li a0,'R' /* show we relocated */ + jal t0 + nop + + la a2, _start_in_ram + jr a2 nop .end _start + + + + .globl _start_in_ram .ent _start_in_ram _start_in_ram: + lw t0,UTIL_PUTCHROM_VECTOR(t7) + li a0,'S' /* show we're starting in the target address range */ + jal t0 nop #ifdef __mips_embedded_pic @@ -181,13 +244,23 @@ init: .globl _sys_exit .ent _sys_exit _sys_exit: -7: #ifdef GCRT0 jal _mcleanup nop #endif + + /* return non-zero if we want default behavior, else return to pmon */ + bne a0,zero,7f + nop + + li t0,PMON_UTIL_ROUTINES /* base address of PMON's util_routines table */ + lw t0,UTIL_WARMSTART_VECTOR(t0) /* retrieve _warmstart vector at offset 21*4 */ + nop + j t0 /* and jump */ + nop + # break instruction can cope with 0xfffff, but GAS limits the range: - break 1023 +7: break 1023 nop b 7b # but loop back just in-case nop |