This patch allows the low-level assembler boot-strap to obtain the RAM size without calling the destructive 'sizer' routine. This allows boot-strapping from a U-Boot image loaded in RAM --- cpu/i386/sc520/sc520_asm.S | 95 ++++++++++++++++++++++++++----------------- cpu/i386/start.S | 5 ++ 2 files changed, 62 insertions(+), 38 deletions(-)
diff --git a/cpu/i386/sc520/sc520_asm.S b/cpu/i386/sc520/sc520_asm.S index 135f7b4..c745454 100644 --- a/cpu/i386/sc520/sc520_asm.S +++ b/cpu/i386/sc520/sc520_asm.S @@ -498,47 +498,21 @@ bad_ram:
dram_done:
- /* readback DRCBENDADR and return the number - * of available ram bytes in %eax */ - - movl $DRCBENDADR, %edi /* DRAM ending address register */ - -bank0: movl (%edi), %eax - movl %eax, %ecx - andl $0x00000080, %ecx - jz bank1 - andl $0x0000007f, %eax - shll $22, %eax - movl %eax, %ebx - -bank1: movl (%edi), %eax - movl %eax, %ecx - andl $0x00008000, %ecx - jz bank2 - andl $0x00007f00, %eax - shll $14, %eax - movl %eax, %ebx - -bank2: movl (%edi), %eax - movl %eax, %ecx - andl $0x00800000, %ecx - jz bank3 - andl $0x007f0000, %eax - shll $6, %eax - movl %eax, %ebx +#if CONFIG_SYS_SDRAM_ECC_ENABLE + /* + * We are in the middle of an existing 'call' - Need to store the + * existing return address before making another 'call' + */ + movl %ebp, %ebx
-bank3: movl (%edi), %eax - movl %eax, %ecx - andl $0x80000000, %ecx - jz done - andl $0x7f000000, %eax - shrl $2, %eax - movl %eax, %ebx + /* Get the memory size */ + movl $init_ecc, %ebp + jmpl get_mem_size
-done: - movl %ebx, %eax +init_ecc: + /* Restore the orignal return address */ + movl %ebx, %ebp
-#if CONFIG_SYS_SDRAM_ECC_ENABLE /* A nominal memory test: just a byte at each address line */ movl %eax, %ecx shrl $0x1, %ecx @@ -575,6 +549,51 @@ set_ecc: mov $0x05, %al movb %al, (%edi) #endif + out: + jmp *%ebp + +/* + * Read and decode the sc520 DRCBENDADR MMCR and return the number of + * available ram bytes in %eax + */ +.globl get_mem_size +get_mem_size: + movl $DRCBENDADR, %edi /* DRAM ending address register */ + +bank0: movl (%edi), %eax + movl %eax, %ecx + andl $0x00000080, %ecx + jz bank1 + andl $0x0000007f, %eax + shll $22, %eax + movl %eax, %ebx + +bank1: movl (%edi), %eax + movl %eax, %ecx + andl $0x00008000, %ecx + jz bank2 + andl $0x00007f00, %eax + shll $14, %eax + movl %eax, %ebx + +bank2: movl (%edi), %eax + movl %eax, %ecx + andl $0x00800000, %ecx + jz bank3 + andl $0x007f0000, %eax + shll $6, %eax + movl %eax, %ebx + +bank3: movl (%edi), %eax + movl %eax, %ecx + andl $0x80000000, %ecx + jz done + andl $0x7f000000, %eax + shrl $2, %eax + movl %eax, %ebx + +done: movl %ebx, %eax jmp *%ebp + diff --git a/cpu/i386/start.S b/cpu/i386/start.S index 25d32e6..1980f1a 100644 --- a/cpu/i386/start.S +++ b/cpu/i386/start.S @@ -63,6 +63,11 @@ early_board_init_ret: jmp mem_init mem_init_ret:
+ /* fetch memory size (into %eax) */ + mov $get_mem_size_ret, %ebp + jmp get_mem_size +get_mem_size_ret: + /* Check we have enough memory for stack */ movl $CONFIG_SYS_STACK_SIZE, %ecx cmpl %ecx, %eax