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/* NIOS2 startup code
*
* This is the entry point on reset and when loading the
* executive from a bootloader.
*
* COPYRIGHT (c) 2005-2006 Kolja Waschk rtemsdev/ixo.de
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
.section .entry
.align 3
movhi et, %hiadj(start)
addi et, et, %lo(start)
jmp et
.section .irq
.align 3
movhi et, %hiadj(_exception_vector)
addi et, et, %lo(_exception_vector)
jmp et
.section .text
.align 3
.globl start
.type start,@function
.extern _exception_vector
start:
#------------------------------------------------------
# disable interrupts
wrctl status, zero
wrctl ienable, zero
#------------------------------------------------------
# invalidate instruction cache
mov r2, r0
movhi r3, %hi(__nios2_icache_size)
ori r3, r3, %lo(__nios2_icache_size)
icache_init_loop:
initi r2
addi r2, r2, __nios2_icache_line_size
bltu r2, r3, icache_init_loop
#------------------------------------------------------
# invalidate data cache
mov r2, r0
movhi r3, %hi(__nios2_dcache_size)
ori r3, r3, %lo(__nios2_dcache_size)
dcache_init_loop:
initd 0(r2)
addi r2, r2, __nios2_dcache_line_size
bltu r2, r3, dcache_init_loop
#------------------------------------------------------
# initialize stack pointer
movhi sp, %hiadj(__alt_stack_pointer - 4)
addi sp, sp, %lo(__alt_stack_pointer - 4)
# initialize global pointer
movhi gp, %hiadj(_gp)
addi gp, gp, %lo(_gp)
# initialize exception tmp register
movhi et, %hiadj(_end)
addi et, et, %lo(_end)
#------------------------------------------------------
# TODO: copy data from flash to RAM, if not there already
# For now its save to assume it is there already when we're
# loading code though JTAG into RAM-only system
# at least copy exception code to right place
movhi r2, %hiadj(__ram_exceptions_start)
addi r2, r2, %lo(__ram_exceptions_start)
movhi r3, %hiadj(brto_ev)
addi r3, r3, %lo(brto_ev)
ldw r4, 0(r3)
stw r4, 0(r2)
ldw r4, 4(r3)
stw r4, 4(r2)
ldw r4, 8(r3)
stw r4, 8(r2)
ldw r4, 12(r3)
stw r4, 12(r2)
#------------------------------------------------------
# clear bss
movhi r2, %hiadj(__bss_start)
addi r2, r2, %lo(__bss_start)
movhi r3, %hiadj(__bss_end)
addi r3, r3, %lo(__bss_end)
beq r2, r3, 1f
0:
stw zero, (r2)
addi r2, r2, 4
bltu r2, r3, 0b
1:
#------------------------------------------------------
# jump to (shared) boot_card (never comes back)
mov r4, zero
mov r5, zero
mov r6, zero
call boot_card
# but just in case it does come back, stick here.
_stuck_in_start:
br _stuck_in_start
#------------------------------------------------------
# code to be placed at exception address
brto_ev:
movhi et, %hiadj(_exception_vector)
addi et, et, %lo(_exception_vector)
jmp et
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