rockbox/firmware/crt0.S

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2002 by Linus Nielsen Feltzing
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/
#include "config.h"
#include "cpu.h"

    .section .init.text
    .global    start
start:
#if CONFIG_CPU == TCC730
    /* Platform:     Gmini 120/SP */
    ;; disable all interrupts
     clrsr fe
    clrsr ie
    clrsr te
    ld a14, #0x3F0000

    ld r5, 0xA5
    ldb @[a14 + 6], r5    ; disable watchdog

    ld a11, #(_datacopy)    ; where the data section is in the flash
    ld a8, #(_datastart)    ; destination

    ;; copy data section from flash to ram.
    ld a9, #_datasize
    ld r6, e9
    cmp eq, r6, #0
    brf .data_copy_loop
    cmp eq, r9, #0
    brt .data_copy_end
.data_copy_loop:
    ldc r2, @a11
    ldw @[a8 + 0], r2
    add a11, #0x2
    add a8, #0x2
    sub r9, #0x2
    sbc r6, #0
    cmp ugt, r6, #0
    brt .data_copy_loop
    cmp ugt, r9, #0
    brt .data_copy_loop
.data_copy_end:

    ;; zero out bss
    ld r2, #0
    ld a8, #(_bssstart)    ; destination
    ld a9, #_bsssize
    ld r6, e9

    cmp eq, r6, #0
    brf .bss_init_loop
    cmp eq, r9, #0
    brt .bss_init_end
.bss_init_loop:
    ldw @[a8 + 0], r2
    add a8, #0x2
    sub r9, #0x2
    sbc r6, #0
    cmp ugt, r6, #0
    brt .bss_init_loop
    cmp ugt, r9, #0
    brt .bss_init_loop
.bss_init_end:

    ;; set stack pointer
    ld a15, _stackend

    ;; go!
    jsr _main

    ;; soft reset
    ld a10, #0
    ldc r10, @a10
    jmp a10


    .section .vectors, "ax"
irq_handler:

    push r0, r1
    push r2, r3
    push r4, r5
    push r6, r7
    push a8, a9
    push a10, a11
    push a12, a13
    push a14
    ld a13, #0x3f0000
    ldb r0, @[a13 + 0x26]
    add r0, r0
    ld a10, #_interrupt_vector
    ldw a13, @[a10 + r0]
    jsr a13
    pop a14
    pop a13, a12
    pop a11, a10
    pop a9, a8
    pop r7, r6
    pop r5, r4
    pop r3, r2
    pop r1, r0
    ret_irq

#elif defined(IRIVER_H100)
    /* Platform:     iRiver H120/H140 */
    move.w  #0x2700,%sr

    move.l  #vectors,%d0
    movec.l %d0,%vbr
        
    move.l  #MBAR+1,%d0
    movec.l %d0,%mbar
        
    move.l  #MBAR2+1,%d0
    movec.l %d0,%mbar2

    lea     MBAR,%a0
    lea     MBAR2,%a1
        
    /* 64K DMA-capable SRAM at 0x10000000
       DMA is enabled and has priority in both banks
       All types of accesses are allowed
       (We might want to restrict that to save power) */
    move.l  #0x10000e01,%d0
    movec.l %d0,%rambar1

    /* 32K Non-DMA SRAM at 0x10010000
       All types of accesses are allowed
       (We might want to restrict that to save power) */
    move.l  #0x10010001,%d0
    movec.l %d0,%rambar0

    /* Chip select 0 - Flash ROM */
    moveq.l #0x00,%d0      /* CSAR0 - Base = 0x00000000 */
    move.l  %d0,(0x080,%a0)
    move.l  #0x001f0101,%d0 /* CSMR0 - 2M, All access, write protect */
    move.l  %d0,(0x084,%a0)
    move.l  #0x00000d80,%d0 /* CSCR0 - 3 wait states, 16 bits, no bursts */
    move.l  %d0,(0x088,%a0)
        
    /* Chip select 1 - LCD controller */
    move.l  #0xf0000000,%d0 /* CSAR1 - Base = 0xf0000000 */
    move.l  %d0,(0x08c,%a0)
    moveq.l #0x75,%d0      /* CSMR1 - 64K, Only data access */
    move.l  %d0,(0x090,%a0)
    move.l  #0x00000180,%d0 /* CSCR1 - 0 wait states, 16 bits, no bursts */
    move.l  %d0,(0x094,%a0)
        
    /* Chip select 2 - ATA controller */
    move.l  #0x20000000,%d0 /* CSAR2 - Base = 0x20000000 */
    move.l  %d0,(0x098,%a0)
    move.l  #0x000f0001,%d0 /* CSMR2 - 64K, Only data access */
    move.l  %d0,(0x09c,%a0)
    move.l  #0x00000080,%d0 /* CSCR2 - no wait states, 16 bits, no bursts */
    move.l  %d0,(0x0a0,%a0) /* NOTE:  I'm not sure about the wait states.
                               We have to be careful with the access times,
                               since IORDY isn't connected to the HDD. */
        

#ifdef BOOTLOADER
    /* The cookie is not reset. This must mean that the boot loader
       has crashed. Let's start the original firmware immediately. */
    lea     0x10017ffc,%a2
    move.l  (%a2),%d0
    move.l  #0xc0015a17,%d1
    cmp.l   %d0,%d1
    bne     .nocookie
    /* Clear the cookie again */
    clr.l   (%a2)
    jmp     8
        
.nocookie:
    /* Set the cookie */
    move.l  %d1,(%a2)
        
    /* Set up the DRAM controller. The refresh is based on the 11.2896MHz
       clock (5.6448MHz bus frequency). We haven't yet started the PLL */
    move.w  #0x8001,%d0
    move.w  %d0,(0x100,%a0) /* DCR - Synchronous, 32 cycle refresh */

    /* Note: we place the SDRAM on an 0x1000000 (16M) offset because
       the 5249 BGA chip has a fault which disables the use of A24. The
       suggested workaround by FreeScale is to offset the base address by
       half the DRAM size and increase the mask to the double.
       In our case this means that we set the base address 16M ahead and
       use a 64M mask.
    */
    move.l  #0x31002520,%d0
    move.l  %d0,(0x108,%a0) /* DACR0 - Base 0x31000000, Banks on 23 and up,
                               CAS latency 1, No refresh yet */
    move.l  #0x03fc0001,%d0 /* Size: 64M because of workaround above */
    move.l  %d0,(0x10c,%a0) /* DMR0 - 32Mb */

    /* Precharge */
    move.l  #0x31002528,%d0
    move.l  %d0,(0x108,%a0) /* DACR0[IP] = 1, next access will issue a
                               Precharge command */
    move.l  #0xabcd1234,%d0
    move.l  %d0,0x31000000  /* Issue precharge command */

    /* Let it refresh */
    move.l  #1000,%d0
.delayloop:
    subq.l  #1,%d0
    bne     .delayloop
        
    /* Refresh */
    move.l  #0x3100a520,%d0
    move.l  %d0,(0x108,%a0) /* Enable refresh */

    /* Mode Register init */
    move.l  #0x3100a560,%d0 /* DACR0[IMRS] = 1, next access will set the
                               Mode Register */
    move.l  %d0,(0x108,%a0)

    move.l  #0xabcd1234,%d0
    move.l  %d0,0x31000800  /* A12=1 means CASL=1 (a0 is not connected) */

    move.l  #0x3100a520,%d0 /* Back to normal, the DRAM is now ready */
    move.l  %d0,(0x108,%a0)
#endif

    /* Invalicate cache */
    move.l  #0x01000000,%d0
    movec.l %d0,%cacr
        
    /* Enable cache, default=non-cacheable,no buffered writes */
    move.l  #0x80000000,%d0
    movec.l %d0,%cacr

    /* Cache enabled in SDRAM only, buffered writes enabled */
    move.l  #0x3103c020,%d0
    movec.l %d0,%acr0
    moveq.l #0,%d0
    movec.l %d0,%acr1

#ifndef BOOTLOADER
    lea     _iramcopy,%a2
    lea     _iramstart,%a3
    lea     _iramend,%a4
.iramloop:
    cmp.l   %a3,%a4
    beq     .iramloopend
    move.w  (%a2)+,(%a3)+
    bra     .iramloop
.iramloopend:
#endif

    lea     _edata,%a2
    lea     _end,%a4
    clr.l   %d0
.edataloop:
    cmp.l   %a2,%a4
    beq     .edataloopend
    move.w  %d0,(%a2)+
    bra    .edataloop
.edataloopend:

    lea     _datacopy,%a2
    lea     _datastart,%a3
    lea     _dataend,%a4
.dataloop:
    cmp.l   %a3,%a4
    beq     .dataloopend
    move.w  (%a2)+,(%a3)+
    bra     .dataloop
.dataloopend:

    /* Munge the main stack */
    lea     stackbegin,%a2
    lea     stackend,%a4
    move.l  #0xdeadbeef,%d0
.mungeloop:
    cmp.l   %a2,%a4
    beq     .mungeloopend
    move.l  %d0,(%a2)+
    bra     .mungeloop
.mungeloopend:

    lea     stackend,%sp
    jsr     main
.hoo:
    bra     .hoo

    .section .resetvectors
vectors:
    .long   stackend
    .long   start
#elif defined(IRIVER_H300)
    /* Platform:     iRiver H320/H340 */

    /* Fill in code here */
#else
    /* Platform:     Archos Jukebox
     * We begin with some tricks. If we have built our code to be loaded
     * via the standalone GDB stub, we will have out VBR at some other
     * location than 0x9000000. We must copy the trap vectors for the
     * GDB stub to our vector table.
     * If, on the other hand, we are running standalone we will have
     * the VBR at 0x9000000, and the copy will not do any harm.
     */
    mov.l   vbr_k,r1
    mov.l   orig_vbr_k,r2

    /* Move the invalid instruction vector (4) */
    mov     #4,r0
    shll2   r0
    mov.l   @(r0,r2),r3
    mov.l   r3,@(r0,r1)

    /* Move the invalid slot vector (6) */
    mov     #6,r0
    shll2   r0
    mov.l   @(r0,r2),r3
    mov.l   r3,@(r0,r1)

    /* Move the bus error vector (9) */
    mov     #9,r0
    shll2   r0
    mov.l   @(r0,r2),r3
    mov.l   r3,@(r0,r1)

    /* Move the DMA bus error vector (10) */
    mov     #10,r0
    shll2   r0
    mov.l   @(r0,r2),r3
    mov.l   r3,@(r0,r1)

    /* Move the NMI vector as well (11) */
    mov     #11,r0
    shll2   r0
    mov.l   @(r0,r2),r3
    mov.l   r3,@(r0,r1)

    /* Move the breakpoint trap vector (32) */
    mov     #32,r0
    shll2   r0
    mov.l   @(r0,r2),r3
    mov.l   r3,@(r0,r1)

    /* Move the IO trap vector (33) */
    mov     #33,r0
    shll2   r0
    mov.l   @(r0,r2),r3
    mov.l   r3,@(r0,r1)

    /* Move the serial Rx interrupt vector (105) */
    mov     #105,r0
    shll2   r0
    mov.l   @(r0,r2),r3
    mov.l   r3,@(r0,r1)

    /* Move the single step trap vector (127) */
    mov     #127,r0
    shll2   r0
    mov.l   @(r0,r2),r3
    mov.l   r3,@(r0,r1)

    ldc     r1,vbr

    /* Now let's get on with the normal business */
    mov.l   stack_k,r15

    /* zero out bss */
    mov.l   edata_k,r0
    mov.l   end_k,r1
    mov     #0,r2
start_l:
    mov.l   r2,@r0
    add     #4,r0
    cmp/ge  r1,r0
    bf      start_l
    nop

    /* copy the .iram section */
    mov.l   iramcopy_k,r0
    mov.l   iram_k,r1
    mov.l   iramend_k,r2
copy_l:
    mov.l   @r0,r3
    mov.l   r3,@r1
    add     #4,r0
    add     #4,r1
    cmp/ge  r2,r1
    bf      copy_l
    nop

    /* copy the .data section, for rombased execution */
    mov.l   datacopy_k,r0
    mov.l   data_k,r1
    mov.l   dataend_k,r2
    /* Don't copy if src and dest are equal */
    cmp/eq  r0,r1
    bt      nodatacopy
copy_l2:
    mov.l   @r0,r3
    mov.l   r3,@r1
    add     #4,r0
    add     #4,r1
    cmp/ge  r2,r1
    bf      copy_l2
    nop
nodatacopy:
    /* Munge the main thread stack */
    mov.l   stack_k,r2
    mov.l   deadbeef_k,r0
    mov.l   stackbegin_k,r1
munge_loop:
    mov.l   r0,@r1
    add     #4,r1
    cmp/ge  r2,r1
    bf      munge_loop
    nop

    mov     #0,r0
    ldc     r0,gbr

    ! call the mainline
    mov.l   main_k,r0
    jsr     @r0
    nop
.hoo:
    bra     .hoo

    .align  2
stack_k:
    .long   _stackend
stackbegin_k:
    .long   _stackbegin
deadbeef_k:
    .long   0xdeadbeef
edata_k:
    .long   _edata
end_k:
    .long   _end
iramcopy_k:
    .long   _iramcopy
iram_k:
    .long   _iramstart
iramend_k:
    .long   _iramend
datacopy_k:
    .long   _datacopy
data_k:
    .long   _datastart
dataend_k:
    .long   _dataend
main_k:
    .long   _main
vbr_k:
    .long   vectors
orig_vbr_k:
    .long   0x9000000

    .section .resetvectors
vectors:
    .long   start
    .long   _stackend
    .long   start
    .long   _stackend
#endif