asm_init.s

AT91RM9200的完整启动代码：包括loader, boot及U-boot三部分均已编译通过！欢迎下载使用！

    b       row11x4or12x4
row13x4:
    ori     r20, r20, 0x0a
    b       row11x4or12x4
row11x2:
    ori     r20, r20, 0x0f
row11x4or12x4:
    /* get the size of bank 0-1 */

    li      r3, 0x001f          /* get bank size from spd for bank0/1 */
    bl      spdRead

    rlwinm  r16, r3, 2, 24, 29  /* calculate size in MByte (128 MB max.) */

    li      r3, 0x0005          /* get number of banks from spd for bank0/1 */
    bl      spdRead

    cmpi    0, 0, r3, 2         /* 2 banks ? */
    bne     SDRAMnobank1

    mr      r17, r16

SDRAMnobank1:
    li      r3, 0x000c          /* get refresh from spd for bank0/1 */
    bl      spdRead
    andi.   r3, r3, 0x007f      /* mask selfrefresh bit */
    li      r4, 0x1800          /* refesh cycle 1536 clocks left shifted 2 */
    cmpli   0, 0, r3, 0x0000    /* 15.6 us ? */
    beq     writeRefresh

    li      r4, 0x0c00          /* refesh cycle 768 clocks left shifted 2 */
    cmpli   0, 0, r3, 0x0002    /* 7.8 us ? */
    beq     writeRefresh

    li      r4, 0x3000          /* refesh cycle 3072 clocks left shifted 2 */
    cmpli   0, 0, r3, 0x0003    /* 31.3 us ? */
    beq     writeRefresh

    li      r4, 0x6000          /* refesh cycle 6144 clocks left shifted 2 */
    cmpli   0, 0, r3, 0x0004    /* 62.5 us ? */
    beq     writeRefresh

    li      r4, 0
    ori     r4, r4, 0xc000      /* refesh cycle 8224 clocks left shifted 2 */
    cmpli   0, 0, r3, 0x0005    /* 125 us ? */
    beq     writeRefresh

    b       memConfErr

writeRefresh:
    lis     r21, 0x0400         /* preset MCCR2 value */
    or      r21, r21, r4

    /* Overwrite MCCR1 */
    lis     r3, MPC106_REG@h
    ori     r3, r3, MPC106_MCCR1
    stwbrx  r3, 0, r1
    eieio
    stwbrx  r20, 0, r2

    /* Overwrite MCCR2 */
    lis     r3, MPC106_REG@h
    ori     r3, r3, MPC106_MCCR2
    stwbrx  r3, 0, r1
    eieio
    stwbrx  r21, 0, r2

    /* set the memory boundary registers for bank 0-3 */
    li      r20, 0
    lis     r23, 0x0303
    lis     r24, 0x0303
    subi    r21, r16, 1         /* calculate end address bank0 */
    li      r22, 1

    cmpi    0, 0, r17, 0        /* bank1 present ? */
    beq     nobank1

    andi.   r3, r16, 0x00ff     /* calculate start address of bank1 */
    andi.   r4, r16, 0x0300
    rlwinm  r3, r3, 8, 16, 23
    or      r20, r20, r3
    or      r23, r23, r4

    add     r16, r16, r17       /* add to total memory size */

    subi    r3, r16, 1          /* calculate end address of bank1 */
    andi.   r4, r3, 0x0300
    andi.   r3, r3, 0x00ff
    rlwinm  r3, r3, 8, 16, 23
    or      r21, r21, r3
    or      r24, r24, r4

    ori     r22, r22, 2         /* enable bank1 */
    b       bankOk
nobank1:
    ori     r23, r23, 0x0300    /* set bank1 start to unused area */
    ori     r24, r24, 0x0300    /* set bank1 end to unused area */
bankOk:
    addi    r3, r29, (Mactivate-MessageBlock)
    bl      Printf
    mr      r3, r16
    bl      OutDec
    addi    r3, r29, (Mact0123e-MessageBlock)
    bl      Printf

/*
 * overwrite MSAR1, MEAR1, EMSAR1, and EMEAR1
 */
    addis   r3, r0, 0x8000      /* ADDR_80 */
    ori     r3, r3, 0x0080      /* MSAR1 */
    stwbrx  r3, 0, r1
    eieio
    stwbrx  r20, 0, r2

    addis   r3, r0, 0x8000      /* ADDR_88 */
    ori     r3, r3, 0x0088      /* EMSAR1 */
    stwbrx  r3, 0, r1
    eieio
    stwbrx  r23, 0, r2

    addis   r3, r0, 0x8000      /* ADDR_90 */
    ori     r3, r3, 0x0090      /* MEAR1 */
    stwbrx  r3, 0, r1
    eieio
    stwbrx  r21, 0, r2

    addis   r3, r0, 0x8000      /* ADDR_98 */
    ori     r3, r3, 0x0098      /* EMEAR1 */
    stwbrx  r3, 0, r1
    eieio
    stwbrx  r24, 0, r2

    addis   r3, r0, 0x8000      /* ADDR_A0 */
    ori     r3, r3, 0x00a0      /* MBER */
    stwbrx  r3, 0, r1
    eieio
    stwbrx  r22, 0, r2

/*
 * delay to let SDRAM go through several initialization/refresh cycles
 */
    lis     r3, 3
    mtctr   r3
memStartWait_1:
    bdnz    memStartWait_1
    eieio

/*
 * set LEDs end
 */
    li      r3, 0xf
    lis     r30, CFG_USR_LED_BASE@h
    stb     r3, 2(r30)
    sync

    mtlr    r13
    blr                         /* EXIT board_asm_init ... */

/*----------------------------------------------------------------------------*/
/*
 * print a message to COM1 in polling mode (r10=COM1 port, r3=(char*)string)
 */

Printf:
    lis     r10, CFG_NS16550_COM1@h /* COM1 base address*/
    ori     r10, r10, CFG_NS16550_COM1@l
WaitChr:
    lbz     r0, 5(r10)          /* read link status */
    eieio
    andi.   r0, r0, 0x40        /* mask transmitter empty bit */
    beq     cr0, WaitChr        /* wait till empty */
    lbzx    r0, r0, r3          /* get char */
    stb     r0, 0(r10)          /* write to transmit reg */
    eieio
    addi    r3, r3, 1           /* next char */
    lbzx    r0, r0, r3          /* get char */
    cmpwi   cr1, r0, 0          /* end of string ? */
    bne     cr1, WaitChr
    blr

/*
 * print a char to COM1 in polling mode (r10=COM1 port, r3=char)
 */
OutChr:
    lis     r10, CFG_NS16550_COM1@h /* COM1 base address*/
    ori     r10, r10, CFG_NS16550_COM1@l
OutChr1:
    lbz     r0, 5(r10)          /* read link status */
    eieio
    andi.   r0, r0, 0x40        /* mask transmitter empty bit */
    beq     cr0, OutChr1        /* wait till empty */
    stb     r3, 0(r10)          /* write to transmit reg */
    eieio
    blr

/*
 * print 8/4/2 digits hex value to COM1 in polling mode (r10=COM1 port, r3=val)
 */
OutHex2:
    li      r9, 4               /* shift reg for 2 digits */
    b       OHstart
OutHex4:
    li      r9, 12              /* shift reg for 4 digits */
    b       OHstart
OutHex:
    li      r9, 28              /* shift reg for 8 digits */
OHstart:
    lis     r10, CFG_NS16550_COM1@h /* COM1 base address*/
    ori     r10, r10, CFG_NS16550_COM1@l
OutDig:
    lbz     r0, 0(r29)          /* slow down dummy read */
    lbz     r0, 5(r10)          /* read link status */
    eieio
    andi.   r0, r0, 0x40        /* mask transmitter empty bit */
    beq     cr0, OutDig
    sraw    r0, r3, r9
    clrlwi  r0, r0, 28
    cmpwi   cr1, r0, 9
    ble     cr1, digIsNum
    addic   r0, r0, 55
    b       nextDig
digIsNum:
    addic   r0, r0, 48
nextDig:
    stb     r0, 0(r10)          /* write to transmit reg */
    eieio
    addic.  r9, r9, -4
    bge     OutDig
    blr

/*
 * print 3 digits hdec value to COM1 in polling mode
 * (r10=COM1 port, r3=val, r7=x00, r8=x0, r9=x, r0, r6=scratch)
 */
OutDec:
    li      r6, 10
    divwu   r0, r3, r6          /* r0 = r3 / 10, r9 = r3 mod 10 */
    mullw   r10, r0, r6
    subf    r9, r10, r3
    mr      r3, r0
    divwu   r0, r3, r6          /* r0 = r3 / 10, r8 = r3 mod 10 */
    mullw   r10, r0, r6
    subf    r8, r10, r3
    mr      r3, r0
    divwu   r0, r3, r6          /* r0 = r3 / 10, r7 = r3 mod 10 */
    mullw   r10, r0, r6
    subf    r7, r10, r3
    lis     r10, CFG_NS16550_COM1@h /* COM1 base address*/
    ori     r10, r10, CFG_NS16550_COM1@l
    or.     r7, r7, r7
    bne     noblank1
    li      r3, 0x20
    b       OutDec4
noblank1:
    addi    r3, r7, 48          /* convert to ASCII */
OutDec4:
    lbz     r0, 0(r29)          /* slow down dummy read */
    lbz     r0, 5(r10)          /* read link status */
    eieio
    andi.   r0, r0, 0x40        /* mask transmitter empty bit */
    beq     cr0, OutDec4
    stb     r3, 0(r10)          /* x00 to transmit */
    eieio
    or.     r7, r7, r8
    beq     OutDec5
    addi    r3, r8, 48          /* convert to ASCII */
OutDec5:
    lbz     r0, 0(r29)          /* slow down dummy read */
    lbz     r0, 5(r10)          /* read link status */
    eieio
    andi.   r0, r0, 0x40        /* mask transmitter empty bit */
    beq     cr0, OutDec5
    stb     r3, 0(r10)          /* x0  to transmit */
    eieio
    addi    r3, r9, 48          /* convert to ASCII */
OutDec6:
    lbz     r0, 0(r29)          /* slow down dummy read */
    lbz     r0, 5(r10)          /* read link status */
    eieio
    andi.   r0, r0, 0x40        /* mask transmitter empty bit */
    beq     cr0, OutDec6
    stb     r3, 0(r10)          /* x   to transmit */
    eieio
    blr

/*
 * hang endless loop
 */
toggleError:                    /* fail type in r6, r7=0xff, toggle LEDs */
    stb     r7, 2(r30)          /* r7 to LED */
    li      r0, 0
    lis     r9, 127
    ori     r9, r9, 65535
toggleError1:
    addic   r0, r0, 1
    cmpw    cr1, r0, r9
    ble     cr1, toggleError1
    stb     r6, 2(r30)          /* r6 to LED */
    li      r0, 0
    lis     r9, 127
    ori     r9, r9, 65535
toggleError2:
    addic   r0, r0, 1
    cmpw    cr1, r0, r9
    ble     cr1, toggleError2
    b       toggleError

/*
 * routines to read from ram spd
 */
spdWaitIdle:
    lis     r0, 0x1             /* timeout for about 100us */
    mtctr   r0
iSpd:
    lbz     r10, 12(r14)
    andi.   r10, r10, 0x20      /* mask and test MBB */
    beq     idle
    bdnz    iSpd
    orc.    r10, r0, r0         /* return -1 to caller */
idle:
    bclr    20, 0               /* return to caller */

waitSpd:
    lis     r0, 0x10            /* timeout for about 1.5ms */
    mtctr   r0
wSpd:
    lbz     r10, 12(r14)
    andi.   r10, r10, 0x82
    cmpli   0, 0, r10, 0x82     /* test MCF and MIF set */
    beq     wend
    bdnz    wSpd
    orc.    r10, r0, r0         /* return -1 to caller */
    bclr    20, 0               /* return to caller */

wend:
    li      r10, 0
    stb     r10, 12(r14)        /* clear status */
    bclr    20, 0               /* return to caller */

/*
 * spdread
 * in:  r3 adr to read
 * out: r3 val or -1 for error
 * uses r10, assumes that r14 points to I2C controller
 */
spdRead:
    mfspr   r25, 8              /* save link register */

    bl      spdWaitIdle
    bne     spdErr

    li      r10, 0x80           /* start with MEN */
    stb     r10, 8(r14)
    eieio

    li      r10, 0xb0           /* start as master */
    stb     r10, 8(r14)
    eieio

    li      r10, 0xa0           /* write device 0xA0 */
    stb     r10, 16(r14)
    eieio
    bl      waitSpd
    bne     spdErr

    lbz     r10, 12(r14)        /* test ACK */
    andi.   r10, r10, 0x01
    bne     gotNoAck

    stb     r3, 16(r14)         /* data address */
    eieio
    bl      waitSpd
    bne     spdErr


    li      r10, 0xb4           /* switch to read - restart */
    stb     r10, 8(r14)
    eieio

    li      r10, 0xa1           /* read device 0xA0 */
    stb     r10, 16(r14)
    eieio
    bl      waitSpd
    bne     spdErr

    li      r10, 0xa8           /* no ACK */
    stb     r10, 8(r14)
    eieio

    lbz     r10, 16(r14)        /* trigger read next byte */
    eieio
    bl      waitSpd
    bne     spdErr

    li      r10, 0x88           /* generate STOP condition */
    stb     r10, 8(r14)
    eieio

    lbz     r3, 16(r14)         /* return read byte */

    mtspr   8, r25              /* restore link register */
    blr

gotNoAck:
    li      r10, 0x80           /* generate STOP condition */
    stb     r10, 8(r14)
    eieio
spdErr:
    orc     r3, r0, r0          /* return -1 */
    mtspr   8, r25              /* restore link register */
    blr

get_lnk_reg:
    mflr    r3                  /* return link reg */
    blr

MessageBlock:

MinitLogo:
    .ascii  "\015\012*** ELTEC Elektronik, Mainz ***\015\012"
    .ascii  "\015\012Initialising RAM\015\012\000"
Mspd01:
    .ascii  "       Reading SPD of SODIMM ...... \000"
MramTyp:
    .ascii  "\015\012\SDRAM with CL=2 at 100 MHz required!\015\012\000"
MramConfErr:
    .ascii  "\015\012\Unsupported SODIMM Configuration!\015\012\000"
Mactivate:
    .ascii  "       Activating \000"
Mact0123e:
    .ascii  " MByte.\015\012\000"
Mok:
    .ascii  "OK \015\012\000"
Mfail:
    .ascii  "FAILED \015\012\000"
MnewLine:
    .ascii  "\015\012\000"
    .align 4