source: rtems/c/src/lib/libbsp/i386/i386ex/start/start.S @ 5c7f274

/*
 *  This file is the main boot and configuration file for the i386ex.  It is
 *  solely responsible for initializing the internal register set to reflect
 *  the proper board configuration.  This version is the "generic" i386ex
 *  startup:
 *
 *    1) 512K flask ROM @3f80000
 *    2) 1 Mb RAM @ 0x0
 *    3) Timer0 used as RTEMS clock ticker, 1 msec tick rate.
 *    4) READY# is generated by CPU
 *
 *  The file is a multi-section file, with sections as follows:
 *     1) interrupt gates,             in section "ints"
 *     2) interrupt descriptor table,  in section "idt"
 *     3) global descriptor table,     in section "gdt"
 *     4) reset                        in section "reset"
 *     5) and initial boot code        in section " initial"
 *
 *  Submitted by:
 *
 *    Erik Ivanenko
 *    University of Toronto
 *    erik.ivanenko@utoronto.ca
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 *
 *  $Id$

changes:
    SetExRegByte(ICW3S  , 0x02 ) # MUST be 0x02 according to intel
    SetExRegByte(ICW3M  , 0x04 ) # IR2 is cascaded internally: was 0x02 => IR1 is cascaded

 */

#include <rtems/asm.h>
#include "macros.inc"
#include "80386ex.inc"

/*
 * NEW_GAS Needed for binutils 2.9.1.0.7 and higher
 */

        EXTERN (boot_card)         /* exits to bspstart   */
        EXTERN (stack_start)       /* defined in startup/linkcmds */
        EXTERN (Clock_exit)

        PUBLIC (Interrupt_descriptor_table)
        PUBLIC ( SYM(IDTR) )
/*      PUBLIC( SYM(_initInternalRegisters) )  */

BEGIN_DATA
SYM(IDTR):      DESC3( SYM(Interrupt_descriptor_table), 0x07ff );

SYM(Interrupt_descriptor_table):   /* Now in data section */
        .rept 256
        .word 0,0,0,0
        .endr

END_DATA

BEGIN_DATA
         PUBLIC (_Global_descriptor_table)

SYM(GDTR):      DESC3( GDT_TABLE, 0x1f ); # one less than the size
SYM (_Global_descriptor_table):
SYM(GDT_TABLE): DESC2(0,0,0,0,0,0);
SYM(GDT_ALIAS): DESC2(32,0x1000,0x0,0x93,0,0x0);
SYM(GDT_CODE):  DESC2(0xffff,0,0x0,0x9B,0xDF,0x00);
SYM(GDT_DATA):  DESC2(0xffff,0,0x0,0x92,0xDF,0x00); # was CF
SYM(GDT_END):

END_DATA

/* This section is the section that is used by the interrupt
   descriptor table.  It is used to provide the IDT with the
   correct vector offsets.  It is for symbol definition only.
*/

        .code16
        .section .reset, "ax"
                PUBLIC ( SYM(reset) )
SYM(reset):
        nop
        cli
#ifdef NEW_GAS
        data32 addr32 jmp     SYM(_initInternalRegisters) /* different section in this file */
#else
        jmp     SYM(_initInternalRegisters) /* different section in this file */
#endif
/*      .code32                              in case this section moves     */
        nop                                 /* required by CHIP LAB to pad out size */
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop

        .section .initial, "ax"
        /* nop */               /* required for linker -- initial jump is to "label - 2"   */
        /* nop */               /* ie. _initInternalRegisters -2 ( which now == .initial ) */
/*
 * Enable access to peripheral register at expanded I/O addresses
 */
SYM(_initInternalRegisters):

        /* .code16 */
        movw    $0x8000 , ax
        outb    al      , $REMAPCFGH
        xchg    al      , ah
        outb    al,$REMAPCFGL
        outw    ax,      $REMAPCFG ;
/*
 * Configure operation of the A20 Address Line
 */
SYM(A20):
        movw    $PORT92 , dx

        inb     dx      , al   # clear A20 port reset
        andb    $0xfe   , al   # b0 Fast Reset(0)=disabled,(1)=reset triggered
        orb     $0x02   , al   # Bit 1 Fast A20 = 0 (always 0) else enabled.
        outb    al      , dx

SYM(Watchdog):
        movw    $WDTSTATUS      , dx    # address the WDT status port
        inb     dx              , al    # get the WDT status
        orb     $0x01           , al    # set the CLKDIS bit
        outb    al              , dx    # disable the clock to the WDT

/*
 * Initialize Refresh Control Unit for:
 *      Refresh Address = 0x0000

 *      Refresh gate between rows is 15.6 uSec
 *      Using a CLK2 frequency of 50Mhz ( 25Mhz CPU )
 *      The refresh unit is enabled
 *      The refresh pin is not used.
 */

SYM(InitRCU):
        SetExRegWord( RFSCIR , 390)     # refresh interval was 390, tried 312
        SetExRegWord( RFSBAD , 0x0)     # base address
        SetExRegWord( RFSADD , 0x0)     # address register
        SetExRegWord( RFSCON , 0x8000)  # enable bit

/*
 * Initialize clock and power mgmt unit for:
 *      Clock Frequency = 50 Mhz
 *      Prescaled clock output = 1 Mhz
 *      Normal halt instructions
 */

SYM(InitClk):
        SetExRegByte( PWRCON, 0x0 )
        SetExRegWord( CLKPRS, 0x17)   # 0x13 for 1.19318 MHz.  0x17 for 1MHz.

/**************************************************************
 * Initialize the Pin Configurations
 *************************************************************/

/*
 *      Initialize I/O port 1 for:
 *      PIN 0 = 1,      DCD0# to package pin
 *      PIN 1 = 1,      RTS0# to package pin
 *      PIN 2 = 1,      DTR0# to package pin
 *      PIN 3 = 1,      DSR0# to package pin
 *      PIN 4 = 1,      RI0# to package pin
 *      PIN 5 = 0,      Outport (FLASH Vpp Enable, 0=Enable 1=Disable)
 *      PIN 6 = 0,      Outport (P16_HOLD to 386ex option header JP7 pin 5)
 *      PIN 7 = 0,      Outport (P17_HOLD to 386ex option header JP7 pin 3)
 */

SYM(InitPort1):
        SetExRegByte( P1LTC     , 0xff )
        SetExRegByte( P1DIR     , 0x0  )
        SetExRegByte( P1CFG     , 0x1f)

/*
 *      Initialize I/O port 2 for:
 *      PIN 0 = 0,      Outport (P20_CS0# to 386ex option header JP7 pin 11)
 *      PIN 1 = 0,      Outport (P21_CS1# to 386ex option header JP7 pin 9)
 *      PIN 2 = 1,      CS2# (SMRAM) If not using CS2 can be configured as.?
 *      PIN 3 = 0,      Outport ( no connect )
 *      PIN 4 = 1,      CS#4 (DRAM)
 *      PIN 5 = 1,      RXD0 input. See not for I/0 port 1 pins 1-4
 *      PIN 6 = 1,      TXD0 output.
 *      PIN 7 = 1,      CTS0# input.
 */

SYM(InitPort2):
        SetExRegByte( P2LTC     , 0xff )
        SetExRegByte( P2DIR     , 0x0  )
        SetExRegByte( P2CFG     , 0xfe)

/*
 *      Initialize I/O port 3 P3CFG
 *      PIN 0 = 1,      TMROUT0 to package pin
 *      PIN 1 = 0,      (TMROUT1 to 386ex option header JP7 pin 23)
 *      PIN 2 = 0,      INT0 (IR1) disabled, (P3.2 out to JP7 pin 21)
 *      PIN 3 = 0,      INT1 (IR5) disbled (P3.3  to option header JP7 pin 19)
 *      PIN 4 = 0,      INT2 (IR6) disbled (P3.4 to option header JP7 pin 17)
 *      PIN 5 = 0,      INT2 (IR7) disabled (P3.5 to 386ex header JP7 pin 15)
 *      PIN 6 = 0,      Inport (Debugger Break P3.6/PWRD to package pin )
 *                      P3.6 selected
 *      PIN 7 = 0,      COMCLK output disabled, 1.8432 Mhz OSC1 oscillator.
 *                      ( Debbugger uses COMCLK as the clocking source )
 *                      P3.7 connected to package pin.
 */

SYM(InitPort3):
        SetExRegByte( P3LTC     , 0xff )
        SetExRegByte( P3DIR     , 0x41 )
        SetExRegByte( P3CFG     , 0x09 )  # can check TMROUT0
/*
 *      Initialize Peripheral Pin Configurations:
 *      PIN 0 = 1,      RTS1# to package pin
 *      PIN 1 = 1,      DTR1# to package pin
 *      PIN 2 = 1,      TXD1 out to package pin
 *      PIN 3 = 0,      EOP#/TC
 *      PIN 4 = 0,      DACK0#
 *      PIN 5 = 1,      Timer2
 *      PIN 6 = 0,      0 => CS6# connected to package pin
 *      PIN 7 = 0,      Don't care
 */

SYM(InitPeriph):
        SetExRegByte( PINCFG , 0x24)

/*
 *      Initialize the Asynchronous Serial Ports:
 *      BIT 7 = 1,      Internal SIO1 modem signals
 *      BIT 6 = 1,      Internal SIO0 modem signals
 *      BIT 2 = 0,      PSCLK for SSIO clock
 *      BIT 1 = 1,      SERCLK for SIO1 clock
 *      BIT 0 = 1,      SERCLK for SIO0 clock
 */

SYM(InitSIO):
        SetExRegByte( SIOCFG, 0xC3 ) # SIOn clocked internally

        SetExRegByte( LCR0,     0x80 )  # latch DLL0, DLH0
        SetExRegByte( DLL0, 0x51 )      # 0x51 sets to 9600 baud, 0x28=19.2k, 0x7 -> 115.2k
        SetExRegByte( DLH0, 0x00 )  # 0x145 is 2400 baud
        SetExRegByte( LCR0, 0x03 )  # enable r/w buffers, IER0 accessible
                                    # mode 8-n-1
        SetExRegByte( IER0, 0x00 )  # was 0x0f All interrupts detected

        SetExRegByte( LCR1, 0x80 )  # latch DLL0, DLH0
        SetExRegByte( DLL1, 0x51 )  # 0x51 set to 9600 baud, 0x7 = 115200
        SetExRegByte( DLH1, 0x00 )  # 0x145 is 2400 baud
        SetExRegByte( LCR1, 0x03 )  # enable r/w buffers, IER1 accessible
                                        # reg 8-n-1
        SetExRegByte( IER1, 0x00 )  # was 0x0f - All interrupts detected

SYM(InitMCR):
/*
 *      Initialize Timer for:
 *      BIT 7 = 1,      Timer clocks disabled
 *      BIT 6 = 0,      Reserved
 *      BIT 5 = 1,      TMRCLK2 instead of Vcc to Gate2
 *      BIT 4 = 0,      PSCLK to CLK2
 *      BIT 3 = 1,      TMRCLK1 instead of Vcc to Gate1
 *      BIT 2 = 0,      PSCLK to Gate1
 *      BIT 1 = 0,      Vcc to Gate0
 *      BIT 0 = 0,      PSCLK to Gate0
 */

SYM(InitTimer):
        SetExRegByte(TMRCFG , 0x80 ) # All counters disabled, Gates 0,1
                                     # and 2 are set to Vcc

        SetExRegByte(TMRCON , 0x34 ) # prepare to write counter 0 LSB,MSB
        SetExRegByte(TMR0   , 0x00 ) # sfa
        SetExRegByte(TMR0   , 0x00 ) # sfa

        SetExRegByte(TMRCON , 0x70 ) # mode 0 disables on Gate= Vcc
        SetExRegByte(TMR1   , 0x00 ) # sfa
        SetExRegByte(TMR1   , 0x00 ) # sfa

        SetExRegByte(TMRCON , 0xB0 ) # mode 0 disables on gate =Vcc
        SetExRegByte(TMR2   , 0x00 ) #
        SetExRegByte(TMR2   , 0x00 ) #

        SetExRegByte(TMRCFG , 0x80 ) # Enable = 0x00

/*
 *      Initialize the DMACFG register for:
 *      BIT 7    = 1  , Disable DACK#1
 *      BITs 6:4 = 100, TMROUT2 connected to DRQ1
 *      BIT 3    = 1  , Disable DACK0#
 *      BIT 2:0  = 000, Pin is connected to DRQ0
 */

        SetExRegByte(DMACFG , 0xC0  )
        SetExRegByte(DMACMD1, 0x00 ) # disable both DMA channels
        SetExRegByte(DMAMOD1, 0x40 )
/*
 *      Initialize the INTCFG register for:
 *      BIT 7 = 0,      8259 cascade disabled
 *      BIT 3 = 0,      SLAVE IR6 connected to Vss
 *      BIT 2 = 0,      SLAVE IR5 connected to Vss
 *      BIT 1 = 0,      SLAVE IR1 connected to SSIOINT
 *      BIT 0 = 0,      SLAVE IR0 connected to Vss
 */

SYM(InitInt):

        cli                               # !
/*      SetExRegByte(OCW3S, 0x20)  # address the Slave status port
        movw    $OCW3S  , dx
        inb     dx      , al    # Read the IRR.

        SetExRegByte(OCW3M, 0x20)  # address the Master status port
        movw    $OCW3M  , dx
        inb     dx      , al    # Read the IRR.
*/

        SetExRegByte(ICW1S  , 0x11 ) # EDGE TRIGGERED
        SetExRegByte(ICW2S  , 0x28 ) # Slave base vector after Master
        SetExRegByte(ICW3S  , 0x02 ) # slave cascaded to IR2 on master
        SetExRegByte(ICW4S  , 0x01 ) # must be 0x01

        SetExRegByte(ICW1M  , 0x11 ) # edge triggered
        SetExRegByte(ICW2M  , 0x20 ) # base vector starts at byte 32
        SetExRegByte(ICW3M  , 0x04)  # IR2 is cascaded internally
        SetExRegByte(ICW4M  , 0x01 ) # fully nested mode

        SetExRegByte(OCW1M  , 0xde )    # IR0  only = 0xfe.
                                        # for IR5 and IR0 active use 0xde
                                        # for IR0 and IR2 use 0xfa
        SetExRegByte(INTCFG , 0x00 )

SYM(SetCS4):
        SetExRegWord(CS4ADL , 0x702)         #Configure chip select 4
        SetExRegWord(CS4ADH , 0x00)
        SetExRegWord(CS4MSKH, 0x03F)
        SetExRegWord(CS4MSKL, 0xFC01)

SYM(SetUCS1):
        SetExRegWord(UCSADL , 0x0304)      # 512K block starting at 0x80000 until 0x3f80000
        SetExRegWord(UCSADH , 0x03F8)
        SetExRegWord(UCSMSKH, 0x03F7)
        SetExRegWord(UCSMSKL, 0xFC01)     # configure upper chip select

/******************************************************
* The GDT must be in RAM since it must be writeable,
* So, move the whole data section down.
********************************************************/

        movw $ _ram_data_offset , di
        movw $ _ram_data_segment, cx
        mov  cx                 , es

        movw $ _data_size       , cx
        movw $ _rom_data_segment, ax
        movw $ _rom_data_offset , si
        mov  ax                 , ds

        repne
        movsb

/*****************************
 * Load the Global Descriptor
 * Table Register
 ****************************/

#ifdef NEW_GAS
        data32 addr32 lgdt SYM(GDTR) #  location of GDT
#else
        lgdt SYM(GDTR) #  location of GDT
#endif

SYM(SetUCS):
        SetExRegWord(UCSADL, 0x0702)      # now 512K starting at 0x3f80000.
        SetExRegWord(UCSADH, 0x03f8)
        SetExRegWord(UCSMSKH, 0x0007)
        SetExRegWord(UCSMSKL, 0xFC01)     # configure upper chip select

        /*
         * SRAM chip select:     16 bit bus size,starting 16Mb, size 512k,
         *                       4 waits
         */

#ifdef UT_I386EX

SYM(SetCS1):
        SetExRegWord(CS1ADL,  0x0000)
        SetExRegWord(CS1ADH,  0x000E)
        SetExRegWord(CS1MSKH, 0x0000)
        SetExRegWord(CS1MSKL, 0x0001)

SYM(SetCS2):
        SetExRegWord(CS2ADL,  0x0704)
        SetExRegWord(CS2ADH,  0x0100)
        SetExRegWord(CS2MSKH, 0x0003)
        SetExRegWord(CS2MSKL, 0xfc01)

        /*
         * Real-time clock:     8 bit bus size, starting@16Mb+512K, size 32k
         *                       4 waits
         */
SYM(SetCS3):
        SetExRegWord(CS3ADL,  0x0504)
        SetExRegWord(CS3ADH,  0x0108)
        SetExRegWord(CS3MSKH, 0x0000)
        SetExRegWord(CS3MSKL, 0x7c01)

#endif
/***************************
 * Switch to Protected Mode
 ***************************/

        mov     cr0, eax
        orw     $0x1, ax
        mov     eax, cr0

/**************************
 * Flush prefetch queue,
 * and load CS selector
 *********************/

        ljmpl $ GDT_CODE_PTR , $  SYM(_load_segment_registers) # sets the code selector

/*
 * Load the segment registers
 */
SYM(_load_segment_registers):
        .code32
        pLOAD_SEGMENT( GDT_DATA_PTR, fs)
        pLOAD_SEGMENT( GDT_DATA_PTR, gs)
        pLOAD_SEGMENT( GDT_DATA_PTR, ss)
        pLOAD_SEGMENT( GDT_DATA_PTR, ds)
        pLOAD_SEGMENT( GDT_DATA_PTR, es)

/*
 *  Set up the stack
 */

SYM(lidtr):
        lidt    SYM(IDTR)

SYM (_establish_stack):
        movl    $end, eax               # stack starts right after bss
        movl    $stack_origin, esp      # this is the high starting address
        movl    $stack_origin, ebp

/*
 *  Zero out the BSS segment
 */
SYM (zero_bss):
        cld                             # make direction flag count up
        movl    $ SYM (end),ecx        # find end of .bss
        movl    $ SYM (_bss_start),edi # edi = beginning of .bss
        subl    edi,ecx               # ecx = size of .bss in bytes
        shrl    ecx                    # size of .bss in longs
        shrl    ecx
        xorl    eax,eax               # value to clear out memory
        repne                           # while ecx != 0
        stosl                           #   clear a long in the bss

/*
 *  Transfer control to User's Board Support Package
 */
        pushl   $0                       # environp
        pushl   $0                       # argv
        pushl   $0                       # argc

        movw    $0xFFFB, SYM(i8259s_cache)      # ICU mask values reflect
                                                # initial ICU state
        call SYM(boot_card)
        addl    $12,esp

        cli                              # stops interrupts from being processed after hlt!
        hlt                              # shutdown

END