l1.c

讲述linux的初始化过程

		  int	   ch,           /* subchannel for this message */
		  char    *msg,          /* message buffer */
		  int      msg_len,      /* size of message buffer */
                  l1addr_t addr_task,    /* target system controller task */
                  short    req_code,     /* 16-bit request code */
                  int      req_nargs,    /* # of arguments (varargs) passed */
                  ... )                 /* any additional parameters */
{
    uint32_t buf32;   /* 32-bit buffer used to bounce things around */
    void *bufptr;       /* used to hold command argument addresses */
    va_list al;         /* variable argument list */
    int index;          /* current index into msg buffer */
    int argno;          /* current position in varargs list */
    int l1_argno;       /* running total of arguments to l1 */
    int l1_arg_t;       /* argument type/length */
    int l1_argno_byte;  /* offset of argument count byte */

    index = argno = 0;

    /* set up destination address */
    if( (msg_len -= sizeof( buf32 )) < 0 )
	return -1;
    L1_ADDRESS_TO_TASK( &buf32, sc->subch[ch].target, addr_task );
    COPY_INT_TO_BUFFER(msg, index, buf32);

    /* copy request code */
    if( (msg_len -= 2) < 0 )
	return( -1 );
    msg[index++] = ((req_code >> 8) & 0xff);
    msg[index++] = (req_code & 0xff);

    if( !req_nargs ) {
        return index;
    }

    /* reserve a byte for the argument count */
    if( (msg_len -= 1) < 0 )
	return( -1 );
    l1_argno_byte = index++;
    l1_argno = 0;

    /* copy additional arguments */
    va_start( al, req_nargs );
    while( argno < req_nargs ) {
        l1_argno++;
        l1_arg_t = va_arg( al, int ); argno++;
        switch( l1_arg_t )
        {
          case L1_ARG_INT:
	    if( (msg_len -= (sizeof( buf32 ) + 1)) < 0 )
		return( -1 );
            msg[index++] = L1_ARG_INT;
            buf32 = (unsigned)va_arg( al, int ); argno++;
	    COPY_INT_TO_BUFFER(msg, index, buf32);
            break;

          case L1_ARG_ASCII:
            bufptr = va_arg( al, char* ); argno++;
	    if( (msg_len -= (strlen( bufptr ) + 2)) < 0 )
		return( -1 );
            msg[index++] = L1_ARG_ASCII;
            strcpy( (char *)&(msg[index]), (char *)bufptr );
            index += (strlen( bufptr ) + 1); /* include terminating null */
            break;

	  case L1_ARG_UNKNOWN:
              {
                  int arglen;
		  
                  arglen = va_arg( al, int ); argno++;
                  bufptr = va_arg( al, void* ); argno++;
		  if( (msg_len -= (arglen + 1)) < 0 )
		      return( -1 );
                  msg[index++] = L1_ARG_UNKNOWN | arglen;
                  BCOPY( bufptr, &(msg[index]), arglen  );
                  index += arglen;
		  break;
              }
	  
	  default: /* unhandled argument type */
	    return -1;
        }
    }

    va_end( al );
    msg[l1_argno_byte] = l1_argno;

    return index;
}



/* sc_interpret_resp verifies an L1 response to a bedrock request, and
 * breaks the response data up into the constituent parts.  If the
 * response message indicates error, or if a mismatch is found in the
 * expected number and type of arguments, an error is returned.  The
 * arguments to this function work very much like the arguments to
 * sc_construct_msg, above, except that L1_ARG_INTs must be followed
 * by a _pointer_ to an integer that can be filled in by this function.
 */
int
sc_interpret_resp( char *resp,          /* buffer received from L1 */
                   int   resp_nargs,    /* number of _varargs_ passed in */
                   ... )
{
    uint32_t buf32;   /* 32-bit buffer used to bounce things around */
    void *bufptr;       /* used to hold response field addresses */
    va_list al;         /* variable argument list */
    int index;          /* current index into response buffer */
    int argno;          /* current position in varargs list */
    int l1_fldno;       /* number of resp fields received from l1 */
    int l1_fld_t;       /* field type/length */

    index = argno = 0;

#if defined(L1_DEBUG)
#define DUMP_RESP							  \
    {									  \
	int ix;								  \
        char outbuf[512];						  \
        sprintf( outbuf, "sc_interpret_resp error line %d: ", __LINE__ ); \
	for( ix = 0; ix < 16; ix++ ) {					  \
	    sprintf( &outbuf[strlen(outbuf)], "%x ", resp[ix] );	  \
	}								  \
	printk( "%s\n", outbuf );					  \
    }
#else
#define DUMP_RESP
#endif /* L1_DEBUG */

    /* check response code */
    COPY_BUFFER_TO_INT(resp, index, buf32);
    if( buf32 != L1_RESP_OK ) {
	DUMP_RESP;
        return buf32;
    }

    /* get number of response fields */
    l1_fldno = resp[index++];

    va_start( al, resp_nargs );

    /* copy out response fields */
    while( argno < resp_nargs ) {
        l1_fldno--;
        l1_fld_t = va_arg( al, int ); argno++;
        switch( l1_fld_t )
        {
          case L1_ARG_INT:
            if( resp[index++] != L1_ARG_INT ) {
                /* type mismatch */
		va_end( al );
		DUMP_RESP;
		return -1;
            }
            bufptr = va_arg( al, int* ); argno++;
	    COPY_BUFFER_TO_BUFFER(resp, index, bufptr);
            break;

          case L1_ARG_ASCII:
            if( resp[index++] != L1_ARG_ASCII ) {
                /* type mismatch */
		va_end( al );
		DUMP_RESP;
                return -1;
            }
            bufptr = va_arg( al, char* ); argno++;
            strcpy( (char *)bufptr, (char *)&(resp[index]) );
            /* include terminating null */
            index += (strlen( &(resp[index]) ) + 1);
            break;

          default:
	    if( (l1_fld_t & L1_ARG_UNKNOWN) == L1_ARG_UNKNOWN )
	    {
		int *arglen;
		
		arglen = va_arg( al, int* ); argno++;
		bufptr = va_arg( al, void* ); argno++;
		*arglen = ((resp[index++] & ~L1_ARG_UNKNOWN) & 0xff);
		BCOPY( &(resp[index]), bufptr, *arglen  );
		index += (*arglen);
	    }
	    
	    else {
		/* unhandled type */
		va_end( al );
		DUMP_RESP;
		return -1;
	    }
        }
    }
    va_end( al );
  
    if( (l1_fldno != 0) || (argno != resp_nargs) ) {
        /* wrong number of arguments */
	DUMP_RESP;
        return -1;
    }
    return 0;
}




/* sc_send takes as arguments a system controller struct, a
 * buffer which contains a Bedrock<->L1 "request" message,
 * the message length, and the subchannel (presumably obtained
 * from an earlier invocation of sc_open) over which the
 * message is to be sent.  The final argument ("wait") indicates
 * whether the send is to be performed synchronously or not.
 *
 * sc_send returns either zero or an error value.  Synchronous sends 
 * (wait != 0) will not return until the data has actually been sent
 * to the UART.  Synchronous sends generally receive privileged
 * treatment.  The intent is that they be used sparingly, for such
 * purposes as kernel printf's (the "ducons" routines).  Run-of-the-mill
 * console output and L1 requests should NOT use a non-zero value
 * for wait.
 */
int
sc_send( l1sc_t *sc, int ch, char *msg, int len, int wait )
{
    char type_and_subch;
    int result;

    if( (ch < 0) || ( ch >= BRL1_NUM_SUBCHANS) ) {
        return SC_BADSUBCH;
    }

    /* Verify that this is an open subchannel
     */
    if( sc->subch[ch].use == BRL1_SUBCH_FREE )
    {
        return SC_NOPEN;
    }
       
    type_and_subch = (BRL1_REQUEST | ((u_char)ch));
    result = brl1_send( sc, msg, len, type_and_subch, wait );

    /* If we sent as much as we asked to, return "ok". */
    if( result == len )
	return( SC_SUCCESS );

    /* Or, if we sent less, than either the UART is busy or
     * we're trying to send too large a packet anyway.
     */
    else if( result >= 0 && result < len )
	return( SC_BUSY );

    /* Or, if something else went wrong (result < 0), then
     * return that error value.
     */
    else
	return( result );
}



/* subch_pull_msg pulls a message off the receive queue for subch
 * and places it the buffer pointed to by msg.  This routine should only
 * be called when the caller already knows a message is available on the
 * receive queue (and, in the kernel, only when the subchannel data lock
 * is held by the caller).
 */
static void
subch_pull_msg( brl1_sch_t *subch, char *msg, int *len )
{
    sc_cq_t *q;         /* receive queue */
    int before_wrap,    /* packet may be split into two different       */
        after_wrap;     /*   pieces to acommodate queue wraparound      */

    /* pull message off the receive queue */
    q = subch->iqp;

    cq_rem( q, *len );   /* remove length byte and store */
    cq_discard( q );     /* remove type/subch byte and discard */

    if ( *len > 0 )
	(*len)--;        /* don't count type/subch byte in length returned */

    if( (q->opos + (*len)) > BRL1_QSIZE ) {
        before_wrap = BRL1_QSIZE - q->opos;
        after_wrap = (*len) - before_wrap;
    }
    else {
        before_wrap = (*len);
        after_wrap = 0;
    }

    BCOPY( q->buf + q->opos, msg, before_wrap  );
    if( after_wrap ) {
        BCOPY( q->buf, msg + before_wrap, after_wrap  );
	q->opos = after_wrap;
    }
    else {
	q->opos = ((q->opos + before_wrap) & (BRL1_QSIZE - 1));
    }
    atomicAddInt( &(subch->packet_arrived), -1 );
}


/* sc_recv_poll can be called as a blocking or non-blocking function;
 * it attempts to pull a message off of the subchannel specified
 * in the argument list (ch).
 *
 * The "block" argument, if non-zero, is interpreted as a timeout
 * delay (to avoid permanent waiting).
 */

int
sc_recv_poll( l1sc_t *sc, int ch, char *msg, int *len, uint64_t block )
{
    int pl;             /* lock cookie */
    int is_msg = 0;
    brl1_sch_t *subch = &(sc->subch[ch]);

    rtc_time_t exp_time = rtc_time() + block;

    /* sanity check-- make sure this is an open subchannel */
    if( subch->use == BRL1_SUBCH_FREE )
	return( SC_NOPEN );

    do {

        /* kick the next lower layer and see if it pulls anything in
         */
	brl1_receive( sc );
	is_msg = subch->packet_arrived;

    } while( block && !is_msg && (rtc_time() < exp_time) );

    if( !is_msg ) {
	/* no message and we didn't care to wait for one */
	return( SC_NMSG );
    }

    SUBCH_DATA_LOCK( subch, pl );
    subch_pull_msg( subch, msg, len );
    SUBCH_DATA_UNLOCK( subch, pl );

    return( SC_SUCCESS );
}
    

/* Like sc_recv_poll, sc_recv_intr can be called in either a blocking
 * or non-blocking mode.  Rather than polling until an appointed timeout,
 * however, sc_recv_intr sleeps on a syncrhonization variable until a
 * signal from the lower layer tells us that a packet has arrived.
 *
 * sc_recv_intr can't be used with remote (router) L1s.
 */
int
sc_recv_intr( l1sc_t *sc, int ch, char *msg, int *len, uint64_t block )
{
    int pl;             /* lock cookie */
    int is_msg = 0;
    brl1_sch_t *subch = &(sc->subch[ch]);

    do {
	SUBCH_DATA_LOCK(subch, pl);
	is_msg = subch->packet_arrived;
	if( !is_msg && block ) {
	    /* wake me when you've got something */
	    subch->rx_notify = sc_data_ready;
	    sv_wait( &(subch->arrive_sv), 0, &(subch->data_lock), pl );
	    if( subch->use == BRL1_SUBCH_FREE ) {
		/* oops-- somebody closed our subchannel while we were
		 * sleeping!
		 */

		/* no need to unlock since the channel's closed anyhow */
		return( SC_NOPEN );
	    }
	}
    } while( !is_msg && block );

    if( !is_msg ) {
	/* no message and we didn't care to wait for one */
	SUBCH_DATA_UNLOCK( subch, pl );
	return( SC_NMSG );
    }

    subch_pull_msg( subch, msg, len );
    SUBCH_DATA_UNLOCK( subch, pl );

    return( SC_SUCCESS );
}

/* sc_command implements a (blocking) combination of sc_send and sc_recv.
 * It is intended to be the SN1 equivalent of SN0's "elsc_command", which
 * issued a system controller command and then waited for a response from
 * the system controller before returning.
 *
 * cmd points to the outgoing command; resp points to the buffer in
 * which the response is to be stored.  Both buffers are assumed to
 * be the same length; if there is any doubt as to whether the
 * response buffer is long enough to hold the L1's response, then
 * make it BRL1_QSIZE bytes-- no Bedrock<->L1 message can be any
 * bigger.
 *
 * Be careful using the same buffer for both cmd and resp; it could get
 * hairy if there were ever an L1 command reqeuest that spanned multiple
 * packets.  (On the other hand, that would require some additional
 * rewriting of the L1 command interface anyway.)
 */
#define __RETRIES	50
#define __WAIT_SEND	( sc->uart != BRL1_LOCALUART )
#define __WAIT_RECV	10000000


int
sc_command( l1sc_t *sc, int ch, char *cmd, char *resp, int *len )
{
#ifndef CONFIG_SERIAL_SGI_L1_PROTOCOL
    return SC_NMSG;
#else
    int result;
    int retries;

    if ( IS_RUNNING_ON_SIMULATOR() )
    	return SC_NMSG;

    retries = __RETRIES;

    while( (result = sc_send( sc, ch, cmd, *len, __WAIT_SEND )) < 0 ) {
	if( result == SC_BUSY ) {
	    retries--;
	    if( retries <= 0 )
		return result;
	    uart_delay(500);
	}
	else {
	    return result;
	}
    }
    
    /* block on sc_recv_* */
#ifdef notyet
    if( sc->uart == BRL1_LOCALUART ) {
	return( sc_recv_intr( sc, ch, resp, len, __WAIT_RECV ) );
    }
    else
#endif
    {
	return( sc_recv_poll( sc, ch, resp, len, __WAIT_RECV ) );
    }
#endif /* CONFIG_SERIAL_SGI_L1_PROTOCOL */
}

/* sc_command_kern is a knuckle-dragging, no-patience version of sc_command
 * used in situations where the kernel has a command that shouldn't be
 * delayed until the send buffer clears.  sc_command should be used instead
 * under most circumstances.
 */
int
sc_command_kern( l1sc_t *sc, int ch, char *cmd, char *resp, int *len )
{
#ifndef CONFIG_SERIAL_SGI_L1_PROTOCOL
    return SC_NMSG;
#else
    int result;

    if ( IS_RUNNING_ON_SIMULATOR() )
    	return SC_NMSG;

    if( (result = sc_send( sc, ch, cmd, *len, 1 )) < 0 ) {
	return result;
    }

    return( sc_recv_poll( sc, ch, resp, len, __WAIT_RECV ) );
#endif /* CONFIG_SERIAL_SGI_L1_PROTOCOL */
}



/* sc_poll checks the queue corresponding to the given
 * subchannel to see if there's anything available.  If
 * not, it kicks the brl1 layer and then checks again.
 *
 * Returns 1 if input is available on the given queue,
 * 0 otherwise.
 */
int
sc_poll( l1sc_t *sc, int ch )
{
    brl1_sch_t *subch = &(sc->subch[