specialix.c

讲述linux的初始化过程

	if (bp->flags & SX_BOARD_ACTIVE) 
		return 0;

	error = request_irq(bp->irq, sx_interrupt, SA_INTERRUPT, "specialix IO8+", bp);

	if (error) 
		return error;

	turn_ints_on (bp);
	bp->flags |= SX_BOARD_ACTIVE;

	MOD_INC_USE_COUNT;
	return 0;
}


/* Called with disabled interrupts */
extern inline void sx_shutdown_board(struct specialix_board *bp)
{
	if (!(bp->flags & SX_BOARD_ACTIVE))
		return;
	
	bp->flags &= ~SX_BOARD_ACTIVE;
	
#if SPECIALIX_DEBUG > 2
	printk ("Freeing IRQ%d for board %d.\n", bp->irq, board_No (bp));
#endif
	free_irq(bp->irq, bp);

	turn_ints_off (bp);

	MOD_DEC_USE_COUNT;
}


/*
 * Setting up port characteristics. 
 * Must be called with disabled interrupts
 */
static void sx_change_speed(struct specialix_board *bp, struct specialix_port *port)
{
	struct tty_struct *tty;
	unsigned long baud;
	long tmp;
	unsigned char cor1 = 0, cor3 = 0;
	unsigned char mcor1 = 0, mcor2 = 0;
	static int again;
	
	if (!(tty = port->tty) || !tty->termios)
		return;

	port->IER  = 0;
	port->COR2 = 0;
	/* Select port on the board */
	sx_out(bp, CD186x_CAR, port_No(port));

	/* The Specialix board doens't implement the RTS lines.
	   They are used to set the IRQ level. Don't touch them. */
	if (SX_CRTSCTS(tty))
		port->MSVR = MSVR_DTR | (sx_in(bp, CD186x_MSVR) & MSVR_RTS);
	else
		port->MSVR =  (sx_in(bp, CD186x_MSVR) & MSVR_RTS);
#ifdef DEBUG_SPECIALIX
	printk (KERN_DEBUG "sx: got MSVR=%02x.\n", port->MSVR);
#endif
	baud = C_BAUD(tty);
	
	if (baud & CBAUDEX) {
		baud &= ~CBAUDEX;
		if (baud < 1 || baud > 2) 
			port->tty->termios->c_cflag &= ~CBAUDEX;
		else
			baud += 15;
	}
	if (baud == 15) {
		if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
			baud ++;
		if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
			baud += 2;
	}
	
	
	if (!baud_table[baud]) {
		/* Drop DTR & exit */
#ifdef SPECIALIX_DEBUG
		printk (KERN_DEBUG "Dropping DTR...  Hmm....\n");
#endif
		if (!SX_CRTSCTS (tty)) {
			port -> MSVR &= ~ MSVR_DTR;
			sx_out(bp, CD186x_MSVR, port->MSVR );
		} 
#ifdef DEBUG_SPECIALIX
		else
			printk (KERN_DEBUG "Can't drop DTR: no DTR.\n");
#endif
		return;
	} else {
		/* Set DTR on */
		if (!SX_CRTSCTS (tty)) {
			port ->MSVR |= MSVR_DTR;
		}
	}
	
	/*
	 * Now we must calculate some speed depended things 
	 */

	/* Set baud rate for port */
	tmp = port->custom_divisor ;
	if ( tmp )
		printk (KERN_INFO "sx%d: Using custom baud rate divisor %ld. \n"
		                  "This is an untested option, please be carefull.\n",
		                  port_No (port), tmp);
	else
		tmp = (((SX_OSCFREQ + baud_table[baud]/2) / baud_table[baud] +
		         CD186x_TPC/2) / CD186x_TPC);

	if ((tmp < 0x10) && time_before(again, jiffies)) { 
		again = jiffies + HZ * 60;
		/* Page 48 of version 2.0 of the CL-CD1865 databook */
		if (tmp >= 12) {
			printk (KERN_INFO "sx%d: Baud rate divisor is %ld. \n"
			        "Performance degradation is possible.\n"
			        "Read specialix.txt for more info.\n",
			        port_No (port), tmp);
		} else {
			printk (KERN_INFO "sx%d: Baud rate divisor is %ld. \n"
			        "Warning: overstressing Cirrus chip. "
			        "This might not work.\n"
			        "Read specialix.txt for more info.\n", 
			        port_No (port), tmp);
		}
	}

	sx_out(bp, CD186x_RBPRH, (tmp >> 8) & 0xff); 
	sx_out(bp, CD186x_TBPRH, (tmp >> 8) & 0xff); 
	sx_out(bp, CD186x_RBPRL, tmp & 0xff); 
	sx_out(bp, CD186x_TBPRL, tmp & 0xff);

	if (port->custom_divisor) {
		baud = (SX_OSCFREQ + port->custom_divisor/2) / port->custom_divisor;
		baud = ( baud + 5 ) / 10;
	} else 
		baud = (baud_table[baud] + 5) / 10;   /* Estimated CPS */

	/* Two timer ticks seems enough to wakeup something like SLIP driver */
	tmp = ((baud + HZ/2) / HZ) * 2 - CD186x_NFIFO;		
	port->wakeup_chars = (tmp < 0) ? 0 : ((tmp >= SERIAL_XMIT_SIZE) ?
					      SERIAL_XMIT_SIZE - 1 : tmp);
	
	/* Receiver timeout will be transmission time for 1.5 chars */
	tmp = (SPECIALIX_TPS + SPECIALIX_TPS/2 + baud/2) / baud;
	tmp = (tmp > 0xff) ? 0xff : tmp;
	sx_out(bp, CD186x_RTPR, tmp);
	
	switch (C_CSIZE(tty)) {
	 case CS5:
		cor1 |= COR1_5BITS;
		break;
	 case CS6:
		cor1 |= COR1_6BITS;
		break;
	 case CS7:
		cor1 |= COR1_7BITS;
		break;
	 case CS8:
		cor1 |= COR1_8BITS;
		break;
	}
	
	if (C_CSTOPB(tty)) 
		cor1 |= COR1_2SB;
	
	cor1 |= COR1_IGNORE;
	if (C_PARENB(tty)) {
		cor1 |= COR1_NORMPAR;
		if (C_PARODD(tty)) 
			cor1 |= COR1_ODDP;
		if (I_INPCK(tty)) 
			cor1 &= ~COR1_IGNORE;
	}
	/* Set marking of some errors */
	port->mark_mask = RCSR_OE | RCSR_TOUT;
	if (I_INPCK(tty)) 
		port->mark_mask |= RCSR_FE | RCSR_PE;
	if (I_BRKINT(tty) || I_PARMRK(tty)) 
		port->mark_mask |= RCSR_BREAK;
	if (I_IGNPAR(tty)) 
		port->mark_mask &= ~(RCSR_FE | RCSR_PE);
	if (I_IGNBRK(tty)) {
		port->mark_mask &= ~RCSR_BREAK;
		if (I_IGNPAR(tty)) 
			/* Real raw mode. Ignore all */
			port->mark_mask &= ~RCSR_OE;
	}
	/* Enable Hardware Flow Control */
	if (C_CRTSCTS(tty)) {
#ifdef SPECIALIX_BRAIN_DAMAGED_CTS
		port->IER |= IER_DSR | IER_CTS;
		mcor1 |= MCOR1_DSRZD | MCOR1_CTSZD;
		mcor2 |= MCOR2_DSROD | MCOR2_CTSOD;
		tty->hw_stopped = !(sx_in(bp, CD186x_MSVR) & (MSVR_CTS|MSVR_DSR));
#else
		port->COR2 |= COR2_CTSAE; 
#endif
	}
	/* Enable Software Flow Control. FIXME: I'm not sure about this */
	/* Some people reported that it works, but I still doubt it */
	if (I_IXON(tty)) {
		port->COR2 |= COR2_TXIBE;
		cor3 |= (COR3_FCT | COR3_SCDE);
		if (I_IXANY(tty))
			port->COR2 |= COR2_IXM;
		sx_out(bp, CD186x_SCHR1, START_CHAR(tty));
		sx_out(bp, CD186x_SCHR2, STOP_CHAR(tty));
		sx_out(bp, CD186x_SCHR3, START_CHAR(tty));
		sx_out(bp, CD186x_SCHR4, STOP_CHAR(tty));
	}
	if (!C_CLOCAL(tty)) {
		/* Enable CD check */
		port->IER |= IER_CD;
		mcor1 |= MCOR1_CDZD;
		mcor2 |= MCOR2_CDOD;
	}
	
	if (C_CREAD(tty)) 
		/* Enable receiver */
		port->IER |= IER_RXD;
	
	/* Set input FIFO size (1-8 bytes) */
	cor3 |= SPECIALIX_RXFIFO; 
	/* Setting up CD186x channel registers */
	sx_out(bp, CD186x_COR1, cor1);
	sx_out(bp, CD186x_COR2, port->COR2);
	sx_out(bp, CD186x_COR3, cor3);
	/* Make CD186x know about registers change */
	sx_wait_CCR(bp);
	sx_out(bp, CD186x_CCR, CCR_CORCHG1 | CCR_CORCHG2 | CCR_CORCHG3);
	/* Setting up modem option registers */
#ifdef DEBUG_SPECIALIX
	printk ("Mcor1 = %02x, mcor2 = %02x.\n", mcor1, mcor2);
#endif
	sx_out(bp, CD186x_MCOR1, mcor1);
	sx_out(bp, CD186x_MCOR2, mcor2);
	/* Enable CD186x transmitter & receiver */
	sx_wait_CCR(bp);
	sx_out(bp, CD186x_CCR, CCR_TXEN | CCR_RXEN);
	/* Enable interrupts */
	sx_out(bp, CD186x_IER, port->IER);
	/* And finally set the modem lines... */
	sx_out(bp, CD186x_MSVR, port->MSVR);
}


/* Must be called with interrupts enabled */
static int sx_setup_port(struct specialix_board *bp, struct specialix_port *port)
{
	unsigned long flags;
	
	if (port->flags & ASYNC_INITIALIZED)
		return 0;
	
	if (!port->xmit_buf) {
		/* We may sleep in get_free_page() */
		unsigned long tmp;
		
		if (!(tmp = get_free_page(GFP_KERNEL)))
			return -ENOMEM;

		if (port->xmit_buf) {
			free_page(tmp);
			return -ERESTARTSYS;
		}
		port->xmit_buf = (unsigned char *) tmp;
	}
		
	save_flags(flags); cli();
		
	if (port->tty) 
		clear_bit(TTY_IO_ERROR, &port->tty->flags);
		
	if (port->count == 1) 
		bp->count++;
		
	port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
	sx_change_speed(bp, port);
	port->flags |= ASYNC_INITIALIZED;
		
	restore_flags(flags);
	return 0;
}


/* Must be called with interrupts disabled */
static void sx_shutdown_port(struct specialix_board *bp, struct specialix_port *port)
{
	struct tty_struct *tty;
	
	if (!(port->flags & ASYNC_INITIALIZED)) 
		return;
	
#ifdef SX_REPORT_OVERRUN
	printk(KERN_INFO "sx%d: port %d: Total %ld overruns were detected.\n",
	       board_No(bp), port_No(port), port->overrun);
#endif	
#ifdef SX_REPORT_FIFO
	{
		int i;
		
		printk(KERN_INFO "sx%d: port %d: FIFO hits [ ",
		       board_No(bp), port_No(port));
		for (i = 0; i < 10; i++) {
			printk("%ld ", port->hits[i]);
		}
		printk("].\n");
	}
#endif	
	if (port->xmit_buf) {
		free_page((unsigned long) port->xmit_buf);
		port->xmit_buf = NULL;
	}

	/* Select port */
	sx_out(bp, CD186x_CAR, port_No(port));

	if (!(tty = port->tty) || C_HUPCL(tty)) {
		/* Drop DTR */
		sx_out(bp, CD186x_MSVDTR, 0);
	}
	
	/* Reset port */
	sx_wait_CCR(bp);
	sx_out(bp, CD186x_CCR, CCR_SOFTRESET);
	/* Disable all interrupts from this port */
	port->IER = 0;
	sx_out(bp, CD186x_IER, port->IER);
	
	if (tty)
		set_bit(TTY_IO_ERROR, &tty->flags);
	port->flags &= ~ASYNC_INITIALIZED;
	
	if (--bp->count < 0) {
		printk(KERN_ERR "sx%d: sx_shutdown_port: bad board count: %d\n",
		       board_No(bp), bp->count);
		bp->count = 0;
	}
	
	/*
	 * If this is the last opened port on the board
	 * shutdown whole board
	 */
	if (!bp->count) 
		sx_shutdown_board(bp);
}

	
static int block_til_ready(struct tty_struct *tty, struct file * filp,
                           struct specialix_port *port)
{
	DECLARE_WAITQUEUE(wait,  current);
	struct specialix_board *bp = port_Board(port);
	int    retval;
	int    do_clocal = 0;
	int    CD;

	/*
	 * If the device is in the middle of being closed, then block
	 * until it's done, and then try again.
	 */
	if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
		interruptible_sleep_on(&port->close_wait);
		if (port->flags & ASYNC_HUP_NOTIFY)
			return -EAGAIN;
		else
			return -ERESTARTSYS;
	}

	/*
	 * If this is a callout device, then just make sure the normal
	 * device isn't being used.
	 */
	if (tty->driver.subtype == SPECIALIX_TYPE_CALLOUT) {
		if (port->flags & ASYNC_NORMAL_ACTIVE)
			return -EBUSY;
		if ((port->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (port->flags & ASYNC_SESSION_LOCKOUT) &&
		    (port->session != current->session))
			return -EBUSY;
		if ((port->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (port->flags & ASYNC_PGRP_LOCKOUT) &&
		    (port->pgrp != current->pgrp))
			return -EBUSY;
		port->flags |= ASYNC_CALLOUT_ACTIVE;
		return 0;
	}
	
	/*
	 * If non-blocking mode is set, or the port is not enabled,
	 * then make the check up front and then exit.
	 */
	if ((filp->f_flags & O_NONBLOCK) ||
	    (tty->flags & (1 << TTY_IO_ERROR))) {
		if (port->flags & ASYNC_CALLOUT_ACTIVE)
			return -EBUSY;
		port->flags |= ASYNC_NORMAL_ACTIVE;
		return 0;
	}

	if (port->flags & ASYNC_CALLOUT_ACTIVE) {
		if (port->normal_termios.c_cflag & CLOCAL) 
			do_clocal = 1;
	} else {
		if (C_CLOCAL(tty))
			do_clocal = 1;
	}
	
	/*
	 * Block waiting for the carrier detect and the line to become
	 * free (i.e., not in use by the callout).  While we are in
	 * this loop, info->count is dropped by one, so that
	 * rs_close() knows when to free things.  We restore it upon
	 * exit, either normal or abnormal.
	 */
	retval = 0;
	add_wait_queue(&port->open_wait, &wait);
	cli();
	if (!tty_hung_up_p(filp))
		port->count--;
	sti();
	port->blocked_open++;
	while (1) {
		cli();
		sx_out(bp, CD186x_CAR, port_No(port));
		CD = sx_in(bp, CD186x_MSVR) & MSVR_CD;
		if (!(port->flags & ASYNC_CALLOUT_ACTIVE)) {
			if (SX_CRTSCTS (tty)) {
				/* Activate RTS */
				port->MSVR |= MSVR_DTR;
				sx_out (bp, CD186x_MSVR, port->MSVR);
			} else {
				/* Activate DTR */
				port->MSVR |= MSVR_DTR;
				sx_out (bp, CD186x_MSVR, port->MSVR);
			} 
		}
		sti();
		set_current_state(TASK_INTERRUPTIBLE);
		if (tty_hung_up_p(filp) ||
		    !(port->flags & ASYNC_INITIALIZED)) {
			if (port->flags & ASYNC_HUP_NOTIFY)
				retval = -EAGAIN;
			else
				retval = -ERESTARTSYS;	
			break;
		}
		if (!(port->flags & ASYNC_CALLOUT_ACTIVE) &&
		    !(port->flags & ASYNC_CLOSING) &&
		    (do_clocal || CD))
			break;
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
		schedule();
	}
	current->state = TASK_RUNNING;
	remove_wait_queue(&port->open_wait, &wait);
	if (!tty_hung_up_p(filp))
		port->count++;
	port->blocked_open--;
	if (retval)
		return retval;
	
	port->flags |= ASYNC_NORMAL_ACTIVE;
	return 0;
}	


static int sx_open(struct tty_struct * tty, struct file * filp)
{
	int board;
	int error;
	struct specialix_port * port;
	struct specialix_board * bp;