su.c

自己根据lkd和情境分析

		else if (baud)
			quot = info->baud_base / baud;
	}
	/* If the quotient is zero refuse the change */
	if (!quot && old_termios) {
		info->tty->termios->c_cflag &= ~CBAUD;
		info->tty->termios->c_cflag |= (old_termios->c_cflag & CBAUD);
		baud = tty_get_baud_rate(info->tty);
		if (!baud)
			baud = 9600;
		if (baud == 38400 &&
		    ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST))
			quot = info->custom_divisor;
		else {
			if (baud == 134)
				/* Special case since 134 is really 134.5 */
				quot = (2*info->baud_base / 269);
			else if (baud)
				quot = info->baud_base / baud;
		}
	}
	/* As a last resort, if the quotient is zero, default to 9600 bps */
	if (!quot)
		quot = info->baud_base / 9600;
	info->timeout = ((info->xmit_fifo_size*HZ*bits*quot) / info->baud_base);
	info->timeout += HZ/50;		/* Add .02 seconds of slop */

	/* Set up FIFO's */
	if (uart_config[info->type].flags & UART_USE_FIFO) {
		if ((info->baud_base / quot) < 9600)
			fcr = UART_FCR_ENABLE_FIFO | UART_FCR_TRIGGER_1;
		else
			fcr = UART_FCR_ENABLE_FIFO | UART_FCR_TRIGGER_8;
	}
	if (info->type == PORT_16750)
		fcr |= UART_FCR7_64BYTE;

	/* CTS flow control flag and modem status interrupts */
	info->IER &= ~UART_IER_MSI;
	if (info->flags & ASYNC_HARDPPS_CD)
		info->IER |= UART_IER_MSI;
	if (info->cflag & CRTSCTS) {
		info->flags |= ASYNC_CTS_FLOW;
		info->IER |= UART_IER_MSI;
	} else
		info->flags &= ~ASYNC_CTS_FLOW;
	if (info->cflag & CLOCAL)
		info->flags &= ~ASYNC_CHECK_CD;
	else {
		info->flags |= ASYNC_CHECK_CD;
		info->IER |= UART_IER_MSI;
	}
	serial_out(info, UART_IER, info->IER);

	/*
	 * Set up parity check flag
	 */
	if (info->tty) {
#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

		info->read_status_mask = UART_LSR_OE | UART_LSR_THRE |
					 UART_LSR_DR;
		if (I_INPCK(info->tty))
			info->read_status_mask |= UART_LSR_FE | UART_LSR_PE;
		if (I_BRKINT(info->tty) || I_PARMRK(info->tty))
			info->read_status_mask |= UART_LSR_BI;

		/*
		 * Characters to ignore
		 */
		info->ignore_status_mask = 0;
		if (I_IGNPAR(info->tty))
			info->ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
		if (I_IGNBRK(info->tty)) {
			info->ignore_status_mask |= UART_LSR_BI;
			/*
			 * If we're ignore parity and break indicators, ignore 
			 * overruns too.  (For real raw support).
			 */
			if (I_IGNPAR(info->tty))
				info->ignore_status_mask |= UART_LSR_OE;
		}
		/*
		 * !!! ignore all characters if CREAD is not set
		 */
		if ((info->cflag & CREAD) == 0)
			info->ignore_status_mask |= UART_LSR_DR;
	}

	save_flags(flags); cli();
	if (uart_config[info->type].flags & UART_STARTECH) {
		serial_outp(info, UART_LCR, 0xBF);
		serial_outp(info, UART_EFR,
			    (info->cflag & CRTSCTS) ? UART_EFR_CTS : 0);
	}
	serial_outp(info, UART_LCR, cval | UART_LCR_DLAB);	/* set DLAB */
	serial_outp(info, UART_DLL, quot & 0xff);	/* LS of divisor */
	serial_outp(info, UART_DLM, quot >> 8);		/* MS of divisor */
	if (info->type == PORT_16750)
		serial_outp(info, UART_FCR, fcr); 	/* set fcr */
	serial_outp(info, UART_LCR, cval);		/* reset DLAB */
	if (info->type != PORT_16750)
		serial_outp(info, UART_FCR, fcr); 	/* set fcr */
	restore_flags(flags);
	info->quot = quot;
}

static void
su_put_char(struct tty_struct *tty, unsigned char ch)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "su_put_char"))
		return;

	if (!tty || !info->xmit_buf)
		return;

	save_flags(flags); cli();
	if (info->xmit_cnt >= SERIAL_XMIT_SIZE - 1) {
		restore_flags(flags);
		return;
	}

	info->xmit_buf[info->xmit_head++] = ch;
	info->xmit_head &= SERIAL_XMIT_SIZE-1;
	info->xmit_cnt++;
	restore_flags(flags);
}

static void su_put_char_kbd(unsigned char c)
{
	struct su_struct *info = su_table;
	int lsr;

	if (info->port_type != SU_PORT_KBD)
		++info;
	if (info->port_type != SU_PORT_KBD)
		return;

	do {
		lsr = serial_in(info, UART_LSR);
	} while (!(lsr & UART_LSR_THRE));

	/* Send the character out. */
	su_outb(info, UART_TX, c);
}

static void
su_change_mouse_baud(int baud)
{
	struct su_struct *info = su_table;

	if (info->port_type != SU_PORT_MS)
		++info;
	if (info->port_type != SU_PORT_MS)
		return;

	info->cflag &= ~CBAUD;
	switch (baud) {
		case 1200:
			info->cflag |= B1200;
			break;
		case 2400:
			info->cflag |= B2400;
			break;
		case 4800:
			info->cflag |= B4800;
			break;
		case 9600:
			info->cflag |= B9600;
			break;
		default:
			printk("su_change_mouse_baud: unknown baud rate %d, "
			       "defaulting to 1200\n", baud);
			info->cflag |= 1200;
			break;
	}
	change_speed(info, 0);
}

static void
su_flush_chars(struct tty_struct *tty)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;
	unsigned long flags;
				
	if (serial_paranoia_check(info, tty->device, "su_flush_chars"))
		return;

	if (info->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped ||
	    !info->xmit_buf)
		return;

	save_flags(flags); cli();
	info->IER |= UART_IER_THRI;
	serial_out(info, UART_IER, info->IER);
	restore_flags(flags);
}

static int
su_write(struct tty_struct * tty, int from_user,
		    const unsigned char *buf, int count)
{
	int	c, ret = 0;
	struct su_struct *info = (struct su_struct *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "su_write"))
		return 0;

	if (!tty || !info->xmit_buf || !tmp_buf)
		return 0;

	save_flags(flags);
	if (from_user) {
		down(&tmp_buf_sem);
		while (1) {
			c = MIN(count,
				MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
				    SERIAL_XMIT_SIZE - info->xmit_head));
			if (c <= 0)
				break;

			c -= copy_from_user(tmp_buf, buf, c);
			if (!c) {
				if (!ret)
					ret = -EFAULT;
				break;
			}
			cli();
			c = MIN(c, MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
				       SERIAL_XMIT_SIZE - info->xmit_head));
			memcpy(info->xmit_buf + info->xmit_head, tmp_buf, c);
			info->xmit_head = ((info->xmit_head + c) &
					   (SERIAL_XMIT_SIZE-1));
			info->xmit_cnt += c;
			restore_flags(flags);
			buf += c;
			count -= c;
			ret += c;
		}
		up(&tmp_buf_sem);
	} else {
		while (1) {
			cli();		
			c = MIN(count,
				MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
				    SERIAL_XMIT_SIZE - info->xmit_head));
			if (c <= 0) {
				restore_flags(flags);
				break;
			}
			memcpy(info->xmit_buf + info->xmit_head, buf, c);
			info->xmit_head = ((info->xmit_head + c) &
					   (SERIAL_XMIT_SIZE-1));
			info->xmit_cnt += c;
			restore_flags(flags);
			buf += c;
			count -= c;
			ret += c;
		}
	}
	if (info->xmit_cnt && !tty->stopped && !tty->hw_stopped &&
	    !(info->IER & UART_IER_THRI)) {
		info->IER |= UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
	}
	return ret;
}

static int
su_write_room(struct tty_struct *tty)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;
	int	ret;

	if (serial_paranoia_check(info, tty->device, "su_write_room"))
		return 0;
	ret = SERIAL_XMIT_SIZE - info->xmit_cnt - 1;
	if (ret < 0)
		ret = 0;
	return ret;
}

static int
su_chars_in_buffer(struct tty_struct *tty)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;
				
	if (serial_paranoia_check(info, tty->device, "su_chars_in_buffer"))
		return 0;
	return info->xmit_cnt;
}

static void
su_flush_buffer(struct tty_struct *tty)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "su_flush_buffer"))
		return;
	save_flags(flags); cli();
	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
	restore_flags(flags);
	wake_up_interruptible(&tty->write_wait);
	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
	    tty->ldisc.write_wakeup)
		(tty->ldisc.write_wakeup)(tty);
}

/*
 * This function is used to send a high-priority XON/XOFF character to
 * the device
 */
static void
su_send_xchar(struct tty_struct *tty, char ch)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;

	if (serial_paranoia_check(info, tty->device, "su_send_char"))
		return;

	if (!(info->flags & ASYNC_INITIALIZED))
		return;

	info->x_char = ch;
	if (ch) {
		/* Make sure transmit interrupts are on */
		info->IER |= UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
	}
}

/*
 * ------------------------------------------------------------
 * su_throttle()
 * 
 * This routine is called by the upper-layer tty layer to signal that
 * incoming characters should be throttled.
 * ------------------------------------------------------------
 */
static void
su_throttle(struct tty_struct * tty)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;
	unsigned long flags;
#ifdef SERIAL_DEBUG_THROTTLE
	char	buf[64];

	printk("throttle %s: %d....\n", tty_name(tty, buf),
	       tty->ldisc.chars_in_buffer(tty));
#endif

	if (serial_paranoia_check(info, tty->device, "su_throttle"))
		return;

	if (I_IXOFF(tty))
		su_send_xchar(tty, STOP_CHAR(tty));

	if (tty->termios->c_cflag & CRTSCTS)
		info->MCR &= ~UART_MCR_RTS;

	save_flags(flags); cli();
	serial_out(info, UART_MCR, info->MCR);
	restore_flags(flags);
}

static void
su_unthrottle(struct tty_struct * tty)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;
	unsigned long flags;
#ifdef SERIAL_DEBUG_THROTTLE
	char	buf[64];

	printk("unthrottle %s: %d....\n", tty_name(tty, buf),
	       tty->ldisc.chars_in_buffer(tty));
#endif

	if (serial_paranoia_check(info, tty->device, "su_unthrottle"))
		return;

	if (I_IXOFF(tty)) {
		if (info->x_char)
			info->x_char = 0;
		else
			su_send_xchar(tty, START_CHAR(tty));
	}
	if (tty->termios->c_cflag & CRTSCTS)
		info->MCR |= UART_MCR_RTS;
	save_flags(flags); cli();
	serial_out(info, UART_MCR, info->MCR);
	restore_flags(flags);
}

/*
 * ------------------------------------------------------------
 * su_ioctl() and friends
 * ------------------------------------------------------------
 */

/*
 * get_serial_info - handle TIOCGSERIAL ioctl()
 *
 * Purpose: Return standard serial struct information about
 *          a serial port handled by this driver.
 *
 * Added:   11-May-2001 Lars Kellogg-Stedman <[e-mail]>
 */
static int get_serial_info(struct su_struct * info,
			   struct serial_struct * retinfo)
{
	struct serial_struct	tmp;

	if (!retinfo)
		return -EFAULT;
	memset(&tmp, 0, sizeof(tmp));

	tmp.type		= info->type;
	tmp.line		= info->line;
	tmp.port		= info->port;
	tmp.irq			= info->irq;
	tmp.flags		= info->flags;
	tmp.xmit_fifo_size	= info->xmit_fifo_size;
	tmp.baud_base		= info->baud_base;
	tmp.close_delay		= info->close_delay;
	tmp.closing_wait	= info->closing_wait;
	tmp.custom_divisor	= info->custom_divisor;
	tmp.hub6		= 0;

	if (copy_to_user(retinfo,&tmp,sizeof(*retinfo)))
		return -EFAULT;

	return 0;
}

/*
 * get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 * 	    is emptied.  On bus types like RS485, the transmitter must
 * 	    release the bus after transmitting. This must be done when
 * 	    the transmit shift register is empty, not be done when the
 * 	    transmit holding register is empty.  This functionality
 * 	    allows an RS485 driver to be written in user space. 
 */
static int
get_lsr_info(struct su_struct * info, unsigned int *value)
{
	unsigned char status;
	unsigned int result;
	unsigned long flags;

	save_flags(flags); cli();
	status = serial_in(info, UART_LSR);
	restore_flags(flags);
	result = ((status & UART_LSR_TEMT) ? TIOCSER_TEMT : 0);
	return put_user(result,value);
}


static int
get_modem_info(struct su_struct * info, unsigned int *value)
{
	unsigned char control, status;
	unsigned int result;
	unsigned long flags;

	control = info->MCR;
	save_flags(flags); cli();
	status = serial_in(info, UART_MSR);
	restore_flags(flags);
	result =  ((control & UART_MCR_RTS) ? TIOCM_RTS : 0)
		| ((control & UART_MCR_DTR) ? TIOCM_DTR : 0)
#ifdef TIOCM_OUT1
		| ((control & UART_MCR_OUT1) ? TIOCM_OUT1 : 0)
		| ((control & UART_MCR_OUT2) ? TIOCM_OUT2 : 0)
#endif
		| ((status  & UART_MSR_DCD) ? TIOCM_CAR : 0)
		| ((status  & UART_MSR_RI) ? TIOCM_RNG : 0)
		| ((status  & UART_MSR_DSR) ? TIOCM_DSR : 0)
		| ((status  & UART_MSR_CTS) ? TIOCM_CTS : 0);
	return put_user(result,value);
}

static int
set_modem_info(struct su_struct * info, unsigned int cmd, unsigned int *value)
{
	unsigned int arg;
	unsigned long flags;

	if (get_user(arg, value))
		return -EFAULT;
	switch (cmd) {
	case TIOCMBIS: 
		if (arg & TIOCM_RTS)
			info->MCR |= UART_MCR_RTS;
		if (arg & TIOCM_DTR)
			info->MCR |= UART_MCR_DTR;
#ifdef TIOCM_OUT1
		if (arg & TIOCM_OUT1)