su.c

自己根据lkd和情境分析

		if (--info->xmit_cnt <= 0)
			break;
	} while (--count > 0);
	
	if (info->xmit_cnt < WAKEUP_CHARS)
		su_sched_event(info, RS_EVENT_WRITE_WAKEUP);

#ifdef SERIAL_DEBUG_INTR
	printk("T%d...", info->xmit_cnt);
#endif
	if (intr_done)
		*intr_done = 0;

	if (info->xmit_cnt <= 0) {
		info->IER &= ~UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
	}
}

static void
check_modem_status(struct su_struct *info)
{
	int	status;
	struct	async_icount *icount;

	status = serial_in(info, UART_MSR);

	if (status & UART_MSR_ANY_DELTA) {
		icount = &info->icount;
		/* update input line counters */
		if (status & UART_MSR_TERI)
			icount->rng++;
		if (status & UART_MSR_DDSR)
			icount->dsr++;
		if (status & UART_MSR_DDCD) {
			icount->dcd++;
#ifdef CONFIG_HARD_PPS
			if ((info->flags & ASYNC_HARDPPS_CD) &&
			    (status & UART_MSR_DCD))
				hardpps();
#endif
		}
		if (status & UART_MSR_DCTS)
			icount->cts++;
		wake_up_interruptible(&info->delta_msr_wait);
	}

	if ((info->flags & ASYNC_CHECK_CD) && (status & UART_MSR_DDCD)) {
#if (defined(SERIAL_DEBUG_OPEN) || defined(SERIAL_DEBUG_INTR))
		printk("ttys%d CD now %s...", info->line,
		       (status & UART_MSR_DCD) ? "on" : "off");
#endif		
		if (status & UART_MSR_DCD)
			wake_up_interruptible(&info->open_wait);
		else if (!((info->flags & ASYNC_CALLOUT_ACTIVE) &&
			   (info->flags & ASYNC_CALLOUT_NOHUP))) {
#ifdef SERIAL_DEBUG_OPEN
			printk("doing serial hangup...");
#endif
			if (info->tty)
				tty_hangup(info->tty);
	}
	}
	if (info->flags & ASYNC_CTS_FLOW) {
		if (info->tty->hw_stopped) {
			if (status & UART_MSR_CTS) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx start...");
#endif
				info->tty->hw_stopped = 0;
				info->IER |= UART_IER_THRI;
				serial_out(info, UART_IER, info->IER);
				su_sched_event(info, RS_EVENT_WRITE_WAKEUP);
				return;
			}
		} else {
			if (!(status & UART_MSR_CTS)) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx stop...");
#endif
				info->tty->hw_stopped = 1;
				info->IER &= ~UART_IER_THRI;
				serial_out(info, UART_IER, info->IER);
			}
		}
	}
}

/*
 * This is the kbd/mouse serial driver's interrupt routine
 */
static void
su_kbd_ms_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	struct su_struct *info = (struct su_struct *)dev_id;
	unsigned char status;

#ifdef SERIAL_DEBUG_INTR
	printk("su_kbd_ms_interrupt(%s)...", __irq_itoa(irq));
#endif
	if (!info)
		return;

	if (serial_in(info, UART_IIR) & UART_IIR_NO_INT)
		return;

	status = serial_inp(info, UART_LSR);
#ifdef SERIAL_DEBUG_INTR
	printk("status = %x...", status);
#endif
	if ((status & UART_LSR_DR) || (status & UART_LSR_BI))
		receive_kbd_ms_chars(info, regs,
				     (status & UART_LSR_BI) != 0);

#ifdef SERIAL_DEBUG_INTR
	printk("end.\n");
#endif
}

/*
 * This is the serial driver's generic interrupt routine
 */
static void
su_serial_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	int status;
	struct su_struct *info;
	int pass_counter = 0;

#ifdef SERIAL_DEBUG_INTR
	printk("su_serial_interrupt(%s)...", __irq_itoa(irq));
#endif
	info = (struct su_struct *)dev_id;
	if (!info || !info->tty) {
#ifdef SERIAL_DEBUG_INTR
		printk("strain\n");
#endif
		return;
	}

	do {
		status = serial_inp(info, UART_LSR);
#ifdef SERIAL_DEBUG_INTR
		printk("status = %x...", status);
#endif
		if (status & UART_LSR_DR)
			receive_serial_chars(info, &status, regs);
		check_modem_status(info);
		if (status & UART_LSR_THRE)
			transmit_chars(info, 0);

		if (pass_counter++ > RS_ISR_PASS_LIMIT) {
#ifdef SERIAL_DEBUG_INTR
			printk("rs loop break");
#endif
			break; 	/* Prevent infinite loops */
		}
	} while (!(serial_in(info, UART_IIR) & UART_IIR_NO_INT));

	info->last_active = jiffies;

#ifdef SERIAL_DEBUG_INTR
	printk("end.\n");
#endif
}

/*
 * -------------------------------------------------------------------
 * Here ends the serial interrupt routines.
 * -------------------------------------------------------------------
 */

/*
 * This routine is used to handle the "bottom half" processing for the
 * serial driver, known also the "software interrupt" processing.
 * This processing is done at the kernel interrupt level, after the
 * su_interrupt() has returned, BUT WITH INTERRUPTS TURNED ON.  This
 * is where time-consuming activities which can not be done in the
 * interrupt driver proper are done; the interrupt driver schedules
 * them using su_sched_event(), and they get done here.
 */
static void do_serial_bh(void)
{
	run_task_queue(&tq_serial);
}

static void do_softint(void *private_)
{
	struct su_struct	*info = (struct su_struct *) private_;
	struct tty_struct	*tty;

	tty = info->tty;
	if (!tty)
		return;

	if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &info->event)) {
		if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
		    tty->ldisc.write_wakeup)
			(tty->ldisc.write_wakeup)(tty);
		wake_up_interruptible(&tty->write_wait);
	}
}

/*
 * ---------------------------------------------------------------
 * Low level utility subroutines for the serial driver:  routines to
 * figure out the appropriate timeout for an interrupt chain, routines
 * to initialize and startup a serial port, and routines to shutdown a
 * serial port.  Useful stuff like that.
 * ---------------------------------------------------------------
 */

static int
startup(struct su_struct *info)
{
	unsigned long flags;
	int	retval=0;
	unsigned long page;

	save_flags(flags);
	if (info->tty) {
		page = get_free_page(GFP_KERNEL);
		if (!page)
			return -ENOMEM;

		cli();

		if (info->flags & ASYNC_INITIALIZED) {
			free_page(page);
			goto errout;
		}

		if (info->port == 0 || info->type == PORT_UNKNOWN) {
			set_bit(TTY_IO_ERROR, &info->tty->flags);
			free_page(page);
			goto errout;
		}
		if (info->xmit_buf)
			free_page(page);
		else
			info->xmit_buf = (unsigned char *) page;
	}
	cli();

#ifdef SERIAL_DEBUG_OPEN
	printk("starting up ttys%d (irq %s)...", info->line,
	       __irq_itoa(info->irq));
#endif

	if (uart_config[info->type].flags & UART_STARTECH) {
		/* Wake up UART */
		serial_outp(info, UART_LCR, 0xBF);
		serial_outp(info, UART_EFR, UART_EFR_ECB);
		serial_outp(info, UART_IER, 0);
		serial_outp(info, UART_EFR, 0);
		serial_outp(info, UART_LCR, 0);
	}

	if (info->type == PORT_16750) {
		/* Wake up UART */
		serial_outp(info, UART_IER, 0);
	}

	/*
	 * Clear the FIFO buffers and disable them
	 * (they will be reenabled in change_speed())
	 */
	if (uart_config[info->type].flags & UART_CLEAR_FIFO)
		serial_outp(info, UART_FCR, (UART_FCR_CLEAR_RCVR |
					     UART_FCR_CLEAR_XMIT));

	/*
	 * At this point there's no way the LSR could still be 0xFF;
	 * if it is, then bail out, because there's likely no UART
	 * here.
	 */
	if (serial_inp(info, UART_LSR) == 0xff) {
		if (capable(CAP_SYS_ADMIN)) {
			if (info->tty)
				set_bit(TTY_IO_ERROR, &info->tty->flags);
		} else
			retval = -ENODEV;
		goto errout;
	}

	/*
	 * Allocate the IRQ if necessary
	 */
	if (info->port_type != SU_PORT_PORT) {
		retval = request_irq(info->irq, su_kbd_ms_interrupt,
				     SA_SHIRQ, info->name, info);
	} else {
		retval = request_irq(info->irq, su_serial_interrupt,
				     SA_SHIRQ, info->name, info);
	}
	if (retval) {
		if (capable(CAP_SYS_ADMIN)) {
			if (info->tty)
				set_bit(TTY_IO_ERROR, &info->tty->flags);
			retval = 0;
		}
		goto errout;
	}

	/*
	 * Clear the interrupt registers.
	 */
	(void) serial_inp(info, UART_RX);
	(void) serial_inp(info, UART_IIR);
	(void) serial_inp(info, UART_MSR);

	/*
	 * Now, initialize the UART 
	 */
	serial_outp(info, UART_LCR, UART_LCR_WLEN8);	/* reset DLAB */

	info->MCR = 0;
	if (info->tty && info->tty->termios->c_cflag & CBAUD)
		info->MCR = UART_MCR_DTR | UART_MCR_RTS;
	if (info->irq != 0)
		info->MCR |= UART_MCR_OUT2;
	serial_outp(info, UART_MCR, info->MCR);

	/*
	 * Finally, enable interrupts
	 */
	info->IER = UART_IER_MSI | UART_IER_RLSI | UART_IER_RDI;
	serial_outp(info, UART_IER, info->IER);	/* enable interrupts */

	/*
	 * And clear the interrupt registers again for luck.
	 */
	(void)serial_inp(info, UART_LSR);
	(void)serial_inp(info, UART_RX);
	(void)serial_inp(info, UART_IIR);
	(void)serial_inp(info, UART_MSR);

	if (info->tty)
		clear_bit(TTY_IO_ERROR, &info->tty->flags);
	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

	/*
	 * Set up the tty->alt_speed kludge
	 */
	if (info->tty) {
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
			info->tty->alt_speed = 57600;
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
			info->tty->alt_speed = 115200;
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
			info->tty->alt_speed = 230400;
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
			info->tty->alt_speed = 460800;
	}

	/*
	 * and set the speed of the serial port
	 */
	change_speed(info, 0);

	info->flags |= ASYNC_INITIALIZED;
	restore_flags(flags);
	return 0;

errout:
	restore_flags(flags);
	return retval;
}

/*
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 */
static void
shutdown(struct su_struct *info)
{
	unsigned long	flags;

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

	save_flags(flags); cli(); /* Disable interrupts */

	/*
	 * clear delta_msr_wait queue to avoid mem leaks: we may free the irq
	 * here so the queue might never be waken up
	 */
	wake_up_interruptible(&info->delta_msr_wait);
	
	/*
	 * Free the IRQ, if necessary
	 */
	free_irq(info->irq, info);

	if (info->xmit_buf) {
		free_page((unsigned long) info->xmit_buf);
		info->xmit_buf = 0;
	}

	info->IER = 0;
	serial_outp(info, UART_IER, 0x00);	/* disable all intrs */
	info->MCR &= ~UART_MCR_OUT2;

	/* disable break condition */
	serial_out(info, UART_LCR, serial_inp(info, UART_LCR) & ~UART_LCR_SBC);

	if (!info->tty || (info->tty->termios->c_cflag & HUPCL))
		info->MCR &= ~(UART_MCR_DTR|UART_MCR_RTS);
	serial_outp(info, UART_MCR, info->MCR);

	/* disable FIFO's */	
	serial_outp(info, UART_FCR, (UART_FCR_CLEAR_RCVR |
				     UART_FCR_CLEAR_XMIT));
	(void)serial_in(info, UART_RX);    /* read data port to reset things */

	if (info->tty)
		set_bit(TTY_IO_ERROR, &info->tty->flags);

	if (uart_config[info->type].flags & UART_STARTECH) {
		/* Arrange to enter sleep mode */
		serial_outp(info, UART_LCR, 0xBF);
		serial_outp(info, UART_EFR, UART_EFR_ECB);
		serial_outp(info, UART_IER, UART_IERX_SLEEP);
		serial_outp(info, UART_LCR, 0);
	}
	if (info->type == PORT_16750) {
		/* Arrange to enter sleep mode */
		serial_outp(info, UART_IER, UART_IERX_SLEEP);
	}
	info->flags &= ~ASYNC_INITIALIZED;
	restore_flags(flags);
}

static int
su_get_baud_rate(struct su_struct *info)
{
	static struct tty_struct c_tty;
	static struct termios c_termios;

	if (info->tty)
		return tty_get_baud_rate(info->tty);

	memset(&c_tty, 0, sizeof(c_tty));
	memset(&c_termios, 0, sizeof(c_termios));
	c_tty.termios = &c_termios;
	c_termios.c_cflag = info->cflag;

	return tty_get_baud_rate(&c_tty);
}

/*
 * This routine is called to set the UART divisor registers to match
 * the specified baud rate for a serial port.
 */
static void
change_speed(struct su_struct *info,
	     struct termios *old_termios)
{
	int		quot = 0, baud;
	unsigned int	cval, fcr = 0;
	int		bits;
	unsigned long	flags;

	if (info->port_type == SU_PORT_PORT) {
		if (!info->tty || !info->tty->termios)
			return;
		if (!info->port)
			return;
		info->cflag = info->tty->termios->c_cflag;
	}

	/* byte size and parity */
	switch (info->cflag & CSIZE) {
	      case CS5: cval = 0x00; bits = 7; break;
	      case CS6: cval = 0x01; bits = 8; break;
	      case CS7: cval = 0x02; bits = 9; break;
	      case CS8: cval = 0x03; bits = 10; break;
		/* Never happens, but GCC is too dumb to figure it out */
	      default:  cval = 0x00; bits = 7; break;
	}
	if (info->cflag & CSTOPB) {
		cval |= 0x04;
		bits++;
	}
	if (info->cflag & PARENB) {
		cval |= UART_LCR_PARITY;
		bits++;
	}
	if (!(info->cflag & PARODD))
		cval |= UART_LCR_EPAR;
#ifdef CMSPAR
	if (info->cflag & CMSPAR)
		cval |= UART_LCR_SPAR;
#endif

	/* Determine divisor based on baud rate */
	baud = su_get_baud_rate(info);
	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);