serial.c

上传linux-jx2410的源代码

		serial_out(info, UART_IER, info->IER);
	}
}

static _INLINE_ void check_modem_status(struct async_struct *info)
{
	int	status;
	struct	async_icount *icount;
	
	status = serial_in(info, UART_MSR);

	if (status & UART_MSR_ANY_DELTA) {
		icount = &info->state->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);
				rs_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 serial driver's interrupt routine for a single port
 */
static void rs_interrupt_single(int irq, void *dev_id, struct pt_regs * regs)
{
	int status;
	int pass_counter = 0;
	struct async_struct * info;
	
#ifdef SERIAL_DEBUG_INTR
	printk("rs_interrupt_single(%d)...", irq);
#endif

	info = IRQ_ports[irq];
	if (!info || !info->tty)
		return;

	do {
		status = serial_inp(info, UART_LSR);
#ifdef SERIAL_DEBUG_INTR
		printk("status = %x...", status);
#endif
		if (status & UART_LSR_DR)
			receive_chars(info, &status, regs);
		check_modem_status(info);
		if (status & UART_LSR_THRE)
			transmit_chars(info, 0);
		if (pass_counter++ > RS_ISR_PASS_LIMIT) {
#if 0
			printk("rs_single loop break.\n");
#endif
			break;
		}
	} 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
 * rs_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 rs_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 async_struct	*info = (struct async_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);
#ifdef SERIAL_HAVE_POLL_WAIT
		wake_up_interruptible(&tty->poll_wait);
#endif
	}
}

/*
 * This subroutine is called when the RS_TIMER goes off.  It is used
 * by the serial driver to handle ports that do not have an interrupt
 * (irq=0).  This doesn't work very well for 16450's, but gives barely
 * passable results for a 16550A.  (Although at the expense of much
 * CPU overhead).
 */
static void rs_timer(unsigned long dummy)
{
	static unsigned long last_strobe;
	struct async_struct *info;
	unsigned int	i;
	unsigned long flags;

	if ((jiffies - last_strobe) >= RS_STROBE_TIME) {
		for (i=0; i < NR_IRQS; i++) {
			info = IRQ_ports[i];
			if (!info)
				continue;
			save_flags(flags); cli();
				rs_interrupt_single(i, NULL, NULL);
			restore_flags(flags);
		}
	}
	last_strobe = jiffies;
	mod_timer(&serial_timer, jiffies + RS_STROBE_TIME);

#if 0
	if (IRQ_ports[0]) {
		save_flags(flags); cli();
		rs_interrupt_single(0, NULL, NULL);
		restore_flags(flags);

		mod_timer(&serial_timer, jiffies + IRQ_timeout[0]);
	}
#endif
}

/*
 * ---------------------------------------------------------------
 * 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.
 * ---------------------------------------------------------------
 */

/*
 * This routine figures out the correct timeout for a particular IRQ.
 * It uses the smallest timeout of all of the serial ports in a
 * particular interrupt chain.  Now only used for IRQ 0....
 */
static void figure_IRQ_timeout(int irq)
{
	struct	async_struct	*info;
	int	timeout = 60*HZ;	/* 60 seconds === a long time :-) */

	info = IRQ_ports[irq];
	if (!info) {
		IRQ_timeout[irq] = 60*HZ;
		return;
	}
	while (info) {
		if (info->timeout < timeout)
			timeout = info->timeout;
		info = info->next_port;
	}
	if (!irq)
		timeout = timeout / 2;
	IRQ_timeout[irq] = (timeout > 3) ? timeout-2 : 1;
}


static int startup(struct async_struct * info)
{
	unsigned long flags;
	int	retval=0;
	void (*handler)(int, void *, struct pt_regs *);
	struct serial_state *state= info->state;
	unsigned long page;

	page = get_zeroed_page(GFP_KERNEL);
	if (!page)
		return -ENOMEM;

	save_flags(flags); cli();

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

	if (!CONFIGURED_SERIAL_PORT(state) || !state->type) {
		if (info->tty)
			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;


	if (inl(UART_MOD_CNTRL + state->port) != 0x3) {
		outl(3, UART_MOD_CNTRL + state->port);
	}
#ifdef SERIAL_DEBUG_OPEN
	printk("starting up ttys%d (irq %d)...", info->line, state->irq);
#endif


	/*
	 * Clear the FIFO buffers and disable them
	 * (they will be reenabled in change_speed())
	 */
	if (uart_config[state->type].flags & UART_CLEAR_FIFO) {
		serial_outp(info, UART_FCR, UART_FCR_ENABLE_FIFO);
		serial_outp(info, UART_FCR, (UART_FCR_ENABLE_FIFO |
					     UART_FCR_CLEAR_RCVR |
					     UART_FCR_CLEAR_XMIT));
		serial_outp(info, UART_FCR, 0);
	}

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

	/*
	 * 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 (!(info->flags & ASYNC_BUGGY_UART) &&
	    (serial_inp(info, UART_LSR) == 0xff)) {
		printk("LSR safety check engaged!\n");
		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 0
	/* au1000, uart0 irq is 0 */
	if (state->irq && (!IRQ_ports[state->irq] || !IRQ_ports[state->irq]->next_port)) {
#endif
	if ((!IRQ_ports[state->irq] || !IRQ_ports[state->irq]->next_port)) {
		if (IRQ_ports[state->irq]) {
			retval = -EBUSY;
			goto errout;
		} else 
			handler = rs_interrupt_single;

		retval = request_irq(state->irq, handler, SA_SHIRQ,
				     "serial", &IRQ_ports[state->irq]);
		if (retval) {
			if (capable(CAP_SYS_ADMIN)) {
				if (info->tty)
					set_bit(TTY_IO_ERROR,
						&info->tty->flags);
				retval = 0;
			}
			goto errout;
		}
	}

	/*
	 * Insert serial port into IRQ chain.
	 */
	info->prev_port = 0;
	info->next_port = IRQ_ports[state->irq];
	if (info->next_port)
		info->next_port->prev_port = info;
	IRQ_ports[state->irq] = info;
	figure_IRQ_timeout(state->irq);

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

	info->MCR = 0;
	if (info->tty->termios->c_cflag & CBAUD)
		info->MCR = UART_MCR_DTR | UART_MCR_RTS;
	{
		if (state->irq != 0)
			info->MCR |= UART_MCR_OUT2;
	}
	info->MCR |= ALPHA_KLUDGE_MCR; 		/* Don't ask */
	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.head = info->xmit.tail = 0;

	/*
	 * Set up serial timers...
	 */
	mod_timer(&serial_timer, jiffies + 2*HZ/100);

	/*
	 * 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 async_struct * info)
{
	unsigned long	flags;
	struct serial_state *state;
	int		retval;

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

	state = info->state;

#ifdef SERIAL_DEBUG_OPEN
	printk("Shutting down serial port %d (irq %d)....", info->line,
	       state->irq);
#endif
	
	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);
	
	/*
	 * First unlink the serial port from the IRQ chain...
	 */
	if (info->next_port)
		info->next_port->prev_port = info->prev_port;
	if (info->prev_port)
		info->prev_port->next_port = info->next_port;
	else
		IRQ_ports[state->irq] = info->next_port;
	figure_IRQ_timeout(state->irq);
	
	/*
	 * Free the IRQ, if necessary
	 */
//	if (state->irq && (!IRQ_ports[state->irq] ||
	if ((!IRQ_ports[state->irq] ||
			  !IRQ_ports[state->irq]->next_port)) {
		if (IRQ_ports[state->irq]) {
			free_irq(state->irq, &IRQ_ports[state->irq]);
			retval = request_irq(state->irq, rs_interrupt_single,
					     SA_SHIRQ, "serial",
					     &IRQ_ports[state->irq]);
			
			if (retval)
				printk("serial shutdown: request_irq: error %d"
				       "  Couldn't reacquire IRQ.\n", retval);
		} else
			free_irq(state->irq, &IRQ_ports[state->irq]);
	}

	if (info->xmit.buf) {
		unsigned long pg = (unsigned long) info->xmit.buf;
		info->xmit.buf = 0;
		free_page(pg);
	}

	info->IER = 0;
	serial_outp(info, UART_IER, 0x00);	/* disable all intrs */
		info->MCR &= ~UART_MCR_OUT2;
	info->MCR |= ALPHA_KLUDGE_MCR; 		/* Don't ask */
	
	/* 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_ENABLE_FIFO |
				     UART_FCR_CLEAR_RCVR |
				     UART_FCR_CLEAR_XMIT));
	serial_outp(info, UART_FCR, 0);

	(void)serial_in(info, UART_RX);    /* read data port to reset things */
	
	if (info->tty)
		set_bit(TTY_IO_ERROR, &info->tty->flags);