serial.c

基于16450/16550A的多串口驱动,估计很多人在找吧

 * ---------------------------------------------------------------
 */

#ifndef CONFIG_COLDFIRE
/*
 * Grab all interrupts in preparation for doing an automatic irq
 * detection.  dontgrab is a mask of irq's _not_ to grab.  Returns a
 * mask of irq's which were grabbed and should therefore be freed
 * using free_all_interrupts().
 */
static int grab_all_interrupts(int dontgrab)
{
	int 			irq_lines = 0;
	int			i, mask;
	
	for (i = 0, mask = 1; i < 16; i++, mask <<= 1) {
		if (!(mask & dontgrab) && !request_irq(i, rs_probe, SA_INTERRUPT, "serial probe", NULL)) {
			irq_lines |= mask;
		}
	}
	return irq_lines;
}

/*
 * Release all interrupts grabbed by grab_all_interrupts
 */
static void free_all_interrupts(int irq_lines)
{
	int	i;
	
	for (i = 0; i < 16; i++) {
		if (irq_lines & (1 << i))
			free_irq(i, NULL);
	}
}
#endif /* CONFIG_COLDFIRE */

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

static int startup(struct async_struct * info)
{
	unsigned int ICP;
	unsigned long flags;
	int	retval;
	void (*handler)(int, void *, struct pt_regs *);
	unsigned long page;

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

	
	save_flags(flags); cli();

	if (info->flags & ASYNC_INITIALIZED) {
		free_page(page);
		restore_flags(flags);
		return 0;
	}

	if (!info->port || !info->type) {
		if (info->tty)
			set_bit(TTY_IO_ERROR, &info->tty->flags);
		free_page(page);
		restore_flags(flags);
		return 0;
	}
	if (info->xmit_buf)
		free_page(page);
	else
		info->xmit_buf = (unsigned char *) page;

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

	/*
	 * Clear the FIFO buffers and disable them
	 * (they will be reenabled in change_speed())
	 */
	if (info->type == PORT_16650) {
		serial_outp(info, UART_FCR, (UART_FCR_CLEAR_RCVR |
					     UART_FCR_CLEAR_XMIT));
		info->xmit_fifo_size = 1; /* disabled for now */
	} else if (info->type == PORT_16550A) {
		serial_outp(info, UART_FCR, (UART_FCR_CLEAR_RCVR |
					     UART_FCR_CLEAR_XMIT));
		info->xmit_fifo_size = 16;
	} else
		info->xmit_fifo_size = 1;

	/*
	 * 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) {
		restore_flags(flags);
		if (suser()) {
			if (info->tty)
				set_bit(TTY_IO_ERROR, &info->tty->flags);
			return 0;
		} else
			return -ENODEV;
	}
	
#ifndef CONFIG_COLDFIRE
	/*
	 * Allocate the IRQ if necessary
	 */
	if (info->irq && (!IRQ_ports[IRQMASK(info->irq)] ||
			  !IRQ_ports[IRQMASK(info->irq)]->next_port)) {
		if (IRQ_ports[IRQMASK(info->irq)]) {
			free_irq(info->irq, NULL);
			if (rs_multiport[IRQMASK(info->irq)].port1)
				handler = rs_interrupt_multi;
			else
				handler = rs_interrupt;
		} else 
			handler = rs_interrupt_single;

		retval = request_irq(info->irq, handler, IRQ_T(info),
				     "serial", NULL);
		if (retval) {
			restore_flags(flags);
			if (suser()) {
				if (info->tty)
					set_bit(TTY_IO_ERROR,
						&info->tty->flags);
				return 0;
			} else
				return retval;
		}
	}
#endif

	/*
	 * Clear the interrupt registers.
	 */
     /* (void) serial_inp(info, UART_LSR); */   /* (see above) */
	(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 */
	if (info->flags & ASYNC_FOURPORT) {
		info->MCR = UART_MCR_DTR | UART_MCR_RTS;
		info->MCR_noint = UART_MCR_DTR | UART_MCR_OUT1;
	} else {
		info->MCR = UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2;
		info->MCR_noint = UART_MCR_DTR | UART_MCR_RTS;
	}
#if defined(__alpha__) && !defined(CONFIG_PCI)
	info->MCR |= UART_MCR_OUT1 | UART_MCR_OUT2;
	info->MCR_noint |= UART_MCR_OUT1 | UART_MCR_OUT2;
#endif
	if (info->irq == 0)
		info->MCR = info->MCR_noint;
	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 */
	
	if (info->flags & ASYNC_FOURPORT) {
		/* Enable interrupts on the AST Fourport board */
		ICP = (info->port & 0xFE0) | 0x01F;
		outb_p(0x80, ICP);
		(void) inb_p(ICP);
	}

	/*
	 * 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;

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

	/*
	 * Set up serial timers...
	 */
	timer_table[RS_TIMER].expires = jiffies + 2*HZ/100;
	timer_active |= 1 << RS_TIMER;

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

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

/*
 * 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;
	int		retval;

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

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

	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 */
	if (info->flags & ASYNC_FOURPORT) {
		/* reset interrupts on the AST Fourport board */
		(void) inb((info->port & 0xFE0) | 0x01F);
	}
	
	if (!info->tty || (info->tty->termios->c_cflag & HUPCL)) {
		info->MCR &= ~(UART_MCR_DTR|UART_MCR_RTS);
		info->MCR_noint &= ~(UART_MCR_DTR|UART_MCR_RTS);
	}
	serial_outp(info, UART_MCR, info->MCR_noint);

	/* 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);
#ifdef CONFIG_LEDMAN
	ledman_cmd(LEDMAN_CMD_OFF, info->line ? LEDMAN_COM2_DCD : LEDMAN_COM1_DCD);
#endif
	
	info->flags &= ~ASYNC_INITIALIZED;
	restore_flags(flags);
}

/*
 * 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 async_struct *info)
{
	unsigned int port;
	int	quot = 0;
	unsigned cflag,cval,fcr;
	int	i;
	unsigned long flags;

	if (!info->tty || !info->tty->termios)
		return;
	cflag = info->tty->termios->c_cflag;
	if (!(port = info->port))
		return;
	i = cflag & CBAUD;
	if (i & CBAUDEX) {
		i &= ~CBAUDEX;
		if (i < 1 || i > 2) 
			info->tty->termios->c_cflag &= ~CBAUDEX;
		else
			i += 15;
	}
	if (i == 15) {
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
			i += 1;
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
			i += 2;
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST)
			quot = info->custom_divisor;
	}
	if (quot) {
		info->timeout = ((info->xmit_fifo_size*HZ*15*quot) /
				 info->baud_base) + 2;
	} else if (baud_table[i] == 134) {
		quot = (2*info->baud_base / 269);
		info->timeout = (info->xmit_fifo_size*HZ*30/269) + 2;
	} else if (baud_table[i]) {
		quot = info->baud_base / baud_table[i];
		info->timeout = (info->xmit_fifo_size*HZ*15/baud_table[i]) + 2;
	} else {
		quot = 0;
		info->timeout = 0;
	}
	if (quot) {
		info->MCR |= UART_MCR_DTR;
		info->MCR_noint |= UART_MCR_DTR;
		save_flags(flags); cli();
		serial_out(info, UART_MCR, info->MCR);
		restore_flags(flags);
	} else {
		info->MCR &= ~UART_MCR_DTR;
		info->MCR_noint &= ~UART_MCR_DTR;
		save_flags(flags); cli();
		serial_out(info, UART_MCR, info->MCR);
		restore_flags(flags);
		return;
	}
	/* byte size and parity */
	switch (cflag & CSIZE) {
	      case CS5: cval = 0x00; break;
	      case CS6: cval = 0x01; break;
	      case CS7: cval = 0x02; break;
	      case CS8: cval = 0x03; break;
	      default:  cval = 0x00; break;	/* too keep GCC shut... */
	}
	if (cflag & CSTOPB) {
		cval |= 0x04;
	}
	if (cflag & PARENB)
		cval |= UART_LCR_PARITY;
	if (!(cflag & PARODD))
		cval |= UART_LCR_EPAR;
	if (info->type == PORT_16550A) {
		if ((info->baud_base / quot) < 2400)
			fcr = UART_FCR_ENABLE_FIFO | UART_FCR_TRIGGER_1;
		else
			fcr = UART_FCR_ENABLE_FIFO | UART_FCR_TRIGGER_8;
	} else if (info->type == PORT_16650) {
		/*
		 * On the 16650, we disable the FIFOs altogether
		 * because of a design bug in how the implement
		 * things.  We could support it by completely changing
		 * how we handle the interrupt driver, but not today....
		 *
		 * N.B.  Because there's no way to set a FIFO trigger
		 * at 1 char, we'd probably disable at speed below
		 * 2400 baud anyway...
		 */
		fcr = 0;
	} else
		fcr = 0;
	
	/* CTS flow control flag and modem status interrupts */
	info->IER &= ~UART_IER_MSI;
	if (cflag & CRTSCTS) {
		info->flags |= ASYNC_CTS_FLOW;
		info->IER |= UART_IER_MSI;
	} else
		info->flags &= ~ASYNC_CTS_FLOW;
	if (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
	 */
#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;
	
	info->ignore_status_mask = 0;
#if 0
	/* This should be safe, but for some broken bits of hardware... */
	if (I_IGNPAR(info->tty)) {
		info->ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
		info->read_status_mask |= UART_LSR_PE | UART_LSR_FE;
	}
#endif
	if (I_IGNBRK(info->tty)) {
		info->ignore_status_mask |= UART_LSR_BI;
		info->read_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 | \
				UART_LSR_PE | UART_LSR_FE;
			info->read_status_mask |= UART_LSR_OE | \
				UART_LSR_PE | UART_LSR_FE;
		}
	}
	save_flags(flags); cli();
	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 */
	serial_outp(info, UART_LCR, cval);		/* reset DLAB */
	serial_outp(info, UART_FCR, fcr); 	/* set fcr */
	restore_flags(flags);
}

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

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

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