text: #include <linux/interrupt.h>
  #include <linux/ioport.h>
  
  #include "spk_types.h"
  #include "speakup.h"
  #include "spk_priv.h"
  #include "serialio.h"
  
  #ifndef SERIAL_PORT_DFNS
  #define SERIAL_PORT_DFNS
  #endif
  
  static void start_serial_interrupt(int irq);
  
  static const struct old_serial_port rs_table[] = {
  	SERIAL_PORT_DFNS
  };
  static const struct old_serial_port *serstate;
  static int timeouts;
  
  const struct old_serial_port *spk_serial_init(int index)
  {
  	int baud = 9600, quot = 0;
  	unsigned int cval = 0;
  	int cflag = CREAD | HUPCL | CLOCAL | B9600 | CS8;
  	const struct old_serial_port *ser = rs_table + index;
  	int err;
  
  	/*	Divisor, bytesize and parity */
  	quot = ser->baud_base / baud;
  	cval = cflag & (CSIZE | CSTOPB);
  #if defined(__powerpc__) || defined(__alpha__)
  	cval >>= 8;
  #else /* !__powerpc__ && !__alpha__ */
  	cval >>= 4;
  #endif /* !__powerpc__ && !__alpha__ */
  	if (cflag & PARENB)
  		cval |= UART_LCR_PARITY;
  	if (!(cflag & PARODD))
  		cval |= UART_LCR_EPAR;
  	if (synth_request_region(ser->port, 8)) {
  		/* try to take it back. */
  		pr_info("Ports not available, trying to steal them\n");
  		__release_region(&ioport_resource, ser->port, 8);
  		err = synth_request_region(ser->port, 8);
  		if (err) {
  			pr_warn("Unable to allocate port at %x, errno %i",
  				ser->port, err);
  			return NULL;
  		}
  	}
  
  	/*	Disable UART interrupts, set DTR and RTS high
  	 *	and set speed.
  	 */
  	outb(cval | UART_LCR_DLAB, ser->port + UART_LCR);	/* set DLAB */
  	outb(quot & 0xff, ser->port + UART_DLL);	/* LS of divisor */
  	outb(quot >> 8, ser->port + UART_DLM);		/* MS of divisor */
  	outb(cval, ser->port + UART_LCR);		/* reset DLAB */
  
  	/* Turn off Interrupts */
  	outb(0, ser->port + UART_IER);
  	outb(UART_MCR_DTR | UART_MCR_RTS, ser->port + UART_MCR);
  
  	/* If we read 0xff from the LSR, there is no UART here. */
  	if (inb(ser->port + UART_LSR) == 0xff) {
  		synth_release_region(ser->port, 8);
  		serstate = NULL;
  		return NULL;
  	}
  
  	mdelay(1);
  	speakup_info.port_tts = ser->port;
  	serstate = ser;
  
  	start_serial_interrupt(ser->irq);
  
  	return ser;
  }
  
  static irqreturn_t synth_readbuf_handler(int irq, void *dev_id)
  {
  	unsigned long flags;
  /*printk(KERN_ERR "in irq\n"); */
  /*pr_warn("in IRQ\n"); */
  	int c;
  
  	spin_lock_irqsave(&speakup_info.spinlock, flags);
  	while (inb_p(speakup_info.port_tts + UART_LSR) & UART_LSR_DR) {
  
  		c = inb_p(speakup_info.port_tts+UART_RX);
  		synth->read_buff_add((u_char) c);
  /*printk(KERN_ERR "c = %d\n", c); */
  /*pr_warn("C = %d\n", c); */
  	}
  	spin_unlock_irqrestore(&speakup_info.spinlock, flags);
  	return IRQ_HANDLED;
  }
  
  static void start_serial_interrupt(int irq)
  {
  	int rv;
  
  	if (synth->read_buff_add == NULL)
  		return;
  
  	rv = request_irq(irq, synth_readbuf_handler, IRQF_SHARED,
  			 "serial", (void *) synth_readbuf_handler);
  
  	if (rv)
  		pr_err("Unable to request Speakup serial I R Q\n");
  	/* Set MCR */
  	outb(UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2,
  			speakup_info.port_tts + UART_MCR);
  	/* Turn on Interrupts */
  	outb(UART_IER_MSI|UART_IER_RLSI|UART_IER_RDI,
  			speakup_info.port_tts + UART_IER);
  	inb(speakup_info.port_tts+UART_LSR);
  	inb(speakup_info.port_tts+UART_RX);
  	inb(speakup_info.port_tts+UART_IIR);
  	inb(speakup_info.port_tts+UART_MSR);
  	outb(1, speakup_info.port_tts + UART_FCR);	/* Turn FIFO On */
  }
  
  void spk_stop_serial_interrupt(void)
  {
  	if (speakup_info.port_tts == 0)
  		return;
  
  	if (synth->read_buff_add == NULL)
  		return;
  
  	/* Turn off interrupts */
  	outb(0, speakup_info.port_tts+UART_IER);
  	/* Free IRQ */
  	free_irq(serstate->irq, (void *) synth_readbuf_handler);
  }
  
  int spk_wait_for_xmitr(void)
  {
  	int tmout = SPK_XMITR_TIMEOUT;
  
  	if ((synth->alive) && (timeouts >= NUM_DISABLE_TIMEOUTS)) {
  		pr_warn("%s: too many timeouts, deactivating speakup\n",
  			synth->long_name);
  		synth->alive = 0;
  		/* No synth any more, so nobody will restart TTYs, and we thus
  		 * need to do it ourselves.  Now that there is no synth we can
  		 * let application flood anyway
  		 */
  		speakup_start_ttys();
  		timeouts = 0;
  		return 0;
  	}
  	while (spk_serial_tx_busy()) {
  		if (--tmout == 0) {
  			pr_warn("%s: timed out (tx busy)\n", synth->long_name);
  			timeouts++;
  			return 0;
  		}
  		udelay(1);
  	}
  	tmout = SPK_CTS_TIMEOUT;
  	while (!((inb_p(speakup_info.port_tts + UART_MSR)) & UART_MSR_CTS)) {
  		/* CTS */
  		if (--tmout == 0) {
  			/* pr_warn("%s: timed out (cts)\n",
  			 * synth->long_name);
  			 */
  			timeouts++;
  			return 0;
  		}
  		udelay(1);
  	}
  	timeouts = 0;
  	return 1;
  }
  
  unsigned char spk_serial_in(void)
  {
  	int tmout = SPK_SERIAL_TIMEOUT;
  
  	while (!(inb_p(speakup_info.port_tts + UART_LSR) & UART_LSR_DR)) {
  		if (--tmout == 0) {
  			pr_warn("time out while waiting for input.\n");
  			return 0xff;
  		}
  		udelay(1);
  	}
  	return inb_p(speakup_info.port_tts + UART_RX);
  }
  EXPORT_SYMBOL_GPL(spk_serial_in);
  
  unsigned char spk_serial_in_nowait(void)
  {
  	unsigned char lsr;
  
  	lsr = inb_p(speakup_info.port_tts + UART_LSR);
  	if (!(lsr & UART_LSR_DR))
  		return 0;
  	return inb_p(speakup_info.port_tts + UART_RX);
  }
  EXPORT_SYMBOL_GPL(spk_serial_in_nowait);
  
  int spk_serial_out(const char ch)
  {
  	if (synth->alive && spk_wait_for_xmitr()) {
  		outb_p(ch, speakup_info.port_tts);
  		return 1;
  	}
  	return 0;
  }
  EXPORT_SYMBOL_GPL(spk_serial_out);
  
  void spk_serial_release(void)
  {
  	if (speakup_info.port_tts == 0)
  		return;
  	synth_release_region(speakup_info.port_tts, 8);
  	speakup_info.port_tts = 0;
  }
  EXPORT_SYMBOL_GPL(spk_serial_release);
  