1. 根目录:
2. drivers
3. staging
4. speakup
5. serialio.c

#include <linux/interrupt.h>
#include <linux/ioport.h>

#include "spk_types.h"
#include "speakup.h"
#include "spk_priv.h"
#include "serialio.h"

static void start_serial_interrupt(int irq);

static struct serial_state rs_table[] = {
	SERIAL_PORT_DFNS
};
static struct serial_state *serstate;
static int timeouts;

struct serial_state *spk_serial_init(int index)
{
	int baud = 9600, quot = 0;
	unsigned int cval = 0;
	int cflag = CREAD | HUPCL | CLOCAL | B9600 | CS8;
	struct serial_state *ser = NULL;
	int err;

	ser = rs_table + index;
	/*	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. */
		printk(KERN_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 %lx, 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;
	spk_lock(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); */
	}
	spk_unlock(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)
		printk(KERN_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 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 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 && 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);