serialio.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/interrupt.h>
#include <linux/ioport.h>

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

#include <linux/serial_core.h>
/* WARNING:  Do not change this to <linux/serial.h> without testing that
 * SERIAL_PORT_DFNS does get defined to the appropriate value.
 */
#include <asm/serial.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;

static int spk_serial_out(struct spk_synth *in_synth, const char ch);
static void spk_serial_send_xchar(struct spk_synth *in_synth, char ch);
static void spk_serial_tiocmset(struct spk_synth *in_synth, unsigned int set, unsigned int clear);
static unsigned char spk_serial_in(struct spk_synth *in_synth);
static unsigned char spk_serial_in_nowait(struct spk_synth *in_synth);
static void spk_serial_flush_buffer(struct spk_synth *in_synth);
static int spk_serial_wait_for_xmitr(struct spk_synth *in_synth);

struct spk_io_ops spk_serial_io_ops = {
	.synth_out = spk_serial_out,
	.send_xchar = spk_serial_send_xchar,
	.tiocmset = spk_serial_tiocmset,
	.synth_in = spk_serial_in,
	.synth_in_nowait = spk_serial_in_nowait,
	.flush_buffer = spk_serial_flush_buffer,
	.wait_for_xmitr = spk_serial_wait_for_xmitr,
};
EXPORT_SYMBOL_GPL(spk_serial_io_ops);

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;
	int err;

	if (index >= ARRAY_SIZE(rs_table)) {
		pr_info("no port info for ttyS%d\n", index);
		return NULL;
	}
	ser = rs_table + index;

	/*	Divisor, byte size 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;
	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);
	}
	spin_unlock_irqrestore(&speakup_info.spinlock, flags);
	return IRQ_HANDLED;
}

static void start_serial_interrupt(int irq)
{
	int rv;

	if (!synth->read_buff_add)
		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 */
}

static void spk_serial_send_xchar(struct spk_synth *synth, char ch)
{
	int timeout = SPK_XMITR_TIMEOUT;

	while (spk_serial_tx_busy()) {
		if (!--timeout)
			break;
		udelay(1);
	}
	outb(ch, speakup_info.port_tts);
}

static void spk_serial_tiocmset(struct spk_synth *in_synth, unsigned int set, unsigned int clear)
{
	int old = inb(speakup_info.port_tts + UART_MCR);

	outb((old & ~clear) | set, speakup_info.port_tts + UART_MCR);
}

int spk_serial_synth_probe(struct spk_synth *synth)
{
	const struct old_serial_port *ser;
	int failed = 0;

	if ((synth->ser >= SPK_LO_TTY) && (synth->ser <= SPK_HI_TTY)) {
		ser = spk_serial_init(synth->ser);
		if (!ser) {
			failed = -1;
		} else {
			outb_p(0, ser->port);
			mdelay(1);
			outb_p('\r', ser->port);
		}
	} else {
		failed = -1;
		pr_warn("ttyS%i is an invalid port\n", synth->ser);
	}
	if (failed) {
		pr_info("%s: not found\n", synth->long_name);
		return -ENODEV;
	}
	pr_info("%s: ttyS%i, Driver Version %s\n",
		synth->long_name, synth->ser, synth->version);
	synth->alive = 1;
	return 0;
}
EXPORT_SYMBOL_GPL(spk_serial_synth_probe);

void spk_stop_serial_interrupt(void)
{
	if (speakup_info.port_tts == 0)
		return;

	if (!synth->read_buff_add)
		return;

	/* Turn off interrupts */
	outb(0, speakup_info.port_tts + UART_IER);
	/* Free IRQ */
	free_irq(serstate->irq, (void *)synth_readbuf_handler);
}
EXPORT_SYMBOL_GPL(spk_stop_serial_interrupt);

static int spk_serial_wait_for_xmitr(struct spk_synth *in_synth)
{
	int tmout = SPK_XMITR_TIMEOUT;

	if ((in_synth->alive) && (timeouts >= NUM_DISABLE_TIMEOUTS)) {
		pr_warn("%s: too many timeouts, deactivating speakup\n",
			in_synth->long_name);
		in_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",
				in_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) {
			timeouts++;
			return 0;
		}
		udelay(1);
	}
	timeouts = 0;
	return 1;
}

static unsigned char spk_serial_in(struct spk_synth *in_synth)
{
	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);
}

static unsigned char spk_serial_in_nowait(struct spk_synth *in_synth)
{
	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);
}

static void spk_serial_flush_buffer(struct spk_synth *in_synth)
{
	/* TODO: flush the UART 16550 buffer */
}

static int spk_serial_out(struct spk_synth *in_synth, const char ch)
{
	if (in_synth->alive && spk_serial_wait_for_xmitr(in_synth)) {
		outb_p(ch, speakup_info.port_tts);
		return 1;
	}
	return 0;
}

const char *spk_serial_synth_immediate(struct spk_synth *synth,
				       const char *buff)
{
	u_char ch;

	while ((ch = *buff)) {
		if (ch == '\n')
			ch = synth->procspeech;
		if (spk_serial_wait_for_xmitr(synth))
			outb(ch, speakup_info.port_tts);
		else
			return buff;
		buff++;
	}
	return NULL;
}
EXPORT_SYMBOL_GPL(spk_serial_synth_immediate);

void spk_serial_release(struct spk_synth *synth)
{
	spk_stop_serial_interrupt();
	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);