// 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);