source: rtems-libbsd/rtemsbsd/rtems/rtems-kernel-termioskqueuepoll.c @ 028bf82

/**
 * @file
 *
 * @ingroup rtems_bsd_rtems
 *
 * @brief TODO.
 */

/*
 * Copyright (c) 2017 embedded brains GmbH.
 * All rights reserved.
 *
 *  embedded brains GmbH
 *  Dornierstr. 4
 *  82178 Puchheim
 *  Germany
 *  <rtems@embedded-brains.de>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <machine/rtems-bsd-kernel-space.h>

#include <sys/cdefs.h>
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/event.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/pcpu.h>
#include <sys/poll.h>
#include <sys/selinfo.h>

#include <rtems/termiostypes.h>
#include <rtems/irq-extension.h>

SYSINIT_REFERENCE(irqs);

typedef struct {
        rtems_termios_tty *tty;
        struct selinfo sel;
        rtems_interrupt_server_request request;
} termios_selinfo;

static bool
termios_is_eol(const rtems_termios_tty *tty, char c)
{

        return (c == '\n' || c == tty->termios.c_cc[VEOF] ||
            c == tty->termios.c_cc[VEOL] ||
            c == tty->termios.c_cc[VEOL2]);
}

static bool
termios_can_read(rtems_termios_tty *tty)
{
        rtems_termios_device_context *ctx;
        rtems_interrupt_lock_context lock_context;
        unsigned int i;
        unsigned int size;
        unsigned int raw_content_size;
        bool can;

        if (tty->handler.mode == TERMIOS_POLLED) {
                return (true);
        }

        if (tty->cindex != tty->ccount) {
                return (true);
        }

        ctx = tty->device_context;
        rtems_termios_device_lock_acquire(ctx, &lock_context);
        i = tty->rawInBuf.Head;
        size = tty->rawInBuf.Size;
        raw_content_size = (tty->rawInBuf.Tail - i) % size;

        if ((tty->termios.c_lflag & ICANON) != 0) {
                unsigned int todo = raw_content_size;

                /*
                 * FIXME: What to do in case of a raw input buffer overflow?
                 * For now, indicated that we can read.  However, this has
                 * problems in case an erase takes place.
                 */
                can = raw_content_size == (size - 1);

                while (todo > 0 && !can) {
                        char c;

                        i = (i + 1) % size;
                        c = tty->rawInBuf.theBuf[i];
                        can = termios_is_eol(tty, c);
                        --todo;
                }
        } else {
                cc_t vmin = tty->termios.c_cc[VMIN];

                if (vmin == 0) {
                        vmin = 1;
                }

                can = raw_content_size >= vmin;
        }

        if (!can) {
                tty->tty_rcvwakeup = false;
        }

        rtems_termios_device_lock_release(ctx, &lock_context);
        return (can);
}

static bool
termios_can_write(const rtems_termios_tty *tty)
{
        rtems_termios_device_context *ctx;
        rtems_interrupt_lock_context lock_context;
        bool can;

        if (tty->handler.mode == TERMIOS_POLLED) {
                return (true);
        }

        ctx = tty->device_context;
        rtems_termios_device_lock_acquire(ctx, &lock_context);
        can = ((tty->rawOutBuf.Tail - tty->rawOutBuf.Head - 1) %
            tty->rawOutBuf.Size) > 0;
        rtems_termios_device_lock_release(ctx, &lock_context);
        return (can);
}

static void
termios_receive_wakeup(void *arg)
{
        termios_selinfo *ts;
        rtems_termios_tty *tty;

        ts = arg;
        tty = ts->tty;

        rtems_mutex_lock(&tty->isem);
        selwakeup(&ts->sel);
        rtems_mutex_unlock(&tty->isem);
}

static void
termios_transmit_wakeup(void *arg)
{
        termios_selinfo *ts;
        rtems_termios_tty *tty;

        ts = arg;
        tty = ts->tty;

        rtems_mutex_lock(&tty->osem);
        selwakeup(&ts->sel);
        rtems_mutex_unlock(&tty->osem);
}

static void
termios_wakeup(struct termios *term, void *arg)
{
        termios_selinfo *ts = arg;

        rtems_interrupt_server_request_submit(&ts->request);
}

static struct selinfo *
termios_get_selinfo(rtems_termios_tty *tty, struct ttywakeup *wk,
    rtems_interrupt_handler handler)
{
        termios_selinfo *ts = wk->sw_arg;

        if (ts == NULL) {
                BSD_ASSERT(wk->sw_pfn == NULL);
                ts = malloc(sizeof(*ts), M_TEMP, M_WAITOK | M_ZERO);
                ts->tty = tty;
                rtems_interrupt_server_request_initialize(RTEMS_INTERRUPT_SERVER_DEFAULT,
                    &ts->request, handler, ts);
                wk->sw_arg = ts;
                wk->sw_pfn = termios_wakeup;
        } else {
                BSD_ASSERT(wk->sw_pfn == termios_wakeup);
        }

        return (&ts->sel);
}

int
rtems_termios_kqfilter(rtems_libio_t *iop, struct knote  *kn)
{

        return (EINVAL);
}

int
rtems_termios_poll(rtems_libio_t *iop, int events)
{
        struct thread *td = rtems_bsd_get_curthread_or_wait_forever();
        struct selinfo *sel;
        rtems_termios_tty *tty;
        int revents;

        revents = 0;
        tty = iop->data1;

        if ((events & (POLLIN | POLLRDNORM)) != 0) {
                sel = termios_get_selinfo(tty, &tty->tty_rcv,
                    termios_receive_wakeup);

                rtems_mutex_lock(&tty->isem);

                if (termios_can_read(tty)) {
                        revents |= events & (POLLIN | POLLRDNORM);
                } else {
                        selrecord(td, sel);
                }

                rtems_mutex_unlock(&tty->isem);
        }

        if ((events & (POLLOUT | POLLWRNORM)) != 0) {
                sel = termios_get_selinfo(tty, &tty->tty_snd,
                    termios_transmit_wakeup);

                rtems_mutex_lock(&tty->osem);

                if (termios_can_write(tty)) {
                        revents |= events & (POLLOUT | POLLWRNORM);
                } else {
                        selrecord(td, sel);
                }

                rtems_mutex_unlock(&tty->osem);
        }

        return (revents);
}

static void
termioskqueuepoll_sysinit(void)
{

        /* Do nothing */
}

SYSINIT(termioskqueuepoll, SI_SUB_TUNABLES, SI_ORDER_ANY,
    termioskqueuepoll_sysinit, NULL);