static int
cmx_filter_read(struct knote *kn, long hint)
{
struct cmx_softc *sc = (struct cmx_softc *)kn->kn_hook;
int ready = 0;
uint8_t bsr = 0;
if (sc == NULL || sc->dying) {
kn->kn_flags |= EV_EOF;
return (1);
}
bsr = cmx_read_BSR(sc);
if (cmx_test(bsr, BSR_BULK_IN_FULL, 1)) {
ready = 1;
} else {
CMX_LOCK(sc);
if (!sc->polling) {
sc->polling = 1;
callout_reset(&sc->ch, POLL_TICKS,
cmx_tick, sc);
}
CMX_UNLOCK(sc);
}
return (ready);
}
/*
* Periodical callout routine, polling the reader for data
* availability. If the reader signals data ready for reading,
* wakes up the processes which are waiting in select()/poll().
* Otherwise, reschedules itself with a delay of POLL_TICKS.
*/
static void
cmx_tick(void *xsc)
{
struct cmx_softc *sc = xsc;
uint8_t bsr;
CMX_LOCK(sc);
if (sc->polling && !sc->dying) {
bsr = cmx_read_BSR(sc);
DEBUG_printf(sc->dev, "BSR=%b\n", bsr, BSRBITS);
if (cmx_test(bsr, BSR_BULK_IN_FULL, 1)) {
sc->polling = 0;
selwakeuppri(&sc->sel, PZERO);
} else {
callout_reset(&sc->ch, POLL_TICKS, cmx_tick, sc);
}
}
CMX_UNLOCK(sc);
}
/*
* Poll handler. Writing is always possible, reading is only possible
* if BSR_BULK_IN_FULL is set. Will start the cmx_tick callout and
* set sc->polling.
*/
static int
cmx_poll(struct cdev *cdev, int events, struct thread *td)
{
struct cmx_softc *sc = cdev->si_drv1;
int revents = 0;
uint8_t bsr = 0;
if (sc == NULL || sc->dying)
return ENXIO;
bsr = cmx_read_BSR(sc);
DEBUG_printf(sc->dev, "called (events=%b BSR=%b)\n",
events, POLLBITS, bsr, BSRBITS);
revents = events & (POLLOUT | POLLWRNORM);
if (events & (POLLIN | POLLRDNORM)) {
if (cmx_test(bsr, BSR_BULK_IN_FULL, 1)) {
revents |= events & (POLLIN | POLLRDNORM);
} else {
selrecord(td, &sc->sel);
CMX_LOCK(sc);
if (!sc->polling) {
DEBUG_printf(sc->dev, "enabling polling\n");
sc->polling = 1;
callout_reset(&sc->ch, POLL_TICKS,
cmx_tick, sc);
} else {
DEBUG_printf(sc->dev, "already polling\n");
}
CMX_UNLOCK(sc);
}
}
DEBUG_printf(sc->dev, "success (revents=%b)\n", revents, POLLBITS);
return revents;
}
