/*      $NetBSD: midi.c,v 1.101 2022/10/23 23:03:30 riastradh Exp $     */

/*
* Copyright (c) 1998, 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Lennart Augustsson ([email protected]), (MIDI FST and Active
* Sense handling) Chapman Flack ([email protected]), and Andrew Doran.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: midi.c,v 1.101 2022/10/23 23:03:30 riastradh Exp $");

#ifdef _KERNEL_OPT
#include "midi.h"
#endif

#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <sys/vnode.h>
#include <sys/select.h>
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/syslog.h>
#include <sys/kernel.h>
#include <sys/signalvar.h>
#include <sys/conf.h>
#include <sys/audioio.h>
#include <sys/midiio.h>
#include <sys/device.h>
#include <sys/intr.h>
#include <sys/module.h>

#include <dev/audio/audio_if.h>
#include <dev/midi_if.h>
#include <dev/midivar.h>

#include "ioconf.h"

#if NMIDI > 0

#ifdef AUDIO_DEBUG
#define DPRINTF(x)      if (mididebug) printf x
#define DPRINTFN(n,x)   if (mididebug >= (n)) printf x
int     mididebug = 0;
/*
*      1: detected protocol errors and buffer overflows
*      2: probe, attach, detach
*      3: open, close
*      4: data received except realtime
*      5: ioctl
*      6: read, write, poll
*      7: data transmitted
*      8: uiomoves, synchronization
*      9: realtime data received
*/
#else
#define DPRINTF(x)
#define DPRINTFN(n,x)
#endif

static  struct midi_softc *hwif_softc = NULL;
static  kmutex_t hwif_softc_lock;

static void     midi_in(void *, int);
static void     midi_out(void *);
static int      midi_poll_out(struct midi_softc *);
static int      midi_intr_out(struct midi_softc *);
static int      midi_msg_out(struct midi_softc *, u_char **, u_char **,
                            u_char **, u_char **);
static int      midi_start_output(struct midi_softc *);
static void     midi_initbuf(struct midi_buffer *);
static void     midi_xmt_asense(void *);
static void     midi_rcv_asense(void *);
static void     midi_softint(void *);

static int      midiprobe(device_t, cfdata_t, void *);
static void     midiattach(device_t, device_t, void *);
int             mididetach(device_t, int);
static int      midiactivate(device_t, enum devact);

static dev_type_open(midiopen);
static dev_type_close(midiclose);
static dev_type_read(midiread);
static dev_type_write(midiwrite);
static dev_type_ioctl(midiioctl);
static dev_type_poll(midipoll);
static dev_type_kqfilter(midikqfilter);

const struct cdevsw midi_cdevsw = {
       .d_open = midiopen,
       .d_close = midiclose,
       .d_read = midiread,
       .d_write = midiwrite,
       .d_ioctl = midiioctl,
       .d_stop = nostop,
       .d_tty = notty,
       .d_poll = midipoll,
       .d_mmap = nommap,
       .d_kqfilter = midikqfilter,
       .d_discard = nodiscard,
       .d_flag = D_OTHER | D_MPSAFE
};

CFATTACH_DECL_NEW(midi, sizeof(struct midi_softc),
   midiprobe, midiattach, mididetach, midiactivate);

#define MIDI_XMT_ASENSE_PERIOD mstohz(275)
#define MIDI_RCV_ASENSE_PERIOD mstohz(300)

static int
midiprobe(device_t parent, cfdata_t match, void *aux)
{
       struct audio_attach_args *sa;

       sa = aux;

       DPRINTFN(2,("midiprobe: type=%d sa=%p hw=%p\n", sa->type, sa,
           sa->hwif));

       return sa->type == AUDIODEV_TYPE_MIDI;
}

static void
midiattach(device_t parent, device_t self, void *aux)
{
       struct midi_softc *sc = device_private(self);
       struct audio_attach_args *sa = aux;
       const struct midi_hw_if *hwp;
       void *hdlp;

       hwp = sa->hwif;
       hdlp = sa->hdl;

       aprint_naive("\n");

       DPRINTFN(2, ("MIDI attach\n"));

#ifdef DIAGNOSTIC
       if (hwp == 0 ||
           hwp->open == 0 ||
           hwp->close == 0 ||
           hwp->output == 0 ||
           hwp->getinfo == 0) {
               aprint_error_dev(self, "missing method\n");
               return;
       }
#endif

       sc->dev = self;
       sc->hw_if = hwp;
       sc->hw_hdl = hdlp;
       midi_attach(sc);
}

static int
midiactivate(device_t self, enum devact act)
{
       struct midi_softc *sc = device_private(self);

       switch (act) {
       case DVACT_DEACTIVATE:
               mutex_enter(sc->lock);
               sc->dying = 1;
               mutex_exit(sc->lock);
               return 0;
       default:
               return EOPNOTSUPP;
       }
}

int
mididetach(device_t self, int flags)
{
       struct midi_softc *sc = device_private(self);
       int maj, mn;

       DPRINTFN(2,("%s: sc=%p flags=%d\n", __func__, sc, flags));

       pmf_device_deregister(self);

       mutex_enter(sc->lock);
       sc->dying = 1;
       cv_broadcast(&sc->wchan);
       cv_broadcast(&sc->rchan);

       if (--sc->refcnt >= 0) {
               (void)cv_timedwait(&sc->detach_cv, sc->lock, hz * 60);
               if (sc->refcnt >= 0) {
                       aprint_error_dev(self, "refcnt failed to drain,"
                           " bashing my brains out anyway\n");
               }
       }
       mutex_exit(sc->lock);

       /* locate the major number */
       maj = cdevsw_lookup_major(&midi_cdevsw);

       /*
        * Nuke the vnodes for any open instances (calls close).
        * Will wait until any activity on the device nodes has ceased.
        *
        * XXXAD NOT YET.
        *
        * XXXAD NEED TO PREVENT NEW REFERENCES THROUGH AUDIO_ENTER().
        */
       mn = device_unit(self);
       vdevgone(maj, mn, mn, VCHR);

       if (!(sc->props & MIDI_PROP_NO_OUTPUT)) {
               evcnt_detach(&sc->xmt.bytesDiscarded);
               evcnt_detach(&sc->xmt.incompleteMessages);
       }
       if (sc->props & MIDI_PROP_CAN_INPUT) {
               evcnt_detach(&sc->rcv.bytesDiscarded);
               evcnt_detach(&sc->rcv.incompleteMessages);
       }

       if (sc->sih != NULL) {
               softint_disestablish(sc->sih);
               sc->sih = NULL;
       }

       callout_halt(&sc->xmt_asense_co, NULL);
       callout_halt(&sc->rcv_asense_co, NULL);

       callout_destroy(&sc->xmt_asense_co);
       callout_destroy(&sc->rcv_asense_co);

       cv_destroy(&sc->wchan);
       cv_destroy(&sc->rchan);
       cv_destroy(&sc->detach_cv);

       return (0);
}

void
midi_attach(struct midi_softc *sc)
{
       struct midi_info mi;
       kmutex_t *dummy;
       static int first = 1;

       if (first) {
               mutex_init(&hwif_softc_lock, MUTEX_DEFAULT, IPL_NONE);
               first = 0;
       }

       sc->hw_if->get_locks(sc->hw_hdl, &sc->lock, &dummy);

       callout_init(&sc->xmt_asense_co, CALLOUT_MPSAFE);
       callout_init(&sc->rcv_asense_co, CALLOUT_MPSAFE);
       callout_setfunc(&sc->xmt_asense_co, midi_xmt_asense, sc);
       callout_setfunc(&sc->rcv_asense_co, midi_rcv_asense, sc);

       sc->sih = softint_establish(SOFTINT_CLOCK | SOFTINT_MPSAFE,
           midi_softint, sc);

       cv_init(&sc->rchan, "midird");
       cv_init(&sc->wchan, "midiwr");
       cv_init(&sc->detach_cv, "mididet");

       sc->dying = 0;
       sc->isopen = 0;
       sc->refcnt = 0;

       mutex_enter(&hwif_softc_lock);
       mutex_enter(sc->lock);
       hwif_softc = sc;
       sc->hw_if->getinfo(sc->hw_hdl, &mi);
       hwif_softc = NULL;
       mutex_exit(sc->lock);
       mutex_exit(&hwif_softc_lock);

       sc->props = mi.props;

       if (!(sc->props & MIDI_PROP_NO_OUTPUT)) {
               evcnt_attach_dynamic(&sc->xmt.bytesDiscarded,
                       EVCNT_TYPE_MISC, NULL,
                       device_xname(sc->dev), "xmt bytes discarded");
               evcnt_attach_dynamic(&sc->xmt.incompleteMessages,
                       EVCNT_TYPE_MISC, NULL,
                       device_xname(sc->dev), "xmt incomplete msgs");
       }
       if (sc->props & MIDI_PROP_CAN_INPUT) {
               evcnt_attach_dynamic(&sc->rcv.bytesDiscarded,
                       EVCNT_TYPE_MISC, NULL,
                       device_xname(sc->dev), "rcv bytes discarded");
               evcnt_attach_dynamic(&sc->rcv.incompleteMessages,
                       EVCNT_TYPE_MISC, NULL,
                       device_xname(sc->dev), "rcv incomplete msgs");
       }

       aprint_naive("\n");
       aprint_normal(": %s\n", mi.name);

       if (!pmf_device_register(sc->dev, NULL, NULL))
               aprint_error_dev(sc->dev, "couldn't establish power handler\n");
}

void
midi_register_hw_if_ext(struct midi_hw_if_ext *exthw)
{
       if (hwif_softc != NULL) /* ignore calls resulting from non-init */
               hwif_softc->hw_if_ext = exthw; /* uses of getinfo */
}

int
midi_unit_count(void)
{
       int i;
       for ( i = 0; i < midi_cd.cd_ndevs; ++i)
               if (NULL == device_lookup(&midi_cd, i))
                       break;
       return i;
}

static void
midi_initbuf(struct midi_buffer *mb)
{
       mb->idx_producerp = mb->idx_consumerp = mb->idx;
       mb->buf_producerp = mb->buf_consumerp = mb->buf;
}

#define PACK_MB_IDX(cat,len) (((cat)<<4)|(len))
#define MB_IDX_CAT(idx) ((idx)>>4)
#define MB_IDX_LEN(idx) ((idx)&0xf)

static char const midi_cats[] = "\0\0\0\0\0\0\0\0\2\2\2\2\1\1\2\3";
#define MIDI_CAT(d) (midi_cats[((d)>>4)&15])
#define FST_RETURN(offp,endp,ret) \
       return (s->pos=s->msg+(offp)), (s->end=s->msg+(endp)), (ret)

enum fst_ret { FST_CHN, FST_CHV, FST_COM, FST_SYX, FST_RT, FST_MORE, FST_ERR,
              FST_HUH, FST_SXP };
enum fst_form { FST_CANON, FST_COMPR, FST_VCOMP };
static struct {
       int off;
       enum fst_ret tag;
} const midi_forms[] = {
       [FST_CANON] = { .off=0, .tag=FST_CHN },
       [FST_COMPR] = { .off=1, .tag=FST_CHN },
       [FST_VCOMP] = { .off=0, .tag=FST_CHV }
};
#define FST_CRETURN(endp) \
       FST_RETURN(midi_forms[form].off,endp,midi_forms[form].tag)

/*
* A MIDI finite state transducer suitable for receiving or transmitting. It
* will accept correct MIDI input that uses, doesn't use, or sometimes uses the
* 'running status' compression technique, and transduce it to fully expanded
* (form=FST_CANON) or fully compressed (form=FST_COMPR or FST_VCOMP) form.
*
* Returns FST_MORE if a complete message has not been parsed yet (SysEx
* messages are the exception), FST_ERR or FST_HUH if the input does not
* conform to the protocol, or FST_CHN (channel messages), FST_COM (System
* Common messages), FST_RT (System Real-Time messages), or FST_SYX (System
* Exclusive) to broadly categorize the message parsed. s->pos and s->end
* locate the parsed message; while (s->pos<s->end) putchar(*(s->pos++));
* would output it.
*
* FST_HUH means the character c wasn't valid in the original state, but the
* state has now been reset to START and the caller should try again passing
* the same c. FST_ERR means c isn't valid in the start state; the caller
* should kiss it goodbye and continue to try successive characters from the
* input until something other than FST_ERR or FST_HUH is returned, at which
* point things are resynchronized.
*
* A FST_SYX return means that between pos and end are from 1 to 3
* bytes of a system exclusive message. A SysEx message will be delivered in
* one or more chunks of that form, where the first begins with 0xf0 and the
* last (which is the only one that might have length < 3) ends with 0xf7.
*
* Messages corrupted by a protocol error are discarded and won't be seen at
* all; again SysEx is the exception, as one or more chunks of it may already
* have been parsed.
*
* For FST_CHN messages, s->msg[0] always contains the status byte even if
* FST_COMPR form was requested (pos then points to msg[1]). That way, the
* caller can always identify the exact message if there is a need to do so.
* For all other message types except FST_SYX, the status byte is at *pos
* (which may not necessarily be msg[0]!). There is only one SysEx status
* byte, so the return value FST_SYX is sufficient to identify it.
*
* To simplify some use cases, compression can also be requested with
* form=FST_VCOMP. In this form a compressible channel message is indicated
* by returning a classification of FST_CHV instead of FST_CHN, and pos points
* to the status byte rather than being advanced past it. If the caller in this
* case saves the bytes from pos to end, it will have saved the entire message,
* and can act on the FST_CHV tag to drop the first byte later. In this form,
* unlike FST_CANON, hidden note-off (i.e. note-on with velocity 0) may occur.
*
* Two obscure points in the MIDI protocol complicate things further, both to
* do with the EndSysEx code, 0xf7. First, this code is permitted (and
* meaningless) outside of a System Exclusive message, anywhere a status byte
* could appear. Second, it is allowed to be absent at the end of a System
* Exclusive message (!) - any status byte at all (non-realtime) is allowed to
* terminate the message. Both require accommodation in the interface to
* midi_fst's caller. A stray 0xf7 should be ignored BUT should count as a
* message received for purposes of Active Sense timeout; the case is
* represented by a return of FST_COM with a length of zero (pos == end). A
* status byte other than 0xf7 during a system exclusive message will cause an
* FST_SXP (sysex plus) return; the bytes from pos to end are the end of the
* system exclusive message, and after handling those the caller should call
* midi_fst again with the same input byte.
*
* midi(4) will never produce either such form of rubbish.
*/
static enum fst_ret
midi_fst(struct midi_state *s, u_char c, enum fst_form form)
{
       int syxpos = 0;

       if (c >= 0xf8) { /* All realtime messages bypass state machine */
               if (c == 0xf9 || c == 0xfd) {
                       DPRINTF( ("midi_fst: s=%p c=0x%02x undefined\n",
                           s, c));
                       s->bytesDiscarded.ev_count++;
                       return FST_ERR;
               }
               DPRINTFN(9, ("midi_fst: s=%p System Real-Time data=0x%02x\n",
                   s, c));
               s->msg[2] = c;
               FST_RETURN(2,3,FST_RT);
       }

       DPRINTFN(4, ("midi_fst: s=%p data=0x%02x state=%d\n",
           s, c, s->state));

       switch (s->state | MIDI_CAT(c)) { /* break ==> return FST_MORE */
       case MIDI_IN_START  | MIDI_CAT_COMMON:
       case MIDI_IN_RUN1_1 | MIDI_CAT_COMMON:
       case MIDI_IN_RUN2_2 | MIDI_CAT_COMMON:
       case MIDI_IN_RXX2_2 | MIDI_CAT_COMMON:
               s->msg[0] = c;
               switch ( c) {
               case 0xf0: s->state = MIDI_IN_SYX1_3; break;
               case 0xf1: s->state = MIDI_IN_COM0_1; break;
               case 0xf2: s->state = MIDI_IN_COM0_2; break;
               case 0xf3: s->state = MIDI_IN_COM0_1; break;
               case 0xf6: s->state = MIDI_IN_START;  FST_RETURN(0,1,FST_COM);
               case 0xf7: s->state = MIDI_IN_START;  FST_RETURN(0,0,FST_COM);
               default: goto protocol_violation;
               }
               break;

       case MIDI_IN_RUN1_1 | MIDI_CAT_STATUS1:
               if (c == s->msg[0]) {
                       s->state = MIDI_IN_RNX0_1;
                       break;
               }
               /* FALLTHROUGH */
       case MIDI_IN_RUN2_2 | MIDI_CAT_STATUS1:
       case MIDI_IN_RXX2_2 | MIDI_CAT_STATUS1:
       case MIDI_IN_START  | MIDI_CAT_STATUS1:
               s->state = MIDI_IN_RUN0_1;
               s->msg[0] = c;
               break;

       case MIDI_IN_RUN2_2 | MIDI_CAT_STATUS2:
       case MIDI_IN_RXX2_2 | MIDI_CAT_STATUS2:
               if (c == s->msg[0]) {
                       s->state = MIDI_IN_RNX0_2;
                       break;
               }
               if ((c ^ s->msg[0]) == 0x10 && (c & 0xe0) == 0x80) {
                       s->state = MIDI_IN_RXX0_2;
                       s->msg[0] = c;
                       break;
               }
               /* FALLTHROUGH */
       case MIDI_IN_RUN1_1 | MIDI_CAT_STATUS2:
       case MIDI_IN_START  | MIDI_CAT_STATUS2:
               s->state = MIDI_IN_RUN0_2;
               s->msg[0] = c;
               break;

       case MIDI_IN_COM0_1 | MIDI_CAT_DATA:
               s->state = MIDI_IN_START;
               s->msg[1] = c;
               FST_RETURN(0,2,FST_COM);

       case MIDI_IN_COM0_2 | MIDI_CAT_DATA:
               s->state = MIDI_IN_COM1_2;
               s->msg[1] = c;
               break;

       case MIDI_IN_COM1_2 | MIDI_CAT_DATA:
               s->state = MIDI_IN_START;
               s->msg[2] = c;
               FST_RETURN(0,3,FST_COM);

       case MIDI_IN_RUN0_1 | MIDI_CAT_DATA:
               s->state = MIDI_IN_RUN1_1;
               s->msg[1] = c;
               FST_RETURN(0,2,FST_CHN);

       case MIDI_IN_RUN1_1 | MIDI_CAT_DATA:
       case MIDI_IN_RNX0_1 | MIDI_CAT_DATA:
               s->state = MIDI_IN_RUN1_1;
               s->msg[1] = c;
               FST_CRETURN(2);

       case MIDI_IN_RUN0_2 | MIDI_CAT_DATA:
               s->state = MIDI_IN_RUN1_2;
               s->msg[1] = c;
               break;

       case MIDI_IN_RUN1_2 | MIDI_CAT_DATA:
               if (FST_CANON == form && 0 == c && (s->msg[0]&0xf0) == 0x90) {
                       s->state = MIDI_IN_RXX2_2;
                       s->msg[0] ^= 0x10;
                       s->msg[2] = 64;
               } else {
                       s->state = MIDI_IN_RUN2_2;
                       s->msg[2] = c;
               }
               FST_RETURN(0,3,FST_CHN);

       case MIDI_IN_RUN2_2 | MIDI_CAT_DATA:
               s->state = MIDI_IN_RNX1_2;
               s->msg[1] = c;
               break;

       case MIDI_IN_RXX2_2 | MIDI_CAT_DATA:
               s->state = MIDI_IN_RXX1_2;
               s->msg[0] ^= 0x10;
               s->msg[1] = c;
               break;

       case MIDI_IN_RNX0_2 | MIDI_CAT_DATA:
               s->state = MIDI_IN_RNY1_2;
               s->msg[1] = c;
               break;

       case MIDI_IN_RXX0_2 | MIDI_CAT_DATA:
               s->state = MIDI_IN_RXY1_2;
               s->msg[1] = c;
               break;

       case MIDI_IN_RNX1_2 | MIDI_CAT_DATA:
       case MIDI_IN_RNY1_2 | MIDI_CAT_DATA:
               if (FST_CANON == form && 0 == c && (s->msg[0]&0xf0) == 0x90) {
                       s->state = MIDI_IN_RXX2_2;
                       s->msg[0] ^= 0x10;
                       s->msg[2] = 64;
                       FST_RETURN(0,3,FST_CHN);
               }
               s->state = MIDI_IN_RUN2_2;
               s->msg[2] = c;
               FST_CRETURN(3);

       case MIDI_IN_RXX1_2 | MIDI_CAT_DATA:
       case MIDI_IN_RXY1_2 | MIDI_CAT_DATA:
               if (( 0 == c && (s->msg[0]&0xf0) == 0x90)
                 || (64 == c && (s->msg[0]&0xf0) == 0x80
                     && FST_CANON != form)) {
                       s->state = MIDI_IN_RXX2_2;
                       s->msg[0] ^= 0x10;
                       s->msg[2] = 64 - c;
                       FST_CRETURN(3);
               }
               s->state = MIDI_IN_RUN2_2;
               s->msg[2] = c;
               FST_RETURN(0,3,FST_CHN);

       case MIDI_IN_SYX1_3 | MIDI_CAT_DATA:
               s->state = MIDI_IN_SYX2_3;
               s->msg[1] = c;
               break;

       case MIDI_IN_SYX2_3 | MIDI_CAT_DATA:
               s->state = MIDI_IN_SYX0_3;
               s->msg[2] = c;
               FST_RETURN(0,3,FST_SYX);

       case MIDI_IN_SYX0_3 | MIDI_CAT_DATA:
               s->state = MIDI_IN_SYX1_3;
               s->msg[0] = c;
               break;

       case MIDI_IN_SYX2_3 | MIDI_CAT_COMMON:
       case MIDI_IN_SYX2_3 | MIDI_CAT_STATUS1:
       case MIDI_IN_SYX2_3 | MIDI_CAT_STATUS2:
               ++ syxpos;
               /* FALLTHROUGH */
       case MIDI_IN_SYX1_3 | MIDI_CAT_COMMON:
       case MIDI_IN_SYX1_3 | MIDI_CAT_STATUS1:
       case MIDI_IN_SYX1_3 | MIDI_CAT_STATUS2:
               ++ syxpos;
               /* FALLTHROUGH */
       case MIDI_IN_SYX0_3 | MIDI_CAT_COMMON:
       case MIDI_IN_SYX0_3 | MIDI_CAT_STATUS1:
       case MIDI_IN_SYX0_3 | MIDI_CAT_STATUS2:
               s->state = MIDI_IN_START;
               if (c == 0xf7) {
                       s->msg[syxpos] = c;
                       FST_RETURN(0,1+syxpos,FST_SYX);
               }
               s->msg[syxpos] = 0xf7;
               FST_RETURN(0,1+syxpos,FST_SXP);

       default:
protocol_violation:
               DPRINTF(("midi_fst: unexpected %#02x in state %u\n",
                   c, s->state));
               switch ( s->state) {
               case MIDI_IN_RUN1_1: /* can only get here by seeing an */
               case MIDI_IN_RUN2_2: /* INVALID System Common message */
               case MIDI_IN_RXX2_2:
                       s->state = MIDI_IN_START;
                       /* FALLTHROUGH */
               case MIDI_IN_START:
                       s->bytesDiscarded.ev_count++;
                       return FST_ERR;
               case MIDI_IN_COM1_2:
               case MIDI_IN_RUN1_2:
               case MIDI_IN_RNY1_2:
               case MIDI_IN_RXY1_2:
                       s->bytesDiscarded.ev_count++;
                       /* FALLTHROUGH */
               case MIDI_IN_COM0_1:
               case MIDI_IN_RUN0_1:
               case MIDI_IN_RNX0_1:
               case MIDI_IN_COM0_2:
               case MIDI_IN_RUN0_2:
               case MIDI_IN_RNX0_2:
               case MIDI_IN_RXX0_2:
               case MIDI_IN_RNX1_2:
               case MIDI_IN_RXX1_2:
                       s->bytesDiscarded.ev_count++;
                       s->incompleteMessages.ev_count++;
                       break;
               default:
                       DPRINTF(("midi_fst: mishandled %#02x(%u) in state %u?!\n",
                           c, MIDI_CAT(c), s->state));
                       break;
               }
               s->state = MIDI_IN_START;
               return FST_HUH;
       }
       return FST_MORE;
}

static void
midi_softint(void *cookie)
{
       struct midi_softc *sc;
       proc_t *p;
       pid_t pid;

       sc = cookie;

       mutex_enter(&proc_lock);
       pid = sc->async;
       if (pid != 0 && (p = proc_find(pid)) != NULL)
               psignal(p, SIGIO);
       mutex_exit(&proc_lock);
}

static void
midi_in(void *addr, int data)
{
       struct midi_softc *sc;
       struct midi_buffer *mb;
       int i, count;
       enum fst_ret got;
       MIDI_BUF_DECLARE(idx);
       MIDI_BUF_DECLARE(buf);

       sc = addr;
       mb = &sc->inbuf;

       KASSERT(mutex_owned(sc->lock));

       if (!sc->isopen)
               return;

       if ((sc->flags & FREAD) == 0)
               return;         /* discard data if not reading */

sxp_again:
       do {
               got = midi_fst(&sc->rcv, data, FST_CANON);
       } while (got == FST_HUH);

       switch (got) {
       case FST_MORE:
       case FST_ERR:
               return;
       case FST_CHN:
       case FST_COM:
       case FST_RT:
#if NSEQUENCER > 0
               if (sc->seqopen) {
                       extern void midiseq_in(struct midi_dev *,u_char *,int);
                       count = sc->rcv.end - sc->rcv.pos;
                       midiseq_in(sc->seq_md, sc->rcv.pos, count);
                       return;
               }
#endif
               /*
                * Pass Active Sense to the sequencer if it's open, but not to
                * a raw reader. (Really should do something intelligent with
                * it then, though....)
                */
               if (got == FST_RT && MIDI_ACK == sc->rcv.pos[0]) {
                       if (!sc->rcv_expect_asense) {
                               sc->rcv_expect_asense = 1;
                               callout_schedule(&sc->rcv_asense_co,
                                   MIDI_RCV_ASENSE_PERIOD);
                       }
                       sc->rcv_quiescent = 0;
                       sc->rcv_eof = 0;
                       return;
               }
               /* FALLTHROUGH */
       /*
        * Ultimately SysEx msgs should be offered to the sequencer also; the
        * sequencer API addresses them - but maybe our sequencer can't handle
        * them yet, so offer only to raw reader. (Which means, ultimately,
        * discard them if the sequencer's open, as it's not doing reads!)
        * -> When SysEx support is added to the sequencer, be sure to handle
        *    FST_SXP there too.
        */
       case FST_SYX:
       case FST_SXP:
               count = sc->rcv.end - sc->rcv.pos;
               sc->rcv_quiescent = 0;
               sc->rcv_eof = 0;
               if (0 == count)
                       break;
               MIDI_BUF_PRODUCER_INIT(mb,idx);
               MIDI_BUF_PRODUCER_INIT(mb,buf);
               if (count > buf_lim - buf_cur
                    || 1 > idx_lim - idx_cur) {
                       sc->rcv.bytesDiscarded.ev_count += count;
                       DPRINTF(("midi_in: buffer full, discard data=0x%02x\n",
                                sc->rcv.pos[0]));
                       return;
               }
               for (i = 0; i < count; i++) {
                       *buf_cur++ = sc->rcv.pos[i];
                       MIDI_BUF_WRAP(buf);
               }
               *idx_cur++ = PACK_MB_IDX(got,count);
               MIDI_BUF_WRAP(idx);
               MIDI_BUF_PRODUCER_WBACK(mb,buf);
               MIDI_BUF_PRODUCER_WBACK(mb,idx);
               cv_broadcast(&sc->rchan);
               selnotify(&sc->rsel, 0, NOTE_SUBMIT);
               if (sc->async != 0)
                       softint_schedule(sc->sih);
               break;
       default: /* don't #ifdef this away, gcc will say FST_HUH not handled */
               printf("midi_in: midi_fst returned %d?!\n", got);
       }
       if (FST_SXP == got)
               goto sxp_again;
}

static void
midi_out(void *addr)
{
       struct midi_softc *sc = addr;

       KASSERT(mutex_owned(sc->lock));

       if (!sc->isopen)
               return;
       DPRINTFN(8, ("midi_out: %p\n", sc));
       midi_intr_out(sc);
}

static int
midiopen(dev_t dev, int flags, int ifmt, struct lwp *l)
{
       struct midi_softc *sc;
       const struct midi_hw_if *hw;
       int error;

       sc = device_lookup_private(&midi_cd, MIDIUNIT(dev));
       if (sc == NULL)
               return (ENXIO);
       DPRINTFN(3,("midiopen %p\n", sc));

       mutex_enter(sc->lock);
       if (sc->dying) {
               mutex_exit(sc->lock);
               return (EIO);
       }
       hw = sc->hw_if;
       if (hw == NULL) {
               mutex_exit(sc->lock);
               return ENXIO;
       }
       if (sc->isopen) {
               mutex_exit(sc->lock);
               return EBUSY;
       }

       /* put both state machines into known states */
       sc->rcv.state = MIDI_IN_START;
       sc->rcv.pos = sc->rcv.msg;
       sc->rcv.end = sc->rcv.msg;
       sc->xmt.state = MIDI_IN_START;
       sc->xmt.pos = sc->xmt.msg;
       sc->xmt.end = sc->xmt.msg;

       /* copy error counters so an ioctl (TBA) can give since-open stats */
       sc->rcv.atOpen.bytesDiscarded  = sc->rcv.bytesDiscarded.ev_count;
       sc->rcv.atQuery.bytesDiscarded = sc->rcv.bytesDiscarded.ev_count;

       sc->xmt.atOpen.bytesDiscarded  = sc->xmt.bytesDiscarded.ev_count;
       sc->xmt.atQuery.bytesDiscarded = sc->xmt.bytesDiscarded.ev_count;

       /* and the buffers */
       midi_initbuf(&sc->outbuf);
       midi_initbuf(&sc->inbuf);

       /* and the receive flags */
       sc->rcv_expect_asense = 0;
       sc->rcv_quiescent = 0;
       sc->rcv_eof = 0;
       sc->isopen++;
       sc->flags = flags;
       sc->pbus = 0;
       sc->async = 0;

#ifdef MIDI_SAVE
       if (midicnt != 0) {
               midisave.cnt = midicnt;
               midicnt = 0;
       }
#endif

       error = hw->open(sc->hw_hdl, flags, midi_in, midi_out, sc);
       if (error) {
               mutex_exit(sc->lock);
               return error;
       }

       mutex_exit(sc->lock);
       return 0;
}

static int
midiclose(dev_t dev, int flags, int ifmt, struct lwp *l)
{
       struct midi_softc *sc;
       const struct midi_hw_if *hw;

       sc = device_lookup_private(&midi_cd, MIDIUNIT(dev));
       hw = sc->hw_if;

       DPRINTFN(3,("midiclose %p\n", sc));

       mutex_enter(sc->lock);
       /* midi_start_output(sc); anything buffered => pbus already set! */
       while (sc->pbus) {
               if (sc->dying)
                       break;
               DPRINTFN(8,("midiclose sleep ...\n"));
               cv_wait(&sc->wchan, sc->lock);
       }
       sc->isopen = 0;
       callout_halt(&sc->xmt_asense_co, sc->lock);
       callout_halt(&sc->rcv_asense_co, sc->lock);
       hw->close(sc->hw_hdl);
       sc->seqopen = 0;
       sc->seq_md = 0;
       mutex_exit(sc->lock);

       return 0;
}

static int
midiread(dev_t dev, struct uio *uio, int ioflag)
{
       struct midi_softc *sc;
       struct midi_buffer *mb;
       int appetite, error, first;
       MIDI_BUF_DECLARE(idx);
       MIDI_BUF_DECLARE(buf);

       sc = device_lookup_private(&midi_cd, MIDIUNIT(dev));
       mb = &sc->inbuf;
       first = 1;

       DPRINTFN(6,("midiread: %p, count=%lu\n", sc,
           (unsigned long)uio->uio_resid));

       mutex_enter(sc->lock);
       if (sc->dying) {
               mutex_exit(sc->lock);
               return EIO;
       }
       if ((sc->props & MIDI_PROP_CAN_INPUT) == 0) {
               mutex_exit(sc->lock);
               return ENXIO;
       }
       MIDI_BUF_CONSUMER_INIT(mb,idx);
       MIDI_BUF_CONSUMER_INIT(mb,buf);
       error = 0;
       for (;;) {
               /*
                * If the used portion of idx wraps around the end, just take
                * the first part on this iteration, and we'll get the rest on
                * the next.
                */
               if (idx_lim > idx_end)
                       idx_lim = idx_end;
               /*
                * Count bytes through the last complete message that will
                * fit in the requested read.
                */
               for (appetite = uio->uio_resid; idx_cur < idx_lim; ++idx_cur) {
                       if (appetite < MB_IDX_LEN(*idx_cur))
                               break;
                       appetite -= MB_IDX_LEN(*idx_cur);
               }
               appetite = uio->uio_resid - appetite;

               /*
                * Only if the read is too small to hold even the first
                * complete message will we return a partial one (updating idx
                * to reflect the remaining length of the message).
                */
               if (appetite == 0 && idx_cur < idx_lim) {
                       if (!first)
                               break;
                       appetite = uio->uio_resid;
                       *idx_cur = PACK_MB_IDX(MB_IDX_CAT(*idx_cur),
                           MB_IDX_LEN(*idx_cur) - appetite);
               }
               KASSERT(buf_cur + appetite <= buf_lim);

               /* move the bytes */
               if (appetite > 0) {
                       first = 0;  /* we know we won't return empty-handed */
                       /* do two uiomoves if data wrap around end of buf */
                       if (buf_cur + appetite > buf_end) {
                               DPRINTFN(8,
                                       ("midiread: uiomove cc=%td (prewrap)\n",
                                       buf_end - buf_cur));
                               mutex_exit(sc->lock);
                               error = uiomove(buf_cur, buf_end - buf_cur, uio);
                               mutex_enter(sc->lock);
                               if (error)
                                       break;
                               if (sc->dying) {
                                       error = EIO;
                                       break;
                               }
                               appetite -= buf_end - buf_cur;
                               buf_cur = mb->buf;
                       }
                       DPRINTFN(8, ("midiread: uiomove cc=%d\n", appetite));
                       mutex_exit(sc->lock);
                       error = uiomove(buf_cur, appetite, uio);
                       mutex_enter(sc->lock);
                       if (error)
                               break;
                       if (sc->dying) {
                               error = EIO;
                               break;
                       }
                       buf_cur += appetite;
               }

               MIDI_BUF_WRAP(idx);
               MIDI_BUF_WRAP(buf);
               MIDI_BUF_CONSUMER_WBACK(mb,idx);
               MIDI_BUF_CONSUMER_WBACK(mb,buf);
               if (0 == uio->uio_resid) /* if read satisfied, we're done */
                       break;
               MIDI_BUF_CONSUMER_REFRESH(mb,idx);
               if (idx_cur == idx_lim) { /* need to wait for data? */
                       if (!first || sc->rcv_eof) /* never block reader if */
                               break;            /* any data already in hand */
                       if (ioflag & IO_NDELAY) {
                               error = EWOULDBLOCK;
                               break;
                       }
                       error = cv_wait_sig(&sc->rchan, sc->lock);
                       if (error)
                               break;
                       MIDI_BUF_CONSUMER_REFRESH(mb,idx); /* what'd we get? */
               }
               MIDI_BUF_CONSUMER_REFRESH(mb,buf);
               if (sc->dying) {
                       error = EIO;
                       break;
               }
       }
       mutex_exit(sc->lock);

       return error;
}

static void
midi_rcv_asense(void *arg)
{
       struct midi_softc *sc;

       sc = arg;

       mutex_enter(sc->lock);
       if (sc->dying || !sc->isopen) {
               mutex_exit(sc->lock);
               return;
       }
       if (sc->rcv_quiescent) {
               sc->rcv_eof = 1;
               sc->rcv_quiescent = 0;
               sc->rcv_expect_asense = 0;
               cv_broadcast(&sc->rchan);
               selnotify(&sc->rsel, 0, NOTE_SUBMIT);
               if (sc->async)
                       softint_schedule(sc->sih);
               mutex_exit(sc->lock);
               return;
       }
       sc->rcv_quiescent = 1;
       callout_schedule(&sc->rcv_asense_co, MIDI_RCV_ASENSE_PERIOD);
       mutex_exit(sc->lock);
}

static void
midi_xmt_asense(void *arg)
{
       struct midi_softc *sc;
       int error, armed;

       sc = arg;

       mutex_enter(sc->lock);
       if (sc->pbus || sc->dying || !sc->isopen) {
               mutex_exit(sc->lock);
               return;
       }
       sc->pbus = 1;
       if (sc->props & MIDI_PROP_OUT_INTR) {
               error = sc->hw_if->output(sc->hw_hdl, MIDI_ACK);
               armed = (error == 0);
       } else {
               error = sc->hw_if->output(sc->hw_hdl, MIDI_ACK);
               armed = 0;
       }
       if (!armed) {
               sc->pbus = 0;
               callout_schedule(&sc->xmt_asense_co, MIDI_XMT_ASENSE_PERIOD);
       }
       mutex_exit(sc->lock);
}

/*
* The way this function was hacked up to plug into poll_out and intr_out
* after they were written won't win it any beauty contests, but it'll work
* (code in haste, refactor at leisure).
*/
static int
midi_msg_out(struct midi_softc *sc, u_char **idx, u_char **idxl, u_char **buf,
            u_char **bufl)
{
       MIDI_BUF_DECLARE(idx);
       MIDI_BUF_DECLARE(buf);
       MIDI_BUF_EXTENT_INIT(&sc->outbuf,idx);
       MIDI_BUF_EXTENT_INIT(&sc->outbuf,buf);
       int length;
       int error;
       u_char contig[3];
       u_char *cp;
       u_char *ep;

       KASSERT(mutex_owned(sc->lock));

       idx_cur = *idx;
       idx_lim = *idxl;
       buf_cur = *buf;
       buf_lim = *bufl;

       length = MB_IDX_LEN(*idx_cur);

       for ( cp = contig, ep = cp + length; cp < ep;) {
               *cp++ = *buf_cur++;
               MIDI_BUF_WRAP(buf);
       }
       cp = contig;

       switch ( MB_IDX_CAT(*idx_cur)) {
       case FST_CHV: /* chnmsg to be compressed (for device that wants it) */
               ++ cp;
               -- length;
               /* FALLTHROUGH */
       case FST_CHN:
               error = sc->hw_if_ext->channel(sc->hw_hdl,
                   MIDI_GET_STATUS(contig[0]), MIDI_GET_CHAN(contig[0]),
                   cp, length);
               break;
       case FST_COM:
               error = sc->hw_if_ext->common(sc->hw_hdl,
                   MIDI_GET_STATUS(contig[0]), cp, length);
               break;
       case FST_SYX:
       case FST_SXP:
               error = sc->hw_if_ext->sysex(sc->hw_hdl, cp, length);
               break;
       case FST_RT:
               error = sc->hw_if->output(sc->hw_hdl, *cp);
               break;
       default:
               error = EIO;
       }

       if (!error) {
               ++ idx_cur;
               MIDI_BUF_WRAP(idx);
               *idx  = idx_cur;
               *idxl = idx_lim;
               *buf  = buf_cur;
               *bufl = buf_lim;
       }

       return error;
}

/*
* midi_poll_out is intended for the midi hw (the vast majority of MIDI UARTs
* on sound cards, apparently) that _do not have transmit-ready interrupts_.
* Every call to hw_if->output for one of these may busy-wait to output the
* byte; at the standard midi data rate that'll be 320us per byte. The
* technique of writing only MIDI_MAX_WRITE bytes in a row and then waiting
* for MIDI_WAIT does not reduce the total time spent busy-waiting, and it
* adds arbitrary delays in transmission (and, since MIDI_WAIT is roughly the
* same as the time to send MIDI_MAX_WRITE bytes, it effectively halves the
* data rate). Here, a somewhat bolder approach is taken. Since midi traffic
* is bursty but time-sensitive--most of the time there will be none at all,
* but when there is it should go out ASAP--the strategy is to just get it
* over with, and empty the buffer in one go. The effect this can have on
* the rest of the system will be limited by the size of the buffer and the
* sparseness of the traffic. But some precautions are in order. Interrupts
* should all be unmasked when this is called, and midiwrite should not fill
* the buffer more than once (when MIDI_PROP_CAN_INTR is false) without a
* yield() so some other process can get scheduled. If the write is nonblocking,
* midiwrite should return a short count rather than yield.
*
* Someday when there is fine-grained MP support, this should be reworked to
* run in a callout so the writing process really could proceed concurrently.
* But obviously where performance is a concern, interrupt-driven hardware
* such as USB midi or (apparently) clcs will always be preferable. And it
* seems (kern/32651) that many of the devices currently working in poll mode
* may really have tx interrupt capability and want only implementation; that
* ought to happen.
*/
static int
midi_poll_out(struct midi_softc *sc)
{
       struct midi_buffer *mb = &sc->outbuf;
       int error;
       int msglen;
       MIDI_BUF_DECLARE(idx);
       MIDI_BUF_DECLARE(buf);

       KASSERT(mutex_owned(sc->lock));

       error = 0;
       MIDI_BUF_CONSUMER_INIT(mb,idx);
       MIDI_BUF_CONSUMER_INIT(mb,buf);

       for (;;) {
               while (idx_cur != idx_lim) {
                       if (sc->hw_if_ext) {
                               error = midi_msg_out(sc, &idx_cur, &idx_lim,
                                   &buf_cur, &buf_lim);
                               if (error != 0) {
                                       break;
                               }
                               continue;
                       }
                       /* or, lacking hw_if_ext ... */
                       msglen = MB_IDX_LEN(*idx_cur);
                       DPRINTFN(7,("midi_poll_out: %p <- %#02x\n",
                           sc->hw_hdl, *buf_cur));
                       error = sc->hw_if->output(sc->hw_hdl, *buf_cur);
                       if (error) {
                               break;
                       }
                       buf_cur++;
                       MIDI_BUF_WRAP(buf);
                       msglen--;
                       if (msglen) {
                               *idx_cur = PACK_MB_IDX(MB_IDX_CAT(*idx_cur),
                                   msglen);
                       } else {
                               idx_cur++;
                               MIDI_BUF_WRAP(idx);
                       }
               }
               if (error != 0) {
                       break;
               }
               KASSERT(buf_cur == buf_lim);
               MIDI_BUF_CONSUMER_WBACK(mb,idx);
               MIDI_BUF_CONSUMER_WBACK(mb,buf);
               MIDI_BUF_CONSUMER_REFRESH(mb,idx); /* any more to transmit? */
               MIDI_BUF_CONSUMER_REFRESH(mb,buf);
               if (idx_lim == idx_cur)
                       break;
       }

       if (error != 0) {
               DPRINTF(("midi_poll_output error %d\n", error));
               MIDI_BUF_CONSUMER_WBACK(mb,idx);
               MIDI_BUF_CONSUMER_WBACK(mb,buf);
       }
       sc->pbus = 0;
       callout_schedule(&sc->xmt_asense_co, MIDI_XMT_ASENSE_PERIOD);
       return error;
}

/*
* The interrupt flavor acquires spl and lock once and releases at the end,
* as it expects to write only one byte or message. The interface convention
* is that if hw_if->output returns 0, it has initiated transmission and the
* completion interrupt WILL be forthcoming; if it has not returned 0, NO
* interrupt will be forthcoming, and if it returns EINPROGRESS it wants
* another byte right away.
*/
static int
midi_intr_out(struct midi_softc *sc)
{
       struct midi_buffer *mb;
       int error, msglen;
       MIDI_BUF_DECLARE(idx);
       MIDI_BUF_DECLARE(buf);
       int armed = 0;

       KASSERT(mutex_owned(sc->lock));

       error = 0;
       mb = &sc->outbuf;

       MIDI_BUF_CONSUMER_INIT(mb,idx);
       MIDI_BUF_CONSUMER_INIT(mb,buf);

       while (idx_cur != idx_lim) {
               if (sc->hw_if_ext) {
                       error = midi_msg_out(sc, &idx_cur, &idx_lim,
                           &buf_cur, &buf_lim);
                       if (!error ) /* no EINPROGRESS from extended hw_if */
                               armed = 1;
                       break;
               }
               /* or, lacking hw_if_ext ... */
               msglen = MB_IDX_LEN(*idx_cur);
               error = sc->hw_if->output(sc->hw_hdl, *buf_cur);
               if (error &&  error != EINPROGRESS)
                       break;
               ++buf_cur;
               MIDI_BUF_WRAP(buf);
               --msglen;
               if (msglen)
                       *idx_cur = PACK_MB_IDX(MB_IDX_CAT(*idx_cur),msglen);
               else {
                       ++idx_cur;
                       MIDI_BUF_WRAP(idx);
               }
               if (!error) {
                       armed = 1;
                       break;
               }
       }
       MIDI_BUF_CONSUMER_WBACK(mb,idx);
       MIDI_BUF_CONSUMER_WBACK(mb,buf);
       if (!armed) {
               sc->pbus = 0;
               callout_schedule(&sc->xmt_asense_co, MIDI_XMT_ASENSE_PERIOD);
       }
       cv_broadcast(&sc->wchan);
       selnotify(&sc->wsel, 0, NOTE_SUBMIT);
       if (sc->async) {
               softint_schedule(sc->sih);
       }
       if (error) {
               DPRINTF(("midi_intr_output error %d\n", error));
       }
       return error;
}

static int
midi_start_output(struct midi_softc *sc)
{

       KASSERT(mutex_owned(sc->lock));

       if (sc->dying)
               return EIO;
       if (sc->props & MIDI_PROP_OUT_INTR)
               return midi_intr_out(sc);
       return midi_poll_out(sc);
}

static int
real_writebytes(struct midi_softc *sc, u_char *ibuf, int cc)
{
       u_char *iend;
       struct midi_buffer *mb;
       int arming, count, got;
       enum fst_form form;
       MIDI_BUF_DECLARE(idx);
       MIDI_BUF_DECLARE(buf);
       int error;

       KASSERT(mutex_owned(sc->lock));

       if (sc->dying || !sc->isopen)
               return EIO;

       sc->refcnt++;

       iend = ibuf + cc;
       mb = &sc->outbuf;
       arming = 0;

       /*
        * If the hardware uses the extended hw_if, pass it canonicalized
        * messages (or compressed ones if it specifically requests, using
        * VCOMP form so the bottom half can still pass the op and chan along);
        * if it does not, send it compressed messages (using COMPR form as
        * there is no need to preserve the status for the bottom half).
        */
       if (NULL == sc->hw_if_ext)
               form = FST_COMPR;
       else if (sc->hw_if_ext->compress)
               form = FST_VCOMP;
       else
               form = FST_CANON;

       MIDI_BUF_PRODUCER_INIT(mb,idx);
       MIDI_BUF_PRODUCER_INIT(mb,buf);

       while (ibuf < iend) {
               got = midi_fst(&sc->xmt, *ibuf, form);
               ++ibuf;
               switch ( got) {
               case FST_MORE:
                       continue;
               case FST_ERR:
               case FST_HUH:
                       error = EPROTO;
                       goto out;
               case FST_CHN:
               case FST_CHV: /* only occurs in VCOMP form */
               case FST_COM:
               case FST_RT:
               case FST_SYX:
               case FST_SXP:
                       break; /* go add to buffer */
#if defined(AUDIO_DEBUG) || defined(DIAGNOSTIC)
               default:
                       printf("midi_wr: midi_fst returned %d?!\n", got);
#endif
               }
               count = sc->xmt.end - sc->xmt.pos;
               if (0 == count ) /* can happen with stray 0xf7; see midi_fst */
                       continue;
               /*
                * return EWOULDBLOCK if the data passed will not fit in
                * the buffer; the caller should have taken steps to avoid that.
                * If got==FST_SXP we lose the new status byte, but we're losing
                * anyway, so c'est la vie.
                */
               if (idx_cur == idx_lim || count > buf_lim - buf_cur) {
                       MIDI_BUF_PRODUCER_REFRESH(mb,idx); /* get the most */
                       MIDI_BUF_PRODUCER_REFRESH(mb,buf); /*  current facts */
                       if (idx_cur == idx_lim || count > buf_lim - buf_cur) {
                               error = EWOULDBLOCK; /* caller's problem */
                               goto out;
                       }
               }
               *idx_cur++ = PACK_MB_IDX(got,count);
               MIDI_BUF_WRAP(idx);
               while (count) {
                       *buf_cur++ = *(sc->xmt.pos)++;
                       MIDI_BUF_WRAP(buf);
                       -- count;
               }
               if (FST_SXP == got)
                       -- ibuf; /* again with same status byte */
       }
       MIDI_BUF_PRODUCER_WBACK(mb,buf);
       MIDI_BUF_PRODUCER_WBACK(mb,idx);
       /*
        * If the output transfer is not already busy, and there is a message
        * buffered, mark it busy, stop the Active Sense callout (what if we're
        * too late and it's expired already? No big deal, an extra Active Sense
        * never hurt anybody) and start the output transfer once we're out of
        * the critical section (pbus==1 will stop anyone else doing the same).
        */
       MIDI_BUF_CONSUMER_INIT(mb,idx); /* check what consumer's got to read */
       if (!sc->pbus && idx_cur < idx_lim) {
               sc->pbus = 1;
               callout_stop(&sc->xmt_asense_co);
               arming = 1;
       }

       error = arming ? midi_start_output(sc) : 0;

out:
       if (--sc->refcnt < 0)
               cv_broadcast(&sc->detach_cv);

       return error;
}

static int
midiwrite(dev_t dev, struct uio *uio, int ioflag)
{
       struct midi_softc *sc;
       struct midi_buffer *mb;
       int error;
       u_char inp[256];
       MIDI_BUF_DECLARE(idx);
       MIDI_BUF_DECLARE(buf);
       size_t idxspace;
       size_t bufspace;
       size_t xfrcount;
       int pollout = 0;

       (void)buf_end; (void)idx_end;
       sc = device_lookup_private(&midi_cd, MIDIUNIT(dev));

       DPRINTFN(6,("midiwrite: %p, unit=%d, count=%lu\n", sc, (int)minor(dev),
           (unsigned long)uio->uio_resid));

       mutex_enter(sc->lock);
       if (sc->dying) {
               mutex_exit(sc->lock);
               return EIO;
       }

       sc->refcnt++;

       mb = &sc->outbuf;
       error = 0;
       while (uio->uio_resid > 0 && !error) {
               /*
                * block if necessary for the minimum buffer space to guarantee
                * we can write something.
                */
               MIDI_BUF_PRODUCER_INIT(mb,idx); /* init can't go above loop; */
               MIDI_BUF_PRODUCER_INIT(mb,buf); /* real_writebytes moves cur */
               for (;;) {
                       idxspace = MIDI_BUF_PRODUCER_REFRESH(mb,idx) - idx_cur;
                       bufspace = MIDI_BUF_PRODUCER_REFRESH(mb,buf) - buf_cur;
                       if (idxspace >= 1 && bufspace >= 3 && !pollout)
                               break;
                       DPRINTFN(8,("midi_write: sleep idx=%zd buf=%zd\n",
                                idxspace, bufspace));
                       if (ioflag & IO_NDELAY) {
                               /*
                                * If some amount has already been transferred,
                                * the common syscall code will automagically
                                * convert this to success with a short count.
                                */
                               error = EWOULDBLOCK;
                               goto out;
                       }
                       if (pollout) {
                               mutex_exit(sc->lock);
                               yield(); /* see midi_poll_output */
                               mutex_enter(sc->lock);
                               pollout = 0;
                       } else
                               error = cv_wait_sig(&sc->wchan, sc->lock);
                       if (sc->dying)
                               error = EIO;
                       if (error) {
                               /*
                                * Similarly, the common code will handle
                                * EINTR and ERESTART properly here, changing to
                                * a short count if something transferred.
                                */
                               goto out;
                       }
               }

               /*
                * The number of bytes we can safely extract from the uio
                * depends on the available idx and buf space. Worst case,
                * every byte is a message so 1 idx is required per byte.
                * Worst case, the first byte completes a 3-byte msg in prior
                * state, and every subsequent byte is a Program Change or
                * Channel Pressure msg with running status and expands to 2
                * bytes, so the buf space reqd is 3+2(n-1) or 2n+1. So limit
                * the transfer to the min of idxspace and (bufspace-1)>>1.
                */
               xfrcount = (bufspace - 1) >> 1;
               if (xfrcount > idxspace)
                       xfrcount = idxspace;
               if (xfrcount > sizeof inp)
                       xfrcount = sizeof inp;
               if (xfrcount > uio->uio_resid)
                       xfrcount = uio->uio_resid;

               mutex_exit(sc->lock);
               error = uiomove(inp, xfrcount, uio);
               mutex_enter(sc->lock);
#ifdef MIDI_DEBUG
               if (error)
                       printf("midi_write:(1) uiomove failed %d; "
                              "xfrcount=%zu inp=%p\n",
                              error, xfrcount, inp);
#endif
               if (error)
                       break;

               /*
                * The number of bytes we extracted being calculated to
                * definitely fit in the buffer even with canonicalization,
                * there is no excuse for real_writebytes to return EWOULDBLOCK.
                */
               error = real_writebytes(sc, inp, xfrcount);
               KASSERT(error != EWOULDBLOCK);
               if (error)
                       break;

               /*
                * If this is a polling device and we just sent a buffer, let's
                * not send another without giving some other process a chance.
                */
               if ((sc->props & MIDI_PROP_OUT_INTR) == 0)
                       pollout = 1;
               DPRINTFN(8,("midiwrite: uio_resid now %zu, props=%d\n",
                   uio->uio_resid, sc->props));
       }

out:
       if (--sc->refcnt < 0)
               cv_broadcast(&sc->detach_cv);

       mutex_exit(sc->lock);
       return error;
}

/*
* This write routine is only called from sequencer code and expects
* a write that is smaller than the MIDI buffer.
*/
int
midi_writebytes(int unit, u_char *bf, int cc)
{
       struct midi_softc *sc =
           device_lookup_private(&midi_cd, unit);
       int error;

       if (!sc)
               return EIO;

       DPRINTFN(7, ("midi_writebytes: %p, unit=%d, cc=%d %#02x %#02x %#02x\n",
                   sc, unit, cc, bf[0], bf[1], bf[2]));

       mutex_enter(sc->lock);
       if (sc->dying)
               error = EIO;
       else
               error = real_writebytes(sc, bf, cc);
       mutex_exit(sc->lock);

       return error;
}

static int
midiioctl(dev_t dev, u_long cmd, void *addr, int flag, struct lwp *l)
{
       struct midi_softc *sc;
       const struct midi_hw_if *hw;
       int error;
       MIDI_BUF_DECLARE(buf);

       (void)buf_end;
       sc = device_lookup_private(&midi_cd, MIDIUNIT(dev));

       mutex_enter(sc->lock);
       if (sc->dying) {
               mutex_exit(sc->lock);
               return EIO;
       }
       hw = sc->hw_if;
       error = 0;

       sc->refcnt++;

       DPRINTFN(5,("midiioctl: %p cmd=0x%08lx\n", sc, cmd));

       switch (cmd) {
       case FIONBIO:
               /* All handled in the upper layer. */
               break;

       case FIONREAD:
               /*
                * This code relies on the current implementation of midi_in
                * always updating buf and idx together in a critical section,
                * so buf always ends at a message boundary. Document this
                * ioctl as always returning a value such that the last message
                * included is complete (SysEx the only exception), and then
                * make sure the implementation doesn't regress.  NB that
                * means if this ioctl returns n and the proc then issues a
                * read of n, n bytes will be read, but if the proc issues a
                * read of m < n, fewer than m bytes may be read to ensure the
                * read ends at a message boundary.
                */
               MIDI_BUF_CONSUMER_INIT(&sc->inbuf,buf);
               *(int *)addr = buf_lim - buf_cur;
               break;

       case FIOASYNC:
               mutex_exit(sc->lock);
               mutex_enter(&proc_lock);
               if (*(int *)addr) {
                       if (sc->async) {
                               error = EBUSY;
                       } else {
                               sc->async = curproc->p_pid;
                       }
                       DPRINTFN(5,("midi_ioctl: FIOASYNC %d\n",
                           curproc->p_pid));
               } else {
                       sc->async = 0;
               }
               mutex_exit(&proc_lock);
               mutex_enter(sc->lock);
               break;

#if 0
       case MIDI_PRETIME:
               /* XXX OSS
                * This should set up a read timeout, but that's
                * why we have poll(), so there's nothing yet. */
               error = EINVAL;
               break;
#endif

#ifdef MIDI_SAVE
       case MIDI_GETSAVE:
               mutex_exit(sc->lock);
               error = copyout(&midisave, *(void **)addr, sizeof midisave);
               mutex_enter(sc->lock);
               break;
#endif

       default:
               if (hw->ioctl != NULL) {
                       error = hw->ioctl(sc->hw_hdl, cmd, addr, flag, l);
               } else {
                       error = EINVAL;
               }
               break;
       }

       if (--sc->refcnt < 0)
               cv_broadcast(&sc->detach_cv);
       mutex_exit(sc->lock);
       return error;
}

static int
midipoll(dev_t dev, int events, struct lwp *l)
{
       struct midi_softc *sc;
       int revents;
       MIDI_BUF_DECLARE(idx);
       MIDI_BUF_DECLARE(buf);

       (void)buf_end; (void)idx_end;
       sc = device_lookup_private(&midi_cd, MIDIUNIT(dev));
       revents = 0;

       DPRINTFN(6,("midipoll: %p events=0x%x\n", sc, events));

       mutex_enter(sc->lock);
       if (sc->dying) {
               mutex_exit(sc->lock);
               return POLLHUP;
       }

       sc->refcnt++;

       if ((events & (POLLIN | POLLRDNORM)) != 0) {
               MIDI_BUF_CONSUMER_INIT(&sc->inbuf, idx);
               if (idx_cur < idx_lim)
                       revents |= events & (POLLIN | POLLRDNORM);
               else
                       selrecord(l, &sc->rsel);
       }
       if ((events & (POLLOUT | POLLWRNORM)) != 0) {
               MIDI_BUF_PRODUCER_INIT(&sc->outbuf, idx);
               MIDI_BUF_PRODUCER_INIT(&sc->outbuf, buf);
               if (idx_lim - idx_cur >= 1 && buf_lim - buf_cur >= 3)
                       revents |= events & (POLLOUT | POLLWRNORM);
               else
                       selrecord(l, &sc->wsel);
       }

       if (--sc->refcnt < 0)
               cv_broadcast(&sc->detach_cv);

       mutex_exit(sc->lock);

       return revents;
}

static void
filt_midirdetach(struct knote *kn)
{
       struct midi_softc *sc = kn->kn_hook;

       mutex_enter(sc->lock);
       selremove_knote(&sc->rsel, kn);
       mutex_exit(sc->lock);
}

static int
filt_midiread(struct knote *kn, long hint)
{
       struct midi_softc *sc = kn->kn_hook;
       MIDI_BUF_DECLARE(buf);

       (void)buf_end;
       if (hint != NOTE_SUBMIT)
               mutex_enter(sc->lock);
       MIDI_BUF_CONSUMER_INIT(&sc->inbuf,buf);
       kn->kn_data = buf_lim - buf_cur;
       if (hint != NOTE_SUBMIT)
               mutex_exit(sc->lock);
       return (kn->kn_data > 0);
}

static const struct filterops midiread_filtops = {
       .f_flags = FILTEROP_ISFD,
       .f_attach = NULL,
       .f_detach = filt_midirdetach,
       .f_event = filt_midiread,
};

static void
filt_midiwdetach(struct knote *kn)
{
       struct midi_softc *sc = kn->kn_hook;

       mutex_enter(sc->lock);
       selremove_knote(&sc->wsel, kn);
       mutex_exit(sc->lock);
}

static int
filt_midiwrite(struct knote *kn, long hint)
{
       struct midi_softc *sc = kn->kn_hook;
       MIDI_BUF_DECLARE(idx);
       MIDI_BUF_DECLARE(buf);

       mutex_exit(sc->lock);
       sc->refcnt++;
       mutex_enter(sc->lock);

       (void)idx_end; (void)buf_end;
       if (hint != NOTE_SUBMIT)
               mutex_enter(sc->lock);
       MIDI_BUF_PRODUCER_INIT(&sc->outbuf,idx);
       MIDI_BUF_PRODUCER_INIT(&sc->outbuf,buf);
       kn->kn_data = ((buf_lim - buf_cur)-1)>>1;
       if (kn->kn_data > idx_lim - idx_cur)
               kn->kn_data = idx_lim - idx_cur;
       if (hint != NOTE_SUBMIT)
               mutex_exit(sc->lock);

       // XXXMRG -- move this up, avoid the relock?
       mutex_enter(sc->lock);
       if (--sc->refcnt < 0)
               cv_broadcast(&sc->detach_cv);
       mutex_exit(sc->lock);

       return (kn->kn_data > 0);
}

static const struct filterops midiwrite_filtops = {
       .f_flags = FILTEROP_ISFD,
       .f_attach = NULL,
       .f_detach = filt_midiwdetach,
       .f_event = filt_midiwrite,
};

int
midikqfilter(dev_t dev, struct knote *kn)
{
       struct midi_softc *sc =
           device_lookup_private(&midi_cd, MIDIUNIT(dev));
       struct selinfo *sip;
       int error = 0;

       mutex_enter(sc->lock);
       sc->refcnt++;

       switch (kn->kn_filter) {
       case EVFILT_READ:
               sip = &sc->rsel;
               kn->kn_fop = &midiread_filtops;
               break;

       case EVFILT_WRITE:
               sip = &sc->wsel;
               kn->kn_fop = &midiwrite_filtops;
               break;

       default:
               error = EINVAL;
               goto out;
       }

       kn->kn_hook = sc;

       selrecord_knote(sip, kn);
out:
       if (--sc->refcnt < 0)
               cv_broadcast(&sc->detach_cv);
       mutex_exit(sc->lock);

       return (error);
}

void
midi_getinfo(dev_t dev, struct midi_info *mi)
{
       struct midi_softc *sc;

       sc = device_lookup_private(&midi_cd, MIDIUNIT(dev));
       if (sc == NULL)
               return;
       mutex_enter(sc->lock);
       sc->hw_if->getinfo(sc->hw_hdl, mi);
       mutex_exit(sc->lock);
}

#elif NMIDIBUS > 0 /* but NMIDI == 0 */

void
midi_register_hw_if_ext(struct midi_hw_if_ext *exthw)
{

       /* nothing */
}

#endif /* NMIDI > 0 */

#if NMIDI > 0 || NMIDIBUS > 0

device_t
midi_attach_mi(const struct midi_hw_if *mhwp, void *hdlp, device_t dev)
{
       struct audio_attach_args arg;

       if (mhwp == NULL) {
               panic("midi_attach_mi: NULL\n");
               return (0);
       }

       arg.type = AUDIODEV_TYPE_MIDI;
       arg.hwif = mhwp;
       arg.hdl = hdlp;
       return (config_found(dev, &arg, audioprint,
                            CFARGS(.iattr = "midibus")));
}

#endif /* NMIDI > 0 || NMIDIBUS > 0 */