xref: /openbmc/qemu/audio/alsaaudio.c (revision ddda3748)
1 /*
2  * QEMU ALSA audio driver
3  *
4  * Copyright (c) 2005 Vassili Karpov (malc)
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a copy
7  * of this software and associated documentation files (the "Software"), to deal
8  * in the Software without restriction, including without limitation the rights
9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10  * copies of the Software, and to permit persons to whom the Software is
11  * furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be included in
14  * all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22  * THE SOFTWARE.
23  */
24 
25 #include "qemu/osdep.h"
26 #include <alsa/asoundlib.h>
27 #include "qemu/main-loop.h"
28 #include "qemu/module.h"
29 #include "audio.h"
30 #include "trace.h"
31 
32 #pragma GCC diagnostic ignored "-Waddress"
33 
34 #define AUDIO_CAP "alsa"
35 #include "audio_int.h"
36 
37 struct pollhlp {
38     snd_pcm_t *handle;
39     struct pollfd *pfds;
40     int count;
41     int mask;
42     AudioState *s;
43 };
44 
45 typedef struct ALSAVoiceOut {
46     HWVoiceOut hw;
47     snd_pcm_t *handle;
48     struct pollhlp pollhlp;
49     Audiodev *dev;
50 } ALSAVoiceOut;
51 
52 typedef struct ALSAVoiceIn {
53     HWVoiceIn hw;
54     snd_pcm_t *handle;
55     struct pollhlp pollhlp;
56     Audiodev *dev;
57 } ALSAVoiceIn;
58 
59 struct alsa_params_req {
60     int freq;
61     snd_pcm_format_t fmt;
62     int nchannels;
63 };
64 
65 struct alsa_params_obt {
66     int freq;
67     AudioFormat fmt;
68     int endianness;
69     int nchannels;
70     snd_pcm_uframes_t samples;
71 };
72 
73 static void GCC_FMT_ATTR (2, 3) alsa_logerr (int err, const char *fmt, ...)
74 {
75     va_list ap;
76 
77     va_start (ap, fmt);
78     AUD_vlog (AUDIO_CAP, fmt, ap);
79     va_end (ap);
80 
81     AUD_log (AUDIO_CAP, "Reason: %s\n", snd_strerror (err));
82 }
83 
84 static void GCC_FMT_ATTR (3, 4) alsa_logerr2 (
85     int err,
86     const char *typ,
87     const char *fmt,
88     ...
89     )
90 {
91     va_list ap;
92 
93     AUD_log (AUDIO_CAP, "Could not initialize %s\n", typ);
94 
95     va_start (ap, fmt);
96     AUD_vlog (AUDIO_CAP, fmt, ap);
97     va_end (ap);
98 
99     AUD_log (AUDIO_CAP, "Reason: %s\n", snd_strerror (err));
100 }
101 
102 static void alsa_fini_poll (struct pollhlp *hlp)
103 {
104     int i;
105     struct pollfd *pfds = hlp->pfds;
106 
107     if (pfds) {
108         for (i = 0; i < hlp->count; ++i) {
109             qemu_set_fd_handler (pfds[i].fd, NULL, NULL, NULL);
110         }
111         g_free (pfds);
112     }
113     hlp->pfds = NULL;
114     hlp->count = 0;
115     hlp->handle = NULL;
116 }
117 
118 static void alsa_anal_close1 (snd_pcm_t **handlep)
119 {
120     int err = snd_pcm_close (*handlep);
121     if (err) {
122         alsa_logerr (err, "Failed to close PCM handle %p\n", *handlep);
123     }
124     *handlep = NULL;
125 }
126 
127 static void alsa_anal_close (snd_pcm_t **handlep, struct pollhlp *hlp)
128 {
129     alsa_fini_poll (hlp);
130     alsa_anal_close1 (handlep);
131 }
132 
133 static int alsa_recover (snd_pcm_t *handle)
134 {
135     int err = snd_pcm_prepare (handle);
136     if (err < 0) {
137         alsa_logerr (err, "Failed to prepare handle %p\n", handle);
138         return -1;
139     }
140     return 0;
141 }
142 
143 static int alsa_resume (snd_pcm_t *handle)
144 {
145     int err = snd_pcm_resume (handle);
146     if (err < 0) {
147         alsa_logerr (err, "Failed to resume handle %p\n", handle);
148         return -1;
149     }
150     return 0;
151 }
152 
153 static void alsa_poll_handler (void *opaque)
154 {
155     int err, count;
156     snd_pcm_state_t state;
157     struct pollhlp *hlp = opaque;
158     unsigned short revents;
159 
160     count = poll (hlp->pfds, hlp->count, 0);
161     if (count < 0) {
162         dolog ("alsa_poll_handler: poll %s\n", strerror (errno));
163         return;
164     }
165 
166     if (!count) {
167         return;
168     }
169 
170     /* XXX: ALSA example uses initial count, not the one returned by
171        poll, correct? */
172     err = snd_pcm_poll_descriptors_revents (hlp->handle, hlp->pfds,
173                                             hlp->count, &revents);
174     if (err < 0) {
175         alsa_logerr (err, "snd_pcm_poll_descriptors_revents");
176         return;
177     }
178 
179     if (!(revents & hlp->mask)) {
180         trace_alsa_revents(revents);
181         return;
182     }
183 
184     state = snd_pcm_state (hlp->handle);
185     switch (state) {
186     case SND_PCM_STATE_SETUP:
187         alsa_recover (hlp->handle);
188         break;
189 
190     case SND_PCM_STATE_XRUN:
191         alsa_recover (hlp->handle);
192         break;
193 
194     case SND_PCM_STATE_SUSPENDED:
195         alsa_resume (hlp->handle);
196         break;
197 
198     case SND_PCM_STATE_PREPARED:
199         audio_run(hlp->s, "alsa run (prepared)");
200         break;
201 
202     case SND_PCM_STATE_RUNNING:
203         audio_run(hlp->s, "alsa run (running)");
204         break;
205 
206     default:
207         dolog ("Unexpected state %d\n", state);
208     }
209 }
210 
211 static int alsa_poll_helper (snd_pcm_t *handle, struct pollhlp *hlp, int mask)
212 {
213     int i, count, err;
214     struct pollfd *pfds;
215 
216     count = snd_pcm_poll_descriptors_count (handle);
217     if (count <= 0) {
218         dolog ("Could not initialize poll mode\n"
219                "Invalid number of poll descriptors %d\n", count);
220         return -1;
221     }
222 
223     pfds = audio_calloc ("alsa_poll_helper", count, sizeof (*pfds));
224     if (!pfds) {
225         dolog ("Could not initialize poll mode\n");
226         return -1;
227     }
228 
229     err = snd_pcm_poll_descriptors (handle, pfds, count);
230     if (err < 0) {
231         alsa_logerr (err, "Could not initialize poll mode\n"
232                      "Could not obtain poll descriptors\n");
233         g_free (pfds);
234         return -1;
235     }
236 
237     for (i = 0; i < count; ++i) {
238         if (pfds[i].events & POLLIN) {
239             qemu_set_fd_handler (pfds[i].fd, alsa_poll_handler, NULL, hlp);
240         }
241         if (pfds[i].events & POLLOUT) {
242             trace_alsa_pollout(i, pfds[i].fd);
243             qemu_set_fd_handler (pfds[i].fd, NULL, alsa_poll_handler, hlp);
244         }
245         trace_alsa_set_handler(pfds[i].events, i, pfds[i].fd, err);
246 
247     }
248     hlp->pfds = pfds;
249     hlp->count = count;
250     hlp->handle = handle;
251     hlp->mask = mask;
252     return 0;
253 }
254 
255 static int alsa_poll_out (HWVoiceOut *hw)
256 {
257     ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
258 
259     return alsa_poll_helper (alsa->handle, &alsa->pollhlp, POLLOUT);
260 }
261 
262 static int alsa_poll_in (HWVoiceIn *hw)
263 {
264     ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
265 
266     return alsa_poll_helper (alsa->handle, &alsa->pollhlp, POLLIN);
267 }
268 
269 static snd_pcm_format_t aud_to_alsafmt (AudioFormat fmt, int endianness)
270 {
271     switch (fmt) {
272     case AUDIO_FORMAT_S8:
273         return SND_PCM_FORMAT_S8;
274 
275     case AUDIO_FORMAT_U8:
276         return SND_PCM_FORMAT_U8;
277 
278     case AUDIO_FORMAT_S16:
279         if (endianness) {
280             return SND_PCM_FORMAT_S16_BE;
281         }
282         else {
283             return SND_PCM_FORMAT_S16_LE;
284         }
285 
286     case AUDIO_FORMAT_U16:
287         if (endianness) {
288             return SND_PCM_FORMAT_U16_BE;
289         }
290         else {
291             return SND_PCM_FORMAT_U16_LE;
292         }
293 
294     case AUDIO_FORMAT_S32:
295         if (endianness) {
296             return SND_PCM_FORMAT_S32_BE;
297         }
298         else {
299             return SND_PCM_FORMAT_S32_LE;
300         }
301 
302     case AUDIO_FORMAT_U32:
303         if (endianness) {
304             return SND_PCM_FORMAT_U32_BE;
305         }
306         else {
307             return SND_PCM_FORMAT_U32_LE;
308         }
309 
310     case AUDIO_FORMAT_F32:
311         if (endianness) {
312             return SND_PCM_FORMAT_FLOAT_BE;
313         } else {
314             return SND_PCM_FORMAT_FLOAT_LE;
315         }
316 
317     default:
318         dolog ("Internal logic error: Bad audio format %d\n", fmt);
319 #ifdef DEBUG_AUDIO
320         abort ();
321 #endif
322         return SND_PCM_FORMAT_U8;
323     }
324 }
325 
326 static int alsa_to_audfmt (snd_pcm_format_t alsafmt, AudioFormat *fmt,
327                            int *endianness)
328 {
329     switch (alsafmt) {
330     case SND_PCM_FORMAT_S8:
331         *endianness = 0;
332         *fmt = AUDIO_FORMAT_S8;
333         break;
334 
335     case SND_PCM_FORMAT_U8:
336         *endianness = 0;
337         *fmt = AUDIO_FORMAT_U8;
338         break;
339 
340     case SND_PCM_FORMAT_S16_LE:
341         *endianness = 0;
342         *fmt = AUDIO_FORMAT_S16;
343         break;
344 
345     case SND_PCM_FORMAT_U16_LE:
346         *endianness = 0;
347         *fmt = AUDIO_FORMAT_U16;
348         break;
349 
350     case SND_PCM_FORMAT_S16_BE:
351         *endianness = 1;
352         *fmt = AUDIO_FORMAT_S16;
353         break;
354 
355     case SND_PCM_FORMAT_U16_BE:
356         *endianness = 1;
357         *fmt = AUDIO_FORMAT_U16;
358         break;
359 
360     case SND_PCM_FORMAT_S32_LE:
361         *endianness = 0;
362         *fmt = AUDIO_FORMAT_S32;
363         break;
364 
365     case SND_PCM_FORMAT_U32_LE:
366         *endianness = 0;
367         *fmt = AUDIO_FORMAT_U32;
368         break;
369 
370     case SND_PCM_FORMAT_S32_BE:
371         *endianness = 1;
372         *fmt = AUDIO_FORMAT_S32;
373         break;
374 
375     case SND_PCM_FORMAT_U32_BE:
376         *endianness = 1;
377         *fmt = AUDIO_FORMAT_U32;
378         break;
379 
380     case SND_PCM_FORMAT_FLOAT_LE:
381         *endianness = 0;
382         *fmt = AUDIO_FORMAT_F32;
383         break;
384 
385     case SND_PCM_FORMAT_FLOAT_BE:
386         *endianness = 1;
387         *fmt = AUDIO_FORMAT_F32;
388         break;
389 
390     default:
391         dolog ("Unrecognized audio format %d\n", alsafmt);
392         return -1;
393     }
394 
395     return 0;
396 }
397 
398 static void alsa_dump_info (struct alsa_params_req *req,
399                             struct alsa_params_obt *obt,
400                             snd_pcm_format_t obtfmt,
401                             AudiodevAlsaPerDirectionOptions *apdo)
402 {
403     dolog("parameter | requested value | obtained value\n");
404     dolog("format    |      %10d |     %10d\n", req->fmt, obtfmt);
405     dolog("channels  |      %10d |     %10d\n",
406           req->nchannels, obt->nchannels);
407     dolog("frequency |      %10d |     %10d\n", req->freq, obt->freq);
408     dolog("============================================\n");
409     dolog("requested: buffer len %" PRId32 " period len %" PRId32 "\n",
410           apdo->buffer_length, apdo->period_length);
411     dolog("obtained: samples %ld\n", obt->samples);
412 }
413 
414 static void alsa_set_threshold (snd_pcm_t *handle, snd_pcm_uframes_t threshold)
415 {
416     int err;
417     snd_pcm_sw_params_t *sw_params;
418 
419     snd_pcm_sw_params_alloca (&sw_params);
420 
421     err = snd_pcm_sw_params_current (handle, sw_params);
422     if (err < 0) {
423         dolog ("Could not fully initialize DAC\n");
424         alsa_logerr (err, "Failed to get current software parameters\n");
425         return;
426     }
427 
428     err = snd_pcm_sw_params_set_start_threshold (handle, sw_params, threshold);
429     if (err < 0) {
430         dolog ("Could not fully initialize DAC\n");
431         alsa_logerr (err, "Failed to set software threshold to %ld\n",
432                      threshold);
433         return;
434     }
435 
436     err = snd_pcm_sw_params (handle, sw_params);
437     if (err < 0) {
438         dolog ("Could not fully initialize DAC\n");
439         alsa_logerr (err, "Failed to set software parameters\n");
440         return;
441     }
442 }
443 
444 static int alsa_open(bool in, struct alsa_params_req *req,
445                      struct alsa_params_obt *obt, snd_pcm_t **handlep,
446                      Audiodev *dev)
447 {
448     AudiodevAlsaOptions *aopts = &dev->u.alsa;
449     AudiodevAlsaPerDirectionOptions *apdo = in ? aopts->in : aopts->out;
450     snd_pcm_t *handle;
451     snd_pcm_hw_params_t *hw_params;
452     int err;
453     unsigned int freq, nchannels;
454     const char *pcm_name = apdo->has_dev ? apdo->dev : "default";
455     snd_pcm_uframes_t obt_buffer_size;
456     const char *typ = in ? "ADC" : "DAC";
457     snd_pcm_format_t obtfmt;
458 
459     freq = req->freq;
460     nchannels = req->nchannels;
461 
462     snd_pcm_hw_params_alloca (&hw_params);
463 
464     err = snd_pcm_open (
465         &handle,
466         pcm_name,
467         in ? SND_PCM_STREAM_CAPTURE : SND_PCM_STREAM_PLAYBACK,
468         SND_PCM_NONBLOCK
469         );
470     if (err < 0) {
471         alsa_logerr2 (err, typ, "Failed to open `%s':\n", pcm_name);
472         return -1;
473     }
474 
475     err = snd_pcm_hw_params_any (handle, hw_params);
476     if (err < 0) {
477         alsa_logerr2 (err, typ, "Failed to initialize hardware parameters\n");
478         goto err;
479     }
480 
481     err = snd_pcm_hw_params_set_access (
482         handle,
483         hw_params,
484         SND_PCM_ACCESS_RW_INTERLEAVED
485         );
486     if (err < 0) {
487         alsa_logerr2 (err, typ, "Failed to set access type\n");
488         goto err;
489     }
490 
491     err = snd_pcm_hw_params_set_format (handle, hw_params, req->fmt);
492     if (err < 0) {
493         alsa_logerr2 (err, typ, "Failed to set format %d\n", req->fmt);
494     }
495 
496     err = snd_pcm_hw_params_set_rate_near (handle, hw_params, &freq, 0);
497     if (err < 0) {
498         alsa_logerr2 (err, typ, "Failed to set frequency %d\n", req->freq);
499         goto err;
500     }
501 
502     err = snd_pcm_hw_params_set_channels_near (
503         handle,
504         hw_params,
505         &nchannels
506         );
507     if (err < 0) {
508         alsa_logerr2 (err, typ, "Failed to set number of channels %d\n",
509                       req->nchannels);
510         goto err;
511     }
512 
513     if (apdo->buffer_length) {
514         int dir = 0;
515         unsigned int btime = apdo->buffer_length;
516 
517         err = snd_pcm_hw_params_set_buffer_time_near(
518             handle, hw_params, &btime, &dir);
519 
520         if (err < 0) {
521             alsa_logerr2(err, typ, "Failed to set buffer time to %" PRId32 "\n",
522                          apdo->buffer_length);
523             goto err;
524         }
525 
526         if (apdo->has_buffer_length && btime != apdo->buffer_length) {
527             dolog("Requested buffer time %" PRId32
528                   " was rejected, using %u\n", apdo->buffer_length, btime);
529         }
530     }
531 
532     if (apdo->period_length) {
533         int dir = 0;
534         unsigned int ptime = apdo->period_length;
535 
536         err = snd_pcm_hw_params_set_period_time_near(handle, hw_params, &ptime,
537                                                      &dir);
538 
539         if (err < 0) {
540             alsa_logerr2(err, typ, "Failed to set period time to %" PRId32 "\n",
541                          apdo->period_length);
542             goto err;
543         }
544 
545         if (apdo->has_period_length && ptime != apdo->period_length) {
546             dolog("Requested period time %" PRId32 " was rejected, using %d\n",
547                   apdo->period_length, ptime);
548         }
549     }
550 
551     err = snd_pcm_hw_params (handle, hw_params);
552     if (err < 0) {
553         alsa_logerr2 (err, typ, "Failed to apply audio parameters\n");
554         goto err;
555     }
556 
557     err = snd_pcm_hw_params_get_buffer_size (hw_params, &obt_buffer_size);
558     if (err < 0) {
559         alsa_logerr2 (err, typ, "Failed to get buffer size\n");
560         goto err;
561     }
562 
563     err = snd_pcm_hw_params_get_format (hw_params, &obtfmt);
564     if (err < 0) {
565         alsa_logerr2 (err, typ, "Failed to get format\n");
566         goto err;
567     }
568 
569     if (alsa_to_audfmt (obtfmt, &obt->fmt, &obt->endianness)) {
570         dolog ("Invalid format was returned %d\n", obtfmt);
571         goto err;
572     }
573 
574     err = snd_pcm_prepare (handle);
575     if (err < 0) {
576         alsa_logerr2 (err, typ, "Could not prepare handle %p\n", handle);
577         goto err;
578     }
579 
580     if (!in && aopts->has_threshold && aopts->threshold) {
581         struct audsettings as = { .freq = freq };
582         alsa_set_threshold(
583             handle,
584             audio_buffer_frames(qapi_AudiodevAlsaPerDirectionOptions_base(apdo),
585                                 &as, aopts->threshold));
586     }
587 
588     obt->nchannels = nchannels;
589     obt->freq = freq;
590     obt->samples = obt_buffer_size;
591 
592     *handlep = handle;
593 
594     if (obtfmt != req->fmt ||
595          obt->nchannels != req->nchannels ||
596          obt->freq != req->freq) {
597         dolog ("Audio parameters for %s\n", typ);
598         alsa_dump_info(req, obt, obtfmt, apdo);
599     }
600 
601 #ifdef DEBUG
602     alsa_dump_info(req, obt, obtfmt, pdo);
603 #endif
604     return 0;
605 
606  err:
607     alsa_anal_close1 (&handle);
608     return -1;
609 }
610 
611 static size_t alsa_write(HWVoiceOut *hw, void *buf, size_t len)
612 {
613     ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
614     size_t pos = 0;
615     size_t len_frames = len / hw->info.bytes_per_frame;
616 
617     while (len_frames) {
618         char *src = advance(buf, pos);
619         snd_pcm_sframes_t written;
620 
621         written = snd_pcm_writei(alsa->handle, src, len_frames);
622 
623         if (written <= 0) {
624             switch (written) {
625             case 0:
626                 trace_alsa_wrote_zero(len_frames);
627                 return pos;
628 
629             case -EPIPE:
630                 if (alsa_recover(alsa->handle)) {
631                     alsa_logerr(written, "Failed to write %zu frames\n",
632                                 len_frames);
633                     return pos;
634                 }
635                 trace_alsa_xrun_out();
636                 continue;
637 
638             case -ESTRPIPE:
639                 /*
640                  * stream is suspended and waiting for an application
641                  * recovery
642                  */
643                 if (alsa_resume(alsa->handle)) {
644                     alsa_logerr(written, "Failed to write %zu frames\n",
645                                 len_frames);
646                     return pos;
647                 }
648                 trace_alsa_resume_out();
649                 continue;
650 
651             case -EAGAIN:
652                 return pos;
653 
654             default:
655                 alsa_logerr(written, "Failed to write %zu frames from %p\n",
656                             len, src);
657                 return pos;
658             }
659         }
660 
661         pos += written * hw->info.bytes_per_frame;
662         if (written < len_frames) {
663             break;
664         }
665         len_frames -= written;
666     }
667 
668     return pos;
669 }
670 
671 static void alsa_fini_out (HWVoiceOut *hw)
672 {
673     ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
674 
675     ldebug ("alsa_fini\n");
676     alsa_anal_close (&alsa->handle, &alsa->pollhlp);
677 }
678 
679 static int alsa_init_out(HWVoiceOut *hw, struct audsettings *as,
680                          void *drv_opaque)
681 {
682     ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
683     struct alsa_params_req req;
684     struct alsa_params_obt obt;
685     snd_pcm_t *handle;
686     struct audsettings obt_as;
687     Audiodev *dev = drv_opaque;
688 
689     req.fmt = aud_to_alsafmt (as->fmt, as->endianness);
690     req.freq = as->freq;
691     req.nchannels = as->nchannels;
692 
693     if (alsa_open(0, &req, &obt, &handle, dev)) {
694         return -1;
695     }
696 
697     obt_as.freq = obt.freq;
698     obt_as.nchannels = obt.nchannels;
699     obt_as.fmt = obt.fmt;
700     obt_as.endianness = obt.endianness;
701 
702     audio_pcm_init_info (&hw->info, &obt_as);
703     hw->samples = obt.samples;
704 
705     alsa->pollhlp.s = hw->s;
706     alsa->handle = handle;
707     alsa->dev = dev;
708     return 0;
709 }
710 
711 #define VOICE_CTL_PAUSE 0
712 #define VOICE_CTL_PREPARE 1
713 #define VOICE_CTL_START 2
714 
715 static int alsa_voice_ctl (snd_pcm_t *handle, const char *typ, int ctl)
716 {
717     int err;
718 
719     if (ctl == VOICE_CTL_PAUSE) {
720         err = snd_pcm_drop (handle);
721         if (err < 0) {
722             alsa_logerr (err, "Could not stop %s\n", typ);
723             return -1;
724         }
725     }
726     else {
727         err = snd_pcm_prepare (handle);
728         if (err < 0) {
729             alsa_logerr (err, "Could not prepare handle for %s\n", typ);
730             return -1;
731         }
732         if (ctl == VOICE_CTL_START) {
733             err = snd_pcm_start(handle);
734             if (err < 0) {
735                 alsa_logerr (err, "Could not start handle for %s\n", typ);
736                 return -1;
737             }
738         }
739     }
740 
741     return 0;
742 }
743 
744 static void alsa_enable_out(HWVoiceOut *hw, bool enable)
745 {
746     ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
747     AudiodevAlsaPerDirectionOptions *apdo = alsa->dev->u.alsa.out;
748 
749     if (enable) {
750         bool poll_mode = apdo->try_poll;
751 
752         ldebug("enabling voice\n");
753         if (poll_mode && alsa_poll_out(hw)) {
754             poll_mode = 0;
755         }
756         hw->poll_mode = poll_mode;
757         alsa_voice_ctl(alsa->handle, "playback", VOICE_CTL_PREPARE);
758     } else {
759         ldebug("disabling voice\n");
760         if (hw->poll_mode) {
761             hw->poll_mode = 0;
762             alsa_fini_poll(&alsa->pollhlp);
763         }
764         alsa_voice_ctl(alsa->handle, "playback", VOICE_CTL_PAUSE);
765     }
766 }
767 
768 static int alsa_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
769 {
770     ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
771     struct alsa_params_req req;
772     struct alsa_params_obt obt;
773     snd_pcm_t *handle;
774     struct audsettings obt_as;
775     Audiodev *dev = drv_opaque;
776 
777     req.fmt = aud_to_alsafmt (as->fmt, as->endianness);
778     req.freq = as->freq;
779     req.nchannels = as->nchannels;
780 
781     if (alsa_open(1, &req, &obt, &handle, dev)) {
782         return -1;
783     }
784 
785     obt_as.freq = obt.freq;
786     obt_as.nchannels = obt.nchannels;
787     obt_as.fmt = obt.fmt;
788     obt_as.endianness = obt.endianness;
789 
790     audio_pcm_init_info (&hw->info, &obt_as);
791     hw->samples = obt.samples;
792 
793     alsa->pollhlp.s = hw->s;
794     alsa->handle = handle;
795     alsa->dev = dev;
796     return 0;
797 }
798 
799 static void alsa_fini_in (HWVoiceIn *hw)
800 {
801     ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
802 
803     alsa_anal_close (&alsa->handle, &alsa->pollhlp);
804 }
805 
806 static size_t alsa_read(HWVoiceIn *hw, void *buf, size_t len)
807 {
808     ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
809     size_t pos = 0;
810 
811     while (len) {
812         void *dst = advance(buf, pos);
813         snd_pcm_sframes_t nread;
814 
815         nread = snd_pcm_readi(
816             alsa->handle, dst, len / hw->info.bytes_per_frame);
817 
818         if (nread <= 0) {
819             switch (nread) {
820             case 0:
821                 trace_alsa_read_zero(len);
822                 return pos;
823 
824             case -EPIPE:
825                 if (alsa_recover(alsa->handle)) {
826                     alsa_logerr(nread, "Failed to read %zu frames\n", len);
827                     return pos;
828                 }
829                 trace_alsa_xrun_in();
830                 continue;
831 
832             case -EAGAIN:
833                 return pos;
834 
835             default:
836                 alsa_logerr(nread, "Failed to read %zu frames to %p\n",
837                             len, dst);
838                 return pos;
839             }
840         }
841 
842         pos += nread * hw->info.bytes_per_frame;
843         len -= nread * hw->info.bytes_per_frame;
844     }
845 
846     return pos;
847 }
848 
849 static void alsa_enable_in(HWVoiceIn *hw, bool enable)
850 {
851     ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
852     AudiodevAlsaPerDirectionOptions *apdo = alsa->dev->u.alsa.in;
853 
854     if (enable) {
855         bool poll_mode = apdo->try_poll;
856 
857         ldebug("enabling voice\n");
858         if (poll_mode && alsa_poll_in(hw)) {
859             poll_mode = 0;
860         }
861         hw->poll_mode = poll_mode;
862 
863         alsa_voice_ctl(alsa->handle, "capture", VOICE_CTL_START);
864     } else {
865         ldebug ("disabling voice\n");
866         if (hw->poll_mode) {
867             hw->poll_mode = 0;
868             alsa_fini_poll(&alsa->pollhlp);
869         }
870         alsa_voice_ctl(alsa->handle, "capture", VOICE_CTL_PAUSE);
871     }
872 }
873 
874 static void alsa_init_per_direction(AudiodevAlsaPerDirectionOptions *apdo)
875 {
876     if (!apdo->has_try_poll) {
877         apdo->try_poll = true;
878         apdo->has_try_poll = true;
879     }
880 }
881 
882 static void *alsa_audio_init(Audiodev *dev)
883 {
884     AudiodevAlsaOptions *aopts;
885     assert(dev->driver == AUDIODEV_DRIVER_ALSA);
886 
887     aopts = &dev->u.alsa;
888     alsa_init_per_direction(aopts->in);
889     alsa_init_per_direction(aopts->out);
890 
891     /*
892      * need to define them, as otherwise alsa produces no sound
893      * doesn't set has_* so alsa_open can identify it wasn't set by the user
894      */
895     if (!dev->u.alsa.out->has_period_length) {
896         /* 1024 frames assuming 44100Hz */
897         dev->u.alsa.out->period_length = 1024 * 1000000 / 44100;
898     }
899     if (!dev->u.alsa.out->has_buffer_length) {
900         /* 4096 frames assuming 44100Hz */
901         dev->u.alsa.out->buffer_length = 4096ll * 1000000 / 44100;
902     }
903 
904     /*
905      * OptsVisitor sets unspecified optional fields to zero, but do not depend
906      * on it...
907      */
908     if (!dev->u.alsa.in->has_period_length) {
909         dev->u.alsa.in->period_length = 0;
910     }
911     if (!dev->u.alsa.in->has_buffer_length) {
912         dev->u.alsa.in->buffer_length = 0;
913     }
914 
915     return dev;
916 }
917 
918 static void alsa_audio_fini (void *opaque)
919 {
920 }
921 
922 static struct audio_pcm_ops alsa_pcm_ops = {
923     .init_out = alsa_init_out,
924     .fini_out = alsa_fini_out,
925     .write    = alsa_write,
926     .run_buffer_out = audio_generic_run_buffer_out,
927     .enable_out = alsa_enable_out,
928 
929     .init_in  = alsa_init_in,
930     .fini_in  = alsa_fini_in,
931     .read     = alsa_read,
932     .enable_in = alsa_enable_in,
933 };
934 
935 static struct audio_driver alsa_audio_driver = {
936     .name           = "alsa",
937     .descr          = "ALSA http://www.alsa-project.org",
938     .init           = alsa_audio_init,
939     .fini           = alsa_audio_fini,
940     .pcm_ops        = &alsa_pcm_ops,
941     .can_be_default = 1,
942     .max_voices_out = INT_MAX,
943     .max_voices_in  = INT_MAX,
944     .voice_size_out = sizeof (ALSAVoiceOut),
945     .voice_size_in  = sizeof (ALSAVoiceIn)
946 };
947 
948 static void register_audio_alsa(void)
949 {
950     audio_driver_register(&alsa_audio_driver);
951 }
952 type_init(register_audio_alsa);
953