xref: /openbmc/linux/sound/drivers/opl3/opl3_synth.c (revision 29c37341)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Copyright (c) by Uros Bizjak <uros@kss-loka.si>
4  *
5  *  Routines for OPL2/OPL3/OPL4 control
6  */
7 
8 #include <linux/slab.h>
9 #include <linux/export.h>
10 #include <linux/nospec.h>
11 #include <sound/opl3.h>
12 #include <sound/asound_fm.h>
13 #include "opl3_voice.h"
14 
15 #if IS_ENABLED(CONFIG_SND_SEQUENCER)
16 #define OPL3_SUPPORT_SYNTH
17 #endif
18 
19 /*
20  *    There is 18 possible 2 OP voices
21  *      (9 in the left and 9 in the right).
22  *      The first OP is the modulator and 2nd is the carrier.
23  *
24  *      The first three voices in the both sides may be connected
25  *      with another voice to a 4 OP voice. For example voice 0
26  *      can be connected with voice 3. The operators of voice 3 are
27  *      used as operators 3 and 4 of the new 4 OP voice.
28  *      In this case the 2 OP voice number 0 is the 'first half' and
29  *      voice 3 is the second.
30  */
31 
32 
33 /*
34  *    Register offset table for OPL2/3 voices,
35  *    OPL2 / one OPL3 register array side only
36  */
37 
38 char snd_opl3_regmap[MAX_OPL2_VOICES][4] =
39 {
40 /*	  OP1   OP2   OP3   OP4		*/
41 /*	 ------------------------	*/
42 	{ 0x00, 0x03, 0x08, 0x0b },
43 	{ 0x01, 0x04, 0x09, 0x0c },
44 	{ 0x02, 0x05, 0x0a, 0x0d },
45 
46 	{ 0x08, 0x0b, 0x00, 0x00 },
47 	{ 0x09, 0x0c, 0x00, 0x00 },
48 	{ 0x0a, 0x0d, 0x00, 0x00 },
49 
50 	{ 0x10, 0x13, 0x00, 0x00 },	/* used by percussive voices */
51 	{ 0x11, 0x14, 0x00, 0x00 },	/* if the percussive mode */
52 	{ 0x12, 0x15, 0x00, 0x00 }	/* is selected (only left reg block) */
53 };
54 
55 EXPORT_SYMBOL(snd_opl3_regmap);
56 
57 /*
58  * prototypes
59  */
60 static int snd_opl3_play_note(struct snd_opl3 * opl3, struct snd_dm_fm_note * note);
61 static int snd_opl3_set_voice(struct snd_opl3 * opl3, struct snd_dm_fm_voice * voice);
62 static int snd_opl3_set_params(struct snd_opl3 * opl3, struct snd_dm_fm_params * params);
63 static int snd_opl3_set_mode(struct snd_opl3 * opl3, int mode);
64 static int snd_opl3_set_connection(struct snd_opl3 * opl3, int connection);
65 
66 /* ------------------------------ */
67 
68 /*
69  * open the device exclusively
70  */
71 int snd_opl3_open(struct snd_hwdep * hw, struct file *file)
72 {
73 	return 0;
74 }
75 
76 /*
77  * ioctl for hwdep device:
78  */
79 int snd_opl3_ioctl(struct snd_hwdep * hw, struct file *file,
80 		   unsigned int cmd, unsigned long arg)
81 {
82 	struct snd_opl3 *opl3 = hw->private_data;
83 	void __user *argp = (void __user *)arg;
84 
85 	if (snd_BUG_ON(!opl3))
86 		return -EINVAL;
87 
88 	switch (cmd) {
89 		/* get information */
90 	case SNDRV_DM_FM_IOCTL_INFO:
91 		{
92 			struct snd_dm_fm_info info;
93 
94 			memset(&info, 0, sizeof(info));
95 
96 			info.fm_mode = opl3->fm_mode;
97 			info.rhythm = opl3->rhythm;
98 			if (copy_to_user(argp, &info, sizeof(struct snd_dm_fm_info)))
99 				return -EFAULT;
100 			return 0;
101 		}
102 
103 	case SNDRV_DM_FM_IOCTL_RESET:
104 #ifdef CONFIG_SND_OSSEMUL
105 	case SNDRV_DM_FM_OSS_IOCTL_RESET:
106 #endif
107 		snd_opl3_reset(opl3);
108 		return 0;
109 
110 	case SNDRV_DM_FM_IOCTL_PLAY_NOTE:
111 #ifdef CONFIG_SND_OSSEMUL
112 	case SNDRV_DM_FM_OSS_IOCTL_PLAY_NOTE:
113 #endif
114 		{
115 			struct snd_dm_fm_note note;
116 			if (copy_from_user(&note, argp, sizeof(struct snd_dm_fm_note)))
117 				return -EFAULT;
118 			return snd_opl3_play_note(opl3, &note);
119 		}
120 
121 	case SNDRV_DM_FM_IOCTL_SET_VOICE:
122 #ifdef CONFIG_SND_OSSEMUL
123 	case SNDRV_DM_FM_OSS_IOCTL_SET_VOICE:
124 #endif
125 		{
126 			struct snd_dm_fm_voice voice;
127 			if (copy_from_user(&voice, argp, sizeof(struct snd_dm_fm_voice)))
128 				return -EFAULT;
129 			return snd_opl3_set_voice(opl3, &voice);
130 		}
131 
132 	case SNDRV_DM_FM_IOCTL_SET_PARAMS:
133 #ifdef CONFIG_SND_OSSEMUL
134 	case SNDRV_DM_FM_OSS_IOCTL_SET_PARAMS:
135 #endif
136 		{
137 			struct snd_dm_fm_params params;
138 			if (copy_from_user(&params, argp, sizeof(struct snd_dm_fm_params)))
139 				return -EFAULT;
140 			return snd_opl3_set_params(opl3, &params);
141 		}
142 
143 	case SNDRV_DM_FM_IOCTL_SET_MODE:
144 #ifdef CONFIG_SND_OSSEMUL
145 	case SNDRV_DM_FM_OSS_IOCTL_SET_MODE:
146 #endif
147 		return snd_opl3_set_mode(opl3, (int) arg);
148 
149 	case SNDRV_DM_FM_IOCTL_SET_CONNECTION:
150 #ifdef CONFIG_SND_OSSEMUL
151 	case SNDRV_DM_FM_OSS_IOCTL_SET_OPL:
152 #endif
153 		return snd_opl3_set_connection(opl3, (int) arg);
154 
155 #ifdef OPL3_SUPPORT_SYNTH
156 	case SNDRV_DM_FM_IOCTL_CLEAR_PATCHES:
157 		snd_opl3_clear_patches(opl3);
158 		return 0;
159 #endif
160 
161 #ifdef CONFIG_SND_DEBUG
162 	default:
163 		snd_printk(KERN_WARNING "unknown IOCTL: 0x%x\n", cmd);
164 #endif
165 	}
166 	return -ENOTTY;
167 }
168 
169 /*
170  * close the device
171  */
172 int snd_opl3_release(struct snd_hwdep * hw, struct file *file)
173 {
174 	struct snd_opl3 *opl3 = hw->private_data;
175 
176 	snd_opl3_reset(opl3);
177 	return 0;
178 }
179 
180 #ifdef OPL3_SUPPORT_SYNTH
181 /*
182  * write the device - load patches
183  */
184 long snd_opl3_write(struct snd_hwdep *hw, const char __user *buf, long count,
185 		    loff_t *offset)
186 {
187 	struct snd_opl3 *opl3 = hw->private_data;
188 	long result = 0;
189 	int err = 0;
190 	struct sbi_patch inst;
191 
192 	while (count >= sizeof(inst)) {
193 		unsigned char type;
194 		if (copy_from_user(&inst, buf, sizeof(inst)))
195 			return -EFAULT;
196 		if (!memcmp(inst.key, FM_KEY_SBI, 4) ||
197 		    !memcmp(inst.key, FM_KEY_2OP, 4))
198 			type = FM_PATCH_OPL2;
199 		else if (!memcmp(inst.key, FM_KEY_4OP, 4))
200 			type = FM_PATCH_OPL3;
201 		else /* invalid type */
202 			break;
203 		err = snd_opl3_load_patch(opl3, inst.prog, inst.bank, type,
204 					  inst.name, inst.extension,
205 					  inst.data);
206 		if (err < 0)
207 			break;
208 		result += sizeof(inst);
209 		count -= sizeof(inst);
210 	}
211 	return result > 0 ? result : err;
212 }
213 
214 
215 /*
216  * Patch management
217  */
218 
219 /* offsets for SBI params */
220 #define AM_VIB		0
221 #define KSL_LEVEL	2
222 #define ATTACK_DECAY	4
223 #define SUSTAIN_RELEASE	6
224 #define WAVE_SELECT	8
225 
226 /* offset for SBI instrument */
227 #define CONNECTION	10
228 #define OFFSET_4OP	11
229 
230 /*
231  * load a patch, obviously.
232  *
233  * loaded on the given program and bank numbers with the given type
234  * (FM_PATCH_OPLx).
235  * data is the pointer of SBI record _without_ header (key and name).
236  * name is the name string of the patch.
237  * ext is the extension data of 7 bytes long (stored in name of SBI
238  * data up to offset 25), or NULL to skip.
239  * return 0 if successful or a negative error code.
240  */
241 int snd_opl3_load_patch(struct snd_opl3 *opl3,
242 			int prog, int bank, int type,
243 			const char *name,
244 			const unsigned char *ext,
245 			const unsigned char *data)
246 {
247 	struct fm_patch *patch;
248 	int i;
249 
250 	patch = snd_opl3_find_patch(opl3, prog, bank, 1);
251 	if (!patch)
252 		return -ENOMEM;
253 
254 	patch->type = type;
255 
256 	for (i = 0; i < 2; i++) {
257 		patch->inst.op[i].am_vib = data[AM_VIB + i];
258 		patch->inst.op[i].ksl_level = data[KSL_LEVEL + i];
259 		patch->inst.op[i].attack_decay = data[ATTACK_DECAY + i];
260 		patch->inst.op[i].sustain_release = data[SUSTAIN_RELEASE + i];
261 		patch->inst.op[i].wave_select = data[WAVE_SELECT + i];
262 	}
263 	patch->inst.feedback_connection[0] = data[CONNECTION];
264 
265 	if (type == FM_PATCH_OPL3) {
266 		for (i = 0; i < 2; i++) {
267 			patch->inst.op[i+2].am_vib =
268 				data[OFFSET_4OP + AM_VIB + i];
269 			patch->inst.op[i+2].ksl_level =
270 				data[OFFSET_4OP + KSL_LEVEL + i];
271 			patch->inst.op[i+2].attack_decay =
272 				data[OFFSET_4OP + ATTACK_DECAY + i];
273 			patch->inst.op[i+2].sustain_release =
274 				data[OFFSET_4OP + SUSTAIN_RELEASE + i];
275 			patch->inst.op[i+2].wave_select =
276 				data[OFFSET_4OP + WAVE_SELECT + i];
277 		}
278 		patch->inst.feedback_connection[1] =
279 			data[OFFSET_4OP + CONNECTION];
280 	}
281 
282 	if (ext) {
283 		patch->inst.echo_delay = ext[0];
284 		patch->inst.echo_atten = ext[1];
285 		patch->inst.chorus_spread = ext[2];
286 		patch->inst.trnsps = ext[3];
287 		patch->inst.fix_dur = ext[4];
288 		patch->inst.modes = ext[5];
289 		patch->inst.fix_key = ext[6];
290 	}
291 
292 	if (name)
293 		strlcpy(patch->name, name, sizeof(patch->name));
294 
295 	return 0;
296 }
297 EXPORT_SYMBOL(snd_opl3_load_patch);
298 
299 /*
300  * find a patch with the given program and bank numbers, returns its pointer
301  * if no matching patch is found and create_patch is set, it creates a
302  * new patch object.
303  */
304 struct fm_patch *snd_opl3_find_patch(struct snd_opl3 *opl3, int prog, int bank,
305 				     int create_patch)
306 {
307 	/* pretty dumb hash key */
308 	unsigned int key = (prog + bank) % OPL3_PATCH_HASH_SIZE;
309 	struct fm_patch *patch;
310 
311 	for (patch = opl3->patch_table[key]; patch; patch = patch->next) {
312 		if (patch->prog == prog && patch->bank == bank)
313 			return patch;
314 	}
315 	if (!create_patch)
316 		return NULL;
317 
318 	patch = kzalloc(sizeof(*patch), GFP_KERNEL);
319 	if (!patch)
320 		return NULL;
321 	patch->prog = prog;
322 	patch->bank = bank;
323 	patch->next = opl3->patch_table[key];
324 	opl3->patch_table[key] = patch;
325 	return patch;
326 }
327 EXPORT_SYMBOL(snd_opl3_find_patch);
328 
329 /*
330  * Clear all patches of the given OPL3 instance
331  */
332 void snd_opl3_clear_patches(struct snd_opl3 *opl3)
333 {
334 	int i;
335 	for (i = 0; i <  OPL3_PATCH_HASH_SIZE; i++) {
336 		struct fm_patch *patch, *next;
337 		for (patch = opl3->patch_table[i]; patch; patch = next) {
338 			next = patch->next;
339 			kfree(patch);
340 		}
341 	}
342 	memset(opl3->patch_table, 0, sizeof(opl3->patch_table));
343 }
344 #endif /* OPL3_SUPPORT_SYNTH */
345 
346 /* ------------------------------ */
347 
348 void snd_opl3_reset(struct snd_opl3 * opl3)
349 {
350 	unsigned short opl3_reg;
351 
352 	unsigned short reg_side;
353 	unsigned char voice_offset;
354 
355 	int max_voices, i;
356 
357 	max_voices = (opl3->hardware < OPL3_HW_OPL3) ?
358 		MAX_OPL2_VOICES : MAX_OPL3_VOICES;
359 
360 	for (i = 0; i < max_voices; i++) {
361 		/* Get register array side and offset of voice */
362 		if (i < MAX_OPL2_VOICES) {
363 			/* Left register block for voices 0 .. 8 */
364 			reg_side = OPL3_LEFT;
365 			voice_offset = i;
366 		} else {
367 			/* Right register block for voices 9 .. 17 */
368 			reg_side = OPL3_RIGHT;
369 			voice_offset = i - MAX_OPL2_VOICES;
370 		}
371 		opl3_reg = reg_side | (OPL3_REG_KSL_LEVEL + snd_opl3_regmap[voice_offset][0]);
372 		opl3->command(opl3, opl3_reg, OPL3_TOTAL_LEVEL_MASK); /* Operator 1 volume */
373 		opl3_reg = reg_side | (OPL3_REG_KSL_LEVEL + snd_opl3_regmap[voice_offset][1]);
374 		opl3->command(opl3, opl3_reg, OPL3_TOTAL_LEVEL_MASK); /* Operator 2 volume */
375 
376 		opl3_reg = reg_side | (OPL3_REG_KEYON_BLOCK + voice_offset);
377 		opl3->command(opl3, opl3_reg, 0x00);	/* Note off */
378 	}
379 
380 	opl3->max_voices = MAX_OPL2_VOICES;
381 	opl3->fm_mode = SNDRV_DM_FM_MODE_OPL2;
382 
383 	opl3->command(opl3, OPL3_LEFT | OPL3_REG_TEST, OPL3_ENABLE_WAVE_SELECT);
384 	opl3->command(opl3, OPL3_LEFT | OPL3_REG_PERCUSSION, 0x00);	/* Melodic mode */
385 	opl3->rhythm = 0;
386 }
387 
388 EXPORT_SYMBOL(snd_opl3_reset);
389 
390 static int snd_opl3_play_note(struct snd_opl3 * opl3, struct snd_dm_fm_note * note)
391 {
392 	unsigned short reg_side;
393 	unsigned char voice_offset;
394 
395 	unsigned short opl3_reg;
396 	unsigned char reg_val;
397 
398 	/* Voices 0 -  8 in OPL2 mode */
399 	/* Voices 0 - 17 in OPL3 mode */
400 	if (note->voice >= ((opl3->fm_mode == SNDRV_DM_FM_MODE_OPL3) ?
401 			    MAX_OPL3_VOICES : MAX_OPL2_VOICES))
402 		return -EINVAL;
403 
404 	/* Get register array side and offset of voice */
405 	if (note->voice < MAX_OPL2_VOICES) {
406 		/* Left register block for voices 0 .. 8 */
407 		reg_side = OPL3_LEFT;
408 		voice_offset = note->voice;
409 	} else {
410 		/* Right register block for voices 9 .. 17 */
411 		reg_side = OPL3_RIGHT;
412 		voice_offset = note->voice - MAX_OPL2_VOICES;
413 	}
414 
415 	/* Set lower 8 bits of note frequency */
416 	reg_val = (unsigned char) note->fnum;
417 	opl3_reg = reg_side | (OPL3_REG_FNUM_LOW + voice_offset);
418 	opl3->command(opl3, opl3_reg, reg_val);
419 
420 	reg_val = 0x00;
421 	/* Set output sound flag */
422 	if (note->key_on)
423 		reg_val |= OPL3_KEYON_BIT;
424 	/* Set octave */
425 	reg_val |= (note->octave << 2) & OPL3_BLOCKNUM_MASK;
426 	/* Set higher 2 bits of note frequency */
427 	reg_val |= (unsigned char) (note->fnum >> 8) & OPL3_FNUM_HIGH_MASK;
428 
429 	/* Set OPL3 KEYON_BLOCK register of requested voice */
430 	opl3_reg = reg_side | (OPL3_REG_KEYON_BLOCK + voice_offset);
431 	opl3->command(opl3, opl3_reg, reg_val);
432 
433 	return 0;
434 }
435 
436 
437 static int snd_opl3_set_voice(struct snd_opl3 * opl3, struct snd_dm_fm_voice * voice)
438 {
439 	unsigned short reg_side;
440 	unsigned char op_offset;
441 	unsigned char voice_offset, voice_op;
442 
443 	unsigned short opl3_reg;
444 	unsigned char reg_val;
445 
446 	/* Only operators 1 and 2 */
447 	if (voice->op > 1)
448 		return -EINVAL;
449 	/* Voices 0 -  8 in OPL2 mode */
450 	/* Voices 0 - 17 in OPL3 mode */
451 	if (voice->voice >= ((opl3->fm_mode == SNDRV_DM_FM_MODE_OPL3) ?
452 			     MAX_OPL3_VOICES : MAX_OPL2_VOICES))
453 		return -EINVAL;
454 
455 	/* Get register array side and offset of voice */
456 	if (voice->voice < MAX_OPL2_VOICES) {
457 		/* Left register block for voices 0 .. 8 */
458 		reg_side = OPL3_LEFT;
459 		voice_offset = voice->voice;
460 	} else {
461 		/* Right register block for voices 9 .. 17 */
462 		reg_side = OPL3_RIGHT;
463 		voice_offset = voice->voice - MAX_OPL2_VOICES;
464 	}
465 	/* Get register offset of operator */
466 	voice_offset = array_index_nospec(voice_offset, MAX_OPL2_VOICES);
467 	voice_op = array_index_nospec(voice->op, 4);
468 	op_offset = snd_opl3_regmap[voice_offset][voice_op];
469 
470 	reg_val = 0x00;
471 	/* Set amplitude modulation (tremolo) effect */
472 	if (voice->am)
473 		reg_val |= OPL3_TREMOLO_ON;
474 	/* Set vibrato effect */
475 	if (voice->vibrato)
476 		reg_val |= OPL3_VIBRATO_ON;
477 	/* Set sustaining sound phase */
478 	if (voice->do_sustain)
479 		reg_val |= OPL3_SUSTAIN_ON;
480 	/* Set keyboard scaling bit */
481 	if (voice->kbd_scale)
482 		reg_val |= OPL3_KSR;
483 	/* Set harmonic or frequency multiplier */
484 	reg_val |= voice->harmonic & OPL3_MULTIPLE_MASK;
485 
486 	/* Set OPL3 AM_VIB register of requested voice/operator */
487 	opl3_reg = reg_side | (OPL3_REG_AM_VIB + op_offset);
488 	opl3->command(opl3, opl3_reg, reg_val);
489 
490 	/* Set decreasing volume of higher notes */
491 	reg_val = (voice->scale_level << 6) & OPL3_KSL_MASK;
492 	/* Set output volume */
493 	reg_val |= ~voice->volume & OPL3_TOTAL_LEVEL_MASK;
494 
495 	/* Set OPL3 KSL_LEVEL register of requested voice/operator */
496 	opl3_reg = reg_side | (OPL3_REG_KSL_LEVEL + op_offset);
497 	opl3->command(opl3, opl3_reg, reg_val);
498 
499 	/* Set attack phase level */
500 	reg_val = (voice->attack << 4) & OPL3_ATTACK_MASK;
501 	/* Set decay phase level */
502 	reg_val |= voice->decay & OPL3_DECAY_MASK;
503 
504 	/* Set OPL3 ATTACK_DECAY register of requested voice/operator */
505 	opl3_reg = reg_side | (OPL3_REG_ATTACK_DECAY + op_offset);
506 	opl3->command(opl3, opl3_reg, reg_val);
507 
508 	/* Set sustain phase level */
509 	reg_val = (voice->sustain << 4) & OPL3_SUSTAIN_MASK;
510 	/* Set release phase level */
511 	reg_val |= voice->release & OPL3_RELEASE_MASK;
512 
513 	/* Set OPL3 SUSTAIN_RELEASE register of requested voice/operator */
514 	opl3_reg = reg_side | (OPL3_REG_SUSTAIN_RELEASE + op_offset);
515 	opl3->command(opl3, opl3_reg, reg_val);
516 
517 	/* Set inter-operator feedback */
518 	reg_val = (voice->feedback << 1) & OPL3_FEEDBACK_MASK;
519 	/* Set inter-operator connection */
520 	if (voice->connection)
521 		reg_val |= OPL3_CONNECTION_BIT;
522 	/* OPL-3 only */
523 	if (opl3->fm_mode == SNDRV_DM_FM_MODE_OPL3) {
524 		if (voice->left)
525 			reg_val |= OPL3_VOICE_TO_LEFT;
526 		if (voice->right)
527 			reg_val |= OPL3_VOICE_TO_RIGHT;
528 	}
529 	/* Feedback/connection bits are applicable to voice */
530 	opl3_reg = reg_side | (OPL3_REG_FEEDBACK_CONNECTION + voice_offset);
531 	opl3->command(opl3, opl3_reg, reg_val);
532 
533 	/* Select waveform */
534 	reg_val = voice->waveform & OPL3_WAVE_SELECT_MASK;
535 	opl3_reg = reg_side | (OPL3_REG_WAVE_SELECT + op_offset);
536 	opl3->command(opl3, opl3_reg, reg_val);
537 
538 	return 0;
539 }
540 
541 static int snd_opl3_set_params(struct snd_opl3 * opl3, struct snd_dm_fm_params * params)
542 {
543 	unsigned char reg_val;
544 
545 	reg_val = 0x00;
546 	/* Set keyboard split method */
547 	if (params->kbd_split)
548 		reg_val |= OPL3_KEYBOARD_SPLIT;
549 	opl3->command(opl3, OPL3_LEFT | OPL3_REG_KBD_SPLIT, reg_val);
550 
551 	reg_val = 0x00;
552 	/* Set amplitude modulation (tremolo) depth */
553 	if (params->am_depth)
554 		reg_val |= OPL3_TREMOLO_DEPTH;
555 	/* Set vibrato depth */
556 	if (params->vib_depth)
557 		reg_val |= OPL3_VIBRATO_DEPTH;
558 	/* Set percussion mode */
559 	if (params->rhythm) {
560 		reg_val |= OPL3_PERCUSSION_ENABLE;
561 		opl3->rhythm = 1;
562 	} else {
563 		opl3->rhythm = 0;
564 	}
565 	/* Play percussion instruments */
566 	if (params->bass)
567 		reg_val |= OPL3_BASSDRUM_ON;
568 	if (params->snare)
569 		reg_val |= OPL3_SNAREDRUM_ON;
570 	if (params->tomtom)
571 		reg_val |= OPL3_TOMTOM_ON;
572 	if (params->cymbal)
573 		reg_val |= OPL3_CYMBAL_ON;
574 	if (params->hihat)
575 		reg_val |= OPL3_HIHAT_ON;
576 
577 	opl3->command(opl3, OPL3_LEFT | OPL3_REG_PERCUSSION, reg_val);
578 	return 0;
579 }
580 
581 static int snd_opl3_set_mode(struct snd_opl3 * opl3, int mode)
582 {
583 	if ((mode == SNDRV_DM_FM_MODE_OPL3) && (opl3->hardware < OPL3_HW_OPL3))
584 		return -EINVAL;
585 
586 	opl3->fm_mode = mode;
587 	if (opl3->hardware >= OPL3_HW_OPL3)
588 		opl3->command(opl3, OPL3_RIGHT | OPL3_REG_CONNECTION_SELECT, 0x00);	/* Clear 4-op connections */
589 
590 	return 0;
591 }
592 
593 static int snd_opl3_set_connection(struct snd_opl3 * opl3, int connection)
594 {
595 	unsigned char reg_val;
596 
597 	/* OPL-3 only */
598 	if (opl3->fm_mode != SNDRV_DM_FM_MODE_OPL3)
599 		return -EINVAL;
600 
601 	reg_val = connection & (OPL3_RIGHT_4OP_0 | OPL3_RIGHT_4OP_1 | OPL3_RIGHT_4OP_2 |
602 				OPL3_LEFT_4OP_0 | OPL3_LEFT_4OP_1 | OPL3_LEFT_4OP_2);
603 	/* Set 4-op connections */
604 	opl3->command(opl3, OPL3_RIGHT | OPL3_REG_CONNECTION_SELECT, reg_val);
605 
606 	return 0;
607 }
608 
609