Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 622 insertions, 0 deletions

diff --git a/sound/drivers/opl3/opl3_synth.c b/sound/drivers/opl3/opl3_synth.c
new file mode 100644
index 000000000..1a87f8ea0
--- /dev/null
+++ b/sound/drivers/opl3/opl3_synth.c
@@ -0,0 +1,622 @@
+/*
+ *  Copyright (c) by Uros Bizjak <uros@kss-loka.si>
+ *                   
+ *  Routines for OPL2/OPL3/OPL4 control
+ *
+ *   This program is free software; you can redistribute it and/or modify 
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ */
+
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/nospec.h>
+#include <sound/opl3.h>
+#include <sound/asound_fm.h>
+#include "opl3_voice.h"
+
+#if IS_ENABLED(CONFIG_SND_SEQUENCER)
+#define OPL3_SUPPORT_SYNTH
+#endif
+
+/*
+ *    There is 18 possible 2 OP voices
+ *      (9 in the left and 9 in the right).
+ *      The first OP is the modulator and 2nd is the carrier.
+ *
+ *      The first three voices in the both sides may be connected
+ *      with another voice to a 4 OP voice. For example voice 0
+ *      can be connected with voice 3. The operators of voice 3 are
+ *      used as operators 3 and 4 of the new 4 OP voice.
+ *      In this case the 2 OP voice number 0 is the 'first half' and
+ *      voice 3 is the second.
+ */
+
+
+/*
+ *    Register offset table for OPL2/3 voices,
+ *    OPL2 / one OPL3 register array side only
+ */
+
+char snd_opl3_regmap[MAX_OPL2_VOICES][4] =
+{
+/*	  OP1   OP2   OP3   OP4		*/
+/*	 ------------------------	*/
+	{ 0x00, 0x03, 0x08, 0x0b },
+	{ 0x01, 0x04, 0x09, 0x0c },
+	{ 0x02, 0x05, 0x0a, 0x0d },
+
+	{ 0x08, 0x0b, 0x00, 0x00 },
+	{ 0x09, 0x0c, 0x00, 0x00 },
+	{ 0x0a, 0x0d, 0x00, 0x00 },
+
+	{ 0x10, 0x13, 0x00, 0x00 },	/* used by percussive voices */
+	{ 0x11, 0x14, 0x00, 0x00 },	/* if the percussive mode */
+	{ 0x12, 0x15, 0x00, 0x00 }	/* is selected (only left reg block) */
+};
+
+EXPORT_SYMBOL(snd_opl3_regmap);
+
+/*
+ * prototypes
+ */
+static int snd_opl3_play_note(struct snd_opl3 * opl3, struct snd_dm_fm_note * note);
+static int snd_opl3_set_voice(struct snd_opl3 * opl3, struct snd_dm_fm_voice * voice);
+static int snd_opl3_set_params(struct snd_opl3 * opl3, struct snd_dm_fm_params * params);
+static int snd_opl3_set_mode(struct snd_opl3 * opl3, int mode);
+static int snd_opl3_set_connection(struct snd_opl3 * opl3, int connection);
+
+/* ------------------------------ */
+
+/*
+ * open the device exclusively
+ */
+int snd_opl3_open(struct snd_hwdep * hw, struct file *file)
+{
+	return 0;
+}
+
+/*
+ * ioctl for hwdep device:
+ */
+int snd_opl3_ioctl(struct snd_hwdep * hw, struct file *file,
+		   unsigned int cmd, unsigned long arg)
+{
+	struct snd_opl3 *opl3 = hw->private_data;
+	void __user *argp = (void __user *)arg;
+
+	if (snd_BUG_ON(!opl3))
+		return -EINVAL;
+
+	switch (cmd) {
+		/* get information */
+	case SNDRV_DM_FM_IOCTL_INFO:
+		{
+			struct snd_dm_fm_info info;
+
+			memset(&info, 0, sizeof(info));
+
+			info.fm_mode = opl3->fm_mode;
+			info.rhythm = opl3->rhythm;
+			if (copy_to_user(argp, &info, sizeof(struct snd_dm_fm_info)))
+				return -EFAULT;
+			return 0;
+		}
+
+	case SNDRV_DM_FM_IOCTL_RESET:
+#ifdef CONFIG_SND_OSSEMUL
+	case SNDRV_DM_FM_OSS_IOCTL_RESET:
+#endif
+		snd_opl3_reset(opl3);
+		return 0;
+
+	case SNDRV_DM_FM_IOCTL_PLAY_NOTE:
+#ifdef CONFIG_SND_OSSEMUL
+	case SNDRV_DM_FM_OSS_IOCTL_PLAY_NOTE:
+#endif
+		{
+			struct snd_dm_fm_note note;
+			if (copy_from_user(&note, argp, sizeof(struct snd_dm_fm_note)))
+				return -EFAULT;
+			return snd_opl3_play_note(opl3, &note);
+		}
+
+	case SNDRV_DM_FM_IOCTL_SET_VOICE:
+#ifdef CONFIG_SND_OSSEMUL
+	case SNDRV_DM_FM_OSS_IOCTL_SET_VOICE:
+#endif
+		{
+			struct snd_dm_fm_voice voice;
+			if (copy_from_user(&voice, argp, sizeof(struct snd_dm_fm_voice)))
+				return -EFAULT;
+			return snd_opl3_set_voice(opl3, &voice);
+		}
+
+	case SNDRV_DM_FM_IOCTL_SET_PARAMS:
+#ifdef CONFIG_SND_OSSEMUL
+	case SNDRV_DM_FM_OSS_IOCTL_SET_PARAMS:
+#endif
+		{
+			struct snd_dm_fm_params params;
+			if (copy_from_user(&params, argp, sizeof(struct snd_dm_fm_params)))
+				return -EFAULT;
+			return snd_opl3_set_params(opl3, &params);
+		}
+
+	case SNDRV_DM_FM_IOCTL_SET_MODE:
+#ifdef CONFIG_SND_OSSEMUL
+	case SNDRV_DM_FM_OSS_IOCTL_SET_MODE:
+#endif
+		return snd_opl3_set_mode(opl3, (int) arg);
+
+	case SNDRV_DM_FM_IOCTL_SET_CONNECTION:
+#ifdef CONFIG_SND_OSSEMUL
+	case SNDRV_DM_FM_OSS_IOCTL_SET_OPL:
+#endif
+		return snd_opl3_set_connection(opl3, (int) arg);
+
+#ifdef OPL3_SUPPORT_SYNTH
+	case SNDRV_DM_FM_IOCTL_CLEAR_PATCHES:
+		snd_opl3_clear_patches(opl3);
+		return 0;
+#endif
+
+#ifdef CONFIG_SND_DEBUG
+	default:
+		snd_printk(KERN_WARNING "unknown IOCTL: 0x%x\n", cmd);
+#endif
+	}
+	return -ENOTTY;
+}
+
+/*
+ * close the device
+ */
+int snd_opl3_release(struct snd_hwdep * hw, struct file *file)
+{
+	struct snd_opl3 *opl3 = hw->private_data;
+
+	snd_opl3_reset(opl3);
+	return 0;
+}
+
+#ifdef OPL3_SUPPORT_SYNTH
+/*
+ * write the device - load patches
+ */
+long snd_opl3_write(struct snd_hwdep *hw, const char __user *buf, long count,
+		    loff_t *offset)
+{
+	struct snd_opl3 *opl3 = hw->private_data;
+	long result = 0;
+	int err = 0;
+	struct sbi_patch inst;
+
+	while (count >= sizeof(inst)) {
+		unsigned char type;
+		if (copy_from_user(&inst, buf, sizeof(inst)))
+			return -EFAULT;
+		if (!memcmp(inst.key, FM_KEY_SBI, 4) ||
+		    !memcmp(inst.key, FM_KEY_2OP, 4))
+			type = FM_PATCH_OPL2;
+		else if (!memcmp(inst.key, FM_KEY_4OP, 4))
+			type = FM_PATCH_OPL3;
+		else /* invalid type */
+			break;
+		err = snd_opl3_load_patch(opl3, inst.prog, inst.bank, type,
+					  inst.name, inst.extension,
+					  inst.data);
+		if (err < 0)
+			break;
+		result += sizeof(inst);
+		count -= sizeof(inst);
+	}
+	return result > 0 ? result : err;
+}
+
+
+/*
+ * Patch management
+ */
+
+/* offsets for SBI params */
+#define AM_VIB		0
+#define KSL_LEVEL	2
+#define ATTACK_DECAY	4
+#define SUSTAIN_RELEASE	6
+#define WAVE_SELECT	8
+
+/* offset for SBI instrument */
+#define CONNECTION	10
+#define OFFSET_4OP	11
+
+/*
+ * load a patch, obviously.
+ *
+ * loaded on the given program and bank numbers with the given type
+ * (FM_PATCH_OPLx).
+ * data is the pointer of SBI record _without_ header (key and name).
+ * name is the name string of the patch.
+ * ext is the extension data of 7 bytes long (stored in name of SBI
+ * data up to offset 25), or NULL to skip.
+ * return 0 if successful or a negative error code.
+ */
+int snd_opl3_load_patch(struct snd_opl3 *opl3,
+			int prog, int bank, int type,
+			const char *name,
+			const unsigned char *ext,
+			const unsigned char *data)
+{
+	struct fm_patch *patch;
+	int i;
+
+	patch = snd_opl3_find_patch(opl3, prog, bank, 1);
+	if (!patch)
+		return -ENOMEM;
+
+	patch->type = type;
+
+	for (i = 0; i < 2; i++) {
+		patch->inst.op[i].am_vib = data[AM_VIB + i];
+		patch->inst.op[i].ksl_level = data[KSL_LEVEL + i];
+		patch->inst.op[i].attack_decay = data[ATTACK_DECAY + i];
+		patch->inst.op[i].sustain_release = data[SUSTAIN_RELEASE + i];
+		patch->inst.op[i].wave_select = data[WAVE_SELECT + i];
+	}
+	patch->inst.feedback_connection[0] = data[CONNECTION];
+
+	if (type == FM_PATCH_OPL3) {
+		for (i = 0; i < 2; i++) {
+			patch->inst.op[i+2].am_vib =
+				data[OFFSET_4OP + AM_VIB + i];
+			patch->inst.op[i+2].ksl_level =
+				data[OFFSET_4OP + KSL_LEVEL + i];
+			patch->inst.op[i+2].attack_decay =
+				data[OFFSET_4OP + ATTACK_DECAY + i];
+			patch->inst.op[i+2].sustain_release =
+				data[OFFSET_4OP + SUSTAIN_RELEASE + i];
+			patch->inst.op[i+2].wave_select =
+				data[OFFSET_4OP + WAVE_SELECT + i];
+		}
+		patch->inst.feedback_connection[1] =
+			data[OFFSET_4OP + CONNECTION];
+	}
+
+	if (ext) {
+		patch->inst.echo_delay = ext[0];
+		patch->inst.echo_atten = ext[1];
+		patch->inst.chorus_spread = ext[2];
+		patch->inst.trnsps = ext[3];
+		patch->inst.fix_dur = ext[4];
+		patch->inst.modes = ext[5];
+		patch->inst.fix_key = ext[6];
+	}
+
+	if (name)
+		strlcpy(patch->name, name, sizeof(patch->name));
+
+	return 0;
+}
+EXPORT_SYMBOL(snd_opl3_load_patch);
+
+/*
+ * find a patch with the given program and bank numbers, returns its pointer
+ * if no matching patch is found and create_patch is set, it creates a
+ * new patch object.
+ */
+struct fm_patch *snd_opl3_find_patch(struct snd_opl3 *opl3, int prog, int bank,
+				     int create_patch)
+{
+	/* pretty dumb hash key */
+	unsigned int key = (prog + bank) % OPL3_PATCH_HASH_SIZE;
+	struct fm_patch *patch;
+
+	for (patch = opl3->patch_table[key]; patch; patch = patch->next) {
+		if (patch->prog == prog && patch->bank == bank)
+			return patch;
+	}
+	if (!create_patch)
+		return NULL;
+
+	patch = kzalloc(sizeof(*patch), GFP_KERNEL);
+	if (!patch)
+		return NULL;
+	patch->prog = prog;
+	patch->bank = bank;
+	patch->next = opl3->patch_table[key];
+	opl3->patch_table[key] = patch;
+	return patch;
+}
+EXPORT_SYMBOL(snd_opl3_find_patch);
+
+/*
+ * Clear all patches of the given OPL3 instance
+ */
+void snd_opl3_clear_patches(struct snd_opl3 *opl3)
+{
+	int i;
+	for (i = 0; i <  OPL3_PATCH_HASH_SIZE; i++) {
+		struct fm_patch *patch, *next;
+		for (patch = opl3->patch_table[i]; patch; patch = next) {
+			next = patch->next;
+			kfree(patch);
+		}
+	}
+	memset(opl3->patch_table, 0, sizeof(opl3->patch_table));
+}
+#endif /* OPL3_SUPPORT_SYNTH */
+
+/* ------------------------------ */
+
+void snd_opl3_reset(struct snd_opl3 * opl3)
+{
+	unsigned short opl3_reg;
+
+	unsigned short reg_side;
+	unsigned char voice_offset;
+
+	int max_voices, i;
+
+	max_voices = (opl3->hardware < OPL3_HW_OPL3) ?
+		MAX_OPL2_VOICES : MAX_OPL3_VOICES;
+
+	for (i = 0; i < max_voices; i++) {
+		/* Get register array side and offset of voice */
+		if (i < MAX_OPL2_VOICES) {
+			/* Left register block for voices 0 .. 8 */
+			reg_side = OPL3_LEFT;
+			voice_offset = i;
+		} else {
+			/* Right register block for voices 9 .. 17 */
+			reg_side = OPL3_RIGHT;
+			voice_offset = i - MAX_OPL2_VOICES;
+		}
+		opl3_reg = reg_side | (OPL3_REG_KSL_LEVEL + snd_opl3_regmap[voice_offset][0]);
+		opl3->command(opl3, opl3_reg, OPL3_TOTAL_LEVEL_MASK); /* Operator 1 volume */
+		opl3_reg = reg_side | (OPL3_REG_KSL_LEVEL + snd_opl3_regmap[voice_offset][1]);
+		opl3->command(opl3, opl3_reg, OPL3_TOTAL_LEVEL_MASK); /* Operator 2 volume */
+
+		opl3_reg = reg_side | (OPL3_REG_KEYON_BLOCK + voice_offset);
+		opl3->command(opl3, opl3_reg, 0x00);	/* Note off */
+	}
+
+	opl3->max_voices = MAX_OPL2_VOICES;
+	opl3->fm_mode = SNDRV_DM_FM_MODE_OPL2;
+
+	opl3->command(opl3, OPL3_LEFT | OPL3_REG_TEST, OPL3_ENABLE_WAVE_SELECT);
+	opl3->command(opl3, OPL3_LEFT | OPL3_REG_PERCUSSION, 0x00);	/* Melodic mode */
+	opl3->rhythm = 0;
+}
+
+EXPORT_SYMBOL(snd_opl3_reset);
+
+static int snd_opl3_play_note(struct snd_opl3 * opl3, struct snd_dm_fm_note * note)
+{
+	unsigned short reg_side;
+	unsigned char voice_offset;
+
+	unsigned short opl3_reg;
+	unsigned char reg_val;
+
+	/* Voices 0 -  8 in OPL2 mode */
+	/* Voices 0 - 17 in OPL3 mode */
+	if (note->voice >= ((opl3->fm_mode == SNDRV_DM_FM_MODE_OPL3) ?
+			    MAX_OPL3_VOICES : MAX_OPL2_VOICES))
+		return -EINVAL;
+
+	/* Get register array side and offset of voice */
+	if (note->voice < MAX_OPL2_VOICES) {
+		/* Left register block for voices 0 .. 8 */
+		reg_side = OPL3_LEFT;
+		voice_offset = note->voice;
+	} else {
+		/* Right register block for voices 9 .. 17 */
+		reg_side = OPL3_RIGHT;
+		voice_offset = note->voice - MAX_OPL2_VOICES;
+	}
+
+	/* Set lower 8 bits of note frequency */
+	reg_val = (unsigned char) note->fnum;
+	opl3_reg = reg_side | (OPL3_REG_FNUM_LOW + voice_offset);
+	opl3->command(opl3, opl3_reg, reg_val);
+	
+	reg_val = 0x00;
+	/* Set output sound flag */
+	if (note->key_on)
+		reg_val |= OPL3_KEYON_BIT;
+	/* Set octave */
+	reg_val |= (note->octave << 2) & OPL3_BLOCKNUM_MASK;
+	/* Set higher 2 bits of note frequency */
+	reg_val |= (unsigned char) (note->fnum >> 8) & OPL3_FNUM_HIGH_MASK;
+
+	/* Set OPL3 KEYON_BLOCK register of requested voice */ 
+	opl3_reg = reg_side | (OPL3_REG_KEYON_BLOCK + voice_offset);
+	opl3->command(opl3, opl3_reg, reg_val);
+
+	return 0;
+}
+
+
+static int snd_opl3_set_voice(struct snd_opl3 * opl3, struct snd_dm_fm_voice * voice)
+{
+	unsigned short reg_side;
+	unsigned char op_offset;
+	unsigned char voice_offset, voice_op;
+
+	unsigned short opl3_reg;
+	unsigned char reg_val;
+
+	/* Only operators 1 and 2 */
+	if (voice->op > 1)
+		return -EINVAL;
+	/* Voices 0 -  8 in OPL2 mode */
+	/* Voices 0 - 17 in OPL3 mode */
+	if (voice->voice >= ((opl3->fm_mode == SNDRV_DM_FM_MODE_OPL3) ?
+			     MAX_OPL3_VOICES : MAX_OPL2_VOICES))
+		return -EINVAL;
+
+	/* Get register array side and offset of voice */
+	if (voice->voice < MAX_OPL2_VOICES) {
+		/* Left register block for voices 0 .. 8 */
+		reg_side = OPL3_LEFT;
+		voice_offset = voice->voice;
+	} else {
+		/* Right register block for voices 9 .. 17 */
+		reg_side = OPL3_RIGHT;
+		voice_offset = voice->voice - MAX_OPL2_VOICES;
+	}
+	/* Get register offset of operator */
+	voice_offset = array_index_nospec(voice_offset, MAX_OPL2_VOICES);
+	voice_op = array_index_nospec(voice->op, 4);
+	op_offset = snd_opl3_regmap[voice_offset][voice_op];
+
+	reg_val = 0x00;
+	/* Set amplitude modulation (tremolo) effect */
+	if (voice->am)
+		reg_val |= OPL3_TREMOLO_ON;
+	/* Set vibrato effect */
+	if (voice->vibrato)
+		reg_val |= OPL3_VIBRATO_ON;
+	/* Set sustaining sound phase */
+	if (voice->do_sustain)
+		reg_val |= OPL3_SUSTAIN_ON;
+	/* Set keyboard scaling bit */ 
+	if (voice->kbd_scale)
+		reg_val |= OPL3_KSR;
+	/* Set harmonic or frequency multiplier */
+	reg_val |= voice->harmonic & OPL3_MULTIPLE_MASK;
+
+	/* Set OPL3 AM_VIB register of requested voice/operator */ 
+	opl3_reg = reg_side | (OPL3_REG_AM_VIB + op_offset);
+	opl3->command(opl3, opl3_reg, reg_val);
+
+	/* Set decreasing volume of higher notes */
+	reg_val = (voice->scale_level << 6) & OPL3_KSL_MASK;
+	/* Set output volume */
+	reg_val |= ~voice->volume & OPL3_TOTAL_LEVEL_MASK;
+
+	/* Set OPL3 KSL_LEVEL register of requested voice/operator */ 
+	opl3_reg = reg_side | (OPL3_REG_KSL_LEVEL + op_offset);
+	opl3->command(opl3, opl3_reg, reg_val);
+
+	/* Set attack phase level */
+	reg_val = (voice->attack << 4) & OPL3_ATTACK_MASK;
+	/* Set decay phase level */
+	reg_val |= voice->decay & OPL3_DECAY_MASK;
+
+	/* Set OPL3 ATTACK_DECAY register of requested voice/operator */ 
+	opl3_reg = reg_side | (OPL3_REG_ATTACK_DECAY + op_offset);
+	opl3->command(opl3, opl3_reg, reg_val);
+
+	/* Set sustain phase level */
+	reg_val = (voice->sustain << 4) & OPL3_SUSTAIN_MASK;
+	/* Set release phase level */
+	reg_val |= voice->release & OPL3_RELEASE_MASK;
+
+	/* Set OPL3 SUSTAIN_RELEASE register of requested voice/operator */ 
+	opl3_reg = reg_side | (OPL3_REG_SUSTAIN_RELEASE + op_offset);
+	opl3->command(opl3, opl3_reg, reg_val);
+
+	/* Set inter-operator feedback */
+	reg_val = (voice->feedback << 1) & OPL3_FEEDBACK_MASK;
+	/* Set inter-operator connection */
+	if (voice->connection)
+		reg_val |= OPL3_CONNECTION_BIT;
+	/* OPL-3 only */
+	if (opl3->fm_mode == SNDRV_DM_FM_MODE_OPL3) {
+		if (voice->left)
+			reg_val |= OPL3_VOICE_TO_LEFT;
+		if (voice->right)
+			reg_val |= OPL3_VOICE_TO_RIGHT;
+	}
+	/* Feedback/connection bits are applicable to voice */
+	opl3_reg = reg_side | (OPL3_REG_FEEDBACK_CONNECTION + voice_offset);
+	opl3->command(opl3, opl3_reg, reg_val);
+
+	/* Select waveform */
+	reg_val = voice->waveform & OPL3_WAVE_SELECT_MASK;
+	opl3_reg = reg_side | (OPL3_REG_WAVE_SELECT + op_offset);
+	opl3->command(opl3, opl3_reg, reg_val);
+
+	return 0;
+}
+
+static int snd_opl3_set_params(struct snd_opl3 * opl3, struct snd_dm_fm_params * params)
+{
+	unsigned char reg_val;
+
+	reg_val = 0x00;
+	/* Set keyboard split method */
+	if (params->kbd_split)
+		reg_val |= OPL3_KEYBOARD_SPLIT;
+	opl3->command(opl3, OPL3_LEFT | OPL3_REG_KBD_SPLIT, reg_val);
+
+	reg_val = 0x00;
+	/* Set amplitude modulation (tremolo) depth */
+	if (params->am_depth)
+		reg_val |= OPL3_TREMOLO_DEPTH;
+	/* Set vibrato depth */
+	if (params->vib_depth)
+		reg_val |= OPL3_VIBRATO_DEPTH;
+	/* Set percussion mode */
+	if (params->rhythm) {
+		reg_val |= OPL3_PERCUSSION_ENABLE;
+		opl3->rhythm = 1;
+	} else {
+		opl3->rhythm = 0;
+	}
+	/* Play percussion instruments */
+	if (params->bass)
+		reg_val |= OPL3_BASSDRUM_ON;
+	if (params->snare)
+		reg_val |= OPL3_SNAREDRUM_ON;
+	if (params->tomtom)
+		reg_val |= OPL3_TOMTOM_ON;
+	if (params->cymbal)
+		reg_val |= OPL3_CYMBAL_ON;
+	if (params->hihat)
+		reg_val |= OPL3_HIHAT_ON;
+
+	opl3->command(opl3, OPL3_LEFT | OPL3_REG_PERCUSSION, reg_val);
+	return 0;
+}
+
+static int snd_opl3_set_mode(struct snd_opl3 * opl3, int mode)
+{
+	if ((mode == SNDRV_DM_FM_MODE_OPL3) && (opl3->hardware < OPL3_HW_OPL3))
+		return -EINVAL;
+
+	opl3->fm_mode = mode;
+	if (opl3->hardware >= OPL3_HW_OPL3)
+		opl3->command(opl3, OPL3_RIGHT | OPL3_REG_CONNECTION_SELECT, 0x00);	/* Clear 4-op connections */
+
+	return 0;
+}
+
+static int snd_opl3_set_connection(struct snd_opl3 * opl3, int connection)
+{
+	unsigned char reg_val;
+
+	/* OPL-3 only */
+	if (opl3->fm_mode != SNDRV_DM_FM_MODE_OPL3)
+		return -EINVAL;
+
+	reg_val = connection & (OPL3_RIGHT_4OP_0 | OPL3_RIGHT_4OP_1 | OPL3_RIGHT_4OP_2 |
+				OPL3_LEFT_4OP_0 | OPL3_LEFT_4OP_1 | OPL3_LEFT_4OP_2);
+	/* Set 4-op connections */
+	opl3->command(opl3, OPL3_RIGHT | OPL3_REG_CONNECTION_SELECT, reg_val);
+
+	return 0;
+}
+