xref: /openbmc/linux/sound/drivers/mpu401/mpu401_uart.c (revision df2634f43f5106947f3735a0b61a6527a4b278cd) 
1 /*
2  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
3  *  Routines for control of MPU-401 in UART mode
4  *
5  *  MPU-401 supports UART mode which is not capable generate transmit
6  *  interrupts thus output is done via polling. Also, if irq < 0, then
7  *  input is done also via polling. Do not expect good performance.
8  *
9  *
10  *   This program is free software; you can redistribute it and/or modify
11  *   it under the terms of the GNU General Public License as published by
12  *   the Free Software Foundation; either version 2 of the License, or
13  *   (at your option) any later version.
14  *
15  *   This program is distributed in the hope that it will be useful,
16  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
17  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18  *   GNU General Public License for more details.
19  *
20  *   You should have received a copy of the GNU General Public License
21  *   along with this program; if not, write to the Free Software
22  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
23  *
24  *   13-03-2003:
25  *      Added support for different kind of hardware I/O. Build in choices
26  *      are port and mmio. For other kind of I/O, set mpu->read and
27  *      mpu->write to your own I/O functions.
28  *
29  */
30 
31 #include <asm/io.h>
32 #include <linux/delay.h>
33 #include <linux/init.h>
34 #include <linux/slab.h>
35 #include <linux/ioport.h>
36 #include <linux/interrupt.h>
37 #include <linux/errno.h>
38 #include <sound/core.h>
39 #include <sound/mpu401.h>
40 
41 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
42 MODULE_DESCRIPTION("Routines for control of MPU-401 in UART mode");
43 MODULE_LICENSE("GPL");
44 
45 static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu);
46 static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu);
47 
48 /*
49 
50  */
51 
52 #define snd_mpu401_input_avail(mpu) \
53 	(!(mpu->read(mpu, MPU401C(mpu)) & MPU401_RX_EMPTY))
54 #define snd_mpu401_output_ready(mpu) \
55 	(!(mpu->read(mpu, MPU401C(mpu)) & MPU401_TX_FULL))
56 
57 /* Build in lowlevel io */
58 static void mpu401_write_port(struct snd_mpu401 *mpu, unsigned char data,
59 			      unsigned long addr)
60 {
61 	outb(data, addr);
62 }
63 
64 static unsigned char mpu401_read_port(struct snd_mpu401 *mpu,
65 				      unsigned long addr)
66 {
67 	return inb(addr);
68 }
69 
70 static void mpu401_write_mmio(struct snd_mpu401 *mpu, unsigned char data,
71 			      unsigned long addr)
72 {
73 	writeb(data, (void __iomem *)addr);
74 }
75 
76 static unsigned char mpu401_read_mmio(struct snd_mpu401 *mpu,
77 				      unsigned long addr)
78 {
79 	return readb((void __iomem *)addr);
80 }
81 /*  */
82 
83 static void snd_mpu401_uart_clear_rx(struct snd_mpu401 *mpu)
84 {
85 	int timeout = 100000;
86 	for (; timeout > 0 && snd_mpu401_input_avail(mpu); timeout--)
87 		mpu->read(mpu, MPU401D(mpu));
88 #ifdef CONFIG_SND_DEBUG
89 	if (timeout <= 0)
90 		snd_printk(KERN_ERR "cmd: clear rx timeout (status = 0x%x)\n",
91 			   mpu->read(mpu, MPU401C(mpu)));
92 #endif
93 }
94 
95 static void uart_interrupt_tx(struct snd_mpu401 *mpu)
96 {
97 	unsigned long flags;
98 
99 	if (test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode) &&
100 	    test_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode)) {
101 		spin_lock_irqsave(&mpu->output_lock, flags);
102 		snd_mpu401_uart_output_write(mpu);
103 		spin_unlock_irqrestore(&mpu->output_lock, flags);
104 	}
105 }
106 
107 static void _snd_mpu401_uart_interrupt(struct snd_mpu401 *mpu)
108 {
109 	unsigned long flags;
110 
111 	if (mpu->info_flags & MPU401_INFO_INPUT) {
112 		spin_lock_irqsave(&mpu->input_lock, flags);
113 		if (test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
114 			snd_mpu401_uart_input_read(mpu);
115 		else
116 			snd_mpu401_uart_clear_rx(mpu);
117 		spin_unlock_irqrestore(&mpu->input_lock, flags);
118 	}
119 	if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
120 		/* ok. for better Tx performance try do some output
121 		   when input is done */
122 		uart_interrupt_tx(mpu);
123 }
124 
125 /**
126  * snd_mpu401_uart_interrupt - generic MPU401-UART interrupt handler
127  * @irq: the irq number
128  * @dev_id: mpu401 instance
129  *
130  * Processes the interrupt for MPU401-UART i/o.
131  */
132 irqreturn_t snd_mpu401_uart_interrupt(int irq, void *dev_id)
133 {
134 	struct snd_mpu401 *mpu = dev_id;
135 
136 	if (mpu == NULL)
137 		return IRQ_NONE;
138 	_snd_mpu401_uart_interrupt(mpu);
139 	return IRQ_HANDLED;
140 }
141 
142 EXPORT_SYMBOL(snd_mpu401_uart_interrupt);
143 
144 /**
145  * snd_mpu401_uart_interrupt_tx - generic MPU401-UART transmit irq handler
146  * @irq: the irq number
147  * @dev_id: mpu401 instance
148  *
149  * Processes the interrupt for MPU401-UART output.
150  */
151 irqreturn_t snd_mpu401_uart_interrupt_tx(int irq, void *dev_id)
152 {
153 	struct snd_mpu401 *mpu = dev_id;
154 
155 	if (mpu == NULL)
156 		return IRQ_NONE;
157 	uart_interrupt_tx(mpu);
158 	return IRQ_HANDLED;
159 }
160 
161 EXPORT_SYMBOL(snd_mpu401_uart_interrupt_tx);
162 
163 /*
164  * timer callback
165  * reprogram the timer and call the interrupt job
166  */
167 static void snd_mpu401_uart_timer(unsigned long data)
168 {
169 	struct snd_mpu401 *mpu = (struct snd_mpu401 *)data;
170 	unsigned long flags;
171 
172 	spin_lock_irqsave(&mpu->timer_lock, flags);
173 	/*mpu->mode |= MPU401_MODE_TIMER;*/
174 	mpu->timer.expires = 1 + jiffies;
175 	add_timer(&mpu->timer);
176 	spin_unlock_irqrestore(&mpu->timer_lock, flags);
177 	if (mpu->rmidi)
178 		_snd_mpu401_uart_interrupt(mpu);
179 }
180 
181 /*
182  * initialize the timer callback if not programmed yet
183  */
184 static void snd_mpu401_uart_add_timer (struct snd_mpu401 *mpu, int input)
185 {
186 	unsigned long flags;
187 
188 	spin_lock_irqsave (&mpu->timer_lock, flags);
189 	if (mpu->timer_invoked == 0) {
190 		init_timer(&mpu->timer);
191 		mpu->timer.data = (unsigned long)mpu;
192 		mpu->timer.function = snd_mpu401_uart_timer;
193 		mpu->timer.expires = 1 + jiffies;
194 		add_timer(&mpu->timer);
195 	}
196 	mpu->timer_invoked |= input ? MPU401_MODE_INPUT_TIMER :
197 		MPU401_MODE_OUTPUT_TIMER;
198 	spin_unlock_irqrestore (&mpu->timer_lock, flags);
199 }
200 
201 /*
202  * remove the timer callback if still active
203  */
204 static void snd_mpu401_uart_remove_timer (struct snd_mpu401 *mpu, int input)
205 {
206 	unsigned long flags;
207 
208 	spin_lock_irqsave (&mpu->timer_lock, flags);
209 	if (mpu->timer_invoked) {
210 		mpu->timer_invoked &= input ? ~MPU401_MODE_INPUT_TIMER :
211 			~MPU401_MODE_OUTPUT_TIMER;
212 		if (! mpu->timer_invoked)
213 			del_timer(&mpu->timer);
214 	}
215 	spin_unlock_irqrestore (&mpu->timer_lock, flags);
216 }
217 
218 /*
219  * send a UART command
220  * return zero if successful, non-zero for some errors
221  */
222 
223 static int snd_mpu401_uart_cmd(struct snd_mpu401 * mpu, unsigned char cmd,
224 			       int ack)
225 {
226 	unsigned long flags;
227 	int timeout, ok;
228 
229 	spin_lock_irqsave(&mpu->input_lock, flags);
230 	if (mpu->hardware != MPU401_HW_TRID4DWAVE) {
231 		mpu->write(mpu, 0x00, MPU401D(mpu));
232 		/*snd_mpu401_uart_clear_rx(mpu);*/
233 	}
234 	/* ok. standard MPU-401 initialization */
235 	if (mpu->hardware != MPU401_HW_SB) {
236 		for (timeout = 1000; timeout > 0 &&
237 			     !snd_mpu401_output_ready(mpu); timeout--)
238 			udelay(10);
239 #ifdef CONFIG_SND_DEBUG
240 		if (!timeout)
241 			snd_printk(KERN_ERR "cmd: tx timeout (status = 0x%x)\n",
242 				   mpu->read(mpu, MPU401C(mpu)));
243 #endif
244 	}
245 	mpu->write(mpu, cmd, MPU401C(mpu));
246 	if (ack && !(mpu->info_flags & MPU401_INFO_NO_ACK)) {
247 		ok = 0;
248 		timeout = 10000;
249 		while (!ok && timeout-- > 0) {
250 			if (snd_mpu401_input_avail(mpu)) {
251 				if (mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
252 					ok = 1;
253 			}
254 		}
255 		if (!ok && mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
256 			ok = 1;
257 	} else
258 		ok = 1;
259 	spin_unlock_irqrestore(&mpu->input_lock, flags);
260 	if (!ok) {
261 		snd_printk(KERN_ERR "cmd: 0x%x failed at 0x%lx "
262 			   "(status = 0x%x, data = 0x%x)\n", cmd, mpu->port,
263 			   mpu->read(mpu, MPU401C(mpu)),
264 			   mpu->read(mpu, MPU401D(mpu)));
265 		return 1;
266 	}
267 	return 0;
268 }
269 
270 static int snd_mpu401_do_reset(struct snd_mpu401 *mpu)
271 {
272 	if (snd_mpu401_uart_cmd(mpu, MPU401_RESET, 1))
273 		return -EIO;
274 	if (snd_mpu401_uart_cmd(mpu, MPU401_ENTER_UART, 0))
275 		return -EIO;
276 	return 0;
277 }
278 
279 /*
280  * input/output open/close - protected by open_mutex in rawmidi.c
281  */
282 static int snd_mpu401_uart_input_open(struct snd_rawmidi_substream *substream)
283 {
284 	struct snd_mpu401 *mpu;
285 	int err;
286 
287 	mpu = substream->rmidi->private_data;
288 	if (mpu->open_input && (err = mpu->open_input(mpu)) < 0)
289 		return err;
290 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode)) {
291 		if (snd_mpu401_do_reset(mpu) < 0)
292 			goto error_out;
293 	}
294 	mpu->substream_input = substream;
295 	set_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
296 	return 0;
297 
298 error_out:
299 	if (mpu->open_input && mpu->close_input)
300 		mpu->close_input(mpu);
301 	return -EIO;
302 }
303 
304 static int snd_mpu401_uart_output_open(struct snd_rawmidi_substream *substream)
305 {
306 	struct snd_mpu401 *mpu;
307 	int err;
308 
309 	mpu = substream->rmidi->private_data;
310 	if (mpu->open_output && (err = mpu->open_output(mpu)) < 0)
311 		return err;
312 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode)) {
313 		if (snd_mpu401_do_reset(mpu) < 0)
314 			goto error_out;
315 	}
316 	mpu->substream_output = substream;
317 	set_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
318 	return 0;
319 
320 error_out:
321 	if (mpu->open_output && mpu->close_output)
322 		mpu->close_output(mpu);
323 	return -EIO;
324 }
325 
326 static int snd_mpu401_uart_input_close(struct snd_rawmidi_substream *substream)
327 {
328 	struct snd_mpu401 *mpu;
329 	int err = 0;
330 
331 	mpu = substream->rmidi->private_data;
332 	clear_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
333 	mpu->substream_input = NULL;
334 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode))
335 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
336 	if (mpu->close_input)
337 		mpu->close_input(mpu);
338 	if (err)
339 		return -EIO;
340 	return 0;
341 }
342 
343 static int snd_mpu401_uart_output_close(struct snd_rawmidi_substream *substream)
344 {
345 	struct snd_mpu401 *mpu;
346 	int err = 0;
347 
348 	mpu = substream->rmidi->private_data;
349 	clear_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
350 	mpu->substream_output = NULL;
351 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
352 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
353 	if (mpu->close_output)
354 		mpu->close_output(mpu);
355 	if (err)
356 		return -EIO;
357 	return 0;
358 }
359 
360 /*
361  * trigger input callback
362  */
363 static void
364 snd_mpu401_uart_input_trigger(struct snd_rawmidi_substream *substream, int up)
365 {
366 	unsigned long flags;
367 	struct snd_mpu401 *mpu;
368 	int max = 64;
369 
370 	mpu = substream->rmidi->private_data;
371 	if (up) {
372 		if (! test_and_set_bit(MPU401_MODE_BIT_INPUT_TRIGGER,
373 				       &mpu->mode)) {
374 			/* first time - flush FIFO */
375 			while (max-- > 0)
376 				mpu->read(mpu, MPU401D(mpu));
377 			if (mpu->irq < 0)
378 				snd_mpu401_uart_add_timer(mpu, 1);
379 		}
380 
381 		/* read data in advance */
382 		spin_lock_irqsave(&mpu->input_lock, flags);
383 		snd_mpu401_uart_input_read(mpu);
384 		spin_unlock_irqrestore(&mpu->input_lock, flags);
385 	} else {
386 		if (mpu->irq < 0)
387 			snd_mpu401_uart_remove_timer(mpu, 1);
388 		clear_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode);
389 	}
390 
391 }
392 
393 /*
394  * transfer input pending data
395  * call with input_lock spinlock held
396  */
397 static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu)
398 {
399 	int max = 128;
400 	unsigned char byte;
401 
402 	while (max-- > 0) {
403 		if (! snd_mpu401_input_avail(mpu))
404 			break; /* input not available */
405 		byte = mpu->read(mpu, MPU401D(mpu));
406 		if (test_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode))
407 			snd_rawmidi_receive(mpu->substream_input, &byte, 1);
408 	}
409 }
410 
411 /*
412  *  Tx FIFO sizes:
413  *    CS4237B			- 16 bytes
414  *    AudioDrive ES1688         - 12 bytes
415  *    S3 SonicVibes             -  8 bytes
416  *    SoundBlaster AWE 64       -  2 bytes (ugly hardware)
417  */
418 
419 /*
420  * write output pending bytes
421  * call with output_lock spinlock held
422  */
423 static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu)
424 {
425 	unsigned char byte;
426 	int max = 256;
427 
428 	do {
429 		if (snd_rawmidi_transmit_peek(mpu->substream_output,
430 					      &byte, 1) == 1) {
431 			/*
432 			 * Try twice because there is hardware that insists on
433 			 * setting the output busy bit after each write.
434 			 */
435 			if (!snd_mpu401_output_ready(mpu) &&
436 			    !snd_mpu401_output_ready(mpu))
437 				break;	/* Tx FIFO full - try again later */
438 			mpu->write(mpu, byte, MPU401D(mpu));
439 			snd_rawmidi_transmit_ack(mpu->substream_output, 1);
440 		} else {
441 			snd_mpu401_uart_remove_timer (mpu, 0);
442 			break;	/* no other data - leave the tx loop */
443 		}
444 	} while (--max > 0);
445 }
446 
447 /*
448  * output trigger callback
449  */
450 static void
451 snd_mpu401_uart_output_trigger(struct snd_rawmidi_substream *substream, int up)
452 {
453 	unsigned long flags;
454 	struct snd_mpu401 *mpu;
455 
456 	mpu = substream->rmidi->private_data;
457 	if (up) {
458 		set_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);
459 
460 		/* try to add the timer at each output trigger,
461 		 * since the output timer might have been removed in
462 		 * snd_mpu401_uart_output_write().
463 		 */
464 		if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
465 			snd_mpu401_uart_add_timer(mpu, 0);
466 
467 		/* output pending data */
468 		spin_lock_irqsave(&mpu->output_lock, flags);
469 		snd_mpu401_uart_output_write(mpu);
470 		spin_unlock_irqrestore(&mpu->output_lock, flags);
471 	} else {
472 		if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
473 			snd_mpu401_uart_remove_timer(mpu, 0);
474 		clear_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);
475 	}
476 }
477 
478 /*
479 
480  */
481 
482 static struct snd_rawmidi_ops snd_mpu401_uart_output =
483 {
484 	.open =		snd_mpu401_uart_output_open,
485 	.close =	snd_mpu401_uart_output_close,
486 	.trigger =	snd_mpu401_uart_output_trigger,
487 };
488 
489 static struct snd_rawmidi_ops snd_mpu401_uart_input =
490 {
491 	.open =		snd_mpu401_uart_input_open,
492 	.close =	snd_mpu401_uart_input_close,
493 	.trigger =	snd_mpu401_uart_input_trigger,
494 };
495 
496 static void snd_mpu401_uart_free(struct snd_rawmidi *rmidi)
497 {
498 	struct snd_mpu401 *mpu = rmidi->private_data;
499 	if (mpu->irq_flags && mpu->irq >= 0)
500 		free_irq(mpu->irq, (void *) mpu);
501 	release_and_free_resource(mpu->res);
502 	kfree(mpu);
503 }
504 
505 /**
506  * snd_mpu401_uart_new - create an MPU401-UART instance
507  * @card: the card instance
508  * @device: the device index, zero-based
509  * @hardware: the hardware type, MPU401_HW_XXXX
510  * @port: the base address of MPU401 port
511  * @info_flags: bitflags MPU401_INFO_XXX
512  * @irq: the irq number, -1 if no interrupt for mpu
513  * @irq_flags: the irq request flags (SA_XXX), 0 if irq was already reserved.
514  * @rrawmidi: the pointer to store the new rawmidi instance
515  *
516  * Creates a new MPU-401 instance.
517  *
518  * Note that the rawmidi instance is returned on the rrawmidi argument,
519  * not the mpu401 instance itself.  To access to the mpu401 instance,
520  * cast from rawmidi->private_data (with struct snd_mpu401 magic-cast).
521  *
522  * Returns zero if successful, or a negative error code.
523  */
524 int snd_mpu401_uart_new(struct snd_card *card, int device,
525 			unsigned short hardware,
526 			unsigned long port,
527 			unsigned int info_flags,
528 			int irq, int irq_flags,
529 			struct snd_rawmidi ** rrawmidi)
530 {
531 	struct snd_mpu401 *mpu;
532 	struct snd_rawmidi *rmidi;
533 	int in_enable, out_enable;
534 	int err;
535 
536 	if (rrawmidi)
537 		*rrawmidi = NULL;
538 	if (! (info_flags & (MPU401_INFO_INPUT | MPU401_INFO_OUTPUT)))
539 		info_flags |= MPU401_INFO_INPUT | MPU401_INFO_OUTPUT;
540 	in_enable = (info_flags & MPU401_INFO_INPUT) ? 1 : 0;
541 	out_enable = (info_flags & MPU401_INFO_OUTPUT) ? 1 : 0;
542 	if ((err = snd_rawmidi_new(card, "MPU-401U", device,
543 				   out_enable, in_enable, &rmidi)) < 0)
544 		return err;
545 	mpu = kzalloc(sizeof(*mpu), GFP_KERNEL);
546 	if (mpu == NULL) {
547 		snd_printk(KERN_ERR "mpu401_uart: cannot allocate\n");
548 		snd_device_free(card, rmidi);
549 		return -ENOMEM;
550 	}
551 	rmidi->private_data = mpu;
552 	rmidi->private_free = snd_mpu401_uart_free;
553 	spin_lock_init(&mpu->input_lock);
554 	spin_lock_init(&mpu->output_lock);
555 	spin_lock_init(&mpu->timer_lock);
556 	mpu->hardware = hardware;
557 	if (! (info_flags & MPU401_INFO_INTEGRATED)) {
558 		int res_size = hardware == MPU401_HW_PC98II ? 4 : 2;
559 		mpu->res = request_region(port, res_size, "MPU401 UART");
560 		if (mpu->res == NULL) {
561 			snd_printk(KERN_ERR "mpu401_uart: "
562 				   "unable to grab port 0x%lx size %d\n",
563 				   port, res_size);
564 			snd_device_free(card, rmidi);
565 			return -EBUSY;
566 		}
567 	}
568 	if (info_flags & MPU401_INFO_MMIO) {
569 		mpu->write = mpu401_write_mmio;
570 		mpu->read = mpu401_read_mmio;
571 	} else {
572 		mpu->write = mpu401_write_port;
573 		mpu->read = mpu401_read_port;
574 	}
575 	mpu->port = port;
576 	if (hardware == MPU401_HW_PC98II)
577 		mpu->cport = port + 2;
578 	else
579 		mpu->cport = port + 1;
580 	if (irq >= 0 && irq_flags) {
581 		if (request_irq(irq, snd_mpu401_uart_interrupt, irq_flags,
582 				"MPU401 UART", (void *) mpu)) {
583 			snd_printk(KERN_ERR "mpu401_uart: "
584 				   "unable to grab IRQ %d\n", irq);
585 			snd_device_free(card, rmidi);
586 			return -EBUSY;
587 		}
588 	}
589 	mpu->info_flags = info_flags;
590 	mpu->irq = irq;
591 	mpu->irq_flags = irq_flags;
592 	if (card->shortname[0])
593 		snprintf(rmidi->name, sizeof(rmidi->name), "%s MIDI",
594 			 card->shortname);
595 	else
596 		sprintf(rmidi->name, "MPU-401 MIDI %d-%d",card->number, device);
597 	if (out_enable) {
598 		snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
599 				    &snd_mpu401_uart_output);
600 		rmidi->info_flags |= SNDRV_RAWMIDI_INFO_OUTPUT;
601 	}
602 	if (in_enable) {
603 		snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT,
604 				    &snd_mpu401_uart_input);
605 		rmidi->info_flags |= SNDRV_RAWMIDI_INFO_INPUT;
606 		if (out_enable)
607 			rmidi->info_flags |= SNDRV_RAWMIDI_INFO_DUPLEX;
608 	}
609 	mpu->rmidi = rmidi;
610 	if (rrawmidi)
611 		*rrawmidi = rmidi;
612 	return 0;
613 }
614 
615 EXPORT_SYMBOL(snd_mpu401_uart_new);
616 
617 /*
618  *  INIT part
619  */
620 
621 static int __init alsa_mpu401_uart_init(void)
622 {
623 	return 0;
624 }
625 
626 static void __exit alsa_mpu401_uart_exit(void)
627 {
628 }
629 
630 module_init(alsa_mpu401_uart_init)
631 module_exit(alsa_mpu401_uart_exit)
632