xref: /linux/sound/drivers/mpu401/mpu401_uart.c (revision bfd5bb6f90af092aa345b15cd78143956a13c2a8) 
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. Without interrupt,
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 <linux/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/module.h>
37 #include <linux/interrupt.h>
38 #include <linux/errno.h>
39 #include <sound/core.h>
40 #include <sound/mpu401.h>
41 
42 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
43 MODULE_DESCRIPTION("Routines for control of MPU-401 in UART mode");
44 MODULE_LICENSE("GPL");
45 
46 static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu);
47 static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu);
48 
49 /*
50 
51  */
52 
53 #define snd_mpu401_input_avail(mpu) \
54 	(!(mpu->read(mpu, MPU401C(mpu)) & MPU401_RX_EMPTY))
55 #define snd_mpu401_output_ready(mpu) \
56 	(!(mpu->read(mpu, MPU401C(mpu)) & MPU401_TX_FULL))
57 
58 /* Build in lowlevel io */
59 static void mpu401_write_port(struct snd_mpu401 *mpu, unsigned char data,
60 			      unsigned long addr)
61 {
62 	outb(data, addr);
63 }
64 
65 static unsigned char mpu401_read_port(struct snd_mpu401 *mpu,
66 				      unsigned long addr)
67 {
68 	return inb(addr);
69 }
70 
71 static void mpu401_write_mmio(struct snd_mpu401 *mpu, unsigned char data,
72 			      unsigned long addr)
73 {
74 	writeb(data, (void __iomem *)addr);
75 }
76 
77 static unsigned char mpu401_read_mmio(struct snd_mpu401 *mpu,
78 				      unsigned long addr)
79 {
80 	return readb((void __iomem *)addr);
81 }
82 /*  */
83 
84 static void snd_mpu401_uart_clear_rx(struct snd_mpu401 *mpu)
85 {
86 	int timeout = 100000;
87 	for (; timeout > 0 && snd_mpu401_input_avail(mpu); timeout--)
88 		mpu->read(mpu, MPU401D(mpu));
89 #ifdef CONFIG_SND_DEBUG
90 	if (timeout <= 0)
91 		snd_printk(KERN_ERR "cmd: clear rx timeout (status = 0x%x)\n",
92 			   mpu->read(mpu, MPU401C(mpu)));
93 #endif
94 }
95 
96 static void uart_interrupt_tx(struct snd_mpu401 *mpu)
97 {
98 	unsigned long flags;
99 
100 	if (test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode) &&
101 	    test_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode)) {
102 		spin_lock_irqsave(&mpu->output_lock, flags);
103 		snd_mpu401_uart_output_write(mpu);
104 		spin_unlock_irqrestore(&mpu->output_lock, flags);
105 	}
106 }
107 
108 static void _snd_mpu401_uart_interrupt(struct snd_mpu401 *mpu)
109 {
110 	unsigned long flags;
111 
112 	if (mpu->info_flags & MPU401_INFO_INPUT) {
113 		spin_lock_irqsave(&mpu->input_lock, flags);
114 		if (test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
115 			snd_mpu401_uart_input_read(mpu);
116 		else
117 			snd_mpu401_uart_clear_rx(mpu);
118 		spin_unlock_irqrestore(&mpu->input_lock, flags);
119 	}
120 	if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
121 		/* ok. for better Tx performance try do some output
122 		   when input is done */
123 		uart_interrupt_tx(mpu);
124 }
125 
126 /**
127  * snd_mpu401_uart_interrupt - generic MPU401-UART interrupt handler
128  * @irq: the irq number
129  * @dev_id: mpu401 instance
130  *
131  * Processes the interrupt for MPU401-UART i/o.
132  *
133  * Return: %IRQ_HANDLED if the interrupt was handled. %IRQ_NONE otherwise.
134  */
135 irqreturn_t snd_mpu401_uart_interrupt(int irq, void *dev_id)
136 {
137 	struct snd_mpu401 *mpu = dev_id;
138 
139 	if (!mpu)
140 		return IRQ_NONE;
141 	_snd_mpu401_uart_interrupt(mpu);
142 	return IRQ_HANDLED;
143 }
144 
145 EXPORT_SYMBOL(snd_mpu401_uart_interrupt);
146 
147 /**
148  * snd_mpu401_uart_interrupt_tx - generic MPU401-UART transmit irq handler
149  * @irq: the irq number
150  * @dev_id: mpu401 instance
151  *
152  * Processes the interrupt for MPU401-UART output.
153  *
154  * Return: %IRQ_HANDLED if the interrupt was handled. %IRQ_NONE otherwise.
155  */
156 irqreturn_t snd_mpu401_uart_interrupt_tx(int irq, void *dev_id)
157 {
158 	struct snd_mpu401 *mpu = dev_id;
159 
160 	if (!mpu)
161 		return IRQ_NONE;
162 	uart_interrupt_tx(mpu);
163 	return IRQ_HANDLED;
164 }
165 
166 EXPORT_SYMBOL(snd_mpu401_uart_interrupt_tx);
167 
168 /*
169  * timer callback
170  * reprogram the timer and call the interrupt job
171  */
172 static void snd_mpu401_uart_timer(struct timer_list *t)
173 {
174 	struct snd_mpu401 *mpu = from_timer(mpu, t, timer);
175 	unsigned long flags;
176 
177 	spin_lock_irqsave(&mpu->timer_lock, flags);
178 	/*mpu->mode |= MPU401_MODE_TIMER;*/
179 	mod_timer(&mpu->timer,  1 + jiffies);
180 	spin_unlock_irqrestore(&mpu->timer_lock, flags);
181 	if (mpu->rmidi)
182 		_snd_mpu401_uart_interrupt(mpu);
183 }
184 
185 /*
186  * initialize the timer callback if not programmed yet
187  */
188 static void snd_mpu401_uart_add_timer (struct snd_mpu401 *mpu, int input)
189 {
190 	unsigned long flags;
191 
192 	spin_lock_irqsave (&mpu->timer_lock, flags);
193 	if (mpu->timer_invoked == 0) {
194 		timer_setup(&mpu->timer, snd_mpu401_uart_timer, 0);
195 		mod_timer(&mpu->timer, 1 + jiffies);
196 	}
197 	mpu->timer_invoked |= input ? MPU401_MODE_INPUT_TIMER :
198 		MPU401_MODE_OUTPUT_TIMER;
199 	spin_unlock_irqrestore (&mpu->timer_lock, flags);
200 }
201 
202 /*
203  * remove the timer callback if still active
204  */
205 static void snd_mpu401_uart_remove_timer (struct snd_mpu401 *mpu, int input)
206 {
207 	unsigned long flags;
208 
209 	spin_lock_irqsave (&mpu->timer_lock, flags);
210 	if (mpu->timer_invoked) {
211 		mpu->timer_invoked &= input ? ~MPU401_MODE_INPUT_TIMER :
212 			~MPU401_MODE_OUTPUT_TIMER;
213 		if (! mpu->timer_invoked)
214 			del_timer(&mpu->timer);
215 	}
216 	spin_unlock_irqrestore (&mpu->timer_lock, flags);
217 }
218 
219 /*
220  * send a UART command
221  * return zero if successful, non-zero for some errors
222  */
223 
224 static int snd_mpu401_uart_cmd(struct snd_mpu401 * mpu, unsigned char cmd,
225 			       int ack)
226 {
227 	unsigned long flags;
228 	int timeout, ok;
229 
230 	spin_lock_irqsave(&mpu->input_lock, flags);
231 	if (mpu->hardware != MPU401_HW_TRID4DWAVE) {
232 		mpu->write(mpu, 0x00, MPU401D(mpu));
233 		/*snd_mpu401_uart_clear_rx(mpu);*/
234 	}
235 	/* ok. standard MPU-401 initialization */
236 	if (mpu->hardware != MPU401_HW_SB) {
237 		for (timeout = 1000; timeout > 0 &&
238 			     !snd_mpu401_output_ready(mpu); timeout--)
239 			udelay(10);
240 #ifdef CONFIG_SND_DEBUG
241 		if (!timeout)
242 			snd_printk(KERN_ERR "cmd: tx timeout (status = 0x%x)\n",
243 				   mpu->read(mpu, MPU401C(mpu)));
244 #endif
245 	}
246 	mpu->write(mpu, cmd, MPU401C(mpu));
247 	if (ack && !(mpu->info_flags & MPU401_INFO_NO_ACK)) {
248 		ok = 0;
249 		timeout = 10000;
250 		while (!ok && timeout-- > 0) {
251 			if (snd_mpu401_input_avail(mpu)) {
252 				if (mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
253 					ok = 1;
254 			}
255 		}
256 		if (!ok && mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
257 			ok = 1;
258 	} else
259 		ok = 1;
260 	spin_unlock_irqrestore(&mpu->input_lock, flags);
261 	if (!ok) {
262 		snd_printk(KERN_ERR "cmd: 0x%x failed at 0x%lx "
263 			   "(status = 0x%x, data = 0x%x)\n", cmd, mpu->port,
264 			   mpu->read(mpu, MPU401C(mpu)),
265 			   mpu->read(mpu, MPU401D(mpu)));
266 		return 1;
267 	}
268 	return 0;
269 }
270 
271 static int snd_mpu401_do_reset(struct snd_mpu401 *mpu)
272 {
273 	if (snd_mpu401_uart_cmd(mpu, MPU401_RESET, 1))
274 		return -EIO;
275 	if (snd_mpu401_uart_cmd(mpu, MPU401_ENTER_UART, 0))
276 		return -EIO;
277 	return 0;
278 }
279 
280 /*
281  * input/output open/close - protected by open_mutex in rawmidi.c
282  */
283 static int snd_mpu401_uart_input_open(struct snd_rawmidi_substream *substream)
284 {
285 	struct snd_mpu401 *mpu;
286 	int err;
287 
288 	mpu = substream->rmidi->private_data;
289 	if (mpu->open_input && (err = mpu->open_input(mpu)) < 0)
290 		return err;
291 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode)) {
292 		if (snd_mpu401_do_reset(mpu) < 0)
293 			goto error_out;
294 	}
295 	mpu->substream_input = substream;
296 	set_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
297 	return 0;
298 
299 error_out:
300 	if (mpu->open_input && mpu->close_input)
301 		mpu->close_input(mpu);
302 	return -EIO;
303 }
304 
305 static int snd_mpu401_uart_output_open(struct snd_rawmidi_substream *substream)
306 {
307 	struct snd_mpu401 *mpu;
308 	int err;
309 
310 	mpu = substream->rmidi->private_data;
311 	if (mpu->open_output && (err = mpu->open_output(mpu)) < 0)
312 		return err;
313 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode)) {
314 		if (snd_mpu401_do_reset(mpu) < 0)
315 			goto error_out;
316 	}
317 	mpu->substream_output = substream;
318 	set_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
319 	return 0;
320 
321 error_out:
322 	if (mpu->open_output && mpu->close_output)
323 		mpu->close_output(mpu);
324 	return -EIO;
325 }
326 
327 static int snd_mpu401_uart_input_close(struct snd_rawmidi_substream *substream)
328 {
329 	struct snd_mpu401 *mpu;
330 	int err = 0;
331 
332 	mpu = substream->rmidi->private_data;
333 	clear_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
334 	mpu->substream_input = NULL;
335 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode))
336 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
337 	if (mpu->close_input)
338 		mpu->close_input(mpu);
339 	if (err)
340 		return -EIO;
341 	return 0;
342 }
343 
344 static int snd_mpu401_uart_output_close(struct snd_rawmidi_substream *substream)
345 {
346 	struct snd_mpu401 *mpu;
347 	int err = 0;
348 
349 	mpu = substream->rmidi->private_data;
350 	clear_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
351 	mpu->substream_output = NULL;
352 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
353 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
354 	if (mpu->close_output)
355 		mpu->close_output(mpu);
356 	if (err)
357 		return -EIO;
358 	return 0;
359 }
360 
361 /*
362  * trigger input callback
363  */
364 static void
365 snd_mpu401_uart_input_trigger(struct snd_rawmidi_substream *substream, int up)
366 {
367 	unsigned long flags;
368 	struct snd_mpu401 *mpu;
369 	int max = 64;
370 
371 	mpu = substream->rmidi->private_data;
372 	if (up) {
373 		if (! test_and_set_bit(MPU401_MODE_BIT_INPUT_TRIGGER,
374 				       &mpu->mode)) {
375 			/* first time - flush FIFO */
376 			while (max-- > 0)
377 				mpu->read(mpu, MPU401D(mpu));
378 			if (mpu->info_flags & MPU401_INFO_USE_TIMER)
379 				snd_mpu401_uart_add_timer(mpu, 1);
380 		}
381 
382 		/* read data in advance */
383 		spin_lock_irqsave(&mpu->input_lock, flags);
384 		snd_mpu401_uart_input_read(mpu);
385 		spin_unlock_irqrestore(&mpu->input_lock, flags);
386 	} else {
387 		if (mpu->info_flags & MPU401_INFO_USE_TIMER)
388 			snd_mpu401_uart_remove_timer(mpu, 1);
389 		clear_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode);
390 	}
391 
392 }
393 
394 /*
395  * transfer input pending data
396  * call with input_lock spinlock held
397  */
398 static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu)
399 {
400 	int max = 128;
401 	unsigned char byte;
402 
403 	while (max-- > 0) {
404 		if (! snd_mpu401_input_avail(mpu))
405 			break; /* input not available */
406 		byte = mpu->read(mpu, MPU401D(mpu));
407 		if (test_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode))
408 			snd_rawmidi_receive(mpu->substream_input, &byte, 1);
409 	}
410 }
411 
412 /*
413  *  Tx FIFO sizes:
414  *    CS4237B			- 16 bytes
415  *    AudioDrive ES1688         - 12 bytes
416  *    S3 SonicVibes             -  8 bytes
417  *    SoundBlaster AWE 64       -  2 bytes (ugly hardware)
418  */
419 
420 /*
421  * write output pending bytes
422  * call with output_lock spinlock held
423  */
424 static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu)
425 {
426 	unsigned char byte;
427 	int max = 256;
428 
429 	do {
430 		if (snd_rawmidi_transmit_peek(mpu->substream_output,
431 					      &byte, 1) == 1) {
432 			/*
433 			 * Try twice because there is hardware that insists on
434 			 * setting the output busy bit after each write.
435 			 */
436 			if (!snd_mpu401_output_ready(mpu) &&
437 			    !snd_mpu401_output_ready(mpu))
438 				break;	/* Tx FIFO full - try again later */
439 			mpu->write(mpu, byte, MPU401D(mpu));
440 			snd_rawmidi_transmit_ack(mpu->substream_output, 1);
441 		} else {
442 			snd_mpu401_uart_remove_timer (mpu, 0);
443 			break;	/* no other data - leave the tx loop */
444 		}
445 	} while (--max > 0);
446 }
447 
448 /*
449  * output trigger callback
450  */
451 static void
452 snd_mpu401_uart_output_trigger(struct snd_rawmidi_substream *substream, int up)
453 {
454 	unsigned long flags;
455 	struct snd_mpu401 *mpu;
456 
457 	mpu = substream->rmidi->private_data;
458 	if (up) {
459 		set_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);
460 
461 		/* try to add the timer at each output trigger,
462 		 * since the output timer might have been removed in
463 		 * snd_mpu401_uart_output_write().
464 		 */
465 		if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
466 			snd_mpu401_uart_add_timer(mpu, 0);
467 
468 		/* output pending data */
469 		spin_lock_irqsave(&mpu->output_lock, flags);
470 		snd_mpu401_uart_output_write(mpu);
471 		spin_unlock_irqrestore(&mpu->output_lock, flags);
472 	} else {
473 		if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
474 			snd_mpu401_uart_remove_timer(mpu, 0);
475 		clear_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);
476 	}
477 }
478 
479 /*
480 
481  */
482 
483 static const struct snd_rawmidi_ops snd_mpu401_uart_output =
484 {
485 	.open =		snd_mpu401_uart_output_open,
486 	.close =	snd_mpu401_uart_output_close,
487 	.trigger =	snd_mpu401_uart_output_trigger,
488 };
489 
490 static const struct snd_rawmidi_ops snd_mpu401_uart_input =
491 {
492 	.open =		snd_mpu401_uart_input_open,
493 	.close =	snd_mpu401_uart_input_close,
494 	.trigger =	snd_mpu401_uart_input_trigger,
495 };
496 
497 static void snd_mpu401_uart_free(struct snd_rawmidi *rmidi)
498 {
499 	struct snd_mpu401 *mpu = rmidi->private_data;
500 	if (mpu->irq >= 0)
501 		free_irq(mpu->irq, (void *) mpu);
502 	release_and_free_resource(mpu->res);
503 	kfree(mpu);
504 }
505 
506 /**
507  * snd_mpu401_uart_new - create an MPU401-UART instance
508  * @card: the card instance
509  * @device: the device index, zero-based
510  * @hardware: the hardware type, MPU401_HW_XXXX
511  * @port: the base address of MPU401 port
512  * @info_flags: bitflags MPU401_INFO_XXX
513  * @irq: the ISA irq number, -1 if not to be allocated
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  * Return: 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,
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) {
547 		err = -ENOMEM;
548 		goto free_device;
549 	}
550 	rmidi->private_data = mpu;
551 	rmidi->private_free = snd_mpu401_uart_free;
552 	spin_lock_init(&mpu->input_lock);
553 	spin_lock_init(&mpu->output_lock);
554 	spin_lock_init(&mpu->timer_lock);
555 	mpu->hardware = hardware;
556 	mpu->irq = -1;
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) {
561 			snd_printk(KERN_ERR "mpu401_uart: "
562 				   "unable to grab port 0x%lx size %d\n",
563 				   port, res_size);
564 			err = -EBUSY;
565 			goto free_device;
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) {
581 		if (request_irq(irq, snd_mpu401_uart_interrupt, 0,
582 				"MPU401 UART", (void *) mpu)) {
583 			snd_printk(KERN_ERR "mpu401_uart: "
584 				   "unable to grab IRQ %d\n", irq);
585 			err = -EBUSY;
586 			goto free_device;
587 		}
588 	}
589 	if (irq < 0 && !(info_flags & MPU401_INFO_IRQ_HOOK))
590 		info_flags |= MPU401_INFO_USE_TIMER;
591 	mpu->info_flags = info_flags;
592 	mpu->irq = irq;
593 	if (card->shortname[0])
594 		snprintf(rmidi->name, sizeof(rmidi->name), "%s MIDI",
595 			 card->shortname);
596 	else
597 		sprintf(rmidi->name, "MPU-401 MIDI %d-%d",card->number, device);
598 	if (out_enable) {
599 		snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
600 				    &snd_mpu401_uart_output);
601 		rmidi->info_flags |= SNDRV_RAWMIDI_INFO_OUTPUT;
602 	}
603 	if (in_enable) {
604 		snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT,
605 				    &snd_mpu401_uart_input);
606 		rmidi->info_flags |= SNDRV_RAWMIDI_INFO_INPUT;
607 		if (out_enable)
608 			rmidi->info_flags |= SNDRV_RAWMIDI_INFO_DUPLEX;
609 	}
610 	mpu->rmidi = rmidi;
611 	if (rrawmidi)
612 		*rrawmidi = rmidi;
613 	return 0;
614 free_device:
615 	snd_device_free(card, rmidi);
616 	return err;
617 }
618 
619 EXPORT_SYMBOL(snd_mpu401_uart_new);
620 
621 /*
622  *  INIT part
623  */
624 
625 static int __init alsa_mpu401_uart_init(void)
626 {
627 	return 0;
628 }
629 
630 static void __exit alsa_mpu401_uart_exit(void)
631 {
632 }
633 
634 module_init(alsa_mpu401_uart_init)
635 module_exit(alsa_mpu401_uart_exit)
636