xref: /linux/sound/drivers/mpu401/mpu401_uart.c (revision 5e8d780d745c1619aba81fe7166c5a4b5cad2b84)
1 /*
2  *  Copyright (c) by Jaroslav Kysela <perex@suse.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 <sound/driver.h>
32 #include <asm/io.h>
33 #include <linux/delay.h>
34 #include <linux/init.h>
35 #include <linux/slab.h>
36 #include <linux/ioport.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@suse.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)	(!(mpu->read(mpu, MPU401C(mpu)) & 0x80))
54 #define snd_mpu401_output_ready(mpu)	(!(mpu->read(mpu, MPU401C(mpu)) & 0x40))
55 
56 #define MPU401_RESET		0xff
57 #define MPU401_ENTER_UART	0x3f
58 #define MPU401_ACK		0xfe
59 
60 /* Build in lowlevel io */
61 static void mpu401_write_port(struct snd_mpu401 *mpu, unsigned char data,
62 			      unsigned long addr)
63 {
64 	outb(data, addr);
65 }
66 
67 static unsigned char mpu401_read_port(struct snd_mpu401 *mpu,
68 				      unsigned long addr)
69 {
70 	return inb(addr);
71 }
72 
73 static void mpu401_write_mmio(struct snd_mpu401 *mpu, unsigned char data,
74 			      unsigned long addr)
75 {
76 	writeb(data, (void __iomem *)addr);
77 }
78 
79 static unsigned char mpu401_read_mmio(struct snd_mpu401 *mpu,
80 				      unsigned long addr)
81 {
82 	return readb((void __iomem *)addr);
83 }
84 /*  */
85 
86 static void snd_mpu401_uart_clear_rx(struct snd_mpu401 *mpu)
87 {
88 	int timeout = 100000;
89 	for (; timeout > 0 && snd_mpu401_input_avail(mpu); timeout--)
90 		mpu->read(mpu, MPU401D(mpu));
91 #ifdef CONFIG_SND_DEBUG
92 	if (timeout <= 0)
93 		snd_printk(KERN_ERR "cmd: clear rx timeout (status = 0x%x)\n",
94 			   mpu->read(mpu, MPU401C(mpu)));
95 #endif
96 }
97 
98 static void uart_interrupt_tx(struct snd_mpu401 *mpu)
99 {
100 	if (test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode) &&
101 	    test_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode)) {
102 		spin_lock(&mpu->output_lock);
103 		snd_mpu401_uart_output_write(mpu);
104 		spin_unlock(&mpu->output_lock);
105 	}
106 }
107 
108 static void _snd_mpu401_uart_interrupt(struct snd_mpu401 *mpu)
109 {
110 	if (mpu->info_flags & MPU401_INFO_INPUT) {
111 		spin_lock(&mpu->input_lock);
112 		if (test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
113 			snd_mpu401_uart_input_read(mpu);
114 		else
115 			snd_mpu401_uart_clear_rx(mpu);
116 		spin_unlock(&mpu->input_lock);
117 	}
118 	if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
119 		/* ok. for better Tx performance try do some output
120 		   when input is done */
121 		uart_interrupt_tx(mpu);
122 }
123 
124 /**
125  * snd_mpu401_uart_interrupt - generic MPU401-UART interrupt handler
126  * @irq: the irq number
127  * @dev_id: mpu401 instance
128  * @regs: the reigster
129  *
130  * Processes the interrupt for MPU401-UART i/o.
131  */
132 irqreturn_t snd_mpu401_uart_interrupt(int irq, void *dev_id,
133 				      struct pt_regs *regs)
134 {
135 	struct snd_mpu401 *mpu = dev_id;
136 
137 	if (mpu == NULL)
138 		return IRQ_NONE;
139 	_snd_mpu401_uart_interrupt(mpu);
140 	return IRQ_HANDLED;
141 }
142 
143 EXPORT_SYMBOL(snd_mpu401_uart_interrupt);
144 
145 /**
146  * snd_mpu401_uart_interrupt_tx - generic MPU401-UART transmit irq handler
147  * @irq: the irq number
148  * @dev_id: mpu401 instance
149  * @regs: the reigster
150  *
151  * Processes the interrupt for MPU401-UART output.
152  */
153 irqreturn_t snd_mpu401_uart_interrupt_tx(int irq, void *dev_id,
154 					 struct pt_regs *regs)
155 {
156 	struct snd_mpu401 *mpu = dev_id;
157 
158 	if (mpu == NULL)
159 		return IRQ_NONE;
160 	uart_interrupt_tx(mpu);
161 	return IRQ_HANDLED;
162 }
163 
164 EXPORT_SYMBOL(snd_mpu401_uart_interrupt_tx);
165 
166 /*
167  * timer callback
168  * reprogram the timer and call the interrupt job
169  */
170 static void snd_mpu401_uart_timer(unsigned long data)
171 {
172 	struct snd_mpu401 *mpu = (struct snd_mpu401 *)data;
173 	unsigned long flags;
174 
175 	spin_lock_irqsave(&mpu->timer_lock, flags);
176 	/*mpu->mode |= MPU401_MODE_TIMER;*/
177 	mpu->timer.expires = 1 + jiffies;
178 	add_timer(&mpu->timer);
179 	spin_unlock_irqrestore(&mpu->timer_lock, flags);
180 	if (mpu->rmidi)
181 		_snd_mpu401_uart_interrupt(mpu);
182 }
183 
184 /*
185  * initialize the timer callback if not programmed yet
186  */
187 static void snd_mpu401_uart_add_timer (struct snd_mpu401 *mpu, int input)
188 {
189 	unsigned long flags;
190 
191 	spin_lock_irqsave (&mpu->timer_lock, flags);
192 	if (mpu->timer_invoked == 0) {
193 		init_timer(&mpu->timer);
194 		mpu->timer.data = (unsigned long)mpu;
195 		mpu->timer.function = snd_mpu401_uart_timer;
196 		mpu->timer.expires = 1 + jiffies;
197 		add_timer(&mpu->timer);
198 	}
199 	mpu->timer_invoked |= input ? MPU401_MODE_INPUT_TIMER :
200 		MPU401_MODE_OUTPUT_TIMER;
201 	spin_unlock_irqrestore (&mpu->timer_lock, flags);
202 }
203 
204 /*
205  * remove the timer callback if still active
206  */
207 static void snd_mpu401_uart_remove_timer (struct snd_mpu401 *mpu, int input)
208 {
209 	unsigned long flags;
210 
211 	spin_lock_irqsave (&mpu->timer_lock, flags);
212 	if (mpu->timer_invoked) {
213 		mpu->timer_invoked &= input ? ~MPU401_MODE_INPUT_TIMER :
214 			~MPU401_MODE_OUTPUT_TIMER;
215 		if (! mpu->timer_invoked)
216 			del_timer(&mpu->timer);
217 	}
218 	spin_unlock_irqrestore (&mpu->timer_lock, flags);
219 }
220 
221 /*
222  * send a UART command
223  * return zero if successful, non-zero for some errors
224  */
225 
226 static int snd_mpu401_uart_cmd(struct snd_mpu401 * mpu, unsigned char cmd,
227 			       int ack)
228 {
229 	unsigned long flags;
230 	int timeout, ok;
231 
232 	spin_lock_irqsave(&mpu->input_lock, flags);
233 	if (mpu->hardware != MPU401_HW_TRID4DWAVE) {
234 		mpu->write(mpu, 0x00, MPU401D(mpu));
235 		/*snd_mpu401_uart_clear_rx(mpu);*/
236 	}
237 	/* ok. standard MPU-401 initialization */
238 	if (mpu->hardware != MPU401_HW_SB) {
239 		for (timeout = 1000; timeout > 0 &&
240 			     !snd_mpu401_output_ready(mpu); timeout--)
241 			udelay(10);
242 #ifdef CONFIG_SND_DEBUG
243 		if (!timeout)
244 			snd_printk(KERN_ERR "cmd: tx timeout (status = 0x%x)\n",
245 				   mpu->read(mpu, MPU401C(mpu)));
246 #endif
247 	}
248 	mpu->write(mpu, cmd, MPU401C(mpu));
249 	if (ack) {
250 		ok = 0;
251 		timeout = 10000;
252 		while (!ok && timeout-- > 0) {
253 			if (snd_mpu401_input_avail(mpu)) {
254 				if (mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
255 					ok = 1;
256 			}
257 		}
258 		if (!ok && mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
259 			ok = 1;
260 	} else
261 		ok = 1;
262 	spin_unlock_irqrestore(&mpu->input_lock, flags);
263 	if (!ok) {
264 		snd_printk(KERN_ERR "cmd: 0x%x failed at 0x%lx "
265 			   "(status = 0x%x, data = 0x%x)\n", cmd, mpu->port,
266 			   mpu->read(mpu, MPU401C(mpu)),
267 			   mpu->read(mpu, MPU401D(mpu)));
268 		return 1;
269 	}
270 	return 0;
271 }
272 
273 /*
274  * input/output open/close - protected by open_mutex in rawmidi.c
275  */
276 static int snd_mpu401_uart_input_open(struct snd_rawmidi_substream *substream)
277 {
278 	struct snd_mpu401 *mpu;
279 	int err;
280 
281 	mpu = substream->rmidi->private_data;
282 	if (mpu->open_input && (err = mpu->open_input(mpu)) < 0)
283 		return err;
284 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode)) {
285 		if (snd_mpu401_uart_cmd(mpu, MPU401_RESET, 1))
286 			goto error_out;
287 		if (snd_mpu401_uart_cmd(mpu, MPU401_ENTER_UART, 1))
288 			goto error_out;
289 	}
290 	mpu->substream_input = substream;
291 	set_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
292 	return 0;
293 
294 error_out:
295 	if (mpu->open_input && mpu->close_input)
296 		mpu->close_input(mpu);
297 	return -EIO;
298 }
299 
300 static int snd_mpu401_uart_output_open(struct snd_rawmidi_substream *substream)
301 {
302 	struct snd_mpu401 *mpu;
303 	int err;
304 
305 	mpu = substream->rmidi->private_data;
306 	if (mpu->open_output && (err = mpu->open_output(mpu)) < 0)
307 		return err;
308 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode)) {
309 		if (snd_mpu401_uart_cmd(mpu, MPU401_RESET, 1))
310 			goto error_out;
311 		if (snd_mpu401_uart_cmd(mpu, MPU401_ENTER_UART, 1))
312 			goto error_out;
313 	}
314 	mpu->substream_output = substream;
315 	set_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
316 	return 0;
317 
318 error_out:
319 	if (mpu->open_output && mpu->close_output)
320 		mpu->close_output(mpu);
321 	return -EIO;
322 }
323 
324 static int snd_mpu401_uart_input_close(struct snd_rawmidi_substream *substream)
325 {
326 	struct snd_mpu401 *mpu;
327 	int err = 0;
328 
329 	mpu = substream->rmidi->private_data;
330 	clear_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
331 	mpu->substream_input = NULL;
332 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode))
333 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
334 	if (mpu->close_input)
335 		mpu->close_input(mpu);
336 	if (err)
337 		return -EIO;
338 	return 0;
339 }
340 
341 static int snd_mpu401_uart_output_close(struct snd_rawmidi_substream *substream)
342 {
343 	struct snd_mpu401 *mpu;
344 	int err = 0;
345 
346 	mpu = substream->rmidi->private_data;
347 	clear_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
348 	mpu->substream_output = NULL;
349 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
350 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
351 	if (mpu->close_output)
352 		mpu->close_output(mpu);
353 	if (err)
354 		return -EIO;
355 	return 0;
356 }
357 
358 /*
359  * trigger input callback
360  */
361 static void
362 snd_mpu401_uart_input_trigger(struct snd_rawmidi_substream *substream, int up)
363 {
364 	unsigned long flags;
365 	struct snd_mpu401 *mpu;
366 	int max = 64;
367 
368 	mpu = substream->rmidi->private_data;
369 	if (up) {
370 		if (! test_and_set_bit(MPU401_MODE_BIT_INPUT_TRIGGER,
371 				       &mpu->mode)) {
372 			/* first time - flush FIFO */
373 			while (max-- > 0)
374 				mpu->read(mpu, MPU401D(mpu));
375 			if (mpu->irq < 0)
376 				snd_mpu401_uart_add_timer(mpu, 1);
377 		}
378 
379 		/* read data in advance */
380 		spin_lock_irqsave(&mpu->input_lock, flags);
381 		snd_mpu401_uart_input_read(mpu);
382 		spin_unlock_irqrestore(&mpu->input_lock, flags);
383 	} else {
384 		if (mpu->irq < 0)
385 			snd_mpu401_uart_remove_timer(mpu, 1);
386 		clear_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode);
387 	}
388 
389 }
390 
391 /*
392  * transfer input pending data
393  * call with input_lock spinlock held
394  */
395 static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu)
396 {
397 	int max = 128;
398 	unsigned char byte;
399 
400 	while (max-- > 0) {
401 		if (! snd_mpu401_input_avail(mpu))
402 			break; /* input not available */
403 		byte = mpu->read(mpu, MPU401D(mpu));
404 		if (test_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode))
405 			snd_rawmidi_receive(mpu->substream_input, &byte, 1);
406 	}
407 }
408 
409 /*
410  *  Tx FIFO sizes:
411  *    CS4237B			- 16 bytes
412  *    AudioDrive ES1688         - 12 bytes
413  *    S3 SonicVibes             -  8 bytes
414  *    SoundBlaster AWE 64       -  2 bytes (ugly hardware)
415  */
416 
417 /*
418  * write output pending bytes
419  * call with output_lock spinlock held
420  */
421 static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu)
422 {
423 	unsigned char byte;
424 	int max = 256, timeout;
425 
426 	do {
427 		if (snd_rawmidi_transmit_peek(mpu->substream_output,
428 					      &byte, 1) == 1) {
429 			for (timeout = 100; timeout > 0; timeout--) {
430 				if (snd_mpu401_output_ready(mpu))
431 					break;
432 			}
433 			if (timeout == 0)
434 				break;	/* Tx FIFO full - try again later */
435 			mpu->write(mpu, byte, MPU401D(mpu));
436 			snd_rawmidi_transmit_ack(mpu->substream_output, 1);
437 		} else {
438 			snd_mpu401_uart_remove_timer (mpu, 0);
439 			break;	/* no other data - leave the tx loop */
440 		}
441 	} while (--max > 0);
442 }
443 
444 /*
445  * output trigger callback
446  */
447 static void
448 snd_mpu401_uart_output_trigger(struct snd_rawmidi_substream *substream, int up)
449 {
450 	unsigned long flags;
451 	struct snd_mpu401 *mpu;
452 
453 	mpu = substream->rmidi->private_data;
454 	if (up) {
455 		set_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);
456 
457 		/* try to add the timer at each output trigger,
458 		 * since the output timer might have been removed in
459 		 * snd_mpu401_uart_output_write().
460 		 */
461 		if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
462 			snd_mpu401_uart_add_timer(mpu, 0);
463 
464 		/* output pending data */
465 		spin_lock_irqsave(&mpu->output_lock, flags);
466 		snd_mpu401_uart_output_write(mpu);
467 		spin_unlock_irqrestore(&mpu->output_lock, flags);
468 	} else {
469 		if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
470 			snd_mpu401_uart_remove_timer(mpu, 0);
471 		clear_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);
472 	}
473 }
474 
475 /*
476 
477  */
478 
479 static struct snd_rawmidi_ops snd_mpu401_uart_output =
480 {
481 	.open =		snd_mpu401_uart_output_open,
482 	.close =	snd_mpu401_uart_output_close,
483 	.trigger =	snd_mpu401_uart_output_trigger,
484 };
485 
486 static struct snd_rawmidi_ops snd_mpu401_uart_input =
487 {
488 	.open =		snd_mpu401_uart_input_open,
489 	.close =	snd_mpu401_uart_input_close,
490 	.trigger =	snd_mpu401_uart_input_trigger,
491 };
492 
493 static void snd_mpu401_uart_free(struct snd_rawmidi *rmidi)
494 {
495 	struct snd_mpu401 *mpu = rmidi->private_data;
496 	if (mpu->irq_flags && mpu->irq >= 0)
497 		free_irq(mpu->irq, (void *) mpu);
498 	release_and_free_resource(mpu->res);
499 	kfree(mpu);
500 }
501 
502 /**
503  * snd_mpu401_uart_new - create an MPU401-UART instance
504  * @card: the card instance
505  * @device: the device index, zero-based
506  * @hardware: the hardware type, MPU401_HW_XXXX
507  * @port: the base address of MPU401 port
508  * @info_flags: bitflags MPU401_INFO_XXX
509  * @irq: the irq number, -1 if no interrupt for mpu
510  * @irq_flags: the irq request flags (SA_XXX), 0 if irq was already reserved.
511  * @rrawmidi: the pointer to store the new rawmidi instance
512  *
513  * Creates a new MPU-401 instance.
514  *
515  * Note that the rawmidi instance is returned on the rrawmidi argument,
516  * not the mpu401 instance itself.  To access to the mpu401 instance,
517  * cast from rawmidi->private_data (with struct snd_mpu401 magic-cast).
518  *
519  * Returns zero if successful, or a negative error code.
520  */
521 int snd_mpu401_uart_new(struct snd_card *card, int device,
522 			unsigned short hardware,
523 			unsigned long port,
524 			unsigned int info_flags,
525 			int irq, int irq_flags,
526 			struct snd_rawmidi ** rrawmidi)
527 {
528 	struct snd_mpu401 *mpu;
529 	struct snd_rawmidi *rmidi;
530 	int in_enable, out_enable;
531 	int err;
532 
533 	if (rrawmidi)
534 		*rrawmidi = NULL;
535 	if (! (info_flags & (MPU401_INFO_INPUT | MPU401_INFO_OUTPUT)))
536 		info_flags |= MPU401_INFO_INPUT | MPU401_INFO_OUTPUT;
537 	in_enable = (info_flags & MPU401_INFO_INPUT) ? 1 : 0;
538 	out_enable = (info_flags & MPU401_INFO_OUTPUT) ? 1 : 0;
539 	if ((err = snd_rawmidi_new(card, "MPU-401U", device,
540 				   out_enable, in_enable, &rmidi)) < 0)
541 		return err;
542 	mpu = kzalloc(sizeof(*mpu), GFP_KERNEL);
543 	if (mpu == NULL) {
544 		snd_printk(KERN_ERR "mpu401_uart: cannot allocate\n");
545 		snd_device_free(card, rmidi);
546 		return -ENOMEM;
547 	}
548 	rmidi->private_data = mpu;
549 	rmidi->private_free = snd_mpu401_uart_free;
550 	spin_lock_init(&mpu->input_lock);
551 	spin_lock_init(&mpu->output_lock);
552 	spin_lock_init(&mpu->timer_lock);
553 	mpu->hardware = hardware;
554 	if (! (info_flags & MPU401_INFO_INTEGRATED)) {
555 		int res_size = hardware == MPU401_HW_PC98II ? 4 : 2;
556 		mpu->res = request_region(port, res_size, "MPU401 UART");
557 		if (mpu->res == NULL) {
558 			snd_printk(KERN_ERR "mpu401_uart: "
559 				   "unable to grab port 0x%lx size %d\n",
560 				   port, res_size);
561 			snd_device_free(card, rmidi);
562 			return -EBUSY;
563 		}
564 	}
565 	if (info_flags & MPU401_INFO_MMIO) {
566 		mpu->write = mpu401_write_mmio;
567 		mpu->read = mpu401_read_mmio;
568 	} else {
569 		mpu->write = mpu401_write_port;
570 		mpu->read = mpu401_read_port;
571 	}
572 	mpu->port = port;
573 	if (hardware == MPU401_HW_PC98II)
574 		mpu->cport = port + 2;
575 	else
576 		mpu->cport = port + 1;
577 	if (irq >= 0 && irq_flags) {
578 		if (request_irq(irq, snd_mpu401_uart_interrupt, irq_flags,
579 				"MPU401 UART", (void *) mpu)) {
580 			snd_printk(KERN_ERR "mpu401_uart: "
581 				   "unable to grab IRQ %d\n", irq);
582 			snd_device_free(card, rmidi);
583 			return -EBUSY;
584 		}
585 	}
586 	mpu->info_flags = info_flags;
587 	mpu->irq = irq;
588 	mpu->irq_flags = irq_flags;
589 	if (card->shortname[0])
590 		snprintf(rmidi->name, sizeof(rmidi->name), "%s MIDI",
591 			 card->shortname);
592 	else
593 		sprintf(rmidi->name, "MPU-401 MIDI %d-%d",card->number, device);
594 	if (out_enable) {
595 		snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
596 				    &snd_mpu401_uart_output);
597 		rmidi->info_flags |= SNDRV_RAWMIDI_INFO_OUTPUT;
598 	}
599 	if (in_enable) {
600 		snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT,
601 				    &snd_mpu401_uart_input);
602 		rmidi->info_flags |= SNDRV_RAWMIDI_INFO_INPUT;
603 		if (out_enable)
604 			rmidi->info_flags |= SNDRV_RAWMIDI_INFO_DUPLEX;
605 	}
606 	mpu->rmidi = rmidi;
607 	if (rrawmidi)
608 		*rrawmidi = rmidi;
609 	return 0;
610 }
611 
612 EXPORT_SYMBOL(snd_mpu401_uart_new);
613 
614 /*
615  *  INIT part
616  */
617 
618 static int __init alsa_mpu401_uart_init(void)
619 {
620 	return 0;
621 }
622 
623 static void __exit alsa_mpu401_uart_exit(void)
624 {
625 }
626 
627 module_init(alsa_mpu401_uart_init)
628 module_exit(alsa_mpu401_uart_exit)
629