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 <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@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)	(!(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 	unsigned long flags;
101 
102 	if (test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode) &&
103 	    test_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode)) {
104 		spin_lock_irqsave(&mpu->output_lock, flags);
105 		snd_mpu401_uart_output_write(mpu);
106 		spin_unlock_irqrestore(&mpu->output_lock, flags);
107 	}
108 }
109 
110 static void _snd_mpu401_uart_interrupt(struct snd_mpu401 *mpu)
111 {
112 	unsigned long flags;
113 
114 	if (mpu->info_flags & MPU401_INFO_INPUT) {
115 		spin_lock_irqsave(&mpu->input_lock, flags);
116 		if (test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
117 			snd_mpu401_uart_input_read(mpu);
118 		else
119 			snd_mpu401_uart_clear_rx(mpu);
120 		spin_unlock_irqrestore(&mpu->input_lock, flags);
121 	}
122 	if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
123 		/* ok. for better Tx performance try do some output
124 		   when input is done */
125 		uart_interrupt_tx(mpu);
126 }
127 
128 /**
129  * snd_mpu401_uart_interrupt - generic MPU401-UART interrupt handler
130  * @irq: the irq number
131  * @dev_id: mpu401 instance
132  *
133  * Processes the interrupt for MPU401-UART i/o.
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 == NULL)
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 irqreturn_t snd_mpu401_uart_interrupt_tx(int irq, void *dev_id)
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 static int snd_mpu401_do_reset(struct snd_mpu401 *mpu)
274 {
275 	if (snd_mpu401_uart_cmd(mpu, MPU401_RESET, 1))
276 		return -EIO;
277 	if (snd_mpu401_uart_cmd(mpu, MPU401_ENTER_UART, 0))
278 		return -EIO;
279 	return 0;
280 }
281 
282 /*
283  * input/output open/close - protected by open_mutex in rawmidi.c
284  */
285 static int snd_mpu401_uart_input_open(struct snd_rawmidi_substream *substream)
286 {
287 	struct snd_mpu401 *mpu;
288 	int err;
289 
290 	mpu = substream->rmidi->private_data;
291 	if (mpu->open_input && (err = mpu->open_input(mpu)) < 0)
292 		return err;
293 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode)) {
294 		if (snd_mpu401_do_reset(mpu) < 0)
295 			goto error_out;
296 	}
297 	mpu->substream_input = substream;
298 	set_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
299 	return 0;
300 
301 error_out:
302 	if (mpu->open_input && mpu->close_input)
303 		mpu->close_input(mpu);
304 	return -EIO;
305 }
306 
307 static int snd_mpu401_uart_output_open(struct snd_rawmidi_substream *substream)
308 {
309 	struct snd_mpu401 *mpu;
310 	int err;
311 
312 	mpu = substream->rmidi->private_data;
313 	if (mpu->open_output && (err = mpu->open_output(mpu)) < 0)
314 		return err;
315 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode)) {
316 		if (snd_mpu401_do_reset(mpu) < 0)
317 			goto error_out;
318 	}
319 	mpu->substream_output = substream;
320 	set_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
321 	return 0;
322 
323 error_out:
324 	if (mpu->open_output && mpu->close_output)
325 		mpu->close_output(mpu);
326 	return -EIO;
327 }
328 
329 static int snd_mpu401_uart_input_close(struct snd_rawmidi_substream *substream)
330 {
331 	struct snd_mpu401 *mpu;
332 	int err = 0;
333 
334 	mpu = substream->rmidi->private_data;
335 	clear_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
336 	mpu->substream_input = NULL;
337 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode))
338 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
339 	if (mpu->close_input)
340 		mpu->close_input(mpu);
341 	if (err)
342 		return -EIO;
343 	return 0;
344 }
345 
346 static int snd_mpu401_uart_output_close(struct snd_rawmidi_substream *substream)
347 {
348 	struct snd_mpu401 *mpu;
349 	int err = 0;
350 
351 	mpu = substream->rmidi->private_data;
352 	clear_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
353 	mpu->substream_output = NULL;
354 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
355 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
356 	if (mpu->close_output)
357 		mpu->close_output(mpu);
358 	if (err)
359 		return -EIO;
360 	return 0;
361 }
362 
363 /*
364  * trigger input callback
365  */
366 static void
367 snd_mpu401_uart_input_trigger(struct snd_rawmidi_substream *substream, int up)
368 {
369 	unsigned long flags;
370 	struct snd_mpu401 *mpu;
371 	int max = 64;
372 
373 	mpu = substream->rmidi->private_data;
374 	if (up) {
375 		if (! test_and_set_bit(MPU401_MODE_BIT_INPUT_TRIGGER,
376 				       &mpu->mode)) {
377 			/* first time - flush FIFO */
378 			while (max-- > 0)
379 				mpu->read(mpu, MPU401D(mpu));
380 			if (mpu->irq < 0)
381 				snd_mpu401_uart_add_timer(mpu, 1);
382 		}
383 
384 		/* read data in advance */
385 		spin_lock_irqsave(&mpu->input_lock, flags);
386 		snd_mpu401_uart_input_read(mpu);
387 		spin_unlock_irqrestore(&mpu->input_lock, flags);
388 	} else {
389 		if (mpu->irq < 0)
390 			snd_mpu401_uart_remove_timer(mpu, 1);
391 		clear_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode);
392 	}
393 
394 }
395 
396 /*
397  * transfer input pending data
398  * call with input_lock spinlock held
399  */
400 static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu)
401 {
402 	int max = 128;
403 	unsigned char byte;
404 
405 	while (max-- > 0) {
406 		if (! snd_mpu401_input_avail(mpu))
407 			break; /* input not available */
408 		byte = mpu->read(mpu, MPU401D(mpu));
409 		if (test_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode))
410 			snd_rawmidi_receive(mpu->substream_input, &byte, 1);
411 	}
412 }
413 
414 /*
415  *  Tx FIFO sizes:
416  *    CS4237B			- 16 bytes
417  *    AudioDrive ES1688         - 12 bytes
418  *    S3 SonicVibes             -  8 bytes
419  *    SoundBlaster AWE 64       -  2 bytes (ugly hardware)
420  */
421 
422 /*
423  * write output pending bytes
424  * call with output_lock spinlock held
425  */
426 static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu)
427 {
428 	unsigned char byte;
429 	int max = 256, timeout;
430 
431 	do {
432 		if (snd_rawmidi_transmit_peek(mpu->substream_output,
433 					      &byte, 1) == 1) {
434 			for (timeout = 100; timeout > 0; timeout--) {
435 				if (snd_mpu401_output_ready(mpu))
436 					break;
437 			}
438 			if (timeout == 0)
439 				break;	/* Tx FIFO full - try again later */
440 			mpu->write(mpu, byte, MPU401D(mpu));
441 			snd_rawmidi_transmit_ack(mpu->substream_output, 1);
442 		} else {
443 			snd_mpu401_uart_remove_timer (mpu, 0);
444 			break;	/* no other data - leave the tx loop */
445 		}
446 	} while (--max > 0);
447 }
448 
449 /*
450  * output trigger callback
451  */
452 static void
453 snd_mpu401_uart_output_trigger(struct snd_rawmidi_substream *substream, int up)
454 {
455 	unsigned long flags;
456 	struct snd_mpu401 *mpu;
457 
458 	mpu = substream->rmidi->private_data;
459 	if (up) {
460 		set_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);
461 
462 		/* try to add the timer at each output trigger,
463 		 * since the output timer might have been removed in
464 		 * snd_mpu401_uart_output_write().
465 		 */
466 		if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
467 			snd_mpu401_uart_add_timer(mpu, 0);
468 
469 		/* output pending data */
470 		spin_lock_irqsave(&mpu->output_lock, flags);
471 		snd_mpu401_uart_output_write(mpu);
472 		spin_unlock_irqrestore(&mpu->output_lock, flags);
473 	} else {
474 		if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
475 			snd_mpu401_uart_remove_timer(mpu, 0);
476 		clear_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);
477 	}
478 }
479 
480 /*
481 
482  */
483 
484 static struct snd_rawmidi_ops snd_mpu401_uart_output =
485 {
486 	.open =		snd_mpu401_uart_output_open,
487 	.close =	snd_mpu401_uart_output_close,
488 	.trigger =	snd_mpu401_uart_output_trigger,
489 };
490 
491 static struct snd_rawmidi_ops snd_mpu401_uart_input =
492 {
493 	.open =		snd_mpu401_uart_input_open,
494 	.close =	snd_mpu401_uart_input_close,
495 	.trigger =	snd_mpu401_uart_input_trigger,
496 };
497 
498 static void snd_mpu401_uart_free(struct snd_rawmidi *rmidi)
499 {
500 	struct snd_mpu401 *mpu = rmidi->private_data;
501 	if (mpu->irq_flags && mpu->irq >= 0)
502 		free_irq(mpu->irq, (void *) mpu);
503 	release_and_free_resource(mpu->res);
504 	kfree(mpu);
505 }
506 
507 /**
508  * snd_mpu401_uart_new - create an MPU401-UART instance
509  * @card: the card instance
510  * @device: the device index, zero-based
511  * @hardware: the hardware type, MPU401_HW_XXXX
512  * @port: the base address of MPU401 port
513  * @info_flags: bitflags MPU401_INFO_XXX
514  * @irq: the irq number, -1 if no interrupt for mpu
515  * @irq_flags: the irq request flags (SA_XXX), 0 if irq was already reserved.
516  * @rrawmidi: the pointer to store the new rawmidi instance
517  *
518  * Creates a new MPU-401 instance.
519  *
520  * Note that the rawmidi instance is returned on the rrawmidi argument,
521  * not the mpu401 instance itself.  To access to the mpu401 instance,
522  * cast from rawmidi->private_data (with struct snd_mpu401 magic-cast).
523  *
524  * Returns zero if successful, or a negative error code.
525  */
526 int snd_mpu401_uart_new(struct snd_card *card, int device,
527 			unsigned short hardware,
528 			unsigned long port,
529 			unsigned int info_flags,
530 			int irq, int irq_flags,
531 			struct snd_rawmidi ** rrawmidi)
532 {
533 	struct snd_mpu401 *mpu;
534 	struct snd_rawmidi *rmidi;
535 	int in_enable, out_enable;
536 	int err;
537 
538 	if (rrawmidi)
539 		*rrawmidi = NULL;
540 	if (! (info_flags & (MPU401_INFO_INPUT | MPU401_INFO_OUTPUT)))
541 		info_flags |= MPU401_INFO_INPUT | MPU401_INFO_OUTPUT;
542 	in_enable = (info_flags & MPU401_INFO_INPUT) ? 1 : 0;
543 	out_enable = (info_flags & MPU401_INFO_OUTPUT) ? 1 : 0;
544 	if ((err = snd_rawmidi_new(card, "MPU-401U", device,
545 				   out_enable, in_enable, &rmidi)) < 0)
546 		return err;
547 	mpu = kzalloc(sizeof(*mpu), GFP_KERNEL);
548 	if (mpu == NULL) {
549 		snd_printk(KERN_ERR "mpu401_uart: cannot allocate\n");
550 		snd_device_free(card, rmidi);
551 		return -ENOMEM;
552 	}
553 	rmidi->private_data = mpu;
554 	rmidi->private_free = snd_mpu401_uart_free;
555 	spin_lock_init(&mpu->input_lock);
556 	spin_lock_init(&mpu->output_lock);
557 	spin_lock_init(&mpu->timer_lock);
558 	mpu->hardware = hardware;
559 	if (! (info_flags & MPU401_INFO_INTEGRATED)) {
560 		int res_size = hardware == MPU401_HW_PC98II ? 4 : 2;
561 		mpu->res = request_region(port, res_size, "MPU401 UART");
562 		if (mpu->res == NULL) {
563 			snd_printk(KERN_ERR "mpu401_uart: "
564 				   "unable to grab port 0x%lx size %d\n",
565 				   port, res_size);
566 			snd_device_free(card, rmidi);
567 			return -EBUSY;
568 		}
569 	}
570 	if (info_flags & MPU401_INFO_MMIO) {
571 		mpu->write = mpu401_write_mmio;
572 		mpu->read = mpu401_read_mmio;
573 	} else {
574 		mpu->write = mpu401_write_port;
575 		mpu->read = mpu401_read_port;
576 	}
577 	mpu->port = port;
578 	if (hardware == MPU401_HW_PC98II)
579 		mpu->cport = port + 2;
580 	else
581 		mpu->cport = port + 1;
582 	if (irq >= 0 && irq_flags) {
583 		if (request_irq(irq, snd_mpu401_uart_interrupt, irq_flags,
584 				"MPU401 UART", (void *) mpu)) {
585 			snd_printk(KERN_ERR "mpu401_uart: "
586 				   "unable to grab IRQ %d\n", irq);
587 			snd_device_free(card, rmidi);
588 			return -EBUSY;
589 		}
590 	}
591 	mpu->info_flags = info_flags;
592 	mpu->irq = irq;
593 	mpu->irq_flags = irq_flags;
594 	if (card->shortname[0])
595 		snprintf(rmidi->name, sizeof(rmidi->name), "%s MIDI",
596 			 card->shortname);
597 	else
598 		sprintf(rmidi->name, "MPU-401 MIDI %d-%d",card->number, device);
599 	if (out_enable) {
600 		snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
601 				    &snd_mpu401_uart_output);
602 		rmidi->info_flags |= SNDRV_RAWMIDI_INFO_OUTPUT;
603 	}
604 	if (in_enable) {
605 		snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT,
606 				    &snd_mpu401_uart_input);
607 		rmidi->info_flags |= SNDRV_RAWMIDI_INFO_INPUT;
608 		if (out_enable)
609 			rmidi->info_flags |= SNDRV_RAWMIDI_INFO_DUPLEX;
610 	}
611 	mpu->rmidi = rmidi;
612 	if (rrawmidi)
613 		*rrawmidi = rmidi;
614 	return 0;
615 }
616 
617 EXPORT_SYMBOL(snd_mpu401_uart_new);
618 
619 /*
620  *  INIT part
621  */
622 
623 static int __init alsa_mpu401_uart_init(void)
624 {
625 	return 0;
626 }
627 
628 static void __exit alsa_mpu401_uart_exit(void)
629 {
630 }
631 
632 module_init(alsa_mpu401_uart_init)
633 module_exit(alsa_mpu401_uart_exit)
634