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)	(!(mpu->read(mpu, MPU401C(mpu)) & 0x80))
53 #define snd_mpu401_output_ready(mpu)	(!(mpu->read(mpu, MPU401C(mpu)) & 0x40))
54 
55 #define MPU401_RESET		0xff
56 #define MPU401_ENTER_UART	0x3f
57 #define MPU401_ACK		0xfe
58 
59 /* Build in lowlevel io */
60 static void mpu401_write_port(struct snd_mpu401 *mpu, unsigned char data,
61 			      unsigned long addr)
62 {
63 	outb(data, addr);
64 }
65 
66 static unsigned char mpu401_read_port(struct snd_mpu401 *mpu,
67 				      unsigned long addr)
68 {
69 	return inb(addr);
70 }
71 
72 static void mpu401_write_mmio(struct snd_mpu401 *mpu, unsigned char data,
73 			      unsigned long addr)
74 {
75 	writeb(data, (void __iomem *)addr);
76 }
77 
78 static unsigned char mpu401_read_mmio(struct snd_mpu401 *mpu,
79 				      unsigned long addr)
80 {
81 	return readb((void __iomem *)addr);
82 }
83 /*  */
84 
85 static void snd_mpu401_uart_clear_rx(struct snd_mpu401 *mpu)
86 {
87 	int timeout = 100000;
88 	for (; timeout > 0 && snd_mpu401_input_avail(mpu); timeout--)
89 		mpu->read(mpu, MPU401D(mpu));
90 #ifdef CONFIG_SND_DEBUG
91 	if (timeout <= 0)
92 		snd_printk(KERN_ERR "cmd: clear rx timeout (status = 0x%x)\n",
93 			   mpu->read(mpu, MPU401C(mpu)));
94 #endif
95 }
96 
97 static void uart_interrupt_tx(struct snd_mpu401 *mpu)
98 {
99 	unsigned long flags;
100 
101 	if (test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode) &&
102 	    test_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode)) {
103 		spin_lock_irqsave(&mpu->output_lock, flags);
104 		snd_mpu401_uart_output_write(mpu);
105 		spin_unlock_irqrestore(&mpu->output_lock, flags);
106 	}
107 }
108 
109 static void _snd_mpu401_uart_interrupt(struct snd_mpu401 *mpu)
110 {
111 	unsigned long flags;
112 
113 	if (mpu->info_flags & MPU401_INFO_INPUT) {
114 		spin_lock_irqsave(&mpu->input_lock, flags);
115 		if (test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
116 			snd_mpu401_uart_input_read(mpu);
117 		else
118 			snd_mpu401_uart_clear_rx(mpu);
119 		spin_unlock_irqrestore(&mpu->input_lock, flags);
120 	}
121 	if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
122 		/* ok. for better Tx performance try do some output
123 		   when input is done */
124 		uart_interrupt_tx(mpu);
125 }
126 
127 /**
128  * snd_mpu401_uart_interrupt - generic MPU401-UART interrupt handler
129  * @irq: the irq number
130  * @dev_id: mpu401 instance
131  *
132  * Processes the interrupt for MPU401-UART i/o.
133  */
134 irqreturn_t snd_mpu401_uart_interrupt(int irq, void *dev_id)
135 {
136 	struct snd_mpu401 *mpu = dev_id;
137 
138 	if (mpu == NULL)
139 		return IRQ_NONE;
140 	_snd_mpu401_uart_interrupt(mpu);
141 	return IRQ_HANDLED;
142 }
143 
144 EXPORT_SYMBOL(snd_mpu401_uart_interrupt);
145 
146 /**
147  * snd_mpu401_uart_interrupt_tx - generic MPU401-UART transmit irq handler
148  * @irq: the irq number
149  * @dev_id: mpu401 instance
150  *
151  * Processes the interrupt for MPU401-UART output.
152  */
153 irqreturn_t snd_mpu401_uart_interrupt_tx(int irq, void *dev_id)
154 {
155 	struct snd_mpu401 *mpu = dev_id;
156 
157 	if (mpu == NULL)
158 		return IRQ_NONE;
159 	uart_interrupt_tx(mpu);
160 	return IRQ_HANDLED;
161 }
162 
163 EXPORT_SYMBOL(snd_mpu401_uart_interrupt_tx);
164 
165 /*
166  * timer callback
167  * reprogram the timer and call the interrupt job
168  */
169 static void snd_mpu401_uart_timer(unsigned long data)
170 {
171 	struct snd_mpu401 *mpu = (struct snd_mpu401 *)data;
172 	unsigned long flags;
173 
174 	spin_lock_irqsave(&mpu->timer_lock, flags);
175 	/*mpu->mode |= MPU401_MODE_TIMER;*/
176 	mpu->timer.expires = 1 + jiffies;
177 	add_timer(&mpu->timer);
178 	spin_unlock_irqrestore(&mpu->timer_lock, flags);
179 	if (mpu->rmidi)
180 		_snd_mpu401_uart_interrupt(mpu);
181 }
182 
183 /*
184  * initialize the timer callback if not programmed yet
185  */
186 static void snd_mpu401_uart_add_timer (struct snd_mpu401 *mpu, int input)
187 {
188 	unsigned long flags;
189 
190 	spin_lock_irqsave (&mpu->timer_lock, flags);
191 	if (mpu->timer_invoked == 0) {
192 		init_timer(&mpu->timer);
193 		mpu->timer.data = (unsigned long)mpu;
194 		mpu->timer.function = snd_mpu401_uart_timer;
195 		mpu->timer.expires = 1 + jiffies;
196 		add_timer(&mpu->timer);
197 	}
198 	mpu->timer_invoked |= input ? MPU401_MODE_INPUT_TIMER :
199 		MPU401_MODE_OUTPUT_TIMER;
200 	spin_unlock_irqrestore (&mpu->timer_lock, flags);
201 }
202 
203 /*
204  * remove the timer callback if still active
205  */
206 static void snd_mpu401_uart_remove_timer (struct snd_mpu401 *mpu, int input)
207 {
208 	unsigned long flags;
209 
210 	spin_lock_irqsave (&mpu->timer_lock, flags);
211 	if (mpu->timer_invoked) {
212 		mpu->timer_invoked &= input ? ~MPU401_MODE_INPUT_TIMER :
213 			~MPU401_MODE_OUTPUT_TIMER;
214 		if (! mpu->timer_invoked)
215 			del_timer(&mpu->timer);
216 	}
217 	spin_unlock_irqrestore (&mpu->timer_lock, flags);
218 }
219 
220 /*
221  * send a UART command
222  * return zero if successful, non-zero for some errors
223  */
224 
225 static int snd_mpu401_uart_cmd(struct snd_mpu401 * mpu, unsigned char cmd,
226 			       int ack)
227 {
228 	unsigned long flags;
229 	int timeout, ok;
230 
231 	spin_lock_irqsave(&mpu->input_lock, flags);
232 	if (mpu->hardware != MPU401_HW_TRID4DWAVE) {
233 		mpu->write(mpu, 0x00, MPU401D(mpu));
234 		/*snd_mpu401_uart_clear_rx(mpu);*/
235 	}
236 	/* ok. standard MPU-401 initialization */
237 	if (mpu->hardware != MPU401_HW_SB) {
238 		for (timeout = 1000; timeout > 0 &&
239 			     !snd_mpu401_output_ready(mpu); timeout--)
240 			udelay(10);
241 #ifdef CONFIG_SND_DEBUG
242 		if (!timeout)
243 			snd_printk(KERN_ERR "cmd: tx timeout (status = 0x%x)\n",
244 				   mpu->read(mpu, MPU401C(mpu)));
245 #endif
246 	}
247 	mpu->write(mpu, cmd, MPU401C(mpu));
248 	if (ack) {
249 		ok = 0;
250 		timeout = 10000;
251 		while (!ok && timeout-- > 0) {
252 			if (snd_mpu401_input_avail(mpu)) {
253 				if (mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
254 					ok = 1;
255 			}
256 		}
257 		if (!ok && mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
258 			ok = 1;
259 	} else
260 		ok = 1;
261 	spin_unlock_irqrestore(&mpu->input_lock, flags);
262 	if (!ok) {
263 		snd_printk(KERN_ERR "cmd: 0x%x failed at 0x%lx "
264 			   "(status = 0x%x, data = 0x%x)\n", cmd, mpu->port,
265 			   mpu->read(mpu, MPU401C(mpu)),
266 			   mpu->read(mpu, MPU401D(mpu)));
267 		return 1;
268 	}
269 	return 0;
270 }
271 
272 static int snd_mpu401_do_reset(struct snd_mpu401 *mpu)
273 {
274 	if (snd_mpu401_uart_cmd(mpu, MPU401_RESET, 1))
275 		return -EIO;
276 	if (snd_mpu401_uart_cmd(mpu, MPU401_ENTER_UART, 0))
277 		return -EIO;
278 	return 0;
279 }
280 
281 /*
282  * input/output open/close - protected by open_mutex in rawmidi.c
283  */
284 static int snd_mpu401_uart_input_open(struct snd_rawmidi_substream *substream)
285 {
286 	struct snd_mpu401 *mpu;
287 	int err;
288 
289 	mpu = substream->rmidi->private_data;
290 	if (mpu->open_input && (err = mpu->open_input(mpu)) < 0)
291 		return err;
292 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode)) {
293 		if (snd_mpu401_do_reset(mpu) < 0)
294 			goto error_out;
295 	}
296 	mpu->substream_input = substream;
297 	set_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
298 	return 0;
299 
300 error_out:
301 	if (mpu->open_input && mpu->close_input)
302 		mpu->close_input(mpu);
303 	return -EIO;
304 }
305 
306 static int snd_mpu401_uart_output_open(struct snd_rawmidi_substream *substream)
307 {
308 	struct snd_mpu401 *mpu;
309 	int err;
310 
311 	mpu = substream->rmidi->private_data;
312 	if (mpu->open_output && (err = mpu->open_output(mpu)) < 0)
313 		return err;
314 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode)) {
315 		if (snd_mpu401_do_reset(mpu) < 0)
316 			goto error_out;
317 	}
318 	mpu->substream_output = substream;
319 	set_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
320 	return 0;
321 
322 error_out:
323 	if (mpu->open_output && mpu->close_output)
324 		mpu->close_output(mpu);
325 	return -EIO;
326 }
327 
328 static int snd_mpu401_uart_input_close(struct snd_rawmidi_substream *substream)
329 {
330 	struct snd_mpu401 *mpu;
331 	int err = 0;
332 
333 	mpu = substream->rmidi->private_data;
334 	clear_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
335 	mpu->substream_input = NULL;
336 	if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode))
337 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
338 	if (mpu->close_input)
339 		mpu->close_input(mpu);
340 	if (err)
341 		return -EIO;
342 	return 0;
343 }
344 
345 static int snd_mpu401_uart_output_close(struct snd_rawmidi_substream *substream)
346 {
347 	struct snd_mpu401 *mpu;
348 	int err = 0;
349 
350 	mpu = substream->rmidi->private_data;
351 	clear_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
352 	mpu->substream_output = NULL;
353 	if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
354 		err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
355 	if (mpu->close_output)
356 		mpu->close_output(mpu);
357 	if (err)
358 		return -EIO;
359 	return 0;
360 }
361 
362 /*
363  * trigger input callback
364  */
365 static void
366 snd_mpu401_uart_input_trigger(struct snd_rawmidi_substream *substream, int up)
367 {
368 	unsigned long flags;
369 	struct snd_mpu401 *mpu;
370 	int max = 64;
371 
372 	mpu = substream->rmidi->private_data;
373 	if (up) {
374 		if (! test_and_set_bit(MPU401_MODE_BIT_INPUT_TRIGGER,
375 				       &mpu->mode)) {
376 			/* first time - flush FIFO */
377 			while (max-- > 0)
378 				mpu->read(mpu, MPU401D(mpu));
379 			if (mpu->irq < 0)
380 				snd_mpu401_uart_add_timer(mpu, 1);
381 		}
382 
383 		/* read data in advance */
384 		spin_lock_irqsave(&mpu->input_lock, flags);
385 		snd_mpu401_uart_input_read(mpu);
386 		spin_unlock_irqrestore(&mpu->input_lock, flags);
387 	} else {
388 		if (mpu->irq < 0)
389 			snd_mpu401_uart_remove_timer(mpu, 1);
390 		clear_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode);
391 	}
392 
393 }
394 
395 /*
396  * transfer input pending data
397  * call with input_lock spinlock held
398  */
399 static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu)
400 {
401 	int max = 128;
402 	unsigned char byte;
403 
404 	while (max-- > 0) {
405 		if (! snd_mpu401_input_avail(mpu))
406 			break; /* input not available */
407 		byte = mpu->read(mpu, MPU401D(mpu));
408 		if (test_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode))
409 			snd_rawmidi_receive(mpu->substream_input, &byte, 1);
410 	}
411 }
412 
413 /*
414  *  Tx FIFO sizes:
415  *    CS4237B			- 16 bytes
416  *    AudioDrive ES1688         - 12 bytes
417  *    S3 SonicVibes             -  8 bytes
418  *    SoundBlaster AWE 64       -  2 bytes (ugly hardware)
419  */
420 
421 /*
422  * write output pending bytes
423  * call with output_lock spinlock held
424  */
425 static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu)
426 {
427 	unsigned char byte;
428 	int max = 256, timeout;
429 
430 	do {
431 		if (snd_rawmidi_transmit_peek(mpu->substream_output,
432 					      &byte, 1) == 1) {
433 			for (timeout = 100; timeout > 0; timeout--) {
434 				if (snd_mpu401_output_ready(mpu))
435 					break;
436 			}
437 			if (timeout == 0)
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 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 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_flags && 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 irq number, -1 if no interrupt for mpu
514  * @irq_flags: the irq request flags (SA_XXX), 0 if irq was already reserved.
515  * @rrawmidi: the pointer to store the new rawmidi instance
516  *
517  * Creates a new MPU-401 instance.
518  *
519  * Note that the rawmidi instance is returned on the rrawmidi argument,
520  * not the mpu401 instance itself.  To access to the mpu401 instance,
521  * cast from rawmidi->private_data (with struct snd_mpu401 magic-cast).
522  *
523  * Returns zero if successful, or a negative error code.
524  */
525 int snd_mpu401_uart_new(struct snd_card *card, int device,
526 			unsigned short hardware,
527 			unsigned long port,
528 			unsigned int info_flags,
529 			int irq, int irq_flags,
530 			struct snd_rawmidi ** rrawmidi)
531 {
532 	struct snd_mpu401 *mpu;
533 	struct snd_rawmidi *rmidi;
534 	int in_enable, out_enable;
535 	int err;
536 
537 	if (rrawmidi)
538 		*rrawmidi = NULL;
539 	if (! (info_flags & (MPU401_INFO_INPUT | MPU401_INFO_OUTPUT)))
540 		info_flags |= MPU401_INFO_INPUT | MPU401_INFO_OUTPUT;
541 	in_enable = (info_flags & MPU401_INFO_INPUT) ? 1 : 0;
542 	out_enable = (info_flags & MPU401_INFO_OUTPUT) ? 1 : 0;
543 	if ((err = snd_rawmidi_new(card, "MPU-401U", device,
544 				   out_enable, in_enable, &rmidi)) < 0)
545 		return err;
546 	mpu = kzalloc(sizeof(*mpu), GFP_KERNEL);
547 	if (mpu == NULL) {
548 		snd_printk(KERN_ERR "mpu401_uart: cannot allocate\n");
549 		snd_device_free(card, rmidi);
550 		return -ENOMEM;
551 	}
552 	rmidi->private_data = mpu;
553 	rmidi->private_free = snd_mpu401_uart_free;
554 	spin_lock_init(&mpu->input_lock);
555 	spin_lock_init(&mpu->output_lock);
556 	spin_lock_init(&mpu->timer_lock);
557 	mpu->hardware = hardware;
558 	if (! (info_flags & MPU401_INFO_INTEGRATED)) {
559 		int res_size = hardware == MPU401_HW_PC98II ? 4 : 2;
560 		mpu->res = request_region(port, res_size, "MPU401 UART");
561 		if (mpu->res == NULL) {
562 			snd_printk(KERN_ERR "mpu401_uart: "
563 				   "unable to grab port 0x%lx size %d\n",
564 				   port, res_size);
565 			snd_device_free(card, rmidi);
566 			return -EBUSY;
567 		}
568 	}
569 	if (info_flags & MPU401_INFO_MMIO) {
570 		mpu->write = mpu401_write_mmio;
571 		mpu->read = mpu401_read_mmio;
572 	} else {
573 		mpu->write = mpu401_write_port;
574 		mpu->read = mpu401_read_port;
575 	}
576 	mpu->port = port;
577 	if (hardware == MPU401_HW_PC98II)
578 		mpu->cport = port + 2;
579 	else
580 		mpu->cport = port + 1;
581 	if (irq >= 0 && irq_flags) {
582 		if (request_irq(irq, snd_mpu401_uart_interrupt, irq_flags,
583 				"MPU401 UART", (void *) mpu)) {
584 			snd_printk(KERN_ERR "mpu401_uart: "
585 				   "unable to grab IRQ %d\n", irq);
586 			snd_device_free(card, rmidi);
587 			return -EBUSY;
588 		}
589 	}
590 	mpu->info_flags = info_flags;
591 	mpu->irq = irq;
592 	mpu->irq_flags = irq_flags;
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 }
615 
616 EXPORT_SYMBOL(snd_mpu401_uart_new);
617 
618 /*
619  *  INIT part
620  */
621 
622 static int __init alsa_mpu401_uart_init(void)
623 {
624 	return 0;
625 }
626 
627 static void __exit alsa_mpu401_uart_exit(void)
628 {
629 }
630 
631 module_init(alsa_mpu401_uart_init)
632 module_exit(alsa_mpu401_uart_exit)
633