xref: /linux/sound/drivers/serial-u16550.c (revision f7af616c632ee2ac3af0876fe33bf9e0232e665a)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *   serial.c
4  *   Copyright (c) by Jaroslav Kysela <perex@perex.cz>,
5  *                    Isaku Yamahata <yamahata@private.email.ne.jp>,
6  *		      George Hansper <ghansper@apana.org.au>,
7  *		      Hannu Savolainen
8  *
9  *   This code is based on the code from ALSA 0.5.9, but heavily rewritten.
10  *
11  * Sat Mar 31 17:27:57 PST 2001 tim.mann@compaq.com
12  *      Added support for the Midiator MS-124T and for the MS-124W in
13  *      Single Addressed (S/A) or Multiple Burst (M/B) mode, with
14  *      power derived either parasitically from the serial port or
15  *      from a separate power supply.
16  *
17  *      More documentation can be found in serial-u16550.txt.
18  */
19 
20 #include <linux/init.h>
21 #include <linux/interrupt.h>
22 #include <linux/err.h>
23 #include <linux/platform_device.h>
24 #include <linux/slab.h>
25 #include <linux/ioport.h>
26 #include <linux/module.h>
27 #include <linux/io.h>
28 #include <sound/core.h>
29 #include <sound/rawmidi.h>
30 #include <sound/initval.h>
31 
32 #include <linux/serial_reg.h>
33 #include <linux/jiffies.h>
34 
35 MODULE_DESCRIPTION("MIDI serial u16550");
36 MODULE_LICENSE("GPL");
37 
38 #define SNDRV_SERIAL_SOUNDCANVAS 0 /* Roland Soundcanvas; F5 NN selects part */
39 #define SNDRV_SERIAL_MS124T 1      /* Midiator MS-124T */
40 #define SNDRV_SERIAL_MS124W_SA 2   /* Midiator MS-124W in S/A mode */
41 #define SNDRV_SERIAL_MS124W_MB 3   /* Midiator MS-124W in M/B mode */
42 #define SNDRV_SERIAL_GENERIC 4     /* Generic Interface */
43 #define SNDRV_SERIAL_MAX_ADAPTOR SNDRV_SERIAL_GENERIC
44 static const char * const adaptor_names[] = {
45 	"Soundcanvas",
46         "MS-124T",
47 	"MS-124W S/A",
48 	"MS-124W M/B",
49 	"Generic"
50 };
51 
52 #define SNDRV_SERIAL_NORMALBUFF 0 /* Normal blocking buffer operation */
53 #define SNDRV_SERIAL_DROPBUFF   1 /* Non-blocking discard operation */
54 
55 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
56 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
57 static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE; /* Enable this card */
58 static long port[SNDRV_CARDS] = SNDRV_DEFAULT_PORT; /* 0x3f8,0x2f8,0x3e8,0x2e8 */
59 static int irq[SNDRV_CARDS] = SNDRV_DEFAULT_IRQ; 	/* 3,4,5,7,9,10,11,14,15 */
60 static int speed[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 38400}; /* 9600,19200,38400,57600,115200 */
61 static int base[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 115200}; /* baud base */
62 static int outs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};	 /* 1 to 16 */
63 static int ins[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};	/* 1 to 16 */
64 static int adaptor[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = SNDRV_SERIAL_SOUNDCANVAS};
65 static bool droponfull[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS -1)] = SNDRV_SERIAL_NORMALBUFF };
66 
67 module_param_array(index, int, NULL, 0444);
68 MODULE_PARM_DESC(index, "Index value for Serial MIDI.");
69 module_param_array(id, charp, NULL, 0444);
70 MODULE_PARM_DESC(id, "ID string for Serial MIDI.");
71 module_param_array(enable, bool, NULL, 0444);
72 MODULE_PARM_DESC(enable, "Enable UART16550A chip.");
73 module_param_hw_array(port, long, ioport, NULL, 0444);
74 MODULE_PARM_DESC(port, "Port # for UART16550A chip.");
75 module_param_hw_array(irq, int, irq, NULL, 0444);
76 MODULE_PARM_DESC(irq, "IRQ # for UART16550A chip.");
77 module_param_array(speed, int, NULL, 0444);
78 MODULE_PARM_DESC(speed, "Speed in bauds.");
79 module_param_array(base, int, NULL, 0444);
80 MODULE_PARM_DESC(base, "Base for divisor in bauds.");
81 module_param_array(outs, int, NULL, 0444);
82 MODULE_PARM_DESC(outs, "Number of MIDI outputs.");
83 module_param_array(ins, int, NULL, 0444);
84 MODULE_PARM_DESC(ins, "Number of MIDI inputs.");
85 module_param_array(droponfull, bool, NULL, 0444);
86 MODULE_PARM_DESC(droponfull, "Flag to enable drop-on-full buffer mode");
87 
88 module_param_array(adaptor, int, NULL, 0444);
89 MODULE_PARM_DESC(adaptor, "Type of adaptor.");
90 
91 /*#define SNDRV_SERIAL_MS124W_MB_NOCOMBO 1*/  /* Address outs as 0-3 instead of bitmap */
92 
93 #define SNDRV_SERIAL_MAX_OUTS	16		/* max 64, min 16 */
94 #define SNDRV_SERIAL_MAX_INS	16		/* max 64, min 16 */
95 
96 #define TX_BUFF_SIZE		(1<<15)		/* Must be 2^n */
97 #define TX_BUFF_MASK		(TX_BUFF_SIZE - 1)
98 
99 #define SERIAL_MODE_NOT_OPENED 		(0)
100 #define SERIAL_MODE_INPUT_OPEN		(1 << 0)
101 #define SERIAL_MODE_OUTPUT_OPEN		(1 << 1)
102 #define SERIAL_MODE_INPUT_TRIGGERED	(1 << 2)
103 #define SERIAL_MODE_OUTPUT_TRIGGERED	(1 << 3)
104 
105 struct snd_uart16550 {
106 	struct snd_card *card;
107 	struct snd_rawmidi *rmidi;
108 	struct snd_rawmidi_substream *midi_output[SNDRV_SERIAL_MAX_OUTS];
109 	struct snd_rawmidi_substream *midi_input[SNDRV_SERIAL_MAX_INS];
110 
111 	int filemode;		/* open status of file */
112 
113 	spinlock_t open_lock;
114 
115 	int irq;
116 
117 	unsigned long base;
118 	struct resource *res_base;
119 
120 	unsigned int speed;
121 	unsigned int speed_base;
122 	unsigned char divisor;
123 
124 	unsigned char old_divisor_lsb;
125 	unsigned char old_divisor_msb;
126 	unsigned char old_line_ctrl_reg;
127 
128 	/* parameter for using of write loop */
129 	short int fifo_limit;	/* used in uart16550 */
130         short int fifo_count;	/* used in uart16550 */
131 
132 	/* type of adaptor */
133 	int adaptor;
134 
135 	/* inputs */
136 	int prev_in;
137 	unsigned char rstatus;
138 
139 	/* outputs */
140 	int prev_out;
141 	unsigned char prev_status[SNDRV_SERIAL_MAX_OUTS];
142 
143 	/* write buffer and its writing/reading position */
144 	unsigned char tx_buff[TX_BUFF_SIZE];
145 	int buff_in_count;
146         int buff_in;
147         int buff_out;
148         int drop_on_full;
149 
150 	/* wait timer */
151 	unsigned int timer_running:1;
152 	struct timer_list buffer_timer;
153 
154 };
155 
156 static struct platform_device *devices[SNDRV_CARDS];
157 
158 static inline void snd_uart16550_add_timer(struct snd_uart16550 *uart)
159 {
160 	if (!uart->timer_running) {
161 		/* timer 38600bps * 10bit * 16byte */
162 		mod_timer(&uart->buffer_timer, jiffies + (HZ + 255) / 256);
163 		uart->timer_running = 1;
164 	}
165 }
166 
167 static inline void snd_uart16550_del_timer(struct snd_uart16550 *uart)
168 {
169 	if (uart->timer_running) {
170 		del_timer(&uart->buffer_timer);
171 		uart->timer_running = 0;
172 	}
173 }
174 
175 /* This macro is only used in snd_uart16550_io_loop */
176 static inline void snd_uart16550_buffer_output(struct snd_uart16550 *uart)
177 {
178 	unsigned short buff_out = uart->buff_out;
179 	if (uart->buff_in_count > 0) {
180 		outb(uart->tx_buff[buff_out], uart->base + UART_TX);
181 		uart->fifo_count++;
182 		buff_out++;
183 		buff_out &= TX_BUFF_MASK;
184 		uart->buff_out = buff_out;
185 		uart->buff_in_count--;
186 	}
187 }
188 
189 /* This loop should be called with interrupts disabled
190  * We don't want to interrupt this,
191  * as we're already handling an interrupt
192  */
193 static void snd_uart16550_io_loop(struct snd_uart16550 * uart)
194 {
195 	unsigned char c, status;
196 	int substream;
197 
198 	/* recall previous stream */
199 	substream = uart->prev_in;
200 
201 	/* Read Loop */
202 	while ((status = inb(uart->base + UART_LSR)) & UART_LSR_DR) {
203 		/* while receive data ready */
204 		c = inb(uart->base + UART_RX);
205 
206 		/* keep track of last status byte */
207 		if (c & 0x80)
208 			uart->rstatus = c;
209 
210 		/* handle stream switch */
211 		if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
212 			if (uart->rstatus == 0xf5) {
213 				if (c <= SNDRV_SERIAL_MAX_INS && c > 0)
214 					substream = c - 1;
215 				if (c != 0xf5)
216 					/* prevent future bytes from being
217 					   interpreted as streams */
218 					uart->rstatus = 0;
219 			} else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN)
220 				   && uart->midi_input[substream])
221 				snd_rawmidi_receive(uart->midi_input[substream],
222 						    &c, 1);
223 		} else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN) &&
224 			   uart->midi_input[substream])
225 			snd_rawmidi_receive(uart->midi_input[substream], &c, 1);
226 
227 		if (status & UART_LSR_OE)
228 			snd_printk(KERN_WARNING
229 				   "%s: Overrun on device at 0x%lx\n",
230 			       uart->rmidi->name, uart->base);
231 	}
232 
233 	/* remember the last stream */
234 	uart->prev_in = substream;
235 
236 	/* no need of check SERIAL_MODE_OUTPUT_OPEN because if not,
237 	   buffer is never filled. */
238 	/* Check write status */
239 	if (status & UART_LSR_THRE)
240 		uart->fifo_count = 0;
241 	if (uart->adaptor == SNDRV_SERIAL_MS124W_SA
242 	   || uart->adaptor == SNDRV_SERIAL_GENERIC) {
243 		/* Can't use FIFO, must send only when CTS is true */
244 		status = inb(uart->base + UART_MSR);
245 		while (uart->fifo_count == 0 && (status & UART_MSR_CTS) &&
246 		       uart->buff_in_count > 0) {
247 		       snd_uart16550_buffer_output(uart);
248 		       status = inb(uart->base + UART_MSR);
249 		}
250 	} else {
251 		/* Write loop */
252 		while (uart->fifo_count < uart->fifo_limit /* Can we write ? */
253 		       && uart->buff_in_count > 0)	/* Do we want to? */
254 			snd_uart16550_buffer_output(uart);
255 	}
256 	if (uart->irq < 0 && uart->buff_in_count > 0)
257 		snd_uart16550_add_timer(uart);
258 }
259 
260 /* NOTES ON SERVICING INTERUPTS
261  * ---------------------------
262  * After receiving a interrupt, it is important to indicate to the UART that
263  * this has been done.
264  * For a Rx interrupt, this is done by reading the received byte.
265  * For a Tx interrupt this is done by either:
266  * a) Writing a byte
267  * b) Reading the IIR
268  * It is particularly important to read the IIR if a Tx interrupt is received
269  * when there is no data in tx_buff[], as in this case there no other
270  * indication that the interrupt has been serviced, and it remains outstanding
271  * indefinitely. This has the curious side effect that and no further interrupts
272  * will be generated from this device AT ALL!!.
273  * It is also desirable to clear outstanding interrupts when the device is
274  * opened/closed.
275  *
276  *
277  * Note that some devices need OUT2 to be set before they will generate
278  * interrupts at all. (Possibly tied to an internal pull-up on CTS?)
279  */
280 static irqreturn_t snd_uart16550_interrupt(int irq, void *dev_id)
281 {
282 	struct snd_uart16550 *uart;
283 
284 	uart = dev_id;
285 	spin_lock(&uart->open_lock);
286 	if (uart->filemode == SERIAL_MODE_NOT_OPENED) {
287 		spin_unlock(&uart->open_lock);
288 		return IRQ_NONE;
289 	}
290 	/* indicate to the UART that the interrupt has been serviced */
291 	inb(uart->base + UART_IIR);
292 	snd_uart16550_io_loop(uart);
293 	spin_unlock(&uart->open_lock);
294 	return IRQ_HANDLED;
295 }
296 
297 /* When the polling mode, this function calls snd_uart16550_io_loop. */
298 static void snd_uart16550_buffer_timer(struct timer_list *t)
299 {
300 	unsigned long flags;
301 	struct snd_uart16550 *uart;
302 
303 	uart = from_timer(uart, t, buffer_timer);
304 	spin_lock_irqsave(&uart->open_lock, flags);
305 	snd_uart16550_del_timer(uart);
306 	snd_uart16550_io_loop(uart);
307 	spin_unlock_irqrestore(&uart->open_lock, flags);
308 }
309 
310 /*
311  *  this method probes, if an uart sits on given port
312  *  return 0 if found
313  *  return negative error if not found
314  */
315 static int snd_uart16550_detect(struct snd_uart16550 *uart)
316 {
317 	unsigned long io_base = uart->base;
318 	int ok;
319 	unsigned char c;
320 
321 	/* Do some vague tests for the presence of the uart */
322 	if (io_base == 0 || io_base == SNDRV_AUTO_PORT) {
323 		return -ENODEV;	/* Not configured */
324 	}
325 
326 	uart->res_base = request_region(io_base, 8, "Serial MIDI");
327 	if (uart->res_base == NULL) {
328 		snd_printk(KERN_ERR "u16550: can't grab port 0x%lx\n", io_base);
329 		return -EBUSY;
330 	}
331 
332 	/* uart detected unless one of the following tests should fail */
333 	ok = 1;
334 	/* 8 data-bits, 1 stop-bit, parity off, DLAB = 0 */
335 	outb(UART_LCR_WLEN8, io_base + UART_LCR); /* Line Control Register */
336 	c = inb(io_base + UART_IER);
337 	/* The top four bits of the IER should always == 0 */
338 	if ((c & 0xf0) != 0)
339 		ok = 0;		/* failed */
340 
341 	outb(0xaa, io_base + UART_SCR);
342 	/* Write arbitrary data into the scratch reg */
343 	c = inb(io_base + UART_SCR);
344 	/* If it comes back, it's OK */
345 	if (c != 0xaa)
346 		ok = 0;		/* failed */
347 
348 	outb(0x55, io_base + UART_SCR);
349 	/* Write arbitrary data into the scratch reg */
350 	c = inb(io_base + UART_SCR);
351 	/* If it comes back, it's OK */
352 	if (c != 0x55)
353 		ok = 0;		/* failed */
354 
355 	return ok;
356 }
357 
358 static void snd_uart16550_do_open(struct snd_uart16550 * uart)
359 {
360 	char byte;
361 
362 	/* Initialize basic variables */
363 	uart->buff_in_count = 0;
364 	uart->buff_in = 0;
365 	uart->buff_out = 0;
366 	uart->fifo_limit = 1;
367 	uart->fifo_count = 0;
368 	uart->timer_running = 0;
369 
370 	outb(UART_FCR_ENABLE_FIFO	/* Enable FIFO's (if available) */
371 	     | UART_FCR_CLEAR_RCVR	/* Clear receiver FIFO */
372 	     | UART_FCR_CLEAR_XMIT	/* Clear transmitter FIFO */
373 	     | UART_FCR_TRIGGER_4	/* Set FIFO trigger at 4-bytes */
374 	/* NOTE: interrupt generated after T=(time)4-bytes
375 	 * if less than UART_FCR_TRIGGER bytes received
376 	 */
377 	     ,uart->base + UART_FCR);	/* FIFO Control Register */
378 
379 	if ((inb(uart->base + UART_IIR) & 0xf0) == 0xc0)
380 		uart->fifo_limit = 16;
381 	if (uart->divisor != 0) {
382 		uart->old_line_ctrl_reg = inb(uart->base + UART_LCR);
383 		outb(UART_LCR_DLAB	/* Divisor latch access bit */
384 		     ,uart->base + UART_LCR);	/* Line Control Register */
385 		uart->old_divisor_lsb = inb(uart->base + UART_DLL);
386 		uart->old_divisor_msb = inb(uart->base + UART_DLM);
387 
388 		outb(uart->divisor
389 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
390 		outb(0
391 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
392 		/* DLAB is reset to 0 in next outb() */
393 	}
394 	/* Set serial parameters (parity off, etc) */
395 	outb(UART_LCR_WLEN8	/* 8 data-bits */
396 	     | 0		/* 1 stop-bit */
397 	     | 0		/* parity off */
398 	     | 0		/* DLAB = 0 */
399 	     ,uart->base + UART_LCR);	/* Line Control Register */
400 
401 	switch (uart->adaptor) {
402 	default:
403 		outb(UART_MCR_RTS	/* Set Request-To-Send line active */
404 		     | UART_MCR_DTR	/* Set Data-Terminal-Ready line active */
405 		     | UART_MCR_OUT2	/* Set OUT2 - not always required, but when
406 					 * it is, it is ESSENTIAL for enabling interrupts
407 				 */
408 		     ,uart->base + UART_MCR);	/* Modem Control Register */
409 		break;
410 	case SNDRV_SERIAL_MS124W_SA:
411 	case SNDRV_SERIAL_MS124W_MB:
412 		/* MS-124W can draw power from RTS and DTR if they
413 		   are in opposite states. */
414 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | UART_MCR_OUT2,
415 		     uart->base + UART_MCR);
416 		break;
417 	case SNDRV_SERIAL_MS124T:
418 		/* MS-124T can draw power from RTS and/or DTR (preferably
419 		   both) if they are both asserted. */
420 		outb(UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2,
421 		     uart->base + UART_MCR);
422 		break;
423 	}
424 
425 	if (uart->irq < 0) {
426 		byte = (0 & UART_IER_RDI)	/* Disable Receiver data interrupt */
427 		    |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
428 		    ;
429 	} else if (uart->adaptor == SNDRV_SERIAL_MS124W_SA) {
430 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
431 		    | UART_IER_MSI	/* Enable Modem status interrupt */
432 		    ;
433 	} else if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
434 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
435 		    | UART_IER_MSI	/* Enable Modem status interrupt */
436 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
437 		    ;
438 	} else {
439 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
440 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
441 		    ;
442 	}
443 	outb(byte, uart->base + UART_IER);	/* Interrupt enable Register */
444 
445 	inb(uart->base + UART_LSR);	/* Clear any pre-existing overrun indication */
446 	inb(uart->base + UART_IIR);	/* Clear any pre-existing transmit interrupt */
447 	inb(uart->base + UART_RX);	/* Clear any pre-existing receive interrupt */
448 }
449 
450 static void snd_uart16550_do_close(struct snd_uart16550 * uart)
451 {
452 	if (uart->irq < 0)
453 		snd_uart16550_del_timer(uart);
454 
455 	/* NOTE: may need to disable interrupts before de-registering out handler.
456 	 * For now, the consequences are harmless.
457 	 */
458 
459 	outb((0 & UART_IER_RDI)		/* Disable Receiver data interrupt */
460 	     |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
461 	     ,uart->base + UART_IER);	/* Interrupt enable Register */
462 
463 	switch (uart->adaptor) {
464 	default:
465 		outb((0 & UART_MCR_RTS)		/* Deactivate Request-To-Send line  */
466 		     |(0 & UART_MCR_DTR)	/* Deactivate Data-Terminal-Ready line */
467 		     |(0 & UART_MCR_OUT2)	/* Deactivate OUT2 */
468 		     ,uart->base + UART_MCR);	/* Modem Control Register */
469 	  break;
470 	case SNDRV_SERIAL_MS124W_SA:
471 	case SNDRV_SERIAL_MS124W_MB:
472 		/* MS-124W can draw power from RTS and DTR if they
473 		   are in opposite states; leave it powered. */
474 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | (0&UART_MCR_OUT2),
475 		     uart->base + UART_MCR);
476 		break;
477 	case SNDRV_SERIAL_MS124T:
478 		/* MS-124T can draw power from RTS and/or DTR (preferably
479 		   both) if they are both asserted; leave it powered. */
480 		outb(UART_MCR_RTS | UART_MCR_DTR | (0&UART_MCR_OUT2),
481 		     uart->base + UART_MCR);
482 		break;
483 	}
484 
485 	inb(uart->base + UART_IIR);	/* Clear any outstanding interrupts */
486 
487 	/* Restore old divisor */
488 	if (uart->divisor != 0) {
489 		outb(UART_LCR_DLAB		/* Divisor latch access bit */
490 		     ,uart->base + UART_LCR);	/* Line Control Register */
491 		outb(uart->old_divisor_lsb
492 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
493 		outb(uart->old_divisor_msb
494 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
495 		/* Restore old LCR (data bits, stop bits, parity, DLAB) */
496 		outb(uart->old_line_ctrl_reg
497 		     ,uart->base + UART_LCR);	/* Line Control Register */
498 	}
499 }
500 
501 static int snd_uart16550_input_open(struct snd_rawmidi_substream *substream)
502 {
503 	unsigned long flags;
504 	struct snd_uart16550 *uart = substream->rmidi->private_data;
505 
506 	spin_lock_irqsave(&uart->open_lock, flags);
507 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
508 		snd_uart16550_do_open(uart);
509 	uart->filemode |= SERIAL_MODE_INPUT_OPEN;
510 	uart->midi_input[substream->number] = substream;
511 	spin_unlock_irqrestore(&uart->open_lock, flags);
512 	return 0;
513 }
514 
515 static int snd_uart16550_input_close(struct snd_rawmidi_substream *substream)
516 {
517 	unsigned long flags;
518 	struct snd_uart16550 *uart = substream->rmidi->private_data;
519 
520 	spin_lock_irqsave(&uart->open_lock, flags);
521 	uart->filemode &= ~SERIAL_MODE_INPUT_OPEN;
522 	uart->midi_input[substream->number] = NULL;
523 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
524 		snd_uart16550_do_close(uart);
525 	spin_unlock_irqrestore(&uart->open_lock, flags);
526 	return 0;
527 }
528 
529 static void snd_uart16550_input_trigger(struct snd_rawmidi_substream *substream,
530 					int up)
531 {
532 	unsigned long flags;
533 	struct snd_uart16550 *uart = substream->rmidi->private_data;
534 
535 	spin_lock_irqsave(&uart->open_lock, flags);
536 	if (up)
537 		uart->filemode |= SERIAL_MODE_INPUT_TRIGGERED;
538 	else
539 		uart->filemode &= ~SERIAL_MODE_INPUT_TRIGGERED;
540 	spin_unlock_irqrestore(&uart->open_lock, flags);
541 }
542 
543 static int snd_uart16550_output_open(struct snd_rawmidi_substream *substream)
544 {
545 	unsigned long flags;
546 	struct snd_uart16550 *uart = substream->rmidi->private_data;
547 
548 	spin_lock_irqsave(&uart->open_lock, flags);
549 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
550 		snd_uart16550_do_open(uart);
551 	uart->filemode |= SERIAL_MODE_OUTPUT_OPEN;
552 	uart->midi_output[substream->number] = substream;
553 	spin_unlock_irqrestore(&uart->open_lock, flags);
554 	return 0;
555 };
556 
557 static int snd_uart16550_output_close(struct snd_rawmidi_substream *substream)
558 {
559 	unsigned long flags;
560 	struct snd_uart16550 *uart = substream->rmidi->private_data;
561 
562 	spin_lock_irqsave(&uart->open_lock, flags);
563 	uart->filemode &= ~SERIAL_MODE_OUTPUT_OPEN;
564 	uart->midi_output[substream->number] = NULL;
565 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
566 		snd_uart16550_do_close(uart);
567 	spin_unlock_irqrestore(&uart->open_lock, flags);
568 	return 0;
569 };
570 
571 static inline int snd_uart16550_buffer_can_write(struct snd_uart16550 *uart,
572 						 int Num)
573 {
574 	if (uart->buff_in_count + Num < TX_BUFF_SIZE)
575 		return 1;
576 	else
577 		return 0;
578 }
579 
580 static inline int snd_uart16550_write_buffer(struct snd_uart16550 *uart,
581 					     unsigned char byte)
582 {
583 	unsigned short buff_in = uart->buff_in;
584 	if (uart->buff_in_count < TX_BUFF_SIZE) {
585 		uart->tx_buff[buff_in] = byte;
586 		buff_in++;
587 		buff_in &= TX_BUFF_MASK;
588 		uart->buff_in = buff_in;
589 		uart->buff_in_count++;
590 		if (uart->irq < 0) /* polling mode */
591 			snd_uart16550_add_timer(uart);
592 		return 1;
593 	} else
594 		return 0;
595 }
596 
597 static int snd_uart16550_output_byte(struct snd_uart16550 *uart,
598 				     struct snd_rawmidi_substream *substream,
599 				     unsigned char midi_byte)
600 {
601 	if (uart->buff_in_count == 0                    /* Buffer empty? */
602 	    && ((uart->adaptor != SNDRV_SERIAL_MS124W_SA &&
603 	    uart->adaptor != SNDRV_SERIAL_GENERIC) ||
604 		(uart->fifo_count == 0                  /* FIFO empty? */
605 		 && (inb(uart->base + UART_MSR) & UART_MSR_CTS)))) { /* CTS? */
606 
607 	        /* Tx Buffer Empty - try to write immediately */
608 		if ((inb(uart->base + UART_LSR) & UART_LSR_THRE) != 0) {
609 		        /* Transmitter holding register (and Tx FIFO) empty */
610 		        uart->fifo_count = 1;
611 			outb(midi_byte, uart->base + UART_TX);
612 		} else {
613 		        if (uart->fifo_count < uart->fifo_limit) {
614 			        uart->fifo_count++;
615 				outb(midi_byte, uart->base + UART_TX);
616 			} else {
617 			        /* Cannot write (buffer empty) -
618 				 * put char in buffer */
619 				snd_uart16550_write_buffer(uart, midi_byte);
620 			}
621 		}
622 	} else {
623 		if (!snd_uart16550_write_buffer(uart, midi_byte)) {
624 			snd_printk(KERN_WARNING
625 				   "%s: Buffer overrun on device at 0x%lx\n",
626 				   uart->rmidi->name, uart->base);
627 			return 0;
628 		}
629 	}
630 
631 	return 1;
632 }
633 
634 static void snd_uart16550_output_write(struct snd_rawmidi_substream *substream)
635 {
636 	unsigned long flags;
637 	unsigned char midi_byte, addr_byte;
638 	struct snd_uart16550 *uart = substream->rmidi->private_data;
639 	char first;
640 	static unsigned long lasttime = 0;
641 
642 	/* Interrupts are disabled during the updating of the tx_buff,
643 	 * since it is 'bad' to have two processes updating the same
644 	 * variables (ie buff_in & buff_out)
645 	 */
646 
647 	spin_lock_irqsave(&uart->open_lock, flags);
648 
649 	if (uart->irq < 0)	/* polling */
650 		snd_uart16550_io_loop(uart);
651 
652 	if (uart->adaptor == SNDRV_SERIAL_MS124W_MB) {
653 		while (1) {
654 			/* buffer full? */
655 			/* in this mode we need two bytes of space */
656 			if (uart->buff_in_count > TX_BUFF_SIZE - 2)
657 				break;
658 			if (snd_rawmidi_transmit(substream, &midi_byte, 1) != 1)
659 				break;
660 #ifdef SNDRV_SERIAL_MS124W_MB_NOCOMBO
661 			/* select exactly one of the four ports */
662 			addr_byte = (1 << (substream->number + 4)) | 0x08;
663 #else
664 			/* select any combination of the four ports */
665 			addr_byte = (substream->number << 4) | 0x08;
666 			/* ...except none */
667 			if (addr_byte == 0x08)
668 				addr_byte = 0xf8;
669 #endif
670 			snd_uart16550_output_byte(uart, substream, addr_byte);
671 			/* send midi byte */
672 			snd_uart16550_output_byte(uart, substream, midi_byte);
673 		}
674 	} else {
675 		first = 0;
676 		while (snd_rawmidi_transmit_peek(substream, &midi_byte, 1) == 1) {
677 			/* Also send F5 after 3 seconds with no data
678 			 * to handle device disconnect */
679 			if (first == 0 &&
680 			    (uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS ||
681 			     uart->adaptor == SNDRV_SERIAL_GENERIC) &&
682 			    (uart->prev_out != substream->number ||
683 			     time_after(jiffies, lasttime + 3*HZ))) {
684 
685 				if (snd_uart16550_buffer_can_write(uart, 3)) {
686 					/* Roland Soundcanvas part selection */
687 					/* If this substream of the data is
688 					 * different previous substream
689 					 * in this uart, send the change part
690 					 * event
691 					 */
692 					uart->prev_out = substream->number;
693 					/* change part */
694 					snd_uart16550_output_byte(uart, substream,
695 								  0xf5);
696 					/* data */
697 					snd_uart16550_output_byte(uart, substream,
698 								  uart->prev_out + 1);
699 					/* If midi_byte is a data byte,
700 					 * send the previous status byte */
701 					if (midi_byte < 0x80 &&
702 					    uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS)
703 						snd_uart16550_output_byte(uart, substream, uart->prev_status[uart->prev_out]);
704 				} else if (!uart->drop_on_full)
705 					break;
706 
707 			}
708 
709 			/* send midi byte */
710 			if (!snd_uart16550_output_byte(uart, substream, midi_byte) &&
711 			    !uart->drop_on_full )
712 				break;
713 
714 			if (midi_byte >= 0x80 && midi_byte < 0xf0)
715 				uart->prev_status[uart->prev_out] = midi_byte;
716 			first = 1;
717 
718 			snd_rawmidi_transmit_ack( substream, 1 );
719 		}
720 		lasttime = jiffies;
721 	}
722 	spin_unlock_irqrestore(&uart->open_lock, flags);
723 }
724 
725 static void snd_uart16550_output_trigger(struct snd_rawmidi_substream *substream,
726 					 int up)
727 {
728 	unsigned long flags;
729 	struct snd_uart16550 *uart = substream->rmidi->private_data;
730 
731 	spin_lock_irqsave(&uart->open_lock, flags);
732 	if (up)
733 		uart->filemode |= SERIAL_MODE_OUTPUT_TRIGGERED;
734 	else
735 		uart->filemode &= ~SERIAL_MODE_OUTPUT_TRIGGERED;
736 	spin_unlock_irqrestore(&uart->open_lock, flags);
737 	if (up)
738 		snd_uart16550_output_write(substream);
739 }
740 
741 static const struct snd_rawmidi_ops snd_uart16550_output =
742 {
743 	.open =		snd_uart16550_output_open,
744 	.close =	snd_uart16550_output_close,
745 	.trigger =	snd_uart16550_output_trigger,
746 };
747 
748 static const struct snd_rawmidi_ops snd_uart16550_input =
749 {
750 	.open =		snd_uart16550_input_open,
751 	.close =	snd_uart16550_input_close,
752 	.trigger =	snd_uart16550_input_trigger,
753 };
754 
755 static int snd_uart16550_free(struct snd_uart16550 *uart)
756 {
757 	if (uart->irq >= 0)
758 		free_irq(uart->irq, uart);
759 	release_and_free_resource(uart->res_base);
760 	kfree(uart);
761 	return 0;
762 };
763 
764 static int snd_uart16550_dev_free(struct snd_device *device)
765 {
766 	struct snd_uart16550 *uart = device->device_data;
767 	return snd_uart16550_free(uart);
768 }
769 
770 static int snd_uart16550_create(struct snd_card *card,
771 				unsigned long iobase,
772 				int irq,
773 				unsigned int speed,
774 				unsigned int base,
775 				int adaptor,
776 				int droponfull,
777 				struct snd_uart16550 **ruart)
778 {
779 	static const struct snd_device_ops ops = {
780 		.dev_free =	snd_uart16550_dev_free,
781 	};
782 	struct snd_uart16550 *uart;
783 	int err;
784 
785 
786 	if ((uart = kzalloc(sizeof(*uart), GFP_KERNEL)) == NULL)
787 		return -ENOMEM;
788 	uart->adaptor = adaptor;
789 	uart->card = card;
790 	spin_lock_init(&uart->open_lock);
791 	uart->irq = -1;
792 	uart->base = iobase;
793 	uart->drop_on_full = droponfull;
794 
795 	if ((err = snd_uart16550_detect(uart)) <= 0) {
796 		printk(KERN_ERR "no UART detected at 0x%lx\n", iobase);
797 		snd_uart16550_free(uart);
798 		return -ENODEV;
799 	}
800 
801 	if (irq >= 0 && irq != SNDRV_AUTO_IRQ) {
802 		if (request_irq(irq, snd_uart16550_interrupt,
803 				0, "Serial MIDI", uart)) {
804 			snd_printk(KERN_WARNING
805 				   "irq %d busy. Using Polling.\n", irq);
806 		} else {
807 			uart->irq = irq;
808 		}
809 	}
810 	uart->divisor = base / speed;
811 	uart->speed = base / (unsigned int)uart->divisor;
812 	uart->speed_base = base;
813 	uart->prev_out = -1;
814 	uart->prev_in = 0;
815 	uart->rstatus = 0;
816 	memset(uart->prev_status, 0x80, sizeof(unsigned char) * SNDRV_SERIAL_MAX_OUTS);
817 	timer_setup(&uart->buffer_timer, snd_uart16550_buffer_timer, 0);
818 	uart->timer_running = 0;
819 
820 	/* Register device */
821 	if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, uart, &ops)) < 0) {
822 		snd_uart16550_free(uart);
823 		return err;
824 	}
825 
826 	switch (uart->adaptor) {
827 	case SNDRV_SERIAL_MS124W_SA:
828 	case SNDRV_SERIAL_MS124W_MB:
829 		/* MS-124W can draw power from RTS and DTR if they
830 		   are in opposite states. */
831 		outb(UART_MCR_RTS | (0&UART_MCR_DTR), uart->base + UART_MCR);
832 		break;
833 	case SNDRV_SERIAL_MS124T:
834 		/* MS-124T can draw power from RTS and/or DTR (preferably
835 		   both) if they are asserted. */
836 		outb(UART_MCR_RTS | UART_MCR_DTR, uart->base + UART_MCR);
837 		break;
838 	default:
839 		break;
840 	}
841 
842 	if (ruart)
843 		*ruart = uart;
844 
845 	return 0;
846 }
847 
848 static void snd_uart16550_substreams(struct snd_rawmidi_str *stream)
849 {
850 	struct snd_rawmidi_substream *substream;
851 
852 	list_for_each_entry(substream, &stream->substreams, list) {
853 		sprintf(substream->name, "Serial MIDI %d", substream->number + 1);
854 	}
855 }
856 
857 static int snd_uart16550_rmidi(struct snd_uart16550 *uart, int device,
858 			       int outs, int ins,
859 			       struct snd_rawmidi **rmidi)
860 {
861 	struct snd_rawmidi *rrawmidi;
862 	int err;
863 
864 	err = snd_rawmidi_new(uart->card, "UART Serial MIDI", device,
865 			      outs, ins, &rrawmidi);
866 	if (err < 0)
867 		return err;
868 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_INPUT,
869 			    &snd_uart16550_input);
870 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
871 			    &snd_uart16550_output);
872 	strcpy(rrawmidi->name, "Serial MIDI");
873 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT]);
874 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT]);
875 	rrawmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
876 			       SNDRV_RAWMIDI_INFO_INPUT |
877 			       SNDRV_RAWMIDI_INFO_DUPLEX;
878 	rrawmidi->private_data = uart;
879 	if (rmidi)
880 		*rmidi = rrawmidi;
881 	return 0;
882 }
883 
884 static int snd_serial_probe(struct platform_device *devptr)
885 {
886 	struct snd_card *card;
887 	struct snd_uart16550 *uart;
888 	int err;
889 	int dev = devptr->id;
890 
891 	switch (adaptor[dev]) {
892 	case SNDRV_SERIAL_SOUNDCANVAS:
893 		ins[dev] = 1;
894 		break;
895 	case SNDRV_SERIAL_MS124T:
896 	case SNDRV_SERIAL_MS124W_SA:
897 		outs[dev] = 1;
898 		ins[dev] = 1;
899 		break;
900 	case SNDRV_SERIAL_MS124W_MB:
901 		outs[dev] = 16;
902 		ins[dev] = 1;
903 		break;
904 	case SNDRV_SERIAL_GENERIC:
905 		break;
906 	default:
907 		snd_printk(KERN_ERR
908 			   "Adaptor type is out of range 0-%d (%d)\n",
909 			   SNDRV_SERIAL_MAX_ADAPTOR, adaptor[dev]);
910 		return -ENODEV;
911 	}
912 
913 	if (outs[dev] < 1 || outs[dev] > SNDRV_SERIAL_MAX_OUTS) {
914 		snd_printk(KERN_ERR
915 			   "Count of outputs is out of range 1-%d (%d)\n",
916 			   SNDRV_SERIAL_MAX_OUTS, outs[dev]);
917 		return -ENODEV;
918 	}
919 
920 	if (ins[dev] < 1 || ins[dev] > SNDRV_SERIAL_MAX_INS) {
921 		snd_printk(KERN_ERR
922 			   "Count of inputs is out of range 1-%d (%d)\n",
923 			   SNDRV_SERIAL_MAX_INS, ins[dev]);
924 		return -ENODEV;
925 	}
926 
927 	err  = snd_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
928 			    0, &card);
929 	if (err < 0)
930 		return err;
931 
932 	strcpy(card->driver, "Serial");
933 	strcpy(card->shortname, "Serial MIDI (UART16550A)");
934 
935 	if ((err = snd_uart16550_create(card,
936 					port[dev],
937 					irq[dev],
938 					speed[dev],
939 					base[dev],
940 					adaptor[dev],
941 					droponfull[dev],
942 					&uart)) < 0)
943 		goto _err;
944 
945 	err = snd_uart16550_rmidi(uart, 0, outs[dev], ins[dev], &uart->rmidi);
946 	if (err < 0)
947 		goto _err;
948 
949 	sprintf(card->longname, "%s [%s] at %#lx, irq %d",
950 		card->shortname,
951 		adaptor_names[uart->adaptor],
952 		uart->base,
953 		uart->irq);
954 
955 	if ((err = snd_card_register(card)) < 0)
956 		goto _err;
957 
958 	platform_set_drvdata(devptr, card);
959 	return 0;
960 
961  _err:
962 	snd_card_free(card);
963 	return err;
964 }
965 
966 static int snd_serial_remove(struct platform_device *devptr)
967 {
968 	snd_card_free(platform_get_drvdata(devptr));
969 	return 0;
970 }
971 
972 #define SND_SERIAL_DRIVER	"snd_serial_u16550"
973 
974 static struct platform_driver snd_serial_driver = {
975 	.probe		= snd_serial_probe,
976 	.remove		=  snd_serial_remove,
977 	.driver		= {
978 		.name	= SND_SERIAL_DRIVER,
979 	},
980 };
981 
982 static void snd_serial_unregister_all(void)
983 {
984 	int i;
985 
986 	for (i = 0; i < ARRAY_SIZE(devices); ++i)
987 		platform_device_unregister(devices[i]);
988 	platform_driver_unregister(&snd_serial_driver);
989 }
990 
991 static int __init alsa_card_serial_init(void)
992 {
993 	int i, cards, err;
994 
995 	if ((err = platform_driver_register(&snd_serial_driver)) < 0)
996 		return err;
997 
998 	cards = 0;
999 	for (i = 0; i < SNDRV_CARDS; i++) {
1000 		struct platform_device *device;
1001 		if (! enable[i])
1002 			continue;
1003 		device = platform_device_register_simple(SND_SERIAL_DRIVER,
1004 							 i, NULL, 0);
1005 		if (IS_ERR(device))
1006 			continue;
1007 		if (!platform_get_drvdata(device)) {
1008 			platform_device_unregister(device);
1009 			continue;
1010 		}
1011 		devices[i] = device;
1012 		cards++;
1013 	}
1014 	if (! cards) {
1015 #ifdef MODULE
1016 		printk(KERN_ERR "serial midi soundcard not found or device busy\n");
1017 #endif
1018 		snd_serial_unregister_all();
1019 		return -ENODEV;
1020 	}
1021 	return 0;
1022 }
1023 
1024 static void __exit alsa_card_serial_exit(void)
1025 {
1026 	snd_serial_unregister_all();
1027 }
1028 
1029 module_init(alsa_card_serial_init)
1030 module_exit(alsa_card_serial_exit)
1031