xref: /linux/sound/drivers/serial-u16550.c (revision 3ea5eb68b9d624935108b5e696859304edfac202)
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 
119 	unsigned int speed;
120 	unsigned int speed_base;
121 	unsigned char divisor;
122 
123 	unsigned char old_divisor_lsb;
124 	unsigned char old_divisor_msb;
125 	unsigned char old_line_ctrl_reg;
126 
127 	/* parameter for using of write loop */
128 	short int fifo_limit;	/* used in uart16550 */
129         short int fifo_count;	/* used in uart16550 */
130 
131 	/* type of adaptor */
132 	int adaptor;
133 
134 	/* inputs */
135 	int prev_in;
136 	unsigned char rstatus;
137 
138 	/* outputs */
139 	int prev_out;
140 	unsigned char prev_status[SNDRV_SERIAL_MAX_OUTS];
141 
142 	/* write buffer and its writing/reading position */
143 	unsigned char tx_buff[TX_BUFF_SIZE];
144 	int buff_in_count;
145         int buff_in;
146         int buff_out;
147         int drop_on_full;
148 
149 	/* wait timer */
150 	unsigned int timer_running:1;
151 	struct timer_list buffer_timer;
152 
153 };
154 
155 static struct platform_device *devices[SNDRV_CARDS];
156 
157 static inline void snd_uart16550_add_timer(struct snd_uart16550 *uart)
158 {
159 	if (!uart->timer_running) {
160 		/* timer 38600bps * 10bit * 16byte */
161 		mod_timer(&uart->buffer_timer, jiffies + (HZ + 255) / 256);
162 		uart->timer_running = 1;
163 	}
164 }
165 
166 static inline void snd_uart16550_del_timer(struct snd_uart16550 *uart)
167 {
168 	if (uart->timer_running) {
169 		del_timer(&uart->buffer_timer);
170 		uart->timer_running = 0;
171 	}
172 }
173 
174 /* This macro is only used in snd_uart16550_io_loop */
175 static inline void snd_uart16550_buffer_output(struct snd_uart16550 *uart)
176 {
177 	unsigned short buff_out = uart->buff_out;
178 	if (uart->buff_in_count > 0) {
179 		outb(uart->tx_buff[buff_out], uart->base + UART_TX);
180 		uart->fifo_count++;
181 		buff_out++;
182 		buff_out &= TX_BUFF_MASK;
183 		uart->buff_out = buff_out;
184 		uart->buff_in_count--;
185 	}
186 }
187 
188 /* This loop should be called with interrupts disabled
189  * We don't want to interrupt this,
190  * as we're already handling an interrupt
191  */
192 static void snd_uart16550_io_loop(struct snd_uart16550 * uart)
193 {
194 	unsigned char c, status;
195 	int substream;
196 
197 	/* recall previous stream */
198 	substream = uart->prev_in;
199 
200 	/* Read Loop */
201 	while ((status = inb(uart->base + UART_LSR)) & UART_LSR_DR) {
202 		/* while receive data ready */
203 		c = inb(uart->base + UART_RX);
204 
205 		/* keep track of last status byte */
206 		if (c & 0x80)
207 			uart->rstatus = c;
208 
209 		/* handle stream switch */
210 		if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
211 			if (uart->rstatus == 0xf5) {
212 				if (c <= SNDRV_SERIAL_MAX_INS && c > 0)
213 					substream = c - 1;
214 				if (c != 0xf5)
215 					/* prevent future bytes from being
216 					   interpreted as streams */
217 					uart->rstatus = 0;
218 			} else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN)
219 				   && uart->midi_input[substream])
220 				snd_rawmidi_receive(uart->midi_input[substream],
221 						    &c, 1);
222 		} else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN) &&
223 			   uart->midi_input[substream])
224 			snd_rawmidi_receive(uart->midi_input[substream], &c, 1);
225 
226 		if (status & UART_LSR_OE)
227 			dev_warn(uart->card->dev,
228 				 "%s: Overrun on device at 0x%lx\n",
229 				 uart->rmidi->name, uart->base);
230 	}
231 
232 	/* remember the last stream */
233 	uart->prev_in = substream;
234 
235 	/* no need of check SERIAL_MODE_OUTPUT_OPEN because if not,
236 	   buffer is never filled. */
237 	/* Check write status */
238 	if (status & UART_LSR_THRE)
239 		uart->fifo_count = 0;
240 	if (uart->adaptor == SNDRV_SERIAL_MS124W_SA
241 	   || uart->adaptor == SNDRV_SERIAL_GENERIC) {
242 		/* Can't use FIFO, must send only when CTS is true */
243 		status = inb(uart->base + UART_MSR);
244 		while (uart->fifo_count == 0 && (status & UART_MSR_CTS) &&
245 		       uart->buff_in_count > 0) {
246 		       snd_uart16550_buffer_output(uart);
247 		       status = inb(uart->base + UART_MSR);
248 		}
249 	} else {
250 		/* Write loop */
251 		while (uart->fifo_count < uart->fifo_limit /* Can we write ? */
252 		       && uart->buff_in_count > 0)	/* Do we want to? */
253 			snd_uart16550_buffer_output(uart);
254 	}
255 	if (uart->irq < 0 && uart->buff_in_count > 0)
256 		snd_uart16550_add_timer(uart);
257 }
258 
259 /* NOTES ON SERVICING INTERUPTS
260  * ---------------------------
261  * After receiving a interrupt, it is important to indicate to the UART that
262  * this has been done.
263  * For a Rx interrupt, this is done by reading the received byte.
264  * For a Tx interrupt this is done by either:
265  * a) Writing a byte
266  * b) Reading the IIR
267  * It is particularly important to read the IIR if a Tx interrupt is received
268  * when there is no data in tx_buff[], as in this case there no other
269  * indication that the interrupt has been serviced, and it remains outstanding
270  * indefinitely. This has the curious side effect that and no further interrupts
271  * will be generated from this device AT ALL!!.
272  * It is also desirable to clear outstanding interrupts when the device is
273  * opened/closed.
274  *
275  *
276  * Note that some devices need OUT2 to be set before they will generate
277  * interrupts at all. (Possibly tied to an internal pull-up on CTS?)
278  */
279 static irqreturn_t snd_uart16550_interrupt(int irq, void *dev_id)
280 {
281 	struct snd_uart16550 *uart;
282 
283 	uart = dev_id;
284 	spin_lock(&uart->open_lock);
285 	if (uart->filemode == SERIAL_MODE_NOT_OPENED) {
286 		spin_unlock(&uart->open_lock);
287 		return IRQ_NONE;
288 	}
289 	/* indicate to the UART that the interrupt has been serviced */
290 	inb(uart->base + UART_IIR);
291 	snd_uart16550_io_loop(uart);
292 	spin_unlock(&uart->open_lock);
293 	return IRQ_HANDLED;
294 }
295 
296 /* When the polling mode, this function calls snd_uart16550_io_loop. */
297 static void snd_uart16550_buffer_timer(struct timer_list *t)
298 {
299 	unsigned long flags;
300 	struct snd_uart16550 *uart;
301 
302 	uart = from_timer(uart, t, buffer_timer);
303 	spin_lock_irqsave(&uart->open_lock, flags);
304 	snd_uart16550_del_timer(uart);
305 	snd_uart16550_io_loop(uart);
306 	spin_unlock_irqrestore(&uart->open_lock, flags);
307 }
308 
309 /*
310  *  this method probes, if an uart sits on given port
311  *  return 0 if found
312  *  return negative error if not found
313  */
314 static int snd_uart16550_detect(struct snd_uart16550 *uart)
315 {
316 	unsigned long io_base = uart->base;
317 	int ok;
318 	unsigned char c;
319 
320 	/* Do some vague tests for the presence of the uart */
321 	if (io_base == 0 || io_base == SNDRV_AUTO_PORT) {
322 		return -ENODEV;	/* Not configured */
323 	}
324 
325 	if (!devm_request_region(uart->card->dev, io_base, 8, "Serial MIDI")) {
326 		dev_err(uart->card->dev,
327 			"u16550: can't grab port 0x%lx\n", io_base);
328 		return -EBUSY;
329 	}
330 
331 	/* uart detected unless one of the following tests should fail */
332 	ok = 1;
333 	/* 8 data-bits, 1 stop-bit, parity off, DLAB = 0 */
334 	outb(UART_LCR_WLEN8, io_base + UART_LCR); /* Line Control Register */
335 	c = inb(io_base + UART_IER);
336 	/* The top four bits of the IER should always == 0 */
337 	if ((c & 0xf0) != 0)
338 		ok = 0;		/* failed */
339 
340 	outb(0xaa, io_base + UART_SCR);
341 	/* Write arbitrary data into the scratch reg */
342 	c = inb(io_base + UART_SCR);
343 	/* If it comes back, it's OK */
344 	if (c != 0xaa)
345 		ok = 0;		/* failed */
346 
347 	outb(0x55, io_base + UART_SCR);
348 	/* Write arbitrary data into the scratch reg */
349 	c = inb(io_base + UART_SCR);
350 	/* If it comes back, it's OK */
351 	if (c != 0x55)
352 		ok = 0;		/* failed */
353 
354 	return ok;
355 }
356 
357 static void snd_uart16550_do_open(struct snd_uart16550 * uart)
358 {
359 	char byte;
360 
361 	/* Initialize basic variables */
362 	uart->buff_in_count = 0;
363 	uart->buff_in = 0;
364 	uart->buff_out = 0;
365 	uart->fifo_limit = 1;
366 	uart->fifo_count = 0;
367 	uart->timer_running = 0;
368 
369 	outb(UART_FCR_ENABLE_FIFO	/* Enable FIFO's (if available) */
370 	     | UART_FCR_CLEAR_RCVR	/* Clear receiver FIFO */
371 	     | UART_FCR_CLEAR_XMIT	/* Clear transmitter FIFO */
372 	     | UART_FCR_TRIGGER_4	/* Set FIFO trigger at 4-bytes */
373 	/* NOTE: interrupt generated after T=(time)4-bytes
374 	 * if less than UART_FCR_TRIGGER bytes received
375 	 */
376 	     ,uart->base + UART_FCR);	/* FIFO Control Register */
377 
378 	if ((inb(uart->base + UART_IIR) & 0xf0) == 0xc0)
379 		uart->fifo_limit = 16;
380 	if (uart->divisor != 0) {
381 		uart->old_line_ctrl_reg = inb(uart->base + UART_LCR);
382 		outb(UART_LCR_DLAB	/* Divisor latch access bit */
383 		     ,uart->base + UART_LCR);	/* Line Control Register */
384 		uart->old_divisor_lsb = inb(uart->base + UART_DLL);
385 		uart->old_divisor_msb = inb(uart->base + UART_DLM);
386 
387 		outb(uart->divisor
388 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
389 		outb(0
390 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
391 		/* DLAB is reset to 0 in next outb() */
392 	}
393 	/* Set serial parameters (parity off, etc) */
394 	outb(UART_LCR_WLEN8	/* 8 data-bits */
395 	     | 0		/* 1 stop-bit */
396 	     | 0		/* parity off */
397 	     | 0		/* DLAB = 0 */
398 	     ,uart->base + UART_LCR);	/* Line Control Register */
399 
400 	switch (uart->adaptor) {
401 	default:
402 		outb(UART_MCR_RTS	/* Set Request-To-Send line active */
403 		     | UART_MCR_DTR	/* Set Data-Terminal-Ready line active */
404 		     | UART_MCR_OUT2	/* Set OUT2 - not always required, but when
405 					 * it is, it is ESSENTIAL for enabling interrupts
406 				 */
407 		     ,uart->base + UART_MCR);	/* Modem Control Register */
408 		break;
409 	case SNDRV_SERIAL_MS124W_SA:
410 	case SNDRV_SERIAL_MS124W_MB:
411 		/* MS-124W can draw power from RTS and DTR if they
412 		   are in opposite states. */
413 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | UART_MCR_OUT2,
414 		     uart->base + UART_MCR);
415 		break;
416 	case SNDRV_SERIAL_MS124T:
417 		/* MS-124T can draw power from RTS and/or DTR (preferably
418 		   both) if they are both asserted. */
419 		outb(UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2,
420 		     uart->base + UART_MCR);
421 		break;
422 	}
423 
424 	if (uart->irq < 0) {
425 		byte = (0 & UART_IER_RDI)	/* Disable Receiver data interrupt */
426 		    |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
427 		    ;
428 	} else if (uart->adaptor == SNDRV_SERIAL_MS124W_SA) {
429 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
430 		    | UART_IER_MSI	/* Enable Modem status interrupt */
431 		    ;
432 	} else if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
433 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
434 		    | UART_IER_MSI	/* Enable Modem status interrupt */
435 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
436 		    ;
437 	} else {
438 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
439 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
440 		    ;
441 	}
442 	outb(byte, uart->base + UART_IER);	/* Interrupt enable Register */
443 
444 	inb(uart->base + UART_LSR);	/* Clear any pre-existing overrun indication */
445 	inb(uart->base + UART_IIR);	/* Clear any pre-existing transmit interrupt */
446 	inb(uart->base + UART_RX);	/* Clear any pre-existing receive interrupt */
447 }
448 
449 static void snd_uart16550_do_close(struct snd_uart16550 * uart)
450 {
451 	if (uart->irq < 0)
452 		snd_uart16550_del_timer(uart);
453 
454 	/* NOTE: may need to disable interrupts before de-registering out handler.
455 	 * For now, the consequences are harmless.
456 	 */
457 
458 	outb((0 & UART_IER_RDI)		/* Disable Receiver data interrupt */
459 	     |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
460 	     ,uart->base + UART_IER);	/* Interrupt enable Register */
461 
462 	switch (uart->adaptor) {
463 	default:
464 		outb((0 & UART_MCR_RTS)		/* Deactivate Request-To-Send line  */
465 		     |(0 & UART_MCR_DTR)	/* Deactivate Data-Terminal-Ready line */
466 		     |(0 & UART_MCR_OUT2)	/* Deactivate OUT2 */
467 		     ,uart->base + UART_MCR);	/* Modem Control Register */
468 	  break;
469 	case SNDRV_SERIAL_MS124W_SA:
470 	case SNDRV_SERIAL_MS124W_MB:
471 		/* MS-124W can draw power from RTS and DTR if they
472 		   are in opposite states; leave it powered. */
473 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | (0&UART_MCR_OUT2),
474 		     uart->base + UART_MCR);
475 		break;
476 	case SNDRV_SERIAL_MS124T:
477 		/* MS-124T can draw power from RTS and/or DTR (preferably
478 		   both) if they are both asserted; leave it powered. */
479 		outb(UART_MCR_RTS | UART_MCR_DTR | (0&UART_MCR_OUT2),
480 		     uart->base + UART_MCR);
481 		break;
482 	}
483 
484 	inb(uart->base + UART_IIR);	/* Clear any outstanding interrupts */
485 
486 	/* Restore old divisor */
487 	if (uart->divisor != 0) {
488 		outb(UART_LCR_DLAB		/* Divisor latch access bit */
489 		     ,uart->base + UART_LCR);	/* Line Control Register */
490 		outb(uart->old_divisor_lsb
491 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
492 		outb(uart->old_divisor_msb
493 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
494 		/* Restore old LCR (data bits, stop bits, parity, DLAB) */
495 		outb(uart->old_line_ctrl_reg
496 		     ,uart->base + UART_LCR);	/* Line Control Register */
497 	}
498 }
499 
500 static int snd_uart16550_input_open(struct snd_rawmidi_substream *substream)
501 {
502 	unsigned long flags;
503 	struct snd_uart16550 *uart = substream->rmidi->private_data;
504 
505 	spin_lock_irqsave(&uart->open_lock, flags);
506 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
507 		snd_uart16550_do_open(uart);
508 	uart->filemode |= SERIAL_MODE_INPUT_OPEN;
509 	uart->midi_input[substream->number] = substream;
510 	spin_unlock_irqrestore(&uart->open_lock, flags);
511 	return 0;
512 }
513 
514 static int snd_uart16550_input_close(struct snd_rawmidi_substream *substream)
515 {
516 	unsigned long flags;
517 	struct snd_uart16550 *uart = substream->rmidi->private_data;
518 
519 	spin_lock_irqsave(&uart->open_lock, flags);
520 	uart->filemode &= ~SERIAL_MODE_INPUT_OPEN;
521 	uart->midi_input[substream->number] = NULL;
522 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
523 		snd_uart16550_do_close(uart);
524 	spin_unlock_irqrestore(&uart->open_lock, flags);
525 	return 0;
526 }
527 
528 static void snd_uart16550_input_trigger(struct snd_rawmidi_substream *substream,
529 					int up)
530 {
531 	unsigned long flags;
532 	struct snd_uart16550 *uart = substream->rmidi->private_data;
533 
534 	spin_lock_irqsave(&uart->open_lock, flags);
535 	if (up)
536 		uart->filemode |= SERIAL_MODE_INPUT_TRIGGERED;
537 	else
538 		uart->filemode &= ~SERIAL_MODE_INPUT_TRIGGERED;
539 	spin_unlock_irqrestore(&uart->open_lock, flags);
540 }
541 
542 static int snd_uart16550_output_open(struct snd_rawmidi_substream *substream)
543 {
544 	unsigned long flags;
545 	struct snd_uart16550 *uart = substream->rmidi->private_data;
546 
547 	spin_lock_irqsave(&uart->open_lock, flags);
548 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
549 		snd_uart16550_do_open(uart);
550 	uart->filemode |= SERIAL_MODE_OUTPUT_OPEN;
551 	uart->midi_output[substream->number] = substream;
552 	spin_unlock_irqrestore(&uart->open_lock, flags);
553 	return 0;
554 };
555 
556 static int snd_uart16550_output_close(struct snd_rawmidi_substream *substream)
557 {
558 	unsigned long flags;
559 	struct snd_uart16550 *uart = substream->rmidi->private_data;
560 
561 	spin_lock_irqsave(&uart->open_lock, flags);
562 	uart->filemode &= ~SERIAL_MODE_OUTPUT_OPEN;
563 	uart->midi_output[substream->number] = NULL;
564 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
565 		snd_uart16550_do_close(uart);
566 	spin_unlock_irqrestore(&uart->open_lock, flags);
567 	return 0;
568 };
569 
570 static inline int snd_uart16550_buffer_can_write(struct snd_uart16550 *uart,
571 						 int Num)
572 {
573 	if (uart->buff_in_count + Num < TX_BUFF_SIZE)
574 		return 1;
575 	else
576 		return 0;
577 }
578 
579 static inline int snd_uart16550_write_buffer(struct snd_uart16550 *uart,
580 					     unsigned char byte)
581 {
582 	unsigned short buff_in = uart->buff_in;
583 	if (uart->buff_in_count < TX_BUFF_SIZE) {
584 		uart->tx_buff[buff_in] = byte;
585 		buff_in++;
586 		buff_in &= TX_BUFF_MASK;
587 		uart->buff_in = buff_in;
588 		uart->buff_in_count++;
589 		if (uart->irq < 0) /* polling mode */
590 			snd_uart16550_add_timer(uart);
591 		return 1;
592 	} else
593 		return 0;
594 }
595 
596 static int snd_uart16550_output_byte(struct snd_uart16550 *uart,
597 				     struct snd_rawmidi_substream *substream,
598 				     unsigned char midi_byte)
599 {
600 	if (uart->buff_in_count == 0                    /* Buffer empty? */
601 	    && ((uart->adaptor != SNDRV_SERIAL_MS124W_SA &&
602 	    uart->adaptor != SNDRV_SERIAL_GENERIC) ||
603 		(uart->fifo_count == 0                  /* FIFO empty? */
604 		 && (inb(uart->base + UART_MSR) & UART_MSR_CTS)))) { /* CTS? */
605 
606 	        /* Tx Buffer Empty - try to write immediately */
607 		if ((inb(uart->base + UART_LSR) & UART_LSR_THRE) != 0) {
608 		        /* Transmitter holding register (and Tx FIFO) empty */
609 		        uart->fifo_count = 1;
610 			outb(midi_byte, uart->base + UART_TX);
611 		} else {
612 		        if (uart->fifo_count < uart->fifo_limit) {
613 			        uart->fifo_count++;
614 				outb(midi_byte, uart->base + UART_TX);
615 			} else {
616 			        /* Cannot write (buffer empty) -
617 				 * put char in buffer */
618 				snd_uart16550_write_buffer(uart, midi_byte);
619 			}
620 		}
621 	} else {
622 		if (!snd_uart16550_write_buffer(uart, midi_byte)) {
623 			dev_warn(uart->card->dev,
624 				 "%s: Buffer overrun on device at 0x%lx\n",
625 				 uart->rmidi->name, uart->base);
626 			return 0;
627 		}
628 	}
629 
630 	return 1;
631 }
632 
633 static void snd_uart16550_output_write(struct snd_rawmidi_substream *substream)
634 {
635 	unsigned long flags;
636 	unsigned char midi_byte, addr_byte;
637 	struct snd_uart16550 *uart = substream->rmidi->private_data;
638 	char first;
639 	static unsigned long lasttime = 0;
640 
641 	/* Interrupts are disabled during the updating of the tx_buff,
642 	 * since it is 'bad' to have two processes updating the same
643 	 * variables (ie buff_in & buff_out)
644 	 */
645 
646 	spin_lock_irqsave(&uart->open_lock, flags);
647 
648 	if (uart->irq < 0)	/* polling */
649 		snd_uart16550_io_loop(uart);
650 
651 	if (uart->adaptor == SNDRV_SERIAL_MS124W_MB) {
652 		while (1) {
653 			/* buffer full? */
654 			/* in this mode we need two bytes of space */
655 			if (uart->buff_in_count > TX_BUFF_SIZE - 2)
656 				break;
657 			if (snd_rawmidi_transmit(substream, &midi_byte, 1) != 1)
658 				break;
659 #ifdef SNDRV_SERIAL_MS124W_MB_NOCOMBO
660 			/* select exactly one of the four ports */
661 			addr_byte = (1 << (substream->number + 4)) | 0x08;
662 #else
663 			/* select any combination of the four ports */
664 			addr_byte = (substream->number << 4) | 0x08;
665 			/* ...except none */
666 			if (addr_byte == 0x08)
667 				addr_byte = 0xf8;
668 #endif
669 			snd_uart16550_output_byte(uart, substream, addr_byte);
670 			/* send midi byte */
671 			snd_uart16550_output_byte(uart, substream, midi_byte);
672 		}
673 	} else {
674 		first = 0;
675 		while (snd_rawmidi_transmit_peek(substream, &midi_byte, 1) == 1) {
676 			/* Also send F5 after 3 seconds with no data
677 			 * to handle device disconnect */
678 			if (first == 0 &&
679 			    (uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS ||
680 			     uart->adaptor == SNDRV_SERIAL_GENERIC) &&
681 			    (uart->prev_out != substream->number ||
682 			     time_after(jiffies, lasttime + 3*HZ))) {
683 
684 				if (snd_uart16550_buffer_can_write(uart, 3)) {
685 					/* Roland Soundcanvas part selection */
686 					/* If this substream of the data is
687 					 * different previous substream
688 					 * in this uart, send the change part
689 					 * event
690 					 */
691 					uart->prev_out = substream->number;
692 					/* change part */
693 					snd_uart16550_output_byte(uart, substream,
694 								  0xf5);
695 					/* data */
696 					snd_uart16550_output_byte(uart, substream,
697 								  uart->prev_out + 1);
698 					/* If midi_byte is a data byte,
699 					 * send the previous status byte */
700 					if (midi_byte < 0x80 &&
701 					    uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS)
702 						snd_uart16550_output_byte(uart, substream, uart->prev_status[uart->prev_out]);
703 				} else if (!uart->drop_on_full)
704 					break;
705 
706 			}
707 
708 			/* send midi byte */
709 			if (!snd_uart16550_output_byte(uart, substream, midi_byte) &&
710 			    !uart->drop_on_full )
711 				break;
712 
713 			if (midi_byte >= 0x80 && midi_byte < 0xf0)
714 				uart->prev_status[uart->prev_out] = midi_byte;
715 			first = 1;
716 
717 			snd_rawmidi_transmit_ack( substream, 1 );
718 		}
719 		lasttime = jiffies;
720 	}
721 	spin_unlock_irqrestore(&uart->open_lock, flags);
722 }
723 
724 static void snd_uart16550_output_trigger(struct snd_rawmidi_substream *substream,
725 					 int up)
726 {
727 	unsigned long flags;
728 	struct snd_uart16550 *uart = substream->rmidi->private_data;
729 
730 	spin_lock_irqsave(&uart->open_lock, flags);
731 	if (up)
732 		uart->filemode |= SERIAL_MODE_OUTPUT_TRIGGERED;
733 	else
734 		uart->filemode &= ~SERIAL_MODE_OUTPUT_TRIGGERED;
735 	spin_unlock_irqrestore(&uart->open_lock, flags);
736 	if (up)
737 		snd_uart16550_output_write(substream);
738 }
739 
740 static const struct snd_rawmidi_ops snd_uart16550_output =
741 {
742 	.open =		snd_uart16550_output_open,
743 	.close =	snd_uart16550_output_close,
744 	.trigger =	snd_uart16550_output_trigger,
745 };
746 
747 static const struct snd_rawmidi_ops snd_uart16550_input =
748 {
749 	.open =		snd_uart16550_input_open,
750 	.close =	snd_uart16550_input_close,
751 	.trigger =	snd_uart16550_input_trigger,
752 };
753 
754 static int snd_uart16550_create(struct snd_card *card,
755 				unsigned long iobase,
756 				int irq,
757 				unsigned int speed,
758 				unsigned int base,
759 				int adaptor,
760 				int droponfull,
761 				struct snd_uart16550 **ruart)
762 {
763 	struct snd_uart16550 *uart;
764 	int err;
765 
766 
767 	uart = devm_kzalloc(card->dev, sizeof(*uart), GFP_KERNEL);
768 	if (!uart)
769 		return -ENOMEM;
770 	uart->adaptor = adaptor;
771 	uart->card = card;
772 	spin_lock_init(&uart->open_lock);
773 	uart->irq = -1;
774 	uart->base = iobase;
775 	uart->drop_on_full = droponfull;
776 
777 	err = snd_uart16550_detect(uart);
778 	if (err <= 0) {
779 		dev_err(card->dev, "no UART detected at 0x%lx\n", iobase);
780 		return -ENODEV;
781 	}
782 
783 	if (irq >= 0 && irq != SNDRV_AUTO_IRQ) {
784 		if (devm_request_irq(card->dev, irq, snd_uart16550_interrupt,
785 				     0, "Serial MIDI", uart)) {
786 			dev_warn(card->dev,
787 				 "irq %d busy. Using Polling.\n", irq);
788 		} else {
789 			uart->irq = irq;
790 		}
791 	}
792 	uart->divisor = base / speed;
793 	uart->speed = base / (unsigned int)uart->divisor;
794 	uart->speed_base = base;
795 	uart->prev_out = -1;
796 	uart->prev_in = 0;
797 	uart->rstatus = 0;
798 	memset(uart->prev_status, 0x80, sizeof(unsigned char) * SNDRV_SERIAL_MAX_OUTS);
799 	timer_setup(&uart->buffer_timer, snd_uart16550_buffer_timer, 0);
800 	uart->timer_running = 0;
801 
802 	switch (uart->adaptor) {
803 	case SNDRV_SERIAL_MS124W_SA:
804 	case SNDRV_SERIAL_MS124W_MB:
805 		/* MS-124W can draw power from RTS and DTR if they
806 		   are in opposite states. */
807 		outb(UART_MCR_RTS | (0&UART_MCR_DTR), uart->base + UART_MCR);
808 		break;
809 	case SNDRV_SERIAL_MS124T:
810 		/* MS-124T can draw power from RTS and/or DTR (preferably
811 		   both) if they are asserted. */
812 		outb(UART_MCR_RTS | UART_MCR_DTR, uart->base + UART_MCR);
813 		break;
814 	default:
815 		break;
816 	}
817 
818 	if (ruart)
819 		*ruart = uart;
820 
821 	return 0;
822 }
823 
824 static void snd_uart16550_substreams(struct snd_rawmidi_str *stream)
825 {
826 	struct snd_rawmidi_substream *substream;
827 
828 	list_for_each_entry(substream, &stream->substreams, list) {
829 		sprintf(substream->name, "Serial MIDI %d", substream->number + 1);
830 	}
831 }
832 
833 static int snd_uart16550_rmidi(struct snd_uart16550 *uart, int device,
834 			       int outs, int ins,
835 			       struct snd_rawmidi **rmidi)
836 {
837 	struct snd_rawmidi *rrawmidi;
838 	int err;
839 
840 	err = snd_rawmidi_new(uart->card, "UART Serial MIDI", device,
841 			      outs, ins, &rrawmidi);
842 	if (err < 0)
843 		return err;
844 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_INPUT,
845 			    &snd_uart16550_input);
846 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
847 			    &snd_uart16550_output);
848 	strcpy(rrawmidi->name, "Serial MIDI");
849 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT]);
850 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT]);
851 	rrawmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
852 			       SNDRV_RAWMIDI_INFO_INPUT |
853 			       SNDRV_RAWMIDI_INFO_DUPLEX;
854 	rrawmidi->private_data = uart;
855 	if (rmidi)
856 		*rmidi = rrawmidi;
857 	return 0;
858 }
859 
860 static int snd_serial_probe(struct platform_device *devptr)
861 {
862 	struct snd_card *card;
863 	struct snd_uart16550 *uart;
864 	int err;
865 	int dev = devptr->id;
866 
867 	switch (adaptor[dev]) {
868 	case SNDRV_SERIAL_SOUNDCANVAS:
869 		ins[dev] = 1;
870 		break;
871 	case SNDRV_SERIAL_MS124T:
872 	case SNDRV_SERIAL_MS124W_SA:
873 		outs[dev] = 1;
874 		ins[dev] = 1;
875 		break;
876 	case SNDRV_SERIAL_MS124W_MB:
877 		outs[dev] = 16;
878 		ins[dev] = 1;
879 		break;
880 	case SNDRV_SERIAL_GENERIC:
881 		break;
882 	default:
883 		dev_err(&devptr->dev,
884 			"Adaptor type is out of range 0-%d (%d)\n",
885 			SNDRV_SERIAL_MAX_ADAPTOR, adaptor[dev]);
886 		return -ENODEV;
887 	}
888 
889 	if (outs[dev] < 1 || outs[dev] > SNDRV_SERIAL_MAX_OUTS) {
890 		dev_err(&devptr->dev,
891 			"Count of outputs is out of range 1-%d (%d)\n",
892 			SNDRV_SERIAL_MAX_OUTS, outs[dev]);
893 		return -ENODEV;
894 	}
895 
896 	if (ins[dev] < 1 || ins[dev] > SNDRV_SERIAL_MAX_INS) {
897 		dev_err(&devptr->dev,
898 			"Count of inputs is out of range 1-%d (%d)\n",
899 			SNDRV_SERIAL_MAX_INS, ins[dev]);
900 		return -ENODEV;
901 	}
902 
903 	err  = snd_devm_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
904 				 0, &card);
905 	if (err < 0)
906 		return err;
907 
908 	strcpy(card->driver, "Serial");
909 	strcpy(card->shortname, "Serial MIDI (UART16550A)");
910 
911 	err = snd_uart16550_create(card, port[dev], irq[dev], speed[dev],
912 				   base[dev], adaptor[dev], droponfull[dev],
913 				   &uart);
914 	if (err < 0)
915 		return err;
916 
917 	err = snd_uart16550_rmidi(uart, 0, outs[dev], ins[dev], &uart->rmidi);
918 	if (err < 0)
919 		return err;
920 
921 	sprintf(card->longname, "%s [%s] at %#lx, irq %d",
922 		card->shortname,
923 		adaptor_names[uart->adaptor],
924 		uart->base,
925 		uart->irq);
926 
927 	err = snd_card_register(card);
928 	if (err < 0)
929 		return err;
930 
931 	platform_set_drvdata(devptr, card);
932 	return 0;
933 }
934 
935 #define SND_SERIAL_DRIVER	"snd_serial_u16550"
936 
937 static struct platform_driver snd_serial_driver = {
938 	.probe		= snd_serial_probe,
939 	.driver		= {
940 		.name	= SND_SERIAL_DRIVER,
941 	},
942 };
943 
944 static void snd_serial_unregister_all(void)
945 {
946 	int i;
947 
948 	for (i = 0; i < ARRAY_SIZE(devices); ++i)
949 		platform_device_unregister(devices[i]);
950 	platform_driver_unregister(&snd_serial_driver);
951 }
952 
953 static int __init alsa_card_serial_init(void)
954 {
955 	int i, cards, err;
956 
957 	err = platform_driver_register(&snd_serial_driver);
958 	if (err < 0)
959 		return err;
960 
961 	cards = 0;
962 	for (i = 0; i < SNDRV_CARDS; i++) {
963 		struct platform_device *device;
964 		if (! enable[i])
965 			continue;
966 		device = platform_device_register_simple(SND_SERIAL_DRIVER,
967 							 i, NULL, 0);
968 		if (IS_ERR(device))
969 			continue;
970 		if (!platform_get_drvdata(device)) {
971 			platform_device_unregister(device);
972 			continue;
973 		}
974 		devices[i] = device;
975 		cards++;
976 	}
977 	if (! cards) {
978 #ifdef MODULE
979 		pr_err("serial midi soundcard not found or device busy\n");
980 #endif
981 		snd_serial_unregister_all();
982 		return -ENODEV;
983 	}
984 	return 0;
985 }
986 
987 static void __exit alsa_card_serial_exit(void)
988 {
989 	snd_serial_unregister_all();
990 }
991 
992 module_init(alsa_card_serial_init)
993 module_exit(alsa_card_serial_exit)
994