xref: /openbmc/linux/sound/drivers/serial-u16550.c (revision 63705da3)
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 			snd_printk(KERN_WARNING
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 		snd_printk(KERN_ERR "u16550: can't grab port 0x%lx\n", io_base);
327 		return -EBUSY;
328 	}
329 
330 	/* uart detected unless one of the following tests should fail */
331 	ok = 1;
332 	/* 8 data-bits, 1 stop-bit, parity off, DLAB = 0 */
333 	outb(UART_LCR_WLEN8, io_base + UART_LCR); /* Line Control Register */
334 	c = inb(io_base + UART_IER);
335 	/* The top four bits of the IER should always == 0 */
336 	if ((c & 0xf0) != 0)
337 		ok = 0;		/* failed */
338 
339 	outb(0xaa, io_base + UART_SCR);
340 	/* Write arbitrary data into the scratch reg */
341 	c = inb(io_base + UART_SCR);
342 	/* If it comes back, it's OK */
343 	if (c != 0xaa)
344 		ok = 0;		/* failed */
345 
346 	outb(0x55, io_base + UART_SCR);
347 	/* Write arbitrary data into the scratch reg */
348 	c = inb(io_base + UART_SCR);
349 	/* If it comes back, it's OK */
350 	if (c != 0x55)
351 		ok = 0;		/* failed */
352 
353 	return ok;
354 }
355 
356 static void snd_uart16550_do_open(struct snd_uart16550 * uart)
357 {
358 	char byte;
359 
360 	/* Initialize basic variables */
361 	uart->buff_in_count = 0;
362 	uart->buff_in = 0;
363 	uart->buff_out = 0;
364 	uart->fifo_limit = 1;
365 	uart->fifo_count = 0;
366 	uart->timer_running = 0;
367 
368 	outb(UART_FCR_ENABLE_FIFO	/* Enable FIFO's (if available) */
369 	     | UART_FCR_CLEAR_RCVR	/* Clear receiver FIFO */
370 	     | UART_FCR_CLEAR_XMIT	/* Clear transmitter FIFO */
371 	     | UART_FCR_TRIGGER_4	/* Set FIFO trigger at 4-bytes */
372 	/* NOTE: interrupt generated after T=(time)4-bytes
373 	 * if less than UART_FCR_TRIGGER bytes received
374 	 */
375 	     ,uart->base + UART_FCR);	/* FIFO Control Register */
376 
377 	if ((inb(uart->base + UART_IIR) & 0xf0) == 0xc0)
378 		uart->fifo_limit = 16;
379 	if (uart->divisor != 0) {
380 		uart->old_line_ctrl_reg = inb(uart->base + UART_LCR);
381 		outb(UART_LCR_DLAB	/* Divisor latch access bit */
382 		     ,uart->base + UART_LCR);	/* Line Control Register */
383 		uart->old_divisor_lsb = inb(uart->base + UART_DLL);
384 		uart->old_divisor_msb = inb(uart->base + UART_DLM);
385 
386 		outb(uart->divisor
387 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
388 		outb(0
389 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
390 		/* DLAB is reset to 0 in next outb() */
391 	}
392 	/* Set serial parameters (parity off, etc) */
393 	outb(UART_LCR_WLEN8	/* 8 data-bits */
394 	     | 0		/* 1 stop-bit */
395 	     | 0		/* parity off */
396 	     | 0		/* DLAB = 0 */
397 	     ,uart->base + UART_LCR);	/* Line Control Register */
398 
399 	switch (uart->adaptor) {
400 	default:
401 		outb(UART_MCR_RTS	/* Set Request-To-Send line active */
402 		     | UART_MCR_DTR	/* Set Data-Terminal-Ready line active */
403 		     | UART_MCR_OUT2	/* Set OUT2 - not always required, but when
404 					 * it is, it is ESSENTIAL for enabling interrupts
405 				 */
406 		     ,uart->base + UART_MCR);	/* Modem Control Register */
407 		break;
408 	case SNDRV_SERIAL_MS124W_SA:
409 	case SNDRV_SERIAL_MS124W_MB:
410 		/* MS-124W can draw power from RTS and DTR if they
411 		   are in opposite states. */
412 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | UART_MCR_OUT2,
413 		     uart->base + UART_MCR);
414 		break;
415 	case SNDRV_SERIAL_MS124T:
416 		/* MS-124T can draw power from RTS and/or DTR (preferably
417 		   both) if they are both asserted. */
418 		outb(UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2,
419 		     uart->base + UART_MCR);
420 		break;
421 	}
422 
423 	if (uart->irq < 0) {
424 		byte = (0 & UART_IER_RDI)	/* Disable Receiver data interrupt */
425 		    |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
426 		    ;
427 	} else if (uart->adaptor == SNDRV_SERIAL_MS124W_SA) {
428 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
429 		    | UART_IER_MSI	/* Enable Modem status interrupt */
430 		    ;
431 	} else if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
432 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
433 		    | UART_IER_MSI	/* Enable Modem status interrupt */
434 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
435 		    ;
436 	} else {
437 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
438 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
439 		    ;
440 	}
441 	outb(byte, uart->base + UART_IER);	/* Interrupt enable Register */
442 
443 	inb(uart->base + UART_LSR);	/* Clear any pre-existing overrun indication */
444 	inb(uart->base + UART_IIR);	/* Clear any pre-existing transmit interrupt */
445 	inb(uart->base + UART_RX);	/* Clear any pre-existing receive interrupt */
446 }
447 
448 static void snd_uart16550_do_close(struct snd_uart16550 * uart)
449 {
450 	if (uart->irq < 0)
451 		snd_uart16550_del_timer(uart);
452 
453 	/* NOTE: may need to disable interrupts before de-registering out handler.
454 	 * For now, the consequences are harmless.
455 	 */
456 
457 	outb((0 & UART_IER_RDI)		/* Disable Receiver data interrupt */
458 	     |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
459 	     ,uart->base + UART_IER);	/* Interrupt enable Register */
460 
461 	switch (uart->adaptor) {
462 	default:
463 		outb((0 & UART_MCR_RTS)		/* Deactivate Request-To-Send line  */
464 		     |(0 & UART_MCR_DTR)	/* Deactivate Data-Terminal-Ready line */
465 		     |(0 & UART_MCR_OUT2)	/* Deactivate OUT2 */
466 		     ,uart->base + UART_MCR);	/* Modem Control Register */
467 	  break;
468 	case SNDRV_SERIAL_MS124W_SA:
469 	case SNDRV_SERIAL_MS124W_MB:
470 		/* MS-124W can draw power from RTS and DTR if they
471 		   are in opposite states; leave it powered. */
472 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | (0&UART_MCR_OUT2),
473 		     uart->base + UART_MCR);
474 		break;
475 	case SNDRV_SERIAL_MS124T:
476 		/* MS-124T can draw power from RTS and/or DTR (preferably
477 		   both) if they are both asserted; leave it powered. */
478 		outb(UART_MCR_RTS | UART_MCR_DTR | (0&UART_MCR_OUT2),
479 		     uart->base + UART_MCR);
480 		break;
481 	}
482 
483 	inb(uart->base + UART_IIR);	/* Clear any outstanding interrupts */
484 
485 	/* Restore old divisor */
486 	if (uart->divisor != 0) {
487 		outb(UART_LCR_DLAB		/* Divisor latch access bit */
488 		     ,uart->base + UART_LCR);	/* Line Control Register */
489 		outb(uart->old_divisor_lsb
490 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
491 		outb(uart->old_divisor_msb
492 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
493 		/* Restore old LCR (data bits, stop bits, parity, DLAB) */
494 		outb(uart->old_line_ctrl_reg
495 		     ,uart->base + UART_LCR);	/* Line Control Register */
496 	}
497 }
498 
499 static int snd_uart16550_input_open(struct snd_rawmidi_substream *substream)
500 {
501 	unsigned long flags;
502 	struct snd_uart16550 *uart = substream->rmidi->private_data;
503 
504 	spin_lock_irqsave(&uart->open_lock, flags);
505 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
506 		snd_uart16550_do_open(uart);
507 	uart->filemode |= SERIAL_MODE_INPUT_OPEN;
508 	uart->midi_input[substream->number] = substream;
509 	spin_unlock_irqrestore(&uart->open_lock, flags);
510 	return 0;
511 }
512 
513 static int snd_uart16550_input_close(struct snd_rawmidi_substream *substream)
514 {
515 	unsigned long flags;
516 	struct snd_uart16550 *uart = substream->rmidi->private_data;
517 
518 	spin_lock_irqsave(&uart->open_lock, flags);
519 	uart->filemode &= ~SERIAL_MODE_INPUT_OPEN;
520 	uart->midi_input[substream->number] = NULL;
521 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
522 		snd_uart16550_do_close(uart);
523 	spin_unlock_irqrestore(&uart->open_lock, flags);
524 	return 0;
525 }
526 
527 static void snd_uart16550_input_trigger(struct snd_rawmidi_substream *substream,
528 					int up)
529 {
530 	unsigned long flags;
531 	struct snd_uart16550 *uart = substream->rmidi->private_data;
532 
533 	spin_lock_irqsave(&uart->open_lock, flags);
534 	if (up)
535 		uart->filemode |= SERIAL_MODE_INPUT_TRIGGERED;
536 	else
537 		uart->filemode &= ~SERIAL_MODE_INPUT_TRIGGERED;
538 	spin_unlock_irqrestore(&uart->open_lock, flags);
539 }
540 
541 static int snd_uart16550_output_open(struct snd_rawmidi_substream *substream)
542 {
543 	unsigned long flags;
544 	struct snd_uart16550 *uart = substream->rmidi->private_data;
545 
546 	spin_lock_irqsave(&uart->open_lock, flags);
547 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
548 		snd_uart16550_do_open(uart);
549 	uart->filemode |= SERIAL_MODE_OUTPUT_OPEN;
550 	uart->midi_output[substream->number] = substream;
551 	spin_unlock_irqrestore(&uart->open_lock, flags);
552 	return 0;
553 };
554 
555 static int snd_uart16550_output_close(struct snd_rawmidi_substream *substream)
556 {
557 	unsigned long flags;
558 	struct snd_uart16550 *uart = substream->rmidi->private_data;
559 
560 	spin_lock_irqsave(&uart->open_lock, flags);
561 	uart->filemode &= ~SERIAL_MODE_OUTPUT_OPEN;
562 	uart->midi_output[substream->number] = NULL;
563 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
564 		snd_uart16550_do_close(uart);
565 	spin_unlock_irqrestore(&uart->open_lock, flags);
566 	return 0;
567 };
568 
569 static inline int snd_uart16550_buffer_can_write(struct snd_uart16550 *uart,
570 						 int Num)
571 {
572 	if (uart->buff_in_count + Num < TX_BUFF_SIZE)
573 		return 1;
574 	else
575 		return 0;
576 }
577 
578 static inline int snd_uart16550_write_buffer(struct snd_uart16550 *uart,
579 					     unsigned char byte)
580 {
581 	unsigned short buff_in = uart->buff_in;
582 	if (uart->buff_in_count < TX_BUFF_SIZE) {
583 		uart->tx_buff[buff_in] = byte;
584 		buff_in++;
585 		buff_in &= TX_BUFF_MASK;
586 		uart->buff_in = buff_in;
587 		uart->buff_in_count++;
588 		if (uart->irq < 0) /* polling mode */
589 			snd_uart16550_add_timer(uart);
590 		return 1;
591 	} else
592 		return 0;
593 }
594 
595 static int snd_uart16550_output_byte(struct snd_uart16550 *uart,
596 				     struct snd_rawmidi_substream *substream,
597 				     unsigned char midi_byte)
598 {
599 	if (uart->buff_in_count == 0                    /* Buffer empty? */
600 	    && ((uart->adaptor != SNDRV_SERIAL_MS124W_SA &&
601 	    uart->adaptor != SNDRV_SERIAL_GENERIC) ||
602 		(uart->fifo_count == 0                  /* FIFO empty? */
603 		 && (inb(uart->base + UART_MSR) & UART_MSR_CTS)))) { /* CTS? */
604 
605 	        /* Tx Buffer Empty - try to write immediately */
606 		if ((inb(uart->base + UART_LSR) & UART_LSR_THRE) != 0) {
607 		        /* Transmitter holding register (and Tx FIFO) empty */
608 		        uart->fifo_count = 1;
609 			outb(midi_byte, uart->base + UART_TX);
610 		} else {
611 		        if (uart->fifo_count < uart->fifo_limit) {
612 			        uart->fifo_count++;
613 				outb(midi_byte, uart->base + UART_TX);
614 			} else {
615 			        /* Cannot write (buffer empty) -
616 				 * put char in buffer */
617 				snd_uart16550_write_buffer(uart, midi_byte);
618 			}
619 		}
620 	} else {
621 		if (!snd_uart16550_write_buffer(uart, midi_byte)) {
622 			snd_printk(KERN_WARNING
623 				   "%s: Buffer overrun on device at 0x%lx\n",
624 				   uart->rmidi->name, uart->base);
625 			return 0;
626 		}
627 	}
628 
629 	return 1;
630 }
631 
632 static void snd_uart16550_output_write(struct snd_rawmidi_substream *substream)
633 {
634 	unsigned long flags;
635 	unsigned char midi_byte, addr_byte;
636 	struct snd_uart16550 *uart = substream->rmidi->private_data;
637 	char first;
638 	static unsigned long lasttime = 0;
639 
640 	/* Interrupts are disabled during the updating of the tx_buff,
641 	 * since it is 'bad' to have two processes updating the same
642 	 * variables (ie buff_in & buff_out)
643 	 */
644 
645 	spin_lock_irqsave(&uart->open_lock, flags);
646 
647 	if (uart->irq < 0)	/* polling */
648 		snd_uart16550_io_loop(uart);
649 
650 	if (uart->adaptor == SNDRV_SERIAL_MS124W_MB) {
651 		while (1) {
652 			/* buffer full? */
653 			/* in this mode we need two bytes of space */
654 			if (uart->buff_in_count > TX_BUFF_SIZE - 2)
655 				break;
656 			if (snd_rawmidi_transmit(substream, &midi_byte, 1) != 1)
657 				break;
658 #ifdef SNDRV_SERIAL_MS124W_MB_NOCOMBO
659 			/* select exactly one of the four ports */
660 			addr_byte = (1 << (substream->number + 4)) | 0x08;
661 #else
662 			/* select any combination of the four ports */
663 			addr_byte = (substream->number << 4) | 0x08;
664 			/* ...except none */
665 			if (addr_byte == 0x08)
666 				addr_byte = 0xf8;
667 #endif
668 			snd_uart16550_output_byte(uart, substream, addr_byte);
669 			/* send midi byte */
670 			snd_uart16550_output_byte(uart, substream, midi_byte);
671 		}
672 	} else {
673 		first = 0;
674 		while (snd_rawmidi_transmit_peek(substream, &midi_byte, 1) == 1) {
675 			/* Also send F5 after 3 seconds with no data
676 			 * to handle device disconnect */
677 			if (first == 0 &&
678 			    (uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS ||
679 			     uart->adaptor == SNDRV_SERIAL_GENERIC) &&
680 			    (uart->prev_out != substream->number ||
681 			     time_after(jiffies, lasttime + 3*HZ))) {
682 
683 				if (snd_uart16550_buffer_can_write(uart, 3)) {
684 					/* Roland Soundcanvas part selection */
685 					/* If this substream of the data is
686 					 * different previous substream
687 					 * in this uart, send the change part
688 					 * event
689 					 */
690 					uart->prev_out = substream->number;
691 					/* change part */
692 					snd_uart16550_output_byte(uart, substream,
693 								  0xf5);
694 					/* data */
695 					snd_uart16550_output_byte(uart, substream,
696 								  uart->prev_out + 1);
697 					/* If midi_byte is a data byte,
698 					 * send the previous status byte */
699 					if (midi_byte < 0x80 &&
700 					    uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS)
701 						snd_uart16550_output_byte(uart, substream, uart->prev_status[uart->prev_out]);
702 				} else if (!uart->drop_on_full)
703 					break;
704 
705 			}
706 
707 			/* send midi byte */
708 			if (!snd_uart16550_output_byte(uart, substream, midi_byte) &&
709 			    !uart->drop_on_full )
710 				break;
711 
712 			if (midi_byte >= 0x80 && midi_byte < 0xf0)
713 				uart->prev_status[uart->prev_out] = midi_byte;
714 			first = 1;
715 
716 			snd_rawmidi_transmit_ack( substream, 1 );
717 		}
718 		lasttime = jiffies;
719 	}
720 	spin_unlock_irqrestore(&uart->open_lock, flags);
721 }
722 
723 static void snd_uart16550_output_trigger(struct snd_rawmidi_substream *substream,
724 					 int up)
725 {
726 	unsigned long flags;
727 	struct snd_uart16550 *uart = substream->rmidi->private_data;
728 
729 	spin_lock_irqsave(&uart->open_lock, flags);
730 	if (up)
731 		uart->filemode |= SERIAL_MODE_OUTPUT_TRIGGERED;
732 	else
733 		uart->filemode &= ~SERIAL_MODE_OUTPUT_TRIGGERED;
734 	spin_unlock_irqrestore(&uart->open_lock, flags);
735 	if (up)
736 		snd_uart16550_output_write(substream);
737 }
738 
739 static const struct snd_rawmidi_ops snd_uart16550_output =
740 {
741 	.open =		snd_uart16550_output_open,
742 	.close =	snd_uart16550_output_close,
743 	.trigger =	snd_uart16550_output_trigger,
744 };
745 
746 static const struct snd_rawmidi_ops snd_uart16550_input =
747 {
748 	.open =		snd_uart16550_input_open,
749 	.close =	snd_uart16550_input_close,
750 	.trigger =	snd_uart16550_input_trigger,
751 };
752 
753 static int snd_uart16550_create(struct snd_card *card,
754 				unsigned long iobase,
755 				int irq,
756 				unsigned int speed,
757 				unsigned int base,
758 				int adaptor,
759 				int droponfull,
760 				struct snd_uart16550 **ruart)
761 {
762 	struct snd_uart16550 *uart;
763 	int err;
764 
765 
766 	uart = devm_kzalloc(card->dev, sizeof(*uart), GFP_KERNEL);
767 	if (!uart)
768 		return -ENOMEM;
769 	uart->adaptor = adaptor;
770 	uart->card = card;
771 	spin_lock_init(&uart->open_lock);
772 	uart->irq = -1;
773 	uart->base = iobase;
774 	uart->drop_on_full = droponfull;
775 
776 	err = snd_uart16550_detect(uart);
777 	if (err <= 0) {
778 		printk(KERN_ERR "no UART detected at 0x%lx\n", iobase);
779 		return -ENODEV;
780 	}
781 
782 	if (irq >= 0 && irq != SNDRV_AUTO_IRQ) {
783 		if (devm_request_irq(card->dev, irq, snd_uart16550_interrupt,
784 				     0, "Serial MIDI", uart)) {
785 			snd_printk(KERN_WARNING
786 				   "irq %d busy. Using Polling.\n", irq);
787 		} else {
788 			uart->irq = irq;
789 		}
790 	}
791 	uart->divisor = base / speed;
792 	uart->speed = base / (unsigned int)uart->divisor;
793 	uart->speed_base = base;
794 	uart->prev_out = -1;
795 	uart->prev_in = 0;
796 	uart->rstatus = 0;
797 	memset(uart->prev_status, 0x80, sizeof(unsigned char) * SNDRV_SERIAL_MAX_OUTS);
798 	timer_setup(&uart->buffer_timer, snd_uart16550_buffer_timer, 0);
799 	uart->timer_running = 0;
800 
801 	switch (uart->adaptor) {
802 	case SNDRV_SERIAL_MS124W_SA:
803 	case SNDRV_SERIAL_MS124W_MB:
804 		/* MS-124W can draw power from RTS and DTR if they
805 		   are in opposite states. */
806 		outb(UART_MCR_RTS | (0&UART_MCR_DTR), uart->base + UART_MCR);
807 		break;
808 	case SNDRV_SERIAL_MS124T:
809 		/* MS-124T can draw power from RTS and/or DTR (preferably
810 		   both) if they are asserted. */
811 		outb(UART_MCR_RTS | UART_MCR_DTR, uart->base + UART_MCR);
812 		break;
813 	default:
814 		break;
815 	}
816 
817 	if (ruart)
818 		*ruart = uart;
819 
820 	return 0;
821 }
822 
823 static void snd_uart16550_substreams(struct snd_rawmidi_str *stream)
824 {
825 	struct snd_rawmidi_substream *substream;
826 
827 	list_for_each_entry(substream, &stream->substreams, list) {
828 		sprintf(substream->name, "Serial MIDI %d", substream->number + 1);
829 	}
830 }
831 
832 static int snd_uart16550_rmidi(struct snd_uart16550 *uart, int device,
833 			       int outs, int ins,
834 			       struct snd_rawmidi **rmidi)
835 {
836 	struct snd_rawmidi *rrawmidi;
837 	int err;
838 
839 	err = snd_rawmidi_new(uart->card, "UART Serial MIDI", device,
840 			      outs, ins, &rrawmidi);
841 	if (err < 0)
842 		return err;
843 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_INPUT,
844 			    &snd_uart16550_input);
845 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
846 			    &snd_uart16550_output);
847 	strcpy(rrawmidi->name, "Serial MIDI");
848 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT]);
849 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT]);
850 	rrawmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
851 			       SNDRV_RAWMIDI_INFO_INPUT |
852 			       SNDRV_RAWMIDI_INFO_DUPLEX;
853 	rrawmidi->private_data = uart;
854 	if (rmidi)
855 		*rmidi = rrawmidi;
856 	return 0;
857 }
858 
859 static int snd_serial_probe(struct platform_device *devptr)
860 {
861 	struct snd_card *card;
862 	struct snd_uart16550 *uart;
863 	int err;
864 	int dev = devptr->id;
865 
866 	switch (adaptor[dev]) {
867 	case SNDRV_SERIAL_SOUNDCANVAS:
868 		ins[dev] = 1;
869 		break;
870 	case SNDRV_SERIAL_MS124T:
871 	case SNDRV_SERIAL_MS124W_SA:
872 		outs[dev] = 1;
873 		ins[dev] = 1;
874 		break;
875 	case SNDRV_SERIAL_MS124W_MB:
876 		outs[dev] = 16;
877 		ins[dev] = 1;
878 		break;
879 	case SNDRV_SERIAL_GENERIC:
880 		break;
881 	default:
882 		snd_printk(KERN_ERR
883 			   "Adaptor type is out of range 0-%d (%d)\n",
884 			   SNDRV_SERIAL_MAX_ADAPTOR, adaptor[dev]);
885 		return -ENODEV;
886 	}
887 
888 	if (outs[dev] < 1 || outs[dev] > SNDRV_SERIAL_MAX_OUTS) {
889 		snd_printk(KERN_ERR
890 			   "Count of outputs is out of range 1-%d (%d)\n",
891 			   SNDRV_SERIAL_MAX_OUTS, outs[dev]);
892 		return -ENODEV;
893 	}
894 
895 	if (ins[dev] < 1 || ins[dev] > SNDRV_SERIAL_MAX_INS) {
896 		snd_printk(KERN_ERR
897 			   "Count of inputs is out of range 1-%d (%d)\n",
898 			   SNDRV_SERIAL_MAX_INS, ins[dev]);
899 		return -ENODEV;
900 	}
901 
902 	err  = snd_devm_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
903 				 0, &card);
904 	if (err < 0)
905 		return err;
906 
907 	strcpy(card->driver, "Serial");
908 	strcpy(card->shortname, "Serial MIDI (UART16550A)");
909 
910 	err = snd_uart16550_create(card, port[dev], irq[dev], speed[dev],
911 				   base[dev], adaptor[dev], droponfull[dev],
912 				   &uart);
913 	if (err < 0)
914 		return err;
915 
916 	err = snd_uart16550_rmidi(uart, 0, outs[dev], ins[dev], &uart->rmidi);
917 	if (err < 0)
918 		return err;
919 
920 	sprintf(card->longname, "%s [%s] at %#lx, irq %d",
921 		card->shortname,
922 		adaptor_names[uart->adaptor],
923 		uart->base,
924 		uart->irq);
925 
926 	err = snd_card_register(card);
927 	if (err < 0)
928 		return err;
929 
930 	platform_set_drvdata(devptr, card);
931 	return 0;
932 }
933 
934 #define SND_SERIAL_DRIVER	"snd_serial_u16550"
935 
936 static struct platform_driver snd_serial_driver = {
937 	.probe		= snd_serial_probe,
938 	.driver		= {
939 		.name	= SND_SERIAL_DRIVER,
940 	},
941 };
942 
943 static void snd_serial_unregister_all(void)
944 {
945 	int i;
946 
947 	for (i = 0; i < ARRAY_SIZE(devices); ++i)
948 		platform_device_unregister(devices[i]);
949 	platform_driver_unregister(&snd_serial_driver);
950 }
951 
952 static int __init alsa_card_serial_init(void)
953 {
954 	int i, cards, err;
955 
956 	err = platform_driver_register(&snd_serial_driver);
957 	if (err < 0)
958 		return err;
959 
960 	cards = 0;
961 	for (i = 0; i < SNDRV_CARDS; i++) {
962 		struct platform_device *device;
963 		if (! enable[i])
964 			continue;
965 		device = platform_device_register_simple(SND_SERIAL_DRIVER,
966 							 i, NULL, 0);
967 		if (IS_ERR(device))
968 			continue;
969 		if (!platform_get_drvdata(device)) {
970 			platform_device_unregister(device);
971 			continue;
972 		}
973 		devices[i] = device;
974 		cards++;
975 	}
976 	if (! cards) {
977 #ifdef MODULE
978 		printk(KERN_ERR "serial midi soundcard not found or device busy\n");
979 #endif
980 		snd_serial_unregister_all();
981 		return -ENODEV;
982 	}
983 	return 0;
984 }
985 
986 static void __exit alsa_card_serial_exit(void)
987 {
988 	snd_serial_unregister_all();
989 }
990 
991 module_init(alsa_card_serial_init)
992 module_exit(alsa_card_serial_exit)
993