xref: /openbmc/linux/sound/drivers/serial-u16550.c (revision 842ed298)
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 MODULE_SUPPORTED_DEVICE("{{ALSA, MIDI serial u16550}}");
38 
39 #define SNDRV_SERIAL_SOUNDCANVAS 0 /* Roland Soundcanvas; F5 NN selects part */
40 #define SNDRV_SERIAL_MS124T 1      /* Midiator MS-124T */
41 #define SNDRV_SERIAL_MS124W_SA 2   /* Midiator MS-124W in S/A mode */
42 #define SNDRV_SERIAL_MS124W_MB 3   /* Midiator MS-124W in M/B mode */
43 #define SNDRV_SERIAL_GENERIC 4     /* Generic Interface */
44 #define SNDRV_SERIAL_MAX_ADAPTOR SNDRV_SERIAL_GENERIC
45 static const char * const adaptor_names[] = {
46 	"Soundcanvas",
47         "MS-124T",
48 	"MS-124W S/A",
49 	"MS-124W M/B",
50 	"Generic"
51 };
52 
53 #define SNDRV_SERIAL_NORMALBUFF 0 /* Normal blocking buffer operation */
54 #define SNDRV_SERIAL_DROPBUFF   1 /* Non-blocking discard operation */
55 
56 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
57 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
58 static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE; /* Enable this card */
59 static long port[SNDRV_CARDS] = SNDRV_DEFAULT_PORT; /* 0x3f8,0x2f8,0x3e8,0x2e8 */
60 static int irq[SNDRV_CARDS] = SNDRV_DEFAULT_IRQ; 	/* 3,4,5,7,9,10,11,14,15 */
61 static int speed[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 38400}; /* 9600,19200,38400,57600,115200 */
62 static int base[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 115200}; /* baud base */
63 static int outs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};	 /* 1 to 16 */
64 static int ins[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};	/* 1 to 16 */
65 static int adaptor[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = SNDRV_SERIAL_SOUNDCANVAS};
66 static bool droponfull[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS -1)] = SNDRV_SERIAL_NORMALBUFF };
67 
68 module_param_array(index, int, NULL, 0444);
69 MODULE_PARM_DESC(index, "Index value for Serial MIDI.");
70 module_param_array(id, charp, NULL, 0444);
71 MODULE_PARM_DESC(id, "ID string for Serial MIDI.");
72 module_param_array(enable, bool, NULL, 0444);
73 MODULE_PARM_DESC(enable, "Enable UART16550A chip.");
74 module_param_hw_array(port, long, ioport, NULL, 0444);
75 MODULE_PARM_DESC(port, "Port # for UART16550A chip.");
76 module_param_hw_array(irq, int, irq, NULL, 0444);
77 MODULE_PARM_DESC(irq, "IRQ # for UART16550A chip.");
78 module_param_array(speed, int, NULL, 0444);
79 MODULE_PARM_DESC(speed, "Speed in bauds.");
80 module_param_array(base, int, NULL, 0444);
81 MODULE_PARM_DESC(base, "Base for divisor in bauds.");
82 module_param_array(outs, int, NULL, 0444);
83 MODULE_PARM_DESC(outs, "Number of MIDI outputs.");
84 module_param_array(ins, int, NULL, 0444);
85 MODULE_PARM_DESC(ins, "Number of MIDI inputs.");
86 module_param_array(droponfull, bool, NULL, 0444);
87 MODULE_PARM_DESC(droponfull, "Flag to enable drop-on-full buffer mode");
88 
89 module_param_array(adaptor, int, NULL, 0444);
90 MODULE_PARM_DESC(adaptor, "Type of adaptor.");
91 
92 /*#define SNDRV_SERIAL_MS124W_MB_NOCOMBO 1*/  /* Address outs as 0-3 instead of bitmap */
93 
94 #define SNDRV_SERIAL_MAX_OUTS	16		/* max 64, min 16 */
95 #define SNDRV_SERIAL_MAX_INS	16		/* max 64, min 16 */
96 
97 #define TX_BUFF_SIZE		(1<<15)		/* Must be 2^n */
98 #define TX_BUFF_MASK		(TX_BUFF_SIZE - 1)
99 
100 #define SERIAL_MODE_NOT_OPENED 		(0)
101 #define SERIAL_MODE_INPUT_OPEN		(1 << 0)
102 #define SERIAL_MODE_OUTPUT_OPEN		(1 << 1)
103 #define SERIAL_MODE_INPUT_TRIGGERED	(1 << 2)
104 #define SERIAL_MODE_OUTPUT_TRIGGERED	(1 << 3)
105 
106 struct snd_uart16550 {
107 	struct snd_card *card;
108 	struct snd_rawmidi *rmidi;
109 	struct snd_rawmidi_substream *midi_output[SNDRV_SERIAL_MAX_OUTS];
110 	struct snd_rawmidi_substream *midi_input[SNDRV_SERIAL_MAX_INS];
111 
112 	int filemode;		/* open status of file */
113 
114 	spinlock_t open_lock;
115 
116 	int irq;
117 
118 	unsigned long base;
119 	struct resource *res_base;
120 
121 	unsigned int speed;
122 	unsigned int speed_base;
123 	unsigned char divisor;
124 
125 	unsigned char old_divisor_lsb;
126 	unsigned char old_divisor_msb;
127 	unsigned char old_line_ctrl_reg;
128 
129 	/* parameter for using of write loop */
130 	short int fifo_limit;	/* used in uart16550 */
131         short int fifo_count;	/* used in uart16550 */
132 
133 	/* type of adaptor */
134 	int adaptor;
135 
136 	/* inputs */
137 	int prev_in;
138 	unsigned char rstatus;
139 
140 	/* outputs */
141 	int prev_out;
142 	unsigned char prev_status[SNDRV_SERIAL_MAX_OUTS];
143 
144 	/* write buffer and its writing/reading position */
145 	unsigned char tx_buff[TX_BUFF_SIZE];
146 	int buff_in_count;
147         int buff_in;
148         int buff_out;
149         int drop_on_full;
150 
151 	/* wait timer */
152 	unsigned int timer_running:1;
153 	struct timer_list buffer_timer;
154 
155 };
156 
157 static struct platform_device *devices[SNDRV_CARDS];
158 
159 static inline void snd_uart16550_add_timer(struct snd_uart16550 *uart)
160 {
161 	if (!uart->timer_running) {
162 		/* timer 38600bps * 10bit * 16byte */
163 		mod_timer(&uart->buffer_timer, jiffies + (HZ + 255) / 256);
164 		uart->timer_running = 1;
165 	}
166 }
167 
168 static inline void snd_uart16550_del_timer(struct snd_uart16550 *uart)
169 {
170 	if (uart->timer_running) {
171 		del_timer(&uart->buffer_timer);
172 		uart->timer_running = 0;
173 	}
174 }
175 
176 /* This macro is only used in snd_uart16550_io_loop */
177 static inline void snd_uart16550_buffer_output(struct snd_uart16550 *uart)
178 {
179 	unsigned short buff_out = uart->buff_out;
180 	if (uart->buff_in_count > 0) {
181 		outb(uart->tx_buff[buff_out], uart->base + UART_TX);
182 		uart->fifo_count++;
183 		buff_out++;
184 		buff_out &= TX_BUFF_MASK;
185 		uart->buff_out = buff_out;
186 		uart->buff_in_count--;
187 	}
188 }
189 
190 /* This loop should be called with interrupts disabled
191  * We don't want to interrupt this,
192  * as we're already handling an interrupt
193  */
194 static void snd_uart16550_io_loop(struct snd_uart16550 * uart)
195 {
196 	unsigned char c, status;
197 	int substream;
198 
199 	/* recall previous stream */
200 	substream = uart->prev_in;
201 
202 	/* Read Loop */
203 	while ((status = inb(uart->base + UART_LSR)) & UART_LSR_DR) {
204 		/* while receive data ready */
205 		c = inb(uart->base + UART_RX);
206 
207 		/* keep track of last status byte */
208 		if (c & 0x80)
209 			uart->rstatus = c;
210 
211 		/* handle stream switch */
212 		if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
213 			if (uart->rstatus == 0xf5) {
214 				if (c <= SNDRV_SERIAL_MAX_INS && c > 0)
215 					substream = c - 1;
216 				if (c != 0xf5)
217 					/* prevent future bytes from being
218 					   interpreted as streams */
219 					uart->rstatus = 0;
220 			} else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN)
221 				   && uart->midi_input[substream])
222 				snd_rawmidi_receive(uart->midi_input[substream],
223 						    &c, 1);
224 		} else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN) &&
225 			   uart->midi_input[substream])
226 			snd_rawmidi_receive(uart->midi_input[substream], &c, 1);
227 
228 		if (status & UART_LSR_OE)
229 			snd_printk(KERN_WARNING
230 				   "%s: Overrun on device at 0x%lx\n",
231 			       uart->rmidi->name, uart->base);
232 	}
233 
234 	/* remember the last stream */
235 	uart->prev_in = substream;
236 
237 	/* no need of check SERIAL_MODE_OUTPUT_OPEN because if not,
238 	   buffer is never filled. */
239 	/* Check write status */
240 	if (status & UART_LSR_THRE)
241 		uart->fifo_count = 0;
242 	if (uart->adaptor == SNDRV_SERIAL_MS124W_SA
243 	   || uart->adaptor == SNDRV_SERIAL_GENERIC) {
244 		/* Can't use FIFO, must send only when CTS is true */
245 		status = inb(uart->base + UART_MSR);
246 		while (uart->fifo_count == 0 && (status & UART_MSR_CTS) &&
247 		       uart->buff_in_count > 0) {
248 		       snd_uart16550_buffer_output(uart);
249 		       status = inb(uart->base + UART_MSR);
250 		}
251 	} else {
252 		/* Write loop */
253 		while (uart->fifo_count < uart->fifo_limit /* Can we write ? */
254 		       && uart->buff_in_count > 0)	/* Do we want to? */
255 			snd_uart16550_buffer_output(uart);
256 	}
257 	if (uart->irq < 0 && uart->buff_in_count > 0)
258 		snd_uart16550_add_timer(uart);
259 }
260 
261 /* NOTES ON SERVICING INTERUPTS
262  * ---------------------------
263  * After receiving a interrupt, it is important to indicate to the UART that
264  * this has been done.
265  * For a Rx interrupt, this is done by reading the received byte.
266  * For a Tx interrupt this is done by either:
267  * a) Writing a byte
268  * b) Reading the IIR
269  * It is particularly important to read the IIR if a Tx interrupt is received
270  * when there is no data in tx_buff[], as in this case there no other
271  * indication that the interrupt has been serviced, and it remains outstanding
272  * indefinitely. This has the curious side effect that and no further interrupts
273  * will be generated from this device AT ALL!!.
274  * It is also desirable to clear outstanding interrupts when the device is
275  * opened/closed.
276  *
277  *
278  * Note that some devices need OUT2 to be set before they will generate
279  * interrupts at all. (Possibly tied to an internal pull-up on CTS?)
280  */
281 static irqreturn_t snd_uart16550_interrupt(int irq, void *dev_id)
282 {
283 	struct snd_uart16550 *uart;
284 
285 	uart = dev_id;
286 	spin_lock(&uart->open_lock);
287 	if (uart->filemode == SERIAL_MODE_NOT_OPENED) {
288 		spin_unlock(&uart->open_lock);
289 		return IRQ_NONE;
290 	}
291 	/* indicate to the UART that the interrupt has been serviced */
292 	inb(uart->base + UART_IIR);
293 	snd_uart16550_io_loop(uart);
294 	spin_unlock(&uart->open_lock);
295 	return IRQ_HANDLED;
296 }
297 
298 /* When the polling mode, this function calls snd_uart16550_io_loop. */
299 static void snd_uart16550_buffer_timer(struct timer_list *t)
300 {
301 	unsigned long flags;
302 	struct snd_uart16550 *uart;
303 
304 	uart = from_timer(uart, t, buffer_timer);
305 	spin_lock_irqsave(&uart->open_lock, flags);
306 	snd_uart16550_del_timer(uart);
307 	snd_uart16550_io_loop(uart);
308 	spin_unlock_irqrestore(&uart->open_lock, flags);
309 }
310 
311 /*
312  *  this method probes, if an uart sits on given port
313  *  return 0 if found
314  *  return negative error if not found
315  */
316 static int snd_uart16550_detect(struct snd_uart16550 *uart)
317 {
318 	unsigned long io_base = uart->base;
319 	int ok;
320 	unsigned char c;
321 
322 	/* Do some vague tests for the presence of the uart */
323 	if (io_base == 0 || io_base == SNDRV_AUTO_PORT) {
324 		return -ENODEV;	/* Not configured */
325 	}
326 
327 	uart->res_base = request_region(io_base, 8, "Serial MIDI");
328 	if (uart->res_base == NULL) {
329 		snd_printk(KERN_ERR "u16550: can't grab port 0x%lx\n", io_base);
330 		return -EBUSY;
331 	}
332 
333 	/* uart detected unless one of the following tests should fail */
334 	ok = 1;
335 	/* 8 data-bits, 1 stop-bit, parity off, DLAB = 0 */
336 	outb(UART_LCR_WLEN8, io_base + UART_LCR); /* Line Control Register */
337 	c = inb(io_base + UART_IER);
338 	/* The top four bits of the IER should always == 0 */
339 	if ((c & 0xf0) != 0)
340 		ok = 0;		/* failed */
341 
342 	outb(0xaa, io_base + UART_SCR);
343 	/* Write arbitrary data into the scratch reg */
344 	c = inb(io_base + UART_SCR);
345 	/* If it comes back, it's OK */
346 	if (c != 0xaa)
347 		ok = 0;		/* failed */
348 
349 	outb(0x55, io_base + UART_SCR);
350 	/* Write arbitrary data into the scratch reg */
351 	c = inb(io_base + UART_SCR);
352 	/* If it comes back, it's OK */
353 	if (c != 0x55)
354 		ok = 0;		/* failed */
355 
356 	return ok;
357 }
358 
359 static void snd_uart16550_do_open(struct snd_uart16550 * uart)
360 {
361 	char byte;
362 
363 	/* Initialize basic variables */
364 	uart->buff_in_count = 0;
365 	uart->buff_in = 0;
366 	uart->buff_out = 0;
367 	uart->fifo_limit = 1;
368 	uart->fifo_count = 0;
369 	uart->timer_running = 0;
370 
371 	outb(UART_FCR_ENABLE_FIFO	/* Enable FIFO's (if available) */
372 	     | UART_FCR_CLEAR_RCVR	/* Clear receiver FIFO */
373 	     | UART_FCR_CLEAR_XMIT	/* Clear transmitter FIFO */
374 	     | UART_FCR_TRIGGER_4	/* Set FIFO trigger at 4-bytes */
375 	/* NOTE: interrupt generated after T=(time)4-bytes
376 	 * if less than UART_FCR_TRIGGER bytes received
377 	 */
378 	     ,uart->base + UART_FCR);	/* FIFO Control Register */
379 
380 	if ((inb(uart->base + UART_IIR) & 0xf0) == 0xc0)
381 		uart->fifo_limit = 16;
382 	if (uart->divisor != 0) {
383 		uart->old_line_ctrl_reg = inb(uart->base + UART_LCR);
384 		outb(UART_LCR_DLAB	/* Divisor latch access bit */
385 		     ,uart->base + UART_LCR);	/* Line Control Register */
386 		uart->old_divisor_lsb = inb(uart->base + UART_DLL);
387 		uart->old_divisor_msb = inb(uart->base + UART_DLM);
388 
389 		outb(uart->divisor
390 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
391 		outb(0
392 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
393 		/* DLAB is reset to 0 in next outb() */
394 	}
395 	/* Set serial parameters (parity off, etc) */
396 	outb(UART_LCR_WLEN8	/* 8 data-bits */
397 	     | 0		/* 1 stop-bit */
398 	     | 0		/* parity off */
399 	     | 0		/* DLAB = 0 */
400 	     ,uart->base + UART_LCR);	/* Line Control Register */
401 
402 	switch (uart->adaptor) {
403 	default:
404 		outb(UART_MCR_RTS	/* Set Request-To-Send line active */
405 		     | UART_MCR_DTR	/* Set Data-Terminal-Ready line active */
406 		     | UART_MCR_OUT2	/* Set OUT2 - not always required, but when
407 					 * it is, it is ESSENTIAL for enabling interrupts
408 				 */
409 		     ,uart->base + UART_MCR);	/* Modem Control Register */
410 		break;
411 	case SNDRV_SERIAL_MS124W_SA:
412 	case SNDRV_SERIAL_MS124W_MB:
413 		/* MS-124W can draw power from RTS and DTR if they
414 		   are in opposite states. */
415 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | UART_MCR_OUT2,
416 		     uart->base + UART_MCR);
417 		break;
418 	case SNDRV_SERIAL_MS124T:
419 		/* MS-124T can draw power from RTS and/or DTR (preferably
420 		   both) if they are both asserted. */
421 		outb(UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2,
422 		     uart->base + UART_MCR);
423 		break;
424 	}
425 
426 	if (uart->irq < 0) {
427 		byte = (0 & UART_IER_RDI)	/* Disable Receiver data interrupt */
428 		    |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
429 		    ;
430 	} else if (uart->adaptor == SNDRV_SERIAL_MS124W_SA) {
431 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
432 		    | UART_IER_MSI	/* Enable Modem status interrupt */
433 		    ;
434 	} else if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
435 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
436 		    | UART_IER_MSI	/* Enable Modem status interrupt */
437 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
438 		    ;
439 	} else {
440 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
441 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
442 		    ;
443 	}
444 	outb(byte, uart->base + UART_IER);	/* Interrupt enable Register */
445 
446 	inb(uart->base + UART_LSR);	/* Clear any pre-existing overrun indication */
447 	inb(uart->base + UART_IIR);	/* Clear any pre-existing transmit interrupt */
448 	inb(uart->base + UART_RX);	/* Clear any pre-existing receive interrupt */
449 }
450 
451 static void snd_uart16550_do_close(struct snd_uart16550 * uart)
452 {
453 	if (uart->irq < 0)
454 		snd_uart16550_del_timer(uart);
455 
456 	/* NOTE: may need to disable interrupts before de-registering out handler.
457 	 * For now, the consequences are harmless.
458 	 */
459 
460 	outb((0 & UART_IER_RDI)		/* Disable Receiver data interrupt */
461 	     |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
462 	     ,uart->base + UART_IER);	/* Interrupt enable Register */
463 
464 	switch (uart->adaptor) {
465 	default:
466 		outb((0 & UART_MCR_RTS)		/* Deactivate Request-To-Send line  */
467 		     |(0 & UART_MCR_DTR)	/* Deactivate Data-Terminal-Ready line */
468 		     |(0 & UART_MCR_OUT2)	/* Deactivate OUT2 */
469 		     ,uart->base + UART_MCR);	/* Modem Control Register */
470 	  break;
471 	case SNDRV_SERIAL_MS124W_SA:
472 	case SNDRV_SERIAL_MS124W_MB:
473 		/* MS-124W can draw power from RTS and DTR if they
474 		   are in opposite states; leave it powered. */
475 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | (0&UART_MCR_OUT2),
476 		     uart->base + UART_MCR);
477 		break;
478 	case SNDRV_SERIAL_MS124T:
479 		/* MS-124T can draw power from RTS and/or DTR (preferably
480 		   both) if they are both asserted; leave it powered. */
481 		outb(UART_MCR_RTS | UART_MCR_DTR | (0&UART_MCR_OUT2),
482 		     uart->base + UART_MCR);
483 		break;
484 	}
485 
486 	inb(uart->base + UART_IIR);	/* Clear any outstanding interrupts */
487 
488 	/* Restore old divisor */
489 	if (uart->divisor != 0) {
490 		outb(UART_LCR_DLAB		/* Divisor latch access bit */
491 		     ,uart->base + UART_LCR);	/* Line Control Register */
492 		outb(uart->old_divisor_lsb
493 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
494 		outb(uart->old_divisor_msb
495 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
496 		/* Restore old LCR (data bits, stop bits, parity, DLAB) */
497 		outb(uart->old_line_ctrl_reg
498 		     ,uart->base + UART_LCR);	/* Line Control Register */
499 	}
500 }
501 
502 static int snd_uart16550_input_open(struct snd_rawmidi_substream *substream)
503 {
504 	unsigned long flags;
505 	struct snd_uart16550 *uart = substream->rmidi->private_data;
506 
507 	spin_lock_irqsave(&uart->open_lock, flags);
508 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
509 		snd_uart16550_do_open(uart);
510 	uart->filemode |= SERIAL_MODE_INPUT_OPEN;
511 	uart->midi_input[substream->number] = substream;
512 	spin_unlock_irqrestore(&uart->open_lock, flags);
513 	return 0;
514 }
515 
516 static int snd_uart16550_input_close(struct snd_rawmidi_substream *substream)
517 {
518 	unsigned long flags;
519 	struct snd_uart16550 *uart = substream->rmidi->private_data;
520 
521 	spin_lock_irqsave(&uart->open_lock, flags);
522 	uart->filemode &= ~SERIAL_MODE_INPUT_OPEN;
523 	uart->midi_input[substream->number] = NULL;
524 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
525 		snd_uart16550_do_close(uart);
526 	spin_unlock_irqrestore(&uart->open_lock, flags);
527 	return 0;
528 }
529 
530 static void snd_uart16550_input_trigger(struct snd_rawmidi_substream *substream,
531 					int up)
532 {
533 	unsigned long flags;
534 	struct snd_uart16550 *uart = substream->rmidi->private_data;
535 
536 	spin_lock_irqsave(&uart->open_lock, flags);
537 	if (up)
538 		uart->filemode |= SERIAL_MODE_INPUT_TRIGGERED;
539 	else
540 		uart->filemode &= ~SERIAL_MODE_INPUT_TRIGGERED;
541 	spin_unlock_irqrestore(&uart->open_lock, flags);
542 }
543 
544 static int snd_uart16550_output_open(struct snd_rawmidi_substream *substream)
545 {
546 	unsigned long flags;
547 	struct snd_uart16550 *uart = substream->rmidi->private_data;
548 
549 	spin_lock_irqsave(&uart->open_lock, flags);
550 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
551 		snd_uart16550_do_open(uart);
552 	uart->filemode |= SERIAL_MODE_OUTPUT_OPEN;
553 	uart->midi_output[substream->number] = substream;
554 	spin_unlock_irqrestore(&uart->open_lock, flags);
555 	return 0;
556 };
557 
558 static int snd_uart16550_output_close(struct snd_rawmidi_substream *substream)
559 {
560 	unsigned long flags;
561 	struct snd_uart16550 *uart = substream->rmidi->private_data;
562 
563 	spin_lock_irqsave(&uart->open_lock, flags);
564 	uart->filemode &= ~SERIAL_MODE_OUTPUT_OPEN;
565 	uart->midi_output[substream->number] = NULL;
566 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
567 		snd_uart16550_do_close(uart);
568 	spin_unlock_irqrestore(&uart->open_lock, flags);
569 	return 0;
570 };
571 
572 static inline int snd_uart16550_buffer_can_write(struct snd_uart16550 *uart,
573 						 int Num)
574 {
575 	if (uart->buff_in_count + Num < TX_BUFF_SIZE)
576 		return 1;
577 	else
578 		return 0;
579 }
580 
581 static inline int snd_uart16550_write_buffer(struct snd_uart16550 *uart,
582 					     unsigned char byte)
583 {
584 	unsigned short buff_in = uart->buff_in;
585 	if (uart->buff_in_count < TX_BUFF_SIZE) {
586 		uart->tx_buff[buff_in] = byte;
587 		buff_in++;
588 		buff_in &= TX_BUFF_MASK;
589 		uart->buff_in = buff_in;
590 		uart->buff_in_count++;
591 		if (uart->irq < 0) /* polling mode */
592 			snd_uart16550_add_timer(uart);
593 		return 1;
594 	} else
595 		return 0;
596 }
597 
598 static int snd_uart16550_output_byte(struct snd_uart16550 *uart,
599 				     struct snd_rawmidi_substream *substream,
600 				     unsigned char midi_byte)
601 {
602 	if (uart->buff_in_count == 0                    /* Buffer empty? */
603 	    && ((uart->adaptor != SNDRV_SERIAL_MS124W_SA &&
604 	    uart->adaptor != SNDRV_SERIAL_GENERIC) ||
605 		(uart->fifo_count == 0                  /* FIFO empty? */
606 		 && (inb(uart->base + UART_MSR) & UART_MSR_CTS)))) { /* CTS? */
607 
608 	        /* Tx Buffer Empty - try to write immediately */
609 		if ((inb(uart->base + UART_LSR) & UART_LSR_THRE) != 0) {
610 		        /* Transmitter holding register (and Tx FIFO) empty */
611 		        uart->fifo_count = 1;
612 			outb(midi_byte, uart->base + UART_TX);
613 		} else {
614 		        if (uart->fifo_count < uart->fifo_limit) {
615 			        uart->fifo_count++;
616 				outb(midi_byte, uart->base + UART_TX);
617 			} else {
618 			        /* Cannot write (buffer empty) -
619 				 * put char in buffer */
620 				snd_uart16550_write_buffer(uart, midi_byte);
621 			}
622 		}
623 	} else {
624 		if (!snd_uart16550_write_buffer(uart, midi_byte)) {
625 			snd_printk(KERN_WARNING
626 				   "%s: Buffer overrun on device at 0x%lx\n",
627 				   uart->rmidi->name, uart->base);
628 			return 0;
629 		}
630 	}
631 
632 	return 1;
633 }
634 
635 static void snd_uart16550_output_write(struct snd_rawmidi_substream *substream)
636 {
637 	unsigned long flags;
638 	unsigned char midi_byte, addr_byte;
639 	struct snd_uart16550 *uart = substream->rmidi->private_data;
640 	char first;
641 	static unsigned long lasttime = 0;
642 
643 	/* Interrupts are disabled during the updating of the tx_buff,
644 	 * since it is 'bad' to have two processes updating the same
645 	 * variables (ie buff_in & buff_out)
646 	 */
647 
648 	spin_lock_irqsave(&uart->open_lock, flags);
649 
650 	if (uart->irq < 0)	/* polling */
651 		snd_uart16550_io_loop(uart);
652 
653 	if (uart->adaptor == SNDRV_SERIAL_MS124W_MB) {
654 		while (1) {
655 			/* buffer full? */
656 			/* in this mode we need two bytes of space */
657 			if (uart->buff_in_count > TX_BUFF_SIZE - 2)
658 				break;
659 			if (snd_rawmidi_transmit(substream, &midi_byte, 1) != 1)
660 				break;
661 #ifdef SNDRV_SERIAL_MS124W_MB_NOCOMBO
662 			/* select exactly one of the four ports */
663 			addr_byte = (1 << (substream->number + 4)) | 0x08;
664 #else
665 			/* select any combination of the four ports */
666 			addr_byte = (substream->number << 4) | 0x08;
667 			/* ...except none */
668 			if (addr_byte == 0x08)
669 				addr_byte = 0xf8;
670 #endif
671 			snd_uart16550_output_byte(uart, substream, addr_byte);
672 			/* send midi byte */
673 			snd_uart16550_output_byte(uart, substream, midi_byte);
674 		}
675 	} else {
676 		first = 0;
677 		while (snd_rawmidi_transmit_peek(substream, &midi_byte, 1) == 1) {
678 			/* Also send F5 after 3 seconds with no data
679 			 * to handle device disconnect */
680 			if (first == 0 &&
681 			    (uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS ||
682 			     uart->adaptor == SNDRV_SERIAL_GENERIC) &&
683 			    (uart->prev_out != substream->number ||
684 			     time_after(jiffies, lasttime + 3*HZ))) {
685 
686 				if (snd_uart16550_buffer_can_write(uart, 3)) {
687 					/* Roland Soundcanvas part selection */
688 					/* If this substream of the data is
689 					 * different previous substream
690 					 * in this uart, send the change part
691 					 * event
692 					 */
693 					uart->prev_out = substream->number;
694 					/* change part */
695 					snd_uart16550_output_byte(uart, substream,
696 								  0xf5);
697 					/* data */
698 					snd_uart16550_output_byte(uart, substream,
699 								  uart->prev_out + 1);
700 					/* If midi_byte is a data byte,
701 					 * send the previous status byte */
702 					if (midi_byte < 0x80 &&
703 					    uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS)
704 						snd_uart16550_output_byte(uart, substream, uart->prev_status[uart->prev_out]);
705 				} else if (!uart->drop_on_full)
706 					break;
707 
708 			}
709 
710 			/* send midi byte */
711 			if (!snd_uart16550_output_byte(uart, substream, midi_byte) &&
712 			    !uart->drop_on_full )
713 				break;
714 
715 			if (midi_byte >= 0x80 && midi_byte < 0xf0)
716 				uart->prev_status[uart->prev_out] = midi_byte;
717 			first = 1;
718 
719 			snd_rawmidi_transmit_ack( substream, 1 );
720 		}
721 		lasttime = jiffies;
722 	}
723 	spin_unlock_irqrestore(&uart->open_lock, flags);
724 }
725 
726 static void snd_uart16550_output_trigger(struct snd_rawmidi_substream *substream,
727 					 int up)
728 {
729 	unsigned long flags;
730 	struct snd_uart16550 *uart = substream->rmidi->private_data;
731 
732 	spin_lock_irqsave(&uart->open_lock, flags);
733 	if (up)
734 		uart->filemode |= SERIAL_MODE_OUTPUT_TRIGGERED;
735 	else
736 		uart->filemode &= ~SERIAL_MODE_OUTPUT_TRIGGERED;
737 	spin_unlock_irqrestore(&uart->open_lock, flags);
738 	if (up)
739 		snd_uart16550_output_write(substream);
740 }
741 
742 static const struct snd_rawmidi_ops snd_uart16550_output =
743 {
744 	.open =		snd_uart16550_output_open,
745 	.close =	snd_uart16550_output_close,
746 	.trigger =	snd_uart16550_output_trigger,
747 };
748 
749 static const struct snd_rawmidi_ops snd_uart16550_input =
750 {
751 	.open =		snd_uart16550_input_open,
752 	.close =	snd_uart16550_input_close,
753 	.trigger =	snd_uart16550_input_trigger,
754 };
755 
756 static int snd_uart16550_free(struct snd_uart16550 *uart)
757 {
758 	if (uart->irq >= 0)
759 		free_irq(uart->irq, uart);
760 	release_and_free_resource(uart->res_base);
761 	kfree(uart);
762 	return 0;
763 };
764 
765 static int snd_uart16550_dev_free(struct snd_device *device)
766 {
767 	struct snd_uart16550 *uart = device->device_data;
768 	return snd_uart16550_free(uart);
769 }
770 
771 static int snd_uart16550_create(struct snd_card *card,
772 				unsigned long iobase,
773 				int irq,
774 				unsigned int speed,
775 				unsigned int base,
776 				int adaptor,
777 				int droponfull,
778 				struct snd_uart16550 **ruart)
779 {
780 	static const struct snd_device_ops ops = {
781 		.dev_free =	snd_uart16550_dev_free,
782 	};
783 	struct snd_uart16550 *uart;
784 	int err;
785 
786 
787 	if ((uart = kzalloc(sizeof(*uart), GFP_KERNEL)) == NULL)
788 		return -ENOMEM;
789 	uart->adaptor = adaptor;
790 	uart->card = card;
791 	spin_lock_init(&uart->open_lock);
792 	uart->irq = -1;
793 	uart->base = iobase;
794 	uart->drop_on_full = droponfull;
795 
796 	if ((err = snd_uart16550_detect(uart)) <= 0) {
797 		printk(KERN_ERR "no UART detected at 0x%lx\n", iobase);
798 		snd_uart16550_free(uart);
799 		return -ENODEV;
800 	}
801 
802 	if (irq >= 0 && irq != SNDRV_AUTO_IRQ) {
803 		if (request_irq(irq, snd_uart16550_interrupt,
804 				0, "Serial MIDI", uart)) {
805 			snd_printk(KERN_WARNING
806 				   "irq %d busy. Using Polling.\n", irq);
807 		} else {
808 			uart->irq = irq;
809 		}
810 	}
811 	uart->divisor = base / speed;
812 	uart->speed = base / (unsigned int)uart->divisor;
813 	uart->speed_base = base;
814 	uart->prev_out = -1;
815 	uart->prev_in = 0;
816 	uart->rstatus = 0;
817 	memset(uart->prev_status, 0x80, sizeof(unsigned char) * SNDRV_SERIAL_MAX_OUTS);
818 	timer_setup(&uart->buffer_timer, snd_uart16550_buffer_timer, 0);
819 	uart->timer_running = 0;
820 
821 	/* Register device */
822 	if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, uart, &ops)) < 0) {
823 		snd_uart16550_free(uart);
824 		return err;
825 	}
826 
827 	switch (uart->adaptor) {
828 	case SNDRV_SERIAL_MS124W_SA:
829 	case SNDRV_SERIAL_MS124W_MB:
830 		/* MS-124W can draw power from RTS and DTR if they
831 		   are in opposite states. */
832 		outb(UART_MCR_RTS | (0&UART_MCR_DTR), uart->base + UART_MCR);
833 		break;
834 	case SNDRV_SERIAL_MS124T:
835 		/* MS-124T can draw power from RTS and/or DTR (preferably
836 		   both) if they are asserted. */
837 		outb(UART_MCR_RTS | UART_MCR_DTR, uart->base + UART_MCR);
838 		break;
839 	default:
840 		break;
841 	}
842 
843 	if (ruart)
844 		*ruart = uart;
845 
846 	return 0;
847 }
848 
849 static void snd_uart16550_substreams(struct snd_rawmidi_str *stream)
850 {
851 	struct snd_rawmidi_substream *substream;
852 
853 	list_for_each_entry(substream, &stream->substreams, list) {
854 		sprintf(substream->name, "Serial MIDI %d", substream->number + 1);
855 	}
856 }
857 
858 static int snd_uart16550_rmidi(struct snd_uart16550 *uart, int device,
859 			       int outs, int ins,
860 			       struct snd_rawmidi **rmidi)
861 {
862 	struct snd_rawmidi *rrawmidi;
863 	int err;
864 
865 	err = snd_rawmidi_new(uart->card, "UART Serial MIDI", device,
866 			      outs, ins, &rrawmidi);
867 	if (err < 0)
868 		return err;
869 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_INPUT,
870 			    &snd_uart16550_input);
871 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
872 			    &snd_uart16550_output);
873 	strcpy(rrawmidi->name, "Serial MIDI");
874 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT]);
875 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT]);
876 	rrawmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
877 			       SNDRV_RAWMIDI_INFO_INPUT |
878 			       SNDRV_RAWMIDI_INFO_DUPLEX;
879 	rrawmidi->private_data = uart;
880 	if (rmidi)
881 		*rmidi = rrawmidi;
882 	return 0;
883 }
884 
885 static int snd_serial_probe(struct platform_device *devptr)
886 {
887 	struct snd_card *card;
888 	struct snd_uart16550 *uart;
889 	int err;
890 	int dev = devptr->id;
891 
892 	switch (adaptor[dev]) {
893 	case SNDRV_SERIAL_SOUNDCANVAS:
894 		ins[dev] = 1;
895 		break;
896 	case SNDRV_SERIAL_MS124T:
897 	case SNDRV_SERIAL_MS124W_SA:
898 		outs[dev] = 1;
899 		ins[dev] = 1;
900 		break;
901 	case SNDRV_SERIAL_MS124W_MB:
902 		outs[dev] = 16;
903 		ins[dev] = 1;
904 		break;
905 	case SNDRV_SERIAL_GENERIC:
906 		break;
907 	default:
908 		snd_printk(KERN_ERR
909 			   "Adaptor type is out of range 0-%d (%d)\n",
910 			   SNDRV_SERIAL_MAX_ADAPTOR, adaptor[dev]);
911 		return -ENODEV;
912 	}
913 
914 	if (outs[dev] < 1 || outs[dev] > SNDRV_SERIAL_MAX_OUTS) {
915 		snd_printk(KERN_ERR
916 			   "Count of outputs is out of range 1-%d (%d)\n",
917 			   SNDRV_SERIAL_MAX_OUTS, outs[dev]);
918 		return -ENODEV;
919 	}
920 
921 	if (ins[dev] < 1 || ins[dev] > SNDRV_SERIAL_MAX_INS) {
922 		snd_printk(KERN_ERR
923 			   "Count of inputs is out of range 1-%d (%d)\n",
924 			   SNDRV_SERIAL_MAX_INS, ins[dev]);
925 		return -ENODEV;
926 	}
927 
928 	err  = snd_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
929 			    0, &card);
930 	if (err < 0)
931 		return err;
932 
933 	strcpy(card->driver, "Serial");
934 	strcpy(card->shortname, "Serial MIDI (UART16550A)");
935 
936 	if ((err = snd_uart16550_create(card,
937 					port[dev],
938 					irq[dev],
939 					speed[dev],
940 					base[dev],
941 					adaptor[dev],
942 					droponfull[dev],
943 					&uart)) < 0)
944 		goto _err;
945 
946 	err = snd_uart16550_rmidi(uart, 0, outs[dev], ins[dev], &uart->rmidi);
947 	if (err < 0)
948 		goto _err;
949 
950 	sprintf(card->longname, "%s [%s] at %#lx, irq %d",
951 		card->shortname,
952 		adaptor_names[uart->adaptor],
953 		uart->base,
954 		uart->irq);
955 
956 	if ((err = snd_card_register(card)) < 0)
957 		goto _err;
958 
959 	platform_set_drvdata(devptr, card);
960 	return 0;
961 
962  _err:
963 	snd_card_free(card);
964 	return err;
965 }
966 
967 static int snd_serial_remove(struct platform_device *devptr)
968 {
969 	snd_card_free(platform_get_drvdata(devptr));
970 	return 0;
971 }
972 
973 #define SND_SERIAL_DRIVER	"snd_serial_u16550"
974 
975 static struct platform_driver snd_serial_driver = {
976 	.probe		= snd_serial_probe,
977 	.remove		=  snd_serial_remove,
978 	.driver		= {
979 		.name	= SND_SERIAL_DRIVER,
980 	},
981 };
982 
983 static void snd_serial_unregister_all(void)
984 {
985 	int i;
986 
987 	for (i = 0; i < ARRAY_SIZE(devices); ++i)
988 		platform_device_unregister(devices[i]);
989 	platform_driver_unregister(&snd_serial_driver);
990 }
991 
992 static int __init alsa_card_serial_init(void)
993 {
994 	int i, cards, err;
995 
996 	if ((err = platform_driver_register(&snd_serial_driver)) < 0)
997 		return err;
998 
999 	cards = 0;
1000 	for (i = 0; i < SNDRV_CARDS; i++) {
1001 		struct platform_device *device;
1002 		if (! enable[i])
1003 			continue;
1004 		device = platform_device_register_simple(SND_SERIAL_DRIVER,
1005 							 i, NULL, 0);
1006 		if (IS_ERR(device))
1007 			continue;
1008 		if (!platform_get_drvdata(device)) {
1009 			platform_device_unregister(device);
1010 			continue;
1011 		}
1012 		devices[i] = device;
1013 		cards++;
1014 	}
1015 	if (! cards) {
1016 #ifdef MODULE
1017 		printk(KERN_ERR "serial midi soundcard not found or device busy\n");
1018 #endif
1019 		snd_serial_unregister_all();
1020 		return -ENODEV;
1021 	}
1022 	return 0;
1023 }
1024 
1025 static void __exit alsa_card_serial_exit(void)
1026 {
1027 	snd_serial_unregister_all();
1028 }
1029 
1030 module_init(alsa_card_serial_init)
1031 module_exit(alsa_card_serial_exit)
1032