xref: /linux/drivers/tty/serial/8250/8250_pnp.c (revision 762f99f4f3cb41a775b5157dd761217beba65873)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Probe for 8250/16550-type ISAPNP serial ports.
4  *
5  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
6  *
7  *  Copyright (C) 2001 Russell King, All Rights Reserved.
8  *
9  *  Ported to the Linux PnP Layer - (C) Adam Belay.
10  */
11 #include <linux/module.h>
12 #include <linux/pci.h>
13 #include <linux/pnp.h>
14 #include <linux/string.h>
15 #include <linux/kernel.h>
16 #include <linux/property.h>
17 #include <linux/serial_core.h>
18 #include <linux/bitops.h>
19 
20 #include <asm/byteorder.h>
21 
22 #include "8250.h"
23 
24 #define UNKNOWN_DEV 0x3000
25 #define CIR_PORT	0x0800
26 
27 static const struct pnp_device_id pnp_dev_table[] = {
28 	/* Archtek America Corp. */
29 	/* Archtek SmartLink Modem 3334BT Plug & Play */
30 	{	"AAC000F",		0	},
31 	/* Anchor Datacomm BV */
32 	/* SXPro 144 External Data Fax Modem Plug & Play */
33 	{	"ADC0001",		0	},
34 	/* SXPro 288 External Data Fax Modem Plug & Play */
35 	{	"ADC0002",		0	},
36 	/* PROLiNK 1456VH ISA PnP K56flex Fax Modem */
37 	{	"AEI0250",		0	},
38 	/* Actiontec ISA PNP 56K X2 Fax Modem */
39 	{	"AEI1240",		0	},
40 	/* Rockwell 56K ACF II Fax+Data+Voice Modem */
41 	{	"AKY1021",		0 /*SPCI_FL_NO_SHIRQ*/	},
42 	/*
43 	 * ALi Fast Infrared Controller
44 	 * Native driver (ali-ircc) is broken so at least
45 	 * it can be used with irtty-sir.
46 	 */
47 	{	"ALI5123",		0	},
48 	/* AZT3005 PnP SOUND DEVICE */
49 	{	"AZT4001",		0	},
50 	/* Best Data Products Inc. Smart One 336F PnP Modem */
51 	{	"BDP3336",		0	},
52 	/*  Boca Research */
53 	/* Boca Complete Ofc Communicator 14.4 Data-FAX */
54 	{	"BRI0A49",		0	},
55 	/* Boca Research 33,600 ACF Modem */
56 	{	"BRI1400",		0	},
57 	/* Boca 33.6 Kbps Internal FD34FSVD */
58 	{	"BRI3400",		0	},
59 	/* Boca 33.6 Kbps Internal FD34FSVD */
60 	{	"BRI0A49",		0	},
61 	/* Best Data Products Inc. Smart One 336F PnP Modem */
62 	{	"BDP3336",		0	},
63 	/* Computer Peripherals Inc */
64 	/* EuroViVa CommCenter-33.6 SP PnP */
65 	{	"CPI4050",		0	},
66 	/* Creative Labs */
67 	/* Creative Labs Phone Blaster 28.8 DSVD PnP Voice */
68 	{	"CTL3001",		0	},
69 	/* Creative Labs Modem Blaster 28.8 DSVD PnP Voice */
70 	{	"CTL3011",		0	},
71 	/* Davicom ISA 33.6K Modem */
72 	{	"DAV0336",		0	},
73 	/* Creative */
74 	/* Creative Modem Blaster Flash56 DI5601-1 */
75 	{	"DMB1032",		0	},
76 	/* Creative Modem Blaster V.90 DI5660 */
77 	{	"DMB2001",		0	},
78 	/* E-Tech */
79 	/* E-Tech CyberBULLET PC56RVP */
80 	{	"ETT0002",		0	},
81 	/* FUJITSU */
82 	/* Fujitsu 33600 PnP-I2 R Plug & Play */
83 	{	"FUJ0202",		0	},
84 	/* Fujitsu FMV-FX431 Plug & Play */
85 	{	"FUJ0205",		0	},
86 	/* Fujitsu 33600 PnP-I4 R Plug & Play */
87 	{	"FUJ0206",		0	},
88 	/* Fujitsu Fax Voice 33600 PNP-I5 R Plug & Play */
89 	{	"FUJ0209",		0	},
90 	/* Archtek America Corp. */
91 	/* Archtek SmartLink Modem 3334BT Plug & Play */
92 	{	"GVC000F",		0	},
93 	/* Archtek SmartLink Modem 3334BRV 33.6K Data Fax Voice */
94 	{	"GVC0303",		0	},
95 	/* Hayes */
96 	/* Hayes Optima 288 V.34-V.FC + FAX + Voice Plug & Play */
97 	{	"HAY0001",		0	},
98 	/* Hayes Optima 336 V.34 + FAX + Voice PnP */
99 	{	"HAY000C",		0	},
100 	/* Hayes Optima 336B V.34 + FAX + Voice PnP */
101 	{	"HAY000D",		0	},
102 	/* Hayes Accura 56K Ext Fax Modem PnP */
103 	{	"HAY5670",		0	},
104 	/* Hayes Accura 56K Ext Fax Modem PnP */
105 	{	"HAY5674",		0	},
106 	/* Hayes Accura 56K Fax Modem PnP */
107 	{	"HAY5675",		0	},
108 	/* Hayes 288, V.34 + FAX */
109 	{	"HAYF000",		0	},
110 	/* Hayes Optima 288 V.34 + FAX + Voice, Plug & Play */
111 	{	"HAYF001",		0	},
112 	/* IBM */
113 	/* IBM Thinkpad 701 Internal Modem Voice */
114 	{	"IBM0033",		0	},
115 	/* Intermec */
116 	/* Intermec CV60 touchscreen port */
117 	{	"PNP4972",		0	},
118 	/* Intertex */
119 	/* Intertex 28k8 33k6 Voice EXT PnP */
120 	{	"IXDC801",		0	},
121 	/* Intertex 33k6 56k Voice EXT PnP */
122 	{	"IXDC901",		0	},
123 	/* Intertex 28k8 33k6 Voice SP EXT PnP */
124 	{	"IXDD801",		0	},
125 	/* Intertex 33k6 56k Voice SP EXT PnP */
126 	{	"IXDD901",		0	},
127 	/* Intertex 28k8 33k6 Voice SP INT PnP */
128 	{	"IXDF401",		0	},
129 	/* Intertex 28k8 33k6 Voice SP EXT PnP */
130 	{	"IXDF801",		0	},
131 	/* Intertex 33k6 56k Voice SP EXT PnP */
132 	{	"IXDF901",		0	},
133 	/* Kortex International */
134 	/* KORTEX 28800 Externe PnP */
135 	{	"KOR4522",		0	},
136 	/* KXPro 33.6 Vocal ASVD PnP */
137 	{	"KORF661",		0	},
138 	/* Lasat */
139 	/* LASAT Internet 33600 PnP */
140 	{	"LAS4040",		0	},
141 	/* Lasat Safire 560 PnP */
142 	{	"LAS4540",		0	},
143 	/* Lasat Safire 336  PnP */
144 	{	"LAS5440",		0	},
145 	/* Microcom, Inc. */
146 	/* Microcom TravelPorte FAST V.34 Plug & Play */
147 	{	"MNP0281",		0	},
148 	/* Microcom DeskPorte V.34 FAST or FAST+ Plug & Play */
149 	{	"MNP0336",		0	},
150 	/* Microcom DeskPorte FAST EP 28.8 Plug & Play */
151 	{	"MNP0339",		0	},
152 	/* Microcom DeskPorte 28.8P Plug & Play */
153 	{	"MNP0342",		0	},
154 	/* Microcom DeskPorte FAST ES 28.8 Plug & Play */
155 	{	"MNP0500",		0	},
156 	/* Microcom DeskPorte FAST ES 28.8 Plug & Play */
157 	{	"MNP0501",		0	},
158 	/* Microcom DeskPorte 28.8S Internal Plug & Play */
159 	{	"MNP0502",		0	},
160 	/* Motorola */
161 	/* Motorola BitSURFR Plug & Play */
162 	{	"MOT1105",		0	},
163 	/* Motorola TA210 Plug & Play */
164 	{	"MOT1111",		0	},
165 	/* Motorola HMTA 200 (ISDN) Plug & Play */
166 	{	"MOT1114",		0	},
167 	/* Motorola BitSURFR Plug & Play */
168 	{	"MOT1115",		0	},
169 	/* Motorola Lifestyle 28.8 Internal */
170 	{	"MOT1190",		0	},
171 	/* Motorola V.3400 Plug & Play */
172 	{	"MOT1501",		0	},
173 	/* Motorola Lifestyle 28.8 V.34 Plug & Play */
174 	{	"MOT1502",		0	},
175 	/* Motorola Power 28.8 V.34 Plug & Play */
176 	{	"MOT1505",		0	},
177 	/* Motorola ModemSURFR External 28.8 Plug & Play */
178 	{	"MOT1509",		0	},
179 	/* Motorola Premier 33.6 Desktop Plug & Play */
180 	{	"MOT150A",		0	},
181 	/* Motorola VoiceSURFR 56K External PnP */
182 	{	"MOT150F",		0	},
183 	/* Motorola ModemSURFR 56K External PnP */
184 	{	"MOT1510",		0	},
185 	/* Motorola ModemSURFR 56K Internal PnP */
186 	{	"MOT1550",		0	},
187 	/* Motorola ModemSURFR Internal 28.8 Plug & Play */
188 	{	"MOT1560",		0	},
189 	/* Motorola Premier 33.6 Internal Plug & Play */
190 	{	"MOT1580",		0	},
191 	/* Motorola OnlineSURFR 28.8 Internal Plug & Play */
192 	{	"MOT15B0",		0	},
193 	/* Motorola VoiceSURFR 56K Internal PnP */
194 	{	"MOT15F0",		0	},
195 	/* Com 1 */
196 	/*  Deskline K56 Phone System PnP */
197 	{	"MVX00A1",		0	},
198 	/* PC Rider K56 Phone System PnP */
199 	{	"MVX00F2",		0	},
200 	/* NEC 98NOTE SPEAKER PHONE FAX MODEM(33600bps) */
201 	{	"nEC8241",		0	},
202 	/* Pace 56 Voice Internal Plug & Play Modem */
203 	{	"PMC2430",		0	},
204 	/* Generic */
205 	/* Generic standard PC COM port	 */
206 	{	"PNP0500",		0	},
207 	/* Generic 16550A-compatible COM port */
208 	{	"PNP0501",		0	},
209 	/* Compaq 14400 Modem */
210 	{	"PNPC000",		0	},
211 	/* Compaq 2400/9600 Modem */
212 	{	"PNPC001",		0	},
213 	/* Dial-Up Networking Serial Cable between 2 PCs */
214 	{	"PNPC031",		0	},
215 	/* Dial-Up Networking Parallel Cable between 2 PCs */
216 	{	"PNPC032",		0	},
217 	/* Standard 9600 bps Modem */
218 	{	"PNPC100",		0	},
219 	/* Standard 14400 bps Modem */
220 	{	"PNPC101",		0	},
221 	/*  Standard 28800 bps Modem*/
222 	{	"PNPC102",		0	},
223 	/*  Standard Modem*/
224 	{	"PNPC103",		0	},
225 	/*  Standard 9600 bps Modem*/
226 	{	"PNPC104",		0	},
227 	/*  Standard 14400 bps Modem*/
228 	{	"PNPC105",		0	},
229 	/*  Standard 28800 bps Modem*/
230 	{	"PNPC106",		0	},
231 	/*  Standard Modem */
232 	{	"PNPC107",		0	},
233 	/* Standard 9600 bps Modem */
234 	{	"PNPC108",		0	},
235 	/* Standard 14400 bps Modem */
236 	{	"PNPC109",		0	},
237 	/* Standard 28800 bps Modem */
238 	{	"PNPC10A",		0	},
239 	/* Standard Modem */
240 	{	"PNPC10B",		0	},
241 	/* Standard 9600 bps Modem */
242 	{	"PNPC10C",		0	},
243 	/* Standard 14400 bps Modem */
244 	{	"PNPC10D",		0	},
245 	/* Standard 28800 bps Modem */
246 	{	"PNPC10E",		0	},
247 	/* Standard Modem */
248 	{	"PNPC10F",		0	},
249 	/* Standard PCMCIA Card Modem */
250 	{	"PNP2000",		0	},
251 	/* Rockwell */
252 	/* Modular Technology */
253 	/* Rockwell 33.6 DPF Internal PnP */
254 	/* Modular Technology 33.6 Internal PnP */
255 	{	"ROK0030",		0	},
256 	/* Kortex International */
257 	/* KORTEX 14400 Externe PnP */
258 	{	"ROK0100",		0	},
259 	/* Rockwell 28.8 */
260 	{	"ROK4120",		0	},
261 	/* Viking Components, Inc */
262 	/* Viking 28.8 INTERNAL Fax+Data+Voice PnP */
263 	{	"ROK4920",		0	},
264 	/* Rockwell */
265 	/* British Telecom */
266 	/* Modular Technology */
267 	/* Rockwell 33.6 DPF External PnP */
268 	/* BT Prologue 33.6 External PnP */
269 	/* Modular Technology 33.6 External PnP */
270 	{	"RSS00A0",		0	},
271 	/* Viking 56K FAX INT */
272 	{	"RSS0262",		0	},
273 	/* K56 par,VV,Voice,Speakphone,AudioSpan,PnP */
274 	{       "RSS0250",              0       },
275 	/* SupraExpress 28.8 Data/Fax PnP modem */
276 	{	"SUP1310",		0	},
277 	/* SupraExpress 336i PnP Voice Modem */
278 	{	"SUP1381",		0	},
279 	/* SupraExpress 33.6 Data/Fax PnP modem */
280 	{	"SUP1421",		0	},
281 	/* SupraExpress 33.6 Data/Fax PnP modem */
282 	{	"SUP1590",		0	},
283 	/* SupraExpress 336i Sp ASVD */
284 	{	"SUP1620",		0	},
285 	/* SupraExpress 33.6 Data/Fax PnP modem */
286 	{	"SUP1760",		0	},
287 	/* SupraExpress 56i Sp Intl */
288 	{	"SUP2171",		0	},
289 	/* Phoebe Micro */
290 	/* Phoebe Micro 33.6 Data Fax 1433VQH Plug & Play */
291 	{	"TEX0011",		0	},
292 	/* Archtek America Corp. */
293 	/* Archtek SmartLink Modem 3334BT Plug & Play */
294 	{	"UAC000F",		0	},
295 	/* 3Com Corp. */
296 	/* Gateway Telepath IIvi 33.6 */
297 	{	"USR0000",		0	},
298 	/* U.S. Robotics Sporster 33.6K Fax INT PnP */
299 	{	"USR0002",		0	},
300 	/*  Sportster Vi 14.4 PnP FAX Voicemail */
301 	{	"USR0004",		0	},
302 	/* U.S. Robotics 33.6K Voice INT PnP */
303 	{	"USR0006",		0	},
304 	/* U.S. Robotics 33.6K Voice EXT PnP */
305 	{	"USR0007",		0	},
306 	/* U.S. Robotics Courier V.Everything INT PnP */
307 	{	"USR0009",		0	},
308 	/* U.S. Robotics 33.6K Voice INT PnP */
309 	{	"USR2002",		0	},
310 	/* U.S. Robotics 56K Voice INT PnP */
311 	{	"USR2070",		0	},
312 	/* U.S. Robotics 56K Voice EXT PnP */
313 	{	"USR2080",		0	},
314 	/* U.S. Robotics 56K FAX INT */
315 	{	"USR3031",		0	},
316 	/* U.S. Robotics 56K FAX INT */
317 	{	"USR3050",		0	},
318 	/* U.S. Robotics 56K Voice INT PnP */
319 	{	"USR3070",		0	},
320 	/* U.S. Robotics 56K Voice EXT PnP */
321 	{	"USR3080",		0	},
322 	/* U.S. Robotics 56K Voice INT PnP */
323 	{	"USR3090",		0	},
324 	/* U.S. Robotics 56K Message  */
325 	{	"USR9100",		0	},
326 	/* U.S. Robotics 56K FAX EXT PnP*/
327 	{	"USR9160",		0	},
328 	/* U.S. Robotics 56K FAX INT PnP*/
329 	{	"USR9170",		0	},
330 	/* U.S. Robotics 56K Voice EXT PnP*/
331 	{	"USR9180",		0	},
332 	/* U.S. Robotics 56K Voice INT PnP*/
333 	{	"USR9190",		0	},
334 	/* Wacom tablets */
335 	{	"WACFXXX",		0	},
336 	/* Compaq touchscreen */
337 	{       "FPI2002",              0 },
338 	/* Fujitsu Stylistic touchscreens */
339 	{       "FUJ02B2",              0 },
340 	{       "FUJ02B3",              0 },
341 	/* Fujitsu Stylistic LT touchscreens */
342 	{       "FUJ02B4",              0 },
343 	/* Passive Fujitsu Stylistic touchscreens */
344 	{       "FUJ02B6",              0 },
345 	{       "FUJ02B7",              0 },
346 	{       "FUJ02B8",              0 },
347 	{       "FUJ02B9",              0 },
348 	{       "FUJ02BC",              0 },
349 	/* Fujitsu Wacom Tablet PC device */
350 	{	"FUJ02E5",		0	},
351 	/* Fujitsu P-series tablet PC device */
352 	{	"FUJ02E6",		0	},
353 	/* Fujitsu Wacom 2FGT Tablet PC device */
354 	{	"FUJ02E7",		0	},
355 	/* Fujitsu Wacom 1FGT Tablet PC device */
356 	{	"FUJ02E9",		0	},
357 	/*
358 	 * LG C1 EXPRESS DUAL (C1-PB11A3) touch screen (actually a FUJ02E6
359 	 * in disguise).
360 	 */
361 	{	"LTS0001",		0       },
362 	/* Rockwell's (PORALiNK) 33600 INT PNP */
363 	{	"WCI0003",		0	},
364 	/* Unknown PnP modems */
365 	{	"PNPCXXX",		UNKNOWN_DEV	},
366 	/* More unknown PnP modems */
367 	{	"PNPDXXX",		UNKNOWN_DEV	},
368 	/*
369 	 * Winbond CIR port, should not be probed. We should keep track of
370 	 * it to prevent the legacy serial driver from probing it.
371 	 */
372 	{	"WEC1022",		CIR_PORT	},
373 	/*
374 	 * SMSC IrCC SIR/FIR port, should not be probed by serial driver as
375 	 * well so its own driver can bind to it.
376 	 */
377 	{	"SMCF010",		CIR_PORT	},
378 	{	"",			0	}
379 };
380 
381 MODULE_DEVICE_TABLE(pnp, pnp_dev_table);
382 
383 static const char *modem_names[] = {
384 	"MODEM", "Modem", "modem", "FAX", "Fax", "fax",
385 	"56K", "56k", "K56", "33.6", "28.8", "14.4",
386 	"33,600", "28,800", "14,400", "33.600", "28.800", "14.400",
387 	"33600", "28800", "14400", "V.90", "V.34", "V.32", NULL
388 };
389 
390 static bool check_name(const char *name)
391 {
392 	const char **tmp;
393 
394 	for (tmp = modem_names; *tmp; tmp++)
395 		if (strstr(name, *tmp))
396 			return true;
397 
398 	return false;
399 }
400 
401 static bool check_resources(struct pnp_dev *dev)
402 {
403 	static const resource_size_t base[] = {0x2f8, 0x3f8, 0x2e8, 0x3e8};
404 	unsigned int i;
405 
406 	for (i = 0; i < ARRAY_SIZE(base); i++) {
407 		if (pnp_possible_config(dev, IORESOURCE_IO, base[i], 8))
408 			return true;
409 	}
410 
411 	return false;
412 }
413 
414 /*
415  * Given a complete unknown PnP device, try to use some heuristics to
416  * detect modems. Currently use such heuristic set:
417  *     - dev->name or dev->bus->name must contain "modem" substring;
418  *     - device must have only one IO region (8 byte long) with base address
419  *       0x2e8, 0x3e8, 0x2f8 or 0x3f8.
420  *
421  * Such detection looks very ugly, but can detect at least some of numerous
422  * PnP modems, alternatively we must hardcode all modems in pnp_devices[]
423  * table.
424  */
425 static int serial_pnp_guess_board(struct pnp_dev *dev)
426 {
427 	if (!(check_name(pnp_dev_name(dev)) ||
428 	    (dev->card && check_name(dev->card->name))))
429 		return -ENODEV;
430 
431 	if (check_resources(dev))
432 		return 0;
433 
434 	return -ENODEV;
435 }
436 
437 static int
438 serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
439 {
440 	struct uart_8250_port uart, *port;
441 	int ret, line, flags = dev_id->driver_data;
442 
443 	if (flags & UNKNOWN_DEV) {
444 		ret = serial_pnp_guess_board(dev);
445 		if (ret < 0)
446 			return ret;
447 	}
448 
449 	memset(&uart, 0, sizeof(uart));
450 	if (pnp_irq_valid(dev, 0))
451 		uart.port.irq = pnp_irq(dev, 0);
452 	if ((flags & CIR_PORT) && pnp_port_valid(dev, 2)) {
453 		uart.port.iobase = pnp_port_start(dev, 2);
454 		uart.port.iotype = UPIO_PORT;
455 	} else if (pnp_port_valid(dev, 0)) {
456 		uart.port.iobase = pnp_port_start(dev, 0);
457 		uart.port.iotype = UPIO_PORT;
458 	} else if (pnp_mem_valid(dev, 0)) {
459 		uart.port.mapbase = pnp_mem_start(dev, 0);
460 		uart.port.iotype = UPIO_MEM;
461 		uart.port.flags = UPF_IOREMAP;
462 	} else
463 		return -ENODEV;
464 
465 	dev_dbg(&dev->dev,
466 		 "Setup PNP port: port %#lx, mem %#llx, irq %u, type %u\n",
467 		 uart.port.iobase, (unsigned long long)uart.port.mapbase,
468 		 uart.port.irq, uart.port.iotype);
469 
470 	if (flags & CIR_PORT) {
471 		uart.port.flags |= UPF_FIXED_PORT | UPF_FIXED_TYPE;
472 		uart.port.type = PORT_8250_CIR;
473 	}
474 
475 	uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
476 	if (pnp_irq_flags(dev, 0) & IORESOURCE_IRQ_SHAREABLE)
477 		uart.port.flags |= UPF_SHARE_IRQ;
478 	uart.port.uartclk = 1843200;
479 	device_property_read_u32(&dev->dev, "clock-frequency", &uart.port.uartclk);
480 	uart.port.dev = &dev->dev;
481 
482 	line = serial8250_register_8250_port(&uart);
483 	if (line < 0 || (flags & CIR_PORT))
484 		return -ENODEV;
485 
486 	port = serial8250_get_port(line);
487 	if (uart_console(&port->port))
488 		dev->capabilities |= PNP_CONSOLE;
489 
490 	pnp_set_drvdata(dev, (void *)((long)line + 1));
491 	return 0;
492 }
493 
494 static void serial_pnp_remove(struct pnp_dev *dev)
495 {
496 	long line = (long)pnp_get_drvdata(dev);
497 
498 	dev->capabilities &= ~PNP_CONSOLE;
499 	if (line)
500 		serial8250_unregister_port(line - 1);
501 }
502 
503 static int __maybe_unused serial_pnp_suspend(struct device *dev)
504 {
505 	long line = (long)dev_get_drvdata(dev);
506 
507 	if (!line)
508 		return -ENODEV;
509 	serial8250_suspend_port(line - 1);
510 	return 0;
511 }
512 
513 static int __maybe_unused serial_pnp_resume(struct device *dev)
514 {
515 	long line = (long)dev_get_drvdata(dev);
516 
517 	if (!line)
518 		return -ENODEV;
519 	serial8250_resume_port(line - 1);
520 	return 0;
521 }
522 
523 static SIMPLE_DEV_PM_OPS(serial_pnp_pm_ops, serial_pnp_suspend, serial_pnp_resume);
524 
525 static struct pnp_driver serial_pnp_driver = {
526 	.name		= "serial",
527 	.probe		= serial_pnp_probe,
528 	.remove		= serial_pnp_remove,
529 	.driver         = {
530 		.pm     = &serial_pnp_pm_ops,
531 	},
532 	.id_table	= pnp_dev_table,
533 };
534 
535 int serial8250_pnp_init(void)
536 {
537 	return pnp_register_driver(&serial_pnp_driver);
538 }
539 
540 void serial8250_pnp_exit(void)
541 {
542 	pnp_unregister_driver(&serial_pnp_driver);
543 }
544 
545