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1 /*
2  * devices.c
3  * (C) Copyright 1999 Randy Dunlap.
4  * (C) Copyright 1999,2000 Thomas Sailer <sailer@ife.ee.ethz.ch>.
5  *     (proc file per device)
6  * (C) Copyright 1999 Deti Fliegl (new USB architecture)
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; either version 2 of the License, or
11  * (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
21  *
22  *************************************************************
23  *
24  * <mountpoint>/devices contains USB topology, device, config, class,
25  * interface, & endpoint data.
26  *
27  * I considered using /proc/bus/usb/devices/device# for each device
28  * as it is attached or detached, but I didn't like this for some
29  * reason -- maybe it's just too deep of a directory structure.
30  * I also don't like looking in multiple places to gather and view
31  * the data.  Having only one file for ./devices also prevents race
32  * conditions that could arise if a program was reading device info
33  * for devices that are being removed (unplugged).  (That is, the
34  * program may find a directory for devnum_12 then try to open it,
35  * but it was just unplugged, so the directory is now deleted.
36  * But programs would just have to be prepared for situations like
37  * this in any plug-and-play environment.)
38  *
39  * 1999-12-16: Thomas Sailer <sailer@ife.ee.ethz.ch>
40  *   Converted the whole proc stuff to real
41  *   read methods. Now not the whole device list needs to fit
42  *   into one page, only the device list for one bus.
43  *   Added a poll method to /proc/bus/usb/devices, to wake
44  *   up an eventual usbd
45  * 2000-01-04: Thomas Sailer <sailer@ife.ee.ethz.ch>
46  *   Turned into its own filesystem
47  * 2000-07-05: Ashley Montanaro <ashley@compsoc.man.ac.uk>
48  *   Converted file reading routine to dump to buffer once
49  *   per device, not per bus
50  */
51 
52 #include <linux/fs.h>
53 #include <linux/mm.h>
54 #include <linux/gfp.h>
55 #include <linux/poll.h>
56 #include <linux/usb.h>
57 #include <linux/usbdevice_fs.h>
58 #include <linux/usb/hcd.h>
59 #include <linux/mutex.h>
60 #include <linux/uaccess.h>
61 
62 #include "usb.h"
63 
64 /* Define ALLOW_SERIAL_NUMBER if you want to see the serial number of devices */
65 #define ALLOW_SERIAL_NUMBER
66 
67 static const char format_topo[] =
68 /* T:  Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=dddd MxCh=dd */
69 "\nT:  Bus=%2.2d Lev=%2.2d Prnt=%2.2d Port=%2.2d Cnt=%2.2d Dev#=%3d Spd=%-4s MxCh=%2d\n";
70 
71 static const char format_string_manufacturer[] =
72 /* S:  Manufacturer=xxxx */
73   "S:  Manufacturer=%.100s\n";
74 
75 static const char format_string_product[] =
76 /* S:  Product=xxxx */
77   "S:  Product=%.100s\n";
78 
79 #ifdef ALLOW_SERIAL_NUMBER
80 static const char format_string_serialnumber[] =
81 /* S:  SerialNumber=xxxx */
82   "S:  SerialNumber=%.100s\n";
83 #endif
84 
85 static const char format_bandwidth[] =
86 /* B:  Alloc=ddd/ddd us (xx%), #Int=ddd, #Iso=ddd */
87   "B:  Alloc=%3d/%3d us (%2d%%), #Int=%3d, #Iso=%3d\n";
88 
89 static const char format_device1[] =
90 /* D:  Ver=xx.xx Cls=xx(sssss) Sub=xx Prot=xx MxPS=dd #Cfgs=dd */
91   "D:  Ver=%2x.%02x Cls=%02x(%-5s) Sub=%02x Prot=%02x MxPS=%2d #Cfgs=%3d\n";
92 
93 static const char format_device2[] =
94 /* P:  Vendor=xxxx ProdID=xxxx Rev=xx.xx */
95   "P:  Vendor=%04x ProdID=%04x Rev=%2x.%02x\n";
96 
97 static const char format_config[] =
98 /* C:  #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA */
99   "C:%c #Ifs=%2d Cfg#=%2d Atr=%02x MxPwr=%3dmA\n";
100 
101 static const char format_iad[] =
102 /* A:  FirstIf#=dd IfCount=dd Cls=xx(sssss) Sub=xx Prot=xx */
103   "A:  FirstIf#=%2d IfCount=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x\n";
104 
105 static const char format_iface[] =
106 /* I:  If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=xxxx*/
107   "I:%c If#=%2d Alt=%2d #EPs=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x Driver=%s\n";
108 
109 static const char format_endpt[] =
110 /* E:  Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=D?s */
111   "E:  Ad=%02x(%c) Atr=%02x(%-4s) MxPS=%4d Ivl=%d%cs\n";
112 
113 
114 /*
115  * Need access to the driver and USB bus lists.
116  * extern struct list_head usb_bus_list;
117  * However, these will come from functions that return ptrs to each of them.
118  */
119 
120 /*
121  * Wait for an connect/disconnect event to happen. We initialize
122  * the event counter with an odd number, and each event will increment
123  * the event counter by two, so it will always _stay_ odd. That means
124  * that it will never be zero, so "event 0" will never match a current
125  * event, and thus 'poll' will always trigger as readable for the first
126  * time it gets called.
127  */
128 static struct device_connect_event {
129 	atomic_t count;
130 	wait_queue_head_t wait;
131 } device_event = {
132 	.count = ATOMIC_INIT(1),
133 	.wait = __WAIT_QUEUE_HEAD_INITIALIZER(device_event.wait)
134 };
135 
136 struct class_info {
137 	int class;
138 	char *class_name;
139 };
140 
141 static const struct class_info clas_info[] = {
142 	/* max. 5 chars. per name string */
143 	{USB_CLASS_PER_INTERFACE,	">ifc"},
144 	{USB_CLASS_AUDIO,		"audio"},
145 	{USB_CLASS_COMM,		"comm."},
146 	{USB_CLASS_HID,			"HID"},
147 	{USB_CLASS_PHYSICAL,		"PID"},
148 	{USB_CLASS_STILL_IMAGE,		"still"},
149 	{USB_CLASS_PRINTER,		"print"},
150 	{USB_CLASS_MASS_STORAGE,	"stor."},
151 	{USB_CLASS_HUB,			"hub"},
152 	{USB_CLASS_CDC_DATA,		"data"},
153 	{USB_CLASS_CSCID,		"scard"},
154 	{USB_CLASS_CONTENT_SEC,		"c-sec"},
155 	{USB_CLASS_VIDEO,		"video"},
156 	{USB_CLASS_WIRELESS_CONTROLLER,	"wlcon"},
157 	{USB_CLASS_MISC,		"misc"},
158 	{USB_CLASS_APP_SPEC,		"app."},
159 	{USB_CLASS_VENDOR_SPEC,		"vend."},
160 	{-1,				"unk."}		/* leave as last */
161 };
162 
163 /*****************************************************************/
164 
usbfs_conn_disc_event(void)165 void usbfs_conn_disc_event(void)
166 {
167 	atomic_add(2, &device_event.count);
168 	wake_up(&device_event.wait);
169 }
170 
class_decode(const int class)171 static const char *class_decode(const int class)
172 {
173 	int ix;
174 
175 	for (ix = 0; clas_info[ix].class != -1; ix++)
176 		if (clas_info[ix].class == class)
177 			break;
178 	return clas_info[ix].class_name;
179 }
180 
usb_dump_endpoint_descriptor(int speed,char * start,char * end,const struct usb_endpoint_descriptor * desc)181 static char *usb_dump_endpoint_descriptor(int speed, char *start, char *end,
182 				const struct usb_endpoint_descriptor *desc)
183 {
184 	char dir, unit, *type;
185 	unsigned interval, bandwidth = 1;
186 
187 	if (start > end)
188 		return start;
189 
190 	dir = usb_endpoint_dir_in(desc) ? 'I' : 'O';
191 
192 	if (speed == USB_SPEED_HIGH) {
193 		switch (usb_endpoint_maxp(desc) & (0x03 << 11)) {
194 		case 1 << 11:
195 			bandwidth = 2; break;
196 		case 2 << 11:
197 			bandwidth = 3; break;
198 		}
199 	}
200 
201 	/* this isn't checking for illegal values */
202 	switch (usb_endpoint_type(desc)) {
203 	case USB_ENDPOINT_XFER_CONTROL:
204 		type = "Ctrl";
205 		if (speed == USB_SPEED_HIGH)	/* uframes per NAK */
206 			interval = desc->bInterval;
207 		else
208 			interval = 0;
209 		dir = 'B';			/* ctrl is bidirectional */
210 		break;
211 	case USB_ENDPOINT_XFER_ISOC:
212 		type = "Isoc";
213 		interval = 1 << (desc->bInterval - 1);
214 		break;
215 	case USB_ENDPOINT_XFER_BULK:
216 		type = "Bulk";
217 		if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
218 			interval = desc->bInterval;
219 		else
220 			interval = 0;
221 		break;
222 	case USB_ENDPOINT_XFER_INT:
223 		type = "Int.";
224 		if (speed == USB_SPEED_HIGH || speed == USB_SPEED_SUPER)
225 			interval = 1 << (desc->bInterval - 1);
226 		else
227 			interval = desc->bInterval;
228 		break;
229 	default:	/* "can't happen" */
230 		return start;
231 	}
232 	interval *= (speed == USB_SPEED_HIGH ||
233 		     speed == USB_SPEED_SUPER) ? 125 : 1000;
234 	if (interval % 1000)
235 		unit = 'u';
236 	else {
237 		unit = 'm';
238 		interval /= 1000;
239 	}
240 
241 	start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
242 			 desc->bmAttributes, type,
243 			 (usb_endpoint_maxp(desc) & 0x07ff) *
244 			 bandwidth,
245 			 interval, unit);
246 	return start;
247 }
248 
usb_dump_interface_descriptor(char * start,char * end,const struct usb_interface_cache * intfc,const struct usb_interface * iface,int setno)249 static char *usb_dump_interface_descriptor(char *start, char *end,
250 					const struct usb_interface_cache *intfc,
251 					const struct usb_interface *iface,
252 					int setno)
253 {
254 	const struct usb_interface_descriptor *desc;
255 	const char *driver_name = "";
256 	int active = 0;
257 
258 	if (start > end)
259 		return start;
260 	desc = &intfc->altsetting[setno].desc;
261 	if (iface) {
262 		driver_name = (iface->dev.driver
263 				? iface->dev.driver->name
264 				: "(none)");
265 		active = (desc == &iface->cur_altsetting->desc);
266 	}
267 	start += sprintf(start, format_iface,
268 			 active ? '*' : ' ',	/* mark active altsetting */
269 			 desc->bInterfaceNumber,
270 			 desc->bAlternateSetting,
271 			 desc->bNumEndpoints,
272 			 desc->bInterfaceClass,
273 			 class_decode(desc->bInterfaceClass),
274 			 desc->bInterfaceSubClass,
275 			 desc->bInterfaceProtocol,
276 			 driver_name);
277 	return start;
278 }
279 
usb_dump_interface(int speed,char * start,char * end,const struct usb_interface_cache * intfc,const struct usb_interface * iface,int setno)280 static char *usb_dump_interface(int speed, char *start, char *end,
281 				const struct usb_interface_cache *intfc,
282 				const struct usb_interface *iface, int setno)
283 {
284 	const struct usb_host_interface *desc = &intfc->altsetting[setno];
285 	int i;
286 
287 	start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
288 	for (i = 0; i < desc->desc.bNumEndpoints; i++) {
289 		if (start > end)
290 			return start;
291 		start = usb_dump_endpoint_descriptor(speed,
292 				start, end, &desc->endpoint[i].desc);
293 	}
294 	return start;
295 }
296 
usb_dump_iad_descriptor(char * start,char * end,const struct usb_interface_assoc_descriptor * iad)297 static char *usb_dump_iad_descriptor(char *start, char *end,
298 			const struct usb_interface_assoc_descriptor *iad)
299 {
300 	if (start > end)
301 		return start;
302 	start += sprintf(start, format_iad,
303 			 iad->bFirstInterface,
304 			 iad->bInterfaceCount,
305 			 iad->bFunctionClass,
306 			 class_decode(iad->bFunctionClass),
307 			 iad->bFunctionSubClass,
308 			 iad->bFunctionProtocol);
309 	return start;
310 }
311 
312 /* TBD:
313  * 0. TBDs
314  * 1. marking active interface altsettings (code lists all, but should mark
315  *    which ones are active, if any)
316  */
usb_dump_config_descriptor(char * start,char * end,const struct usb_config_descriptor * desc,int active)317 static char *usb_dump_config_descriptor(char *start, char *end,
318 				const struct usb_config_descriptor *desc,
319 				int active)
320 {
321 	if (start > end)
322 		return start;
323 	start += sprintf(start, format_config,
324 			 /* mark active/actual/current cfg. */
325 			 active ? '*' : ' ',
326 			 desc->bNumInterfaces,
327 			 desc->bConfigurationValue,
328 			 desc->bmAttributes,
329 			 desc->bMaxPower * 2);
330 	return start;
331 }
332 
usb_dump_config(int speed,char * start,char * end,const struct usb_host_config * config,int active)333 static char *usb_dump_config(int speed, char *start, char *end,
334 			     const struct usb_host_config *config, int active)
335 {
336 	int i, j;
337 	struct usb_interface_cache *intfc;
338 	struct usb_interface *interface;
339 
340 	if (start > end)
341 		return start;
342 	if (!config)
343 		/* getting these some in 2.3.7; none in 2.3.6 */
344 		return start + sprintf(start, "(null Cfg. desc.)\n");
345 	start = usb_dump_config_descriptor(start, end, &config->desc, active);
346 	for (i = 0; i < USB_MAXIADS; i++) {
347 		if (config->intf_assoc[i] == NULL)
348 			break;
349 		start = usb_dump_iad_descriptor(start, end,
350 					config->intf_assoc[i]);
351 	}
352 	for (i = 0; i < config->desc.bNumInterfaces; i++) {
353 		intfc = config->intf_cache[i];
354 		interface = config->interface[i];
355 		for (j = 0; j < intfc->num_altsetting; j++) {
356 			if (start > end)
357 				return start;
358 			start = usb_dump_interface(speed,
359 				start, end, intfc, interface, j);
360 		}
361 	}
362 	return start;
363 }
364 
365 /*
366  * Dump the different USB descriptors.
367  */
usb_dump_device_descriptor(char * start,char * end,const struct usb_device_descriptor * desc)368 static char *usb_dump_device_descriptor(char *start, char *end,
369 				const struct usb_device_descriptor *desc)
370 {
371 	u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
372 	u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
373 
374 	if (start > end)
375 		return start;
376 	start += sprintf(start, format_device1,
377 			  bcdUSB >> 8, bcdUSB & 0xff,
378 			  desc->bDeviceClass,
379 			  class_decode(desc->bDeviceClass),
380 			  desc->bDeviceSubClass,
381 			  desc->bDeviceProtocol,
382 			  desc->bMaxPacketSize0,
383 			  desc->bNumConfigurations);
384 	if (start > end)
385 		return start;
386 	start += sprintf(start, format_device2,
387 			 le16_to_cpu(desc->idVendor),
388 			 le16_to_cpu(desc->idProduct),
389 			 bcdDevice >> 8, bcdDevice & 0xff);
390 	return start;
391 }
392 
393 /*
394  * Dump the different strings that this device holds.
395  */
usb_dump_device_strings(char * start,char * end,struct usb_device * dev)396 static char *usb_dump_device_strings(char *start, char *end,
397 				     struct usb_device *dev)
398 {
399 	if (start > end)
400 		return start;
401 	if (dev->manufacturer)
402 		start += sprintf(start, format_string_manufacturer,
403 				 dev->manufacturer);
404 	if (start > end)
405 		goto out;
406 	if (dev->product)
407 		start += sprintf(start, format_string_product, dev->product);
408 	if (start > end)
409 		goto out;
410 #ifdef ALLOW_SERIAL_NUMBER
411 	if (dev->serial)
412 		start += sprintf(start, format_string_serialnumber,
413 				 dev->serial);
414 #endif
415  out:
416 	return start;
417 }
418 
usb_dump_desc(char * start,char * end,struct usb_device * dev)419 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
420 {
421 	int i;
422 
423 	if (start > end)
424 		return start;
425 
426 	start = usb_dump_device_descriptor(start, end, &dev->descriptor);
427 
428 	if (start > end)
429 		return start;
430 
431 	start = usb_dump_device_strings(start, end, dev);
432 
433 	for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
434 		if (start > end)
435 			return start;
436 		start = usb_dump_config(dev->speed,
437 				start, end, dev->config + i,
438 				/* active ? */
439 				(dev->config + i) == dev->actconfig);
440 	}
441 	return start;
442 }
443 
444 
445 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
446 
usb_dump_hub_descriptor(char * start,char * end,const struct usb_hub_descriptor * desc)447 static char *usb_dump_hub_descriptor(char *start, char *end,
448 				     const struct usb_hub_descriptor *desc)
449 {
450 	int leng = USB_DT_HUB_NONVAR_SIZE;
451 	unsigned char *ptr = (unsigned char *)desc;
452 
453 	if (start > end)
454 		return start;
455 	start += sprintf(start, "Interface:");
456 	while (leng && start <= end) {
457 		start += sprintf(start, " %02x", *ptr);
458 		ptr++; leng--;
459 	}
460 	*start++ = '\n';
461 	return start;
462 }
463 
usb_dump_string(char * start,char * end,const struct usb_device * dev,char * id,int index)464 static char *usb_dump_string(char *start, char *end,
465 			     const struct usb_device *dev, char *id, int index)
466 {
467 	if (start > end)
468 		return start;
469 	start += sprintf(start, "Interface:");
470 	if (index <= dev->maxstring && dev->stringindex &&
471 	    dev->stringindex[index])
472 		start += sprintf(start, "%s: %.100s ", id,
473 				 dev->stringindex[index]);
474 	return start;
475 }
476 
477 #endif /* PROC_EXTRA */
478 
479 /*****************************************************************/
480 
481 /* This is a recursive function. Parameters:
482  * buffer - the user-space buffer to write data into
483  * nbytes - the maximum number of bytes to write
484  * skip_bytes - the number of bytes to skip before writing anything
485  * file_offset - the offset into the devices file on completion
486  * The caller must own the device lock.
487  */
usb_device_dump(char __user ** buffer,size_t * nbytes,loff_t * skip_bytes,loff_t * file_offset,struct usb_device * usbdev,struct usb_bus * bus,int level,int index,int count)488 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
489 			       loff_t *skip_bytes, loff_t *file_offset,
490 			       struct usb_device *usbdev, struct usb_bus *bus,
491 			       int level, int index, int count)
492 {
493 	int chix;
494 	int ret, cnt = 0;
495 	int parent_devnum = 0;
496 	char *pages_start, *data_end, *speed;
497 	unsigned int length;
498 	ssize_t total_written = 0;
499 
500 	/* don't bother with anything else if we're not writing any data */
501 	if (*nbytes <= 0)
502 		return 0;
503 
504 	if (level > MAX_TOPO_LEVEL)
505 		return 0;
506 	/* allocate 2^1 pages = 8K (on i386);
507 	 * should be more than enough for one device */
508 	pages_start = (char *)__get_free_pages(GFP_NOIO, 1);
509 	if (!pages_start)
510 		return -ENOMEM;
511 
512 	if (usbdev->parent && usbdev->parent->devnum != -1)
513 		parent_devnum = usbdev->parent->devnum;
514 	/*
515 	 * So the root hub's parent is 0 and any device that is
516 	 * plugged into the root hub has a parent of 0.
517 	 */
518 	switch (usbdev->speed) {
519 	case USB_SPEED_LOW:
520 		speed = "1.5"; break;
521 	case USB_SPEED_UNKNOWN:		/* usb 1.1 root hub code */
522 	case USB_SPEED_FULL:
523 		speed = "12"; break;
524 	case USB_SPEED_WIRELESS:	/* Wireless has no real fixed speed */
525 	case USB_SPEED_HIGH:
526 		speed = "480"; break;
527 	case USB_SPEED_SUPER:
528 		speed = "5000"; break;
529 	default:
530 		speed = "??";
531 	}
532 	data_end = pages_start + sprintf(pages_start, format_topo,
533 			bus->busnum, level, parent_devnum,
534 			index, count, usbdev->devnum,
535 			speed, usbdev->maxchild);
536 	/*
537 	 * level = topology-tier level;
538 	 * parent_devnum = parent device number;
539 	 * index = parent's connector number;
540 	 * count = device count at this level
541 	 */
542 	/* If this is the root hub, display the bandwidth information */
543 	if (level == 0) {
544 		int	max;
545 
546 		/* super/high speed reserves 80%, full/low reserves 90% */
547 		if (usbdev->speed == USB_SPEED_HIGH ||
548 		    usbdev->speed == USB_SPEED_SUPER)
549 			max = 800;
550 		else
551 			max = FRAME_TIME_MAX_USECS_ALLOC;
552 
553 		/* report "average" periodic allocation over a microsecond.
554 		 * the schedules are actually bursty, HCDs need to deal with
555 		 * that and just compute/report this average.
556 		 */
557 		data_end += sprintf(data_end, format_bandwidth,
558 				bus->bandwidth_allocated, max,
559 				(100 * bus->bandwidth_allocated + max / 2)
560 					/ max,
561 				bus->bandwidth_int_reqs,
562 				bus->bandwidth_isoc_reqs);
563 
564 	}
565 	data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
566 				 usbdev);
567 
568 	if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
569 		data_end += sprintf(data_end, "(truncated)\n");
570 
571 	length = data_end - pages_start;
572 	/* if we can start copying some data to the user */
573 	if (length > *skip_bytes) {
574 		length -= *skip_bytes;
575 		if (length > *nbytes)
576 			length = *nbytes;
577 		if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
578 			free_pages((unsigned long)pages_start, 1);
579 			return -EFAULT;
580 		}
581 		*nbytes -= length;
582 		*file_offset += length;
583 		total_written += length;
584 		*buffer += length;
585 		*skip_bytes = 0;
586 	} else
587 		*skip_bytes -= length;
588 
589 	free_pages((unsigned long)pages_start, 1);
590 
591 	/* Now look at all of this device's children. */
592 	for (chix = 0; chix < usbdev->maxchild; chix++) {
593 		struct usb_device *childdev = usbdev->children[chix];
594 
595 		if (childdev) {
596 			usb_lock_device(childdev);
597 			ret = usb_device_dump(buffer, nbytes, skip_bytes,
598 					      file_offset, childdev, bus,
599 					      level + 1, chix, ++cnt);
600 			usb_unlock_device(childdev);
601 			if (ret == -EFAULT)
602 				return total_written;
603 			total_written += ret;
604 		}
605 	}
606 	return total_written;
607 }
608 
usb_device_read(struct file * file,char __user * buf,size_t nbytes,loff_t * ppos)609 static ssize_t usb_device_read(struct file *file, char __user *buf,
610 			       size_t nbytes, loff_t *ppos)
611 {
612 	struct usb_bus *bus;
613 	ssize_t ret, total_written = 0;
614 	loff_t skip_bytes = *ppos;
615 
616 	if (*ppos < 0)
617 		return -EINVAL;
618 	if (nbytes <= 0)
619 		return 0;
620 	if (!access_ok(VERIFY_WRITE, buf, nbytes))
621 		return -EFAULT;
622 
623 	mutex_lock(&usb_bus_list_lock);
624 	/* print devices for all busses */
625 	list_for_each_entry(bus, &usb_bus_list, bus_list) {
626 		/* recurse through all children of the root hub */
627 		if (!bus_to_hcd(bus)->rh_registered)
628 			continue;
629 		usb_lock_device(bus->root_hub);
630 		ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos,
631 				      bus->root_hub, bus, 0, 0, 0);
632 		usb_unlock_device(bus->root_hub);
633 		if (ret < 0) {
634 			mutex_unlock(&usb_bus_list_lock);
635 			return ret;
636 		}
637 		total_written += ret;
638 	}
639 	mutex_unlock(&usb_bus_list_lock);
640 	return total_written;
641 }
642 
643 /* Kernel lock for "lastev" protection */
usb_device_poll(struct file * file,struct poll_table_struct * wait)644 static unsigned int usb_device_poll(struct file *file,
645 				    struct poll_table_struct *wait)
646 {
647 	unsigned int event_count;
648 
649 	poll_wait(file, &device_event.wait, wait);
650 
651 	event_count = atomic_read(&device_event.count);
652 	if (file->f_version != event_count) {
653 		file->f_version = event_count;
654 		return POLLIN | POLLRDNORM;
655 	}
656 
657 	return 0;
658 }
659 
usb_device_lseek(struct file * file,loff_t offset,int orig)660 static loff_t usb_device_lseek(struct file *file, loff_t offset, int orig)
661 {
662 	loff_t ret;
663 
664 	mutex_lock(&file->f_dentry->d_inode->i_mutex);
665 
666 	switch (orig) {
667 	case 0:
668 		file->f_pos = offset;
669 		ret = file->f_pos;
670 		break;
671 	case 1:
672 		file->f_pos += offset;
673 		ret = file->f_pos;
674 		break;
675 	case 2:
676 	default:
677 		ret = -EINVAL;
678 	}
679 
680 	mutex_unlock(&file->f_dentry->d_inode->i_mutex);
681 	return ret;
682 }
683 
684 const struct file_operations usbfs_devices_fops = {
685 	.llseek =	usb_device_lseek,
686 	.read =		usb_device_read,
687 	.poll =		usb_device_poll,
688 };
689