xref: /openbmc/linux/drivers/usb/class/usbtmc.c (revision cd5d5810)
1 /**
2  * drivers/usb/class/usbtmc.c - USB Test & Measurement class driver
3  *
4  * Copyright (C) 2007 Stefan Kopp, Gechingen, Germany
5  * Copyright (C) 2008 Novell, Inc.
6  * Copyright (C) 2008 Greg Kroah-Hartman <gregkh@suse.de>
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License
10  * as published by the Free Software Foundation; either version 2
11  * of the License, or (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  * The GNU General Public License is available at
19  * http://www.gnu.org/copyleft/gpl.html.
20  */
21 
22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23 
24 #include <linux/init.h>
25 #include <linux/module.h>
26 #include <linux/kernel.h>
27 #include <linux/fs.h>
28 #include <linux/uaccess.h>
29 #include <linux/kref.h>
30 #include <linux/slab.h>
31 #include <linux/mutex.h>
32 #include <linux/usb.h>
33 #include <linux/usb/tmc.h>
34 
35 
36 #define RIGOL			1
37 #define USBTMC_HEADER_SIZE	12
38 #define USBTMC_MINOR_BASE	176
39 
40 /*
41  * Size of driver internal IO buffer. Must be multiple of 4 and at least as
42  * large as wMaxPacketSize (which is usually 512 bytes).
43  */
44 #define USBTMC_SIZE_IOBUFFER	2048
45 
46 /* Default USB timeout (in milliseconds) */
47 #define USBTMC_TIMEOUT		5000
48 
49 /*
50  * Maximum number of read cycles to empty bulk in endpoint during CLEAR and
51  * ABORT_BULK_IN requests. Ends the loop if (for whatever reason) a short
52  * packet is never read.
53  */
54 #define USBTMC_MAX_READS_TO_CLEAR_BULK_IN	100
55 
56 static const struct usb_device_id usbtmc_devices[] = {
57 	{ USB_INTERFACE_INFO(USB_CLASS_APP_SPEC, 3, 0), },
58 	{ USB_INTERFACE_INFO(USB_CLASS_APP_SPEC, 3, 1), },
59 	{ 0, } /* terminating entry */
60 };
61 MODULE_DEVICE_TABLE(usb, usbtmc_devices);
62 
63 /*
64  * This structure is the capabilities for the device
65  * See section 4.2.1.8 of the USBTMC specification,
66  * and section 4.2.2 of the USBTMC usb488 subclass
67  * specification for details.
68  */
69 struct usbtmc_dev_capabilities {
70 	__u8 interface_capabilities;
71 	__u8 device_capabilities;
72 	__u8 usb488_interface_capabilities;
73 	__u8 usb488_device_capabilities;
74 };
75 
76 /* This structure holds private data for each USBTMC device. One copy is
77  * allocated for each USBTMC device in the driver's probe function.
78  */
79 struct usbtmc_device_data {
80 	const struct usb_device_id *id;
81 	struct usb_device *usb_dev;
82 	struct usb_interface *intf;
83 
84 	unsigned int bulk_in;
85 	unsigned int bulk_out;
86 
87 	u8 bTag;
88 	u8 bTag_last_write;	/* needed for abort */
89 	u8 bTag_last_read;	/* needed for abort */
90 
91 	u8 rigol_quirk;
92 
93 	/* attributes from the USB TMC spec for this device */
94 	u8 TermChar;
95 	bool TermCharEnabled;
96 	bool auto_abort;
97 
98 	bool zombie; /* fd of disconnected device */
99 
100 	struct usbtmc_dev_capabilities	capabilities;
101 	struct kref kref;
102 	struct mutex io_mutex;	/* only one i/o function running at a time */
103 };
104 #define to_usbtmc_data(d) container_of(d, struct usbtmc_device_data, kref)
105 
106 struct usbtmc_ID_rigol_quirk {
107 	__u16 idVendor;
108 	__u16 idProduct;
109 };
110 
111 static const struct usbtmc_ID_rigol_quirk usbtmc_id_quirk[] = {
112 	{ 0x1ab1, 0x0588 },
113 	{ 0, 0 }
114 };
115 
116 /* Forward declarations */
117 static struct usb_driver usbtmc_driver;
118 
119 static void usbtmc_delete(struct kref *kref)
120 {
121 	struct usbtmc_device_data *data = to_usbtmc_data(kref);
122 
123 	usb_put_dev(data->usb_dev);
124 }
125 
126 static int usbtmc_open(struct inode *inode, struct file *filp)
127 {
128 	struct usb_interface *intf;
129 	struct usbtmc_device_data *data;
130 	int retval = 0;
131 
132 	intf = usb_find_interface(&usbtmc_driver, iminor(inode));
133 	if (!intf) {
134 		pr_err("can not find device for minor %d", iminor(inode));
135 		return -ENODEV;
136 	}
137 
138 	data = usb_get_intfdata(intf);
139 	kref_get(&data->kref);
140 
141 	/* Store pointer in file structure's private data field */
142 	filp->private_data = data;
143 
144 	return retval;
145 }
146 
147 static int usbtmc_release(struct inode *inode, struct file *file)
148 {
149 	struct usbtmc_device_data *data = file->private_data;
150 
151 	kref_put(&data->kref, usbtmc_delete);
152 	return 0;
153 }
154 
155 static int usbtmc_ioctl_abort_bulk_in(struct usbtmc_device_data *data)
156 {
157 	u8 *buffer;
158 	struct device *dev;
159 	int rv;
160 	int n;
161 	int actual;
162 	struct usb_host_interface *current_setting;
163 	int max_size;
164 
165 	dev = &data->intf->dev;
166 	buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
167 	if (!buffer)
168 		return -ENOMEM;
169 
170 	rv = usb_control_msg(data->usb_dev,
171 			     usb_rcvctrlpipe(data->usb_dev, 0),
172 			     USBTMC_REQUEST_INITIATE_ABORT_BULK_IN,
173 			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
174 			     data->bTag_last_read, data->bulk_in,
175 			     buffer, 2, USBTMC_TIMEOUT);
176 
177 	if (rv < 0) {
178 		dev_err(dev, "usb_control_msg returned %d\n", rv);
179 		goto exit;
180 	}
181 
182 	dev_dbg(dev, "INITIATE_ABORT_BULK_IN returned %x\n", buffer[0]);
183 
184 	if (buffer[0] == USBTMC_STATUS_FAILED) {
185 		rv = 0;
186 		goto exit;
187 	}
188 
189 	if (buffer[0] != USBTMC_STATUS_SUCCESS) {
190 		dev_err(dev, "INITIATE_ABORT_BULK_IN returned %x\n",
191 			buffer[0]);
192 		rv = -EPERM;
193 		goto exit;
194 	}
195 
196 	max_size = 0;
197 	current_setting = data->intf->cur_altsetting;
198 	for (n = 0; n < current_setting->desc.bNumEndpoints; n++)
199 		if (current_setting->endpoint[n].desc.bEndpointAddress ==
200 			data->bulk_in)
201 			max_size = usb_endpoint_maxp(&current_setting->endpoint[n].desc);
202 
203 	if (max_size == 0) {
204 		dev_err(dev, "Couldn't get wMaxPacketSize\n");
205 		rv = -EPERM;
206 		goto exit;
207 	}
208 
209 	dev_dbg(&data->intf->dev, "wMaxPacketSize is %d\n", max_size);
210 
211 	n = 0;
212 
213 	do {
214 		dev_dbg(dev, "Reading from bulk in EP\n");
215 
216 		rv = usb_bulk_msg(data->usb_dev,
217 				  usb_rcvbulkpipe(data->usb_dev,
218 						  data->bulk_in),
219 				  buffer, USBTMC_SIZE_IOBUFFER,
220 				  &actual, USBTMC_TIMEOUT);
221 
222 		n++;
223 
224 		if (rv < 0) {
225 			dev_err(dev, "usb_bulk_msg returned %d\n", rv);
226 			goto exit;
227 		}
228 	} while ((actual == max_size) &&
229 		 (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
230 
231 	if (actual == max_size) {
232 		dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
233 			USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
234 		rv = -EPERM;
235 		goto exit;
236 	}
237 
238 	n = 0;
239 
240 usbtmc_abort_bulk_in_status:
241 	rv = usb_control_msg(data->usb_dev,
242 			     usb_rcvctrlpipe(data->usb_dev, 0),
243 			     USBTMC_REQUEST_CHECK_ABORT_BULK_IN_STATUS,
244 			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
245 			     0, data->bulk_in, buffer, 0x08,
246 			     USBTMC_TIMEOUT);
247 
248 	if (rv < 0) {
249 		dev_err(dev, "usb_control_msg returned %d\n", rv);
250 		goto exit;
251 	}
252 
253 	dev_dbg(dev, "INITIATE_ABORT_BULK_IN returned %x\n", buffer[0]);
254 
255 	if (buffer[0] == USBTMC_STATUS_SUCCESS) {
256 		rv = 0;
257 		goto exit;
258 	}
259 
260 	if (buffer[0] != USBTMC_STATUS_PENDING) {
261 		dev_err(dev, "INITIATE_ABORT_BULK_IN returned %x\n", buffer[0]);
262 		rv = -EPERM;
263 		goto exit;
264 	}
265 
266 	if (buffer[1] == 1)
267 		do {
268 			dev_dbg(dev, "Reading from bulk in EP\n");
269 
270 			rv = usb_bulk_msg(data->usb_dev,
271 					  usb_rcvbulkpipe(data->usb_dev,
272 							  data->bulk_in),
273 					  buffer, USBTMC_SIZE_IOBUFFER,
274 					  &actual, USBTMC_TIMEOUT);
275 
276 			n++;
277 
278 			if (rv < 0) {
279 				dev_err(dev, "usb_bulk_msg returned %d\n", rv);
280 				goto exit;
281 			}
282 		} while ((actual == max_size) &&
283 			 (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
284 
285 	if (actual == max_size) {
286 		dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
287 			USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
288 		rv = -EPERM;
289 		goto exit;
290 	}
291 
292 	goto usbtmc_abort_bulk_in_status;
293 
294 exit:
295 	kfree(buffer);
296 	return rv;
297 
298 }
299 
300 static int usbtmc_ioctl_abort_bulk_out(struct usbtmc_device_data *data)
301 {
302 	struct device *dev;
303 	u8 *buffer;
304 	int rv;
305 	int n;
306 
307 	dev = &data->intf->dev;
308 
309 	buffer = kmalloc(8, GFP_KERNEL);
310 	if (!buffer)
311 		return -ENOMEM;
312 
313 	rv = usb_control_msg(data->usb_dev,
314 			     usb_rcvctrlpipe(data->usb_dev, 0),
315 			     USBTMC_REQUEST_INITIATE_ABORT_BULK_OUT,
316 			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
317 			     data->bTag_last_write, data->bulk_out,
318 			     buffer, 2, USBTMC_TIMEOUT);
319 
320 	if (rv < 0) {
321 		dev_err(dev, "usb_control_msg returned %d\n", rv);
322 		goto exit;
323 	}
324 
325 	dev_dbg(dev, "INITIATE_ABORT_BULK_OUT returned %x\n", buffer[0]);
326 
327 	if (buffer[0] != USBTMC_STATUS_SUCCESS) {
328 		dev_err(dev, "INITIATE_ABORT_BULK_OUT returned %x\n",
329 			buffer[0]);
330 		rv = -EPERM;
331 		goto exit;
332 	}
333 
334 	n = 0;
335 
336 usbtmc_abort_bulk_out_check_status:
337 	rv = usb_control_msg(data->usb_dev,
338 			     usb_rcvctrlpipe(data->usb_dev, 0),
339 			     USBTMC_REQUEST_CHECK_ABORT_BULK_OUT_STATUS,
340 			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
341 			     0, data->bulk_out, buffer, 0x08,
342 			     USBTMC_TIMEOUT);
343 	n++;
344 	if (rv < 0) {
345 		dev_err(dev, "usb_control_msg returned %d\n", rv);
346 		goto exit;
347 	}
348 
349 	dev_dbg(dev, "CHECK_ABORT_BULK_OUT returned %x\n", buffer[0]);
350 
351 	if (buffer[0] == USBTMC_STATUS_SUCCESS)
352 		goto usbtmc_abort_bulk_out_clear_halt;
353 
354 	if ((buffer[0] == USBTMC_STATUS_PENDING) &&
355 	    (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN))
356 		goto usbtmc_abort_bulk_out_check_status;
357 
358 	rv = -EPERM;
359 	goto exit;
360 
361 usbtmc_abort_bulk_out_clear_halt:
362 	rv = usb_clear_halt(data->usb_dev,
363 			    usb_sndbulkpipe(data->usb_dev, data->bulk_out));
364 
365 	if (rv < 0) {
366 		dev_err(dev, "usb_control_msg returned %d\n", rv);
367 		goto exit;
368 	}
369 	rv = 0;
370 
371 exit:
372 	kfree(buffer);
373 	return rv;
374 }
375 
376 /*
377  * Sends a REQUEST_DEV_DEP_MSG_IN message on the Bulk-IN endpoint.
378  * @transfer_size: number of bytes to request from the device.
379  *
380  * See the USBTMC specification, Table 4.
381  *
382  * Also updates bTag_last_write.
383  */
384 static int send_request_dev_dep_msg_in(struct usbtmc_device_data *data, size_t transfer_size)
385 {
386 	int retval;
387 	u8 buffer[USBTMC_HEADER_SIZE];
388 	int actual;
389 
390 	/* Setup IO buffer for REQUEST_DEV_DEP_MSG_IN message
391 	 * Refer to class specs for details
392 	 */
393 	buffer[0] = 2;
394 	buffer[1] = data->bTag;
395 	buffer[2] = ~data->bTag;
396 	buffer[3] = 0; /* Reserved */
397 	buffer[4] = transfer_size >> 0;
398 	buffer[5] = transfer_size >> 8;
399 	buffer[6] = transfer_size >> 16;
400 	buffer[7] = transfer_size >> 24;
401 	buffer[8] = data->TermCharEnabled * 2;
402 	/* Use term character? */
403 	buffer[9] = data->TermChar;
404 	buffer[10] = 0; /* Reserved */
405 	buffer[11] = 0; /* Reserved */
406 
407 	/* Send bulk URB */
408 	retval = usb_bulk_msg(data->usb_dev,
409 			      usb_sndbulkpipe(data->usb_dev,
410 					      data->bulk_out),
411 			      buffer, USBTMC_HEADER_SIZE, &actual, USBTMC_TIMEOUT);
412 
413 	/* Store bTag (in case we need to abort) */
414 	data->bTag_last_write = data->bTag;
415 
416 	/* Increment bTag -- and increment again if zero */
417 	data->bTag++;
418 	if (!data->bTag)
419 		data->bTag++;
420 
421 	if (retval < 0) {
422 		dev_err(&data->intf->dev, "usb_bulk_msg in send_request_dev_dep_msg_in() returned %d\n", retval);
423 		return retval;
424 	}
425 
426 	return 0;
427 }
428 
429 static ssize_t usbtmc_read(struct file *filp, char __user *buf,
430 			   size_t count, loff_t *f_pos)
431 {
432 	struct usbtmc_device_data *data;
433 	struct device *dev;
434 	u32 n_characters;
435 	u8 *buffer;
436 	int actual;
437 	size_t done;
438 	size_t remaining;
439 	int retval;
440 	size_t this_part;
441 
442 	/* Get pointer to private data structure */
443 	data = filp->private_data;
444 	dev = &data->intf->dev;
445 
446 	buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
447 	if (!buffer)
448 		return -ENOMEM;
449 
450 	mutex_lock(&data->io_mutex);
451 	if (data->zombie) {
452 		retval = -ENODEV;
453 		goto exit;
454 	}
455 
456 	if (data->rigol_quirk) {
457 		dev_dbg(dev, "usb_bulk_msg_in: count(%zu)\n", count);
458 
459 		retval = send_request_dev_dep_msg_in(data, count);
460 
461 		if (retval < 0) {
462 			if (data->auto_abort)
463 				usbtmc_ioctl_abort_bulk_out(data);
464 			goto exit;
465 		}
466 	}
467 
468 	/* Loop until we have fetched everything we requested */
469 	remaining = count;
470 	this_part = remaining;
471 	done = 0;
472 
473 	while (remaining > 0) {
474 		if (!data->rigol_quirk) {
475 			dev_dbg(dev, "usb_bulk_msg_in: remaining(%zu), count(%zu)\n", remaining, count);
476 
477 			if (remaining > USBTMC_SIZE_IOBUFFER - USBTMC_HEADER_SIZE - 3)
478 				this_part = USBTMC_SIZE_IOBUFFER - USBTMC_HEADER_SIZE - 3;
479 			else
480 				this_part = remaining;
481 
482 			retval = send_request_dev_dep_msg_in(data, this_part);
483 			if (retval < 0) {
484 			dev_err(dev, "usb_bulk_msg returned %d\n", retval);
485 				if (data->auto_abort)
486 					usbtmc_ioctl_abort_bulk_out(data);
487 				goto exit;
488 			}
489 		}
490 
491 		/* Send bulk URB */
492 		retval = usb_bulk_msg(data->usb_dev,
493 				      usb_rcvbulkpipe(data->usb_dev,
494 						      data->bulk_in),
495 				      buffer, USBTMC_SIZE_IOBUFFER, &actual,
496 				      USBTMC_TIMEOUT);
497 
498 		dev_dbg(dev, "usb_bulk_msg: retval(%u), done(%zu), remaining(%zu), actual(%d)\n", retval, done, remaining, actual);
499 
500 		/* Store bTag (in case we need to abort) */
501 		data->bTag_last_read = data->bTag;
502 
503 		if (retval < 0) {
504 			dev_dbg(dev, "Unable to read data, error %d\n", retval);
505 			if (data->auto_abort)
506 				usbtmc_ioctl_abort_bulk_in(data);
507 			goto exit;
508 		}
509 
510 		/* Parse header in first packet */
511 		if ((done == 0) || !data->rigol_quirk) {
512 			/* Sanity checks for the header */
513 			if (actual < USBTMC_HEADER_SIZE) {
514 				dev_err(dev, "Device sent too small first packet: %u < %u\n", actual, USBTMC_HEADER_SIZE);
515 				if (data->auto_abort)
516 					usbtmc_ioctl_abort_bulk_in(data);
517 				goto exit;
518 			}
519 
520 			if (buffer[0] != 2) {
521 				dev_err(dev, "Device sent reply with wrong MsgID: %u != 2\n", buffer[0]);
522 				if (data->auto_abort)
523 					usbtmc_ioctl_abort_bulk_in(data);
524 				goto exit;
525 			}
526 
527 			if (buffer[1] != data->bTag_last_write) {
528 				dev_err(dev, "Device sent reply with wrong bTag: %u != %u\n", buffer[1], data->bTag_last_write);
529 				if (data->auto_abort)
530 					usbtmc_ioctl_abort_bulk_in(data);
531 				goto exit;
532 			}
533 
534 			/* How many characters did the instrument send? */
535 			n_characters = buffer[4] +
536 				       (buffer[5] << 8) +
537 				       (buffer[6] << 16) +
538 				       (buffer[7] << 24);
539 
540 			if (n_characters > this_part) {
541 				dev_err(dev, "Device wants to return more data than requested: %u > %zu\n", n_characters, count);
542 				if (data->auto_abort)
543 					usbtmc_ioctl_abort_bulk_in(data);
544 				goto exit;
545 			}
546 
547 			/* Remove the USBTMC header */
548 			actual -= USBTMC_HEADER_SIZE;
549 
550 			/* Check if the message is smaller than requested */
551 			if (data->rigol_quirk) {
552 				if (remaining > n_characters)
553 					remaining = n_characters;
554 				/* Remove padding if it exists */
555 				if (actual > remaining)
556 					actual = remaining;
557 			}
558 			else {
559 				if (this_part > n_characters)
560 					this_part = n_characters;
561 				/* Remove padding if it exists */
562 				if (actual > this_part)
563 					actual = this_part;
564 			}
565 
566 			dev_dbg(dev, "Bulk-IN header: N_characters(%u), bTransAttr(%u)\n", n_characters, buffer[8]);
567 
568 			remaining -= actual;
569 
570 			/* Terminate if end-of-message bit received from device */
571 			if ((buffer[8] & 0x01) && (actual >= n_characters))
572 				remaining = 0;
573 
574 			dev_dbg(dev, "Bulk-IN header: remaining(%zu), buf(%p), buffer(%p) done(%zu)\n", remaining,buf,buffer,done);
575 
576 
577 			/* Copy buffer to user space */
578 			if (copy_to_user(buf + done, &buffer[USBTMC_HEADER_SIZE], actual)) {
579 				/* There must have been an addressing problem */
580 				retval = -EFAULT;
581 				goto exit;
582 			}
583 			done += actual;
584 		}
585 		else  {
586 			if (actual > remaining)
587 				actual = remaining;
588 
589 			remaining -= actual;
590 
591 			dev_dbg(dev, "Bulk-IN header cont: actual(%u), done(%zu), remaining(%zu), buf(%p), buffer(%p)\n", actual, done, remaining,buf,buffer);
592 
593 			/* Copy buffer to user space */
594 			if (copy_to_user(buf + done, buffer, actual)) {
595 				/* There must have been an addressing problem */
596 				retval = -EFAULT;
597 				goto exit;
598 			}
599 			done += actual;
600 		}
601 	}
602 
603 	/* Update file position value */
604 	*f_pos = *f_pos + done;
605 	retval = done;
606 
607 exit:
608 	mutex_unlock(&data->io_mutex);
609 	kfree(buffer);
610 	return retval;
611 }
612 
613 static ssize_t usbtmc_write(struct file *filp, const char __user *buf,
614 			    size_t count, loff_t *f_pos)
615 {
616 	struct usbtmc_device_data *data;
617 	u8 *buffer;
618 	int retval;
619 	int actual;
620 	unsigned long int n_bytes;
621 	int remaining;
622 	int done;
623 	int this_part;
624 
625 	data = filp->private_data;
626 
627 	buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
628 	if (!buffer)
629 		return -ENOMEM;
630 
631 	mutex_lock(&data->io_mutex);
632 	if (data->zombie) {
633 		retval = -ENODEV;
634 		goto exit;
635 	}
636 
637 	remaining = count;
638 	done = 0;
639 
640 	while (remaining > 0) {
641 		if (remaining > USBTMC_SIZE_IOBUFFER - USBTMC_HEADER_SIZE) {
642 			this_part = USBTMC_SIZE_IOBUFFER - USBTMC_HEADER_SIZE;
643 			buffer[8] = 0;
644 		} else {
645 			this_part = remaining;
646 			buffer[8] = 1;
647 		}
648 
649 		/* Setup IO buffer for DEV_DEP_MSG_OUT message */
650 		buffer[0] = 1;
651 		buffer[1] = data->bTag;
652 		buffer[2] = ~data->bTag;
653 		buffer[3] = 0; /* Reserved */
654 		buffer[4] = this_part >> 0;
655 		buffer[5] = this_part >> 8;
656 		buffer[6] = this_part >> 16;
657 		buffer[7] = this_part >> 24;
658 		/* buffer[8] is set above... */
659 		buffer[9] = 0; /* Reserved */
660 		buffer[10] = 0; /* Reserved */
661 		buffer[11] = 0; /* Reserved */
662 
663 		if (copy_from_user(&buffer[USBTMC_HEADER_SIZE], buf + done, this_part)) {
664 			retval = -EFAULT;
665 			goto exit;
666 		}
667 
668 		n_bytes = roundup(USBTMC_HEADER_SIZE + this_part, 4);
669 		memset(buffer + USBTMC_HEADER_SIZE + this_part, 0, n_bytes - (USBTMC_HEADER_SIZE + this_part));
670 
671 		do {
672 			retval = usb_bulk_msg(data->usb_dev,
673 					      usb_sndbulkpipe(data->usb_dev,
674 							      data->bulk_out),
675 					      buffer, n_bytes,
676 					      &actual, USBTMC_TIMEOUT);
677 			if (retval != 0)
678 				break;
679 			n_bytes -= actual;
680 		} while (n_bytes);
681 
682 		data->bTag_last_write = data->bTag;
683 		data->bTag++;
684 
685 		if (!data->bTag)
686 			data->bTag++;
687 
688 		if (retval < 0) {
689 			dev_err(&data->intf->dev,
690 				"Unable to send data, error %d\n", retval);
691 			if (data->auto_abort)
692 				usbtmc_ioctl_abort_bulk_out(data);
693 			goto exit;
694 		}
695 
696 		remaining -= this_part;
697 		done += this_part;
698 	}
699 
700 	retval = count;
701 exit:
702 	mutex_unlock(&data->io_mutex);
703 	kfree(buffer);
704 	return retval;
705 }
706 
707 static int usbtmc_ioctl_clear(struct usbtmc_device_data *data)
708 {
709 	struct usb_host_interface *current_setting;
710 	struct usb_endpoint_descriptor *desc;
711 	struct device *dev;
712 	u8 *buffer;
713 	int rv;
714 	int n;
715 	int actual;
716 	int max_size;
717 
718 	dev = &data->intf->dev;
719 
720 	dev_dbg(dev, "Sending INITIATE_CLEAR request\n");
721 
722 	buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
723 	if (!buffer)
724 		return -ENOMEM;
725 
726 	rv = usb_control_msg(data->usb_dev,
727 			     usb_rcvctrlpipe(data->usb_dev, 0),
728 			     USBTMC_REQUEST_INITIATE_CLEAR,
729 			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
730 			     0, 0, buffer, 1, USBTMC_TIMEOUT);
731 	if (rv < 0) {
732 		dev_err(dev, "usb_control_msg returned %d\n", rv);
733 		goto exit;
734 	}
735 
736 	dev_dbg(dev, "INITIATE_CLEAR returned %x\n", buffer[0]);
737 
738 	if (buffer[0] != USBTMC_STATUS_SUCCESS) {
739 		dev_err(dev, "INITIATE_CLEAR returned %x\n", buffer[0]);
740 		rv = -EPERM;
741 		goto exit;
742 	}
743 
744 	max_size = 0;
745 	current_setting = data->intf->cur_altsetting;
746 	for (n = 0; n < current_setting->desc.bNumEndpoints; n++) {
747 		desc = &current_setting->endpoint[n].desc;
748 		if (desc->bEndpointAddress == data->bulk_in)
749 			max_size = usb_endpoint_maxp(desc);
750 	}
751 
752 	if (max_size == 0) {
753 		dev_err(dev, "Couldn't get wMaxPacketSize\n");
754 		rv = -EPERM;
755 		goto exit;
756 	}
757 
758 	dev_dbg(dev, "wMaxPacketSize is %d\n", max_size);
759 
760 	n = 0;
761 
762 usbtmc_clear_check_status:
763 
764 	dev_dbg(dev, "Sending CHECK_CLEAR_STATUS request\n");
765 
766 	rv = usb_control_msg(data->usb_dev,
767 			     usb_rcvctrlpipe(data->usb_dev, 0),
768 			     USBTMC_REQUEST_CHECK_CLEAR_STATUS,
769 			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
770 			     0, 0, buffer, 2, USBTMC_TIMEOUT);
771 	if (rv < 0) {
772 		dev_err(dev, "usb_control_msg returned %d\n", rv);
773 		goto exit;
774 	}
775 
776 	dev_dbg(dev, "CHECK_CLEAR_STATUS returned %x\n", buffer[0]);
777 
778 	if (buffer[0] == USBTMC_STATUS_SUCCESS)
779 		goto usbtmc_clear_bulk_out_halt;
780 
781 	if (buffer[0] != USBTMC_STATUS_PENDING) {
782 		dev_err(dev, "CHECK_CLEAR_STATUS returned %x\n", buffer[0]);
783 		rv = -EPERM;
784 		goto exit;
785 	}
786 
787 	if (buffer[1] == 1)
788 		do {
789 			dev_dbg(dev, "Reading from bulk in EP\n");
790 
791 			rv = usb_bulk_msg(data->usb_dev,
792 					  usb_rcvbulkpipe(data->usb_dev,
793 							  data->bulk_in),
794 					  buffer, USBTMC_SIZE_IOBUFFER,
795 					  &actual, USBTMC_TIMEOUT);
796 			n++;
797 
798 			if (rv < 0) {
799 				dev_err(dev, "usb_control_msg returned %d\n",
800 					rv);
801 				goto exit;
802 			}
803 		} while ((actual == max_size) &&
804 			  (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
805 
806 	if (actual == max_size) {
807 		dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
808 			USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
809 		rv = -EPERM;
810 		goto exit;
811 	}
812 
813 	goto usbtmc_clear_check_status;
814 
815 usbtmc_clear_bulk_out_halt:
816 
817 	rv = usb_clear_halt(data->usb_dev,
818 			    usb_sndbulkpipe(data->usb_dev, data->bulk_out));
819 	if (rv < 0) {
820 		dev_err(dev, "usb_control_msg returned %d\n", rv);
821 		goto exit;
822 	}
823 	rv = 0;
824 
825 exit:
826 	kfree(buffer);
827 	return rv;
828 }
829 
830 static int usbtmc_ioctl_clear_out_halt(struct usbtmc_device_data *data)
831 {
832 	int rv;
833 
834 	rv = usb_clear_halt(data->usb_dev,
835 			    usb_sndbulkpipe(data->usb_dev, data->bulk_out));
836 
837 	if (rv < 0) {
838 		dev_err(&data->usb_dev->dev, "usb_control_msg returned %d\n",
839 			rv);
840 		return rv;
841 	}
842 	return 0;
843 }
844 
845 static int usbtmc_ioctl_clear_in_halt(struct usbtmc_device_data *data)
846 {
847 	int rv;
848 
849 	rv = usb_clear_halt(data->usb_dev,
850 			    usb_rcvbulkpipe(data->usb_dev, data->bulk_in));
851 
852 	if (rv < 0) {
853 		dev_err(&data->usb_dev->dev, "usb_control_msg returned %d\n",
854 			rv);
855 		return rv;
856 	}
857 	return 0;
858 }
859 
860 static int get_capabilities(struct usbtmc_device_data *data)
861 {
862 	struct device *dev = &data->usb_dev->dev;
863 	char *buffer;
864 	int rv = 0;
865 
866 	buffer = kmalloc(0x18, GFP_KERNEL);
867 	if (!buffer)
868 		return -ENOMEM;
869 
870 	rv = usb_control_msg(data->usb_dev, usb_rcvctrlpipe(data->usb_dev, 0),
871 			     USBTMC_REQUEST_GET_CAPABILITIES,
872 			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
873 			     0, 0, buffer, 0x18, USBTMC_TIMEOUT);
874 	if (rv < 0) {
875 		dev_err(dev, "usb_control_msg returned %d\n", rv);
876 		goto err_out;
877 	}
878 
879 	dev_dbg(dev, "GET_CAPABILITIES returned %x\n", buffer[0]);
880 	if (buffer[0] != USBTMC_STATUS_SUCCESS) {
881 		dev_err(dev, "GET_CAPABILITIES returned %x\n", buffer[0]);
882 		rv = -EPERM;
883 		goto err_out;
884 	}
885 	dev_dbg(dev, "Interface capabilities are %x\n", buffer[4]);
886 	dev_dbg(dev, "Device capabilities are %x\n", buffer[5]);
887 	dev_dbg(dev, "USB488 interface capabilities are %x\n", buffer[14]);
888 	dev_dbg(dev, "USB488 device capabilities are %x\n", buffer[15]);
889 
890 	data->capabilities.interface_capabilities = buffer[4];
891 	data->capabilities.device_capabilities = buffer[5];
892 	data->capabilities.usb488_interface_capabilities = buffer[14];
893 	data->capabilities.usb488_device_capabilities = buffer[15];
894 	rv = 0;
895 
896 err_out:
897 	kfree(buffer);
898 	return rv;
899 }
900 
901 #define capability_attribute(name)					\
902 static ssize_t name##_show(struct device *dev,				\
903 			   struct device_attribute *attr, char *buf)	\
904 {									\
905 	struct usb_interface *intf = to_usb_interface(dev);		\
906 	struct usbtmc_device_data *data = usb_get_intfdata(intf);	\
907 									\
908 	return sprintf(buf, "%d\n", data->capabilities.name);		\
909 }									\
910 static DEVICE_ATTR_RO(name)
911 
912 capability_attribute(interface_capabilities);
913 capability_attribute(device_capabilities);
914 capability_attribute(usb488_interface_capabilities);
915 capability_attribute(usb488_device_capabilities);
916 
917 static struct attribute *capability_attrs[] = {
918 	&dev_attr_interface_capabilities.attr,
919 	&dev_attr_device_capabilities.attr,
920 	&dev_attr_usb488_interface_capabilities.attr,
921 	&dev_attr_usb488_device_capabilities.attr,
922 	NULL,
923 };
924 
925 static struct attribute_group capability_attr_grp = {
926 	.attrs = capability_attrs,
927 };
928 
929 static ssize_t TermChar_show(struct device *dev,
930 			     struct device_attribute *attr, char *buf)
931 {
932 	struct usb_interface *intf = to_usb_interface(dev);
933 	struct usbtmc_device_data *data = usb_get_intfdata(intf);
934 
935 	return sprintf(buf, "%c\n", data->TermChar);
936 }
937 
938 static ssize_t TermChar_store(struct device *dev,
939 			      struct device_attribute *attr,
940 			      const char *buf, size_t count)
941 {
942 	struct usb_interface *intf = to_usb_interface(dev);
943 	struct usbtmc_device_data *data = usb_get_intfdata(intf);
944 
945 	if (count < 1)
946 		return -EINVAL;
947 	data->TermChar = buf[0];
948 	return count;
949 }
950 static DEVICE_ATTR_RW(TermChar);
951 
952 #define data_attribute(name)						\
953 static ssize_t name##_show(struct device *dev,				\
954 			   struct device_attribute *attr, char *buf)	\
955 {									\
956 	struct usb_interface *intf = to_usb_interface(dev);		\
957 	struct usbtmc_device_data *data = usb_get_intfdata(intf);	\
958 									\
959 	return sprintf(buf, "%d\n", data->name);			\
960 }									\
961 static ssize_t name##_store(struct device *dev,				\
962 			    struct device_attribute *attr,		\
963 			    const char *buf, size_t count)		\
964 {									\
965 	struct usb_interface *intf = to_usb_interface(dev);		\
966 	struct usbtmc_device_data *data = usb_get_intfdata(intf);	\
967 	ssize_t result;							\
968 	unsigned val;							\
969 									\
970 	result = sscanf(buf, "%u\n", &val);				\
971 	if (result != 1)						\
972 		result = -EINVAL;					\
973 	data->name = val;						\
974 	if (result < 0)							\
975 		return result;						\
976 	else								\
977 		return count;						\
978 }									\
979 static DEVICE_ATTR_RW(name)
980 
981 data_attribute(TermCharEnabled);
982 data_attribute(auto_abort);
983 
984 static struct attribute *data_attrs[] = {
985 	&dev_attr_TermChar.attr,
986 	&dev_attr_TermCharEnabled.attr,
987 	&dev_attr_auto_abort.attr,
988 	NULL,
989 };
990 
991 static struct attribute_group data_attr_grp = {
992 	.attrs = data_attrs,
993 };
994 
995 static int usbtmc_ioctl_indicator_pulse(struct usbtmc_device_data *data)
996 {
997 	struct device *dev;
998 	u8 *buffer;
999 	int rv;
1000 
1001 	dev = &data->intf->dev;
1002 
1003 	buffer = kmalloc(2, GFP_KERNEL);
1004 	if (!buffer)
1005 		return -ENOMEM;
1006 
1007 	rv = usb_control_msg(data->usb_dev,
1008 			     usb_rcvctrlpipe(data->usb_dev, 0),
1009 			     USBTMC_REQUEST_INDICATOR_PULSE,
1010 			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
1011 			     0, 0, buffer, 0x01, USBTMC_TIMEOUT);
1012 
1013 	if (rv < 0) {
1014 		dev_err(dev, "usb_control_msg returned %d\n", rv);
1015 		goto exit;
1016 	}
1017 
1018 	dev_dbg(dev, "INDICATOR_PULSE returned %x\n", buffer[0]);
1019 
1020 	if (buffer[0] != USBTMC_STATUS_SUCCESS) {
1021 		dev_err(dev, "INDICATOR_PULSE returned %x\n", buffer[0]);
1022 		rv = -EPERM;
1023 		goto exit;
1024 	}
1025 	rv = 0;
1026 
1027 exit:
1028 	kfree(buffer);
1029 	return rv;
1030 }
1031 
1032 static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1033 {
1034 	struct usbtmc_device_data *data;
1035 	int retval = -EBADRQC;
1036 
1037 	data = file->private_data;
1038 	mutex_lock(&data->io_mutex);
1039 	if (data->zombie) {
1040 		retval = -ENODEV;
1041 		goto skip_io_on_zombie;
1042 	}
1043 
1044 	switch (cmd) {
1045 	case USBTMC_IOCTL_CLEAR_OUT_HALT:
1046 		retval = usbtmc_ioctl_clear_out_halt(data);
1047 		break;
1048 
1049 	case USBTMC_IOCTL_CLEAR_IN_HALT:
1050 		retval = usbtmc_ioctl_clear_in_halt(data);
1051 		break;
1052 
1053 	case USBTMC_IOCTL_INDICATOR_PULSE:
1054 		retval = usbtmc_ioctl_indicator_pulse(data);
1055 		break;
1056 
1057 	case USBTMC_IOCTL_CLEAR:
1058 		retval = usbtmc_ioctl_clear(data);
1059 		break;
1060 
1061 	case USBTMC_IOCTL_ABORT_BULK_OUT:
1062 		retval = usbtmc_ioctl_abort_bulk_out(data);
1063 		break;
1064 
1065 	case USBTMC_IOCTL_ABORT_BULK_IN:
1066 		retval = usbtmc_ioctl_abort_bulk_in(data);
1067 		break;
1068 	}
1069 
1070 skip_io_on_zombie:
1071 	mutex_unlock(&data->io_mutex);
1072 	return retval;
1073 }
1074 
1075 static const struct file_operations fops = {
1076 	.owner		= THIS_MODULE,
1077 	.read		= usbtmc_read,
1078 	.write		= usbtmc_write,
1079 	.open		= usbtmc_open,
1080 	.release	= usbtmc_release,
1081 	.unlocked_ioctl	= usbtmc_ioctl,
1082 	.llseek		= default_llseek,
1083 };
1084 
1085 static struct usb_class_driver usbtmc_class = {
1086 	.name =		"usbtmc%d",
1087 	.fops =		&fops,
1088 	.minor_base =	USBTMC_MINOR_BASE,
1089 };
1090 
1091 
1092 static int usbtmc_probe(struct usb_interface *intf,
1093 			const struct usb_device_id *id)
1094 {
1095 	struct usbtmc_device_data *data;
1096 	struct usb_host_interface *iface_desc;
1097 	struct usb_endpoint_descriptor *endpoint;
1098 	int n;
1099 	int retcode;
1100 
1101 	dev_dbg(&intf->dev, "%s called\n", __func__);
1102 
1103 	data = devm_kzalloc(&intf->dev, sizeof(*data), GFP_KERNEL);
1104 	if (!data) {
1105 		dev_err(&intf->dev, "Unable to allocate kernel memory\n");
1106 		return -ENOMEM;
1107 	}
1108 
1109 	data->intf = intf;
1110 	data->id = id;
1111 	data->usb_dev = usb_get_dev(interface_to_usbdev(intf));
1112 	usb_set_intfdata(intf, data);
1113 	kref_init(&data->kref);
1114 	mutex_init(&data->io_mutex);
1115 	data->zombie = 0;
1116 
1117 	/* Determine if it is a Rigol or not */
1118 	data->rigol_quirk = 0;
1119 	dev_dbg(&intf->dev, "Trying to find if device Vendor 0x%04X Product 0x%04X has the RIGOL quirk\n",
1120 		le16_to_cpu(data->usb_dev->descriptor.idVendor),
1121 		le16_to_cpu(data->usb_dev->descriptor.idProduct));
1122 	for(n = 0; usbtmc_id_quirk[n].idVendor > 0; n++) {
1123 		if ((usbtmc_id_quirk[n].idVendor == le16_to_cpu(data->usb_dev->descriptor.idVendor)) &&
1124 		    (usbtmc_id_quirk[n].idProduct == le16_to_cpu(data->usb_dev->descriptor.idProduct))) {
1125 			dev_dbg(&intf->dev, "Setting this device as having the RIGOL quirk\n");
1126 			data->rigol_quirk = 1;
1127 			break;
1128 		}
1129 	}
1130 
1131 	/* Initialize USBTMC bTag and other fields */
1132 	data->bTag	= 1;
1133 	data->TermCharEnabled = 0;
1134 	data->TermChar = '\n';
1135 
1136 	/* USBTMC devices have only one setting, so use that */
1137 	iface_desc = data->intf->cur_altsetting;
1138 
1139 	/* Find bulk in endpoint */
1140 	for (n = 0; n < iface_desc->desc.bNumEndpoints; n++) {
1141 		endpoint = &iface_desc->endpoint[n].desc;
1142 
1143 		if (usb_endpoint_is_bulk_in(endpoint)) {
1144 			data->bulk_in = endpoint->bEndpointAddress;
1145 			dev_dbg(&intf->dev, "Found bulk in endpoint at %u\n",
1146 				data->bulk_in);
1147 			break;
1148 		}
1149 	}
1150 
1151 	/* Find bulk out endpoint */
1152 	for (n = 0; n < iface_desc->desc.bNumEndpoints; n++) {
1153 		endpoint = &iface_desc->endpoint[n].desc;
1154 
1155 		if (usb_endpoint_is_bulk_out(endpoint)) {
1156 			data->bulk_out = endpoint->bEndpointAddress;
1157 			dev_dbg(&intf->dev, "Found Bulk out endpoint at %u\n",
1158 				data->bulk_out);
1159 			break;
1160 		}
1161 	}
1162 
1163 	retcode = get_capabilities(data);
1164 	if (retcode)
1165 		dev_err(&intf->dev, "can't read capabilities\n");
1166 	else
1167 		retcode = sysfs_create_group(&intf->dev.kobj,
1168 					     &capability_attr_grp);
1169 
1170 	retcode = sysfs_create_group(&intf->dev.kobj, &data_attr_grp);
1171 
1172 	retcode = usb_register_dev(intf, &usbtmc_class);
1173 	if (retcode) {
1174 		dev_err(&intf->dev, "Not able to get a minor"
1175 			" (base %u, slice default): %d\n", USBTMC_MINOR_BASE,
1176 			retcode);
1177 		goto error_register;
1178 	}
1179 	dev_dbg(&intf->dev, "Using minor number %d\n", intf->minor);
1180 
1181 	return 0;
1182 
1183 error_register:
1184 	sysfs_remove_group(&intf->dev.kobj, &capability_attr_grp);
1185 	sysfs_remove_group(&intf->dev.kobj, &data_attr_grp);
1186 	kref_put(&data->kref, usbtmc_delete);
1187 	return retcode;
1188 }
1189 
1190 static void usbtmc_disconnect(struct usb_interface *intf)
1191 {
1192 	struct usbtmc_device_data *data;
1193 
1194 	dev_dbg(&intf->dev, "usbtmc_disconnect called\n");
1195 
1196 	data = usb_get_intfdata(intf);
1197 	usb_deregister_dev(intf, &usbtmc_class);
1198 	sysfs_remove_group(&intf->dev.kobj, &capability_attr_grp);
1199 	sysfs_remove_group(&intf->dev.kobj, &data_attr_grp);
1200 	mutex_lock(&data->io_mutex);
1201 	data->zombie = 1;
1202 	mutex_unlock(&data->io_mutex);
1203 	kref_put(&data->kref, usbtmc_delete);
1204 }
1205 
1206 static int usbtmc_suspend(struct usb_interface *intf, pm_message_t message)
1207 {
1208 	/* this driver does not have pending URBs */
1209 	return 0;
1210 }
1211 
1212 static int usbtmc_resume(struct usb_interface *intf)
1213 {
1214 	return 0;
1215 }
1216 
1217 static struct usb_driver usbtmc_driver = {
1218 	.name		= "usbtmc",
1219 	.id_table	= usbtmc_devices,
1220 	.probe		= usbtmc_probe,
1221 	.disconnect	= usbtmc_disconnect,
1222 	.suspend	= usbtmc_suspend,
1223 	.resume		= usbtmc_resume,
1224 };
1225 
1226 module_usb_driver(usbtmc_driver);
1227 
1228 MODULE_LICENSE("GPL");
1229