Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  1 /**
  2  * drivers/usb/class/usbtmc.c - USB Test & Measurment 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 #include <linux/init.h>
 23 #include <linux/module.h>
 24 #include <linux/kernel.h>
 25 #include <linux/fs.h>
 26 #include <linux/uaccess.h>
 27 #include <linux/kref.h>
 28 #include <linux/mutex.h>
 29 #include <linux/usb.h>
 30 #include <linux/usb/tmc.h>
 31 
 32 
 33 #define USBTMC_MINOR_BASE       176
 34 
 35 /*
 36  * Size of driver internal IO buffer. Must be multiple of 4 and at least as
 37  * large as wMaxPacketSize (which is usually 512 bytes).
 38  */
 39 #define USBTMC_SIZE_IOBUFFER    2048
 40 
 41 /* Default USB timeout (in milliseconds) */
 42 #define USBTMC_TIMEOUT          10
 43 
 44 /*
 45  * Maximum number of read cycles to empty bulk in endpoint during CLEAR and
 46  * ABORT_BULK_IN requests. Ends the loop if (for whatever reason) a short
 47  * packet is never read.
 48  */
 49 #define USBTMC_MAX_READS_TO_CLEAR_BULK_IN       100
 50 
 51 static struct usb_device_id usbtmc_devices[] = {
 52         { USB_INTERFACE_INFO(USB_CLASS_APP_SPEC, 3, 0), },
 53         { USB_INTERFACE_INFO(USB_CLASS_APP_SPEC, 3, 1), },
 54         { 0, } /* terminating entry */
 55 };
 56 MODULE_DEVICE_TABLE(usb, usbtmc_devices);
 57 
 58 /*
 59  * This structure is the capabilities for the device
 60  * See section 4.2.1.8 of the USBTMC specification for details.
 61  */
 62 struct usbtmc_dev_capabilities {
 63         __u8 interface_capabilities;
 64         __u8 device_capabilities;
 65         __u8 usb488_interface_capabilities;
 66         __u8 usb488_device_capabilities;
 67 };
 68 
 69 /* This structure holds private data for each USBTMC device. One copy is
 70  * allocated for each USBTMC device in the driver's probe function.
 71  */
 72 struct usbtmc_device_data {
 73         const struct usb_device_id *id;
 74         struct usb_device *usb_dev;
 75         struct usb_interface *intf;
 76 
 77         unsigned int bulk_in;
 78         unsigned int bulk_out;
 79 
 80         u8 bTag;
 81         u8 bTag_last_write;     /* needed for abort */
 82         u8 bTag_last_read;      /* needed for abort */
 83 
 84         /* attributes from the USB TMC spec for this device */
 85         u8 TermChar;
 86         bool TermCharEnabled;
 87         bool auto_abort;
 88 
 89         struct usbtmc_dev_capabilities  capabilities;
 90         struct kref kref;
 91         struct mutex io_mutex;  /* only one i/o function running at a time */
 92 };
 93 #define to_usbtmc_data(d) container_of(d, struct usbtmc_device_data, kref)
 94 
 95 /* Forward declarations */
 96 static struct usb_driver usbtmc_driver;
 97 
 98 static void usbtmc_delete(struct kref *kref)
 99 {
100         struct usbtmc_device_data *data = to_usbtmc_data(kref);
101 
102         usb_put_dev(data->usb_dev);
103         kfree(data);
104 }
105 
106 static int usbtmc_open(struct inode *inode, struct file *filp)
107 {
108         struct usb_interface *intf;
109         struct usbtmc_device_data *data;
110         int retval = 0;
111 
112         intf = usb_find_interface(&usbtmc_driver, iminor(inode));
113         if (!intf) {
114                 printk(KERN_ERR KBUILD_MODNAME
115                        ": can not find device for minor %d", iminor(inode));
116                 retval = -ENODEV;
117                 goto exit;
118         }
119 
120         data = usb_get_intfdata(intf);
121         kref_get(&data->kref);
122 
123         /* Store pointer in file structure's private data field */
124         filp->private_data = data;
125 
126 exit:
127         return retval;
128 }
129 
130 static int usbtmc_release(struct inode *inode, struct file *file)
131 {
132         struct usbtmc_device_data *data = file->private_data;
133 
134         kref_put(&data->kref, usbtmc_delete);
135         return 0;
136 }
137 
138 static int usbtmc_ioctl_abort_bulk_in(struct usbtmc_device_data *data)
139 {
140         u8 *buffer;
141         struct device *dev;
142         int rv;
143         int n;
144         int actual;
145         struct usb_host_interface *current_setting;
146         int max_size;
147 
148         dev = &data->intf->dev;
149         buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
150         if (!buffer)
151                 return -ENOMEM;
152 
153         rv = usb_control_msg(data->usb_dev,
154                              usb_rcvctrlpipe(data->usb_dev, 0),
155                              USBTMC_REQUEST_INITIATE_ABORT_BULK_IN,
156                              USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
157                              data->bTag_last_read, data->bulk_in,
158                              buffer, 2, USBTMC_TIMEOUT);
159 
160         if (rv < 0) {
161                 dev_err(dev, "usb_control_msg returned %d\n", rv);
162                 goto exit;
163         }
164 
165         dev_dbg(dev, "INITIATE_ABORT_BULK_IN returned %x\n", buffer[0]);
166 
167         if (buffer[0] == USBTMC_STATUS_FAILED) {
168                 rv = 0;
169                 goto exit;
170         }
171 
172         if (buffer[0] != USBTMC_STATUS_SUCCESS) {
173                 dev_err(dev, "INITIATE_ABORT_BULK_IN returned %x\n",
174                         buffer[0]);
175                 rv = -EPERM;
176                 goto exit;
177         }
178 
179         max_size = 0;
180         current_setting = data->intf->cur_altsetting;
181         for (n = 0; n < current_setting->desc.bNumEndpoints; n++)
182                 if (current_setting->endpoint[n].desc.bEndpointAddress ==
183                         data->bulk_in)
184                         max_size = le16_to_cpu(current_setting->endpoint[n].
185                                                 desc.wMaxPacketSize);
186 
187         if (max_size == 0) {
188                 dev_err(dev, "Couldn't get wMaxPacketSize\n");
189                 rv = -EPERM;
190                 goto exit;
191         }
192 
193         dev_dbg(&data->intf->dev, "wMaxPacketSize is %d\n", max_size);
194 
195         n = 0;
196 
197         do {
198                 dev_dbg(dev, "Reading from bulk in EP\n");
199 
200                 rv = usb_bulk_msg(data->usb_dev,
201                                   usb_rcvbulkpipe(data->usb_dev,
202                                                   data->bulk_in),
203                                   buffer, USBTMC_SIZE_IOBUFFER,
204                                   &actual, USBTMC_TIMEOUT);
205 
206                 n++;
207 
208                 if (rv < 0) {
209                         dev_err(dev, "usb_bulk_msg returned %d\n", rv);
210                         goto exit;
211                 }
212         } while ((actual == max_size) &&
213                  (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
214 
215         if (actual == max_size) {
216                 dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
217                         USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
218                 rv = -EPERM;
219                 goto exit;
220         }
221 
222         n = 0;
223 
224 usbtmc_abort_bulk_in_status:
225         rv = usb_control_msg(data->usb_dev,
226                              usb_rcvctrlpipe(data->usb_dev, 0),
227                              USBTMC_REQUEST_CHECK_ABORT_BULK_IN_STATUS,
228                              USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
229                              0, data->bulk_in, buffer, 0x08,
230                              USBTMC_TIMEOUT);
231 
232         if (rv < 0) {
233                 dev_err(dev, "usb_control_msg returned %d\n", rv);
234                 goto exit;
235         }
236 
237         dev_dbg(dev, "INITIATE_ABORT_BULK_IN returned %x\n", buffer[0]);
238 
239         if (buffer[0] == USBTMC_STATUS_SUCCESS) {
240                 rv = 0;
241                 goto exit;
242         }
243 
244         if (buffer[0] != USBTMC_STATUS_PENDING) {
245                 dev_err(dev, "INITIATE_ABORT_BULK_IN returned %x\n", buffer[0]);
246                 rv = -EPERM;
247                 goto exit;
248         }
249 
250         if (buffer[1] == 1)
251                 do {
252                         dev_dbg(dev, "Reading from bulk in EP\n");
253 
254                         rv = usb_bulk_msg(data->usb_dev,
255                                           usb_rcvbulkpipe(data->usb_dev,
256                                                           data->bulk_in),
257                                           buffer, USBTMC_SIZE_IOBUFFER,
258                                           &actual, USBTMC_TIMEOUT);
259 
260                         n++;
261 
262                         if (rv < 0) {
263                                 dev_err(dev, "usb_bulk_msg returned %d\n", rv);
264                                 goto exit;
265                         }
266                 } while ((actual = max_size) &&
267                          (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
268 
269         if (actual == max_size) {
270                 dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
271                         USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
272                 rv = -EPERM;
273                 goto exit;
274         }
275 
276         goto usbtmc_abort_bulk_in_status;
277 
278 exit:
279         kfree(buffer);
280         return rv;
281 
282 }
283 
284 static int usbtmc_ioctl_abort_bulk_out(struct usbtmc_device_data *data)
285 {
286         struct device *dev;
287         u8 *buffer;
288         int rv;
289         int n;
290 
291         dev = &data->intf->dev;
292 
293         buffer = kmalloc(8, GFP_KERNEL);
294         if (!buffer)
295                 return -ENOMEM;
296 
297         rv = usb_control_msg(data->usb_dev,
298                              usb_rcvctrlpipe(data->usb_dev, 0),
299                              USBTMC_REQUEST_INITIATE_ABORT_BULK_OUT,
300                              USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
301                              data->bTag_last_write, data->bulk_out,
302                              buffer, 2, USBTMC_TIMEOUT);
303 
304         if (rv < 0) {
305                 dev_err(dev, "usb_control_msg returned %d\n", rv);
306                 goto exit;
307         }
308 
309         dev_dbg(dev, "INITIATE_ABORT_BULK_OUT returned %x\n", buffer[0]);
310 
311         if (buffer[0] != USBTMC_STATUS_SUCCESS) {
312                 dev_err(dev, "INITIATE_ABORT_BULK_OUT returned %x\n",
313                         buffer[0]);
314                 rv = -EPERM;
315                 goto exit;
316         }
317 
318         n = 0;
319 
320 usbtmc_abort_bulk_out_check_status:
321         rv = usb_control_msg(data->usb_dev,
322                              usb_rcvctrlpipe(data->usb_dev, 0),
323                              USBTMC_REQUEST_CHECK_ABORT_BULK_OUT_STATUS,
324                              USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
325                              0, data->bulk_out, buffer, 0x08,
326                              USBTMC_TIMEOUT);
327         n++;
328         if (rv < 0) {
329                 dev_err(dev, "usb_control_msg returned %d\n", rv);
330                 goto exit;
331         }
332 
333         dev_dbg(dev, "CHECK_ABORT_BULK_OUT returned %x\n", buffer[0]);
334 
335         if (buffer[0] == USBTMC_STATUS_SUCCESS)
336                 goto usbtmc_abort_bulk_out_clear_halt;
337 
338         if ((buffer[0] == USBTMC_STATUS_PENDING) &&
339             (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN))
340                 goto usbtmc_abort_bulk_out_check_status;
341 
342         rv = -EPERM;
343         goto exit;
344 
345 usbtmc_abort_bulk_out_clear_halt:
346         rv = usb_control_msg(data->usb_dev,
347                              usb_sndctrlpipe(data->usb_dev, 0),
348                              USB_REQ_CLEAR_FEATURE,
349                              USB_DIR_OUT | USB_TYPE_STANDARD |
350                              USB_RECIP_ENDPOINT,
351                              USB_ENDPOINT_HALT, data->bulk_out, buffer,
352                              0, USBTMC_TIMEOUT);
353 
354         if (rv < 0) {
355                 dev_err(dev, "usb_control_msg returned %d\n", rv);
356                 goto exit;
357         }
358         rv = 0;
359 
360 exit:
361         kfree(buffer);
362         return rv;
363 }
364 
365 static ssize_t usbtmc_read(struct file *filp, char __user *buf,
366                            size_t count, loff_t *f_pos)
367 {
368         struct usbtmc_device_data *data;
369         struct device *dev;
370         u32 n_characters;
371         u8 *buffer;
372         int actual;
373         size_t done;
374         size_t remaining;
375         int retval;
376         size_t this_part;
377 
378         /* Get pointer to private data structure */
379         data = filp->private_data;
380         dev = &data->intf->dev;
381 
382         buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
383         if (!buffer)
384                 return -ENOMEM;
385 
386         mutex_lock(&data->io_mutex);
387 
388         remaining = count;
389         done = 0;
390 
391         while (remaining > 0) {
392                 if (remaining > USBTMC_SIZE_IOBUFFER - 12 - 3)
393                         this_part = USBTMC_SIZE_IOBUFFER - 12 - 3;
394                 else
395                         this_part = remaining;
396 
397                 /* Setup IO buffer for DEV_DEP_MSG_IN message
398                  * Refer to class specs for details
399                  */
400                 buffer[0] = 2;
401                 buffer[1] = data->bTag;
402                 buffer[2] = ~(data->bTag);
403                 buffer[3] = 0; /* Reserved */
404                 buffer[4] = (this_part - 12 - 3) & 255;
405                 buffer[5] = ((this_part - 12 - 3) >> 8) & 255;
406                 buffer[6] = ((this_part - 12 - 3) >> 16) & 255;
407                 buffer[7] = ((this_part - 12 - 3) >> 24) & 255;
408                 buffer[8] = data->TermCharEnabled * 2;
409                 /* Use term character? */
410                 buffer[9] = data->TermChar;
411                 buffer[10] = 0; /* Reserved */
412                 buffer[11] = 0; /* Reserved */
413 
414                 /* Send bulk URB */
415                 retval = usb_bulk_msg(data->usb_dev,
416                                       usb_sndbulkpipe(data->usb_dev,
417                                                       data->bulk_out),
418                                       buffer, 12, &actual, USBTMC_TIMEOUT);
419 
420                 /* Store bTag (in case we need to abort) */
421                 data->bTag_last_write = data->bTag;
422 
423                 /* Increment bTag -- and increment again if zero */
424                 data->bTag++;
425                 if (!data->bTag)
426                         (data->bTag)++;
427 
428                 if (retval < 0) {
429                         dev_err(dev, "usb_bulk_msg returned %d\n", retval);
430                         if (data->auto_abort)
431                                 usbtmc_ioctl_abort_bulk_out(data);
432                         goto exit;
433                 }
434 
435                 /* Send bulk URB */
436                 retval = usb_bulk_msg(data->usb_dev,
437                                       usb_rcvbulkpipe(data->usb_dev,
438                                                       data->bulk_in),
439                                       buffer, USBTMC_SIZE_IOBUFFER, &actual,
440                                       USBTMC_TIMEOUT);
441 
442                 /* Store bTag (in case we need to abort) */
443                 data->bTag_last_read = data->bTag;
444 
445                 if (retval < 0) {
446                         dev_err(dev, "Unable to read data, error %d\n", retval);
447                         if (data->auto_abort)
448                                 usbtmc_ioctl_abort_bulk_in(data);
449                         goto exit;
450                 }
451 
452                 /* How many characters did the instrument send? */
453                 n_characters = buffer[4] +
454                                (buffer[5] << 8) +
455                                (buffer[6] << 16) +
456                                (buffer[7] << 24);
457 
458                 /* Ensure the instrument doesn't lie about it */
459                 if(n_characters > actual - 12) {
460                         dev_err(dev, "Device lies about message size: %zu > %zu\n", n_characters, actual - 12);
461                         n_characters = actual - 12;
462                 }
463 
464                 /* Ensure the instrument doesn't send more back than requested */
465                 if(n_characters > this_part) {
466                         dev_err(dev, "Device returns more than requested: %zu > %zu\n", done + n_characters, done + this_part);
467                         n_characters = this_part;
468                 }
469 
470                 /* Copy buffer to user space */
471                 if (copy_to_user(buf + done, &buffer[12], n_characters)) {
472                         /* There must have been an addressing problem */
473                         retval = -EFAULT;
474                         goto exit;
475                 }
476 
477                 done += n_characters;
478                 if (n_characters < USBTMC_SIZE_IOBUFFER)
479                         remaining = 0;
480                 else
481                         remaining -= n_characters;
482         }
483 
484         /* Update file position value */
485         *f_pos = *f_pos + done;
486         retval = done;
487 
488 exit:
489         mutex_unlock(&data->io_mutex);
490         kfree(buffer);
491         return retval;
492 }
493 
494 static ssize_t usbtmc_write(struct file *filp, const char __user *buf,
495                             size_t count, loff_t *f_pos)
496 {
497         struct usbtmc_device_data *data;
498         u8 *buffer;
499         int retval;
500         int actual;
501         unsigned long int n_bytes;
502         int remaining;
503         int done;
504         int this_part;
505 
506         data = filp->private_data;
507 
508         buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
509         if (!buffer)
510                 return -ENOMEM;
511 
512         mutex_lock(&data->io_mutex);
513 
514         remaining = count;
515         done = 0;
516 
517         while (remaining > 0) {
518                 if (remaining > USBTMC_SIZE_IOBUFFER - 12) {
519                         this_part = USBTMC_SIZE_IOBUFFER - 12;
520                         buffer[8] = 0;
521                 } else {
522                         this_part = remaining;
523                         buffer[8] = 1;
524                 }
525 
526                 /* Setup IO buffer for DEV_DEP_MSG_OUT message */
527                 buffer[0] = 1;
528                 buffer[1] = data->bTag;
529                 buffer[2] = ~(data->bTag);
530                 buffer[3] = 0; /* Reserved */
531                 buffer[4] = this_part & 255;
532                 buffer[5] = (this_part >> 8) & 255;
533                 buffer[6] = (this_part >> 16) & 255;
534                 buffer[7] = (this_part >> 24) & 255;
535                 /* buffer[8] is set above... */
536                 buffer[9] = 0; /* Reserved */
537                 buffer[10] = 0; /* Reserved */
538                 buffer[11] = 0; /* Reserved */
539 
540                 if (copy_from_user(&buffer[12], buf + done, this_part)) {
541                         retval = -EFAULT;
542                         goto exit;
543                 }
544 
545                 n_bytes = roundup(12 + this_part, 4);
546                 memset(buffer + 12 + this_part, 0, n_bytes - (12 + this_part));
547 
548                 do {
549                         retval = usb_bulk_msg(data->usb_dev,
550                                               usb_sndbulkpipe(data->usb_dev,
551                                                               data->bulk_out),
552                                               buffer, n_bytes,
553                                               &actual, USBTMC_TIMEOUT);
554                         if (retval != 0)
555                                 break;
556                         n_bytes -= actual;
557                 } while (n_bytes);
558 
559                 data->bTag_last_write = data->bTag;
560                 data->bTag++;
561 
562                 if (!data->bTag)
563                         data->bTag++;
564 
565                 if (retval < 0) {
566                         dev_err(&data->intf->dev,
567                                 "Unable to send data, error %d\n", retval);
568                         if (data->auto_abort)
569                                 usbtmc_ioctl_abort_bulk_out(data);
570                         goto exit;
571                 }
572 
573                 remaining -= this_part;
574                 done += this_part;
575         }
576 
577         retval = count;
578 exit:
579         mutex_unlock(&data->io_mutex);
580         kfree(buffer);
581         return retval;
582 }
583 
584 static int usbtmc_ioctl_clear(struct usbtmc_device_data *data)
585 {
586         struct usb_host_interface *current_setting;
587         struct usb_endpoint_descriptor *desc;
588         struct device *dev;
589         u8 *buffer;
590         int rv;
591         int n;
592         int actual;
593         int max_size;
594 
595         dev = &data->intf->dev;
596 
597         dev_dbg(dev, "Sending INITIATE_CLEAR request\n");
598 
599         buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
600         if (!buffer)
601                 return -ENOMEM;
602 
603         rv = usb_control_msg(data->usb_dev,
604                              usb_rcvctrlpipe(data->usb_dev, 0),
605                              USBTMC_REQUEST_INITIATE_CLEAR,
606                              USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
607                              0, 0, buffer, 1, USBTMC_TIMEOUT);
608         if (rv < 0) {
609                 dev_err(dev, "usb_control_msg returned %d\n", rv);
610                 goto exit;
611         }
612 
613         dev_dbg(dev, "INITIATE_CLEAR returned %x\n", buffer[0]);
614 
615         if (buffer[0] != USBTMC_STATUS_SUCCESS) {
616                 dev_err(dev, "INITIATE_CLEAR returned %x\n", buffer[0]);
617                 rv = -EPERM;
618                 goto exit;
619         }
620 
621         max_size = 0;
622         current_setting = data->intf->cur_altsetting;
623         for (n = 0; n < current_setting->desc.bNumEndpoints; n++) {
624                 desc = &current_setting->endpoint[n].desc;
625                 if (desc->bEndpointAddress == data->bulk_in)
626                         max_size = le16_to_cpu(desc->wMaxPacketSize);
627         }
628 
629         if (max_size == 0) {
630                 dev_err(dev, "Couldn't get wMaxPacketSize\n");
631                 rv = -EPERM;
632                 goto exit;
633         }
634 
635         dev_dbg(dev, "wMaxPacketSize is %d\n", max_size);
636 
637         n = 0;
638 
639 usbtmc_clear_check_status:
640 
641         dev_dbg(dev, "Sending CHECK_CLEAR_STATUS request\n");
642 
643         rv = usb_control_msg(data->usb_dev,
644                              usb_rcvctrlpipe(data->usb_dev, 0),
645                              USBTMC_REQUEST_CHECK_CLEAR_STATUS,
646                              USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
647                              0, 0, buffer, 2, USBTMC_TIMEOUT);
648         if (rv < 0) {
649                 dev_err(dev, "usb_control_msg returned %d\n", rv);
650                 goto exit;
651         }
652 
653         dev_dbg(dev, "CHECK_CLEAR_STATUS returned %x\n", buffer[0]);
654 
655         if (buffer[0] == USBTMC_STATUS_SUCCESS)
656                 goto usbtmc_clear_bulk_out_halt;
657 
658         if (buffer[0] != USBTMC_STATUS_PENDING) {
659                 dev_err(dev, "CHECK_CLEAR_STATUS returned %x\n", buffer[0]);
660                 rv = -EPERM;
661                 goto exit;
662         }
663 
664         if (buffer[1] == 1)
665                 do {
666                         dev_dbg(dev, "Reading from bulk in EP\n");
667 
668                         rv = usb_bulk_msg(data->usb_dev,
669                                           usb_rcvbulkpipe(data->usb_dev,
670                                                           data->bulk_in),
671                                           buffer, USBTMC_SIZE_IOBUFFER,
672                                           &actual, USBTMC_TIMEOUT);
673                         n++;
674 
675                         if (rv < 0) {
676                                 dev_err(dev, "usb_control_msg returned %d\n",
677                                         rv);
678                                 goto exit;
679                         }
680                 } while ((actual == max_size) &&
681                           (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
682 
683         if (actual == max_size) {
684                 dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
685                         USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
686                 rv = -EPERM;
687                 goto exit;
688         }
689 
690         goto usbtmc_clear_check_status;
691 
692 usbtmc_clear_bulk_out_halt:
693 
694         rv = usb_control_msg(data->usb_dev,
695                              usb_sndctrlpipe(data->usb_dev, 0),
696                              USB_REQ_CLEAR_FEATURE,
697                              USB_DIR_OUT | USB_TYPE_STANDARD |
698                              USB_RECIP_ENDPOINT,
699                              USB_ENDPOINT_HALT,
700                              data->bulk_out, buffer, 0,
701                              USBTMC_TIMEOUT);
702         if (rv < 0) {
703                 dev_err(dev, "usb_control_msg returned %d\n", rv);
704                 goto exit;
705         }
706         rv = 0;
707 
708 exit:
709         kfree(buffer);
710         return rv;
711 }
712 
713 static int usbtmc_ioctl_clear_out_halt(struct usbtmc_device_data *data)
714 {
715         u8 *buffer;
716         int rv;
717 
718         buffer = kmalloc(2, GFP_KERNEL);
719         if (!buffer)
720                 return -ENOMEM;
721 
722         rv = usb_control_msg(data->usb_dev,
723                              usb_sndctrlpipe(data->usb_dev, 0),
724                              USB_REQ_CLEAR_FEATURE,
725                              USB_DIR_OUT | USB_TYPE_STANDARD |
726                              USB_RECIP_ENDPOINT,
727                              USB_ENDPOINT_HALT, data->bulk_out,
728                              buffer, 0, USBTMC_TIMEOUT);
729 
730         if (rv < 0) {
731                 dev_err(&data->usb_dev->dev, "usb_control_msg returned %d\n",
732                         rv);
733                 goto exit;
734         }
735         rv = 0;
736 
737 exit:
738         kfree(buffer);
739         return rv;
740 }
741 
742 static int usbtmc_ioctl_clear_in_halt(struct usbtmc_device_data *data)
743 {
744         u8 *buffer;
745         int rv;
746 
747         buffer = kmalloc(2, GFP_KERNEL);
748         if (!buffer)
749                 return -ENOMEM;
750 
751         rv = usb_control_msg(data->usb_dev, usb_sndctrlpipe(data->usb_dev, 0),
752                              USB_REQ_CLEAR_FEATURE,
753                              USB_DIR_OUT | USB_TYPE_STANDARD |
754                              USB_RECIP_ENDPOINT,
755                              USB_ENDPOINT_HALT, data->bulk_in, buffer, 0,
756                              USBTMC_TIMEOUT);
757 
758         if (rv < 0) {
759                 dev_err(&data->usb_dev->dev, "usb_control_msg returned %d\n",
760                         rv);
761                 goto exit;
762         }
763         rv = 0;
764 
765 exit:
766         kfree(buffer);
767         return rv;
768 }
769 
770 static int get_capabilities(struct usbtmc_device_data *data)
771 {
772         struct device *dev = &data->usb_dev->dev;
773         char *buffer;
774         int rv = 0;
775 
776         buffer = kmalloc(0x18, GFP_KERNEL);
777         if (!buffer)
778                 return -ENOMEM;
779 
780         rv = usb_control_msg(data->usb_dev, usb_rcvctrlpipe(data->usb_dev, 0),
781                              USBTMC_REQUEST_GET_CAPABILITIES,
782                              USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
783                              0, 0, buffer, 0x18, USBTMC_TIMEOUT);
784         if (rv < 0) {
785                 dev_err(dev, "usb_control_msg returned %d\n", rv);
786                 goto err_out;
787         }
788 
789         dev_dbg(dev, "GET_CAPABILITIES returned %x\n", buffer[0]);
790         dev_dbg(dev, "Interface capabilities are %x\n", buffer[4]);
791         dev_dbg(dev, "Device capabilities are %x\n", buffer[5]);
792         dev_dbg(dev, "USB488 interface capabilities are %x\n", buffer[14]);
793         dev_dbg(dev, "USB488 device capabilities are %x\n", buffer[15]);
794         if (buffer[0] != USBTMC_STATUS_SUCCESS) {
795                 dev_err(dev, "GET_CAPABILITIES returned %x\n", buffer[0]);
796                 rv = -EPERM;
797                 goto err_out;
798         }
799 
800         data->capabilities.interface_capabilities = buffer[4];
801         data->capabilities.device_capabilities = buffer[5];
802         data->capabilities.usb488_interface_capabilities = buffer[14];
803         data->capabilities.usb488_device_capabilities = buffer[15];
804 
805 err_out:
806         kfree(buffer);
807         return rv;
808 }
809 
810 #define capability_attribute(name)                                      \
811 static ssize_t show_##name(struct device *dev,                          \
812                            struct device_attribute *attr, char *buf)    \
813 {                                                                       \
814         struct usb_interface *intf = to_usb_interface(dev);             \
815         struct usbtmc_device_data *data = usb_get_intfdata(intf);       \
816                                                                         \
817         return sprintf(buf, "%d\n", data->capabilities.name);           \
818 }                                                                       \
819 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
820 
821 capability_attribute(interface_capabilities);
822 capability_attribute(device_capabilities);
823 capability_attribute(usb488_interface_capabilities);
824 capability_attribute(usb488_device_capabilities);
825 
826 static struct attribute *capability_attrs[] = {
827         &dev_attr_interface_capabilities.attr,
828         &dev_attr_device_capabilities.attr,
829         &dev_attr_usb488_interface_capabilities.attr,
830         &dev_attr_usb488_device_capabilities.attr,
831         NULL,
832 };
833 
834 static struct attribute_group capability_attr_grp = {
835         .attrs = capability_attrs,
836 };
837 
838 static ssize_t show_TermChar(struct device *dev,
839                              struct device_attribute *attr, char *buf)
840 {
841         struct usb_interface *intf = to_usb_interface(dev);
842         struct usbtmc_device_data *data = usb_get_intfdata(intf);
843 
844         return sprintf(buf, "%c\n", data->TermChar);
845 }
846 
847 static ssize_t store_TermChar(struct device *dev,
848                               struct device_attribute *attr,
849                               const char *buf, size_t count)
850 {
851         struct usb_interface *intf = to_usb_interface(dev);
852         struct usbtmc_device_data *data = usb_get_intfdata(intf);
853 
854         if (count < 1)
855                 return -EINVAL;
856         data->TermChar = buf[0];
857         return count;
858 }
859 static DEVICE_ATTR(TermChar, S_IRUGO, show_TermChar, store_TermChar);
860 
861 #define data_attribute(name)                                            \
862 static ssize_t show_##name(struct device *dev,                          \
863                            struct device_attribute *attr, char *buf)    \
864 {                                                                       \
865         struct usb_interface *intf = to_usb_interface(dev);             \
866         struct usbtmc_device_data *data = usb_get_intfdata(intf);       \
867                                                                         \
868         return sprintf(buf, "%d\n", data->name);                        \
869 }                                                                       \
870 static ssize_t store_##name(struct device *dev,                         \
871                             struct device_attribute *attr,              \
872                             const char *buf, size_t count)              \
873 {                                                                       \
874         struct usb_interface *intf = to_usb_interface(dev);             \
875         struct usbtmc_device_data *data = usb_get_intfdata(intf);       \
876         ssize_t result;                                                 \
877         unsigned val;                                                   \
878                                                                         \
879         result = sscanf(buf, "%u\n", &val);                             \
880         if (result != 1)                                                \
881                 result = -EINVAL;                                       \
882         data->name = val;                                               \
883         if (result < 0)                                                 \
884                 return result;                                          \
885         else                                                            \
886                 return count;                                           \
887 }                                                                       \
888 static DEVICE_ATTR(name, S_IRUGO, show_##name, store_##name)
889 
890 data_attribute(TermCharEnabled);
891 data_attribute(auto_abort);
892 
893 static struct attribute *data_attrs[] = {
894         &dev_attr_TermChar.attr,
895         &dev_attr_TermCharEnabled.attr,
896         &dev_attr_auto_abort.attr,
897         NULL,
898 };
899 
900 static struct attribute_group data_attr_grp = {
901         .attrs = data_attrs,
902 };
903 
904 static int usbtmc_ioctl_indicator_pulse(struct usbtmc_device_data *data)
905 {
906         struct device *dev;
907         u8 *buffer;
908         int rv;
909 
910         dev = &data->intf->dev;
911 
912         buffer = kmalloc(2, GFP_KERNEL);
913         if (!buffer)
914                 return -ENOMEM;
915 
916         rv = usb_control_msg(data->usb_dev,
917                              usb_rcvctrlpipe(data->usb_dev, 0),
918                              USBTMC_REQUEST_INDICATOR_PULSE,
919                              USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
920                              0, 0, buffer, 0x01, USBTMC_TIMEOUT);
921 
922         if (rv < 0) {
923                 dev_err(dev, "usb_control_msg returned %d\n", rv);
924                 goto exit;
925         }
926 
927         dev_dbg(dev, "INDICATOR_PULSE returned %x\n", buffer[0]);
928 
929         if (buffer[0] != USBTMC_STATUS_SUCCESS) {
930                 dev_err(dev, "INDICATOR_PULSE returned %x\n", buffer[0]);
931                 rv = -EPERM;
932                 goto exit;
933         }
934         rv = 0;
935 
936 exit:
937         kfree(buffer);
938         return rv;
939 }
940 
941 static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
942 {
943         struct usbtmc_device_data *data;
944         int retval = -EBADRQC;
945 
946         data = file->private_data;
947         mutex_lock(&data->io_mutex);
948 
949         switch (cmd) {
950         case USBTMC_IOCTL_CLEAR_OUT_HALT:
951                 retval = usbtmc_ioctl_clear_out_halt(data);
952                 break;
953 
954         case USBTMC_IOCTL_CLEAR_IN_HALT:
955                 retval = usbtmc_ioctl_clear_in_halt(data);
956                 break;
957 
958         case USBTMC_IOCTL_INDICATOR_PULSE:
959                 retval = usbtmc_ioctl_indicator_pulse(data);
960                 break;
961 
962         case USBTMC_IOCTL_CLEAR:
963                 retval = usbtmc_ioctl_clear(data);
964                 break;
965 
966         case USBTMC_IOCTL_ABORT_BULK_OUT:
967                 retval = usbtmc_ioctl_abort_bulk_out(data);
968                 break;
969 
970         case USBTMC_IOCTL_ABORT_BULK_IN:
971                 retval = usbtmc_ioctl_abort_bulk_in(data);
972                 break;
973         }
974 
975         mutex_unlock(&data->io_mutex);
976         return retval;
977 }
978 
979 static struct file_operations fops = {
980         .owner          = THIS_MODULE,
981         .read           = usbtmc_read,
982         .write          = usbtmc_write,
983         .open           = usbtmc_open,
984         .release        = usbtmc_release,
985         .unlocked_ioctl = usbtmc_ioctl,
986 };
987 
988 static struct usb_class_driver usbtmc_class = {
989         .name =         "usbtmc%d",
990         .fops =         &fops,
991         .minor_base =   USBTMC_MINOR_BASE,
992 };
993 
994 
995 static int usbtmc_probe(struct usb_interface *intf,
996                         const struct usb_device_id *id)
997 {
998         struct usbtmc_device_data *data;
999         struct usb_host_interface *iface_desc;
1000         struct usb_endpoint_descriptor *endpoint;
1001         int n;
1002         int retcode;
1003 
1004         dev_dbg(&intf->dev, "%s called\n", __func__);
1005 
1006         data = kmalloc(sizeof(struct usbtmc_device_data), GFP_KERNEL);
1007         if (!data) {
1008                 dev_err(&intf->dev, "Unable to allocate kernel memory\n");
1009                 return -ENOMEM;
1010         }
1011 
1012         data->intf = intf;
1013         data->id = id;
1014         data->usb_dev = usb_get_dev(interface_to_usbdev(intf));
1015         usb_set_intfdata(intf, data);
1016         kref_init(&data->kref);
1017         mutex_init(&data->io_mutex);
1018 
1019         /* Initialize USBTMC bTag and other fields */
1020         data->bTag      = 1;
1021         data->TermCharEnabled = 0;
1022         data->TermChar = '\n';
1023 
1024         /* USBTMC devices have only one setting, so use that */
1025         iface_desc = data->intf->cur_altsetting;
1026 
1027         /* Find bulk in endpoint */
1028         for (n = 0; n < iface_desc->desc.bNumEndpoints; n++) {
1029                 endpoint = &iface_desc->endpoint[n].desc;
1030 
1031                 if (usb_endpoint_is_bulk_in(endpoint)) {
1032                         data->bulk_in = endpoint->bEndpointAddress;
1033                         dev_dbg(&intf->dev, "Found bulk in endpoint at %u\n",
1034                                 data->bulk_in);
1035                         break;
1036                 }
1037         }
1038 
1039         /* Find bulk out endpoint */
1040         for (n = 0; n < iface_desc->desc.bNumEndpoints; n++) {
1041                 endpoint = &iface_desc->endpoint[n].desc;
1042 
1043                 if (usb_endpoint_is_bulk_out(endpoint)) {
1044                         data->bulk_out = endpoint->bEndpointAddress;
1045                         dev_dbg(&intf->dev, "Found Bulk out endpoint at %u\n",
1046                                 data->bulk_out);
1047                         break;
1048                 }
1049         }
1050 
1051         retcode = get_capabilities(data);
1052         if (retcode)
1053                 dev_err(&intf->dev, "can't read capabilities\n");
1054         else
1055                 retcode = sysfs_create_group(&intf->dev.kobj,
1056                                              &capability_attr_grp);
1057 
1058         retcode = sysfs_create_group(&intf->dev.kobj, &data_attr_grp);
1059 
1060         retcode = usb_register_dev(intf, &usbtmc_class);
1061         if (retcode) {
1062                 dev_err(&intf->dev, "Not able to get a minor"
1063                         " (base %u, slice default): %d\n", USBTMC_MINOR_BASE,
1064                         retcode);
1065                 goto error_register;
1066         }
1067         dev_dbg(&intf->dev, "Using minor number %d\n", intf->minor);
1068 
1069         return 0;
1070 
1071 error_register:
1072         sysfs_remove_group(&intf->dev.kobj, &capability_attr_grp);
1073         sysfs_remove_group(&intf->dev.kobj, &data_attr_grp);
1074         kref_put(&data->kref, usbtmc_delete);
1075         return retcode;
1076 }
1077 
1078 static void usbtmc_disconnect(struct usb_interface *intf)
1079 {
1080         struct usbtmc_device_data *data;
1081 
1082         dev_dbg(&intf->dev, "usbtmc_disconnect called\n");
1083 
1084         data = usb_get_intfdata(intf);
1085         usb_deregister_dev(intf, &usbtmc_class);
1086         sysfs_remove_group(&intf->dev.kobj, &capability_attr_grp);
1087         sysfs_remove_group(&intf->dev.kobj, &data_attr_grp);
1088         kref_put(&data->kref, usbtmc_delete);
1089 }
1090 
1091 static struct usb_driver usbtmc_driver = {
1092         .name           = "usbtmc",
1093         .id_table       = usbtmc_devices,
1094         .probe          = usbtmc_probe,
1095         .disconnect     = usbtmc_disconnect
1096 };
1097 
1098 static int __init usbtmc_init(void)
1099 {
1100         int retcode;
1101 
1102         retcode = usb_register(&usbtmc_driver);
1103         if (retcode)
1104                 printk(KERN_ERR KBUILD_MODNAME": Unable to register driver\n");
1105         return retcode;
1106 }
1107 module_init(usbtmc_init);
1108 
1109 static void __exit usbtmc_exit(void)
1110 {
1111         usb_deregister(&usbtmc_driver);
1112 }
1113 module_exit(usbtmc_exit);
1114 
1115 MODULE_LICENSE("GPL");
1116 
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