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  * Linux driver for System z and s390 unit record devices
  3  * (z/VM virtual punch, reader, printer)
  4  *
  5  * Copyright IBM Corp. 2001, 2007
  6  * Authors: Malcolm Beattie <beattiem@uk.ibm.com>
  7  *          Michael Holzheu <holzheu@de.ibm.com>
  8  *          Frank Munzert <munzert@de.ibm.com>
  9  */
 10 
 11 #include <linux/cdev.h>
 12 
 13 #include <asm/uaccess.h>
 14 #include <asm/cio.h>
 15 #include <asm/ccwdev.h>
 16 #include <asm/debug.h>
 17 #include <asm/diag.h>
 18 
 19 #include "vmur.h"
 20 
 21 /*
 22  * Driver overview
 23  *
 24  * Unit record device support is implemented as a character device driver.
 25  * We can fit at least 16 bits into a device minor number and use the
 26  * simple method of mapping a character device number with minor abcd
 27  * to the unit record device with devno abcd.
 28  * I/O to virtual unit record devices is handled as follows:
 29  * Reads: Diagnose code 0x14 (input spool file manipulation)
 30  * is used to read spool data page-wise.
 31  * Writes: The CCW used is WRITE_CCW_CMD (0x01). The device's record length
 32  * is available by reading sysfs attr reclen. Each write() to the device
 33  * must specify an integral multiple (maximal 511) of reclen.
 34  */
 35 
 36 static char ur_banner[] = "z/VM virtual unit record device driver";
 37 
 38 MODULE_AUTHOR("IBM Corporation");
 39 MODULE_DESCRIPTION("s390 z/VM virtual unit record device driver");
 40 MODULE_LICENSE("GPL");
 41 
 42 #define PRINTK_HEADER "vmur: "
 43 
 44 static dev_t ur_first_dev_maj_min;
 45 static struct class *vmur_class;
 46 static struct debug_info *vmur_dbf;
 47 
 48 /* We put the device's record length (for writes) in the driver_info field */
 49 static struct ccw_device_id ur_ids[] = {
 50         { CCWDEV_CU_DI(READER_PUNCH_DEVTYPE, 80) },
 51         { CCWDEV_CU_DI(PRINTER_DEVTYPE, 132) },
 52         { /* end of list */ }
 53 };
 54 
 55 MODULE_DEVICE_TABLE(ccw, ur_ids);
 56 
 57 static int ur_probe(struct ccw_device *cdev);
 58 static void ur_remove(struct ccw_device *cdev);
 59 static int ur_set_online(struct ccw_device *cdev);
 60 static int ur_set_offline(struct ccw_device *cdev);
 61 
 62 static struct ccw_driver ur_driver = {
 63         .name           = "vmur",
 64         .owner          = THIS_MODULE,
 65         .ids            = ur_ids,
 66         .probe          = ur_probe,
 67         .remove         = ur_remove,
 68         .set_online     = ur_set_online,
 69         .set_offline    = ur_set_offline,
 70 };
 71 
 72 static DEFINE_MUTEX(vmur_mutex);
 73 
 74 /*
 75  * Allocation, freeing, getting and putting of urdev structures
 76  *
 77  * Each ur device (urd) contains a reference to its corresponding ccw device
 78  * (cdev) using the urd->cdev pointer. Each ccw device has a reference to the
 79  * ur device using the cdev->dev.driver_data pointer.
 80  *
 81  * urd references:
 82  * - ur_probe gets a urd reference, ur_remove drops the reference
 83  *   (cdev->dev.driver_data)
 84  * - ur_open gets a urd reference, ur_relase drops the reference
 85  *   (urf->urd)
 86  *
 87  * cdev references:
 88  * - urdev_alloc get a cdev reference (urd->cdev)
 89  * - urdev_free drops the cdev reference (urd->cdev)
 90  *
 91  * Setting and clearing of cdev->dev.driver_data is protected by the ccwdev lock
 92  */
 93 static struct urdev *urdev_alloc(struct ccw_device *cdev)
 94 {
 95         struct urdev *urd;
 96 
 97         urd = kzalloc(sizeof(struct urdev), GFP_KERNEL);
 98         if (!urd)
 99                 return NULL;
100         urd->reclen = cdev->id.driver_info;
101         ccw_device_get_id(cdev, &urd->dev_id);
102         mutex_init(&urd->io_mutex);
103         mutex_init(&urd->open_mutex);
104         atomic_set(&urd->ref_count,  1);
105         urd->cdev = cdev;
106         get_device(&cdev->dev);
107         return urd;
108 }
109 
110 static void urdev_free(struct urdev *urd)
111 {
112         TRACE("urdev_free: %p\n", urd);
113         if (urd->cdev)
114                 put_device(&urd->cdev->dev);
115         kfree(urd);
116 }
117 
118 static void urdev_get(struct urdev *urd)
119 {
120         atomic_inc(&urd->ref_count);
121 }
122 
123 static struct urdev *urdev_get_from_cdev(struct ccw_device *cdev)
124 {
125         struct urdev *urd;
126         unsigned long flags;
127 
128         spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
129         urd = cdev->dev.driver_data;
130         if (urd)
131                 urdev_get(urd);
132         spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
133         return urd;
134 }
135 
136 static struct urdev *urdev_get_from_devno(u16 devno)
137 {
138         char bus_id[16];
139         struct ccw_device *cdev;
140         struct urdev *urd;
141 
142         sprintf(bus_id, "0.0.%04x", devno);
143         cdev = get_ccwdev_by_busid(&ur_driver, bus_id);
144         if (!cdev)
145                 return NULL;
146         urd = urdev_get_from_cdev(cdev);
147         put_device(&cdev->dev);
148         return urd;
149 }
150 
151 static void urdev_put(struct urdev *urd)
152 {
153         if (atomic_dec_and_test(&urd->ref_count))
154                 urdev_free(urd);
155 }
156 
157 /*
158  * Low-level functions to do I/O to a ur device.
159  *     alloc_chan_prog
160  *     free_chan_prog
161  *     do_ur_io
162  *     ur_int_handler
163  *
164  * alloc_chan_prog allocates and builds the channel program
165  * free_chan_prog frees memory of the channel program
166  *
167  * do_ur_io issues the channel program to the device and blocks waiting
168  * on a completion event it publishes at urd->io_done. The function
169  * serialises itself on the device's mutex so that only one I/O
170  * is issued at a time (and that I/O is synchronous).
171  *
172  * ur_int_handler catches the "I/O done" interrupt, writes the
173  * subchannel status word into the scsw member of the urdev structure
174  * and complete()s the io_done to wake the waiting do_ur_io.
175  *
176  * The caller of do_ur_io is responsible for kfree()ing the channel program
177  * address pointer that alloc_chan_prog returned.
178  */
179 
180 static void free_chan_prog(struct ccw1 *cpa)
181 {
182         struct ccw1 *ptr = cpa;
183 
184         while (ptr->cda) {
185                 kfree((void *)(addr_t) ptr->cda);
186                 ptr++;
187         }
188         kfree(cpa);
189 }
190 
191 /*
192  * alloc_chan_prog
193  * The channel program we use is write commands chained together
194  * with a final NOP CCW command-chained on (which ensures that CE and DE
195  * are presented together in a single interrupt instead of as separate
196  * interrupts unless an incorrect length indication kicks in first). The
197  * data length in each CCW is reclen.
198  */
199 static struct ccw1 *alloc_chan_prog(const char __user *ubuf, int rec_count,
200                                     int reclen)
201 {
202         struct ccw1 *cpa;
203         void *kbuf;
204         int i;
205 
206         TRACE("alloc_chan_prog(%p, %i, %i)\n", ubuf, rec_count, reclen);
207 
208         /*
209          * We chain a NOP onto the writes to force CE+DE together.
210          * That means we allocate room for CCWs to cover count/reclen
211          * records plus a NOP.
212          */
213         cpa = kzalloc((rec_count + 1) * sizeof(struct ccw1),
214                       GFP_KERNEL | GFP_DMA);
215         if (!cpa)
216                 return ERR_PTR(-ENOMEM);
217 
218         for (i = 0; i < rec_count; i++) {
219                 cpa[i].cmd_code = WRITE_CCW_CMD;
220                 cpa[i].flags = CCW_FLAG_CC | CCW_FLAG_SLI;
221                 cpa[i].count = reclen;
222                 kbuf = kmalloc(reclen, GFP_KERNEL | GFP_DMA);
223                 if (!kbuf) {
224                         free_chan_prog(cpa);
225                         return ERR_PTR(-ENOMEM);
226                 }
227                 cpa[i].cda = (u32)(addr_t) kbuf;
228                 if (copy_from_user(kbuf, ubuf, reclen)) {
229                         free_chan_prog(cpa);
230                         return ERR_PTR(-EFAULT);
231                 }
232                 ubuf += reclen;
233         }
234         /* The following NOP CCW forces CE+DE to be presented together */
235         cpa[i].cmd_code = CCW_CMD_NOOP;
236         return cpa;
237 }
238 
239 static int do_ur_io(struct urdev *urd, struct ccw1 *cpa)
240 {
241         int rc;
242         struct ccw_device *cdev = urd->cdev;
243         DECLARE_COMPLETION_ONSTACK(event);
244 
245         TRACE("do_ur_io: cpa=%p\n", cpa);
246 
247         rc = mutex_lock_interruptible(&urd->io_mutex);
248         if (rc)
249                 return rc;
250 
251         urd->io_done = &event;
252 
253         spin_lock_irq(get_ccwdev_lock(cdev));
254         rc = ccw_device_start(cdev, cpa, 1, 0, 0);
255         spin_unlock_irq(get_ccwdev_lock(cdev));
256 
257         TRACE("do_ur_io: ccw_device_start returned %d\n", rc);
258         if (rc)
259                 goto out;
260 
261         wait_for_completion(&event);
262         TRACE("do_ur_io: I/O complete\n");
263         rc = 0;
264 
265 out:
266         mutex_unlock(&urd->io_mutex);
267         return rc;
268 }
269 
270 /*
271  * ur interrupt handler, called from the ccw_device layer
272  */
273 static void ur_int_handler(struct ccw_device *cdev, unsigned long intparm,
274                            struct irb *irb)
275 {
276         struct urdev *urd;
277 
278         TRACE("ur_int_handler: intparm=0x%lx cstat=%02x dstat=%02x res=%u\n",
279               intparm, irb->scsw.cstat, irb->scsw.dstat, irb->scsw.count);
280 
281         if (!intparm) {
282                 TRACE("ur_int_handler: unsolicited interrupt\n");
283                 return;
284         }
285         urd = cdev->dev.driver_data;
286         BUG_ON(!urd);
287         /* On special conditions irb is an error pointer */
288         if (IS_ERR(irb))
289                 urd->io_request_rc = PTR_ERR(irb);
290         else if (irb->scsw.dstat == (DEV_STAT_CHN_END | DEV_STAT_DEV_END))
291                 urd->io_request_rc = 0;
292         else
293                 urd->io_request_rc = -EIO;
294 
295         complete(urd->io_done);
296 }
297 
298 /*
299  * reclen sysfs attribute - The record length to be used for write CCWs
300  */
301 static ssize_t ur_attr_reclen_show(struct device *dev,
302                                    struct device_attribute *attr, char *buf)
303 {
304         struct urdev *urd;
305         int rc;
306 
307         urd = urdev_get_from_cdev(to_ccwdev(dev));
308         if (!urd)
309                 return -ENODEV;
310         rc = sprintf(buf, "%zu\n", urd->reclen);
311         urdev_put(urd);
312         return rc;
313 }
314 
315 static DEVICE_ATTR(reclen, 0444, ur_attr_reclen_show, NULL);
316 
317 static int ur_create_attributes(struct device *dev)
318 {
319         return device_create_file(dev, &dev_attr_reclen);
320 }
321 
322 static void ur_remove_attributes(struct device *dev)
323 {
324         device_remove_file(dev, &dev_attr_reclen);
325 }
326 
327 /*
328  * diagnose code 0x210 - retrieve device information
329  * cc=0  normal completion, we have a real device
330  * cc=1  CP paging error
331  * cc=2  The virtual device exists, but is not associated with a real device
332  * cc=3  Invalid device address, or the virtual device does not exist
333  */
334 static int get_urd_class(struct urdev *urd)
335 {
336         static struct diag210 ur_diag210;
337         int cc;
338 
339         ur_diag210.vrdcdvno = urd->dev_id.devno;
340         ur_diag210.vrdclen = sizeof(struct diag210);
341 
342         cc = diag210(&ur_diag210);
343         switch (cc) {
344         case 0:
345                 return -ENOTSUPP;
346         case 2:
347                 return ur_diag210.vrdcvcla; /* virtual device class */
348         case 3:
349                 return -ENODEV;
350         default:
351                 return -EIO;
352         }
353 }
354 
355 /*
356  * Allocation and freeing of urfile structures
357  */
358 static struct urfile *urfile_alloc(struct urdev *urd)
359 {
360         struct urfile *urf;
361 
362         urf = kzalloc(sizeof(struct urfile), GFP_KERNEL);
363         if (!urf)
364                 return NULL;
365         urf->urd = urd;
366 
367         TRACE("urfile_alloc: urd=%p urf=%p rl=%zu\n", urd, urf,
368               urf->dev_reclen);
369 
370         return urf;
371 }
372 
373 static void urfile_free(struct urfile *urf)
374 {
375         TRACE("urfile_free: urf=%p urd=%p\n", urf, urf->urd);
376         kfree(urf);
377 }
378 
379 /*
380  * The fops implementation of the character device driver
381  */
382 static ssize_t do_write(struct urdev *urd, const char __user *udata,
383                         size_t count, size_t reclen, loff_t *ppos)
384 {
385         struct ccw1 *cpa;
386         int rc;
387 
388         cpa = alloc_chan_prog(udata, count / reclen, reclen);
389         if (IS_ERR(cpa))
390                 return PTR_ERR(cpa);
391 
392         rc = do_ur_io(urd, cpa);
393         if (rc)
394                 goto fail_kfree_cpa;
395 
396         if (urd->io_request_rc) {
397                 rc = urd->io_request_rc;
398                 goto fail_kfree_cpa;
399         }
400         *ppos += count;
401         rc = count;
402 
403 fail_kfree_cpa:
404         free_chan_prog(cpa);
405         return rc;
406 }
407 
408 static ssize_t ur_write(struct file *file, const char __user *udata,
409                         size_t count, loff_t *ppos)
410 {
411         struct urfile *urf = file->private_data;
412 
413         TRACE("ur_write: count=%zu\n", count);
414 
415         if (count == 0)
416                 return 0;
417 
418         if (count % urf->dev_reclen)
419                 return -EINVAL; /* count must be a multiple of reclen */
420 
421         if (count > urf->dev_reclen * MAX_RECS_PER_IO)
422                 count = urf->dev_reclen * MAX_RECS_PER_IO;
423 
424         return do_write(urf->urd, udata, count, urf->dev_reclen, ppos);
425 }
426 
427 /*
428  * diagnose code 0x14 subcode 0x0028 - position spool file to designated
429  *                                     record
430  * cc=0  normal completion
431  * cc=2  no file active on the virtual reader or device not ready
432  * cc=3  record specified is beyond EOF
433  */
434 static int diag_position_to_record(int devno, int record)
435 {
436         int cc;
437 
438         cc = diag14(record, devno, 0x28);
439         switch (cc) {
440         case 0:
441                 return 0;
442         case 2:
443                 return -ENOMEDIUM;
444         case 3:
445                 return -ENODATA; /* position beyond end of file */
446         default:
447                 return -EIO;
448         }
449 }
450 
451 /*
452  * diagnose code 0x14 subcode 0x0000 - read next spool file buffer
453  * cc=0  normal completion
454  * cc=1  EOF reached
455  * cc=2  no file active on the virtual reader, and no file eligible
456  * cc=3  file already active on the virtual reader or specified virtual
457  *       reader does not exist or is not a reader
458  */
459 static int diag_read_file(int devno, char *buf)
460 {
461         int cc;
462 
463         cc = diag14((unsigned long) buf, devno, 0x00);
464         switch (cc) {
465         case 0:
466                 return 0;
467         case 1:
468                 return -ENODATA;
469         case 2:
470                 return -ENOMEDIUM;
471         default:
472                 return -EIO;
473         }
474 }
475 
476 static ssize_t diag14_read(struct file *file, char __user *ubuf, size_t count,
477                            loff_t *offs)
478 {
479         size_t len, copied, res;
480         char *buf;
481         int rc;
482         u16 reclen;
483         struct urdev *urd;
484 
485         urd = ((struct urfile *) file->private_data)->urd;
486         reclen = ((struct urfile *) file->private_data)->file_reclen;
487 
488         rc = diag_position_to_record(urd->dev_id.devno, *offs / PAGE_SIZE + 1);
489         if (rc == -ENODATA)
490                 return 0;
491         if (rc)
492                 return rc;
493 
494         len = min((size_t) PAGE_SIZE, count);
495         buf = (char *) __get_free_page(GFP_KERNEL | GFP_DMA);
496         if (!buf)
497                 return -ENOMEM;
498 
499         copied = 0;
500         res = (size_t) (*offs % PAGE_SIZE);
501         do {
502                 rc = diag_read_file(urd->dev_id.devno, buf);
503                 if (rc == -ENODATA) {
504                         break;
505                 }
506                 if (rc)
507                         goto fail;
508                 if (reclen && (copied == 0) && (*offs < PAGE_SIZE))
509                         *((u16 *) &buf[FILE_RECLEN_OFFSET]) = reclen;
510                 len = min(count - copied, PAGE_SIZE - res);
511                 if (copy_to_user(ubuf + copied, buf + res, len)) {
512                         rc = -EFAULT;
513                         goto fail;
514                 }
515                 res = 0;
516                 copied += len;
517         } while (copied != count);
518 
519         *offs += copied;
520         rc = copied;
521 fail:
522         free_page((unsigned long) buf);
523         return rc;
524 }
525 
526 static ssize_t ur_read(struct file *file, char __user *ubuf, size_t count,
527                        loff_t *offs)
528 {
529         struct urdev *urd;
530         int rc;
531 
532         TRACE("ur_read: count=%zu ppos=%li\n", count, (unsigned long) *offs);
533 
534         if (count == 0)
535                 return 0;
536 
537         urd = ((struct urfile *) file->private_data)->urd;
538         rc = mutex_lock_interruptible(&urd->io_mutex);
539         if (rc)
540                 return rc;
541         rc = diag14_read(file, ubuf, count, offs);
542         mutex_unlock(&urd->io_mutex);
543         return rc;
544 }
545 
546 /*
547  * diagnose code 0x14 subcode 0x0fff - retrieve next file descriptor
548  * cc=0  normal completion
549  * cc=1  no files on reader queue or no subsequent file
550  * cc=2  spid specified is invalid
551  */
552 static int diag_read_next_file_info(struct file_control_block *buf, int spid)
553 {
554         int cc;
555 
556         cc = diag14((unsigned long) buf, spid, 0xfff);
557         switch (cc) {
558         case 0:
559                 return 0;
560         default:
561                 return -ENODATA;
562         }
563 }
564 
565 static int verify_uri_device(struct urdev *urd)
566 {
567         struct file_control_block *fcb;
568         char *buf;
569         int rc;
570 
571         fcb = kmalloc(sizeof(*fcb), GFP_KERNEL | GFP_DMA);
572         if (!fcb)
573                 return -ENOMEM;
574 
575         /* check for empty reader device (beginning of chain) */
576         rc = diag_read_next_file_info(fcb, 0);
577         if (rc)
578                 goto fail_free_fcb;
579 
580         /* if file is in hold status, we do not read it */
581         if (fcb->file_stat & (FLG_SYSTEM_HOLD | FLG_USER_HOLD)) {
582                 rc = -EPERM;
583                 goto fail_free_fcb;
584         }
585 
586         /* open file on virtual reader  */
587         buf = (char *) __get_free_page(GFP_KERNEL | GFP_DMA);
588         if (!buf) {
589                 rc = -ENOMEM;
590                 goto fail_free_fcb;
591         }
592         rc = diag_read_file(urd->dev_id.devno, buf);
593         if ((rc != 0) && (rc != -ENODATA)) /* EOF does not hurt */
594                 goto fail_free_buf;
595 
596         /* check if the file on top of the queue is open now */
597         rc = diag_read_next_file_info(fcb, 0);
598         if (rc)
599                 goto fail_free_buf;
600         if (!(fcb->file_stat & FLG_IN_USE)) {
601                 rc = -EMFILE;
602                 goto fail_free_buf;
603         }
604         rc = 0;
605 
606 fail_free_buf:
607         free_page((unsigned long) buf);
608 fail_free_fcb:
609         kfree(fcb);
610         return rc;
611 }
612 
613 static int verify_device(struct urdev *urd)
614 {
615         switch (urd->class) {
616         case DEV_CLASS_UR_O:
617                 return 0; /* no check needed here */
618         case DEV_CLASS_UR_I:
619                 return verify_uri_device(urd);
620         default:
621                 return -ENOTSUPP;
622         }
623 }
624 
625 static int get_uri_file_reclen(struct urdev *urd)
626 {
627         struct file_control_block *fcb;
628         int rc;
629 
630         fcb = kmalloc(sizeof(*fcb), GFP_KERNEL | GFP_DMA);
631         if (!fcb)
632                 return -ENOMEM;
633         rc = diag_read_next_file_info(fcb, 0);
634         if (rc)
635                 goto fail_free;
636         if (fcb->file_stat & FLG_CP_DUMP)
637                 rc = 0;
638         else
639                 rc = fcb->rec_len;
640 
641 fail_free:
642         kfree(fcb);
643         return rc;
644 }
645 
646 static int get_file_reclen(struct urdev *urd)
647 {
648         switch (urd->class) {
649         case DEV_CLASS_UR_O:
650                 return 0;
651         case DEV_CLASS_UR_I:
652                 return get_uri_file_reclen(urd);
653         default:
654                 return -ENOTSUPP;
655         }
656 }
657 
658 static int ur_open(struct inode *inode, struct file *file)
659 {
660         u16 devno;
661         struct urdev *urd;
662         struct urfile *urf;
663         unsigned short accmode;
664         int rc;
665 
666         accmode = file->f_flags & O_ACCMODE;
667 
668         if (accmode == O_RDWR)
669                 return -EACCES;
670 
671         /*
672          * We treat the minor number as the devno of the ur device
673          * to find in the driver tree.
674          */
675         devno = MINOR(file->f_dentry->d_inode->i_rdev);
676 
677         urd = urdev_get_from_devno(devno);
678         if (!urd)
679                 return -ENXIO;
680 
681         if (file->f_flags & O_NONBLOCK) {
682                 if (!mutex_trylock(&urd->open_mutex)) {
683                         rc = -EBUSY;
684                         goto fail_put;
685                 }
686         } else {
687                 if (mutex_lock_interruptible(&urd->open_mutex)) {
688                         rc = -ERESTARTSYS;
689                         goto fail_put;
690                 }
691         }
692 
693         TRACE("ur_open\n");
694 
695         if (((accmode == O_RDONLY) && (urd->class != DEV_CLASS_UR_I)) ||
696             ((accmode == O_WRONLY) && (urd->class != DEV_CLASS_UR_O))) {
697                 TRACE("ur_open: unsupported dev class (%d)\n", urd->class);
698                 rc = -EACCES;
699                 goto fail_unlock;
700         }
701 
702         rc = verify_device(urd);
703         if (rc)
704                 goto fail_unlock;
705 
706         urf = urfile_alloc(urd);
707         if (!urf) {
708                 rc = -ENOMEM;
709                 goto fail_unlock;
710         }
711 
712         urf->dev_reclen = urd->reclen;
713         rc = get_file_reclen(urd);
714         if (rc < 0)
715                 goto fail_urfile_free;
716         urf->file_reclen = rc;
717         file->private_data = urf;
718         return 0;
719 
720 fail_urfile_free:
721         urfile_free(urf);
722 fail_unlock:
723         mutex_unlock(&urd->open_mutex);
724 fail_put:
725         urdev_put(urd);
726         return rc;
727 }
728 
729 static int ur_release(struct inode *inode, struct file *file)
730 {
731         struct urfile *urf = file->private_data;
732 
733         TRACE("ur_release\n");
734         mutex_unlock(&urf->urd->open_mutex);
735         urdev_put(urf->urd);
736         urfile_free(urf);
737         return 0;
738 }
739 
740 static loff_t ur_llseek(struct file *file, loff_t offset, int whence)
741 {
742         loff_t newpos;
743 
744         if ((file->f_flags & O_ACCMODE) != O_RDONLY)
745                 return -ESPIPE; /* seek allowed only for reader */
746         if (offset % PAGE_SIZE)
747                 return -ESPIPE; /* only multiples of 4K allowed */
748         switch (whence) {
749         case 0: /* SEEK_SET */
750                 newpos = offset;
751                 break;
752         case 1: /* SEEK_CUR */
753                 newpos = file->f_pos + offset;
754                 break;
755         default:
756                 return -EINVAL;
757         }
758         file->f_pos = newpos;
759         return newpos;
760 }
761 
762 static const struct file_operations ur_fops = {
763         .owner   = THIS_MODULE,
764         .open    = ur_open,
765         .release = ur_release,
766         .read    = ur_read,
767         .write   = ur_write,
768         .llseek  = ur_llseek,
769 };
770 
771 /*
772  * ccw_device infrastructure:
773  *     ur_probe creates the struct urdev (with refcount = 1), the device
774  *     attributes, sets up the interrupt handler and validates the virtual
775  *     unit record device.
776  *     ur_remove removes the device attributes and drops the reference to
777  *     struct urdev.
778  *
779  *     ur_probe, ur_remove, ur_set_online and ur_set_offline are serialized
780  *     by the vmur_mutex lock.
781  *
782  *     urd->char_device is used as indication that the online function has
783  *     been completed successfully.
784  */
785 static int ur_probe(struct ccw_device *cdev)
786 {
787         struct urdev *urd;
788         int rc;
789 
790         TRACE("ur_probe: cdev=%p\n", cdev);
791 
792         mutex_lock(&vmur_mutex);
793         urd = urdev_alloc(cdev);
794         if (!urd) {
795                 rc = -ENOMEM;
796                 goto fail_unlock;
797         }
798 
799         rc = ur_create_attributes(&cdev->dev);
800         if (rc) {
801                 rc = -ENOMEM;
802                 goto fail_urdev_put;
803         }
804         cdev->handler = ur_int_handler;
805 
806         /* validate virtual unit record device */
807         urd->class = get_urd_class(urd);
808         if (urd->class < 0) {
809                 rc = urd->class;
810                 goto fail_remove_attr;
811         }
812         if ((urd->class != DEV_CLASS_UR_I) && (urd->class != DEV_CLASS_UR_O)) {
813                 rc = -ENOTSUPP;
814                 goto fail_remove_attr;
815         }
816         spin_lock_irq(get_ccwdev_lock(cdev));
817         cdev->dev.driver_data = urd;
818         spin_unlock_irq(get_ccwdev_lock(cdev));
819 
820         mutex_unlock(&vmur_mutex);
821         return 0;
822 
823 fail_remove_attr:
824         ur_remove_attributes(&cdev->dev);
825 fail_urdev_put:
826         urdev_put(urd);
827 fail_unlock:
828         mutex_unlock(&vmur_mutex);
829         return rc;
830 }
831 
832 static int ur_set_online(struct ccw_device *cdev)
833 {
834         struct urdev *urd;
835         int minor, major, rc;
836         char node_id[16];
837 
838         TRACE("ur_set_online: cdev=%p\n", cdev);
839 
840         mutex_lock(&vmur_mutex);
841         urd = urdev_get_from_cdev(cdev);
842         if (!urd) {
843                 /* ur_remove already deleted our urd */
844                 rc = -ENODEV;
845                 goto fail_unlock;
846         }
847 
848         if (urd->char_device) {
849                 /* Another ur_set_online was faster */
850                 rc = -EBUSY;
851                 goto fail_urdev_put;
852         }
853 
854         minor = urd->dev_id.devno;
855         major = MAJOR(ur_first_dev_maj_min);
856 
857         urd->char_device = cdev_alloc();
858         if (!urd->char_device) {
859                 rc = -ENOMEM;
860                 goto fail_urdev_put;
861         }
862 
863         cdev_init(urd->char_device, &ur_fops);
864         urd->char_device->dev = MKDEV(major, minor);
865         urd->char_device->owner = ur_fops.owner;
866 
867         rc = cdev_add(urd->char_device, urd->char_device->dev, 1);
868         if (rc)
869                 goto fail_free_cdev;
870         if (urd->cdev->id.cu_type == READER_PUNCH_DEVTYPE) {
871                 if (urd->class == DEV_CLASS_UR_I)
872                         sprintf(node_id, "vmrdr-%s", cdev->dev.bus_id);
873                 if (urd->class == DEV_CLASS_UR_O)
874                         sprintf(node_id, "vmpun-%s", cdev->dev.bus_id);
875         } else if (urd->cdev->id.cu_type == PRINTER_DEVTYPE) {
876                 sprintf(node_id, "vmprt-%s", cdev->dev.bus_id);
877         } else {
878                 rc = -ENOTSUPP;
879                 goto fail_free_cdev;
880         }
881 
882         urd->device = device_create(vmur_class, NULL, urd->char_device->dev,
883                                         "%s", node_id);
884         if (IS_ERR(urd->device)) {
885                 rc = PTR_ERR(urd->device);
886                 TRACE("ur_set_online: device_create rc=%d\n", rc);
887                 goto fail_free_cdev;
888         }
889         urdev_put(urd);
890         mutex_unlock(&vmur_mutex);
891         return 0;
892 
893 fail_free_cdev:
894         cdev_del(urd->char_device);
895         urd->char_device = NULL;
896 fail_urdev_put:
897         urdev_put(urd);
898 fail_unlock:
899         mutex_unlock(&vmur_mutex);
900         return rc;
901 }
902 
903 static int ur_set_offline_force(struct ccw_device *cdev, int force)
904 {
905         struct urdev *urd;
906         int rc;
907 
908         TRACE("ur_set_offline: cdev=%p\n", cdev);
909         urd = urdev_get_from_cdev(cdev);
910         if (!urd)
911                 /* ur_remove already deleted our urd */
912                 return -ENODEV;
913         if (!urd->char_device) {
914                 /* Another ur_set_offline was faster */
915                 rc = -EBUSY;
916                 goto fail_urdev_put;
917         }
918         if (!force && (atomic_read(&urd->ref_count) > 2)) {
919                 /* There is still a user of urd (e.g. ur_open) */
920                 TRACE("ur_set_offline: BUSY\n");
921                 rc = -EBUSY;
922                 goto fail_urdev_put;
923         }
924         device_destroy(vmur_class, urd->char_device->dev);
925         cdev_del(urd->char_device);
926         urd->char_device = NULL;
927         rc = 0;
928 
929 fail_urdev_put:
930         urdev_put(urd);
931         return rc;
932 }
933 
934 static int ur_set_offline(struct ccw_device *cdev)
935 {
936         int rc;
937 
938         mutex_lock(&vmur_mutex);
939         rc = ur_set_offline_force(cdev, 0);
940         mutex_unlock(&vmur_mutex);
941         return rc;
942 }
943 
944 static void ur_remove(struct ccw_device *cdev)
945 {
946         unsigned long flags;
947 
948         TRACE("ur_remove\n");
949 
950         mutex_lock(&vmur_mutex);
951 
952         if (cdev->online)
953                 ur_set_offline_force(cdev, 1);
954         ur_remove_attributes(&cdev->dev);
955 
956         spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
957         urdev_put(cdev->dev.driver_data);
958         cdev->dev.driver_data = NULL;
959         spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
960 
961         mutex_unlock(&vmur_mutex);
962 }
963 
964 /*
965  * Module initialisation and cleanup
966  */
967 static int __init ur_init(void)
968 {
969         int rc;
970         dev_t dev;
971 
972         if (!MACHINE_IS_VM) {
973                 PRINT_ERR("%s is only available under z/VM.\n", ur_banner);
974                 return -ENODEV;
975         }
976 
977         vmur_dbf = debug_register("vmur", 4, 1, 4 * sizeof(long));
978         if (!vmur_dbf)
979                 return -ENOMEM;
980         rc = debug_register_view(vmur_dbf, &debug_sprintf_view);
981         if (rc)
982                 goto fail_free_dbf;
983 
984         debug_set_level(vmur_dbf, 6);
985 
986         rc = ccw_driver_register(&ur_driver);
987         if (rc)
988                 goto fail_free_dbf;
989 
990         rc = alloc_chrdev_region(&dev, 0, NUM_MINORS, "vmur");
991         if (rc) {
992                 PRINT_ERR("alloc_chrdev_region failed: err = %d\n", rc);
993                 goto fail_unregister_driver;
994         }
995         ur_first_dev_maj_min = MKDEV(MAJOR(dev), 0);
996 
997         vmur_class = class_create(THIS_MODULE, "vmur");
998         if (IS_ERR(vmur_class)) {
999                 rc = PTR_ERR(vmur_class);
1000                 goto fail_unregister_region;
1001         }
1002         PRINT_INFO("%s loaded.\n", ur_banner);
1003         return 0;
1004 
1005 fail_unregister_region:
1006         unregister_chrdev_region(ur_first_dev_maj_min, NUM_MINORS);
1007 fail_unregister_driver:
1008         ccw_driver_unregister(&ur_driver);
1009 fail_free_dbf:
1010         debug_unregister(vmur_dbf);
1011         return rc;
1012 }
1013 
1014 static void __exit ur_exit(void)
1015 {
1016         class_destroy(vmur_class);
1017         unregister_chrdev_region(ur_first_dev_maj_min, NUM_MINORS);
1018         ccw_driver_unregister(&ur_driver);
1019         debug_unregister(vmur_dbf);
1020         PRINT_INFO("%s unloaded.\n", ur_banner);
1021 }
1022 
1023 module_init(ur_init);
1024 module_exit(ur_exit);
1025 
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