xref: /openbmc/linux/drivers/s390/block/dcssblk.c (revision 92a2c6b2)
1 /*
2  * dcssblk.c -- the S/390 block driver for dcss memory
3  *
4  * Authors: Carsten Otte, Stefan Weinhuber, Gerald Schaefer
5  */
6 
7 #define KMSG_COMPONENT "dcssblk"
8 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
9 
10 #include <linux/module.h>
11 #include <linux/moduleparam.h>
12 #include <linux/ctype.h>
13 #include <linux/errno.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/blkdev.h>
17 #include <linux/completion.h>
18 #include <linux/interrupt.h>
19 #include <linux/platform_device.h>
20 #include <asm/extmem.h>
21 #include <asm/io.h>
22 
23 #define DCSSBLK_NAME "dcssblk"
24 #define DCSSBLK_MINORS_PER_DISK 1
25 #define DCSSBLK_PARM_LEN 400
26 #define DCSS_BUS_ID_SIZE 20
27 
28 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
29 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
30 static void dcssblk_make_request(struct request_queue *q, struct bio *bio);
31 static long dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
32 				 void **kaddr, unsigned long *pfn, long size);
33 
34 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
35 
36 static int dcssblk_major;
37 static const struct block_device_operations dcssblk_devops = {
38 	.owner   	= THIS_MODULE,
39 	.open    	= dcssblk_open,
40 	.release 	= dcssblk_release,
41 	.direct_access 	= dcssblk_direct_access,
42 };
43 
44 struct dcssblk_dev_info {
45 	struct list_head lh;
46 	struct device dev;
47 	char segment_name[DCSS_BUS_ID_SIZE];
48 	atomic_t use_count;
49 	struct gendisk *gd;
50 	unsigned long start;
51 	unsigned long end;
52 	int segment_type;
53 	unsigned char save_pending;
54 	unsigned char is_shared;
55 	struct request_queue *dcssblk_queue;
56 	int num_of_segments;
57 	struct list_head seg_list;
58 };
59 
60 struct segment_info {
61 	struct list_head lh;
62 	char segment_name[DCSS_BUS_ID_SIZE];
63 	unsigned long start;
64 	unsigned long end;
65 	int segment_type;
66 };
67 
68 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
69 				  size_t count);
70 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
71 				  size_t count);
72 
73 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
74 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
75 
76 static struct device *dcssblk_root_dev;
77 
78 static LIST_HEAD(dcssblk_devices);
79 static struct rw_semaphore dcssblk_devices_sem;
80 
81 /*
82  * release function for segment device.
83  */
84 static void
85 dcssblk_release_segment(struct device *dev)
86 {
87 	struct dcssblk_dev_info *dev_info;
88 	struct segment_info *entry, *temp;
89 
90 	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
91 	list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
92 		list_del(&entry->lh);
93 		kfree(entry);
94 	}
95 	kfree(dev_info);
96 	module_put(THIS_MODULE);
97 }
98 
99 /*
100  * get a minor number. needs to be called with
101  * down_write(&dcssblk_devices_sem) and the
102  * device needs to be enqueued before the semaphore is
103  * freed.
104  */
105 static int
106 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
107 {
108 	int minor, found;
109 	struct dcssblk_dev_info *entry;
110 
111 	if (dev_info == NULL)
112 		return -EINVAL;
113 	for (minor = 0; minor < (1<<MINORBITS); minor++) {
114 		found = 0;
115 		// test if minor available
116 		list_for_each_entry(entry, &dcssblk_devices, lh)
117 			if (minor == entry->gd->first_minor)
118 				found++;
119 		if (!found) break; // got unused minor
120 	}
121 	if (found)
122 		return -EBUSY;
123 	dev_info->gd->first_minor = minor;
124 	return 0;
125 }
126 
127 /*
128  * get the struct dcssblk_dev_info from dcssblk_devices
129  * for the given name.
130  * down_read(&dcssblk_devices_sem) must be held.
131  */
132 static struct dcssblk_dev_info *
133 dcssblk_get_device_by_name(char *name)
134 {
135 	struct dcssblk_dev_info *entry;
136 
137 	list_for_each_entry(entry, &dcssblk_devices, lh) {
138 		if (!strcmp(name, entry->segment_name)) {
139 			return entry;
140 		}
141 	}
142 	return NULL;
143 }
144 
145 /*
146  * get the struct segment_info from seg_list
147  * for the given name.
148  * down_read(&dcssblk_devices_sem) must be held.
149  */
150 static struct segment_info *
151 dcssblk_get_segment_by_name(char *name)
152 {
153 	struct dcssblk_dev_info *dev_info;
154 	struct segment_info *entry;
155 
156 	list_for_each_entry(dev_info, &dcssblk_devices, lh) {
157 		list_for_each_entry(entry, &dev_info->seg_list, lh) {
158 			if (!strcmp(name, entry->segment_name))
159 				return entry;
160 		}
161 	}
162 	return NULL;
163 }
164 
165 /*
166  * get the highest address of the multi-segment block.
167  */
168 static unsigned long
169 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
170 {
171 	unsigned long highest_addr;
172 	struct segment_info *entry;
173 
174 	highest_addr = 0;
175 	list_for_each_entry(entry, &dev_info->seg_list, lh) {
176 		if (highest_addr < entry->end)
177 			highest_addr = entry->end;
178 	}
179 	return highest_addr;
180 }
181 
182 /*
183  * get the lowest address of the multi-segment block.
184  */
185 static unsigned long
186 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
187 {
188 	int set_first;
189 	unsigned long lowest_addr;
190 	struct segment_info *entry;
191 
192 	set_first = 0;
193 	lowest_addr = 0;
194 	list_for_each_entry(entry, &dev_info->seg_list, lh) {
195 		if (set_first == 0) {
196 			lowest_addr = entry->start;
197 			set_first = 1;
198 		} else {
199 			if (lowest_addr > entry->start)
200 				lowest_addr = entry->start;
201 		}
202 	}
203 	return lowest_addr;
204 }
205 
206 /*
207  * Check continuity of segments.
208  */
209 static int
210 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
211 {
212 	int i, j, rc;
213 	struct segment_info *sort_list, *entry, temp;
214 
215 	if (dev_info->num_of_segments <= 1)
216 		return 0;
217 
218 	sort_list = kzalloc(
219 			sizeof(struct segment_info) * dev_info->num_of_segments,
220 			GFP_KERNEL);
221 	if (sort_list == NULL)
222 		return -ENOMEM;
223 	i = 0;
224 	list_for_each_entry(entry, &dev_info->seg_list, lh) {
225 		memcpy(&sort_list[i], entry, sizeof(struct segment_info));
226 		i++;
227 	}
228 
229 	/* sort segments */
230 	for (i = 0; i < dev_info->num_of_segments; i++)
231 		for (j = 0; j < dev_info->num_of_segments; j++)
232 			if (sort_list[j].start > sort_list[i].start) {
233 				memcpy(&temp, &sort_list[i],
234 					sizeof(struct segment_info));
235 				memcpy(&sort_list[i], &sort_list[j],
236 					sizeof(struct segment_info));
237 				memcpy(&sort_list[j], &temp,
238 					sizeof(struct segment_info));
239 			}
240 
241 	/* check continuity */
242 	for (i = 0; i < dev_info->num_of_segments - 1; i++) {
243 		if ((sort_list[i].end + 1) != sort_list[i+1].start) {
244 			pr_err("Adjacent DCSSs %s and %s are not "
245 			       "contiguous\n", sort_list[i].segment_name,
246 			       sort_list[i+1].segment_name);
247 			rc = -EINVAL;
248 			goto out;
249 		}
250 		/* EN and EW are allowed in a block device */
251 		if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
252 			if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
253 				(sort_list[i].segment_type == SEG_TYPE_ER) ||
254 				!(sort_list[i+1].segment_type &
255 				SEGMENT_EXCLUSIVE) ||
256 				(sort_list[i+1].segment_type == SEG_TYPE_ER)) {
257 				pr_err("DCSS %s and DCSS %s have "
258 				       "incompatible types\n",
259 				       sort_list[i].segment_name,
260 				       sort_list[i+1].segment_name);
261 				rc = -EINVAL;
262 				goto out;
263 			}
264 		}
265 	}
266 	rc = 0;
267 out:
268 	kfree(sort_list);
269 	return rc;
270 }
271 
272 /*
273  * Load a segment
274  */
275 static int
276 dcssblk_load_segment(char *name, struct segment_info **seg_info)
277 {
278 	int rc;
279 
280 	/* already loaded? */
281 	down_read(&dcssblk_devices_sem);
282 	*seg_info = dcssblk_get_segment_by_name(name);
283 	up_read(&dcssblk_devices_sem);
284 	if (*seg_info != NULL)
285 		return -EEXIST;
286 
287 	/* get a struct segment_info */
288 	*seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
289 	if (*seg_info == NULL)
290 		return -ENOMEM;
291 
292 	strcpy((*seg_info)->segment_name, name);
293 
294 	/* load the segment */
295 	rc = segment_load(name, SEGMENT_SHARED,
296 			&(*seg_info)->start, &(*seg_info)->end);
297 	if (rc < 0) {
298 		segment_warning(rc, (*seg_info)->segment_name);
299 		kfree(*seg_info);
300 	} else {
301 		INIT_LIST_HEAD(&(*seg_info)->lh);
302 		(*seg_info)->segment_type = rc;
303 	}
304 	return rc;
305 }
306 
307 /*
308  * device attribute for switching shared/nonshared (exclusive)
309  * operation (show + store)
310  */
311 static ssize_t
312 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
313 {
314 	struct dcssblk_dev_info *dev_info;
315 
316 	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
317 	return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
318 }
319 
320 static ssize_t
321 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
322 {
323 	struct dcssblk_dev_info *dev_info;
324 	struct segment_info *entry, *temp;
325 	int rc;
326 
327 	if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
328 		return -EINVAL;
329 	down_write(&dcssblk_devices_sem);
330 	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
331 	if (atomic_read(&dev_info->use_count)) {
332 		rc = -EBUSY;
333 		goto out;
334 	}
335 	if (inbuf[0] == '1') {
336 		/* reload segments in shared mode */
337 		list_for_each_entry(entry, &dev_info->seg_list, lh) {
338 			rc = segment_modify_shared(entry->segment_name,
339 						SEGMENT_SHARED);
340 			if (rc < 0) {
341 				BUG_ON(rc == -EINVAL);
342 				if (rc != -EAGAIN)
343 					goto removeseg;
344 			}
345 		}
346 		dev_info->is_shared = 1;
347 		switch (dev_info->segment_type) {
348 		case SEG_TYPE_SR:
349 		case SEG_TYPE_ER:
350 		case SEG_TYPE_SC:
351 			set_disk_ro(dev_info->gd, 1);
352 		}
353 	} else if (inbuf[0] == '0') {
354 		/* reload segments in exclusive mode */
355 		if (dev_info->segment_type == SEG_TYPE_SC) {
356 			pr_err("DCSS %s is of type SC and cannot be "
357 			       "loaded as exclusive-writable\n",
358 			       dev_info->segment_name);
359 			rc = -EINVAL;
360 			goto out;
361 		}
362 		list_for_each_entry(entry, &dev_info->seg_list, lh) {
363 			rc = segment_modify_shared(entry->segment_name,
364 						   SEGMENT_EXCLUSIVE);
365 			if (rc < 0) {
366 				BUG_ON(rc == -EINVAL);
367 				if (rc != -EAGAIN)
368 					goto removeseg;
369 			}
370 		}
371 		dev_info->is_shared = 0;
372 		set_disk_ro(dev_info->gd, 0);
373 	} else {
374 		rc = -EINVAL;
375 		goto out;
376 	}
377 	rc = count;
378 	goto out;
379 
380 removeseg:
381 	pr_err("DCSS device %s is removed after a failed access mode "
382 	       "change\n", dev_info->segment_name);
383 	temp = entry;
384 	list_for_each_entry(entry, &dev_info->seg_list, lh) {
385 		if (entry != temp)
386 			segment_unload(entry->segment_name);
387 	}
388 	list_del(&dev_info->lh);
389 
390 	del_gendisk(dev_info->gd);
391 	blk_cleanup_queue(dev_info->dcssblk_queue);
392 	dev_info->gd->queue = NULL;
393 	put_disk(dev_info->gd);
394 	up_write(&dcssblk_devices_sem);
395 
396 	if (device_remove_file_self(dev, attr)) {
397 		device_unregister(dev);
398 		put_device(dev);
399 	}
400 	return rc;
401 out:
402 	up_write(&dcssblk_devices_sem);
403 	return rc;
404 }
405 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
406 		   dcssblk_shared_store);
407 
408 /*
409  * device attribute for save operation on current copy
410  * of the segment. If the segment is busy, saving will
411  * become pending until it gets released, which can be
412  * undone by storing a non-true value to this entry.
413  * (show + store)
414  */
415 static ssize_t
416 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
417 {
418 	struct dcssblk_dev_info *dev_info;
419 
420 	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
421 	return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
422 }
423 
424 static ssize_t
425 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
426 {
427 	struct dcssblk_dev_info *dev_info;
428 	struct segment_info *entry;
429 
430 	if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
431 		return -EINVAL;
432 	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
433 
434 	down_write(&dcssblk_devices_sem);
435 	if (inbuf[0] == '1') {
436 		if (atomic_read(&dev_info->use_count) == 0) {
437 			// device is idle => we save immediately
438 			pr_info("All DCSSs that map to device %s are "
439 				"saved\n", dev_info->segment_name);
440 			list_for_each_entry(entry, &dev_info->seg_list, lh) {
441 				if (entry->segment_type == SEG_TYPE_EN ||
442 				    entry->segment_type == SEG_TYPE_SN)
443 					pr_warn("DCSS %s is of type SN or EN"
444 						" and cannot be saved\n",
445 						entry->segment_name);
446 				else
447 					segment_save(entry->segment_name);
448 			}
449 		}  else {
450 			// device is busy => we save it when it becomes
451 			// idle in dcssblk_release
452 			pr_info("Device %s is in use, its DCSSs will be "
453 				"saved when it becomes idle\n",
454 				dev_info->segment_name);
455 			dev_info->save_pending = 1;
456 		}
457 	} else if (inbuf[0] == '0') {
458 		if (dev_info->save_pending) {
459 			// device is busy & the user wants to undo his save
460 			// request
461 			dev_info->save_pending = 0;
462 			pr_info("A pending save request for device %s "
463 				"has been canceled\n",
464 				dev_info->segment_name);
465 		}
466 	} else {
467 		up_write(&dcssblk_devices_sem);
468 		return -EINVAL;
469 	}
470 	up_write(&dcssblk_devices_sem);
471 	return count;
472 }
473 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
474 		   dcssblk_save_store);
475 
476 /*
477  * device attribute for showing all segments in a device
478  */
479 static ssize_t
480 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
481 		char *buf)
482 {
483 	int i;
484 
485 	struct dcssblk_dev_info *dev_info;
486 	struct segment_info *entry;
487 
488 	down_read(&dcssblk_devices_sem);
489 	dev_info = container_of(dev, struct dcssblk_dev_info, dev);
490 	i = 0;
491 	buf[0] = '\0';
492 	list_for_each_entry(entry, &dev_info->seg_list, lh) {
493 		strcpy(&buf[i], entry->segment_name);
494 		i += strlen(entry->segment_name);
495 		buf[i] = '\n';
496 		i++;
497 	}
498 	up_read(&dcssblk_devices_sem);
499 	return i;
500 }
501 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
502 
503 static struct attribute *dcssblk_dev_attrs[] = {
504 	&dev_attr_shared.attr,
505 	&dev_attr_save.attr,
506 	&dev_attr_seglist.attr,
507 	NULL,
508 };
509 static struct attribute_group dcssblk_dev_attr_group = {
510 	.attrs = dcssblk_dev_attrs,
511 };
512 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
513 	&dcssblk_dev_attr_group,
514 	NULL,
515 };
516 
517 /*
518  * device attribute for adding devices
519  */
520 static ssize_t
521 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
522 {
523 	int rc, i, j, num_of_segments;
524 	struct dcssblk_dev_info *dev_info;
525 	struct segment_info *seg_info, *temp;
526 	char *local_buf;
527 	unsigned long seg_byte_size;
528 
529 	dev_info = NULL;
530 	seg_info = NULL;
531 	if (dev != dcssblk_root_dev) {
532 		rc = -EINVAL;
533 		goto out_nobuf;
534 	}
535 	if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
536 		rc = -ENAMETOOLONG;
537 		goto out_nobuf;
538 	}
539 
540 	local_buf = kmalloc(count + 1, GFP_KERNEL);
541 	if (local_buf == NULL) {
542 		rc = -ENOMEM;
543 		goto out_nobuf;
544 	}
545 
546 	/*
547 	 * parse input
548 	 */
549 	num_of_segments = 0;
550 	for (i = 0; ((buf[i] != '\0') && (buf[i] != '\n') && i < count); i++) {
551 		for (j = i; (buf[j] != ':') &&
552 			(buf[j] != '\0') &&
553 			(buf[j] != '\n') &&
554 			j < count; j++) {
555 			local_buf[j-i] = toupper(buf[j]);
556 		}
557 		local_buf[j-i] = '\0';
558 		if (((j - i) == 0) || ((j - i) > 8)) {
559 			rc = -ENAMETOOLONG;
560 			goto seg_list_del;
561 		}
562 
563 		rc = dcssblk_load_segment(local_buf, &seg_info);
564 		if (rc < 0)
565 			goto seg_list_del;
566 		/*
567 		 * get a struct dcssblk_dev_info
568 		 */
569 		if (num_of_segments == 0) {
570 			dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
571 					GFP_KERNEL);
572 			if (dev_info == NULL) {
573 				rc = -ENOMEM;
574 				goto out;
575 			}
576 			strcpy(dev_info->segment_name, local_buf);
577 			dev_info->segment_type = seg_info->segment_type;
578 			INIT_LIST_HEAD(&dev_info->seg_list);
579 		}
580 		list_add_tail(&seg_info->lh, &dev_info->seg_list);
581 		num_of_segments++;
582 		i = j;
583 
584 		if ((buf[j] == '\0') || (buf[j] == '\n'))
585 			break;
586 	}
587 
588 	/* no trailing colon at the end of the input */
589 	if ((i > 0) && (buf[i-1] == ':')) {
590 		rc = -ENAMETOOLONG;
591 		goto seg_list_del;
592 	}
593 	strlcpy(local_buf, buf, i + 1);
594 	dev_info->num_of_segments = num_of_segments;
595 	rc = dcssblk_is_continuous(dev_info);
596 	if (rc < 0)
597 		goto seg_list_del;
598 
599 	dev_info->start = dcssblk_find_lowest_addr(dev_info);
600 	dev_info->end = dcssblk_find_highest_addr(dev_info);
601 
602 	dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
603 	dev_info->dev.release = dcssblk_release_segment;
604 	dev_info->dev.groups = dcssblk_dev_attr_groups;
605 	INIT_LIST_HEAD(&dev_info->lh);
606 	dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
607 	if (dev_info->gd == NULL) {
608 		rc = -ENOMEM;
609 		goto seg_list_del;
610 	}
611 	dev_info->gd->major = dcssblk_major;
612 	dev_info->gd->fops = &dcssblk_devops;
613 	dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
614 	dev_info->gd->queue = dev_info->dcssblk_queue;
615 	dev_info->gd->private_data = dev_info;
616 	dev_info->gd->driverfs_dev = &dev_info->dev;
617 	blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
618 	blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
619 
620 	seg_byte_size = (dev_info->end - dev_info->start + 1);
621 	set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
622 	pr_info("Loaded %s with total size %lu bytes and capacity %lu "
623 		"sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
624 
625 	dev_info->save_pending = 0;
626 	dev_info->is_shared = 1;
627 	dev_info->dev.parent = dcssblk_root_dev;
628 
629 	/*
630 	 *get minor, add to list
631 	 */
632 	down_write(&dcssblk_devices_sem);
633 	if (dcssblk_get_segment_by_name(local_buf)) {
634 		rc = -EEXIST;
635 		goto release_gd;
636 	}
637 	rc = dcssblk_assign_free_minor(dev_info);
638 	if (rc)
639 		goto release_gd;
640 	sprintf(dev_info->gd->disk_name, "dcssblk%d",
641 		dev_info->gd->first_minor);
642 	list_add_tail(&dev_info->lh, &dcssblk_devices);
643 
644 	if (!try_module_get(THIS_MODULE)) {
645 		rc = -ENODEV;
646 		goto dev_list_del;
647 	}
648 	/*
649 	 * register the device
650 	 */
651 	rc = device_register(&dev_info->dev);
652 	if (rc)
653 		goto put_dev;
654 
655 	get_device(&dev_info->dev);
656 	add_disk(dev_info->gd);
657 
658 	switch (dev_info->segment_type) {
659 		case SEG_TYPE_SR:
660 		case SEG_TYPE_ER:
661 		case SEG_TYPE_SC:
662 			set_disk_ro(dev_info->gd,1);
663 			break;
664 		default:
665 			set_disk_ro(dev_info->gd,0);
666 			break;
667 	}
668 	up_write(&dcssblk_devices_sem);
669 	rc = count;
670 	goto out;
671 
672 put_dev:
673 	list_del(&dev_info->lh);
674 	blk_cleanup_queue(dev_info->dcssblk_queue);
675 	dev_info->gd->queue = NULL;
676 	put_disk(dev_info->gd);
677 	list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
678 		segment_unload(seg_info->segment_name);
679 	}
680 	put_device(&dev_info->dev);
681 	up_write(&dcssblk_devices_sem);
682 	goto out;
683 dev_list_del:
684 	list_del(&dev_info->lh);
685 release_gd:
686 	blk_cleanup_queue(dev_info->dcssblk_queue);
687 	dev_info->gd->queue = NULL;
688 	put_disk(dev_info->gd);
689 	up_write(&dcssblk_devices_sem);
690 seg_list_del:
691 	if (dev_info == NULL)
692 		goto out;
693 	list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
694 		list_del(&seg_info->lh);
695 		segment_unload(seg_info->segment_name);
696 		kfree(seg_info);
697 	}
698 	kfree(dev_info);
699 out:
700 	kfree(local_buf);
701 out_nobuf:
702 	return rc;
703 }
704 
705 /*
706  * device attribute for removing devices
707  */
708 static ssize_t
709 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
710 {
711 	struct dcssblk_dev_info *dev_info;
712 	struct segment_info *entry;
713 	int rc, i;
714 	char *local_buf;
715 
716 	if (dev != dcssblk_root_dev) {
717 		return -EINVAL;
718 	}
719 	local_buf = kmalloc(count + 1, GFP_KERNEL);
720 	if (local_buf == NULL) {
721 		return -ENOMEM;
722 	}
723 	/*
724 	 * parse input
725 	 */
726 	for (i = 0; ((*(buf+i)!='\0') && (*(buf+i)!='\n') && i < count); i++) {
727 		local_buf[i] = toupper(buf[i]);
728 	}
729 	local_buf[i] = '\0';
730 	if ((i == 0) || (i > 8)) {
731 		rc = -ENAMETOOLONG;
732 		goto out_buf;
733 	}
734 
735 	down_write(&dcssblk_devices_sem);
736 	dev_info = dcssblk_get_device_by_name(local_buf);
737 	if (dev_info == NULL) {
738 		up_write(&dcssblk_devices_sem);
739 		pr_warning("Device %s cannot be removed because it is not a "
740 			   "known device\n", local_buf);
741 		rc = -ENODEV;
742 		goto out_buf;
743 	}
744 	if (atomic_read(&dev_info->use_count) != 0) {
745 		up_write(&dcssblk_devices_sem);
746 		pr_warning("Device %s cannot be removed while it is in "
747 			   "use\n", local_buf);
748 		rc = -EBUSY;
749 		goto out_buf;
750 	}
751 
752 	list_del(&dev_info->lh);
753 	del_gendisk(dev_info->gd);
754 	blk_cleanup_queue(dev_info->dcssblk_queue);
755 	dev_info->gd->queue = NULL;
756 	put_disk(dev_info->gd);
757 	device_unregister(&dev_info->dev);
758 
759 	/* unload all related segments */
760 	list_for_each_entry(entry, &dev_info->seg_list, lh)
761 		segment_unload(entry->segment_name);
762 
763 	put_device(&dev_info->dev);
764 	up_write(&dcssblk_devices_sem);
765 
766 	rc = count;
767 out_buf:
768 	kfree(local_buf);
769 	return rc;
770 }
771 
772 static int
773 dcssblk_open(struct block_device *bdev, fmode_t mode)
774 {
775 	struct dcssblk_dev_info *dev_info;
776 	int rc;
777 
778 	dev_info = bdev->bd_disk->private_data;
779 	if (NULL == dev_info) {
780 		rc = -ENODEV;
781 		goto out;
782 	}
783 	atomic_inc(&dev_info->use_count);
784 	bdev->bd_block_size = 4096;
785 	rc = 0;
786 out:
787 	return rc;
788 }
789 
790 static void
791 dcssblk_release(struct gendisk *disk, fmode_t mode)
792 {
793 	struct dcssblk_dev_info *dev_info = disk->private_data;
794 	struct segment_info *entry;
795 
796 	if (!dev_info) {
797 		WARN_ON(1);
798 		return;
799 	}
800 	down_write(&dcssblk_devices_sem);
801 	if (atomic_dec_and_test(&dev_info->use_count)
802 	    && (dev_info->save_pending)) {
803 		pr_info("Device %s has become idle and is being saved "
804 			"now\n", dev_info->segment_name);
805 		list_for_each_entry(entry, &dev_info->seg_list, lh) {
806 			if (entry->segment_type == SEG_TYPE_EN ||
807 			    entry->segment_type == SEG_TYPE_SN)
808 				pr_warn("DCSS %s is of type SN or EN and cannot"
809 					" be saved\n", entry->segment_name);
810 			else
811 				segment_save(entry->segment_name);
812 		}
813 		dev_info->save_pending = 0;
814 	}
815 	up_write(&dcssblk_devices_sem);
816 }
817 
818 static void
819 dcssblk_make_request(struct request_queue *q, struct bio *bio)
820 {
821 	struct dcssblk_dev_info *dev_info;
822 	struct bio_vec bvec;
823 	struct bvec_iter iter;
824 	unsigned long index;
825 	unsigned long page_addr;
826 	unsigned long source_addr;
827 	unsigned long bytes_done;
828 
829 	bytes_done = 0;
830 	dev_info = bio->bi_bdev->bd_disk->private_data;
831 	if (dev_info == NULL)
832 		goto fail;
833 	if ((bio->bi_iter.bi_sector & 7) != 0 ||
834 	    (bio->bi_iter.bi_size & 4095) != 0)
835 		/* Request is not page-aligned. */
836 		goto fail;
837 	if (bio_end_sector(bio) > get_capacity(bio->bi_bdev->bd_disk)) {
838 		/* Request beyond end of DCSS segment. */
839 		goto fail;
840 	}
841 	/* verify data transfer direction */
842 	if (dev_info->is_shared) {
843 		switch (dev_info->segment_type) {
844 		case SEG_TYPE_SR:
845 		case SEG_TYPE_ER:
846 		case SEG_TYPE_SC:
847 			/* cannot write to these segments */
848 			if (bio_data_dir(bio) == WRITE) {
849 				pr_warning("Writing to %s failed because it "
850 					   "is a read-only device\n",
851 					   dev_name(&dev_info->dev));
852 				goto fail;
853 			}
854 		}
855 	}
856 
857 	index = (bio->bi_iter.bi_sector >> 3);
858 	bio_for_each_segment(bvec, bio, iter) {
859 		page_addr = (unsigned long)
860 			page_address(bvec.bv_page) + bvec.bv_offset;
861 		source_addr = dev_info->start + (index<<12) + bytes_done;
862 		if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
863 			// More paranoia.
864 			goto fail;
865 		if (bio_data_dir(bio) == READ) {
866 			memcpy((void*)page_addr, (void*)source_addr,
867 				bvec.bv_len);
868 		} else {
869 			memcpy((void*)source_addr, (void*)page_addr,
870 				bvec.bv_len);
871 		}
872 		bytes_done += bvec.bv_len;
873 	}
874 	bio_endio(bio, 0);
875 	return;
876 fail:
877 	bio_io_error(bio);
878 }
879 
880 static long
881 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
882 			void **kaddr, unsigned long *pfn, long size)
883 {
884 	struct dcssblk_dev_info *dev_info;
885 	unsigned long offset, dev_sz;
886 
887 	dev_info = bdev->bd_disk->private_data;
888 	if (!dev_info)
889 		return -ENODEV;
890 	dev_sz = dev_info->end - dev_info->start;
891 	offset = secnum * 512;
892 	*kaddr = (void *) (dev_info->start + offset);
893 	*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
894 
895 	return dev_sz - offset;
896 }
897 
898 static void
899 dcssblk_check_params(void)
900 {
901 	int rc, i, j, k;
902 	char buf[DCSSBLK_PARM_LEN + 1];
903 	struct dcssblk_dev_info *dev_info;
904 
905 	for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
906 	     i++) {
907 		for (j = i; (dcssblk_segments[j] != ',')  &&
908 			    (dcssblk_segments[j] != '\0') &&
909 			    (dcssblk_segments[j] != '(')  &&
910 			    (j < DCSSBLK_PARM_LEN); j++)
911 		{
912 			buf[j-i] = dcssblk_segments[j];
913 		}
914 		buf[j-i] = '\0';
915 		rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
916 		if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
917 			for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
918 				buf[k] = toupper(buf[k]);
919 			buf[k] = '\0';
920 			if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
921 				down_read(&dcssblk_devices_sem);
922 				dev_info = dcssblk_get_device_by_name(buf);
923 				up_read(&dcssblk_devices_sem);
924 				if (dev_info)
925 					dcssblk_shared_store(&dev_info->dev,
926 							     NULL, "0\n", 2);
927 			}
928 		}
929 		while ((dcssblk_segments[j] != ',') &&
930 		       (dcssblk_segments[j] != '\0'))
931 		{
932 			j++;
933 		}
934 		if (dcssblk_segments[j] == '\0')
935 			break;
936 		i = j;
937 	}
938 }
939 
940 /*
941  * Suspend / Resume
942  */
943 static int dcssblk_freeze(struct device *dev)
944 {
945 	struct dcssblk_dev_info *dev_info;
946 	int rc = 0;
947 
948 	list_for_each_entry(dev_info, &dcssblk_devices, lh) {
949 		switch (dev_info->segment_type) {
950 			case SEG_TYPE_SR:
951 			case SEG_TYPE_ER:
952 			case SEG_TYPE_SC:
953 				if (!dev_info->is_shared)
954 					rc = -EINVAL;
955 				break;
956 			default:
957 				rc = -EINVAL;
958 				break;
959 		}
960 		if (rc)
961 			break;
962 	}
963 	if (rc)
964 		pr_err("Suspending the system failed because DCSS device %s "
965 		       "is writable\n",
966 		       dev_info->segment_name);
967 	return rc;
968 }
969 
970 static int dcssblk_restore(struct device *dev)
971 {
972 	struct dcssblk_dev_info *dev_info;
973 	struct segment_info *entry;
974 	unsigned long start, end;
975 	int rc = 0;
976 
977 	list_for_each_entry(dev_info, &dcssblk_devices, lh) {
978 		list_for_each_entry(entry, &dev_info->seg_list, lh) {
979 			segment_unload(entry->segment_name);
980 			rc = segment_load(entry->segment_name, SEGMENT_SHARED,
981 					  &start, &end);
982 			if (rc < 0) {
983 // TODO in_use check ?
984 				segment_warning(rc, entry->segment_name);
985 				goto out_panic;
986 			}
987 			if (start != entry->start || end != entry->end) {
988 				pr_err("The address range of DCSS %s changed "
989 				       "while the system was suspended\n",
990 				       entry->segment_name);
991 				goto out_panic;
992 			}
993 		}
994 	}
995 	return 0;
996 out_panic:
997 	panic("fatal dcssblk resume error\n");
998 }
999 
1000 static int dcssblk_thaw(struct device *dev)
1001 {
1002 	return 0;
1003 }
1004 
1005 static const struct dev_pm_ops dcssblk_pm_ops = {
1006 	.freeze		= dcssblk_freeze,
1007 	.thaw		= dcssblk_thaw,
1008 	.restore	= dcssblk_restore,
1009 };
1010 
1011 static struct platform_driver dcssblk_pdrv = {
1012 	.driver = {
1013 		.name	= "dcssblk",
1014 		.pm	= &dcssblk_pm_ops,
1015 	},
1016 };
1017 
1018 static struct platform_device *dcssblk_pdev;
1019 
1020 
1021 /*
1022  * The init/exit functions.
1023  */
1024 static void __exit
1025 dcssblk_exit(void)
1026 {
1027 	platform_device_unregister(dcssblk_pdev);
1028 	platform_driver_unregister(&dcssblk_pdrv);
1029 	root_device_unregister(dcssblk_root_dev);
1030 	unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1031 }
1032 
1033 static int __init
1034 dcssblk_init(void)
1035 {
1036 	int rc;
1037 
1038 	rc = platform_driver_register(&dcssblk_pdrv);
1039 	if (rc)
1040 		return rc;
1041 
1042 	dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1043 							0);
1044 	if (IS_ERR(dcssblk_pdev)) {
1045 		rc = PTR_ERR(dcssblk_pdev);
1046 		goto out_pdrv;
1047 	}
1048 
1049 	dcssblk_root_dev = root_device_register("dcssblk");
1050 	if (IS_ERR(dcssblk_root_dev)) {
1051 		rc = PTR_ERR(dcssblk_root_dev);
1052 		goto out_pdev;
1053 	}
1054 	rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1055 	if (rc)
1056 		goto out_root;
1057 	rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1058 	if (rc)
1059 		goto out_root;
1060 	rc = register_blkdev(0, DCSSBLK_NAME);
1061 	if (rc < 0)
1062 		goto out_root;
1063 	dcssblk_major = rc;
1064 	init_rwsem(&dcssblk_devices_sem);
1065 
1066 	dcssblk_check_params();
1067 	return 0;
1068 
1069 out_root:
1070 	root_device_unregister(dcssblk_root_dev);
1071 out_pdev:
1072 	platform_device_unregister(dcssblk_pdev);
1073 out_pdrv:
1074 	platform_driver_unregister(&dcssblk_pdrv);
1075 	return rc;
1076 }
1077 
1078 module_init(dcssblk_init);
1079 module_exit(dcssblk_exit);
1080 
1081 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1082 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1083 		 "comma-separated list, names in each set separated "
1084 		 "by commas are separated by colons, each set contains "
1085 		 "names of contiguous segments and each name max. 8 chars.\n"
1086 		 "Adding \"(local)\" to the end of each set equals echoing 0 "
1087 		 "to /sys/devices/dcssblk/<device name>/shared after loading "
1088 		 "the contiguous segments - \n"
1089 		 "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1090 
1091 MODULE_LICENSE("GPL");
1092