xref: /linux/drivers/s390/block/scm_blk.c (revision 4413e16d9d21673bb5048a2e542f1aaa00015c2e)
1 /*
2  * Block driver for s390 storage class memory.
3  *
4  * Copyright IBM Corp. 2012
5  * Author(s): Sebastian Ott <sebott@linux.vnet.ibm.com>
6  */
7 
8 #define KMSG_COMPONENT "scm_block"
9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
10 
11 #include <linux/interrupt.h>
12 #include <linux/spinlock.h>
13 #include <linux/module.h>
14 #include <linux/blkdev.h>
15 #include <linux/genhd.h>
16 #include <linux/slab.h>
17 #include <linux/list.h>
18 #include <asm/eadm.h>
19 #include "scm_blk.h"
20 
21 debug_info_t *scm_debug;
22 static int scm_major;
23 static DEFINE_SPINLOCK(list_lock);
24 static LIST_HEAD(inactive_requests);
25 static unsigned int nr_requests = 64;
26 static atomic_t nr_devices = ATOMIC_INIT(0);
27 module_param(nr_requests, uint, S_IRUGO);
28 MODULE_PARM_DESC(nr_requests, "Number of parallel requests.");
29 
30 MODULE_DESCRIPTION("Block driver for s390 storage class memory.");
31 MODULE_LICENSE("GPL");
32 MODULE_ALIAS("scm:scmdev*");
33 
34 static void __scm_free_rq(struct scm_request *scmrq)
35 {
36 	struct aob_rq_header *aobrq = to_aobrq(scmrq);
37 
38 	free_page((unsigned long) scmrq->aob);
39 	free_page((unsigned long) scmrq->aidaw);
40 	__scm_free_rq_cluster(scmrq);
41 	kfree(aobrq);
42 }
43 
44 static void scm_free_rqs(void)
45 {
46 	struct list_head *iter, *safe;
47 	struct scm_request *scmrq;
48 
49 	spin_lock_irq(&list_lock);
50 	list_for_each_safe(iter, safe, &inactive_requests) {
51 		scmrq = list_entry(iter, struct scm_request, list);
52 		list_del(&scmrq->list);
53 		__scm_free_rq(scmrq);
54 	}
55 	spin_unlock_irq(&list_lock);
56 }
57 
58 static int __scm_alloc_rq(void)
59 {
60 	struct aob_rq_header *aobrq;
61 	struct scm_request *scmrq;
62 
63 	aobrq = kzalloc(sizeof(*aobrq) + sizeof(*scmrq), GFP_KERNEL);
64 	if (!aobrq)
65 		return -ENOMEM;
66 
67 	scmrq = (void *) aobrq->data;
68 	scmrq->aidaw = (void *) get_zeroed_page(GFP_DMA);
69 	scmrq->aob = (void *) get_zeroed_page(GFP_DMA);
70 	if (!scmrq->aob || !scmrq->aidaw) {
71 		__scm_free_rq(scmrq);
72 		return -ENOMEM;
73 	}
74 
75 	if (__scm_alloc_rq_cluster(scmrq)) {
76 		__scm_free_rq(scmrq);
77 		return -ENOMEM;
78 	}
79 
80 	INIT_LIST_HEAD(&scmrq->list);
81 	spin_lock_irq(&list_lock);
82 	list_add(&scmrq->list, &inactive_requests);
83 	spin_unlock_irq(&list_lock);
84 
85 	return 0;
86 }
87 
88 static int scm_alloc_rqs(unsigned int nrqs)
89 {
90 	int ret = 0;
91 
92 	while (nrqs-- && !ret)
93 		ret = __scm_alloc_rq();
94 
95 	return ret;
96 }
97 
98 static struct scm_request *scm_request_fetch(void)
99 {
100 	struct scm_request *scmrq = NULL;
101 
102 	spin_lock(&list_lock);
103 	if (list_empty(&inactive_requests))
104 		goto out;
105 	scmrq = list_first_entry(&inactive_requests, struct scm_request, list);
106 	list_del(&scmrq->list);
107 out:
108 	spin_unlock(&list_lock);
109 	return scmrq;
110 }
111 
112 static void scm_request_done(struct scm_request *scmrq)
113 {
114 	unsigned long flags;
115 
116 	spin_lock_irqsave(&list_lock, flags);
117 	list_add(&scmrq->list, &inactive_requests);
118 	spin_unlock_irqrestore(&list_lock, flags);
119 }
120 
121 static int scm_open(struct block_device *blkdev, fmode_t mode)
122 {
123 	return scm_get_ref();
124 }
125 
126 static int scm_release(struct gendisk *gendisk, fmode_t mode)
127 {
128 	scm_put_ref();
129 	return 0;
130 }
131 
132 static const struct block_device_operations scm_blk_devops = {
133 	.owner = THIS_MODULE,
134 	.open = scm_open,
135 	.release = scm_release,
136 };
137 
138 static void scm_request_prepare(struct scm_request *scmrq)
139 {
140 	struct scm_blk_dev *bdev = scmrq->bdev;
141 	struct scm_device *scmdev = bdev->gendisk->private_data;
142 	struct aidaw *aidaw = scmrq->aidaw;
143 	struct msb *msb = &scmrq->aob->msb[0];
144 	struct req_iterator iter;
145 	struct bio_vec *bv;
146 
147 	msb->bs = MSB_BS_4K;
148 	scmrq->aob->request.msb_count = 1;
149 	msb->scm_addr = scmdev->address +
150 		((u64) blk_rq_pos(scmrq->request) << 9);
151 	msb->oc = (rq_data_dir(scmrq->request) == READ) ?
152 		MSB_OC_READ : MSB_OC_WRITE;
153 	msb->flags |= MSB_FLAG_IDA;
154 	msb->data_addr = (u64) aidaw;
155 
156 	rq_for_each_segment(bv, scmrq->request, iter) {
157 		WARN_ON(bv->bv_offset);
158 		msb->blk_count += bv->bv_len >> 12;
159 		aidaw->data_addr = (u64) page_address(bv->bv_page);
160 		aidaw++;
161 	}
162 }
163 
164 static inline void scm_request_init(struct scm_blk_dev *bdev,
165 				    struct scm_request *scmrq,
166 				    struct request *req)
167 {
168 	struct aob_rq_header *aobrq = to_aobrq(scmrq);
169 	struct aob *aob = scmrq->aob;
170 
171 	memset(aob, 0, sizeof(*aob));
172 	memset(scmrq->aidaw, 0, PAGE_SIZE);
173 	aobrq->scmdev = bdev->scmdev;
174 	aob->request.cmd_code = ARQB_CMD_MOVE;
175 	aob->request.data = (u64) aobrq;
176 	scmrq->request = req;
177 	scmrq->bdev = bdev;
178 	scmrq->retries = 4;
179 	scmrq->error = 0;
180 	scm_request_cluster_init(scmrq);
181 }
182 
183 static void scm_ensure_queue_restart(struct scm_blk_dev *bdev)
184 {
185 	if (atomic_read(&bdev->queued_reqs)) {
186 		/* Queue restart is triggered by the next interrupt. */
187 		return;
188 	}
189 	blk_delay_queue(bdev->rq, SCM_QUEUE_DELAY);
190 }
191 
192 void scm_request_requeue(struct scm_request *scmrq)
193 {
194 	struct scm_blk_dev *bdev = scmrq->bdev;
195 
196 	scm_release_cluster(scmrq);
197 	blk_requeue_request(bdev->rq, scmrq->request);
198 	scm_request_done(scmrq);
199 	scm_ensure_queue_restart(bdev);
200 }
201 
202 void scm_request_finish(struct scm_request *scmrq)
203 {
204 	scm_release_cluster(scmrq);
205 	blk_end_request_all(scmrq->request, scmrq->error);
206 	scm_request_done(scmrq);
207 }
208 
209 static void scm_blk_request(struct request_queue *rq)
210 {
211 	struct scm_device *scmdev = rq->queuedata;
212 	struct scm_blk_dev *bdev = dev_get_drvdata(&scmdev->dev);
213 	struct scm_request *scmrq;
214 	struct request *req;
215 	int ret;
216 
217 	while ((req = blk_peek_request(rq))) {
218 		if (req->cmd_type != REQ_TYPE_FS)
219 			continue;
220 
221 		scmrq = scm_request_fetch();
222 		if (!scmrq) {
223 			SCM_LOG(5, "no request");
224 			scm_ensure_queue_restart(bdev);
225 			return;
226 		}
227 		scm_request_init(bdev, scmrq, req);
228 		if (!scm_reserve_cluster(scmrq)) {
229 			SCM_LOG(5, "cluster busy");
230 			scm_request_done(scmrq);
231 			return;
232 		}
233 		if (scm_need_cluster_request(scmrq)) {
234 			blk_start_request(req);
235 			scm_initiate_cluster_request(scmrq);
236 			return;
237 		}
238 		scm_request_prepare(scmrq);
239 		blk_start_request(req);
240 
241 		ret = scm_start_aob(scmrq->aob);
242 		if (ret) {
243 			SCM_LOG(5, "no subchannel");
244 			scm_request_requeue(scmrq);
245 			return;
246 		}
247 		atomic_inc(&bdev->queued_reqs);
248 	}
249 }
250 
251 static void __scmrq_log_error(struct scm_request *scmrq)
252 {
253 	struct aob *aob = scmrq->aob;
254 
255 	if (scmrq->error == -ETIMEDOUT)
256 		SCM_LOG(1, "Request timeout");
257 	else {
258 		SCM_LOG(1, "Request error");
259 		SCM_LOG_HEX(1, &aob->response, sizeof(aob->response));
260 	}
261 	if (scmrq->retries)
262 		SCM_LOG(1, "Retry request");
263 	else
264 		pr_err("An I/O operation to SCM failed with rc=%d\n",
265 		       scmrq->error);
266 }
267 
268 void scm_blk_irq(struct scm_device *scmdev, void *data, int error)
269 {
270 	struct scm_request *scmrq = data;
271 	struct scm_blk_dev *bdev = scmrq->bdev;
272 
273 	scmrq->error = error;
274 	if (error)
275 		__scmrq_log_error(scmrq);
276 
277 	spin_lock(&bdev->lock);
278 	list_add_tail(&scmrq->list, &bdev->finished_requests);
279 	spin_unlock(&bdev->lock);
280 	tasklet_hi_schedule(&bdev->tasklet);
281 }
282 
283 static void scm_blk_tasklet(struct scm_blk_dev *bdev)
284 {
285 	struct scm_request *scmrq;
286 	unsigned long flags;
287 
288 	spin_lock_irqsave(&bdev->lock, flags);
289 	while (!list_empty(&bdev->finished_requests)) {
290 		scmrq = list_first_entry(&bdev->finished_requests,
291 					 struct scm_request, list);
292 		list_del(&scmrq->list);
293 		spin_unlock_irqrestore(&bdev->lock, flags);
294 
295 		if (scmrq->error && scmrq->retries-- > 0) {
296 			if (scm_start_aob(scmrq->aob)) {
297 				spin_lock_irqsave(&bdev->rq_lock, flags);
298 				scm_request_requeue(scmrq);
299 				spin_unlock_irqrestore(&bdev->rq_lock, flags);
300 			}
301 			/* Request restarted or requeued, handle next. */
302 			spin_lock_irqsave(&bdev->lock, flags);
303 			continue;
304 		}
305 
306 		if (scm_test_cluster_request(scmrq)) {
307 			scm_cluster_request_irq(scmrq);
308 			spin_lock_irqsave(&bdev->lock, flags);
309 			continue;
310 		}
311 
312 		scm_request_finish(scmrq);
313 		atomic_dec(&bdev->queued_reqs);
314 		spin_lock_irqsave(&bdev->lock, flags);
315 	}
316 	spin_unlock_irqrestore(&bdev->lock, flags);
317 	/* Look out for more requests. */
318 	blk_run_queue(bdev->rq);
319 }
320 
321 int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
322 {
323 	struct request_queue *rq;
324 	int len, ret = -ENOMEM;
325 	unsigned int devindex, nr_max_blk;
326 
327 	devindex = atomic_inc_return(&nr_devices) - 1;
328 	/* scma..scmz + scmaa..scmzz */
329 	if (devindex > 701) {
330 		ret = -ENODEV;
331 		goto out;
332 	}
333 
334 	bdev->scmdev = scmdev;
335 	spin_lock_init(&bdev->rq_lock);
336 	spin_lock_init(&bdev->lock);
337 	INIT_LIST_HEAD(&bdev->finished_requests);
338 	atomic_set(&bdev->queued_reqs, 0);
339 	tasklet_init(&bdev->tasklet,
340 		     (void (*)(unsigned long)) scm_blk_tasklet,
341 		     (unsigned long) bdev);
342 
343 	rq = blk_init_queue(scm_blk_request, &bdev->rq_lock);
344 	if (!rq)
345 		goto out;
346 
347 	bdev->rq = rq;
348 	nr_max_blk = min(scmdev->nr_max_block,
349 			 (unsigned int) (PAGE_SIZE / sizeof(struct aidaw)));
350 
351 	blk_queue_logical_block_size(rq, 1 << 12);
352 	blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */
353 	blk_queue_max_segments(rq, nr_max_blk);
354 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rq);
355 	scm_blk_dev_cluster_setup(bdev);
356 
357 	bdev->gendisk = alloc_disk(SCM_NR_PARTS);
358 	if (!bdev->gendisk)
359 		goto out_queue;
360 
361 	rq->queuedata = scmdev;
362 	bdev->gendisk->driverfs_dev = &scmdev->dev;
363 	bdev->gendisk->private_data = scmdev;
364 	bdev->gendisk->fops = &scm_blk_devops;
365 	bdev->gendisk->queue = rq;
366 	bdev->gendisk->major = scm_major;
367 	bdev->gendisk->first_minor = devindex * SCM_NR_PARTS;
368 
369 	len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm");
370 	if (devindex > 25) {
371 		len += snprintf(bdev->gendisk->disk_name + len,
372 				DISK_NAME_LEN - len, "%c",
373 				'a' + (devindex / 26) - 1);
374 		devindex = devindex % 26;
375 	}
376 	snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c",
377 		 'a' + devindex);
378 
379 	/* 512 byte sectors */
380 	set_capacity(bdev->gendisk, scmdev->size >> 9);
381 	add_disk(bdev->gendisk);
382 	return 0;
383 
384 out_queue:
385 	blk_cleanup_queue(rq);
386 out:
387 	atomic_dec(&nr_devices);
388 	return ret;
389 }
390 
391 void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
392 {
393 	tasklet_kill(&bdev->tasklet);
394 	del_gendisk(bdev->gendisk);
395 	blk_cleanup_queue(bdev->gendisk->queue);
396 	put_disk(bdev->gendisk);
397 }
398 
399 static int __init scm_blk_init(void)
400 {
401 	int ret = -EINVAL;
402 
403 	if (!scm_cluster_size_valid())
404 		goto out;
405 
406 	ret = register_blkdev(0, "scm");
407 	if (ret < 0)
408 		goto out;
409 
410 	scm_major = ret;
411 	if (scm_alloc_rqs(nr_requests))
412 		goto out_unreg;
413 
414 	scm_debug = debug_register("scm_log", 16, 1, 16);
415 	if (!scm_debug)
416 		goto out_free;
417 
418 	debug_register_view(scm_debug, &debug_hex_ascii_view);
419 	debug_set_level(scm_debug, 2);
420 
421 	ret = scm_drv_init();
422 	if (ret)
423 		goto out_dbf;
424 
425 	return ret;
426 
427 out_dbf:
428 	debug_unregister(scm_debug);
429 out_free:
430 	scm_free_rqs();
431 out_unreg:
432 	unregister_blkdev(scm_major, "scm");
433 out:
434 	return ret;
435 }
436 module_init(scm_blk_init);
437 
438 static void __exit scm_blk_cleanup(void)
439 {
440 	scm_drv_cleanup();
441 	debug_unregister(scm_debug);
442 	scm_free_rqs();
443 	unregister_blkdev(scm_major, "scm");
444 }
445 module_exit(scm_blk_cleanup);
446