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 void scm_release(struct gendisk *gendisk, fmode_t mode) 127 { 128 scm_put_ref(); 129 } 130 131 static const struct block_device_operations scm_blk_devops = { 132 .owner = THIS_MODULE, 133 .open = scm_open, 134 .release = scm_release, 135 }; 136 137 static bool scm_permit_request(struct scm_blk_dev *bdev, struct request *req) 138 { 139 return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT; 140 } 141 142 static void scm_request_prepare(struct scm_request *scmrq) 143 { 144 struct scm_blk_dev *bdev = scmrq->bdev; 145 struct scm_device *scmdev = bdev->gendisk->private_data; 146 struct aidaw *aidaw = scmrq->aidaw; 147 struct msb *msb = &scmrq->aob->msb[0]; 148 struct req_iterator iter; 149 struct bio_vec *bv; 150 151 msb->bs = MSB_BS_4K; 152 scmrq->aob->request.msb_count = 1; 153 msb->scm_addr = scmdev->address + 154 ((u64) blk_rq_pos(scmrq->request) << 9); 155 msb->oc = (rq_data_dir(scmrq->request) == READ) ? 156 MSB_OC_READ : MSB_OC_WRITE; 157 msb->flags |= MSB_FLAG_IDA; 158 msb->data_addr = (u64) aidaw; 159 160 rq_for_each_segment(bv, scmrq->request, iter) { 161 WARN_ON(bv->bv_offset); 162 msb->blk_count += bv->bv_len >> 12; 163 aidaw->data_addr = (u64) page_address(bv->bv_page); 164 aidaw++; 165 } 166 } 167 168 static inline void scm_request_init(struct scm_blk_dev *bdev, 169 struct scm_request *scmrq, 170 struct request *req) 171 { 172 struct aob_rq_header *aobrq = to_aobrq(scmrq); 173 struct aob *aob = scmrq->aob; 174 175 memset(aob, 0, sizeof(*aob)); 176 memset(scmrq->aidaw, 0, PAGE_SIZE); 177 aobrq->scmdev = bdev->scmdev; 178 aob->request.cmd_code = ARQB_CMD_MOVE; 179 aob->request.data = (u64) aobrq; 180 scmrq->request = req; 181 scmrq->bdev = bdev; 182 scmrq->retries = 4; 183 scmrq->error = 0; 184 scm_request_cluster_init(scmrq); 185 } 186 187 static void scm_ensure_queue_restart(struct scm_blk_dev *bdev) 188 { 189 if (atomic_read(&bdev->queued_reqs)) { 190 /* Queue restart is triggered by the next interrupt. */ 191 return; 192 } 193 blk_delay_queue(bdev->rq, SCM_QUEUE_DELAY); 194 } 195 196 void scm_request_requeue(struct scm_request *scmrq) 197 { 198 struct scm_blk_dev *bdev = scmrq->bdev; 199 200 scm_release_cluster(scmrq); 201 blk_requeue_request(bdev->rq, scmrq->request); 202 atomic_dec(&bdev->queued_reqs); 203 scm_request_done(scmrq); 204 scm_ensure_queue_restart(bdev); 205 } 206 207 void scm_request_finish(struct scm_request *scmrq) 208 { 209 struct scm_blk_dev *bdev = scmrq->bdev; 210 211 scm_release_cluster(scmrq); 212 blk_end_request_all(scmrq->request, scmrq->error); 213 atomic_dec(&bdev->queued_reqs); 214 scm_request_done(scmrq); 215 } 216 217 static void scm_blk_request(struct request_queue *rq) 218 { 219 struct scm_device *scmdev = rq->queuedata; 220 struct scm_blk_dev *bdev = dev_get_drvdata(&scmdev->dev); 221 struct scm_request *scmrq; 222 struct request *req; 223 int ret; 224 225 while ((req = blk_peek_request(rq))) { 226 if (req->cmd_type != REQ_TYPE_FS) 227 continue; 228 229 if (!scm_permit_request(bdev, req)) { 230 scm_ensure_queue_restart(bdev); 231 return; 232 } 233 scmrq = scm_request_fetch(); 234 if (!scmrq) { 235 SCM_LOG(5, "no request"); 236 scm_ensure_queue_restart(bdev); 237 return; 238 } 239 scm_request_init(bdev, scmrq, req); 240 if (!scm_reserve_cluster(scmrq)) { 241 SCM_LOG(5, "cluster busy"); 242 scm_request_done(scmrq); 243 return; 244 } 245 if (scm_need_cluster_request(scmrq)) { 246 atomic_inc(&bdev->queued_reqs); 247 blk_start_request(req); 248 scm_initiate_cluster_request(scmrq); 249 return; 250 } 251 scm_request_prepare(scmrq); 252 atomic_inc(&bdev->queued_reqs); 253 blk_start_request(req); 254 255 ret = scm_start_aob(scmrq->aob); 256 if (ret) { 257 SCM_LOG(5, "no subchannel"); 258 scm_request_requeue(scmrq); 259 return; 260 } 261 } 262 } 263 264 static void __scmrq_log_error(struct scm_request *scmrq) 265 { 266 struct aob *aob = scmrq->aob; 267 268 if (scmrq->error == -ETIMEDOUT) 269 SCM_LOG(1, "Request timeout"); 270 else { 271 SCM_LOG(1, "Request error"); 272 SCM_LOG_HEX(1, &aob->response, sizeof(aob->response)); 273 } 274 if (scmrq->retries) 275 SCM_LOG(1, "Retry request"); 276 else 277 pr_err("An I/O operation to SCM failed with rc=%d\n", 278 scmrq->error); 279 } 280 281 void scm_blk_irq(struct scm_device *scmdev, void *data, int error) 282 { 283 struct scm_request *scmrq = data; 284 struct scm_blk_dev *bdev = scmrq->bdev; 285 286 scmrq->error = error; 287 if (error) 288 __scmrq_log_error(scmrq); 289 290 spin_lock(&bdev->lock); 291 list_add_tail(&scmrq->list, &bdev->finished_requests); 292 spin_unlock(&bdev->lock); 293 tasklet_hi_schedule(&bdev->tasklet); 294 } 295 296 static void scm_blk_handle_error(struct scm_request *scmrq) 297 { 298 struct scm_blk_dev *bdev = scmrq->bdev; 299 unsigned long flags; 300 301 if (scmrq->error != -EIO) 302 goto restart; 303 304 /* For -EIO the response block is valid. */ 305 switch (scmrq->aob->response.eqc) { 306 case EQC_WR_PROHIBIT: 307 spin_lock_irqsave(&bdev->lock, flags); 308 if (bdev->state != SCM_WR_PROHIBIT) 309 pr_info("%lx: Write access to the SCM increment is suspended\n", 310 (unsigned long) bdev->scmdev->address); 311 bdev->state = SCM_WR_PROHIBIT; 312 spin_unlock_irqrestore(&bdev->lock, flags); 313 goto requeue; 314 default: 315 break; 316 } 317 318 restart: 319 if (!scm_start_aob(scmrq->aob)) 320 return; 321 322 requeue: 323 spin_lock_irqsave(&bdev->rq_lock, flags); 324 scm_request_requeue(scmrq); 325 spin_unlock_irqrestore(&bdev->rq_lock, flags); 326 } 327 328 static void scm_blk_tasklet(struct scm_blk_dev *bdev) 329 { 330 struct scm_request *scmrq; 331 unsigned long flags; 332 333 spin_lock_irqsave(&bdev->lock, flags); 334 while (!list_empty(&bdev->finished_requests)) { 335 scmrq = list_first_entry(&bdev->finished_requests, 336 struct scm_request, list); 337 list_del(&scmrq->list); 338 spin_unlock_irqrestore(&bdev->lock, flags); 339 340 if (scmrq->error && scmrq->retries-- > 0) { 341 scm_blk_handle_error(scmrq); 342 343 /* Request restarted or requeued, handle next. */ 344 spin_lock_irqsave(&bdev->lock, flags); 345 continue; 346 } 347 348 if (scm_test_cluster_request(scmrq)) { 349 scm_cluster_request_irq(scmrq); 350 spin_lock_irqsave(&bdev->lock, flags); 351 continue; 352 } 353 354 scm_request_finish(scmrq); 355 spin_lock_irqsave(&bdev->lock, flags); 356 } 357 spin_unlock_irqrestore(&bdev->lock, flags); 358 /* Look out for more requests. */ 359 blk_run_queue(bdev->rq); 360 } 361 362 int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev) 363 { 364 struct request_queue *rq; 365 int len, ret = -ENOMEM; 366 unsigned int devindex, nr_max_blk; 367 368 devindex = atomic_inc_return(&nr_devices) - 1; 369 /* scma..scmz + scmaa..scmzz */ 370 if (devindex > 701) { 371 ret = -ENODEV; 372 goto out; 373 } 374 375 bdev->scmdev = scmdev; 376 bdev->state = SCM_OPER; 377 spin_lock_init(&bdev->rq_lock); 378 spin_lock_init(&bdev->lock); 379 INIT_LIST_HEAD(&bdev->finished_requests); 380 atomic_set(&bdev->queued_reqs, 0); 381 tasklet_init(&bdev->tasklet, 382 (void (*)(unsigned long)) scm_blk_tasklet, 383 (unsigned long) bdev); 384 385 rq = blk_init_queue(scm_blk_request, &bdev->rq_lock); 386 if (!rq) 387 goto out; 388 389 bdev->rq = rq; 390 nr_max_blk = min(scmdev->nr_max_block, 391 (unsigned int) (PAGE_SIZE / sizeof(struct aidaw))); 392 393 blk_queue_logical_block_size(rq, 1 << 12); 394 blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */ 395 blk_queue_max_segments(rq, nr_max_blk); 396 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rq); 397 scm_blk_dev_cluster_setup(bdev); 398 399 bdev->gendisk = alloc_disk(SCM_NR_PARTS); 400 if (!bdev->gendisk) 401 goto out_queue; 402 403 rq->queuedata = scmdev; 404 bdev->gendisk->driverfs_dev = &scmdev->dev; 405 bdev->gendisk->private_data = scmdev; 406 bdev->gendisk->fops = &scm_blk_devops; 407 bdev->gendisk->queue = rq; 408 bdev->gendisk->major = scm_major; 409 bdev->gendisk->first_minor = devindex * SCM_NR_PARTS; 410 411 len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm"); 412 if (devindex > 25) { 413 len += snprintf(bdev->gendisk->disk_name + len, 414 DISK_NAME_LEN - len, "%c", 415 'a' + (devindex / 26) - 1); 416 devindex = devindex % 26; 417 } 418 snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c", 419 'a' + devindex); 420 421 /* 512 byte sectors */ 422 set_capacity(bdev->gendisk, scmdev->size >> 9); 423 add_disk(bdev->gendisk); 424 return 0; 425 426 out_queue: 427 blk_cleanup_queue(rq); 428 out: 429 atomic_dec(&nr_devices); 430 return ret; 431 } 432 433 void scm_blk_dev_cleanup(struct scm_blk_dev *bdev) 434 { 435 tasklet_kill(&bdev->tasklet); 436 del_gendisk(bdev->gendisk); 437 blk_cleanup_queue(bdev->gendisk->queue); 438 put_disk(bdev->gendisk); 439 } 440 441 void scm_blk_set_available(struct scm_blk_dev *bdev) 442 { 443 unsigned long flags; 444 445 spin_lock_irqsave(&bdev->lock, flags); 446 if (bdev->state == SCM_WR_PROHIBIT) 447 pr_info("%lx: Write access to the SCM increment is restored\n", 448 (unsigned long) bdev->scmdev->address); 449 bdev->state = SCM_OPER; 450 spin_unlock_irqrestore(&bdev->lock, flags); 451 } 452 453 static int __init scm_blk_init(void) 454 { 455 int ret = -EINVAL; 456 457 if (!scm_cluster_size_valid()) 458 goto out; 459 460 ret = register_blkdev(0, "scm"); 461 if (ret < 0) 462 goto out; 463 464 scm_major = ret; 465 ret = scm_alloc_rqs(nr_requests); 466 if (ret) 467 goto out_free; 468 469 scm_debug = debug_register("scm_log", 16, 1, 16); 470 if (!scm_debug) { 471 ret = -ENOMEM; 472 goto out_free; 473 } 474 475 debug_register_view(scm_debug, &debug_hex_ascii_view); 476 debug_set_level(scm_debug, 2); 477 478 ret = scm_drv_init(); 479 if (ret) 480 goto out_dbf; 481 482 return ret; 483 484 out_dbf: 485 debug_unregister(scm_debug); 486 out_free: 487 scm_free_rqs(); 488 unregister_blkdev(scm_major, "scm"); 489 out: 490 return ret; 491 } 492 module_init(scm_blk_init); 493 494 static void __exit scm_blk_cleanup(void) 495 { 496 scm_drv_cleanup(); 497 debug_unregister(scm_debug); 498 scm_free_rqs(); 499 unregister_blkdev(scm_major, "scm"); 500 } 501 module_exit(scm_blk_cleanup); 502