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 blk_start_request(req); 228 blk_dump_rq_flags(req, KMSG_COMPONENT " bad request"); 229 blk_end_request_all(req, -EIO); 230 continue; 231 } 232 233 if (!scm_permit_request(bdev, req)) { 234 scm_ensure_queue_restart(bdev); 235 return; 236 } 237 scmrq = scm_request_fetch(); 238 if (!scmrq) { 239 SCM_LOG(5, "no request"); 240 scm_ensure_queue_restart(bdev); 241 return; 242 } 243 scm_request_init(bdev, scmrq, req); 244 if (!scm_reserve_cluster(scmrq)) { 245 SCM_LOG(5, "cluster busy"); 246 scm_request_done(scmrq); 247 return; 248 } 249 if (scm_need_cluster_request(scmrq)) { 250 atomic_inc(&bdev->queued_reqs); 251 blk_start_request(req); 252 scm_initiate_cluster_request(scmrq); 253 return; 254 } 255 scm_request_prepare(scmrq); 256 atomic_inc(&bdev->queued_reqs); 257 blk_start_request(req); 258 259 ret = scm_start_aob(scmrq->aob); 260 if (ret) { 261 SCM_LOG(5, "no subchannel"); 262 scm_request_requeue(scmrq); 263 return; 264 } 265 } 266 } 267 268 static void __scmrq_log_error(struct scm_request *scmrq) 269 { 270 struct aob *aob = scmrq->aob; 271 272 if (scmrq->error == -ETIMEDOUT) 273 SCM_LOG(1, "Request timeout"); 274 else { 275 SCM_LOG(1, "Request error"); 276 SCM_LOG_HEX(1, &aob->response, sizeof(aob->response)); 277 } 278 if (scmrq->retries) 279 SCM_LOG(1, "Retry request"); 280 else 281 pr_err("An I/O operation to SCM failed with rc=%d\n", 282 scmrq->error); 283 } 284 285 void scm_blk_irq(struct scm_device *scmdev, void *data, int error) 286 { 287 struct scm_request *scmrq = data; 288 struct scm_blk_dev *bdev = scmrq->bdev; 289 290 scmrq->error = error; 291 if (error) 292 __scmrq_log_error(scmrq); 293 294 spin_lock(&bdev->lock); 295 list_add_tail(&scmrq->list, &bdev->finished_requests); 296 spin_unlock(&bdev->lock); 297 tasklet_hi_schedule(&bdev->tasklet); 298 } 299 300 static void scm_blk_handle_error(struct scm_request *scmrq) 301 { 302 struct scm_blk_dev *bdev = scmrq->bdev; 303 unsigned long flags; 304 305 if (scmrq->error != -EIO) 306 goto restart; 307 308 /* For -EIO the response block is valid. */ 309 switch (scmrq->aob->response.eqc) { 310 case EQC_WR_PROHIBIT: 311 spin_lock_irqsave(&bdev->lock, flags); 312 if (bdev->state != SCM_WR_PROHIBIT) 313 pr_info("%lx: Write access to the SCM increment is suspended\n", 314 (unsigned long) bdev->scmdev->address); 315 bdev->state = SCM_WR_PROHIBIT; 316 spin_unlock_irqrestore(&bdev->lock, flags); 317 goto requeue; 318 default: 319 break; 320 } 321 322 restart: 323 if (!scm_start_aob(scmrq->aob)) 324 return; 325 326 requeue: 327 spin_lock_irqsave(&bdev->rq_lock, flags); 328 scm_request_requeue(scmrq); 329 spin_unlock_irqrestore(&bdev->rq_lock, flags); 330 } 331 332 static void scm_blk_tasklet(struct scm_blk_dev *bdev) 333 { 334 struct scm_request *scmrq; 335 unsigned long flags; 336 337 spin_lock_irqsave(&bdev->lock, flags); 338 while (!list_empty(&bdev->finished_requests)) { 339 scmrq = list_first_entry(&bdev->finished_requests, 340 struct scm_request, list); 341 list_del(&scmrq->list); 342 spin_unlock_irqrestore(&bdev->lock, flags); 343 344 if (scmrq->error && scmrq->retries-- > 0) { 345 scm_blk_handle_error(scmrq); 346 347 /* Request restarted or requeued, handle next. */ 348 spin_lock_irqsave(&bdev->lock, flags); 349 continue; 350 } 351 352 if (scm_test_cluster_request(scmrq)) { 353 scm_cluster_request_irq(scmrq); 354 spin_lock_irqsave(&bdev->lock, flags); 355 continue; 356 } 357 358 scm_request_finish(scmrq); 359 spin_lock_irqsave(&bdev->lock, flags); 360 } 361 spin_unlock_irqrestore(&bdev->lock, flags); 362 /* Look out for more requests. */ 363 blk_run_queue(bdev->rq); 364 } 365 366 int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev) 367 { 368 struct request_queue *rq; 369 int len, ret = -ENOMEM; 370 unsigned int devindex, nr_max_blk; 371 372 devindex = atomic_inc_return(&nr_devices) - 1; 373 /* scma..scmz + scmaa..scmzz */ 374 if (devindex > 701) { 375 ret = -ENODEV; 376 goto out; 377 } 378 379 bdev->scmdev = scmdev; 380 bdev->state = SCM_OPER; 381 spin_lock_init(&bdev->rq_lock); 382 spin_lock_init(&bdev->lock); 383 INIT_LIST_HEAD(&bdev->finished_requests); 384 atomic_set(&bdev->queued_reqs, 0); 385 tasklet_init(&bdev->tasklet, 386 (void (*)(unsigned long)) scm_blk_tasklet, 387 (unsigned long) bdev); 388 389 rq = blk_init_queue(scm_blk_request, &bdev->rq_lock); 390 if (!rq) 391 goto out; 392 393 bdev->rq = rq; 394 nr_max_blk = min(scmdev->nr_max_block, 395 (unsigned int) (PAGE_SIZE / sizeof(struct aidaw))); 396 397 blk_queue_logical_block_size(rq, 1 << 12); 398 blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */ 399 blk_queue_max_segments(rq, nr_max_blk); 400 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rq); 401 scm_blk_dev_cluster_setup(bdev); 402 403 bdev->gendisk = alloc_disk(SCM_NR_PARTS); 404 if (!bdev->gendisk) 405 goto out_queue; 406 407 rq->queuedata = scmdev; 408 bdev->gendisk->driverfs_dev = &scmdev->dev; 409 bdev->gendisk->private_data = scmdev; 410 bdev->gendisk->fops = &scm_blk_devops; 411 bdev->gendisk->queue = rq; 412 bdev->gendisk->major = scm_major; 413 bdev->gendisk->first_minor = devindex * SCM_NR_PARTS; 414 415 len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm"); 416 if (devindex > 25) { 417 len += snprintf(bdev->gendisk->disk_name + len, 418 DISK_NAME_LEN - len, "%c", 419 'a' + (devindex / 26) - 1); 420 devindex = devindex % 26; 421 } 422 snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c", 423 'a' + devindex); 424 425 /* 512 byte sectors */ 426 set_capacity(bdev->gendisk, scmdev->size >> 9); 427 add_disk(bdev->gendisk); 428 return 0; 429 430 out_queue: 431 blk_cleanup_queue(rq); 432 out: 433 atomic_dec(&nr_devices); 434 return ret; 435 } 436 437 void scm_blk_dev_cleanup(struct scm_blk_dev *bdev) 438 { 439 tasklet_kill(&bdev->tasklet); 440 del_gendisk(bdev->gendisk); 441 blk_cleanup_queue(bdev->gendisk->queue); 442 put_disk(bdev->gendisk); 443 } 444 445 void scm_blk_set_available(struct scm_blk_dev *bdev) 446 { 447 unsigned long flags; 448 449 spin_lock_irqsave(&bdev->lock, flags); 450 if (bdev->state == SCM_WR_PROHIBIT) 451 pr_info("%lx: Write access to the SCM increment is restored\n", 452 (unsigned long) bdev->scmdev->address); 453 bdev->state = SCM_OPER; 454 spin_unlock_irqrestore(&bdev->lock, flags); 455 } 456 457 static int __init scm_blk_init(void) 458 { 459 int ret = -EINVAL; 460 461 if (!scm_cluster_size_valid()) 462 goto out; 463 464 ret = register_blkdev(0, "scm"); 465 if (ret < 0) 466 goto out; 467 468 scm_major = ret; 469 ret = scm_alloc_rqs(nr_requests); 470 if (ret) 471 goto out_free; 472 473 scm_debug = debug_register("scm_log", 16, 1, 16); 474 if (!scm_debug) { 475 ret = -ENOMEM; 476 goto out_free; 477 } 478 479 debug_register_view(scm_debug, &debug_hex_ascii_view); 480 debug_set_level(scm_debug, 2); 481 482 ret = scm_drv_init(); 483 if (ret) 484 goto out_dbf; 485 486 return ret; 487 488 out_dbf: 489 debug_unregister(scm_debug); 490 out_free: 491 scm_free_rqs(); 492 unregister_blkdev(scm_major, "scm"); 493 out: 494 return ret; 495 } 496 module_init(scm_blk_init); 497 498 static void __exit scm_blk_cleanup(void) 499 { 500 scm_drv_cleanup(); 501 debug_unregister(scm_debug); 502 scm_free_rqs(); 503 unregister_blkdev(scm_major, "scm"); 504 } 505 module_exit(scm_blk_cleanup); 506