drivers/s390/char/sclp.c

   1 /*
   2  *  drivers/s390/char/sclp.c
   3  *     core function to access sclp interface
   4  *
   5  *  S390 version
   6  *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
   7  *    Author(s): Martin Peschke <mpeschke@de.ibm.com>
   8  *               Martin Schwidefsky <schwidefsky@de.ibm.com>
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/module.h>
  13 #include <linux/kmod.h>
  14 #include <linux/bootmem.h>
  15 #include <linux/err.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/slab.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/timer.h>
  21 #include <linux/init.h>
  22 #include <linux/cpumask.h>
  23 #include <linux/reboot.h>
  24 #include <asm/s390_ext.h>
  25 #include <asm/processor.h>
  26
  27 #include "sclp.h"
  28
  29 #define SCLP_CORE_PRINT_HEADER "sclp low level driver: "
  30
  31 /* Structure for register_early_external_interrupt. */
  32 static ext_int_info_t ext_int_info_hwc;
  33
  34 /* spinlock to protect global variables of sclp_core */
  35 static spinlock_t sclp_lock;
  36
  37 /* Mask of valid sclp events */
  38 static sccb_mask_t sclp_receive_mask;
  39 static sccb_mask_t sclp_send_mask;
  40
  41 /* List of registered event types */
  42 static struct list_head sclp_reg_list;
  43
  44 /* sccb queue */
  45 static struct list_head sclp_req_queue;
  46
  47 /* sccb for unconditional read */
  48 static struct sclp_req sclp_read_req;
  49 static char sclp_read_sccb[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
  50 /* sccb for write mask sccb */
  51 static char sclp_init_sccb[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
  52
  53 /* Timer for init mask retries. */
  54 static struct timer_list retry_timer;
  55
  56 /* Timer for busy retries. */
  57 static struct timer_list sclp_busy_timer;
  58
  59 static volatile unsigned long sclp_status = 0;
  60 /* some status flags */
  61 #define SCLP_INIT               0
  62 #define SCLP_RUNNING            1
  63 #define SCLP_READING            2
  64 #define SCLP_SHUTDOWN           3
  65
  66 #define SCLP_INIT_POLL_INTERVAL 1
  67 #define SCLP_BUSY_POLL_INTERVAL 1
  68
  69 #define SCLP_COMMAND_INITIATED  0
  70 #define SCLP_BUSY               2
  71 #define SCLP_NOT_OPERATIONAL    3
  72
  73 /*
  74  * assembler instruction for Service Call
  75  */
  76 static int
  77 __service_call(sclp_cmdw_t command, void *sccb)
  78 {
  79         int cc;
  80
  81         /*
  82          *  Mnemonic:   SERVC   Rx, Ry  [RRE]
  83          *
  84          *  Rx: SCLP command word
  85          *  Ry: address of SCCB
  86          */
  87         __asm__ __volatile__(
  88                 "   .insn rre,0xb2200000,%1,%2\n"  /* servc %1,%2 */
  89                 "   ipm   %0\n"
  90                 "   srl   %0,28"
  91                 : "=&d" (cc)
  92                 : "d" (command), "a" (__pa(sccb))
  93                 : "cc", "memory" );
  94         /*
  95          * cc == 0:   Service Call succesful initiated
  96          * cc == 2:   SCLP busy, new Service Call not initiated,
  97          *            new SCCB unchanged
  98          * cc == 3:   SCLP function not operational
  99          */
 100         if (cc == SCLP_NOT_OPERATIONAL)
 101                 return -EIO;
 102         if (cc == SCLP_BUSY)
 103                 return -EBUSY;
 104         return 0;
 105 }
 106
 107 static void
 108 sclp_start_request(void)
 109 {
 110         struct sclp_req *req;
 111         int rc;
 112         unsigned long flags;
 113
 114         spin_lock_irqsave(&sclp_lock, flags);
 115         /* quick exit if sclp is already in use */
 116         if (test_bit(SCLP_RUNNING, &sclp_status)) {
 117                 spin_unlock_irqrestore(&sclp_lock, flags);
 118                 return;
 119         }
 120         /* Try to start requests from the request queue. */
 121         while (!list_empty(&sclp_req_queue)) {
 122                 req = list_entry(sclp_req_queue.next, struct sclp_req, list);
 123                 rc = __service_call(req->command, req->sccb);
 124                 if (rc == 0) {
 125                         /* Sucessfully started request. */
 126                         req->status = SCLP_REQ_RUNNING;
 127                         /* Request active. Set running indication. */
 128                         set_bit(SCLP_RUNNING, &sclp_status);
 129                         break;
 130                 }
 131                 if (rc == -EBUSY) {
 132                         /**
 133                          * SCLP is busy but no request is running.
 134                          * Try again later.
 135                          */
 136                         if (!timer_pending(&sclp_busy_timer) ||
 137                             !mod_timer(&sclp_busy_timer,
 138                                        jiffies + SCLP_BUSY_POLL_INTERVAL*HZ)) {
 139                                 sclp_busy_timer.function =
 140                                         (void *) sclp_start_request;
 141                                 sclp_busy_timer.expires =
 142                                         jiffies + SCLP_BUSY_POLL_INTERVAL*HZ;
 143                                 add_timer(&sclp_busy_timer);
 144                         }
 145                         break;
 146                 }
 147                 /* Request failed. */
 148                 req->status = SCLP_REQ_FAILED;
 149                 list_del(&req->list);
 150                 if (req->callback) {
 151                         spin_unlock_irqrestore(&sclp_lock, flags);
 152                         req->callback(req, req->callback_data);
 153                         spin_lock_irqsave(&sclp_lock, flags);
 154                 }
 155         }
 156         spin_unlock_irqrestore(&sclp_lock, flags);
 157 }
 158
 159 static int
 160 sclp_process_evbufs(struct sccb_header *sccb)
 161 {
 162         int result;
 163         unsigned long flags;
 164         struct evbuf_header *evbuf;
 165         struct list_head *l;
 166         struct sclp_register *t;
 167
 168         spin_lock_irqsave(&sclp_lock, flags);
 169         evbuf = (struct evbuf_header *) (sccb + 1);
 170         result = 0;
 171         while ((addr_t) evbuf < (addr_t) sccb + sccb->length) {
 172                 /* check registered event */
 173                 t = NULL;
 174                 list_for_each(l, &sclp_reg_list) {
 175                         t = list_entry(l, struct sclp_register, list);
 176                         if (t->receive_mask & (1 << (32 - evbuf->type))) {
 177                                 if (t->receiver_fn != NULL) {
 178                                         spin_unlock_irqrestore(&sclp_lock,
 179                                                                flags);
 180                                         t->receiver_fn(evbuf);
 181                                         spin_lock_irqsave(&sclp_lock, flags);
 182                                 }
 183                                 break;
 184                         }
 185                         else
 186                                 t = NULL;
 187                 }
 188                 /* Check for unrequested event buffer */
 189                 if (t == NULL)
 190                         result = -ENOSYS;
 191                 evbuf = (struct evbuf_header *)
 192                                 ((addr_t) evbuf + evbuf->length);
 193         }
 194         spin_unlock_irqrestore(&sclp_lock, flags);
 195         return result;
 196 }
 197
 198 char *
 199 sclp_error_message(u16 rc)
 200 {
 201         static struct {
 202                 u16 code; char *msg;
 203         } sclp_errors[] = {
 204                 { 0x0000, "No response code stored (machine malfunction)" },
 205                 { 0x0020, "Normal Completion" },
 206                 { 0x0040, "SCLP equipment check" },
 207                 { 0x0100, "SCCB boundary violation" },
 208                 { 0x01f0, "Invalid command" },
 209                 { 0x0220, "Normal Completion; suppressed buffers pending" },
 210                 { 0x0300, "Insufficient SCCB length" },
 211                 { 0x0340, "Contained SCLP equipment check" },
 212                 { 0x05f0, "Target resource in improper state" },
 213                 { 0x40f0, "Invalid function code/not installed" },
 214                 { 0x60f0, "No buffers stored" },
 215                 { 0x62f0, "No buffers stored; suppressed buffers pending" },
 216                 { 0x70f0, "Invalid selection mask" },
 217                 { 0x71f0, "Event buffer exceeds available space" },
 218                 { 0x72f0, "Inconsistent lengths" },
 219                 { 0x73f0, "Event buffer syntax error" }
 220         };
 221         int i;
 222         for (i = 0; i < sizeof(sclp_errors)/sizeof(sclp_errors[0]); i++)
 223                 if (rc == sclp_errors[i].code)
 224                         return sclp_errors[i].msg;
 225         return "Invalid response code";
 226 }
 227
 228 /*
 229  * postprocessing of unconditional read service call
 230  */
 231 static void
 232 sclp_unconditional_read_cb(struct sclp_req *read_req, void *data)
 233 {
 234         struct sccb_header *sccb;
 235
 236         sccb = read_req->sccb;
 237         if (sccb->response_code == 0x0020 ||
 238             sccb->response_code == 0x0220) {
 239                 if (sclp_process_evbufs(sccb) != 0)
 240                         printk(KERN_WARNING SCLP_CORE_PRINT_HEADER
 241                                "unconditional read: "
 242                                "unrequested event buffer received.\n");
 243         }
 244
 245         if (sccb->response_code != 0x0020)
 246                 printk(KERN_WARNING SCLP_CORE_PRINT_HEADER
 247                        "unconditional read: %s (response code=0x%x).\n",
 248                        sclp_error_message(sccb->response_code),
 249                        sccb->response_code);
 250
 251         clear_bit(SCLP_READING, &sclp_status);
 252 }
 253
 254 /*
 255  * Function to queue Read Event Data/Unconditional Read
 256  */
 257 static void
 258 __sclp_unconditional_read(void)
 259 {
 260         struct sccb_header *sccb;
 261         struct sclp_req *read_req;
 262
 263         /*
 264          * Don't try to initiate Unconditional Read if we are not able to
 265          * receive anything
 266          */
 267         if (sclp_receive_mask == 0)
 268                 return;
 269         /* Don't try reading if a read is already outstanding */
 270         if (test_and_set_bit(SCLP_READING, &sclp_status))
 271                 return;
 272         /* Initialize read sccb */
 273         sccb = (struct sccb_header *) sclp_read_sccb;
 274         clear_page(sccb);
 275         sccb->length = PAGE_SIZE;
 276         sccb->function_code = 0;        /* unconditional read */
 277         sccb->control_mask[2] = 0x80;   /* variable length response */
 278         /* Initialize request structure */
 279         read_req = &sclp_read_req;
 280         read_req->command = SCLP_CMDW_READDATA;
 281         read_req->status = SCLP_REQ_QUEUED;
 282         read_req->callback = sclp_unconditional_read_cb;
 283         read_req->sccb = sccb;
 284         /* Add read request to the head of queue */
 285         list_add(&read_req->list, &sclp_req_queue);
 286 }
 287
 288 /* Bit masks to interpret external interruption parameter contents. */
 289 #define EXT_INT_SCCB_MASK               0xfffffff8
 290 #define EXT_INT_STATECHANGE_PENDING     0x00000002
 291 #define EXT_INT_EVBUF_PENDING           0x00000001
 292
 293 /*
 294  * Handler for service-signal external interruptions
 295  */
 296 static void
 297 sclp_interrupt_handler(struct pt_regs *regs, __u16 code)
 298 {
 299         u32 ext_int_param, finished_sccb, evbuf_pending;
 300         struct list_head *l;
 301         struct sclp_req *req, *tmp;
 302
 303         spin_lock(&sclp_lock);
 304         /*
 305          * Only process interrupt if sclp is initialized.
 306          * This avoids strange effects for a pending request
 307          * from before the last re-ipl.
 308          */
 309         if (!test_bit(SCLP_INIT, &sclp_status)) {
 310                 /* Now clear the running bit */
 311                 clear_bit(SCLP_RUNNING, &sclp_status);
 312                 spin_unlock(&sclp_lock);
 313                 return;
 314         }
 315         ext_int_param = S390_lowcore.ext_params;
 316         finished_sccb = ext_int_param & EXT_INT_SCCB_MASK;
 317         evbuf_pending = ext_int_param & (EXT_INT_EVBUF_PENDING |
 318                                          EXT_INT_STATECHANGE_PENDING);
 319         req = NULL;
 320         if (finished_sccb != 0U) {
 321                 list_for_each(l, &sclp_req_queue) {
 322                         tmp = list_entry(l, struct sclp_req, list);
 323                         if (finished_sccb == (u32)(addr_t) tmp->sccb) {
 324                                 list_del(&tmp->list);
 325                                 req = tmp;
 326                                 break;
 327                         }
 328                 }
 329         }
 330         spin_unlock(&sclp_lock);
 331         /* Perform callback */
 332         if (req != NULL) {
 333                 req->status = SCLP_REQ_DONE;
 334                 if (req->callback != NULL)
 335                         req->callback(req, req->callback_data);
 336         }
 337         spin_lock(&sclp_lock);
 338         /* Head queue a read sccb if an event buffer is pending */
 339         if (evbuf_pending)
 340                 __sclp_unconditional_read();
 341         /* Now clear the running bit if SCLP indicated a finished SCCB */
 342         if (finished_sccb != 0U)
 343                 clear_bit(SCLP_RUNNING, &sclp_status);
 344         spin_unlock(&sclp_lock);
 345         /* and start next request on the queue */
 346         sclp_start_request();
 347 }
 348
 349 /*
 350  * Wait synchronously for external interrupt of sclp. We may not receive
 351  * any other external interrupt, so we disable all other external interrupts
 352  * in control register 0.
 353  */
 354 void
 355 sclp_sync_wait(void)
 356 {
 357         unsigned long psw_mask;
 358         unsigned long cr0, cr0_sync;
 359
 360         /* Prevent BH from executing. */
 361         local_bh_disable();
 362         /*
 363          * save cr0
 364          * enable service signal external interruption (cr0.22)
 365          * disable cr0.20-21, cr0.25, cr0.27, cr0.30-31
 366          * don't touch any other bit in cr0
 367          */
 368         __ctl_store(cr0, 0, 0);
 369         cr0_sync = cr0;
 370         cr0_sync |= 0x00000200;
 371         cr0_sync &= 0xFFFFF3AC;
 372         __ctl_load(cr0_sync, 0, 0);
 373
 374         /* enable external interruptions (PSW-mask.7) */
 375         asm volatile ("STOSM 0(%1),0x01"
 376                       : "=m" (psw_mask) : "a" (&psw_mask) : "memory");
 377
 378         /* wait until ISR signals receipt of interrupt */
 379         while (test_bit(SCLP_RUNNING, &sclp_status)) {
 380                 barrier();
 381                 cpu_relax();
 382         }
 383
 384         /* disable external interruptions */
 385         asm volatile ("SSM 0(%0)"
 386                       : : "a" (&psw_mask) : "memory");
 387
 388         /* restore cr0 */
 389         __ctl_load(cr0, 0, 0);
 390         __local_bh_enable();
 391 }
 392
 393 /*
 394  * Queue an SCLP request. Request will immediately be processed if queue is
 395  * empty.
 396  */
 397 void
 398 sclp_add_request(struct sclp_req *req)
 399 {
 400         unsigned long flags;
 401
 402         if (!test_bit(SCLP_INIT, &sclp_status)) {
 403                 req->status = SCLP_REQ_FAILED;
 404                 if (req->callback != NULL)
 405                         req->callback(req, req->callback_data);
 406                 return;
 407         }
 408         spin_lock_irqsave(&sclp_lock, flags);
 409         /* queue the request */
 410         req->status = SCLP_REQ_QUEUED;
 411         list_add_tail(&req->list, &sclp_req_queue);
 412         spin_unlock_irqrestore(&sclp_lock, flags);
 413         /* try to start the first request on the queue */
 414         sclp_start_request();
 415 }
 416
 417 /* state change notification */
 418 struct sclp_statechangebuf {
 419         struct evbuf_header     header;
 420         u8              validity_sclp_active_facility_mask : 1;
 421         u8              validity_sclp_receive_mask : 1;
 422         u8              validity_sclp_send_mask : 1;
 423         u8              validity_read_data_function_mask : 1;
 424         u16             _zeros : 12;
 425         u16             mask_length;
 426         u64             sclp_active_facility_mask;
 427         sccb_mask_t     sclp_receive_mask;
 428         sccb_mask_t     sclp_send_mask;
 429         u32             read_data_function_mask;
 430 } __attribute__((packed));
 431
 432 static inline void
 433 __sclp_notify_state_change(void)
 434 {
 435         struct list_head *l;
 436         struct sclp_register *t;
 437         sccb_mask_t receive_mask, send_mask;
 438
 439         list_for_each(l, &sclp_reg_list) {
 440                 t = list_entry(l, struct sclp_register, list);
 441                 receive_mask = t->receive_mask & sclp_receive_mask;
 442                 send_mask = t->send_mask & sclp_send_mask;
 443                 if (t->sclp_receive_mask != receive_mask ||
 444                     t->sclp_send_mask != send_mask) {
 445                         t->sclp_receive_mask = receive_mask;
 446                         t->sclp_send_mask = send_mask;
 447                         if (t->state_change_fn != NULL)
 448                                 t->state_change_fn(t);
 449                 }
 450         }
 451 }
 452
 453 static void
 454 sclp_state_change(struct evbuf_header *evbuf)
 455 {
 456         unsigned long flags;
 457         struct sclp_statechangebuf *scbuf;
 458
 459         spin_lock_irqsave(&sclp_lock, flags);
 460         scbuf = (struct sclp_statechangebuf *) evbuf;
 461
 462         if (scbuf->validity_sclp_receive_mask) {
 463                 if (scbuf->mask_length != sizeof(sccb_mask_t))
 464                         printk(KERN_WARNING SCLP_CORE_PRINT_HEADER
 465                                "state change event with mask length %i\n",
 466                                scbuf->mask_length);
 467                 else
 468                         /* set new receive mask */
 469                         sclp_receive_mask = scbuf->sclp_receive_mask;
 470         }
 471
 472         if (scbuf->validity_sclp_send_mask) {
 473                 if (scbuf->mask_length != sizeof(sccb_mask_t))
 474                         printk(KERN_WARNING SCLP_CORE_PRINT_HEADER
 475                                "state change event with mask length %i\n",
 476                                scbuf->mask_length);
 477                 else
 478                         /* set new send mask */
 479                         sclp_send_mask = scbuf->sclp_send_mask;
 480         }
 481
 482         __sclp_notify_state_change();
 483         spin_unlock_irqrestore(&sclp_lock, flags);
 484 }
 485
 486 static struct sclp_register sclp_state_change_event = {
 487         .receive_mask = EvTyp_StateChange_Mask,
 488         .receiver_fn = sclp_state_change
 489 };
 490
 491
 492 /*
 493  * SCLP quiesce event handler
 494  */
 495 #ifdef CONFIG_SMP
 496 static void
 497 do_load_quiesce_psw(void * __unused)
 498 {
 499         static atomic_t cpuid = ATOMIC_INIT(-1);
 500         psw_t quiesce_psw;
 501         __u32 status;
 502         int i;
 503
 504         if (atomic_compare_and_swap(-1, smp_processor_id(), &cpuid))
 505                 signal_processor(smp_processor_id(), sigp_stop);
 506         /* Wait for all other cpus to enter stopped state */
 507         i = 1;
 508         while (i < NR_CPUS) {
 509                 if (!cpu_online(i)) {
 510                         i++;
 511                         continue;
 512                 }
 513                 switch (signal_processor_ps(&status, 0, i, sigp_sense)) {
 514                 case sigp_order_code_accepted:
 515                 case sigp_status_stored:
 516                         /* Check for stopped and check stop state */
 517                         if (status & 0x50)
 518                                 i++;
 519                         break;
 520                 case sigp_busy:
 521                         break;
 522                 case sigp_not_operational:
 523                         i++;
 524                         break;
 525                 }
 526         }
 527         /* Quiesce the last cpu with the special psw */
 528         quiesce_psw.mask = PSW_BASE_BITS | PSW_MASK_WAIT;
 529         quiesce_psw.addr = 0xfff;
 530         __load_psw(quiesce_psw);
 531 }
 532
 533 static void
 534 do_machine_quiesce(void)
 535 {
 536         on_each_cpu(do_load_quiesce_psw, NULL, 0, 0);
 537 }
 538 #else
 539 static void
 540 do_machine_quiesce(void)
 541 {
 542         psw_t quiesce_psw;
 543
 544         quiesce_psw.mask = PSW_BASE_BITS | PSW_MASK_WAIT;
 545         quiesce_psw.addr = 0xfff;
 546         __load_psw(quiesce_psw);
 547 }
 548 #endif
 549
 550 extern void ctrl_alt_del(void);
 551
 552 static void
 553 sclp_quiesce(struct evbuf_header *evbuf)
 554 {
 555         /*
 556          * We got a "shutdown" request.
 557          * Add a call to an appropriate "shutdown" routine here. This
 558          * routine should set all PSWs to 'disabled-wait', 'stopped'
 559          * or 'check-stopped' - except 1 PSW which needs to carry a
 560          * special bit pattern called 'quiesce PSW'.
 561          */
 562         _machine_restart = (void *) do_machine_quiesce;
 563         _machine_halt = do_machine_quiesce;
 564         _machine_power_off = do_machine_quiesce;
 565         ctrl_alt_del();
 566 }
 567
 568 static struct sclp_register sclp_quiesce_event = {
 569         .receive_mask = EvTyp_SigQuiesce_Mask,
 570         .receiver_fn = sclp_quiesce
 571 };
 572
 573 /* initialisation of SCLP */
 574 struct init_sccb {
 575         struct sccb_header header;
 576         u16 _reserved;
 577         u16 mask_length;
 578         sccb_mask_t receive_mask;
 579         sccb_mask_t send_mask;
 580         sccb_mask_t sclp_send_mask;
 581         sccb_mask_t sclp_receive_mask;
 582 } __attribute__((packed));
 583
 584 static void sclp_init_mask_retry(unsigned long);
 585
 586 static int
 587 sclp_init_mask(void)
 588 {
 589         unsigned long flags;
 590         struct init_sccb *sccb;
 591         struct sclp_req *req;
 592         struct list_head *l;
 593         struct sclp_register *t;
 594         int rc;
 595
 596         sccb = (struct init_sccb *) sclp_init_sccb;
 597         /* stick the request structure to the end of the init sccb page */
 598         req = (struct sclp_req *) ((addr_t) sccb + PAGE_SIZE) - 1;
 599
 600         /* SCLP setup concerning receiving and sending Event Buffers */
 601         req->command = SCLP_CMDW_WRITEMASK;
 602         req->status = SCLP_REQ_QUEUED;
 603         req->callback = NULL;
 604         req->sccb = sccb;
 605         /* setup sccb for writemask command */
 606         memset(sccb, 0, sizeof(struct init_sccb));
 607         sccb->header.length = sizeof(struct init_sccb);
 608         sccb->mask_length = sizeof(sccb_mask_t);
 609         /* copy in the sccb mask of the registered event types */
 610         spin_lock_irqsave(&sclp_lock, flags);
 611         if (!test_bit(SCLP_SHUTDOWN, &sclp_status)) {
 612                 list_for_each(l, &sclp_reg_list) {
 613                         t = list_entry(l, struct sclp_register, list);
 614                         sccb->receive_mask |= t->receive_mask;
 615                         sccb->send_mask |= t->send_mask;
 616                 }
 617         }
 618         sccb->sclp_receive_mask = 0;
 619         sccb->sclp_send_mask = 0;
 620         if (test_bit(SCLP_INIT, &sclp_status)) {
 621                 /* add request to sclp queue */
 622                 list_add_tail(&req->list, &sclp_req_queue);
 623                 spin_unlock_irqrestore(&sclp_lock, flags);
 624                 /* and start if SCLP is idle */
 625                 sclp_start_request();
 626                 /* now wait for completion */
 627                 while (req->status != SCLP_REQ_DONE &&
 628                        req->status != SCLP_REQ_FAILED)
 629                         sclp_sync_wait();
 630                 spin_lock_irqsave(&sclp_lock, flags);
 631         } else {
 632                 /*
 633                  * Special case for the very first write mask command.
 634                  * The interrupt handler is not removing request from
 635                  * the request queue and doesn't call callbacks yet
 636                  * because there might be an pending old interrupt
 637                  * after a Re-IPL. We have to receive and ignore it.
 638                  */
 639                 do {
 640                         rc = __service_call(req->command, req->sccb);
 641                         if (rc == 0)
 642                                 set_bit(SCLP_RUNNING, &sclp_status);
 643                         spin_unlock_irqrestore(&sclp_lock, flags);
 644                         if (rc == -EIO)
 645                                 return -ENOSYS;
 646                         sclp_sync_wait();
 647                         spin_lock_irqsave(&sclp_lock, flags);
 648                 } while (rc == -EBUSY);
 649         }
 650         if (sccb->header.response_code != 0x0020) {
 651                 /* WRITEMASK failed - we cannot rely on receiving a state
 652                    change event, so initially, polling is the only alternative
 653                    for us to ever become operational. */
 654                 if (!test_bit(SCLP_SHUTDOWN, &sclp_status) &&
 655                     (!timer_pending(&retry_timer) ||
 656                      !mod_timer(&retry_timer,
 657                                jiffies + SCLP_INIT_POLL_INTERVAL*HZ))) {
 658                         retry_timer.function = sclp_init_mask_retry;
 659                         retry_timer.data = 0;
 660                         retry_timer.expires = jiffies +
 661                                 SCLP_INIT_POLL_INTERVAL*HZ;
 662                         add_timer(&retry_timer);
 663                 }
 664         } else {
 665                 sclp_receive_mask = sccb->sclp_receive_mask;
 666                 sclp_send_mask = sccb->sclp_send_mask;
 667                 __sclp_notify_state_change();
 668         }
 669         spin_unlock_irqrestore(&sclp_lock, flags);
 670         return 0;
 671 }
 672
 673 static void
 674 sclp_init_mask_retry(unsigned long data)
 675 {
 676         sclp_init_mask();
 677 }
 678
 679 /* Reboot event handler - reset send and receive mask to prevent pending SCLP
 680  * events from interfering with rebooted system. */
 681 static int
 682 sclp_reboot_event(struct notifier_block *this, unsigned long event, void *ptr)
 683 {
 684         unsigned long flags;
 685
 686         /* Note: need spinlock to maintain atomicity when accessing global
 687          * variables. */
 688         spin_lock_irqsave(&sclp_lock, flags);
 689         set_bit(SCLP_SHUTDOWN, &sclp_status);
 690         spin_unlock_irqrestore(&sclp_lock, flags);
 691         sclp_init_mask();
 692         return NOTIFY_DONE;
 693 }
 694
 695 static struct notifier_block sclp_reboot_notifier = {
 696         .notifier_call = sclp_reboot_event
 697 };
 698
 699 /*
 700  * sclp setup function. Called early (no kmalloc!) from sclp_console_init().
 701  */
 702 static int
 703 sclp_init(void)
 704 {
 705         int rc;
 706
 707         if (test_bit(SCLP_INIT, &sclp_status))
 708                 /* Already initialized. */
 709                 return 0;
 710
 711         spin_lock_init(&sclp_lock);
 712         INIT_LIST_HEAD(&sclp_req_queue);
 713
 714         /* init event list */
 715         INIT_LIST_HEAD(&sclp_reg_list);
 716         list_add(&sclp_state_change_event.list, &sclp_reg_list);
 717         list_add(&sclp_quiesce_event.list, &sclp_reg_list);
 718
 719         rc = register_reboot_notifier(&sclp_reboot_notifier);
 720         if (rc)
 721                 return rc;
 722
 723         /*
 724          * request the 0x2401 external interrupt
 725          * The sclp driver is initialized early (before kmalloc works). We
 726          * need to use register_early_external_interrupt.
 727          */
 728         if (register_early_external_interrupt(0x2401, sclp_interrupt_handler,
 729                                               &ext_int_info_hwc) != 0)
 730                 return -EBUSY;
 731
 732         /* enable service-signal external interruptions,
 733          * Control Register 0 bit 22 := 1
 734          * (besides PSW bit 7 must be set to 1 sometimes for external
 735          * interruptions)
 736          */
 737         ctl_set_bit(0, 9);
 738
 739         init_timer(&retry_timer);
 740         init_timer(&sclp_busy_timer);
 741         /* do the initial write event mask */
 742         rc = sclp_init_mask();
 743         if (rc == 0) {
 744                 /* Ok, now everything is setup right. */
 745                 set_bit(SCLP_INIT, &sclp_status);
 746                 return 0;
 747         }
 748
 749         /* The sclp_init_mask failed. SCLP is broken, unregister and exit. */
 750         ctl_clear_bit(0,9);
 751         unregister_early_external_interrupt(0x2401, sclp_interrupt_handler,
 752                                             &ext_int_info_hwc);
 753
 754         return rc;
 755 }
 756
 757 /*
 758  * Register the SCLP event listener identified by REG. Return 0 on success.
 759  * Some error codes and their meaning:
 760  *
 761  *  -ENODEV = SCLP interface is not supported on this machine
 762  *   -EBUSY = there is already a listener registered for the requested
 763  *            event type
 764  *     -EIO = SCLP interface is currently not operational
 765  */
 766 int
 767 sclp_register(struct sclp_register *reg)
 768 {
 769         unsigned long flags;
 770         struct list_head *l;
 771         struct sclp_register *t;
 772
 773         if (!MACHINE_HAS_SCLP)
 774                 return -ENODEV;
 775
 776         if (!test_bit(SCLP_INIT, &sclp_status))
 777                 sclp_init();
 778         spin_lock_irqsave(&sclp_lock, flags);
 779         /* check already registered event masks for collisions */
 780         list_for_each(l, &sclp_reg_list) {
 781                 t = list_entry(l, struct sclp_register, list);
 782                 if (t->receive_mask & reg->receive_mask ||
 783                     t->send_mask & reg->send_mask) {
 784                         spin_unlock_irqrestore(&sclp_lock, flags);
 785                         return -EBUSY;
 786                 }
 787         }
 788         /*
 789          * set present mask to 0 to trigger state change
 790          * callback in sclp_init_mask
 791          */
 792         reg->sclp_receive_mask = 0;
 793         reg->sclp_send_mask = 0;
 794         list_add(&reg->list, &sclp_reg_list);
 795         spin_unlock_irqrestore(&sclp_lock, flags);
 796         sclp_init_mask();
 797         return 0;
 798 }
 799
 800 /*
 801  * Unregister the SCLP event listener identified by REG.
 802  */
 803 void
 804 sclp_unregister(struct sclp_register *reg)
 805 {
 806         unsigned long flags;
 807
 808         spin_lock_irqsave(&sclp_lock, flags);
 809         list_del(&reg->list);
 810         spin_unlock_irqrestore(&sclp_lock, flags);
 811         sclp_init_mask();
 812 }
 813
 814 #define SCLP_EVBUF_PROCESSED    0x80
 815
 816 /*
 817  * Traverse array of event buffers contained in SCCB and remove all buffers
 818  * with a set "processed" flag. Return the number of unprocessed buffers.
 819  */
 820 int
 821 sclp_remove_processed(struct sccb_header *sccb)
 822 {
 823         struct evbuf_header *evbuf;
 824         int unprocessed;
 825         u16 remaining;
 826
 827         evbuf = (struct evbuf_header *) (sccb + 1);
 828         unprocessed = 0;
 829         remaining = sccb->length - sizeof(struct sccb_header);
 830         while (remaining > 0) {
 831                 remaining -= evbuf->length;
 832                 if (evbuf->flags & SCLP_EVBUF_PROCESSED) {
 833                         sccb->length -= evbuf->length;
 834                         memcpy((void *) evbuf,
 835                                (void *) ((addr_t) evbuf + evbuf->length),
 836                                remaining);
 837                 } else {
 838                         unprocessed++;
 839                         evbuf = (struct evbuf_header *)
 840                                         ((addr_t) evbuf + evbuf->length);
 841                 }
 842         }
 843
 844         return unprocessed;
 845 }
 846
 847 module_init(sclp_init);
 848
 849 EXPORT_SYMBOL(sclp_add_request);
 850 EXPORT_SYMBOL(sclp_sync_wait);
 851 EXPORT_SYMBOL(sclp_register);
 852 EXPORT_SYMBOL(sclp_unregister);
 853 EXPORT_SYMBOL(sclp_error_message);