drivers/pci/hotplug/pciehp_ctrl.c

   1 /*
   2  * PCI Express Hot Plug Controller Driver
   3  *
   4  * Copyright (C) 1995,2001 Compaq Computer Corporation
   5  * Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
   6  * Copyright (C) 2001 IBM Corp.
   7  * Copyright (C) 2003-2004 Intel Corporation
   8  *
   9  * All rights reserved.
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or (at
  14  * your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful, but
  17  * WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  19  * NON INFRINGEMENT.  See the GNU General Public License for more
  20  * details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  25  *
  26  * Send feedback to <greg@kroah.com>, <kristen.c.accardi@intel.com>
  27  *
  28  */
  29
  30 #include <linux/module.h>
  31 #include <linux/kernel.h>
  32 #include <linux/types.h>
  33 #include <linux/smp_lock.h>
  34 #include <linux/pci.h>
  35 #include <linux/workqueue.h>
  36 #include "../pci.h"
  37 #include "pciehp.h"
  38
  39 static void interrupt_event_handler(struct work_struct *work);
  40
  41 static int queue_interrupt_event(struct slot *p_slot, u32 event_type)
  42 {
  43         struct event_info *info;
  44
  45         info = kmalloc(sizeof(*info), GFP_ATOMIC);
  46         if (!info)
  47                 return -ENOMEM;
  48
  49         info->event_type = event_type;
  50         info->p_slot = p_slot;
  51         INIT_WORK(&info->work, interrupt_event_handler);
  52
  53         schedule_work(&info->work);
  54
  55         return 0;
  56 }
  57
  58 u8 pciehp_handle_attention_button(u8 hp_slot, struct controller *ctrl)
  59 {
  60         struct slot *p_slot;
  61         u32 event_type;
  62
  63         /* Attention Button Change */
  64         dbg("pciehp:  Attention button interrupt received.\n");
  65
  66         p_slot = pciehp_find_slot(ctrl, hp_slot + ctrl->slot_device_offset);
  67
  68         /*
  69          *  Button pressed - See if need to TAKE ACTION!!!
  70          */
  71         info("Button pressed on Slot(%s)\n", p_slot->name);
  72         event_type = INT_BUTTON_PRESS;
  73
  74         queue_interrupt_event(p_slot, event_type);
  75
  76         return 0;
  77 }
  78
  79 u8 pciehp_handle_switch_change(u8 hp_slot, struct controller *ctrl)
  80 {
  81         struct slot *p_slot;
  82         u8 getstatus;
  83         u32 event_type;
  84
  85         /* Switch Change */
  86         dbg("pciehp:  Switch interrupt received.\n");
  87
  88         p_slot = pciehp_find_slot(ctrl, hp_slot + ctrl->slot_device_offset);
  89         p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
  90
  91         if (getstatus) {
  92                 /*
  93                  * Switch opened
  94                  */
  95                 info("Latch open on Slot(%s)\n", p_slot->name);
  96                 event_type = INT_SWITCH_OPEN;
  97         } else {
  98                 /*
  99                  *  Switch closed
 100                  */
 101                 info("Latch close on Slot(%s)\n", p_slot->name);
 102                 event_type = INT_SWITCH_CLOSE;
 103         }
 104
 105         queue_interrupt_event(p_slot, event_type);
 106
 107         return 1;
 108 }
 109
 110 u8 pciehp_handle_presence_change(u8 hp_slot, struct controller *ctrl)
 111 {
 112         struct slot *p_slot;
 113         u32 event_type;
 114         u8 presence_save;
 115
 116         /* Presence Change */
 117         dbg("pciehp:  Presence/Notify input change.\n");
 118
 119         p_slot = pciehp_find_slot(ctrl, hp_slot + ctrl->slot_device_offset);
 120
 121         /* Switch is open, assume a presence change
 122          * Save the presence state
 123          */
 124         p_slot->hpc_ops->get_adapter_status(p_slot, &presence_save);
 125         if (presence_save) {
 126                 /*
 127                  * Card Present
 128                  */
 129                 info("Card present on Slot(%s)\n", p_slot->name);
 130                 event_type = INT_PRESENCE_ON;
 131         } else {
 132                 /*
 133                  * Not Present
 134                  */
 135                 info("Card not present on Slot(%s)\n", p_slot->name);
 136                 event_type = INT_PRESENCE_OFF;
 137         }
 138
 139         queue_interrupt_event(p_slot, event_type);
 140
 141         return 1;
 142 }
 143
 144 u8 pciehp_handle_power_fault(u8 hp_slot, struct controller *ctrl)
 145 {
 146         struct slot *p_slot;
 147         u32 event_type;
 148
 149         /* power fault */
 150         dbg("pciehp:  Power fault interrupt received.\n");
 151
 152         p_slot = pciehp_find_slot(ctrl, hp_slot + ctrl->slot_device_offset);
 153
 154         if ( !(p_slot->hpc_ops->query_power_fault(p_slot))) {
 155                 /*
 156                  * power fault Cleared
 157                  */
 158                 info("Power fault cleared on Slot(%s)\n", p_slot->name);
 159                 event_type = INT_POWER_FAULT_CLEAR;
 160         } else {
 161                 /*
 162                  *   power fault
 163                  */
 164                 info("Power fault on Slot(%s)\n", p_slot->name);
 165                 event_type = INT_POWER_FAULT;
 166                 info("power fault bit %x set\n", hp_slot);
 167         }
 168
 169         queue_interrupt_event(p_slot, event_type);
 170
 171         return 1;
 172 }
 173
 174 /* The following routines constitute the bulk of the
 175    hotplug controller logic
 176  */
 177
 178 static void set_slot_off(struct controller *ctrl, struct slot * pslot)
 179 {
 180         /* turn off slot, turn on Amber LED, turn off Green LED if supported*/
 181         if (POWER_CTRL(ctrl->ctrlcap)) {
 182                 if (pslot->hpc_ops->power_off_slot(pslot)) {
 183                         err("%s: Issue of Slot Power Off command failed\n",
 184                             __func__);
 185                         return;
 186                 }
 187         }
 188
 189         if (PWR_LED(ctrl->ctrlcap))
 190                 pslot->hpc_ops->green_led_off(pslot);
 191
 192         if (ATTN_LED(ctrl->ctrlcap)) {
 193                 if (pslot->hpc_ops->set_attention_status(pslot, 1)) {
 194                         err("%s: Issue of Set Attention Led command failed\n",
 195                             __func__);
 196                         return;
 197                 }
 198         }
 199 }
 200
 201 /**
 202  * board_added - Called after a board has been added to the system.
 203  * @p_slot: &slot where board is added
 204  *
 205  * Turns power on for the board.
 206  * Configures board.
 207  */
 208 static int board_added(struct slot *p_slot)
 209 {
 210         int retval = 0;
 211         struct controller *ctrl = p_slot->ctrl;
 212
 213         dbg("%s: slot device, slot offset, hp slot = %d, %d ,%d\n",
 214                         __func__, p_slot->device,
 215                         ctrl->slot_device_offset, p_slot->hp_slot);
 216
 217         if (POWER_CTRL(ctrl->ctrlcap)) {
 218                 /* Power on slot */
 219                 retval = p_slot->hpc_ops->power_on_slot(p_slot);
 220                 if (retval)
 221                         return retval;
 222         }
 223
 224         if (PWR_LED(ctrl->ctrlcap))
 225                 p_slot->hpc_ops->green_led_blink(p_slot);
 226
 227         /* Wait for ~1 second */
 228         msleep(1000);
 229
 230         /* Check link training status */
 231         retval = p_slot->hpc_ops->check_lnk_status(ctrl);
 232         if (retval) {
 233                 err("%s: Failed to check link status\n", __func__);
 234                 set_slot_off(ctrl, p_slot);
 235                 return retval;
 236         }
 237
 238         /* Check for a power fault */
 239         if (p_slot->hpc_ops->query_power_fault(p_slot)) {
 240                 dbg("%s: power fault detected\n", __func__);
 241                 retval = POWER_FAILURE;
 242                 goto err_exit;
 243         }
 244
 245         retval = pciehp_configure_device(p_slot);
 246         if (retval) {
 247                 err("Cannot add device 0x%x:%x\n", p_slot->bus,
 248                     p_slot->device);
 249                 goto err_exit;
 250         }
 251
 252         /*
 253          * Some PCI Express root ports require fixup after hot-plug operation.
 254          */
 255         if (pcie_mch_quirk)
 256                 pci_fixup_device(pci_fixup_final, ctrl->pci_dev);
 257         if (PWR_LED(ctrl->ctrlcap))
 258                 p_slot->hpc_ops->green_led_on(p_slot);
 259
 260         return 0;
 261
 262 err_exit:
 263         set_slot_off(ctrl, p_slot);
 264         return retval;
 265 }
 266
 267 /**
 268  * remove_board - Turns off slot and LEDs
 269  * @p_slot: slot where board is being removed
 270  */
 271 static int remove_board(struct slot *p_slot)
 272 {
 273         int retval = 0;
 274         struct controller *ctrl = p_slot->ctrl;
 275
 276         retval = pciehp_unconfigure_device(p_slot);
 277         if (retval)
 278                 return retval;
 279
 280         dbg("In %s, hp_slot = %d\n", __func__, p_slot->hp_slot);
 281
 282         if (POWER_CTRL(ctrl->ctrlcap)) {
 283                 /* power off slot */
 284                 retval = p_slot->hpc_ops->power_off_slot(p_slot);
 285                 if (retval) {
 286                         err("%s: Issue of Slot Disable command failed\n",
 287                             __func__);
 288                         return retval;
 289                 }
 290         }
 291
 292         if (PWR_LED(ctrl->ctrlcap))
 293                 /* turn off Green LED */
 294                 p_slot->hpc_ops->green_led_off(p_slot);
 295
 296         return 0;
 297 }
 298
 299 struct power_work_info {
 300         struct slot *p_slot;
 301         struct work_struct work;
 302 };
 303
 304 /**
 305  * pciehp_power_thread - handle pushbutton events
 306  * @work: &struct work_struct describing work to be done
 307  *
 308  * Scheduled procedure to handle blocking stuff for the pushbuttons.
 309  * Handles all pending events and exits.
 310  */
 311 static void pciehp_power_thread(struct work_struct *work)
 312 {
 313         struct power_work_info *info =
 314                 container_of(work, struct power_work_info, work);
 315         struct slot *p_slot = info->p_slot;
 316
 317         mutex_lock(&p_slot->lock);
 318         switch (p_slot->state) {
 319         case POWEROFF_STATE:
 320                 mutex_unlock(&p_slot->lock);
 321                 dbg("%s: disabling bus:device(%x:%x)\n",
 322                     __func__, p_slot->bus, p_slot->device);
 323                 pciehp_disable_slot(p_slot);
 324                 mutex_lock(&p_slot->lock);
 325                 p_slot->state = STATIC_STATE;
 326                 break;
 327         case POWERON_STATE:
 328                 mutex_unlock(&p_slot->lock);
 329                 if (pciehp_enable_slot(p_slot) &&
 330                     PWR_LED(p_slot->ctrl->ctrlcap))
 331                         p_slot->hpc_ops->green_led_off(p_slot);
 332                 mutex_lock(&p_slot->lock);
 333                 p_slot->state = STATIC_STATE;
 334                 break;
 335         default:
 336                 break;
 337         }
 338         mutex_unlock(&p_slot->lock);
 339
 340         kfree(info);
 341 }
 342
 343 void pciehp_queue_pushbutton_work(struct work_struct *work)
 344 {
 345         struct slot *p_slot = container_of(work, struct slot, work.work);
 346         struct power_work_info *info;
 347
 348         info = kmalloc(sizeof(*info), GFP_KERNEL);
 349         if (!info) {
 350                 err("%s: Cannot allocate memory\n", __func__);
 351                 return;
 352         }
 353         info->p_slot = p_slot;
 354         INIT_WORK(&info->work, pciehp_power_thread);
 355
 356         mutex_lock(&p_slot->lock);
 357         switch (p_slot->state) {
 358         case BLINKINGOFF_STATE:
 359                 p_slot->state = POWEROFF_STATE;
 360                 break;
 361         case BLINKINGON_STATE:
 362                 p_slot->state = POWERON_STATE;
 363                 break;
 364         default:
 365                 goto out;
 366         }
 367         queue_work(pciehp_wq, &info->work);
 368  out:
 369         mutex_unlock(&p_slot->lock);
 370 }
 371
 372 static int update_slot_info(struct slot *slot)
 373 {
 374         struct hotplug_slot_info *info;
 375         int result;
 376
 377         info = kmalloc(sizeof(*info), GFP_KERNEL);
 378         if (!info)
 379                 return -ENOMEM;
 380
 381         slot->hpc_ops->get_power_status(slot, &(info->power_status));
 382         slot->hpc_ops->get_attention_status(slot, &(info->attention_status));
 383         slot->hpc_ops->get_latch_status(slot, &(info->latch_status));
 384         slot->hpc_ops->get_adapter_status(slot, &(info->adapter_status));
 385
 386         result = pci_hp_change_slot_info(slot->hotplug_slot, info);
 387         kfree (info);
 388         return result;
 389 }
 390
 391 /*
 392  * Note: This function must be called with slot->lock held
 393  */
 394 static void handle_button_press_event(struct slot *p_slot)
 395 {
 396         struct controller *ctrl = p_slot->ctrl;
 397         u8 getstatus;
 398
 399         switch (p_slot->state) {
 400         case STATIC_STATE:
 401                 p_slot->hpc_ops->get_power_status(p_slot, &getstatus);
 402                 if (getstatus) {
 403                         p_slot->state = BLINKINGOFF_STATE;
 404                         info("PCI slot #%s - powering off due to button "
 405                              "press.\n", p_slot->name);
 406                 } else {
 407                         p_slot->state = BLINKINGON_STATE;
 408                         info("PCI slot #%s - powering on due to button "
 409                              "press.\n", p_slot->name);
 410                 }
 411                 /* blink green LED and turn off amber */
 412                 if (PWR_LED(ctrl->ctrlcap))
 413                         p_slot->hpc_ops->green_led_blink(p_slot);
 414                 if (ATTN_LED(ctrl->ctrlcap))
 415                         p_slot->hpc_ops->set_attention_status(p_slot, 0);
 416
 417                 schedule_delayed_work(&p_slot->work, 5*HZ);
 418                 break;
 419         case BLINKINGOFF_STATE:
 420         case BLINKINGON_STATE:
 421                 /*
 422                  * Cancel if we are still blinking; this means that we
 423                  * press the attention again before the 5 sec. limit
 424                  * expires to cancel hot-add or hot-remove
 425                  */
 426                 info("Button cancel on Slot(%s)\n", p_slot->name);
 427                 dbg("%s: button cancel\n", __func__);
 428                 cancel_delayed_work(&p_slot->work);
 429                 if (p_slot->state == BLINKINGOFF_STATE) {
 430                         if (PWR_LED(ctrl->ctrlcap))
 431                                 p_slot->hpc_ops->green_led_on(p_slot);
 432                 } else {
 433                         if (PWR_LED(ctrl->ctrlcap))
 434                                 p_slot->hpc_ops->green_led_off(p_slot);
 435                 }
 436                 if (ATTN_LED(ctrl->ctrlcap))
 437                         p_slot->hpc_ops->set_attention_status(p_slot, 0);
 438                 info("PCI slot #%s - action canceled due to button press\n",
 439                      p_slot->name);
 440                 p_slot->state = STATIC_STATE;
 441                 break;
 442         case POWEROFF_STATE:
 443         case POWERON_STATE:
 444                 /*
 445                  * Ignore if the slot is on power-on or power-off state;
 446                  * this means that the previous attention button action
 447                  * to hot-add or hot-remove is undergoing
 448                  */
 449                 info("Button ignore on Slot(%s)\n", p_slot->name);
 450                 update_slot_info(p_slot);
 451                 break;
 452         default:
 453                 warn("Not a valid state\n");
 454                 break;
 455         }
 456 }
 457
 458 /*
 459  * Note: This function must be called with slot->lock held
 460  */
 461 static void handle_surprise_event(struct slot *p_slot)
 462 {
 463         u8 getstatus;
 464         struct power_work_info *info;
 465
 466         info = kmalloc(sizeof(*info), GFP_KERNEL);
 467         if (!info) {
 468                 err("%s: Cannot allocate memory\n", __func__);
 469                 return;
 470         }
 471         info->p_slot = p_slot;
 472         INIT_WORK(&info->work, pciehp_power_thread);
 473
 474         p_slot->hpc_ops->get_adapter_status(p_slot, &getstatus);
 475         if (!getstatus)
 476                 p_slot->state = POWEROFF_STATE;
 477         else
 478                 p_slot->state = POWERON_STATE;
 479
 480         queue_work(pciehp_wq, &info->work);
 481 }
 482
 483 static void interrupt_event_handler(struct work_struct *work)
 484 {
 485         struct event_info *info = container_of(work, struct event_info, work);
 486         struct slot *p_slot = info->p_slot;
 487         struct controller *ctrl = p_slot->ctrl;
 488
 489         mutex_lock(&p_slot->lock);
 490         switch (info->event_type) {
 491         case INT_BUTTON_PRESS:
 492                 handle_button_press_event(p_slot);
 493                 break;
 494         case INT_POWER_FAULT:
 495                 if (!POWER_CTRL(ctrl->ctrlcap))
 496                         break;
 497                 if (ATTN_LED(ctrl->ctrlcap))
 498                         p_slot->hpc_ops->set_attention_status(p_slot, 1);
 499                 if (PWR_LED(ctrl->ctrlcap))
 500                         p_slot->hpc_ops->green_led_off(p_slot);
 501                 break;
 502         case INT_PRESENCE_ON:
 503         case INT_PRESENCE_OFF:
 504                 if (!HP_SUPR_RM(ctrl->ctrlcap))
 505                         break;
 506                 dbg("Surprise Removal\n");
 507                 update_slot_info(p_slot);
 508                 handle_surprise_event(p_slot);
 509                 break;
 510         default:
 511                 update_slot_info(p_slot);
 512                 break;
 513         }
 514         mutex_unlock(&p_slot->lock);
 515
 516         kfree(info);
 517 }
 518
 519 int pciehp_enable_slot(struct slot *p_slot)
 520 {
 521         u8 getstatus = 0;
 522         int rc;
 523
 524         /* Check to see if (latch closed, card present, power off) */
 525         mutex_lock(&p_slot->ctrl->crit_sect);
 526
 527         rc = p_slot->hpc_ops->get_adapter_status(p_slot, &getstatus);
 528         if (rc || !getstatus) {
 529                 info("%s: no adapter on slot(%s)\n", __func__,
 530                      p_slot->name);
 531                 mutex_unlock(&p_slot->ctrl->crit_sect);
 532                 return -ENODEV;
 533         }
 534         if (MRL_SENS(p_slot->ctrl->ctrlcap)) {
 535                 rc = p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
 536                 if (rc || getstatus) {
 537                         info("%s: latch open on slot(%s)\n", __func__,
 538                              p_slot->name);
 539                         mutex_unlock(&p_slot->ctrl->crit_sect);
 540                         return -ENODEV;
 541                 }
 542         }
 543
 544         if (POWER_CTRL(p_slot->ctrl->ctrlcap)) {
 545                 rc = p_slot->hpc_ops->get_power_status(p_slot, &getstatus);
 546                 if (rc || getstatus) {
 547                         info("%s: already enabled on slot(%s)\n", __func__,
 548                              p_slot->name);
 549                         mutex_unlock(&p_slot->ctrl->crit_sect);
 550                         return -EINVAL;
 551                 }
 552         }
 553
 554         p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
 555
 556         rc = board_added(p_slot);
 557         if (rc) {
 558                 p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
 559         }
 560
 561         update_slot_info(p_slot);
 562
 563         mutex_unlock(&p_slot->ctrl->crit_sect);
 564         return rc;
 565 }
 566
 567
 568 int pciehp_disable_slot(struct slot *p_slot)
 569 {
 570         u8 getstatus = 0;
 571         int ret = 0;
 572
 573         if (!p_slot->ctrl)
 574                 return 1;
 575
 576         /* Check to see if (latch closed, card present, power on) */
 577         mutex_lock(&p_slot->ctrl->crit_sect);
 578
 579         if (!HP_SUPR_RM(p_slot->ctrl->ctrlcap)) {
 580                 ret = p_slot->hpc_ops->get_adapter_status(p_slot, &getstatus);
 581                 if (ret || !getstatus) {
 582                         info("%s: no adapter on slot(%s)\n", __func__,
 583                              p_slot->name);
 584                         mutex_unlock(&p_slot->ctrl->crit_sect);
 585                         return -ENODEV;
 586                 }
 587         }
 588
 589         if (MRL_SENS(p_slot->ctrl->ctrlcap)) {
 590                 ret = p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
 591                 if (ret || getstatus) {
 592                         info("%s: latch open on slot(%s)\n", __func__,
 593                              p_slot->name);
 594                         mutex_unlock(&p_slot->ctrl->crit_sect);
 595                         return -ENODEV;
 596                 }
 597         }
 598
 599         if (POWER_CTRL(p_slot->ctrl->ctrlcap)) {
 600                 ret = p_slot->hpc_ops->get_power_status(p_slot, &getstatus);
 601                 if (ret || !getstatus) {
 602                         info("%s: already disabled slot(%s)\n", __func__,
 603                              p_slot->name);
 604                         mutex_unlock(&p_slot->ctrl->crit_sect);
 605                         return -EINVAL;
 606                 }
 607         }
 608
 609         ret = remove_board(p_slot);
 610         update_slot_info(p_slot);
 611
 612         mutex_unlock(&p_slot->ctrl->crit_sect);
 613         return ret;
 614 }
 615
 616 int pciehp_sysfs_enable_slot(struct slot *p_slot)
 617 {
 618         int retval = -ENODEV;
 619
 620         mutex_lock(&p_slot->lock);
 621         switch (p_slot->state) {
 622         case BLINKINGON_STATE:
 623                 cancel_delayed_work(&p_slot->work);
 624         case STATIC_STATE:
 625                 p_slot->state = POWERON_STATE;
 626                 mutex_unlock(&p_slot->lock);
 627                 retval = pciehp_enable_slot(p_slot);
 628                 mutex_lock(&p_slot->lock);
 629                 p_slot->state = STATIC_STATE;
 630                 break;
 631         case POWERON_STATE:
 632                 info("Slot %s is already in powering on state\n",
 633                      p_slot->name);
 634                 break;
 635         case BLINKINGOFF_STATE:
 636         case POWEROFF_STATE:
 637                 info("Already enabled on slot %s\n", p_slot->name);
 638                 break;
 639         default:
 640                 err("Not a valid state on slot %s\n", p_slot->name);
 641                 break;
 642         }
 643         mutex_unlock(&p_slot->lock);
 644
 645         return retval;
 646 }
 647
 648 int pciehp_sysfs_disable_slot(struct slot *p_slot)
 649 {
 650         int retval = -ENODEV;
 651
 652         mutex_lock(&p_slot->lock);
 653         switch (p_slot->state) {
 654         case BLINKINGOFF_STATE:
 655                 cancel_delayed_work(&p_slot->work);
 656         case STATIC_STATE:
 657                 p_slot->state = POWEROFF_STATE;
 658                 mutex_unlock(&p_slot->lock);
 659                 retval = pciehp_disable_slot(p_slot);
 660                 mutex_lock(&p_slot->lock);
 661                 p_slot->state = STATIC_STATE;
 662                 break;
 663         case POWEROFF_STATE:
 664                 info("Slot %s is already in powering off state\n",
 665                      p_slot->name);
 666                 break;
 667         case BLINKINGON_STATE:
 668         case POWERON_STATE:
 669                 info("Already disabled on slot %s\n", p_slot->name);
 670                 break;
 671         default:
 672                 err("Not a valid state on slot %s\n", p_slot->name);
 673                 break;
 674         }
 675         mutex_unlock(&p_slot->lock);
 676
 677         return retval;
 678 }