drivers/watchdog/intel_scu_watchdog.c

   1 /*
   2  *      Intel_SCU 0.2:  An Intel SCU IOH Based Watchdog Device
   3  *                      for Intel part #(s):
   4  *                              - AF82MP20 PCH
   5  *
   6  *      Copyright (C) 2009-2010 Intel Corporation. All rights reserved.
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of version 2 of the GNU General
  10  *      Public License as published by the Free Software Foundation.
  11  *
  12  *      This program is distributed in the hope that it will be
  13  *      useful, but WITHOUT ANY WARRANTY; without even the implied
  14  *      warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  15  *      PURPOSE.  See the GNU General Public License for more details.
  16  *      You should have received a copy of the GNU General Public
  17  *      License along with this program; if not, write to the Free
  18  *      Software Foundation, Inc., 59 Temple Place - Suite 330,
  19  *      Boston, MA  02111-1307, USA.
  20  *      The full GNU General Public License is included in this
  21  *      distribution in the file called COPYING.
  22  *
  23  */
  24
  25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  26
  27 #include <linux/compiler.h>
  28 #include <linux/module.h>
  29 #include <linux/kernel.h>
  30 #include <linux/moduleparam.h>
  31 #include <linux/types.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/watchdog.h>
  34 #include <linux/fs.h>
  35 #include <linux/notifier.h>
  36 #include <linux/reboot.h>
  37 #include <linux/init.h>
  38 #include <linux/jiffies.h>
  39 #include <linux/uaccess.h>
  40 #include <linux/slab.h>
  41 #include <linux/io.h>
  42 #include <linux/interrupt.h>
  43 #include <linux/delay.h>
  44 #include <linux/sched.h>
  45 #include <linux/signal.h>
  46 #include <linux/sfi.h>
  47 #include <asm/irq.h>
  48 #include <linux/atomic.h>
  49 #include <asm/intel_scu_ipc.h>
  50 #include <asm/apb_timer.h>
  51 #include <asm/mrst.h>
  52
  53 #include "intel_scu_watchdog.h"
  54
  55 /* Bounds number of times we will retry loading time count */
  56 /* This retry is a work around for a silicon bug.          */
  57 #define MAX_RETRY 16
  58
  59 #define IPC_SET_WATCHDOG_TIMER  0xF8
  60
  61 static int timer_margin = DEFAULT_SOFT_TO_HARD_MARGIN;
  62 module_param(timer_margin, int, 0);
  63 MODULE_PARM_DESC(timer_margin,
  64                 "Watchdog timer margin"
  65                 "Time between interrupt and resetting the system"
  66                 "The range is from 1 to 160"
  67                 "This is the time for all keep alives to arrive");
  68
  69 static int timer_set = DEFAULT_TIME;
  70 module_param(timer_set, int, 0);
  71 MODULE_PARM_DESC(timer_set,
  72                 "Default Watchdog timer setting"
  73                 "Complete cycle time"
  74                 "The range is from 1 to 170"
  75                 "This is the time for all keep alives to arrive");
  76
  77 /* After watchdog device is closed, check force_boot. If:
  78  * force_boot == 0, then force boot on next watchdog interrupt after close,
  79  * force_boot == 1, then force boot immediately when device is closed.
  80  */
  81 static int force_boot;
  82 module_param(force_boot, int, 0);
  83 MODULE_PARM_DESC(force_boot,
  84                 "A value of 1 means that the driver will reboot"
  85                 "the system immediately if the /dev/watchdog device is closed"
  86                 "A value of 0 means that when /dev/watchdog device is closed"
  87                 "the watchdog timer will be refreshed for one more interval"
  88                 "of length: timer_set. At the end of this interval, the"
  89                 "watchdog timer will reset the system."
  90                 );
  91
  92 /* there is only one device in the system now; this can be made into
  93  * an array in the future if we have more than one device */
  94
  95 static struct intel_scu_watchdog_dev watchdog_device;
  96
  97 /* Forces restart, if force_reboot is set */
  98 static void watchdog_fire(void)
  99 {
 100         if (force_boot) {
 101                 pr_crit("Initiating system reboot\n");
 102                 emergency_restart();
 103                 pr_crit("Reboot didn't ?????\n");
 104         }
 105
 106         else {
 107                 pr_crit("Immediate Reboot Disabled\n");
 108                 pr_crit("System will reset when watchdog timer times out!\n");
 109         }
 110 }
 111
 112 static int check_timer_margin(int new_margin)
 113 {
 114         if ((new_margin < MIN_TIME_CYCLE) ||
 115             (new_margin > MAX_TIME - timer_set)) {
 116                 pr_debug("value of new_margin %d is out of the range %d to %d\n",
 117                          new_margin, MIN_TIME_CYCLE, MAX_TIME - timer_set);
 118                 return -EINVAL;
 119         }
 120         return 0;
 121 }
 122
 123 /*
 124  * IPC operations
 125  */
 126 static int watchdog_set_ipc(int soft_threshold, int threshold)
 127 {
 128         u32     *ipc_wbuf;
 129         u8       cbuf[16] = { '\0' };
 130         int      ipc_ret = 0;
 131
 132         ipc_wbuf = (u32 *)&cbuf;
 133         ipc_wbuf[0] = soft_threshold;
 134         ipc_wbuf[1] = threshold;
 135
 136         ipc_ret = intel_scu_ipc_command(
 137                         IPC_SET_WATCHDOG_TIMER,
 138                         0,
 139                         ipc_wbuf,
 140                         2,
 141                         NULL,
 142                         0);
 143
 144         if (ipc_ret != 0)
 145                 pr_err("Error setting SCU watchdog timer: %x\n", ipc_ret);
 146
 147         return ipc_ret;
 148 };
 149
 150 /*
 151  *      Intel_SCU operations
 152  */
 153
 154 /* timer interrupt handler */
 155 static irqreturn_t watchdog_timer_interrupt(int irq, void *dev_id)
 156 {
 157         int int_status;
 158         int_status = ioread32(watchdog_device.timer_interrupt_status_addr);
 159
 160         pr_debug("irq, int_status: %x\n", int_status);
 161
 162         if (int_status != 0)
 163                 return IRQ_NONE;
 164
 165         /* has the timer been started? If not, then this is spurious */
 166         if (watchdog_device.timer_started == 0) {
 167                 pr_debug("spurious interrupt received\n");
 168                 return IRQ_HANDLED;
 169         }
 170
 171         /* temporarily disable the timer */
 172         iowrite32(0x00000002, watchdog_device.timer_control_addr);
 173
 174         /* set the timer to the threshold */
 175         iowrite32(watchdog_device.threshold,
 176                   watchdog_device.timer_load_count_addr);
 177
 178         /* allow the timer to run */
 179         iowrite32(0x00000003, watchdog_device.timer_control_addr);
 180
 181         return IRQ_HANDLED;
 182 }
 183
 184 static int intel_scu_keepalive(void)
 185 {
 186
 187         /* read eoi register - clears interrupt */
 188         ioread32(watchdog_device.timer_clear_interrupt_addr);
 189
 190         /* temporarily disable the timer */
 191         iowrite32(0x00000002, watchdog_device.timer_control_addr);
 192
 193         /* set the timer to the soft_threshold */
 194         iowrite32(watchdog_device.soft_threshold,
 195                   watchdog_device.timer_load_count_addr);
 196
 197         /* allow the timer to run */
 198         iowrite32(0x00000003, watchdog_device.timer_control_addr);
 199
 200         return 0;
 201 }
 202
 203 static int intel_scu_stop(void)
 204 {
 205         iowrite32(0, watchdog_device.timer_control_addr);
 206         return 0;
 207 }
 208
 209 static int intel_scu_set_heartbeat(u32 t)
 210 {
 211         int                      ipc_ret;
 212         int                      retry_count;
 213         u32                      soft_value;
 214         u32                      hw_pre_value;
 215         u32                      hw_value;
 216
 217         watchdog_device.timer_set = t;
 218         watchdog_device.threshold =
 219                 timer_margin * watchdog_device.timer_tbl_ptr->freq_hz;
 220         watchdog_device.soft_threshold =
 221                 (watchdog_device.timer_set - timer_margin)
 222                 * watchdog_device.timer_tbl_ptr->freq_hz;
 223
 224         pr_debug("set_heartbeat: timer freq is %d\n",
 225                  watchdog_device.timer_tbl_ptr->freq_hz);
 226         pr_debug("set_heartbeat: timer_set is %x (hex)\n",
 227                  watchdog_device.timer_set);
 228         pr_debug("set_hearbeat: timer_margin is %x (hex)\n", timer_margin);
 229         pr_debug("set_heartbeat: threshold is %x (hex)\n",
 230                  watchdog_device.threshold);
 231         pr_debug("set_heartbeat: soft_threshold is %x (hex)\n",
 232                  watchdog_device.soft_threshold);
 233
 234         /* Adjust thresholds by FREQ_ADJUSTMENT factor, to make the */
 235         /* watchdog timing come out right. */
 236         watchdog_device.threshold =
 237                 watchdog_device.threshold / FREQ_ADJUSTMENT;
 238         watchdog_device.soft_threshold =
 239                 watchdog_device.soft_threshold / FREQ_ADJUSTMENT;
 240
 241         /* temporarily disable the timer */
 242         iowrite32(0x00000002, watchdog_device.timer_control_addr);
 243
 244         /* send the threshold and soft_threshold via IPC to the processor */
 245         ipc_ret = watchdog_set_ipc(watchdog_device.soft_threshold,
 246                                    watchdog_device.threshold);
 247
 248         if (ipc_ret != 0) {
 249                 /* Make sure the watchdog timer is stopped */
 250                 intel_scu_stop();
 251                 return ipc_ret;
 252         }
 253
 254         /* Soft Threshold set loop. Early versions of silicon did */
 255         /* not always set this count correctly.  This loop checks */
 256         /* the value and retries if it was not set correctly.     */
 257
 258         retry_count = 0;
 259         soft_value = watchdog_device.soft_threshold & 0xFFFF0000;
 260         do {
 261
 262                 /* Make sure timer is stopped */
 263                 intel_scu_stop();
 264
 265                 if (MAX_RETRY < retry_count++) {
 266                         /* Unable to set timer value */
 267                         pr_err("Unable to set timer\n");
 268                         return -ENODEV;
 269                 }
 270
 271                 /* set the timer to the soft threshold */
 272                 iowrite32(watchdog_device.soft_threshold,
 273                         watchdog_device.timer_load_count_addr);
 274
 275                 /* read count value before starting timer */
 276                 hw_pre_value = ioread32(watchdog_device.timer_load_count_addr);
 277                 hw_pre_value = hw_pre_value & 0xFFFF0000;
 278
 279                 /* Start the timer */
 280                 iowrite32(0x00000003, watchdog_device.timer_control_addr);
 281
 282                 /* read the value the time loaded into its count reg */
 283                 hw_value = ioread32(watchdog_device.timer_load_count_addr);
 284                 hw_value = hw_value & 0xFFFF0000;
 285
 286
 287         } while (soft_value != hw_value);
 288
 289         watchdog_device.timer_started = 1;
 290
 291         return 0;
 292 }
 293
 294 /*
 295  * /dev/watchdog handling
 296  */
 297
 298 static int intel_scu_open(struct inode *inode, struct file *file)
 299 {
 300
 301         /* Set flag to indicate that watchdog device is open */
 302         if (test_and_set_bit(0, &watchdog_device.driver_open))
 303                 return -EBUSY;
 304
 305         /* Check for reopen of driver. Reopens are not allowed */
 306         if (watchdog_device.driver_closed)
 307                 return -EPERM;
 308
 309         return nonseekable_open(inode, file);
 310 }
 311
 312 static int intel_scu_release(struct inode *inode, struct file *file)
 313 {
 314         /*
 315          * This watchdog should not be closed, after the timer
 316          * is started with the WDIPC_SETTIMEOUT ioctl
 317          * If force_boot is set watchdog_fire() will cause an
 318          * immediate reset. If force_boot is not set, the watchdog
 319          * timer is refreshed for one more interval. At the end
 320          * of that interval, the watchdog timer will reset the system.
 321          */
 322
 323         if (!test_and_clear_bit(0, &watchdog_device.driver_open)) {
 324                 pr_debug("intel_scu_release, without open\n");
 325                 return -ENOTTY;
 326         }
 327
 328         if (!watchdog_device.timer_started) {
 329                 /* Just close, since timer has not been started */
 330                 pr_debug("closed, without starting timer\n");
 331                 return 0;
 332         }
 333
 334         pr_crit("Unexpected close of /dev/watchdog!\n");
 335
 336         /* Since the timer was started, prevent future reopens */
 337         watchdog_device.driver_closed = 1;
 338
 339         /* Refresh the timer for one more interval */
 340         intel_scu_keepalive();
 341
 342         /* Reboot system (if force_boot is set) */
 343         watchdog_fire();
 344
 345         /* We should only reach this point if force_boot is not set */
 346         return 0;
 347 }
 348
 349 static ssize_t intel_scu_write(struct file *file,
 350                               char const *data,
 351                               size_t len,
 352                               loff_t *ppos)
 353 {
 354
 355         if (watchdog_device.timer_started)
 356                 /* Watchdog already started, keep it alive */
 357                 intel_scu_keepalive();
 358         else
 359                 /* Start watchdog with timer value set by init */
 360                 intel_scu_set_heartbeat(watchdog_device.timer_set);
 361
 362         return len;
 363 }
 364
 365 static long intel_scu_ioctl(struct file *file,
 366                            unsigned int cmd,
 367                            unsigned long arg)
 368 {
 369         void __user *argp = (void __user *)arg;
 370         u32 __user *p = argp;
 371         u32 new_margin;
 372
 373
 374         static const struct watchdog_info ident = {
 375                 .options =          WDIOF_SETTIMEOUT
 376                                     | WDIOF_KEEPALIVEPING,
 377                 .firmware_version = 0,  /* @todo Get from SCU via
 378                                                  ipc_get_scu_fw_version()? */
 379                 .identity =         "Intel_SCU IOH Watchdog"  /* len < 32 */
 380         };
 381
 382         switch (cmd) {
 383         case WDIOC_GETSUPPORT:
 384                 return copy_to_user(argp,
 385                                     &ident,
 386                                     sizeof(ident)) ? -EFAULT : 0;
 387         case WDIOC_GETSTATUS:
 388         case WDIOC_GETBOOTSTATUS:
 389                 return put_user(0, p);
 390         case WDIOC_KEEPALIVE:
 391                 intel_scu_keepalive();
 392
 393                 return 0;
 394         case WDIOC_SETTIMEOUT:
 395                 if (get_user(new_margin, p))
 396                         return -EFAULT;
 397
 398                 if (check_timer_margin(new_margin))
 399                         return -EINVAL;
 400
 401                 if (intel_scu_set_heartbeat(new_margin))
 402                         return -EINVAL;
 403                 return 0;
 404         case WDIOC_GETTIMEOUT:
 405                 return put_user(watchdog_device.soft_threshold, p);
 406
 407         default:
 408                 return -ENOTTY;
 409         }
 410 }
 411
 412 /*
 413  *      Notifier for system down
 414  */
 415 static int intel_scu_notify_sys(struct notifier_block *this,
 416                                unsigned long code,
 417                                void *another_unused)
 418 {
 419         if (code == SYS_DOWN || code == SYS_HALT)
 420                 /* Turn off the watchdog timer. */
 421                 intel_scu_stop();
 422         return NOTIFY_DONE;
 423 }
 424
 425 /*
 426  *      Kernel Interfaces
 427  */
 428 static const struct file_operations intel_scu_fops = {
 429         .owner          = THIS_MODULE,
 430         .llseek         = no_llseek,
 431         .write          = intel_scu_write,
 432         .unlocked_ioctl = intel_scu_ioctl,
 433         .open           = intel_scu_open,
 434         .release        = intel_scu_release,
 435 };
 436
 437 static int __init intel_scu_watchdog_init(void)
 438 {
 439         int ret;
 440         u32 __iomem *tmp_addr;
 441
 442         /*
 443          * We don't really need to check this as the SFI timer get will fail
 444          * but if we do so we can exit with a clearer reason and no noise.
 445          *
 446          * If it isn't an intel MID device then it doesn't have this watchdog
 447          */
 448         if (!mrst_identify_cpu())
 449                 return -ENODEV;
 450
 451         /* Check boot parameters to verify that their initial values */
 452         /* are in range. */
 453         /* Check value of timer_set boot parameter */
 454         if ((timer_set < MIN_TIME_CYCLE) ||
 455             (timer_set > MAX_TIME - MIN_TIME_CYCLE)) {
 456                 pr_err("value of timer_set %x (hex) is out of range from %x to %x (hex)\n",
 457                        timer_set, MIN_TIME_CYCLE, MAX_TIME - MIN_TIME_CYCLE);
 458                 return -EINVAL;
 459         }
 460
 461         /* Check value of timer_margin boot parameter */
 462         if (check_timer_margin(timer_margin))
 463                 return -EINVAL;
 464
 465         watchdog_device.timer_tbl_ptr = sfi_get_mtmr(sfi_mtimer_num-1);
 466
 467         if (watchdog_device.timer_tbl_ptr == NULL) {
 468                 pr_debug("timer is not available\n");
 469                 return -ENODEV;
 470         }
 471         /* make sure the timer exists */
 472         if (watchdog_device.timer_tbl_ptr->phys_addr == 0) {
 473                 pr_debug("timer %d does not have valid physical memory\n",
 474                          sfi_mtimer_num);
 475                 return -ENODEV;
 476         }
 477
 478         if (watchdog_device.timer_tbl_ptr->irq == 0) {
 479                 pr_debug("timer %d invalid irq\n", sfi_mtimer_num);
 480                 return -ENODEV;
 481         }
 482
 483         tmp_addr = ioremap_nocache(watchdog_device.timer_tbl_ptr->phys_addr,
 484                         20);
 485
 486         if (tmp_addr == NULL) {
 487                 pr_debug("timer unable to ioremap\n");
 488                 return -ENOMEM;
 489         }
 490
 491         watchdog_device.timer_load_count_addr = tmp_addr++;
 492         watchdog_device.timer_current_value_addr = tmp_addr++;
 493         watchdog_device.timer_control_addr = tmp_addr++;
 494         watchdog_device.timer_clear_interrupt_addr = tmp_addr++;
 495         watchdog_device.timer_interrupt_status_addr = tmp_addr++;
 496
 497         /* Set the default time values in device structure */
 498
 499         watchdog_device.timer_set = timer_set;
 500         watchdog_device.threshold =
 501                 timer_margin * watchdog_device.timer_tbl_ptr->freq_hz;
 502         watchdog_device.soft_threshold =
 503                 (watchdog_device.timer_set - timer_margin)
 504                 * watchdog_device.timer_tbl_ptr->freq_hz;
 505
 506
 507         watchdog_device.intel_scu_notifier.notifier_call =
 508                 intel_scu_notify_sys;
 509
 510         ret = register_reboot_notifier(&watchdog_device.intel_scu_notifier);
 511         if (ret) {
 512                 pr_err("cannot register notifier %d)\n", ret);
 513                 goto register_reboot_error;
 514         }
 515
 516         watchdog_device.miscdev.minor = WATCHDOG_MINOR;
 517         watchdog_device.miscdev.name = "watchdog";
 518         watchdog_device.miscdev.fops = &intel_scu_fops;
 519
 520         ret = misc_register(&watchdog_device.miscdev);
 521         if (ret) {
 522                 pr_err("cannot register miscdev %d err =%d\n",
 523                        WATCHDOG_MINOR, ret);
 524                 goto misc_register_error;
 525         }
 526
 527         ret = request_irq((unsigned int)watchdog_device.timer_tbl_ptr->irq,
 528                 watchdog_timer_interrupt,
 529                 IRQF_SHARED, "watchdog",
 530                 &watchdog_device.timer_load_count_addr);
 531         if (ret) {
 532                 pr_err("error requesting irq %d\n", ret);
 533                 goto request_irq_error;
 534         }
 535         /* Make sure timer is disabled before returning */
 536         intel_scu_stop();
 537         return 0;
 538
 539 /* error cleanup */
 540
 541 request_irq_error:
 542         misc_deregister(&watchdog_device.miscdev);
 543 misc_register_error:
 544         unregister_reboot_notifier(&watchdog_device.intel_scu_notifier);
 545 register_reboot_error:
 546         intel_scu_stop();
 547         iounmap(watchdog_device.timer_load_count_addr);
 548         return ret;
 549 }
 550
 551 static void __exit intel_scu_watchdog_exit(void)
 552 {
 553
 554         misc_deregister(&watchdog_device.miscdev);
 555         unregister_reboot_notifier(&watchdog_device.intel_scu_notifier);
 556         /* disable the timer */
 557         iowrite32(0x00000002, watchdog_device.timer_control_addr);
 558         iounmap(watchdog_device.timer_load_count_addr);
 559 }
 560
 561 late_initcall(intel_scu_watchdog_init);
 562 module_exit(intel_scu_watchdog_exit);
 563
 564 MODULE_AUTHOR("Intel Corporation");
 565 MODULE_DESCRIPTION("Intel SCU Watchdog Device Driver");
 566 MODULE_LICENSE("GPL");
 567 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 568 MODULE_VERSION(WDT_VER);