drivers/idle/i7300_idle.c

   1 /*
   2  * (C) Copyright 2008 Intel Corporation
   3  * Authors:
   4  * Andy Henroid <andrew.d.henroid@intel.com>
   5  * Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   6  */
   7
   8 /*
   9  * Save DIMM power on Intel 7300-based platforms when all CPUs/cores
  10  * are idle, using the DIMM thermal throttling capability.
  11  *
  12  * This driver depends on the Intel integrated DMA controller (I/O AT).
  13  * If the driver for I/O AT (drivers/dma/ioatdma*) is also enabled,
  14  * this driver should work cooperatively.
  15  */
  16
  17 /* #define DEBUG */
  18
  19 #include <linux/module.h>
  20 #include <linux/pci.h>
  21 #include <linux/sched.h>
  22 #include <linux/notifier.h>
  23 #include <linux/cpumask.h>
  24 #include <linux/ktime.h>
  25 #include <linux/delay.h>
  26 #include <linux/debugfs.h>
  27 #include <linux/stop_machine.h>
  28 #include <linux/i7300_idle.h>
  29
  30 #include <asm/idle.h>
  31
  32 #include "../dma/ioatdma_hw.h"
  33 #include "../dma/ioatdma_registers.h"
  34
  35 #define I7300_IDLE_DRIVER_VERSION       "1.55"
  36 #define I7300_PRINT                     "i7300_idle:"
  37
  38 #define MAX_STOP_RETRIES        10
  39
  40 static int debug;
  41 module_param_named(debug, debug, uint, 0644);
  42 MODULE_PARM_DESC(debug, "Enable debug printks in this driver");
  43
  44 static int forceload;
  45 module_param_named(forceload, forceload, uint, 0644);
  46 MODULE_PARM_DESC(debug, "Enable driver testing on unvalidated i5000");
  47
  48 #define dprintk(fmt, arg...) \
  49         do { if (debug) printk(KERN_INFO I7300_PRINT fmt, ##arg); } while (0)
  50
  51 /*
  52  * Value to set THRTLOW to when initiating throttling
  53  *  0 = No throttling
  54  *  1 = Throttle when > 4 activations per eval window (Maximum throttling)
  55  *  2 = Throttle when > 8 activations
  56  *  168 = Throttle when > 672 activations (Minimum throttling)
  57  */
  58 #define MAX_THROTTLE_LOW_LIMIT          168
  59 static uint throttle_low_limit = 1;
  60 module_param_named(throttle_low_limit, throttle_low_limit, uint, 0644);
  61 MODULE_PARM_DESC(throttle_low_limit,
  62                 "Value for THRTLOWLM activation field "
  63                 "(0 = disable throttle, 1 = Max throttle, 168 = Min throttle)");
  64
  65 /*
  66  * simple invocation and duration statistics
  67  */
  68 static unsigned long total_starts;
  69 static unsigned long total_us;
  70
  71 #ifdef DEBUG
  72 static unsigned long past_skip;
  73 #endif
  74
  75 static struct pci_dev *fbd_dev;
  76
  77 static spinlock_t i7300_idle_lock;
  78 static int i7300_idle_active;
  79
  80 static u8 i7300_idle_thrtctl_saved;
  81 static u8 i7300_idle_thrtlow_saved;
  82 static u32 i7300_idle_mc_saved;
  83
  84 static cpumask_t idle_cpumask;
  85 static ktime_t start_ktime;
  86 static unsigned long avg_idle_us;
  87
  88 static struct dentry *debugfs_dir;
  89
  90 /* Begin: I/O AT Helper routines */
  91
  92 #define IOAT_CHANBASE(ioat_ctl, chan) (ioat_ctl + 0x80 + 0x80 * chan)
  93 /* Snoop control (disable snoops when coherency is not important) */
  94 #define IOAT_DESC_SADDR_SNP_CTL (1UL << 1)
  95 #define IOAT_DESC_DADDR_SNP_CTL (1UL << 2)
  96
  97 static struct pci_dev *ioat_dev;
  98 static struct ioat_dma_descriptor *ioat_desc; /* I/O AT desc & data (1 page) */
  99 static unsigned long ioat_desc_phys;
 100 static u8 *ioat_iomap; /* I/O AT memory-mapped control regs (aka CB_BAR) */
 101 static u8 *ioat_chanbase;
 102
 103 /* Start I/O AT memory copy */
 104 static int i7300_idle_ioat_start(void)
 105 {
 106         u32 err;
 107         /* Clear error (due to circular descriptor pointer) */
 108         err = readl(ioat_chanbase + IOAT_CHANERR_OFFSET);
 109         if (err)
 110                 writel(err, ioat_chanbase + IOAT_CHANERR_OFFSET);
 111
 112         writeb(IOAT_CHANCMD_START, ioat_chanbase + IOAT1_CHANCMD_OFFSET);
 113         return 0;
 114 }
 115
 116 /* Stop I/O AT memory copy */
 117 static void i7300_idle_ioat_stop(void)
 118 {
 119         int i;
 120         u64 sts;
 121
 122         for (i = 0; i < MAX_STOP_RETRIES; i++) {
 123                 writeb(IOAT_CHANCMD_RESET,
 124                         ioat_chanbase + IOAT1_CHANCMD_OFFSET);
 125
 126                 udelay(10);
 127
 128                 sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
 129                         IOAT_CHANSTS_DMA_TRANSFER_STATUS;
 130
 131                 if (sts != IOAT_CHANSTS_DMA_TRANSFER_STATUS_ACTIVE)
 132                         break;
 133
 134         }
 135
 136         if (i == MAX_STOP_RETRIES) {
 137                 dprintk("failed to stop I/O AT after %d retries\n",
 138                         MAX_STOP_RETRIES);
 139         }
 140 }
 141
 142 /* Test I/O AT by copying 1024 byte from 2k to 1k */
 143 static int __init i7300_idle_ioat_selftest(u8 *ctl,
 144                 struct ioat_dma_descriptor *desc, unsigned long desc_phys)
 145 {
 146         u64 chan_sts;
 147
 148         memset(desc, 0, 2048);
 149         memset((u8 *) desc + 2048, 0xab, 1024);
 150
 151         desc[0].size = 1024;
 152         desc[0].ctl = 0;
 153         desc[0].src_addr = desc_phys + 2048;
 154         desc[0].dst_addr = desc_phys + 1024;
 155         desc[0].next = 0;
 156
 157         writeb(IOAT_CHANCMD_RESET, ioat_chanbase + IOAT1_CHANCMD_OFFSET);
 158         writeb(IOAT_CHANCMD_START, ioat_chanbase + IOAT1_CHANCMD_OFFSET);
 159
 160         udelay(1000);
 161
 162         chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
 163                         IOAT_CHANSTS_DMA_TRANSFER_STATUS;
 164
 165         if (chan_sts != IOAT_CHANSTS_DMA_TRANSFER_STATUS_DONE) {
 166                 /* Not complete, reset the channel */
 167                 writeb(IOAT_CHANCMD_RESET,
 168                        ioat_chanbase + IOAT1_CHANCMD_OFFSET);
 169                 return -1;
 170         }
 171
 172         if (*(u32 *) ((u8 *) desc + 3068) != 0xabababab ||
 173             *(u32 *) ((u8 *) desc + 2044) != 0xabababab) {
 174                 dprintk("Data values src 0x%x, dest 0x%x, memset 0x%x\n",
 175                         *(u32 *) ((u8 *) desc + 2048),
 176                         *(u32 *) ((u8 *) desc + 1024),
 177                         *(u32 *) ((u8 *) desc + 3072));
 178                 return -1;
 179         }
 180         return 0;
 181 }
 182
 183 static struct device dummy_dma_dev = {
 184         .init_name = "fallback device",
 185         .coherent_dma_mask = DMA_BIT_MASK(64),
 186         .dma_mask = &dummy_dma_dev.coherent_dma_mask,
 187 };
 188
 189 /* Setup and initialize I/O AT */
 190 /* This driver needs I/O AT as the throttling takes effect only when there is
 191  * some memory activity. We use I/O AT to set up a dummy copy, while all CPUs
 192  * go idle and memory is throttled.
 193  */
 194 static int __init i7300_idle_ioat_init(void)
 195 {
 196         u8 ver, chan_count, ioat_chan;
 197         u16 chan_ctl;
 198
 199         ioat_iomap = (u8 *) ioremap_nocache(pci_resource_start(ioat_dev, 0),
 200                                             pci_resource_len(ioat_dev, 0));
 201
 202         if (!ioat_iomap) {
 203                 printk(KERN_ERR I7300_PRINT "failed to map I/O AT registers\n");
 204                 goto err_ret;
 205         }
 206
 207         ver = readb(ioat_iomap + IOAT_VER_OFFSET);
 208         if (ver != IOAT_VER_1_2) {
 209                 printk(KERN_ERR I7300_PRINT "unknown I/O AT version (%u.%u)\n",
 210                         ver >> 4, ver & 0xf);
 211                 goto err_unmap;
 212         }
 213
 214         chan_count = readb(ioat_iomap + IOAT_CHANCNT_OFFSET);
 215         if (!chan_count) {
 216                 printk(KERN_ERR I7300_PRINT "unexpected # of I/O AT channels "
 217                         "(%u)\n",
 218                         chan_count);
 219                 goto err_unmap;
 220         }
 221
 222         ioat_chan = chan_count - 1;
 223         ioat_chanbase = IOAT_CHANBASE(ioat_iomap, ioat_chan);
 224
 225         chan_ctl = readw(ioat_chanbase + IOAT_CHANCTRL_OFFSET);
 226         if (chan_ctl & IOAT_CHANCTRL_CHANNEL_IN_USE) {
 227                 printk(KERN_ERR I7300_PRINT "channel %d in use\n", ioat_chan);
 228                 goto err_unmap;
 229         }
 230
 231         writew(IOAT_CHANCTRL_CHANNEL_IN_USE,
 232                 ioat_chanbase + IOAT_CHANCTRL_OFFSET);
 233
 234         ioat_desc = (struct ioat_dma_descriptor *)dma_alloc_coherent(
 235                         &dummy_dma_dev, 4096,
 236                         (dma_addr_t *)&ioat_desc_phys, GFP_KERNEL);
 237         if (!ioat_desc) {
 238                 printk(KERN_ERR I7300_PRINT "failed to allocate I/O AT desc\n");
 239                 goto err_mark_unused;
 240         }
 241
 242         writel(ioat_desc_phys & 0xffffffffUL,
 243                ioat_chanbase + IOAT1_CHAINADDR_OFFSET_LOW);
 244         writel(ioat_desc_phys >> 32,
 245                ioat_chanbase + IOAT1_CHAINADDR_OFFSET_HIGH);
 246
 247         if (i7300_idle_ioat_selftest(ioat_iomap, ioat_desc, ioat_desc_phys)) {
 248                 printk(KERN_ERR I7300_PRINT "I/O AT self-test failed\n");
 249                 goto err_free;
 250         }
 251
 252         /* Setup circular I/O AT descriptor chain */
 253         ioat_desc[0].ctl = IOAT_DESC_SADDR_SNP_CTL | IOAT_DESC_DADDR_SNP_CTL;
 254         ioat_desc[0].src_addr = ioat_desc_phys + 2048;
 255         ioat_desc[0].dst_addr = ioat_desc_phys + 3072;
 256         ioat_desc[0].size = 128;
 257         ioat_desc[0].next = ioat_desc_phys + sizeof(struct ioat_dma_descriptor);
 258
 259         ioat_desc[1].ctl = ioat_desc[0].ctl;
 260         ioat_desc[1].src_addr = ioat_desc[0].src_addr;
 261         ioat_desc[1].dst_addr = ioat_desc[0].dst_addr;
 262         ioat_desc[1].size = ioat_desc[0].size;
 263         ioat_desc[1].next = ioat_desc_phys;
 264
 265         return 0;
 266
 267 err_free:
 268         dma_free_coherent(&dummy_dma_dev, 4096, (void *)ioat_desc, 0);
 269 err_mark_unused:
 270         writew(0, ioat_chanbase + IOAT_CHANCTRL_OFFSET);
 271 err_unmap:
 272         iounmap(ioat_iomap);
 273 err_ret:
 274         return -ENODEV;
 275 }
 276
 277 /* Cleanup I/O AT */
 278 static void __exit i7300_idle_ioat_exit(void)
 279 {
 280         int i;
 281         u64 chan_sts;
 282
 283         i7300_idle_ioat_stop();
 284
 285         /* Wait for a while for the channel to halt before releasing */
 286         for (i = 0; i < MAX_STOP_RETRIES; i++) {
 287                 writeb(IOAT_CHANCMD_RESET,
 288                        ioat_chanbase + IOAT1_CHANCMD_OFFSET);
 289
 290                 chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
 291                         IOAT_CHANSTS_DMA_TRANSFER_STATUS;
 292
 293                 if (chan_sts != IOAT_CHANSTS_DMA_TRANSFER_STATUS_ACTIVE) {
 294                         writew(0, ioat_chanbase + IOAT_CHANCTRL_OFFSET);
 295                         break;
 296                 }
 297                 udelay(1000);
 298         }
 299
 300         chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
 301                         IOAT_CHANSTS_DMA_TRANSFER_STATUS;
 302
 303         /*
 304          * We tried to reset multiple times. If IO A/T channel is still active
 305          * flag an error and return without cleanup. Memory leak is better
 306          * than random corruption in that extreme error situation.
 307          */
 308         if (chan_sts == IOAT_CHANSTS_DMA_TRANSFER_STATUS_ACTIVE) {
 309                 printk(KERN_ERR I7300_PRINT "Unable to stop IO A/T channels."
 310                         " Not freeing resources\n");
 311                 return;
 312         }
 313
 314         dma_free_coherent(&dummy_dma_dev, 4096, (void *)ioat_desc, 0);
 315         iounmap(ioat_iomap);
 316 }
 317
 318 /* End: I/O AT Helper routines */
 319
 320 #define DIMM_THRTLOW 0x64
 321 #define DIMM_THRTCTL 0x67
 322 #define DIMM_THRTCTL_THRMHUNT (1UL << 0)
 323 #define DIMM_MC 0x40
 324 #define DIMM_GTW_MODE (1UL << 17)
 325 #define DIMM_GBLACT 0x60
 326
 327 /*
 328  * Keep track of an exponential-decaying average of recent idle durations.
 329  * The latest duration gets DURATION_WEIGHT_PCT percentage weight
 330  * in this average, with the old average getting the remaining weight.
 331  *
 332  * High weights emphasize recent history, low weights include long history.
 333  */
 334 #define DURATION_WEIGHT_PCT 55
 335
 336 /*
 337  * When the decaying average of recent durations or the predicted duration
 338  * of the next timer interrupt is shorter than duration_threshold, the
 339  * driver will decline to throttle.
 340  */
 341 #define DURATION_THRESHOLD_US 100
 342
 343
 344 /* Store DIMM thermal throttle configuration */
 345 static int i7300_idle_thrt_save(void)
 346 {
 347         u32 new_mc_val;
 348         u8 gblactlm;
 349
 350         pci_read_config_byte(fbd_dev, DIMM_THRTCTL, &i7300_idle_thrtctl_saved);
 351         pci_read_config_byte(fbd_dev, DIMM_THRTLOW, &i7300_idle_thrtlow_saved);
 352         pci_read_config_dword(fbd_dev, DIMM_MC, &i7300_idle_mc_saved);
 353         /*
 354          * Make sure we have Global Throttling Window Mode set to have a
 355          * "short" window. This (mostly) works around an issue where
 356          * throttling persists until the end of the global throttling window
 357          * size. On the tested system, this was resulting in a maximum of
 358          * 64 ms to exit throttling (average 32 ms). The actual numbers
 359          * depends on system frequencies. Setting the short window reduces
 360          * this by a factor of 4096.
 361          *
 362          * We will only do this only if the system is set for
 363          * unlimited-activations while in open-loop throttling (i.e., when
 364          * Global Activation Throttle Limit is zero).
 365          */
 366         pci_read_config_byte(fbd_dev, DIMM_GBLACT, &gblactlm);
 367         dprintk("thrtctl_saved = 0x%02x, thrtlow_saved = 0x%02x\n",
 368                 i7300_idle_thrtctl_saved,
 369                 i7300_idle_thrtlow_saved);
 370         dprintk("mc_saved = 0x%08x, gblactlm = 0x%02x\n",
 371                 i7300_idle_mc_saved,
 372                 gblactlm);
 373         if (gblactlm == 0) {
 374                 new_mc_val = i7300_idle_mc_saved | DIMM_GTW_MODE;
 375                 pci_write_config_dword(fbd_dev, DIMM_MC, new_mc_val);
 376                 return 0;
 377         } else {
 378                 dprintk("could not set GTW_MODE = 1 (OLTT enabled)\n");
 379                 return -ENODEV;
 380         }
 381 }
 382
 383 /* Restore DIMM thermal throttle configuration */
 384 static void i7300_idle_thrt_restore(void)
 385 {
 386         pci_write_config_dword(fbd_dev, DIMM_MC, i7300_idle_mc_saved);
 387         pci_write_config_byte(fbd_dev, DIMM_THRTLOW, i7300_idle_thrtlow_saved);
 388         pci_write_config_byte(fbd_dev, DIMM_THRTCTL, i7300_idle_thrtctl_saved);
 389 }
 390
 391 /* Enable DIMM thermal throttling */
 392 static void i7300_idle_start(void)
 393 {
 394         u8 new_ctl;
 395         u8 limit;
 396
 397         new_ctl = i7300_idle_thrtctl_saved & ~DIMM_THRTCTL_THRMHUNT;
 398         pci_write_config_byte(fbd_dev, DIMM_THRTCTL, new_ctl);
 399
 400         limit = throttle_low_limit;
 401         if (unlikely(limit > MAX_THROTTLE_LOW_LIMIT))
 402                 limit = MAX_THROTTLE_LOW_LIMIT;
 403
 404         pci_write_config_byte(fbd_dev, DIMM_THRTLOW, limit);
 405
 406         new_ctl = i7300_idle_thrtctl_saved | DIMM_THRTCTL_THRMHUNT;
 407         pci_write_config_byte(fbd_dev, DIMM_THRTCTL, new_ctl);
 408 }
 409
 410 /* Disable DIMM thermal throttling */
 411 static void i7300_idle_stop(void)
 412 {
 413         u8 new_ctl;
 414         u8 got_ctl;
 415
 416         new_ctl = i7300_idle_thrtctl_saved & ~DIMM_THRTCTL_THRMHUNT;
 417         pci_write_config_byte(fbd_dev, DIMM_THRTCTL, new_ctl);
 418
 419         pci_write_config_byte(fbd_dev, DIMM_THRTLOW, i7300_idle_thrtlow_saved);
 420         pci_write_config_byte(fbd_dev, DIMM_THRTCTL, i7300_idle_thrtctl_saved);
 421         pci_read_config_byte(fbd_dev, DIMM_THRTCTL, &got_ctl);
 422         WARN_ON_ONCE(got_ctl != i7300_idle_thrtctl_saved);
 423 }
 424
 425
 426 /*
 427  * i7300_avg_duration_check()
 428  * return 0 if the decaying average of recent idle durations is
 429  * more than DURATION_THRESHOLD_US
 430  */
 431 static int i7300_avg_duration_check(void)
 432 {
 433         if (avg_idle_us >= DURATION_THRESHOLD_US)
 434                 return 0;
 435
 436 #ifdef DEBUG
 437         past_skip++;
 438 #endif
 439         return 1;
 440 }
 441
 442 /* Idle notifier to look at idle CPUs */
 443 static int i7300_idle_notifier(struct notifier_block *nb, unsigned long val,
 444                                 void *data)
 445 {
 446         unsigned long flags;
 447         ktime_t now_ktime;
 448         static ktime_t idle_begin_time;
 449         static int time_init = 1;
 450
 451         if (!throttle_low_limit)
 452                 return 0;
 453
 454         if (unlikely(time_init)) {
 455                 time_init = 0;
 456                 idle_begin_time = ktime_get();
 457         }
 458
 459         spin_lock_irqsave(&i7300_idle_lock, flags);
 460         if (val == IDLE_START) {
 461
 462                 cpu_set(smp_processor_id(), idle_cpumask);
 463
 464                 if (cpus_weight(idle_cpumask) != num_online_cpus())
 465                         goto end;
 466
 467                 now_ktime = ktime_get();
 468                 idle_begin_time = now_ktime;
 469
 470                 if (i7300_avg_duration_check())
 471                         goto end;
 472
 473                 i7300_idle_active = 1;
 474                 total_starts++;
 475                 start_ktime = now_ktime;
 476
 477                 i7300_idle_start();
 478                 i7300_idle_ioat_start();
 479
 480         } else if (val == IDLE_END) {
 481                 cpu_clear(smp_processor_id(), idle_cpumask);
 482                 if (cpus_weight(idle_cpumask) == (num_online_cpus() - 1)) {
 483                         /* First CPU coming out of idle */
 484                         u64 idle_duration_us;
 485
 486                         now_ktime = ktime_get();
 487
 488                         idle_duration_us = ktime_to_us(ktime_sub
 489                                                 (now_ktime, idle_begin_time));
 490
 491                         avg_idle_us =
 492                                 ((100 - DURATION_WEIGHT_PCT) * avg_idle_us +
 493                                  DURATION_WEIGHT_PCT * idle_duration_us) / 100;
 494
 495                         if (i7300_idle_active) {
 496                                 ktime_t idle_ktime;
 497
 498                                 idle_ktime = ktime_sub(now_ktime, start_ktime);
 499                                 total_us += ktime_to_us(idle_ktime);
 500
 501                                 i7300_idle_ioat_stop();
 502                                 i7300_idle_stop();
 503                                 i7300_idle_active = 0;
 504                         }
 505                 }
 506         }
 507 end:
 508         spin_unlock_irqrestore(&i7300_idle_lock, flags);
 509         return 0;
 510 }
 511
 512 static struct notifier_block i7300_idle_nb = {
 513         .notifier_call = i7300_idle_notifier,
 514 };
 515
 516 MODULE_DEVICE_TABLE(pci, pci_tbl);
 517
 518 int stats_open_generic(struct inode *inode, struct file *fp)
 519 {
 520         fp->private_data = inode->i_private;
 521         return 0;
 522 }
 523
 524 static ssize_t stats_read_ul(struct file *fp, char __user *ubuf, size_t count,
 525                                 loff_t *off)
 526 {
 527         unsigned long *p = fp->private_data;
 528         char buf[32];
 529         int len;
 530
 531         len = snprintf(buf, 32, "%lu\n", *p);
 532         return simple_read_from_buffer(ubuf, count, off, buf, len);
 533 }
 534
 535 static const struct file_operations idle_fops = {
 536         .open   = stats_open_generic,
 537         .read   = stats_read_ul,
 538 };
 539
 540 struct debugfs_file_info {
 541         void *ptr;
 542         char name[32];
 543         struct dentry *file;
 544 } debugfs_file_list[] = {
 545                                 {&total_starts, "total_starts", NULL},
 546                                 {&total_us, "total_us", NULL},
 547 #ifdef DEBUG
 548                                 {&past_skip, "past_skip", NULL},
 549 #endif
 550                                 {NULL, "", NULL}
 551                         };
 552
 553 static int __init i7300_idle_init(void)
 554 {
 555         spin_lock_init(&i7300_idle_lock);
 556         cpus_clear(idle_cpumask);
 557         total_us = 0;
 558
 559         if (i7300_idle_platform_probe(&fbd_dev, &ioat_dev, forceload))
 560                 return -ENODEV;
 561
 562         if (i7300_idle_thrt_save())
 563                 return -ENODEV;
 564
 565         if (i7300_idle_ioat_init())
 566                 return -ENODEV;
 567
 568         debugfs_dir = debugfs_create_dir("i7300_idle", NULL);
 569         if (debugfs_dir) {
 570                 int i = 0;
 571
 572                 while (debugfs_file_list[i].ptr != NULL) {
 573                         debugfs_file_list[i].file = debugfs_create_file(
 574                                         debugfs_file_list[i].name,
 575                                         S_IRUSR,
 576                                         debugfs_dir,
 577                                         debugfs_file_list[i].ptr,
 578                                         &idle_fops);
 579                         i++;
 580                 }
 581         }
 582
 583         idle_notifier_register(&i7300_idle_nb);
 584
 585         printk(KERN_INFO "i7300_idle: loaded v%s\n", I7300_IDLE_DRIVER_VERSION);
 586         return 0;
 587 }
 588
 589 static void __exit i7300_idle_exit(void)
 590 {
 591         idle_notifier_unregister(&i7300_idle_nb);
 592
 593         if (debugfs_dir) {
 594                 int i = 0;
 595
 596                 while (debugfs_file_list[i].file != NULL) {
 597                         debugfs_remove(debugfs_file_list[i].file);
 598                         i++;
 599                 }
 600
 601                 debugfs_remove(debugfs_dir);
 602         }
 603         i7300_idle_thrt_restore();
 604         i7300_idle_ioat_exit();
 605 }
 606
 607 module_init(i7300_idle_init);
 608 module_exit(i7300_idle_exit);
 609
 610 MODULE_AUTHOR("Andy Henroid <andrew.d.henroid@intel.com>");
 611 MODULE_DESCRIPTION("Intel Chipset DIMM Idle Power Saving Driver v"
 612                         I7300_IDLE_DRIVER_VERSION);
 613 MODULE_LICENSE("GPL");