drivers/macintosh/rack-meter.c

   1 /*
   2  * RackMac vu-meter driver
   3  *
   4  * (c) Copyright 2006 Benjamin Herrenschmidt, IBM Corp.
   5  *                    <benh@kernel.crashing.org>
   6  *
   7  * Released under the term of the GNU GPL v2.
   8  *
   9  * Support the CPU-meter LEDs of the Xserve G5
  10  *
  11  * TODO: Implement PWM to do variable intensity and provide userland
  12  * interface for fun. Also, the CPU-meter could be made nicer by being
  13  * a bit less "immediate" but giving instead a more average load over
  14  * time. Patches welcome :-)
  15  *
  16  */
  17 #undef DEBUG
  18
  19 #include <linux/types.h>
  20 #include <linux/kernel.h>
  21 #include <linux/slab.h>
  22 #include <linux/device.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/module.h>
  25 #include <linux/pci.h>
  26 #include <linux/dma-mapping.h>
  27 #include <linux/kernel_stat.h>
  28 #include <linux/of_address.h>
  29 #include <linux/of_irq.h>
  30
  31 #include <asm/io.h>
  32 #include <asm/prom.h>
  33 #include <asm/machdep.h>
  34 #include <asm/pmac_feature.h>
  35 #include <asm/dbdma.h>
  36 #include <asm/macio.h>
  37 #include <asm/keylargo.h>
  38
  39 /* Number of samples in a sample buffer */
  40 #define SAMPLE_COUNT            256
  41
  42 /* CPU meter sampling rate in ms */
  43 #define CPU_SAMPLING_RATE       250
  44
  45 struct rackmeter_dma {
  46         struct dbdma_cmd        cmd[4]                  ____cacheline_aligned;
  47         u32                     mark                    ____cacheline_aligned;
  48         u32                     buf1[SAMPLE_COUNT]      ____cacheline_aligned;
  49         u32                     buf2[SAMPLE_COUNT]      ____cacheline_aligned;
  50 } ____cacheline_aligned;
  51
  52 struct rackmeter_cpu {
  53         struct delayed_work     sniffer;
  54         struct rackmeter        *rm;
  55         cputime64_t             prev_wall;
  56         cputime64_t             prev_idle;
  57         int                     zero;
  58 } ____cacheline_aligned;
  59
  60 struct rackmeter {
  61         struct macio_dev                *mdev;
  62         unsigned int                    irq;
  63         struct device_node              *i2s;
  64         u8                              *ubuf;
  65         struct dbdma_regs __iomem       *dma_regs;
  66         void __iomem                    *i2s_regs;
  67         dma_addr_t                      dma_buf_p;
  68         struct rackmeter_dma            *dma_buf_v;
  69         int                             stale_irq;
  70         struct rackmeter_cpu            cpu[2];
  71         int                             paused;
  72         struct mutex                    sem;
  73 };
  74
  75 /* To be set as a tunable */
  76 static int rackmeter_ignore_nice;
  77
  78 /* This GPIO is whacked by the OS X driver when initializing */
  79 #define RACKMETER_MAGIC_GPIO    0x78
  80
  81 /* This is copied from cpufreq_ondemand, maybe we should put it in
  82  * a common header somewhere
  83  */
  84 static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
  85 {
  86         u64 retval;
  87
  88         retval = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE] +
  89                  kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT];
  90
  91         if (rackmeter_ignore_nice)
  92                 retval += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
  93
  94         return retval;
  95 }
  96
  97 static void rackmeter_setup_i2s(struct rackmeter *rm)
  98 {
  99         struct macio_chip *macio = rm->mdev->bus->chip;
 100
 101         /* First whack magic GPIO */
 102         pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, RACKMETER_MAGIC_GPIO, 5);
 103
 104
 105         /* Call feature code to enable the sound channel and the proper
 106          * clock sources
 107          */
 108         pmac_call_feature(PMAC_FTR_SOUND_CHIP_ENABLE, rm->i2s, 0, 1);
 109
 110         /* Power i2s and stop i2s clock. We whack MacIO FCRs directly for now.
 111          * This is a bit racy, thus we should add new platform functions to
 112          * handle that. snd-aoa needs that too
 113          */
 114         MACIO_BIS(KEYLARGO_FCR1, KL1_I2S0_ENABLE);
 115         MACIO_BIC(KEYLARGO_FCR1, KL1_I2S0_CLK_ENABLE_BIT);
 116         (void)MACIO_IN32(KEYLARGO_FCR1);
 117         udelay(10);
 118
 119         /* Then setup i2s. For now, we use the same magic value that
 120          * the OS X driver seems to use. We might want to play around
 121          * with the clock divisors later
 122          */
 123         out_le32(rm->i2s_regs + 0x10, 0x01fa0000);
 124         (void)in_le32(rm->i2s_regs + 0x10);
 125         udelay(10);
 126
 127         /* Fully restart i2s*/
 128         MACIO_BIS(KEYLARGO_FCR1, KL1_I2S0_CELL_ENABLE |
 129                   KL1_I2S0_CLK_ENABLE_BIT);
 130         (void)MACIO_IN32(KEYLARGO_FCR1);
 131         udelay(10);
 132 }
 133
 134 static void rackmeter_set_default_pattern(struct rackmeter *rm)
 135 {
 136         int i;
 137
 138         for (i = 0; i < 16; i++) {
 139                 if (i < 8)
 140                         rm->ubuf[i] = (i & 1) * 255;
 141                 else
 142                         rm->ubuf[i] = ((~i) & 1) * 255;
 143         }
 144 }
 145
 146 static void rackmeter_do_pause(struct rackmeter *rm, int pause)
 147 {
 148         struct rackmeter_dma *rdma = rm->dma_buf_v;
 149
 150         pr_debug("rackmeter: %s\n", pause ? "paused" : "started");
 151
 152         rm->paused = pause;
 153         if (pause) {
 154                 DBDMA_DO_STOP(rm->dma_regs);
 155                 return;
 156         }
 157         memset(rdma->buf1, 0, SAMPLE_COUNT & sizeof(u32));
 158         memset(rdma->buf2, 0, SAMPLE_COUNT & sizeof(u32));
 159
 160         rm->dma_buf_v->mark = 0;
 161
 162         mb();
 163         out_le32(&rm->dma_regs->cmdptr_hi, 0);
 164         out_le32(&rm->dma_regs->cmdptr, rm->dma_buf_p);
 165         out_le32(&rm->dma_regs->control, (RUN << 16) | RUN);
 166 }
 167
 168 static void rackmeter_setup_dbdma(struct rackmeter *rm)
 169 {
 170         struct rackmeter_dma *db = rm->dma_buf_v;
 171         struct dbdma_cmd *cmd = db->cmd;
 172
 173         /* Make sure dbdma is reset */
 174         DBDMA_DO_RESET(rm->dma_regs);
 175
 176         pr_debug("rackmeter: mark offset=0x%zx\n",
 177                  offsetof(struct rackmeter_dma, mark));
 178         pr_debug("rackmeter: buf1 offset=0x%zx\n",
 179                  offsetof(struct rackmeter_dma, buf1));
 180         pr_debug("rackmeter: buf2 offset=0x%zx\n",
 181                  offsetof(struct rackmeter_dma, buf2));
 182
 183         /* Prepare 4 dbdma commands for the 2 buffers */
 184         memset(cmd, 0, 4 * sizeof(struct dbdma_cmd));
 185         cmd->req_count = cpu_to_le16(4);
 186         cmd->command = cpu_to_le16(STORE_WORD | INTR_ALWAYS | KEY_SYSTEM);
 187         cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
 188                 offsetof(struct rackmeter_dma, mark));
 189         cmd->cmd_dep = cpu_to_le32(0x02000000);
 190         cmd++;
 191
 192         cmd->req_count = cpu_to_le16(SAMPLE_COUNT * 4);
 193         cmd->command = cpu_to_le16(OUTPUT_MORE);
 194         cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
 195                 offsetof(struct rackmeter_dma, buf1));
 196         cmd++;
 197
 198         cmd->req_count = cpu_to_le16(4);
 199         cmd->command = cpu_to_le16(STORE_WORD | INTR_ALWAYS | KEY_SYSTEM);
 200         cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
 201                 offsetof(struct rackmeter_dma, mark));
 202         cmd->cmd_dep = cpu_to_le32(0x01000000);
 203         cmd++;
 204
 205         cmd->req_count = cpu_to_le16(SAMPLE_COUNT * 4);
 206         cmd->command = cpu_to_le16(OUTPUT_MORE | BR_ALWAYS);
 207         cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
 208                 offsetof(struct rackmeter_dma, buf2));
 209         cmd->cmd_dep = cpu_to_le32(rm->dma_buf_p);
 210
 211         rackmeter_do_pause(rm, 0);
 212 }
 213
 214 static void rackmeter_do_timer(struct work_struct *work)
 215 {
 216         struct rackmeter_cpu *rcpu =
 217                 container_of(work, struct rackmeter_cpu, sniffer.work);
 218         struct rackmeter *rm = rcpu->rm;
 219         unsigned int cpu = smp_processor_id();
 220         cputime64_t cur_jiffies, total_idle_ticks;
 221         unsigned int total_ticks, idle_ticks;
 222         int i, offset, load, cumm, pause;
 223
 224         cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
 225         total_ticks = (unsigned int) (cur_jiffies - rcpu->prev_wall);
 226         rcpu->prev_wall = cur_jiffies;
 227
 228         total_idle_ticks = get_cpu_idle_time(cpu);
 229         idle_ticks = (unsigned int) (total_idle_ticks - rcpu->prev_idle);
 230         rcpu->prev_idle = total_idle_ticks;
 231
 232         /* We do a very dumb calculation to update the LEDs for now,
 233          * we'll do better once we have actual PWM implemented
 234          */
 235         load = (9 * (total_ticks - idle_ticks)) / total_ticks;
 236
 237         offset = cpu << 3;
 238         cumm = 0;
 239         for (i = 0; i < 8; i++) {
 240                 u8 ub = (load > i) ? 0xff : 0;
 241                 rm->ubuf[i + offset] = ub;
 242                 cumm |= ub;
 243         }
 244         rcpu->zero = (cumm == 0);
 245
 246         /* Now check if LEDs are all 0, we can stop DMA */
 247         pause = (rm->cpu[0].zero && rm->cpu[1].zero);
 248         if (pause != rm->paused) {
 249                 mutex_lock(&rm->sem);
 250                 pause = (rm->cpu[0].zero && rm->cpu[1].zero);
 251                 rackmeter_do_pause(rm, pause);
 252                 mutex_unlock(&rm->sem);
 253         }
 254         schedule_delayed_work_on(cpu, &rcpu->sniffer,
 255                                  msecs_to_jiffies(CPU_SAMPLING_RATE));
 256 }
 257
 258 static void rackmeter_init_cpu_sniffer(struct rackmeter *rm)
 259 {
 260         unsigned int cpu;
 261
 262         /* This driver works only with 1 or 2 CPUs numbered 0 and 1,
 263          * but that's really all we have on Apple Xserve. It doesn't
 264          * play very nice with CPU hotplug neither but we don't do that
 265          * on those machines yet
 266          */
 267
 268         rm->cpu[0].rm = rm;
 269         INIT_DELAYED_WORK(&rm->cpu[0].sniffer, rackmeter_do_timer);
 270         rm->cpu[1].rm = rm;
 271         INIT_DELAYED_WORK(&rm->cpu[1].sniffer, rackmeter_do_timer);
 272
 273         for_each_online_cpu(cpu) {
 274                 struct rackmeter_cpu *rcpu;
 275
 276                 if (cpu > 1)
 277                         continue;
 278                 rcpu = &rm->cpu[cpu];
 279                 rcpu->prev_idle = get_cpu_idle_time(cpu);
 280                 rcpu->prev_wall = jiffies64_to_cputime64(get_jiffies_64());
 281                 schedule_delayed_work_on(cpu, &rm->cpu[cpu].sniffer,
 282                                          msecs_to_jiffies(CPU_SAMPLING_RATE));
 283         }
 284 }
 285
 286 static void rackmeter_stop_cpu_sniffer(struct rackmeter *rm)
 287 {
 288         cancel_delayed_work_sync(&rm->cpu[0].sniffer);
 289         cancel_delayed_work_sync(&rm->cpu[1].sniffer);
 290 }
 291
 292 static int rackmeter_setup(struct rackmeter *rm)
 293 {
 294         pr_debug("rackmeter: setting up i2s..\n");
 295         rackmeter_setup_i2s(rm);
 296
 297         pr_debug("rackmeter: setting up default pattern..\n");
 298         rackmeter_set_default_pattern(rm);
 299
 300         pr_debug("rackmeter: setting up dbdma..\n");
 301         rackmeter_setup_dbdma(rm);
 302
 303         pr_debug("rackmeter: start CPU measurements..\n");
 304         rackmeter_init_cpu_sniffer(rm);
 305
 306         printk(KERN_INFO "RackMeter initialized\n");
 307
 308         return 0;
 309 }
 310
 311 /*  XXX FIXME: No PWM yet, this is 0/1 */
 312 static u32 rackmeter_calc_sample(struct rackmeter *rm, unsigned int index)
 313 {
 314         int led;
 315         u32 sample = 0;
 316
 317         for (led = 0; led < 16; led++) {
 318                 sample >>= 1;
 319                 sample |= ((rm->ubuf[led] >= 0x80) << 15);
 320         }
 321         return (sample << 17) | (sample >> 15);
 322 }
 323
 324 static irqreturn_t rackmeter_irq(int irq, void *arg)
 325 {
 326         struct rackmeter *rm = arg;
 327         struct rackmeter_dma *db = rm->dma_buf_v;
 328         unsigned int mark, i;
 329         u32 *buf;
 330
 331         /* Flush PCI buffers with an MMIO read. Maybe we could actually
 332          * check the status one day ... in case things go wrong, though
 333          * this never happened to me
 334          */
 335         (void)in_le32(&rm->dma_regs->status);
 336
 337         /* Make sure the CPU gets us in order */
 338         rmb();
 339
 340         /* Read mark */
 341         mark = db->mark;
 342         if (mark != 1 && mark != 2) {
 343                 printk(KERN_WARNING "rackmeter: Incorrect DMA mark 0x%08x\n",
 344                        mark);
 345                 /* We allow for 3 errors like that (stale DBDMA irqs) */
 346                 if (++rm->stale_irq > 3) {
 347                         printk(KERN_ERR "rackmeter: Too many errors,"
 348                                " stopping DMA\n");
 349                         DBDMA_DO_RESET(rm->dma_regs);
 350                 }
 351                 return IRQ_HANDLED;
 352         }
 353
 354         /* Next buffer we need to fill is mark value */
 355         buf = mark == 1 ? db->buf1 : db->buf2;
 356
 357         /* Fill it now. This routine converts the 8 bits depth sample array
 358          * into the PWM bitmap for each LED.
 359          */
 360         for (i = 0; i < SAMPLE_COUNT; i++)
 361                 buf[i] = rackmeter_calc_sample(rm, i);
 362
 363
 364         return IRQ_HANDLED;
 365 }
 366
 367 static int rackmeter_probe(struct macio_dev* mdev,
 368                            const struct of_device_id *match)
 369 {
 370         struct device_node *i2s = NULL, *np = NULL;
 371         struct rackmeter *rm = NULL;
 372         struct resource ri2s, rdma;
 373         int rc = -ENODEV;
 374
 375         pr_debug("rackmeter_probe()\n");
 376
 377         /* Get i2s-a node */
 378         while ((i2s = of_get_next_child(mdev->ofdev.dev.of_node, i2s)) != NULL)
 379                if (strcmp(i2s->name, "i2s-a") == 0)
 380                        break;
 381         if (i2s == NULL) {
 382                 pr_debug("  i2s-a child not found\n");
 383                 goto bail;
 384         }
 385         /* Get lightshow or virtual sound */
 386         while ((np = of_get_next_child(i2s, np)) != NULL) {
 387                if (strcmp(np->name, "lightshow") == 0)
 388                        break;
 389                if ((strcmp(np->name, "sound") == 0) &&
 390                    of_get_property(np, "virtual", NULL) != NULL)
 391                        break;
 392         }
 393         if (np == NULL) {
 394                 pr_debug("  lightshow or sound+virtual child not found\n");
 395                 goto bail;
 396         }
 397
 398         /* Create and initialize our instance data */
 399         rm = kzalloc(sizeof(struct rackmeter), GFP_KERNEL);
 400         if (rm == NULL) {
 401                 printk(KERN_ERR "rackmeter: failed to allocate memory !\n");
 402                 rc = -ENOMEM;
 403                 goto bail_release;
 404         }
 405         rm->mdev = mdev;
 406         rm->i2s = i2s;
 407         mutex_init(&rm->sem);
 408         dev_set_drvdata(&mdev->ofdev.dev, rm);
 409         /* Check resources availability. We need at least resource 0 and 1 */
 410 #if 0 /* Use that when i2s-a is finally an mdev per-se */
 411         if (macio_resource_count(mdev) < 2 || macio_irq_count(mdev) < 2) {
 412                 printk(KERN_ERR
 413                        "rackmeter: found match but lacks resources: %s"
 414                        " (%d resources, %d interrupts)\n",
 415                        mdev->ofdev.node->full_name);
 416                 rc = -ENXIO;
 417                 goto bail_free;
 418         }
 419         if (macio_request_resources(mdev, "rackmeter")) {
 420                 printk(KERN_ERR
 421                        "rackmeter: failed to request resources: %s\n",
 422                        mdev->ofdev.node->full_name);
 423                 rc = -EBUSY;
 424                 goto bail_free;
 425         }
 426         rm->irq = macio_irq(mdev, 1);
 427 #else
 428         rm->irq = irq_of_parse_and_map(i2s, 1);
 429         if (rm->irq == NO_IRQ ||
 430             of_address_to_resource(i2s, 0, &ri2s) ||
 431             of_address_to_resource(i2s, 1, &rdma)) {
 432                 printk(KERN_ERR
 433                        "rackmeter: found match but lacks resources: %s",
 434                        mdev->ofdev.dev.of_node->full_name);
 435                 rc = -ENXIO;
 436                 goto bail_free;
 437         }
 438 #endif
 439
 440         pr_debug("  i2s @0x%08x\n", (unsigned int)ri2s.start);
 441         pr_debug("  dma @0x%08x\n", (unsigned int)rdma.start);
 442         pr_debug("  irq %d\n", rm->irq);
 443
 444         rm->ubuf = (u8 *)__get_free_page(GFP_KERNEL);
 445         if (rm->ubuf == NULL) {
 446                 printk(KERN_ERR
 447                        "rackmeter: failed to allocate samples page !\n");
 448                 rc = -ENOMEM;
 449                 goto bail_release;
 450         }
 451
 452         rm->dma_buf_v = dma_alloc_coherent(&macio_get_pci_dev(mdev)->dev,
 453                                            sizeof(struct rackmeter_dma),
 454                                            &rm->dma_buf_p, GFP_KERNEL);
 455         if (rm->dma_buf_v == NULL) {
 456                 printk(KERN_ERR
 457                        "rackmeter: failed to allocate dma buffer !\n");
 458                 rc = -ENOMEM;
 459                 goto bail_free_samples;
 460         }
 461 #if 0
 462         rm->i2s_regs = ioremap(macio_resource_start(mdev, 0), 0x1000);
 463 #else
 464         rm->i2s_regs = ioremap(ri2s.start, 0x1000);
 465 #endif
 466         if (rm->i2s_regs == NULL) {
 467                 printk(KERN_ERR
 468                        "rackmeter: failed to map i2s registers !\n");
 469                 rc = -ENXIO;
 470                 goto bail_free_dma;
 471         }
 472 #if 0
 473         rm->dma_regs = ioremap(macio_resource_start(mdev, 1), 0x100);
 474 #else
 475         rm->dma_regs = ioremap(rdma.start, 0x100);
 476 #endif
 477         if (rm->dma_regs == NULL) {
 478                 printk(KERN_ERR
 479                        "rackmeter: failed to map dma registers !\n");
 480                 rc = -ENXIO;
 481                 goto bail_unmap_i2s;
 482         }
 483
 484         rc = rackmeter_setup(rm);
 485         if (rc) {
 486                 printk(KERN_ERR
 487                        "rackmeter: failed to initialize !\n");
 488                 rc = -ENXIO;
 489                 goto bail_unmap_dma;
 490         }
 491
 492         rc = request_irq(rm->irq, rackmeter_irq, 0, "rackmeter", rm);
 493         if (rc != 0) {
 494                 printk(KERN_ERR
 495                        "rackmeter: failed to request interrupt !\n");
 496                 goto bail_stop_dma;
 497         }
 498         of_node_put(np);
 499         return 0;
 500
 501  bail_stop_dma:
 502         DBDMA_DO_RESET(rm->dma_regs);
 503  bail_unmap_dma:
 504         iounmap(rm->dma_regs);
 505  bail_unmap_i2s:
 506         iounmap(rm->i2s_regs);
 507  bail_free_dma:
 508         dma_free_coherent(&macio_get_pci_dev(mdev)->dev,
 509                           sizeof(struct rackmeter_dma),
 510                           rm->dma_buf_v, rm->dma_buf_p);
 511  bail_free_samples:
 512         free_page((unsigned long)rm->ubuf);
 513  bail_release:
 514 #if 0
 515         macio_release_resources(mdev);
 516 #endif
 517  bail_free:
 518         kfree(rm);
 519  bail:
 520         of_node_put(i2s);
 521         of_node_put(np);
 522         dev_set_drvdata(&mdev->ofdev.dev, NULL);
 523         return rc;
 524 }
 525
 526 static int rackmeter_remove(struct macio_dev* mdev)
 527 {
 528         struct rackmeter *rm = dev_get_drvdata(&mdev->ofdev.dev);
 529
 530         /* Stop CPU sniffer timer & work queues */
 531         rackmeter_stop_cpu_sniffer(rm);
 532
 533         /* Clear reference to private data */
 534         dev_set_drvdata(&mdev->ofdev.dev, NULL);
 535
 536         /* Stop/reset dbdma */
 537         DBDMA_DO_RESET(rm->dma_regs);
 538
 539         /* Release the IRQ */
 540         free_irq(rm->irq, rm);
 541
 542         /* Unmap registers */
 543         iounmap(rm->dma_regs);
 544         iounmap(rm->i2s_regs);
 545
 546         /* Free DMA */
 547         dma_free_coherent(&macio_get_pci_dev(mdev)->dev,
 548                           sizeof(struct rackmeter_dma),
 549                           rm->dma_buf_v, rm->dma_buf_p);
 550
 551         /* Free samples */
 552         free_page((unsigned long)rm->ubuf);
 553
 554 #if 0
 555         /* Release resources */
 556         macio_release_resources(mdev);
 557 #endif
 558
 559         /* Get rid of me */
 560         kfree(rm);
 561
 562         return 0;
 563 }
 564
 565 static int rackmeter_shutdown(struct macio_dev* mdev)
 566 {
 567         struct rackmeter *rm = dev_get_drvdata(&mdev->ofdev.dev);
 568
 569         if (rm == NULL)
 570                 return -ENODEV;
 571
 572         /* Stop CPU sniffer timer & work queues */
 573         rackmeter_stop_cpu_sniffer(rm);
 574
 575         /* Stop/reset dbdma */
 576         DBDMA_DO_RESET(rm->dma_regs);
 577
 578         return 0;
 579 }
 580
 581 static struct of_device_id rackmeter_match[] = {
 582         { .name = "i2s" },
 583         { }
 584 };
 585
 586 static struct macio_driver rackmeter_driver = {
 587         .driver = {
 588                 .name = "rackmeter",
 589                 .owner = THIS_MODULE,
 590                 .of_match_table = rackmeter_match,
 591         },
 592         .probe = rackmeter_probe,
 593         .remove = rackmeter_remove,
 594         .shutdown = rackmeter_shutdown,
 595 };
 596
 597
 598 static int __init rackmeter_init(void)
 599 {
 600         pr_debug("rackmeter_init()\n");
 601
 602         return macio_register_driver(&rackmeter_driver);
 603 }
 604
 605 static void __exit rackmeter_exit(void)
 606 {
 607         pr_debug("rackmeter_exit()\n");
 608
 609         macio_unregister_driver(&rackmeter_driver);
 610 }
 611
 612 module_init(rackmeter_init);
 613 module_exit(rackmeter_exit);
 614
 615
 616 MODULE_LICENSE("GPL");
 617 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
 618 MODULE_DESCRIPTION("RackMeter: Support vu-meter on XServe front panel");