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rack-meter.c

/*
 * RackMac vu-meter driver
 *
 * (c) Copyright 2006 Benjamin Herrenschmidt, IBM Corp.
 *                    <benh@kernel.crashing.org>
 *
 * Released under the term of the GNU GPL v2.
 *
 * Support the CPU-meter LEDs of the Xserve G5
 *
 * TODO: Implement PWM to do variable intensity and provide userland
 * interface for fun. Also, the CPU-meter could be made nicer by being
 * a bit less "immediate" but giving instead a more average load over
 * time. Patches welcome :-)
 *
 */
#undef DEBUG

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/dma-mapping.h>
#include <linux/kernel_stat.h>

#include <asm/io.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/pmac_feature.h>
#include <asm/dbdma.h>
#include <asm/macio.h>
#include <asm/keylargo.h>

/* Number of samples in a sample buffer */
#define SAMPLE_COUNT          256

/* CPU meter sampling rate in ms */
#define CPU_SAMPLING_RATE     250

struct rackmeter_dma {
      struct dbdma_cmd  cmd[4]                  ____cacheline_aligned;
      u32               mark              ____cacheline_aligned;
      u32               buf1[SAMPLE_COUNT]      ____cacheline_aligned;
      u32               buf2[SAMPLE_COUNT]      ____cacheline_aligned;
} ____cacheline_aligned;

struct rackmeter_cpu {
      struct delayed_work     sniffer;
      struct rackmeter  *rm;
      cputime64_t       prev_wall;
      cputime64_t       prev_idle;
      int               zero;
} ____cacheline_aligned;

struct rackmeter {
      struct macio_dev        *mdev;
      unsigned int                  irq;
      struct device_node            *i2s;
      u8                      *ubuf;
      struct dbdma_regs __iomem     *dma_regs;
      void __iomem                  *i2s_regs;
      dma_addr_t              dma_buf_p;
      struct rackmeter_dma          *dma_buf_v;
      int                     stale_irq;
      struct rackmeter_cpu          cpu[2];
      int                     paused;
      struct mutex                  sem;
};

/* To be set as a tunable */
static int rackmeter_ignore_nice;

/* This GPIO is whacked by the OS X driver when initializing */
#define RACKMETER_MAGIC_GPIO  0x78

/* This is copied from cpufreq_ondemand, maybe we should put it in
 * a common header somewhere
 */
static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
{
      cputime64_t retval;

      retval = cputime64_add(kstat_cpu(cpu).cpustat.idle,
                  kstat_cpu(cpu).cpustat.iowait);

      if (rackmeter_ignore_nice)
            retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice);

      return retval;
}

static void rackmeter_setup_i2s(struct rackmeter *rm)
{
      struct macio_chip *macio = rm->mdev->bus->chip;

      /* First whack magic GPIO */
      pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, RACKMETER_MAGIC_GPIO, 5);


      /* Call feature code to enable the sound channel and the proper
       * clock sources
       */
      pmac_call_feature(PMAC_FTR_SOUND_CHIP_ENABLE, rm->i2s, 0, 1);

      /* Power i2s and stop i2s clock. We whack MacIO FCRs directly for now.
       * This is a bit racy, thus we should add new platform functions to
       * handle that. snd-aoa needs that too
       */
      MACIO_BIS(KEYLARGO_FCR1, KL1_I2S0_ENABLE);
      MACIO_BIC(KEYLARGO_FCR1, KL1_I2S0_CLK_ENABLE_BIT);
      (void)MACIO_IN32(KEYLARGO_FCR1);
      udelay(10);

      /* Then setup i2s. For now, we use the same magic value that
       * the OS X driver seems to use. We might want to play around
       * with the clock divisors later
       */
      out_le32(rm->i2s_regs + 0x10, 0x01fa0000);
      (void)in_le32(rm->i2s_regs + 0x10);
      udelay(10);

      /* Fully restart i2s*/
      MACIO_BIS(KEYLARGO_FCR1, KL1_I2S0_CELL_ENABLE |
              KL1_I2S0_CLK_ENABLE_BIT);
      (void)MACIO_IN32(KEYLARGO_FCR1);
      udelay(10);
}

static void rackmeter_set_default_pattern(struct rackmeter *rm)
{
      int i;

      for (i = 0; i < 16; i++) {
            if (i < 8)
                  rm->ubuf[i] = (i & 1) * 255;
            else
                  rm->ubuf[i] = ((~i) & 1) * 255;
      }
}

static void rackmeter_do_pause(struct rackmeter *rm, int pause)
{
      struct rackmeter_dma *rdma = rm->dma_buf_v;

      pr_debug("rackmeter: %s\n", pause ? "paused" : "started");

      rm->paused = pause;
      if (pause) {
            DBDMA_DO_STOP(rm->dma_regs);
            return;
      }
      memset(rdma->buf1, 0, SAMPLE_COUNT & sizeof(u32));
      memset(rdma->buf2, 0, SAMPLE_COUNT & sizeof(u32));

      rm->dma_buf_v->mark = 0;

      mb();
      out_le32(&rm->dma_regs->cmdptr_hi, 0);
      out_le32(&rm->dma_regs->cmdptr, rm->dma_buf_p);
      out_le32(&rm->dma_regs->control, (RUN << 16) | RUN);
}

static void rackmeter_setup_dbdma(struct rackmeter *rm)
{
      struct rackmeter_dma *db = rm->dma_buf_v;
      struct dbdma_cmd *cmd = db->cmd;

      /* Make sure dbdma is reset */
      DBDMA_DO_RESET(rm->dma_regs);

      pr_debug("rackmeter: mark offset=0x%zx\n",
             offsetof(struct rackmeter_dma, mark));
      pr_debug("rackmeter: buf1 offset=0x%zx\n",
             offsetof(struct rackmeter_dma, buf1));
      pr_debug("rackmeter: buf2 offset=0x%zx\n",
             offsetof(struct rackmeter_dma, buf2));

      /* Prepare 4 dbdma commands for the 2 buffers */
      memset(cmd, 0, 4 * sizeof(struct dbdma_cmd));
      st_le16(&cmd->req_count, 4);
      st_le16(&cmd->command, STORE_WORD | INTR_ALWAYS | KEY_SYSTEM);
      st_le32(&cmd->phy_addr, rm->dma_buf_p +
            offsetof(struct rackmeter_dma, mark));
      st_le32(&cmd->cmd_dep, 0x02000000);
      cmd++;

      st_le16(&cmd->req_count, SAMPLE_COUNT * 4);
      st_le16(&cmd->command, OUTPUT_MORE);
      st_le32(&cmd->phy_addr, rm->dma_buf_p +
            offsetof(struct rackmeter_dma, buf1));
      cmd++;

      st_le16(&cmd->req_count, 4);
      st_le16(&cmd->command, STORE_WORD | INTR_ALWAYS | KEY_SYSTEM);
      st_le32(&cmd->phy_addr, rm->dma_buf_p +
            offsetof(struct rackmeter_dma, mark));
      st_le32(&cmd->cmd_dep, 0x01000000);
      cmd++;

      st_le16(&cmd->req_count, SAMPLE_COUNT * 4);
      st_le16(&cmd->command, OUTPUT_MORE | BR_ALWAYS);
      st_le32(&cmd->phy_addr, rm->dma_buf_p +
            offsetof(struct rackmeter_dma, buf2));
      st_le32(&cmd->cmd_dep, rm->dma_buf_p);

      rackmeter_do_pause(rm, 0);
}

static void rackmeter_do_timer(struct work_struct *work)
{
      struct rackmeter_cpu *rcpu =
            container_of(work, struct rackmeter_cpu, sniffer.work);
      struct rackmeter *rm = rcpu->rm;
      unsigned int cpu = smp_processor_id();
      cputime64_t cur_jiffies, total_idle_ticks;
      unsigned int total_ticks, idle_ticks;
      int i, offset, load, cumm, pause;

      cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
      total_ticks = (unsigned int)cputime64_sub(cur_jiffies,
                                      rcpu->prev_wall);
      rcpu->prev_wall = cur_jiffies;

      total_idle_ticks = get_cpu_idle_time(cpu);
      idle_ticks = (unsigned int) cputime64_sub(total_idle_ticks,
                        rcpu->prev_idle);
      rcpu->prev_idle = total_idle_ticks;

      /* We do a very dumb calculation to update the LEDs for now,
       * we'll do better once we have actual PWM implemented
       */
      load = (9 * (total_ticks - idle_ticks)) / total_ticks;

      offset = cpu << 3;
      cumm = 0;
      for (i = 0; i < 8; i++) {
            u8 ub = (load > i) ? 0xff : 0;
            rm->ubuf[i + offset] = ub;
            cumm |= ub;
      }
      rcpu->zero = (cumm == 0);

      /* Now check if LEDs are all 0, we can stop DMA */
      pause = (rm->cpu[0].zero && rm->cpu[1].zero);
      if (pause != rm->paused) {
            mutex_lock(&rm->sem);
            pause = (rm->cpu[0].zero && rm->cpu[1].zero);
            rackmeter_do_pause(rm, pause);
            mutex_unlock(&rm->sem);
      }
      schedule_delayed_work_on(cpu, &rcpu->sniffer,
                         msecs_to_jiffies(CPU_SAMPLING_RATE));
}

static void __devinit rackmeter_init_cpu_sniffer(struct rackmeter *rm)
{
      unsigned int cpu;

      /* This driver works only with 1 or 2 CPUs numbered 0 and 1,
       * but that's really all we have on Apple Xserve. It doesn't
       * play very nice with CPU hotplug neither but we don't do that
       * on those machines yet
       */

      rm->cpu[0].rm = rm;
      INIT_DELAYED_WORK(&rm->cpu[0].sniffer, rackmeter_do_timer);
      rm->cpu[1].rm = rm;
      INIT_DELAYED_WORK(&rm->cpu[1].sniffer, rackmeter_do_timer);

      for_each_online_cpu(cpu) {
            struct rackmeter_cpu *rcpu;

            if (cpu > 1)
                  continue;
            rcpu = &rm->cpu[cpu];;
            rcpu->prev_idle = get_cpu_idle_time(cpu);
            rcpu->prev_wall = jiffies64_to_cputime64(get_jiffies_64());
            schedule_delayed_work_on(cpu, &rm->cpu[cpu].sniffer,
                               msecs_to_jiffies(CPU_SAMPLING_RATE));
      }
}

static void __devexit rackmeter_stop_cpu_sniffer(struct rackmeter *rm)
{
      cancel_rearming_delayed_work(&rm->cpu[0].sniffer);
      cancel_rearming_delayed_work(&rm->cpu[1].sniffer);
}

static int rackmeter_setup(struct rackmeter *rm)
{
      pr_debug("rackmeter: setting up i2s..\n");
      rackmeter_setup_i2s(rm);

      pr_debug("rackmeter: setting up default pattern..\n");
      rackmeter_set_default_pattern(rm);

      pr_debug("rackmeter: setting up dbdma..\n");
      rackmeter_setup_dbdma(rm);

      pr_debug("rackmeter: start CPU measurements..\n");
      rackmeter_init_cpu_sniffer(rm);

      printk(KERN_INFO "RackMeter initialized\n");

      return 0;
}

/*  XXX FIXME: No PWM yet, this is 0/1 */
static u32 rackmeter_calc_sample(struct rackmeter *rm, unsigned int index)
{
      int led;
      u32 sample = 0;

      for (led = 0; led < 16; led++) {
            sample >>= 1;
            sample |= ((rm->ubuf[led] >= 0x80) << 15);
      }
      return (sample << 17) | (sample >> 15);
}

static irqreturn_t rackmeter_irq(int irq, void *arg)
{
      struct rackmeter *rm = arg;
      struct rackmeter_dma *db = rm->dma_buf_v;
      unsigned int mark, i;
      u32 *buf;

      /* Flush PCI buffers with an MMIO read. Maybe we could actually
       * check the status one day ... in case things go wrong, though
       * this never happened to me
       */
      (void)in_le32(&rm->dma_regs->status);

      /* Make sure the CPU gets us in order */
      rmb();

      /* Read mark */
      mark = db->mark;
      if (mark != 1 && mark != 2) {
            printk(KERN_WARNING "rackmeter: Incorrect DMA mark 0x%08x\n",
                   mark);
            /* We allow for 3 errors like that (stale DBDMA irqs) */
            if (++rm->stale_irq > 3) {
                  printk(KERN_ERR "rackmeter: Too many errors,"
                         " stopping DMA\n");
                  DBDMA_DO_RESET(rm->dma_regs);
            }
            return IRQ_HANDLED;
      }

      /* Next buffer we need to fill is mark value */
      buf = mark == 1 ? db->buf1 : db->buf2;

      /* Fill it now. This routine converts the 8 bits depth sample array
       * into the PWM bitmap for each LED.
       */
      for (i = 0; i < SAMPLE_COUNT; i++)
            buf[i] = rackmeter_calc_sample(rm, i);


      return IRQ_HANDLED;
}

static int __devinit rackmeter_probe(struct macio_dev* mdev,
                             const struct of_device_id *match)
{
      struct device_node *i2s = NULL, *np = NULL;
      struct rackmeter *rm = NULL;
      struct resource ri2s, rdma;
      int rc = -ENODEV;

      pr_debug("rackmeter_probe()\n");

      /* Get i2s-a node */
      while ((i2s = of_get_next_child(mdev->ofdev.node, i2s)) != NULL)
             if (strcmp(i2s->name, "i2s-a") == 0)
                   break;
      if (i2s == NULL) {
            pr_debug("  i2s-a child not found\n");
            goto bail;
      }
      /* Get lightshow or virtual sound */
      while ((np = of_get_next_child(i2s, np)) != NULL) {
             if (strcmp(np->name, "lightshow") == 0)
                   break;
             if ((strcmp(np->name, "sound") == 0) &&
               of_get_property(np, "virtual", NULL) != NULL)
                   break;
      }
      if (np == NULL) {
            pr_debug("  lightshow or sound+virtual child not found\n");
            goto bail;
      }

      /* Create and initialize our instance data */
      rm = kzalloc(sizeof(struct rackmeter), GFP_KERNEL);
      if (rm == NULL) {
            printk(KERN_ERR "rackmeter: failed to allocate memory !\n");
            rc = -ENOMEM;
            goto bail_release;
      }
      rm->mdev = mdev;
      rm->i2s = i2s;
      mutex_init(&rm->sem);
      dev_set_drvdata(&mdev->ofdev.dev, rm);
      /* Check resources availability. We need at least resource 0 and 1 */
#if 0 /* Use that when i2s-a is finally an mdev per-se */
      if (macio_resource_count(mdev) < 2 || macio_irq_count(mdev) < 2) {
            printk(KERN_ERR
                   "rackmeter: found match but lacks resources: %s"
                   " (%d resources, %d interrupts)\n",
                   mdev->ofdev.node->full_name);
            rc = -ENXIO;
            goto bail_free;
      }
      if (macio_request_resources(mdev, "rackmeter")) {
            printk(KERN_ERR
                   "rackmeter: failed to request resources: %s\n",
                   mdev->ofdev.node->full_name);
            rc = -EBUSY;
            goto bail_free;
      }
      rm->irq = macio_irq(mdev, 1);
#else
      rm->irq = irq_of_parse_and_map(i2s, 1);
      if (rm->irq == NO_IRQ ||
          of_address_to_resource(i2s, 0, &ri2s) ||
          of_address_to_resource(i2s, 1, &rdma)) {
            printk(KERN_ERR
                   "rackmeter: found match but lacks resources: %s",
                   mdev->ofdev.node->full_name);
            rc = -ENXIO;
            goto bail_free;
      }
#endif

      pr_debug("  i2s @0x%08x\n", (unsigned int)ri2s.start);
      pr_debug("  dma @0x%08x\n", (unsigned int)rdma.start);
      pr_debug("  irq %d\n", rm->irq);

      rm->ubuf = (u8 *)__get_free_page(GFP_KERNEL);
      if (rm->ubuf == NULL) {
            printk(KERN_ERR
                   "rackmeter: failed to allocate samples page !\n");
            rc = -ENOMEM;
            goto bail_release;
      }

      rm->dma_buf_v = dma_alloc_coherent(&macio_get_pci_dev(mdev)->dev,
                                 sizeof(struct rackmeter_dma),
                                 &rm->dma_buf_p, GFP_KERNEL);
      if (rm->dma_buf_v == NULL) {
            printk(KERN_ERR
                   "rackmeter: failed to allocate dma buffer !\n");
            rc = -ENOMEM;
            goto bail_free_samples;
      }
#if 0
      rm->i2s_regs = ioremap(macio_resource_start(mdev, 0), 0x1000);
#else
      rm->i2s_regs = ioremap(ri2s.start, 0x1000);
#endif
      if (rm->i2s_regs == NULL) {
            printk(KERN_ERR
                   "rackmeter: failed to map i2s registers !\n");
            rc = -ENXIO;
            goto bail_free_dma;
      }
#if 0
      rm->dma_regs = ioremap(macio_resource_start(mdev, 1), 0x100);
#else
      rm->dma_regs = ioremap(rdma.start, 0x100);
#endif
      if (rm->dma_regs == NULL) {
            printk(KERN_ERR
                   "rackmeter: failed to map dma registers !\n");
            rc = -ENXIO;
            goto bail_unmap_i2s;
      }

      rc = rackmeter_setup(rm);
      if (rc) {
            printk(KERN_ERR
                   "rackmeter: failed to initialize !\n");
            rc = -ENXIO;
            goto bail_unmap_dma;
      }

      rc = request_irq(rm->irq, rackmeter_irq, 0, "rackmeter", rm);
      if (rc != 0) {
            printk(KERN_ERR
                   "rackmeter: failed to request interrupt !\n");
            goto bail_stop_dma;
      }
      of_node_put(np);
      return 0;

 bail_stop_dma:
      DBDMA_DO_RESET(rm->dma_regs);
 bail_unmap_dma:
      iounmap(rm->dma_regs);
 bail_unmap_i2s:
      iounmap(rm->i2s_regs);
 bail_free_dma:
      dma_free_coherent(&macio_get_pci_dev(mdev)->dev,
                    sizeof(struct rackmeter_dma),
                    rm->dma_buf_v, rm->dma_buf_p);
 bail_free_samples:
      free_page((unsigned long)rm->ubuf);
 bail_release:
#if 0
      macio_release_resources(mdev);
#endif
 bail_free:
      kfree(rm);
 bail:
      of_node_put(i2s);
      of_node_put(np);
      dev_set_drvdata(&mdev->ofdev.dev, NULL);
      return rc;
}

static int __devexit rackmeter_remove(struct macio_dev* mdev)
{
      struct rackmeter *rm = dev_get_drvdata(&mdev->ofdev.dev);

      /* Stop CPU sniffer timer & work queues */
      rackmeter_stop_cpu_sniffer(rm);

      /* Clear reference to private data */
      dev_set_drvdata(&mdev->ofdev.dev, NULL);

      /* Stop/reset dbdma */
      DBDMA_DO_RESET(rm->dma_regs);

      /* Release the IRQ */
      free_irq(rm->irq, rm);

      /* Unmap registers */
      iounmap(rm->dma_regs);
      iounmap(rm->i2s_regs);

      /* Free DMA */
      dma_free_coherent(&macio_get_pci_dev(mdev)->dev,
                    sizeof(struct rackmeter_dma),
                    rm->dma_buf_v, rm->dma_buf_p);

      /* Free samples */
      free_page((unsigned long)rm->ubuf);

#if 0
      /* Release resources */
      macio_release_resources(mdev);
#endif

      /* Get rid of me */
      kfree(rm);

      return 0;
}

static int rackmeter_shutdown(struct macio_dev* mdev)
{
      struct rackmeter *rm = dev_get_drvdata(&mdev->ofdev.dev);

      if (rm == NULL)
            return -ENODEV;

      /* Stop CPU sniffer timer & work queues */
      rackmeter_stop_cpu_sniffer(rm);

      /* Stop/reset dbdma */
      DBDMA_DO_RESET(rm->dma_regs);

      return 0;
}

static struct of_device_id rackmeter_match[] = {
      { .name = "i2s" },
      { }
};

static struct macio_driver rackmeter_drv = {
      .name = "rackmeter",
      .owner = THIS_MODULE,
      .match_table = rackmeter_match,
      .probe = rackmeter_probe,
      .remove = rackmeter_remove,
      .shutdown = rackmeter_shutdown,
};


static int __init rackmeter_init(void)
{
      pr_debug("rackmeter_init()\n");

      return macio_register_driver(&rackmeter_drv);
}

static void __exit rackmeter_exit(void)
{
      pr_debug("rackmeter_exit()\n");

      macio_unregister_driver(&rackmeter_drv);
}

module_init(rackmeter_init);
module_exit(rackmeter_exit);


MODULE_LICENSE("GPL");
MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("RackMeter: Support vu-meter on XServe front panel");

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