rack-meter.c

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/*
 * RackMac vu-meter driver
 *
 * (c) Copyright 2006 Benjamin Herrenschmidt, IBM Corp.
 *                    <[email protected]>
 *
 * 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/slab.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)
{
    u64 retval;

    retval = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE] +
         kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT];

    if (rackmeter_ignore_nice)
        retval += kcpustat_cpu(cpu).cpustat[CPUTIME_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) (cur_jiffies - rcpu->prev_wall);
    rcpu->prev_wall = cur_jiffies;

    total_idle_ticks = get_cpu_idle_time(cpu);
    idle_ticks = (unsigned int) (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 rackmeter_stop_cpu_sniffer(struct rackmeter *rm)
{
    cancel_delayed_work_sync(&rm->cpu[0].sniffer);
    cancel_delayed_work_sync(&rm->cpu[1].sniffer);
}

static int __devinit 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.dev.of_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.dev.of_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_driver = {
    .driver = {
        .name = "rackmeter",
        .owner = THIS_MODULE,
        .of_match_table = rackmeter_match,
    },
    .probe = rackmeter_probe,
    .remove = __devexit_p(rackmeter_remove),
    .shutdown = rackmeter_shutdown,
};


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

    return macio_register_driver(&rackmeter_driver);
}

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

    macio_unregister_driver(&rackmeter_driver);
}

module_init(rackmeter_init);
module_exit(rackmeter_exit);


MODULE_LICENSE("GPL");
MODULE_AUTHOR("Benjamin Herrenschmidt <[email protected]>");
MODULE_DESCRIPTION("RackMeter: Support vu-meter on XServe front panel");