mdesc.c

Go to the documentation of this file.

/* mdesc.c: Sun4V machine description handling.
 *
 * Copyright (C) 2007, 2008 David S. Miller <[email protected]>
 */
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/memblock.h>
#include <linux/log2.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/bootmem.h>
#include <linux/export.h>

#include <asm/cpudata.h>
#include <asm/hypervisor.h>
#include <asm/mdesc.h>
#include <asm/prom.h>
#include <asm/uaccess.h>
#include <asm/oplib.h>
#include <asm/smp.h>

/* Unlike the OBP device tree, the machine description is a full-on
 * DAG.  An arbitrary number of ARCs are possible from one
 * node to other nodes and thus we can't use the OBP device_node
 * data structure to represent these nodes inside of the kernel.
 *
 * Actually, it isn't even a DAG, because there are back pointers
 * which create cycles in the graph.
 *
 * mdesc_hdr and mdesc_elem describe the layout of the data structure
 * we get from the Hypervisor.
 */
struct mdesc_hdr {
    u32 version; /* Transport version */
    u32 node_sz; /* node block size */
    u32 name_sz; /* name block size */
    u32 data_sz; /* data block size */
} __attribute__((aligned(16)));

struct mdesc_elem {
    u8  tag;
#define MD_LIST_END 0x00
#define MD_NODE     0x4e
#define MD_NODE_END 0x45
#define MD_NOOP     0x20
#define MD_PROP_ARC 0x61
#define MD_PROP_VAL 0x76
#define MD_PROP_STR 0x73
#define MD_PROP_DATA    0x64
    u8  name_len;
    u16 resv;
    u32 name_offset;
    union {
        struct {
            u32 data_len;
            u32 data_offset;
        } data;
        u64 val;
    } d;
};

struct mdesc_mem_ops {
    struct mdesc_handle *(*alloc)(unsigned int mdesc_size);
    void (*free)(struct mdesc_handle *handle);
};

struct mdesc_handle {
    struct list_head    list;
    struct mdesc_mem_ops    *mops;
    void            *self_base;
    atomic_t        refcnt;
    unsigned int        handle_size;
    struct mdesc_hdr    mdesc;
};

static void mdesc_handle_init(struct mdesc_handle *hp,
                  unsigned int handle_size,
                  void *base)
{
    BUG_ON(((unsigned long)&hp->mdesc) & (16UL - 1));

    memset(hp, 0, handle_size);
    INIT_LIST_HEAD(&hp->list);
    hp->self_base = base;
    atomic_set(&hp->refcnt, 1);
    hp->handle_size = handle_size;
}

static struct mdesc_handle * __init mdesc_memblock_alloc(unsigned int mdesc_size)
{
    unsigned int handle_size, alloc_size;
    struct mdesc_handle *hp;
    unsigned long paddr;

    handle_size = (sizeof(struct mdesc_handle) -
               sizeof(struct mdesc_hdr) +
               mdesc_size);
    alloc_size = PAGE_ALIGN(handle_size);

    paddr = memblock_alloc(alloc_size, PAGE_SIZE);

    hp = NULL;
    if (paddr) {
        hp = __va(paddr);
        mdesc_handle_init(hp, handle_size, hp);
    }
    return hp;
}

static void __init mdesc_memblock_free(struct mdesc_handle *hp)
{
    unsigned int alloc_size;
    unsigned long start;

    BUG_ON(atomic_read(&hp->refcnt) != 0);
    BUG_ON(!list_empty(&hp->list));

    alloc_size = PAGE_ALIGN(hp->handle_size);
    start = __pa(hp);
    free_bootmem_late(start, alloc_size);
}

static struct mdesc_mem_ops memblock_mdesc_ops = {
    .alloc = mdesc_memblock_alloc,
    .free  = mdesc_memblock_free,
};

static struct mdesc_handle *mdesc_kmalloc(unsigned int mdesc_size)
{
    unsigned int handle_size;
    void *base;

    handle_size = (sizeof(struct mdesc_handle) -
               sizeof(struct mdesc_hdr) +
               mdesc_size);

    base = kmalloc(handle_size + 15, GFP_KERNEL | __GFP_NOFAIL);
    if (base) {
        struct mdesc_handle *hp;
        unsigned long addr;

        addr = (unsigned long)base;
        addr = (addr + 15UL) & ~15UL;
        hp = (struct mdesc_handle *) addr;

        mdesc_handle_init(hp, handle_size, base);
        return hp;
    }

    return NULL;
}

static void mdesc_kfree(struct mdesc_handle *hp)
{
    BUG_ON(atomic_read(&hp->refcnt) != 0);
    BUG_ON(!list_empty(&hp->list));

    kfree(hp->self_base);
}

static struct mdesc_mem_ops kmalloc_mdesc_memops = {
    .alloc = mdesc_kmalloc,
    .free  = mdesc_kfree,
};

static struct mdesc_handle *mdesc_alloc(unsigned int mdesc_size,
                    struct mdesc_mem_ops *mops)
{
    struct mdesc_handle *hp = mops->alloc(mdesc_size);

    if (hp)
        hp->mops = mops;

    return hp;
}

static void mdesc_free(struct mdesc_handle *hp)
{
    hp->mops->free(hp);
}

static struct mdesc_handle *cur_mdesc;
static LIST_HEAD(mdesc_zombie_list);
static DEFINE_SPINLOCK(mdesc_lock);

struct mdesc_handle *mdesc_grab(void)
{
    struct mdesc_handle *hp;
    unsigned long flags;

    spin_lock_irqsave(&mdesc_lock, flags);
    hp = cur_mdesc;
    if (hp)
        atomic_inc(&hp->refcnt);
    spin_unlock_irqrestore(&mdesc_lock, flags);

    return hp;
}
EXPORT_SYMBOL(mdesc_grab);

void mdesc_release(struct mdesc_handle *hp)
{
    unsigned long flags;

    spin_lock_irqsave(&mdesc_lock, flags);
    if (atomic_dec_and_test(&hp->refcnt)) {
        list_del_init(&hp->list);
        hp->mops->free(hp);
    }
    spin_unlock_irqrestore(&mdesc_lock, flags);
}
EXPORT_SYMBOL(mdesc_release);

static DEFINE_MUTEX(mdesc_mutex);
static struct mdesc_notifier_client *client_list;

void mdesc_register_notifier(struct mdesc_notifier_client *client)
{
    u64 node;

    mutex_lock(&mdesc_mutex);
    client->next = client_list;
    client_list = client;

    mdesc_for_each_node_by_name(cur_mdesc, node, client->node_name)
        client->add(cur_mdesc, node);

    mutex_unlock(&mdesc_mutex);
}

static const u64 *parent_cfg_handle(struct mdesc_handle *hp, u64 node)
{
    const u64 *id;
    u64 a;

    id = NULL;
    mdesc_for_each_arc(a, hp, node, MDESC_ARC_TYPE_BACK) {
        u64 target;

        target = mdesc_arc_target(hp, a);
        id = mdesc_get_property(hp, target,
                    "cfg-handle", NULL);
        if (id)
            break;
    }

    return id;
}

/* Run 'func' on nodes which are in A but not in B.  */
static void invoke_on_missing(const char *name,
                  struct mdesc_handle *a,
                  struct mdesc_handle *b,
                  void (*func)(struct mdesc_handle *, u64))
{
    u64 node;

    mdesc_for_each_node_by_name(a, node, name) {
        int found = 0, is_vdc_port = 0;
        const char *name_prop;
        const u64 *id;
        u64 fnode;

        name_prop = mdesc_get_property(a, node, "name", NULL);
        if (name_prop && !strcmp(name_prop, "vdc-port")) {
            is_vdc_port = 1;
            id = parent_cfg_handle(a, node);
        } else
            id = mdesc_get_property(a, node, "id", NULL);

        if (!id) {
            printk(KERN_ERR "MD: Cannot find ID for %s node.\n",
                   (name_prop ? name_prop : name));
            continue;
        }

        mdesc_for_each_node_by_name(b, fnode, name) {
            const u64 *fid;

            if (is_vdc_port) {
                name_prop = mdesc_get_property(b, fnode,
                                   "name", NULL);
                if (!name_prop ||
                    strcmp(name_prop, "vdc-port"))
                    continue;
                fid = parent_cfg_handle(b, fnode);
                if (!fid) {
                    printk(KERN_ERR "MD: Cannot find ID "
                           "for vdc-port node.\n");
                    continue;
                }
            } else
                fid = mdesc_get_property(b, fnode,
                             "id", NULL);

            if (*id == *fid) {
                found = 1;
                break;
            }
        }
        if (!found)
            func(a, node);
    }
}

static void notify_one(struct mdesc_notifier_client *p,
               struct mdesc_handle *old_hp,
               struct mdesc_handle *new_hp)
{
    invoke_on_missing(p->node_name, old_hp, new_hp, p->remove);
    invoke_on_missing(p->node_name, new_hp, old_hp, p->add);
}

static void mdesc_notify_clients(struct mdesc_handle *old_hp,
                 struct mdesc_handle *new_hp)
{
    struct mdesc_notifier_client *p = client_list;

    while (p) {
        notify_one(p, old_hp, new_hp);
        p = p->next;
    }
}

void mdesc_update(void)
{
    unsigned long len, real_len, status;
    struct mdesc_handle *hp, *orig_hp;
    unsigned long flags;

    mutex_lock(&mdesc_mutex);

    (void) sun4v_mach_desc(0UL, 0UL, &len);

    hp = mdesc_alloc(len, &kmalloc_mdesc_memops);
    if (!hp) {
        printk(KERN_ERR "MD: mdesc alloc fails\n");
        goto out;
    }

    status = sun4v_mach_desc(__pa(&hp->mdesc), len, &real_len);
    if (status != HV_EOK || real_len > len) {
        printk(KERN_ERR "MD: mdesc reread fails with %lu\n",
               status);
        atomic_dec(&hp->refcnt);
        mdesc_free(hp);
        goto out;
    }

    spin_lock_irqsave(&mdesc_lock, flags);
    orig_hp = cur_mdesc;
    cur_mdesc = hp;
    spin_unlock_irqrestore(&mdesc_lock, flags);

    mdesc_notify_clients(orig_hp, hp);

    spin_lock_irqsave(&mdesc_lock, flags);
    if (atomic_dec_and_test(&orig_hp->refcnt))
        mdesc_free(orig_hp);
    else
        list_add(&orig_hp->list, &mdesc_zombie_list);
    spin_unlock_irqrestore(&mdesc_lock, flags);

out:
    mutex_unlock(&mdesc_mutex);
}

static struct mdesc_elem *node_block(struct mdesc_hdr *mdesc)
{
    return (struct mdesc_elem *) (mdesc + 1);
}

static void *name_block(struct mdesc_hdr *mdesc)
{
    return ((void *) node_block(mdesc)) + mdesc->node_sz;
}

static void *data_block(struct mdesc_hdr *mdesc)
{
    return ((void *) name_block(mdesc)) + mdesc->name_sz;
}

u64 mdesc_node_by_name(struct mdesc_handle *hp,
               u64 from_node, const char *name)
{
    struct mdesc_elem *ep = node_block(&hp->mdesc);
    const char *names = name_block(&hp->mdesc);
    u64 last_node = hp->mdesc.node_sz / 16;
    u64 ret;

    if (from_node == MDESC_NODE_NULL) {
        ret = from_node = 0;
    } else if (from_node >= last_node) {
        return MDESC_NODE_NULL;
    } else {
        ret = ep[from_node].d.val;
    }

    while (ret < last_node) {
        if (ep[ret].tag != MD_NODE)
            return MDESC_NODE_NULL;
        if (!strcmp(names + ep[ret].name_offset, name))
            break;
        ret = ep[ret].d.val;
    }
    if (ret >= last_node)
        ret = MDESC_NODE_NULL;
    return ret;
}
EXPORT_SYMBOL(mdesc_node_by_name);

const void *mdesc_get_property(struct mdesc_handle *hp, u64 node,
                   const char *name, int *lenp)
{
    const char *names = name_block(&hp->mdesc);
    u64 last_node = hp->mdesc.node_sz / 16;
    void *data = data_block(&hp->mdesc);
    struct mdesc_elem *ep;

    if (node == MDESC_NODE_NULL || node >= last_node)
        return NULL;

    ep = node_block(&hp->mdesc) + node;
    ep++;
    for (; ep->tag != MD_NODE_END; ep++) {
        void *val = NULL;
        int len = 0;

        switch (ep->tag) {
        case MD_PROP_VAL:
            val = &ep->d.val;
            len = 8;
            break;

        case MD_PROP_STR:
        case MD_PROP_DATA:
            val = data + ep->d.data.data_offset;
            len = ep->d.data.data_len;
            break;

        default:
            break;
        }
        if (!val)
            continue;

        if (!strcmp(names + ep->name_offset, name)) {
            if (lenp)
                *lenp = len;
            return val;
        }
    }

    return NULL;
}
EXPORT_SYMBOL(mdesc_get_property);

u64 mdesc_next_arc(struct mdesc_handle *hp, u64 from, const char *arc_type)
{
    struct mdesc_elem *ep, *base = node_block(&hp->mdesc);
    const char *names = name_block(&hp->mdesc);
    u64 last_node = hp->mdesc.node_sz / 16;

    if (from == MDESC_NODE_NULL || from >= last_node)
        return MDESC_NODE_NULL;

    ep = base + from;

    ep++;
    for (; ep->tag != MD_NODE_END; ep++) {
        if (ep->tag != MD_PROP_ARC)
            continue;

        if (strcmp(names + ep->name_offset, arc_type))
            continue;

        return ep - base;
    }

    return MDESC_NODE_NULL;
}
EXPORT_SYMBOL(mdesc_next_arc);

u64 mdesc_arc_target(struct mdesc_handle *hp, u64 arc)
{
    struct mdesc_elem *ep, *base = node_block(&hp->mdesc);

    ep = base + arc;

    return ep->d.val;
}
EXPORT_SYMBOL(mdesc_arc_target);

const char *mdesc_node_name(struct mdesc_handle *hp, u64 node)
{
    struct mdesc_elem *ep, *base = node_block(&hp->mdesc);
    const char *names = name_block(&hp->mdesc);
    u64 last_node = hp->mdesc.node_sz / 16;

    if (node == MDESC_NODE_NULL || node >= last_node)
        return NULL;

    ep = base + node;
    if (ep->tag != MD_NODE)
        return NULL;

    return names + ep->name_offset;
}
EXPORT_SYMBOL(mdesc_node_name);

static u64 max_cpus = 64;

static void __init report_platform_properties(void)
{
    struct mdesc_handle *hp = mdesc_grab();
    u64 pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
    const char *s;
    const u64 *v;

    if (pn == MDESC_NODE_NULL) {
        prom_printf("No platform node in machine-description.\n");
        prom_halt();
    }

    s = mdesc_get_property(hp, pn, "banner-name", NULL);
    printk("PLATFORM: banner-name [%s]\n", s);
    s = mdesc_get_property(hp, pn, "name", NULL);
    printk("PLATFORM: name [%s]\n", s);

    v = mdesc_get_property(hp, pn, "hostid", NULL);
    if (v)
        printk("PLATFORM: hostid [%08llx]\n", *v);
    v = mdesc_get_property(hp, pn, "serial#", NULL);
    if (v)
        printk("PLATFORM: serial# [%08llx]\n", *v);
    v = mdesc_get_property(hp, pn, "stick-frequency", NULL);
    printk("PLATFORM: stick-frequency [%08llx]\n", *v);
    v = mdesc_get_property(hp, pn, "mac-address", NULL);
    if (v)
        printk("PLATFORM: mac-address [%llx]\n", *v);
    v = mdesc_get_property(hp, pn, "watchdog-resolution", NULL);
    if (v)
        printk("PLATFORM: watchdog-resolution [%llu ms]\n", *v);
    v = mdesc_get_property(hp, pn, "watchdog-max-timeout", NULL);
    if (v)
        printk("PLATFORM: watchdog-max-timeout [%llu ms]\n", *v);
    v = mdesc_get_property(hp, pn, "max-cpus", NULL);
    if (v) {
        max_cpus = *v;
        printk("PLATFORM: max-cpus [%llu]\n", max_cpus);
    }

#ifdef CONFIG_SMP
    {
        int max_cpu, i;

        if (v) {
            max_cpu = *v;
            if (max_cpu > NR_CPUS)
                max_cpu = NR_CPUS;
        } else {
            max_cpu = NR_CPUS;
        }
        for (i = 0; i < max_cpu; i++)
            set_cpu_possible(i, true);
    }
#endif

    mdesc_release(hp);
}

static void __cpuinit fill_in_one_cache(cpuinfo_sparc *c,
                    struct mdesc_handle *hp,
                    u64 mp)
{
    const u64 *level = mdesc_get_property(hp, mp, "level", NULL);
    const u64 *size = mdesc_get_property(hp, mp, "size", NULL);
    const u64 *line_size = mdesc_get_property(hp, mp, "line-size", NULL);
    const char *type;
    int type_len;

    type = mdesc_get_property(hp, mp, "type", &type_len);

    switch (*level) {
    case 1:
        if (of_find_in_proplist(type, "instn", type_len)) {
            c->icache_size = *size;
            c->icache_line_size = *line_size;
        } else if (of_find_in_proplist(type, "data", type_len)) {
            c->dcache_size = *size;
            c->dcache_line_size = *line_size;
        }
        break;

    case 2:
        c->ecache_size = *size;
        c->ecache_line_size = *line_size;
        break;

    default:
        break;
    }

    if (*level == 1) {
        u64 a;

        mdesc_for_each_arc(a, hp, mp, MDESC_ARC_TYPE_FWD) {
            u64 target = mdesc_arc_target(hp, a);
            const char *name = mdesc_node_name(hp, target);

            if (!strcmp(name, "cache"))
                fill_in_one_cache(c, hp, target);
        }
    }
}

static void __cpuinit mark_core_ids(struct mdesc_handle *hp, u64 mp, int core_id)
{
    u64 a;

    mdesc_for_each_arc(a, hp, mp, MDESC_ARC_TYPE_BACK) {
        u64 t = mdesc_arc_target(hp, a);
        const char *name;
        const u64 *id;

        name = mdesc_node_name(hp, t);
        if (!strcmp(name, "cpu")) {
            id = mdesc_get_property(hp, t, "id", NULL);
            if (*id < NR_CPUS)
                cpu_data(*id).core_id = core_id;
        } else {
            u64 j;

            mdesc_for_each_arc(j, hp, t, MDESC_ARC_TYPE_BACK) {
                u64 n = mdesc_arc_target(hp, j);
                const char *n_name;

                n_name = mdesc_node_name(hp, n);
                if (strcmp(n_name, "cpu"))
                    continue;

                id = mdesc_get_property(hp, n, "id", NULL);
                if (*id < NR_CPUS)
                    cpu_data(*id).core_id = core_id;
            }
        }
    }
}

static void __cpuinit set_core_ids(struct mdesc_handle *hp)
{
    int idx;
    u64 mp;

    idx = 1;
    mdesc_for_each_node_by_name(hp, mp, "cache") {
        const u64 *level;
        const char *type;
        int len;

        level = mdesc_get_property(hp, mp, "level", NULL);
        if (*level != 1)
            continue;

        type = mdesc_get_property(hp, mp, "type", &len);
        if (!of_find_in_proplist(type, "instn", len))
            continue;

        mark_core_ids(hp, mp, idx);

        idx++;
    }
}

static void __cpuinit mark_proc_ids(struct mdesc_handle *hp, u64 mp, int proc_id)
{
    u64 a;

    mdesc_for_each_arc(a, hp, mp, MDESC_ARC_TYPE_BACK) {
        u64 t = mdesc_arc_target(hp, a);
        const char *name;
        const u64 *id;

        name = mdesc_node_name(hp, t);
        if (strcmp(name, "cpu"))
            continue;

        id = mdesc_get_property(hp, t, "id", NULL);
        if (*id < NR_CPUS)
            cpu_data(*id).proc_id = proc_id;
    }
}

static void __cpuinit __set_proc_ids(struct mdesc_handle *hp, const char *exec_unit_name)
{
    int idx;
    u64 mp;

    idx = 0;
    mdesc_for_each_node_by_name(hp, mp, exec_unit_name) {
        const char *type;
        int len;

        type = mdesc_get_property(hp, mp, "type", &len);
        if (!of_find_in_proplist(type, "int", len) &&
            !of_find_in_proplist(type, "integer", len))
            continue;

        mark_proc_ids(hp, mp, idx);

        idx++;
    }
}

static void __cpuinit set_proc_ids(struct mdesc_handle *hp)
{
    __set_proc_ids(hp, "exec_unit");
    __set_proc_ids(hp, "exec-unit");
}

static void __cpuinit get_one_mondo_bits(const u64 *p, unsigned int *mask,
                     unsigned long def, unsigned long max)
{
    u64 val;

    if (!p)
        goto use_default;
    val = *p;

    if (!val || val >= 64)
        goto use_default;

    if (val > max)
        val = max;

    *mask = ((1U << val) * 64U) - 1U;
    return;

use_default:
    *mask = ((1U << def) * 64U) - 1U;
}

static void __cpuinit get_mondo_data(struct mdesc_handle *hp, u64 mp,
                     struct trap_per_cpu *tb)
{
    static int printed;
    const u64 *val;

    val = mdesc_get_property(hp, mp, "q-cpu-mondo-#bits", NULL);
    get_one_mondo_bits(val, &tb->cpu_mondo_qmask, 7, ilog2(max_cpus * 2));

    val = mdesc_get_property(hp, mp, "q-dev-mondo-#bits", NULL);
    get_one_mondo_bits(val, &tb->dev_mondo_qmask, 7, 8);

    val = mdesc_get_property(hp, mp, "q-resumable-#bits", NULL);
    get_one_mondo_bits(val, &tb->resum_qmask, 6, 7);

    val = mdesc_get_property(hp, mp, "q-nonresumable-#bits", NULL);
    get_one_mondo_bits(val, &tb->nonresum_qmask, 2, 2);
    if (!printed++) {
        pr_info("SUN4V: Mondo queue sizes "
            "[cpu(%u) dev(%u) r(%u) nr(%u)]\n",
            tb->cpu_mondo_qmask + 1,
            tb->dev_mondo_qmask + 1,
            tb->resum_qmask + 1,
            tb->nonresum_qmask + 1);
    }
}

static void * __cpuinit mdesc_iterate_over_cpus(void *(*func)(struct mdesc_handle *, u64, int, void *), void *arg, cpumask_t *mask)
{
    struct mdesc_handle *hp = mdesc_grab();
    void *ret = NULL;
    u64 mp;

    mdesc_for_each_node_by_name(hp, mp, "cpu") {
        const u64 *id = mdesc_get_property(hp, mp, "id", NULL);
        int cpuid = *id;

#ifdef CONFIG_SMP
        if (cpuid >= NR_CPUS) {
            printk(KERN_WARNING "Ignoring CPU %d which is "
                   ">= NR_CPUS (%d)\n",
                   cpuid, NR_CPUS);
            continue;
        }
        if (!cpumask_test_cpu(cpuid, mask))
            continue;
#endif

        ret = func(hp, mp, cpuid, arg);
        if (ret)
            goto out;
    }
out:
    mdesc_release(hp);
    return ret;
}

static void * __cpuinit record_one_cpu(struct mdesc_handle *hp, u64 mp, int cpuid, void *arg)
{
    ncpus_probed++;
#ifdef CONFIG_SMP
    set_cpu_present(cpuid, true);
#endif
    return NULL;
}

void __cpuinit mdesc_populate_present_mask(cpumask_t *mask)
{
    if (tlb_type != hypervisor)
        return;

    ncpus_probed = 0;
    mdesc_iterate_over_cpus(record_one_cpu, NULL, mask);
}

static void * __init check_one_pgsz(struct mdesc_handle *hp, u64 mp, int cpuid, void *arg)
{
    const u64 *pgsz_prop = mdesc_get_property(hp, mp, "mmu-page-size-list", NULL);
    unsigned long *pgsz_mask = arg;
    u64 val;

    val = (HV_PGSZ_MASK_8K | HV_PGSZ_MASK_64K |
           HV_PGSZ_MASK_512K | HV_PGSZ_MASK_4MB);
    if (pgsz_prop)
        val = *pgsz_prop;

    if (!*pgsz_mask)
        *pgsz_mask = val;
    else
        *pgsz_mask &= val;
    return NULL;
}

void __init mdesc_get_page_sizes(cpumask_t *mask, unsigned long *pgsz_mask)
{
    *pgsz_mask = 0;
    mdesc_iterate_over_cpus(check_one_pgsz, pgsz_mask, mask);
}

static void * __cpuinit fill_in_one_cpu(struct mdesc_handle *hp, u64 mp, int cpuid, void *arg)
{
    const u64 *cfreq = mdesc_get_property(hp, mp, "clock-frequency", NULL);
    struct trap_per_cpu *tb;
    cpuinfo_sparc *c;
    u64 a;

#ifndef CONFIG_SMP
    /* On uniprocessor we only want the values for the
     * real physical cpu the kernel booted onto, however
     * cpu_data() only has one entry at index 0.
     */
    if (cpuid != real_hard_smp_processor_id())
        return NULL;
    cpuid = 0;
#endif

    c = &cpu_data(cpuid);
    c->clock_tick = *cfreq;

    tb = &trap_block[cpuid];
    get_mondo_data(hp, mp, tb);

    mdesc_for_each_arc(a, hp, mp, MDESC_ARC_TYPE_FWD) {
        u64 j, t = mdesc_arc_target(hp, a);
        const char *t_name;

        t_name = mdesc_node_name(hp, t);
        if (!strcmp(t_name, "cache")) {
            fill_in_one_cache(c, hp, t);
            continue;
        }

        mdesc_for_each_arc(j, hp, t, MDESC_ARC_TYPE_FWD) {
            u64 n = mdesc_arc_target(hp, j);
            const char *n_name;

            n_name = mdesc_node_name(hp, n);
            if (!strcmp(n_name, "cache"))
                fill_in_one_cache(c, hp, n);
        }
    }

    c->core_id = 0;
    c->proc_id = -1;

    return NULL;
}

void __cpuinit mdesc_fill_in_cpu_data(cpumask_t *mask)
{
    struct mdesc_handle *hp;

    mdesc_iterate_over_cpus(fill_in_one_cpu, NULL, mask);

#ifdef CONFIG_SMP
    sparc64_multi_core = 1;
#endif

    hp = mdesc_grab();

    set_core_ids(hp);
    set_proc_ids(hp);

    mdesc_release(hp);

    smp_fill_in_sib_core_maps();
}

static ssize_t mdesc_read(struct file *file, char __user *buf,
              size_t len, loff_t *offp)
{
    struct mdesc_handle *hp = mdesc_grab();
    int err;

    if (!hp)
        return -ENODEV;

    err = hp->handle_size;
    if (len < hp->handle_size)
        err = -EMSGSIZE;
    else if (copy_to_user(buf, &hp->mdesc, hp->handle_size))
        err = -EFAULT;
    mdesc_release(hp);

    return err;
}

static const struct file_operations mdesc_fops = {
    .read   = mdesc_read,
    .owner  = THIS_MODULE,
    .llseek = noop_llseek,
};

static struct miscdevice mdesc_misc = {
    .minor  = MISC_DYNAMIC_MINOR,
    .name   = "mdesc",
    .fops   = &mdesc_fops,
};

static int __init mdesc_misc_init(void)
{
    return misc_register(&mdesc_misc);
}

__initcall(mdesc_misc_init);

void __init sun4v_mdesc_init(void)
{
    struct mdesc_handle *hp;
    unsigned long len, real_len, status;

    (void) sun4v_mach_desc(0UL, 0UL, &len);

    printk("MDESC: Size is %lu bytes.\n", len);

    hp = mdesc_alloc(len, &memblock_mdesc_ops);
    if (hp == NULL) {
        prom_printf("MDESC: alloc of %lu bytes failed.\n", len);
        prom_halt();
    }

    status = sun4v_mach_desc(__pa(&hp->mdesc), len, &real_len);
    if (status != HV_EOK || real_len > len) {
        prom_printf("sun4v_mach_desc fails, err(%lu), "
                "len(%lu), real_len(%lu)\n",
                status, len, real_len);
        mdesc_free(hp);
        prom_halt();
    }

    cur_mdesc = hp;

    report_platform_properties();
}