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mdesc.c

/* mdesc.c: Sun4V machine description handling.
 *
 * Copyright (C) 2007, 2008 David S. Miller <davem@davemloft.net>
 */
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/lmb.h>
#include <linux/log2.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>

#include <asm/hypervisor.h>
#include <asm/mdesc.h>
#include <asm/prom.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_lmb_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 = lmb_alloc(alloc_size, PAGE_SIZE);

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

static void mdesc_lmb_free(struct mdesc_handle *hp)
{
      unsigned int alloc_size, handle_size = hp->handle_size;
      unsigned long start, end;

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

      alloc_size = PAGE_ALIGN(handle_size);

      start = (unsigned long) hp;
      end = start + alloc_size;

      while (start < end) {
            struct page *p;

            p = virt_to_page(start);
            ClearPageReserved(p);
            __free_page(p);
            start += PAGE_SIZE;
      }
}

static struct mdesc_mem_ops lmb_mdesc_ops = {
      .alloc = mdesc_lmb_alloc,
      .free  = mdesc_lmb_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 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 [%08lx]\n", *v);
      v = mdesc_get_property(hp, pn, "serial#", NULL);
      if (v)
            printk("PLATFORM: serial# [%08lx]\n", *v);
      v = mdesc_get_property(hp, pn, "stick-frequency", NULL);
      printk("PLATFORM: stick-frequency [%08lx]\n", *v);
      v = mdesc_get_property(hp, pn, "mac-address", NULL);
      if (v)
            printk("PLATFORM: mac-address [%lx]\n", *v);
      v = mdesc_get_property(hp, pn, "watchdog-resolution", NULL);
      if (v)
            printk("PLATFORM: watchdog-resolution [%lu ms]\n", *v);
      v = mdesc_get_property(hp, pn, "watchdog-max-timeout", NULL);
      if (v)
            printk("PLATFORM: watchdog-max-timeout [%lu ms]\n", *v);
      v = mdesc_get_property(hp, pn, "max-cpus", NULL);
      if (v)
            printk("PLATFORM: max-cpus [%lu]\n", *v);

#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++)
                  cpu_set(i, cpu_possible_map);
      }
#endif

      mdesc_release(hp);
}

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

static void __devinit get_one_mondo_bits(const u64 *p, unsigned int *mask,
                               unsigned char def)
{
      u64 val;

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

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

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

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

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

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

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

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

      val = mdesc_get_property(hp, mp, "q-nonresumable-#bits", NULL);
      get_one_mondo_bits(val, &tb->nonresum_qmask, 2);
}

void __cpuinit mdesc_fill_in_cpu_data(cpumask_t mask)
{
      struct mdesc_handle *hp = mdesc_grab();
      u64 mp;

      ncpus_probed = 0;
      mdesc_for_each_node_by_name(hp, mp, "cpu") {
            const u64 *id = mdesc_get_property(hp, mp, "id", NULL);
            const u64 *cfreq = mdesc_get_property(hp, mp, "clock-frequency", NULL);
            struct trap_per_cpu *tb;
            cpuinfo_sparc *c;
            int cpuid;
            u64 a;

            ncpus_probed++;

            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 (!cpu_isset(cpuid, mask))
                  continue;
#else
            /* 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())
                  continue;
            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);
                  }
            }

#ifdef CONFIG_SMP
            cpu_set(cpuid, cpu_present_map);
#endif

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

#ifdef CONFIG_SMP
      sparc64_multi_core = 1;
#endif

      set_core_ids(hp);
      set_proc_ids(hp);

      smp_fill_in_sib_core_maps();

      mdesc_release(hp);
}

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,
};

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;
      cpumask_t mask;

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

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

      hp = mdesc_alloc(len, &lmb_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();

      cpus_setall(mask);
      mdesc_fill_in_cpu_data(mask);
}

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