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hvapi.c

/* hvapi.c: Hypervisor API management.
 *
 * Copyright (C) 2007 David S. Miller <davem@davemloft.net>
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>

#include <asm/hypervisor.h>
#include <asm/oplib.h>
#include <asm/sstate.h>

/* If the hypervisor indicates that the API setting
 * calls are unsupported, by returning HV_EBADTRAP or
 * HV_ENOTSUPPORTED, we assume that API groups with the
 * PRE_API flag set are major 1 minor 0.
 */
struct api_info {
      unsigned long group;
      unsigned long major;
      unsigned long minor;
      unsigned int refcnt;
      unsigned int flags;
#define FLAG_PRE_API          0x00000001
};

static struct api_info api_table[] = {
      { .group = HV_GRP_SUN4V,      .flags = FLAG_PRE_API   },
      { .group = HV_GRP_CORE,       .flags = FLAG_PRE_API   },
      { .group = HV_GRP_INTR,                         },
      { .group = HV_GRP_SOFT_STATE,                   },
      { .group = HV_GRP_PCI,        .flags = FLAG_PRE_API   },
      { .group = HV_GRP_LDOM,                         },
      { .group = HV_GRP_SVC_CHAN,   .flags = FLAG_PRE_API   },
      { .group = HV_GRP_NCS,        .flags = FLAG_PRE_API   },
      { .group = HV_GRP_RNG,                          },
      { .group = HV_GRP_NIAG_PERF,  .flags = FLAG_PRE_API   },
      { .group = HV_GRP_FIRE_PERF,                    },
      { .group = HV_GRP_N2_CPU,                       },
      { .group = HV_GRP_NIU,                          },
      { .group = HV_GRP_VF_CPU,                       },
      { .group = HV_GRP_DIAG,       .flags = FLAG_PRE_API   },
};

static DEFINE_SPINLOCK(hvapi_lock);

static struct api_info *__get_info(unsigned long group)
{
      int i;

      for (i = 0; i < ARRAY_SIZE(api_table); i++) {
            if (api_table[i].group == group)
                  return &api_table[i];
      }
      return NULL;
}

static void __get_ref(struct api_info *p)
{
      p->refcnt++;
}

static void __put_ref(struct api_info *p)
{
      if (--p->refcnt == 0) {
            unsigned long ignore;

            sun4v_set_version(p->group, 0, 0, &ignore);
            p->major = p->minor = 0;
      }
}

/* Register a hypervisor API specification.  It indicates the
 * API group and desired major+minor.
 *
 * If an existing API registration exists '0' (success) will
 * be returned if it is compatible with the one being registered.
 * Otherwise a negative error code will be returned.
 *
 * Otherwise an attempt will be made to negotiate the requested
 * API group/major/minor with the hypervisor, and errors returned
 * if that does not succeed.
 */
int sun4v_hvapi_register(unsigned long group, unsigned long major,
                   unsigned long *minor)
{
      struct api_info *p;
      unsigned long flags;
      int ret;

      spin_lock_irqsave(&hvapi_lock, flags);
      p = __get_info(group);
      ret = -EINVAL;
      if (p) {
            if (p->refcnt) {
                  ret = -EINVAL;
                  if (p->major == major) {
                        *minor = p->minor;
                        ret = 0;
                  }
            } else {
                  unsigned long actual_minor;
                  unsigned long hv_ret;

                  hv_ret = sun4v_set_version(group, major, *minor,
                                       &actual_minor);
                  ret = -EINVAL;
                  if (hv_ret == HV_EOK) {
                        *minor = actual_minor;
                        p->major = major;
                        p->minor = actual_minor;
                        ret = 0;
                  } else if (hv_ret == HV_EBADTRAP ||
                           hv_ret == HV_ENOTSUPPORTED) {
                        if (p->flags & FLAG_PRE_API) {
                              if (major == 1) {
                                    p->major = 1;
                                    p->minor = 0;
                                    *minor = 0;
                                    ret = 0;
                              }
                        }
                  }
            }

            if (ret == 0)
                  __get_ref(p);
      }
      spin_unlock_irqrestore(&hvapi_lock, flags);

      return ret;
}
EXPORT_SYMBOL(sun4v_hvapi_register);

void sun4v_hvapi_unregister(unsigned long group)
{
      struct api_info *p;
      unsigned long flags;

      spin_lock_irqsave(&hvapi_lock, flags);
      p = __get_info(group);
      if (p)
            __put_ref(p);
      spin_unlock_irqrestore(&hvapi_lock, flags);
}
EXPORT_SYMBOL(sun4v_hvapi_unregister);

int sun4v_hvapi_get(unsigned long group,
                unsigned long *major,
                unsigned long *minor)
{
      struct api_info *p;
      unsigned long flags;
      int ret;

      spin_lock_irqsave(&hvapi_lock, flags);
      ret = -EINVAL;
      p = __get_info(group);
      if (p && p->refcnt) {
            *major = p->major;
            *minor = p->minor;
            ret = 0;
      }
      spin_unlock_irqrestore(&hvapi_lock, flags);

      return ret;
}
EXPORT_SYMBOL(sun4v_hvapi_get);

void __init sun4v_hvapi_init(void)
{
      unsigned long group, major, minor;

      group = HV_GRP_SUN4V;
      major = 1;
      minor = 0;
      if (sun4v_hvapi_register(group, major, &minor))
            goto bad;

      group = HV_GRP_CORE;
      major = 1;
      minor = 1;
      if (sun4v_hvapi_register(group, major, &minor))
            goto bad;

      sun4v_sstate_init();

      return;

bad:
      prom_printf("HVAPI: Cannot register API group "
                "%lx with major(%u) minor(%u)\n",
                group, major, minor);
      prom_halt();
}

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