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   1 /* hvapi.c: Hypervisor API management.
   2  *
   3  * Copyright (C) 2007 David S. Miller <davem@davemloft.net>
   4  */
   5 #include <linux/kernel.h>
   6 #include <linux/module.h>
   7 #include <linux/init.h>
   8 #include <linux/slab.h>
   9
  10 #include <asm/hypervisor.h>
  11 #include <asm/oplib.h>
  12
  13 /* If the hypervisor indicates that the API setting
  14  * calls are unsupported, by returning HV_EBADTRAP or
  15  * HV_ENOTSUPPORTED, we assume that API groups with the
  16  * PRE_API flag set are major 1 minor 0.
  17  */
  18 struct api_info {
  19         unsigned long group;
  20         unsigned long major;
  21         unsigned long minor;
  22         unsigned int refcnt;
  23         unsigned int flags;
  24 #define FLAG_PRE_API            0x00000001
  25 };
  26
  27 static struct api_info api_table[] = {
  28         { .group = HV_GRP_SUN4V,        .flags = FLAG_PRE_API   },
  29         { .group = HV_GRP_CORE,         .flags = FLAG_PRE_API   },
  30         { .group = HV_GRP_INTR,                                 },
  31         { .group = HV_GRP_SOFT_STATE,                           },
  32         { .group = HV_GRP_PCI,          .flags = FLAG_PRE_API   },
  33         { .group = HV_GRP_LDOM,                                 },
  34         { .group = HV_GRP_SVC_CHAN,     .flags = FLAG_PRE_API   },
  35         { .group = HV_GRP_NCS,          .flags = FLAG_PRE_API   },
  36         { .group = HV_GRP_RNG,                                  },
  37         { .group = HV_GRP_NIAG_PERF,    .flags = FLAG_PRE_API   },
  38         { .group = HV_GRP_FIRE_PERF,                            },
  39         { .group = HV_GRP_N2_CPU,                               },
  40         { .group = HV_GRP_NIU,                                  },
  41         { .group = HV_GRP_VF_CPU,                               },
  42         { .group = HV_GRP_DIAG,         .flags = FLAG_PRE_API   },
  43 };
  44
  45 static DEFINE_SPINLOCK(hvapi_lock);
  46
  47 static struct api_info *__get_info(unsigned long group)
  48 {
  49         int i;
  50
  51         for (i = 0; i < ARRAY_SIZE(api_table); i++) {
  52                 if (api_table[i].group == group)
  53                         return &api_table[i];
  54         }
  55         return NULL;
  56 }
  57
  58 static void __get_ref(struct api_info *p)
  59 {
  60         p->refcnt++;
  61 }
  62
  63 static void __put_ref(struct api_info *p)
  64 {
  65         if (--p->refcnt == 0) {
  66                 unsigned long ignore;
  67
  68                 sun4v_set_version(p->group, 0, 0, &ignore);
  69                 p->major = p->minor = 0;
  70         }
  71 }
  72
  73 /* Register a hypervisor API specification.  It indicates the
  74  * API group and desired major+minor.
  75  *
  76  * If an existing API registration exists '0' (success) will
  77  * be returned if it is compatible with the one being registered.
  78  * Otherwise a negative error code will be returned.
  79  *
  80  * Otherwise an attempt will be made to negotiate the requested
  81  * API group/major/minor with the hypervisor, and errors returned
  82  * if that does not succeed.
  83  */
  84 int sun4v_hvapi_register(unsigned long group, unsigned long major,
  85                          unsigned long *minor)
  86 {
  87         struct api_info *p;
  88         unsigned long flags;
  89         int ret;
  90
  91         spin_lock_irqsave(&hvapi_lock, flags);
  92         p = __get_info(group);
  93         ret = -EINVAL;
  94         if (p) {
  95                 if (p->refcnt) {
  96                         ret = -EINVAL;
  97                         if (p->major == major) {
  98                                 *minor = p->minor;
  99                                 ret = 0;
 100                         }
 101                 } else {
 102                         unsigned long actual_minor;
 103                         unsigned long hv_ret;
 104
 105                         hv_ret = sun4v_set_version(group, major, *minor,
 106                                                    &actual_minor);
 107                         ret = -EINVAL;
 108                         if (hv_ret == HV_EOK) {
 109                                 *minor = actual_minor;
 110                                 p->major = major;
 111                                 p->minor = actual_minor;
 112                                 ret = 0;
 113                         } else if (hv_ret == HV_EBADTRAP ||
 114                                    hv_ret == HV_ENOTSUPPORTED) {
 115                                 if (p->flags & FLAG_PRE_API) {
 116                                         if (major == 1) {
 117                                                 p->major = 1;
 118                                                 p->minor = 0;
 119                                                 *minor = 0;
 120                                                 ret = 0;
 121                                         }
 122                                 }
 123                         }
 124                 }
 125
 126                 if (ret == 0)
 127                         __get_ref(p);
 128         }
 129         spin_unlock_irqrestore(&hvapi_lock, flags);
 130
 131         return ret;
 132 }
 133 EXPORT_SYMBOL(sun4v_hvapi_register);
 134
 135 void sun4v_hvapi_unregister(unsigned long group)
 136 {
 137         struct api_info *p;
 138         unsigned long flags;
 139
 140         spin_lock_irqsave(&hvapi_lock, flags);
 141         p = __get_info(group);
 142         if (p)
 143                 __put_ref(p);
 144         spin_unlock_irqrestore(&hvapi_lock, flags);
 145 }
 146 EXPORT_SYMBOL(sun4v_hvapi_unregister);
 147
 148 int sun4v_hvapi_get(unsigned long group,
 149                     unsigned long *major,
 150                     unsigned long *minor)
 151 {
 152         struct api_info *p;
 153         unsigned long flags;
 154         int ret;
 155
 156         spin_lock_irqsave(&hvapi_lock, flags);
 157         ret = -EINVAL;
 158         p = __get_info(group);
 159         if (p && p->refcnt) {
 160                 *major = p->major;
 161                 *minor = p->minor;
 162                 ret = 0;
 163         }
 164         spin_unlock_irqrestore(&hvapi_lock, flags);
 165
 166         return ret;
 167 }
 168 EXPORT_SYMBOL(sun4v_hvapi_get);
 169
 170 void __init sun4v_hvapi_init(void)
 171 {
 172         unsigned long group, major, minor;
 173
 174         group = HV_GRP_SUN4V;
 175         major = 1;
 176         minor = 0;
 177         if (sun4v_hvapi_register(group, major, &minor))
 178                 goto bad;
 179
 180         group = HV_GRP_CORE;
 181         major = 1;
 182         minor = 1;
 183         if (sun4v_hvapi_register(group, major, &minor))
 184                 goto bad;
 185
 186         return;
 187
 188 bad:
 189         prom_printf("HVAPI: Cannot register API group "
 190                     "%lx with major(%u) minor(%u)\n",
 191                     group, major, minor);
 192         prom_halt();
 193 }