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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 #include <asm/sstate.h>
  13
  14 /* If the hypervisor indicates that the API setting
  15  * calls are unsupported, by returning HV_EBADTRAP or
  16  * HV_ENOTSUPPORTED, we assume that API groups with the
  17  * PRE_API flag set are major 1 minor 0.
  18  */
  19 struct api_info {
  20         unsigned long group;
  21         unsigned long major;
  22         unsigned long minor;
  23         unsigned int refcnt;
  24         unsigned int flags;
  25 #define FLAG_PRE_API            0x00000001
  26 };
  27
  28 static struct api_info api_table[] = {
  29         { .group = HV_GRP_SUN4V,        .flags = FLAG_PRE_API   },
  30         { .group = HV_GRP_CORE,         .flags = FLAG_PRE_API   },
  31         { .group = HV_GRP_INTR,                                 },
  32         { .group = HV_GRP_SOFT_STATE,                           },
  33         { .group = HV_GRP_PCI,          .flags = FLAG_PRE_API   },
  34         { .group = HV_GRP_LDOM,                                 },
  35         { .group = HV_GRP_SVC_CHAN,     .flags = FLAG_PRE_API   },
  36         { .group = HV_GRP_NCS,          .flags = FLAG_PRE_API   },
  37         { .group = HV_GRP_NIAG_PERF,    .flags = FLAG_PRE_API   },
  38         { .group = HV_GRP_FIRE_PERF,                            },
  39         { .group = HV_GRP_DIAG,         .flags = FLAG_PRE_API   },
  40 };
  41
  42 static DEFINE_SPINLOCK(hvapi_lock);
  43
  44 static struct api_info *__get_info(unsigned long group)
  45 {
  46         int i;
  47
  48         for (i = 0; i < ARRAY_SIZE(api_table); i++) {
  49                 if (api_table[i].group == group)
  50                         return &api_table[i];
  51         }
  52         return NULL;
  53 }
  54
  55 static void __get_ref(struct api_info *p)
  56 {
  57         p->refcnt++;
  58 }
  59
  60 static void __put_ref(struct api_info *p)
  61 {
  62         if (--p->refcnt == 0) {
  63                 unsigned long ignore;
  64
  65                 sun4v_set_version(p->group, 0, 0, &ignore);
  66                 p->major = p->minor = 0;
  67         }
  68 }
  69
  70 /* Register a hypervisor API specification.  It indicates the
  71  * API group and desired major+minor.
  72  *
  73  * If an existing API registration exists '0' (success) will
  74  * be returned if it is compatible with the one being registered.
  75  * Otherwise a negative error code will be returned.
  76  *
  77  * Otherwise an attempt will be made to negotiate the requested
  78  * API group/major/minor with the hypervisor, and errors returned
  79  * if that does not succeed.
  80  */
  81 int sun4v_hvapi_register(unsigned long group, unsigned long major,
  82                          unsigned long *minor)
  83 {
  84         struct api_info *p;
  85         unsigned long flags;
  86         int ret;
  87
  88         spin_lock_irqsave(&hvapi_lock, flags);
  89         p = __get_info(group);
  90         ret = -EINVAL;
  91         if (p) {
  92                 if (p->refcnt) {
  93                         ret = -EINVAL;
  94                         if (p->major == major) {
  95                                 *minor = p->minor;
  96                                 ret = 0;
  97                         }
  98                 } else {
  99                         unsigned long actual_minor;
 100                         unsigned long hv_ret;
 101
 102                         hv_ret = sun4v_set_version(group, major, *minor,
 103                                                    &actual_minor);
 104                         ret = -EINVAL;
 105                         if (hv_ret == HV_EOK) {
 106                                 *minor = actual_minor;
 107                                 p->major = major;
 108                                 p->minor = actual_minor;
 109                                 ret = 0;
 110                         } else if (hv_ret == HV_EBADTRAP ||
 111                                    hv_ret == HV_ENOTSUPPORTED) {
 112                                 if (p->flags & FLAG_PRE_API) {
 113                                         if (major == 1) {
 114                                                 p->major = 1;
 115                                                 p->minor = 0;
 116                                                 *minor = 0;
 117                                                 ret = 0;
 118                                         }
 119                                 }
 120                         }
 121                 }
 122
 123                 if (ret == 0)
 124                         __get_ref(p);
 125         }
 126         spin_unlock_irqrestore(&hvapi_lock, flags);
 127
 128         return ret;
 129 }
 130 EXPORT_SYMBOL(sun4v_hvapi_register);
 131
 132 void sun4v_hvapi_unregister(unsigned long group)
 133 {
 134         struct api_info *p;
 135         unsigned long flags;
 136
 137         spin_lock_irqsave(&hvapi_lock, flags);
 138         p = __get_info(group);
 139         if (p)
 140                 __put_ref(p);
 141         spin_unlock_irqrestore(&hvapi_lock, flags);
 142 }
 143 EXPORT_SYMBOL(sun4v_hvapi_unregister);
 144
 145 int sun4v_hvapi_get(unsigned long group,
 146                     unsigned long *major,
 147                     unsigned long *minor)
 148 {
 149         struct api_info *p;
 150         unsigned long flags;
 151         int ret;
 152
 153         spin_lock_irqsave(&hvapi_lock, flags);
 154         ret = -EINVAL;
 155         p = __get_info(group);
 156         if (p && p->refcnt) {
 157                 *major = p->major;
 158                 *minor = p->minor;
 159                 ret = 0;
 160         }
 161         spin_unlock_irqrestore(&hvapi_lock, flags);
 162
 163         return ret;
 164 }
 165 EXPORT_SYMBOL(sun4v_hvapi_get);
 166
 167 void __init sun4v_hvapi_init(void)
 168 {
 169         unsigned long group, major, minor;
 170
 171         group = HV_GRP_SUN4V;
 172         major = 1;
 173         minor = 0;
 174         if (sun4v_hvapi_register(group, major, &minor))
 175                 goto bad;
 176
 177         group = HV_GRP_CORE;
 178         major = 1;
 179         minor = 1;
 180         if (sun4v_hvapi_register(group, major, &minor))
 181                 goto bad;
 182
 183         sun4v_sstate_init();
 184
 185         return;
 186
 187 bad:
 188         prom_printf("HVAPI: Cannot register API group "
 189                     "%lx with major(%u) minor(%u)\n",
 190                     group, major, minor);
 191         prom_halt();
 192 }