hvapi.c

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/* hvapi.c: Hypervisor API management.
 *
 * Copyright (C) 2007 David S. Miller <[email protected]>
 */
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/init.h>

#include <asm/hypervisor.h>
#include <asm/oplib.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_TM,                   },
    { .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_PBOOT,                },
    { .group = HV_GRP_TPM,                  },
    { .group = HV_GRP_SDIO,                 },
    { .group = HV_GRP_SDIO_ERR,             },
    { .group = HV_GRP_REBOOT_DATA,              },
    { .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_KT_CPU,               },
    { .group = HV_GRP_VT_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;

    return;

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