// SPDX-License-Identifier: GPL-2.0
/* hvapi.c: Hypervisor API management.
 *
 * Copyright (C) 2007 David S. Miller <davem@davemloft.net>
 */
#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_ATU,          .flags = FLAG_PRE_API   },
        { .group = HV_GRP_DAX,                                  },
        { .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_T5_CPU,                               },
        { .group = HV_GRP_DIAG,         .flags = FLAG_PRE_API   },
        { .group = HV_GRP_M7_PERF,                              },
};

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 = 6;
        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();
}