/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * (C) Copyright 2020 Hewlett Packard Enterprise Development LP
 * Copyright (C) 2004-2008 Silicon Graphics, Inc. All rights reserved.
 */

/*
 * External Cross Partition (XP) structures and defines.
 */

#ifndef _DRIVERS_MISC_SGIXP_XP_H
#define _DRIVERS_MISC_SGIXP_XP_H

#include <linux/mutex.h>

#if defined CONFIG_X86_UV || defined CONFIG_IA64_SGI_UV
#include <asm/uv/uv.h>
#endif

#ifdef USE_DBUG_ON
#define DBUG_ON(condition)      BUG_ON(condition)
#else
#define DBUG_ON(condition)
#endif

/*
 * Define the maximum number of partitions the system can possibly support.
 * It is based on the maximum number of hardware partitionable regions. The
 * term 'region' in this context refers to the minimum number of nodes that
 * can comprise an access protection grouping. The access protection is in
 * regards to memory, IPI and IOI.
 *
 * The maximum number of hardware partitionable regions is equal to the
 * maximum number of nodes in the entire system divided by the minimum number
 * of nodes that comprise an access protection grouping.
 */
#define XP_MAX_NPARTITIONS_SN2  64
#define XP_MAX_NPARTITIONS_UV   256

/*
 * XPC establishes channel connections between the local partition and any
 * other partition that is currently up. Over these channels, kernel-level
 * `users' can communicate with their counterparts on the other partitions.
 *
 * If the need for additional channels arises, one can simply increase
 * XPC_MAX_NCHANNELS accordingly. If the day should come where that number
 * exceeds the absolute MAXIMUM number of channels possible (eight), then one
 * will need to make changes to the XPC code to accommodate for this.
 *
 * The absolute maximum number of channels possible is limited to eight for
 * performance reasons on sn2 hardware. The internal cross partition structures
 * require sixteen bytes per channel, and eight allows all of this
 * interface-shared info to fit in one 128-byte cacheline.
 */
#define XPC_MEM_CHANNEL         0       /* memory channel number */
#define XPC_NET_CHANNEL         1       /* network channel number */

#define XPC_MAX_NCHANNELS       2       /* max #of channels allowed */

#if XPC_MAX_NCHANNELS > 8
#error  XPC_MAX_NCHANNELS exceeds absolute MAXIMUM possible.
#endif

/*
 * Define macro, XPC_MSG_SIZE(), is provided for the user
 * that wants to fit as many msg entries as possible in a given memory size
 * (e.g. a memory page).
 */
#define XPC_MSG_MAX_SIZE        128
#define XPC_MSG_HDR_MAX_SIZE    16
#define XPC_MSG_PAYLOAD_MAX_SIZE (XPC_MSG_MAX_SIZE - XPC_MSG_HDR_MAX_SIZE)

#define XPC_MSG_SIZE(_payload_size) \
                                ALIGN(XPC_MSG_HDR_MAX_SIZE + (_payload_size), \
                                      is_uv_system() ? 64 : 128)


/*
 * Define the return values and values passed to user's callout functions.
 * (It is important to add new value codes at the end just preceding
 * xpUnknownReason, which must have the highest numerical value.)
 */
enum xp_retval {
        xpSuccess = 0,

        xpNotConnected,         /*  1: channel is not connected */
        xpConnected,            /*  2: channel connected (opened) */
        xpRETIRED1,             /*  3: (formerly xpDisconnected) */

        xpMsgReceived,          /*  4: message received */
        xpMsgDelivered,         /*  5: message delivered and acknowledged */

        xpRETIRED2,             /*  6: (formerly xpTransferFailed) */

        xpNoWait,               /*  7: operation would require wait */
        xpRetry,                /*  8: retry operation */
        xpTimeout,              /*  9: timeout in xpc_allocate_msg_wait() */
        xpInterrupted,          /* 10: interrupted wait */

        xpUnequalMsgSizes,      /* 11: message size disparity between sides */
        xpInvalidAddress,       /* 12: invalid address */

        xpNoMemory,             /* 13: no memory available for XPC structures */
        xpLackOfResources,      /* 14: insufficient resources for operation */
        xpUnregistered,         /* 15: channel is not registered */
        xpAlreadyRegistered,    /* 16: channel is already registered */

        xpPartitionDown,        /* 17: remote partition is down */
        xpNotLoaded,            /* 18: XPC module is not loaded */
        xpUnloading,            /* 19: this side is unloading XPC module */

        xpBadMagic,             /* 20: XPC MAGIC string not found */

        xpReactivating,         /* 21: remote partition was reactivated */

        xpUnregistering,        /* 22: this side is unregistering channel */
        xpOtherUnregistering,   /* 23: other side is unregistering channel */

        xpCloneKThread,         /* 24: cloning kernel thread */
        xpCloneKThreadFailed,   /* 25: cloning kernel thread failed */

        xpNoHeartbeat,          /* 26: remote partition has no heartbeat */

        xpPioReadError,         /* 27: PIO read error */
        xpPhysAddrRegFailed,    /* 28: registration of phys addr range failed */

        xpRETIRED3,             /* 29: (formerly xpBteDirectoryError) */
        xpRETIRED4,             /* 30: (formerly xpBtePoisonError) */
        xpRETIRED5,             /* 31: (formerly xpBteWriteError) */
        xpRETIRED6,             /* 32: (formerly xpBteAccessError) */
        xpRETIRED7,             /* 33: (formerly xpBtePWriteError) */
        xpRETIRED8,             /* 34: (formerly xpBtePReadError) */
        xpRETIRED9,             /* 35: (formerly xpBteTimeOutError) */
        xpRETIRED10,            /* 36: (formerly xpBteXtalkError) */
        xpRETIRED11,            /* 37: (formerly xpBteNotAvailable) */
        xpRETIRED12,            /* 38: (formerly xpBteUnmappedError) */

        xpBadVersion,           /* 39: bad version number */
        xpVarsNotSet,           /* 40: the XPC variables are not set up */
        xpNoRsvdPageAddr,       /* 41: unable to get rsvd page's phys addr */
        xpInvalidPartid,        /* 42: invalid partition ID */
        xpLocalPartid,          /* 43: local partition ID */

        xpOtherGoingDown,       /* 44: other side going down, reason unknown */
        xpSystemGoingDown,      /* 45: system is going down, reason unknown */
        xpSystemHalt,           /* 46: system is being halted */
        xpSystemReboot,         /* 47: system is being rebooted */
        xpSystemPoweroff,       /* 48: system is being powered off */

        xpDisconnecting,        /* 49: channel disconnecting (closing) */

        xpOpenCloseError,       /* 50: channel open/close protocol error */

        xpDisconnected,         /* 51: channel disconnected (closed) */

        xpBteCopyError,         /* 52: bte_copy() returned error */
        xpSalError,             /* 53: sn SAL error */
        xpRsvdPageNotSet,       /* 54: the reserved page is not set up */
        xpPayloadTooBig,        /* 55: payload too large for message slot */

        xpUnsupported,          /* 56: unsupported functionality or resource */
        xpNeedMoreInfo,         /* 57: more info is needed by SAL */

        xpGruCopyError,         /* 58: gru_copy_gru() returned error */
        xpGruSendMqError,       /* 59: gru send message queue related error */

        xpBadChannelNumber,     /* 60: invalid channel number */
        xpBadMsgType,           /* 61: invalid message type */
        xpBiosError,            /* 62: BIOS error */

        xpUnknownReason         /* 63: unknown reason - must be last in enum */
};

/*
 * Define the callout function type used by XPC to update the user on
 * connection activity and state changes via the user function registered
 * by xpc_connect().
 *
 * Arguments:
 *
 *      reason - reason code.
 *      partid - partition ID associated with condition.
 *      ch_number - channel # associated with condition.
 *      data - pointer to optional data.
 *      key - pointer to optional user-defined value provided as the "key"
 *            argument to xpc_connect().
 *
 * A reason code of xpConnected indicates that a connection has been
 * established to the specified partition on the specified channel. The data
 * argument indicates the max number of entries allowed in the message queue.
 *
 * A reason code of xpMsgReceived indicates that a XPC message arrived from
 * the specified partition on the specified channel. The data argument
 * specifies the address of the message's payload. The user must call
 * xpc_received() when finished with the payload.
 *
 * All other reason codes indicate failure. The data argmument is NULL.
 * When a failure reason code is received, one can assume that the channel
 * is not connected.
 */
typedef void (*xpc_channel_func) (enum xp_retval reason, short partid,
                                  int ch_number, void *data, void *key);

/*
 * Define the callout function type used by XPC to notify the user of
 * messages received and delivered via the user function registered by
 * xpc_send_notify().
 *
 * Arguments:
 *
 *      reason - reason code.
 *      partid - partition ID associated with condition.
 *      ch_number - channel # associated with condition.
 *      key - pointer to optional user-defined value provided as the "key"
 *            argument to xpc_send_notify().
 *
 * A reason code of xpMsgDelivered indicates that the message was delivered
 * to the intended recipient and that they have acknowledged its receipt by
 * calling xpc_received().
 *
 * All other reason codes indicate failure.
 *
 * NOTE: The user defined function must be callable by an interrupt handler
 *       and thus cannot block.
 */
typedef void (*xpc_notify_func) (enum xp_retval reason, short partid,
                                 int ch_number, void *key);

/*
 * The following is a registration entry. There is a global array of these,
 * one per channel. It is used to record the connection registration made
 * by the users of XPC. As long as a registration entry exists, for any
 * partition that comes up, XPC will attempt to establish a connection on
 * that channel. Notification that a connection has been made will occur via
 * the xpc_channel_func function.
 *
 * The 'func' field points to the function to call when aynchronous
 * notification is required for such events as: a connection established/lost,
 * or an incoming message received, or an error condition encountered. A
 * non-NULL 'func' field indicates that there is an active registration for
 * the channel.
 */
struct xpc_registration {
        struct mutex mutex;
        xpc_channel_func func;  /* function to call */
        void *key;              /* pointer to user's key */
        u16 nentries;           /* #of msg entries in local msg queue */
        u16 entry_size;         /* message queue's message entry size */
        u32 assigned_limit;     /* limit on #of assigned kthreads */
        u32 idle_limit;         /* limit on #of idle kthreads */
} ____cacheline_aligned;

#define XPC_CHANNEL_REGISTERED(_c)      (xpc_registrations[_c].func != NULL)

/* the following are valid xpc_send() or xpc_send_notify() flags */
#define XPC_WAIT        0       /* wait flag */
#define XPC_NOWAIT      1       /* no wait flag */

struct xpc_interface {
        void (*connect) (int);
        void (*disconnect) (int);
        enum xp_retval (*send) (short, int, u32, void *, u16);
        enum xp_retval (*send_notify) (short, int, u32, void *, u16,
                                        xpc_notify_func, void *);
        void (*received) (short, int, void *);
        enum xp_retval (*partid_to_nasids) (short, void *);
};

extern struct xpc_interface xpc_interface;

extern void xpc_set_interface(void (*)(int),
                              void (*)(int),
                              enum xp_retval (*)(short, int, u32, void *, u16),
                              enum xp_retval (*)(short, int, u32, void *, u16,
                                                 xpc_notify_func, void *),
                              void (*)(short, int, void *),
                              enum xp_retval (*)(short, void *));
extern void xpc_clear_interface(void);

extern enum xp_retval xpc_connect(int, xpc_channel_func, void *, u16,
                                   u16, u32, u32);
extern void xpc_disconnect(int);

static inline enum xp_retval
xpc_send(short partid, int ch_number, u32 flags, void *payload,
         u16 payload_size)
{
        if (!xpc_interface.send)
                return xpNotLoaded;

        return xpc_interface.send(partid, ch_number, flags, payload,
                                  payload_size);
}

static inline enum xp_retval
xpc_send_notify(short partid, int ch_number, u32 flags, void *payload,
                u16 payload_size, xpc_notify_func func, void *key)
{
        if (!xpc_interface.send_notify)
                return xpNotLoaded;

        return xpc_interface.send_notify(partid, ch_number, flags, payload,
                                         payload_size, func, key);
}

static inline void
xpc_received(short partid, int ch_number, void *payload)
{
        if (xpc_interface.received)
                xpc_interface.received(partid, ch_number, payload);
}

static inline enum xp_retval
xpc_partid_to_nasids(short partid, void *nasids)
{
        if (!xpc_interface.partid_to_nasids)
                return xpNotLoaded;

        return xpc_interface.partid_to_nasids(partid, nasids);
}

extern short xp_max_npartitions;
extern short xp_partition_id;
extern u8 xp_region_size;

extern unsigned long (*xp_pa) (void *);
extern unsigned long (*xp_socket_pa) (unsigned long);
extern enum xp_retval (*xp_remote_memcpy) (unsigned long, const unsigned long,
                       size_t);
extern int (*xp_cpu_to_nasid) (int);
extern enum xp_retval (*xp_expand_memprotect) (unsigned long, unsigned long);
extern enum xp_retval (*xp_restrict_memprotect) (unsigned long, unsigned long);

extern u64 xp_nofault_PIOR_target;
extern int xp_nofault_PIOR(void *);
extern int xp_error_PIOR(void);

extern struct device *xp;
extern enum xp_retval xp_init_uv(void);
extern void xp_exit_uv(void);

#endif /* _DRIVERS_MISC_SGIXP_XP_H */