sgi-xp: support runtime selection of xp_max_npartitions

[linux-2.6-omap-h63xx.git] / drivers / misc / sgi-xp / xpc.h

/*
 * 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.
 *
 * Copyright (c) 2004-2008 Silicon Graphics, Inc.  All Rights Reserved.
 */

/*
 * Cross Partition Communication (XPC) structures and macros.
 */

#ifndef _DRIVERS_MISC_SGIXP_XPC_H
#define _DRIVERS_MISC_SGIXP_XPC_H

#include <linux/interrupt.h>
#include <linux/sysctl.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/completion.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/sn/bte.h>
#include <asm/sn/clksupport.h>
#include <asm/sn/addrs.h>
#include <asm/sn/mspec.h>
#include <asm/sn/shub_mmr.h>
#include "xp.h"

/*
 * XPC Version numbers consist of a major and minor number. XPC can always
 * talk to versions with same major #, and never talk to versions with a
 * different major #.
 */
#define _XPC_VERSION(_maj, _min)        (((_maj) << 4) | ((_min) & 0xf))
#define XPC_VERSION_MAJOR(_v)           ((_v) >> 4)
#define XPC_VERSION_MINOR(_v)           ((_v) & 0xf)

/*
 * The next macros define word or bit representations for given
 * C-brick nasid in either the SAL provided bit array representing
 * nasids in the partition/machine or the AMO_t array used for
 * inter-partition initiation communications.
 *
 * For SN2 machines, C-Bricks are alway even numbered NASIDs.  As
 * such, some space will be saved by insisting that nasid information
 * passed from SAL always be packed for C-Bricks and the
 * cross-partition interrupts use the same packing scheme.
 */
#define XPC_NASID_W_INDEX(_n)   (((_n) / 64) / 2)
#define XPC_NASID_B_INDEX(_n)   (((_n) / 2) & (64 - 1))
#define XPC_NASID_IN_ARRAY(_n, _p) ((_p)[XPC_NASID_W_INDEX(_n)] & \
                                    (1UL << XPC_NASID_B_INDEX(_n)))
#define XPC_NASID_FROM_W_B(_w, _b) (((_w) * 64 + (_b)) * 2)

#define XPC_HB_DEFAULT_INTERVAL         5       /* incr HB every x secs */
#define XPC_HB_CHECK_DEFAULT_INTERVAL   20      /* check HB every x secs */

/* define the process name of HB checker and the CPU it is pinned to */
#define XPC_HB_CHECK_THREAD_NAME        "xpc_hb"
#define XPC_HB_CHECK_CPU                0

/* define the process name of the discovery thread */
#define XPC_DISCOVERY_THREAD_NAME       "xpc_discovery"

/*
 * the reserved page
 *
 *   SAL reserves one page of memory per partition for XPC. Though a full page
 *   in length (16384 bytes), its starting address is not page aligned, but it
 *   is cacheline aligned. The reserved page consists of the following:
 *
 *   reserved page header
 *
 *     The first cacheline of the reserved page contains the header
 *     (struct xpc_rsvd_page). Before SAL initialization has completed,
 *     SAL has set up the following fields of the reserved page header:
 *     SAL_signature, SAL_version, partid, and nasids_size. The other
 *     fields are set up by XPC. (xpc_rsvd_page points to the local
 *     partition's reserved page.)
 *
 *   part_nasids mask
 *   mach_nasids mask
 *
 *     SAL also sets up two bitmaps (or masks), one that reflects the actual
 *     nasids in this partition (part_nasids), and the other that reflects
 *     the actual nasids in the entire machine (mach_nasids). We're only
 *     interested in the even numbered nasids (which contain the processors
 *     and/or memory), so we only need half as many bits to represent the
 *     nasids. The part_nasids mask is located starting at the first cacheline
 *     following the reserved page header. The mach_nasids mask follows right
 *     after the part_nasids mask. The size in bytes of each mask is reflected
 *     by the reserved page header field 'nasids_size'. (Local partition's
 *     mask pointers are xpc_part_nasids and xpc_mach_nasids.)
 *
 *   vars
 *   vars part
 *
 *     Immediately following the mach_nasids mask are the XPC variables
 *     required by other partitions. First are those that are generic to all
 *     partitions (vars), followed on the next available cacheline by those
 *     which are partition specific (vars part). These are setup by XPC.
 *     (Local partition's vars pointers are xpc_vars and xpc_vars_part.)
 *
 * Note: Until vars_pa is set, the partition XPC code has not been initialized.
 */
struct xpc_rsvd_page {
        u64 SAL_signature;      /* SAL: unique signature */
        u64 SAL_version;        /* SAL: version */
        u8 partid;              /* SAL: partition ID */
        u8 version;
        u8 pad1[6];             /* align to next u64 in cacheline */
        u64 vars_pa;            /* physical address of struct xpc_vars */
        struct timespec stamp;  /* time when reserved page was setup by XPC */
        u64 pad2[9];            /* align to last u64 in cacheline */
        u64 nasids_size;        /* SAL: size of each nasid mask in bytes */
};

#define XPC_RP_VERSION _XPC_VERSION(1, 1) /* version 1.1 of the reserved page */

#define XPC_SUPPORTS_RP_STAMP(_version) \
                        (_version >= _XPC_VERSION(1, 1))

/*
 * compare stamps - the return value is:
 *
 *      < 0,    if stamp1 < stamp2
 *      = 0,    if stamp1 == stamp2
 *      > 0,    if stamp1 > stamp2
 */
static inline int
xpc_compare_stamps(struct timespec *stamp1, struct timespec *stamp2)
{
        int ret;

        ret = stamp1->tv_sec - stamp2->tv_sec;
        if (ret == 0)
                ret = stamp1->tv_nsec - stamp2->tv_nsec;

        return ret;
}

/*
 * Define the structures by which XPC variables can be exported to other
 * partitions. (There are two: struct xpc_vars and struct xpc_vars_part)
 */

/*
 * The following structure describes the partition generic variables
 * needed by other partitions in order to properly initialize.
 *
 * struct xpc_vars version number also applies to struct xpc_vars_part.
 * Changes to either structure and/or related functionality should be
 * reflected by incrementing either the major or minor version numbers
 * of struct xpc_vars.
 */
struct xpc_vars {
        u8 version;
        u64 heartbeat;
        u64 heartbeating_to_mask;
        u64 heartbeat_offline;  /* if 0, heartbeat should be changing */
        int act_nasid;
        int act_phys_cpuid;
        u64 vars_part_pa;
        u64 amos_page_pa;       /* paddr of page of AMOs from MSPEC driver */
        AMO_t *amos_page;       /* vaddr of page of AMOs from MSPEC driver */
};

#define XPC_V_VERSION _XPC_VERSION(3, 1)    /* version 3.1 of the cross vars */

#define XPC_SUPPORTS_DISENGAGE_REQUEST(_version) \
                        (_version >= _XPC_VERSION(3, 1))

static inline int
xpc_hb_allowed(short partid, struct xpc_vars *vars)
{
        return ((vars->heartbeating_to_mask & (1UL << partid)) != 0);
}

static inline void
xpc_allow_hb(short partid, struct xpc_vars *vars)
{
        u64 old_mask, new_mask;

        do {
                old_mask = vars->heartbeating_to_mask;
                new_mask = (old_mask | (1UL << partid));
        } while (cmpxchg(&vars->heartbeating_to_mask, old_mask, new_mask) !=
                 old_mask);
}

static inline void
xpc_disallow_hb(short partid, struct xpc_vars *vars)
{
        u64 old_mask, new_mask;

        do {
                old_mask = vars->heartbeating_to_mask;
                new_mask = (old_mask & ~(1UL << partid));
        } while (cmpxchg(&vars->heartbeating_to_mask, old_mask, new_mask) !=
                 old_mask);
}

/*
 * The AMOs page consists of a number of AMO variables which are divided into
 * four groups, The first two groups are used to identify an IRQ's sender.
 * These two groups consist of 64 and 128 AMO variables respectively. The last
 * two groups, consisting of just one AMO variable each, are used to identify
 * the remote partitions that are currently engaged (from the viewpoint of
 * the XPC running on the remote partition).
 */
#define XPC_NOTIFY_IRQ_AMOS        0
#define XPC_ACTIVATE_IRQ_AMOS      (XPC_NOTIFY_IRQ_AMOS + XP_MAX_NPARTITIONS_SN2)
#define XPC_ENGAGED_PARTITIONS_AMO (XPC_ACTIVATE_IRQ_AMOS + XP_NASID_MASK_WORDS)
#define XPC_DISENGAGE_REQUEST_AMO  (XPC_ENGAGED_PARTITIONS_AMO + 1)

/*
 * The following structure describes the per partition specific variables.
 *
 * An array of these structures, one per partition, will be defined. As a
 * partition becomes active XPC will copy the array entry corresponding to
 * itself from that partition. It is desirable that the size of this
 * structure evenly divide into a cacheline, such that none of the entries
 * in this array crosses a cacheline boundary. As it is now, each entry
 * occupies half a cacheline.
 */
struct xpc_vars_part {
        u64 magic;

        u64 openclose_args_pa;  /* physical address of open and close args */
        u64 GPs_pa;             /* physical address of Get/Put values */

        u64 IPI_amo_pa;         /* physical address of IPI AMO_t structure */
        int IPI_nasid;          /* nasid of where to send IPIs */
        int IPI_phys_cpuid;     /* physical CPU ID of where to send IPIs */

        u8 nchannels;           /* #of defined channels supported */

        u8 reserved[23];        /* pad to a full 64 bytes */
};

/*
 * The vars_part MAGIC numbers play a part in the first contact protocol.
 *
 * MAGIC1 indicates that the per partition specific variables for a remote
 * partition have been initialized by this partition.
 *
 * MAGIC2 indicates that this partition has pulled the remote partititions
 * per partition variables that pertain to this partition.
 */
#define XPC_VP_MAGIC1   0x0053524156435058L   /* 'XPCVARS\0'L (little endian) */
#define XPC_VP_MAGIC2   0x0073726176435058L   /* 'XPCvars\0'L (little endian) */

/* the reserved page sizes and offsets */

#define XPC_RP_HEADER_SIZE      L1_CACHE_ALIGN(sizeof(struct xpc_rsvd_page))
#define XPC_RP_VARS_SIZE        L1_CACHE_ALIGN(sizeof(struct xpc_vars))

#define XPC_RP_PART_NASIDS(_rp) ((u64 *)((u8 *)(_rp) + XPC_RP_HEADER_SIZE))
#define XPC_RP_MACH_NASIDS(_rp) (XPC_RP_PART_NASIDS(_rp) + xp_nasid_mask_words)
#define XPC_RP_VARS(_rp)        ((struct xpc_vars *)(XPC_RP_MACH_NASIDS(_rp) + \
                                    xp_nasid_mask_words))
#define XPC_RP_VARS_PART(_rp)   ((struct xpc_vars_part *) \
                                    ((u8 *)XPC_RP_VARS(_rp) + XPC_RP_VARS_SIZE))

/*
 * Functions registered by add_timer() or called by kernel_thread() only
 * allow for a single 64-bit argument. The following macros can be used to
 * pack and unpack two (32-bit, 16-bit or 8-bit) arguments into or out from
 * the passed argument.
 */
#define XPC_PACK_ARGS(_arg1, _arg2) \
                        ((((u64) _arg1) & 0xffffffff) | \
                        ((((u64) _arg2) & 0xffffffff) << 32))

#define XPC_UNPACK_ARG1(_args)  (((u64) _args) & 0xffffffff)
#define XPC_UNPACK_ARG2(_args)  ((((u64) _args) >> 32) & 0xffffffff)

/*
 * Define a Get/Put value pair (pointers) used with a message queue.
 */
struct xpc_gp {
        s64 get;                /* Get value */
        s64 put;                /* Put value */
};

#define XPC_GP_SIZE \
                L1_CACHE_ALIGN(sizeof(struct xpc_gp) * XPC_MAX_NCHANNELS)

/*
 * Define a structure that contains arguments associated with opening and
 * closing a channel.
 */
struct xpc_openclose_args {
        u16 reason;             /* reason why channel is closing */
        u16 msg_size;           /* sizeof each message entry */
        u16 remote_nentries;    /* #of message entries in remote msg queue */
        u16 local_nentries;     /* #of message entries in local msg queue */
        u64 local_msgqueue_pa;  /* physical address of local message queue */
};

#define XPC_OPENCLOSE_ARGS_SIZE \
              L1_CACHE_ALIGN(sizeof(struct xpc_openclose_args) * \
              XPC_MAX_NCHANNELS)

/* struct xpc_msg flags */

#define XPC_M_DONE              0x01    /* msg has been received/consumed */
#define XPC_M_READY             0x02    /* msg is ready to be sent */
#define XPC_M_INTERRUPT         0x04    /* send interrupt when msg consumed */

#define XPC_MSG_ADDRESS(_payload) \
                ((struct xpc_msg *)((u8 *)(_payload) - XPC_MSG_PAYLOAD_OFFSET))

/*
 * Defines notify entry.
 *
 * This is used to notify a message's sender that their message was received
 * and consumed by the intended recipient.
 */
struct xpc_notify {
        u8 type;                /* type of notification */

        /* the following two fields are only used if type == XPC_N_CALL */
        xpc_notify_func func;   /* user's notify function */
        void *key;              /* pointer to user's key */
};

/* struct xpc_notify type of notification */

#define XPC_N_CALL              0x01    /* notify function provided by user */

/*
 * Define the structure that manages all the stuff required by a channel. In
 * particular, they are used to manage the messages sent across the channel.
 *
 * This structure is private to a partition, and is NOT shared across the
 * partition boundary.
 *
 * There is an array of these structures for each remote partition. It is
 * allocated at the time a partition becomes active. The array contains one
 * of these structures for each potential channel connection to that partition.
 *
 * Each of these structures manages two message queues (circular buffers).
 * They are allocated at the time a channel connection is made. One of
 * these message queues (local_msgqueue) holds the locally created messages
 * that are destined for the remote partition. The other of these message
 * queues (remote_msgqueue) is a locally cached copy of the remote partition's
 * own local_msgqueue.
 *
 * The following is a description of the Get/Put pointers used to manage these
 * two message queues. Consider the local_msgqueue to be on one partition
 * and the remote_msgqueue to be its cached copy on another partition. A
 * description of what each of the lettered areas contains is included.
 *
 *
 *                     local_msgqueue      remote_msgqueue
 *
 *                        |/////////|      |/////////|
 *    w_remote_GP.get --> +---------+      |/////////|
 *                        |    F    |      |/////////|
 *     remote_GP.get  --> +---------+      +---------+ <-- local_GP->get
 *                        |         |      |         |
 *                        |         |      |    E    |
 *                        |         |      |         |
 *                        |         |      +---------+ <-- w_local_GP.get
 *                        |    B    |      |/////////|
 *                        |         |      |////D////|
 *                        |         |      |/////////|
 *                        |         |      +---------+ <-- w_remote_GP.put
 *                        |         |      |////C////|
 *      local_GP->put --> +---------+      +---------+ <-- remote_GP.put
 *                        |         |      |/////////|
 *                        |    A    |      |/////////|
 *                        |         |      |/////////|
 *     w_local_GP.put --> +---------+      |/////////|
 *                        |/////////|      |/////////|
 *
 *
 *          ( remote_GP.[get|put] are cached copies of the remote
 *            partition's local_GP->[get|put], and thus their values can
 *            lag behind their counterparts on the remote partition. )
 *
 *
 *  A - Messages that have been allocated, but have not yet been sent to the
 *      remote partition.
 *
 *  B - Messages that have been sent, but have not yet been acknowledged by the
 *      remote partition as having been received.
 *
 *  C - Area that needs to be prepared for the copying of sent messages, by
 *      the clearing of the message flags of any previously received messages.
 *
 *  D - Area into which sent messages are to be copied from the remote
 *      partition's local_msgqueue and then delivered to their intended
 *      recipients. [ To allow for a multi-message copy, another pointer
 *      (next_msg_to_pull) has been added to keep track of the next message
 *      number needing to be copied (pulled). It chases after w_remote_GP.put.
 *      Any messages lying between w_local_GP.get and next_msg_to_pull have
 *      been copied and are ready to be delivered. ]
 *
 *  E - Messages that have been copied and delivered, but have not yet been
 *      acknowledged by the recipient as having been received.
 *
 *  F - Messages that have been acknowledged, but XPC has not yet notified the
 *      sender that the message was received by its intended recipient.
 *      This is also an area that needs to be prepared for the allocating of
 *      new messages, by the clearing of the message flags of the acknowledged
 *      messages.
 */
struct xpc_channel {
        short partid;           /* ID of remote partition connected */
        spinlock_t lock;        /* lock for updating this structure */
        u32 flags;              /* general flags */

        enum xp_retval reason;  /* reason why channel is disconnect'g */
        int reason_line;        /* line# disconnect initiated from */

        u16 number;             /* channel # */

        u16 msg_size;           /* sizeof each msg entry */
        u16 local_nentries;     /* #of msg entries in local msg queue */
        u16 remote_nentries;    /* #of msg entries in remote msg queue */

        void *local_msgqueue_base;      /* base address of kmalloc'd space */
        struct xpc_msg *local_msgqueue; /* local message queue */
        void *remote_msgqueue_base;     /* base address of kmalloc'd space */
        struct xpc_msg *remote_msgqueue; /* cached copy of remote partition's */
                                         /* local message queue */
        u64 remote_msgqueue_pa; /* phys addr of remote partition's */
                                /* local message queue */

        atomic_t references;    /* #of external references to queues */

        atomic_t n_on_msg_allocate_wq;  /* #on msg allocation wait queue */
        wait_queue_head_t msg_allocate_wq;      /* msg allocation wait queue */

        u8 delayed_IPI_flags;   /* IPI flags received, but delayed */
                                /* action until channel disconnected */

        /* queue of msg senders who want to be notified when msg received */

        atomic_t n_to_notify;   /* #of msg senders to notify */
        struct xpc_notify *notify_queue;    /* notify queue for messages sent */

        xpc_channel_func func;  /* user's channel function */
        void *key;              /* pointer to user's key */

        struct mutex msg_to_pull_mutex; /* next msg to pull serialization */
        struct completion wdisconnect_wait;    /* wait for channel disconnect */

        struct xpc_openclose_args *local_openclose_args; /* args passed on */
                                             /* opening or closing of channel */

        /* various flavors of local and remote Get/Put values */

        struct xpc_gp *local_GP;        /* local Get/Put values */
        struct xpc_gp remote_GP;        /* remote Get/Put values */
        struct xpc_gp w_local_GP;       /* working local Get/Put values */
        struct xpc_gp w_remote_GP;      /* working remote Get/Put values */
        s64 next_msg_to_pull;   /* Put value of next msg to pull */

        /* kthread management related fields */

        atomic_t kthreads_assigned;     /* #of kthreads assigned to channel */
        u32 kthreads_assigned_limit;    /* limit on #of kthreads assigned */
        atomic_t kthreads_idle; /* #of kthreads idle waiting for work */
        u32 kthreads_idle_limit;        /* limit on #of kthreads idle */
        atomic_t kthreads_active;       /* #of kthreads actively working */

        wait_queue_head_t idle_wq;      /* idle kthread wait queue */

} ____cacheline_aligned;

/* struct xpc_channel flags */

#define XPC_C_WASCONNECTED      0x00000001      /* channel was connected */

#define XPC_C_ROPENREPLY        0x00000002      /* remote open channel reply */
#define XPC_C_OPENREPLY         0x00000004      /* local open channel reply */
#define XPC_C_ROPENREQUEST      0x00000008     /* remote open channel request */
#define XPC_C_OPENREQUEST       0x00000010      /* local open channel request */

#define XPC_C_SETUP             0x00000020 /* channel's msgqueues are alloc'd */
#define XPC_C_CONNECTEDCALLOUT  0x00000040     /* connected callout initiated */
#define XPC_C_CONNECTEDCALLOUT_MADE \
                                0x00000080     /* connected callout completed */
#define XPC_C_CONNECTED         0x00000100      /* local channel is connected */
#define XPC_C_CONNECTING        0x00000200      /* channel is being connected */

#define XPC_C_RCLOSEREPLY       0x00000400      /* remote close channel reply */
#define XPC_C_CLOSEREPLY        0x00000800      /* local close channel reply */
#define XPC_C_RCLOSEREQUEST     0x00001000    /* remote close channel request */
#define XPC_C_CLOSEREQUEST      0x00002000     /* local close channel request */

#define XPC_C_DISCONNECTED      0x00004000      /* channel is disconnected */
#define XPC_C_DISCONNECTING     0x00008000   /* channel is being disconnected */
#define XPC_C_DISCONNECTINGCALLOUT \
                                0x00010000 /* disconnecting callout initiated */
#define XPC_C_DISCONNECTINGCALLOUT_MADE \
                                0x00020000 /* disconnecting callout completed */
#define XPC_C_WDISCONNECT       0x00040000  /* waiting for channel disconnect */

/*
 * Manages channels on a partition basis. There is one of these structures
 * for each partition (a partition will never utilize the structure that
 * represents itself).
 */
struct xpc_partition {

        /* XPC HB infrastructure */

        u8 remote_rp_version;   /* version# of partition's rsvd pg */
        struct timespec remote_rp_stamp; /* time when rsvd pg was initialized */
        u64 remote_rp_pa;       /* phys addr of partition's rsvd pg */
        u64 remote_vars_pa;     /* phys addr of partition's vars */
        u64 remote_vars_part_pa;        /* phys addr of partition's vars part */
        u64 last_heartbeat;     /* HB at last read */
        u64 remote_amos_page_pa;        /* phys addr of partition's amos page */
        int remote_act_nasid;   /* active part's act/deact nasid */
        int remote_act_phys_cpuid;      /* active part's act/deact phys cpuid */
        u32 act_IRQ_rcvd;       /* IRQs since activation */
        spinlock_t act_lock;    /* protect updating of act_state */
        u8 act_state;           /* from XPC HB viewpoint */
        u8 remote_vars_version; /* version# of partition's vars */
        enum xp_retval reason;  /* reason partition is deactivating */
        int reason_line;        /* line# deactivation initiated from */
        int reactivate_nasid;   /* nasid in partition to reactivate */

        unsigned long disengage_request_timeout;        /* timeout in jiffies */
        struct timer_list disengage_request_timer;

        /* XPC infrastructure referencing and teardown control */

        u8 setup_state;         /* infrastructure setup state */
        wait_queue_head_t teardown_wq;  /* kthread waiting to teardown infra */
        atomic_t references;    /* #of references to infrastructure */

        /*
         * NONE OF THE PRECEDING FIELDS OF THIS STRUCTURE WILL BE CLEARED WHEN
         * XPC SETS UP THE NECESSARY INFRASTRUCTURE TO SUPPORT CROSS PARTITION
         * COMMUNICATION. ALL OF THE FOLLOWING FIELDS WILL BE CLEARED. (THE
         * 'nchannels' FIELD MUST BE THE FIRST OF THE FIELDS TO BE CLEARED.)
         */

        u8 nchannels;           /* #of defined channels supported */
        atomic_t nchannels_active;  /* #of channels that are not DISCONNECTED */
        atomic_t nchannels_engaged;  /* #of channels engaged with remote part */
        struct xpc_channel *channels;   /* array of channel structures */

        void *local_GPs_base;   /* base address of kmalloc'd space */
        struct xpc_gp *local_GPs;       /* local Get/Put values */
        void *remote_GPs_base;  /* base address of kmalloc'd space */
        struct xpc_gp *remote_GPs;      /* copy of remote partition's local */
                                        /* Get/Put values */
        u64 remote_GPs_pa;      /* phys address of remote partition's local */
                                /* Get/Put values */

        /* fields used to pass args when opening or closing a channel */

        void *local_openclose_args_base;   /* base address of kmalloc'd space */
        struct xpc_openclose_args *local_openclose_args;      /* local's args */
        void *remote_openclose_args_base;  /* base address of kmalloc'd space */
        struct xpc_openclose_args *remote_openclose_args; /* copy of remote's */
                                                          /* args */
        u64 remote_openclose_args_pa;   /* phys addr of remote's args */

        /* IPI sending, receiving and handling related fields */

        int remote_IPI_nasid;   /* nasid of where to send IPIs */
        int remote_IPI_phys_cpuid;      /* phys CPU ID of where to send IPIs */
        AMO_t *remote_IPI_amo_va;    /* address of remote IPI AMO_t structure */

        AMO_t *local_IPI_amo_va;        /* address of IPI AMO_t structure */
        u64 local_IPI_amo;      /* IPI amo flags yet to be handled */
        char IPI_owner[8];      /* IPI owner's name */
        struct timer_list dropped_IPI_timer;    /* dropped IPI timer */

        spinlock_t IPI_lock;    /* IPI handler lock */

        /* channel manager related fields */

        atomic_t channel_mgr_requests;  /* #of requests to activate chan mgr */
        wait_queue_head_t channel_mgr_wq;       /* channel mgr's wait queue */

} ____cacheline_aligned;

/* struct xpc_partition act_state values (for XPC HB) */

#define XPC_P_INACTIVE          0x00    /* partition is not active */
#define XPC_P_ACTIVATION_REQ    0x01    /* created thread to activate */
#define XPC_P_ACTIVATING        0x02    /* activation thread started */
#define XPC_P_ACTIVE            0x03    /* xpc_partition_up() was called */
#define XPC_P_DEACTIVATING      0x04    /* partition deactivation initiated */

#define XPC_DEACTIVATE_PARTITION(_p, _reason) \
                        xpc_deactivate_partition(__LINE__, (_p), (_reason))

/* struct xpc_partition setup_state values */

#define XPC_P_UNSET             0x00    /* infrastructure was never setup */
#define XPC_P_SETUP             0x01    /* infrastructure is setup */
#define XPC_P_WTEARDOWN         0x02    /* waiting to teardown infrastructure */
#define XPC_P_TORNDOWN          0x03    /* infrastructure is torndown */

/*
 * struct xpc_partition IPI_timer #of seconds to wait before checking for
 * dropped IPIs. These occur whenever an IPI amo write doesn't complete until
 * after the IPI was received.
 */
#define XPC_P_DROPPED_IPI_WAIT  (0.25 * HZ)

/* number of seconds to wait for other partitions to disengage */
#define XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT 90

/* interval in seconds to print 'waiting disengagement' messages */
#define XPC_DISENGAGE_PRINTMSG_INTERVAL         10

#define XPC_PARTID(_p)  ((short)((_p) - &xpc_partitions[0]))

/* found in xp_main.c */
extern struct xpc_registration xpc_registrations[];

/* found in xpc_main.c */
extern struct device *xpc_part;
extern struct device *xpc_chan;
extern int xpc_disengage_request_timelimit;
extern int xpc_disengage_request_timedout;
extern irqreturn_t xpc_notify_IRQ_handler(int, void *);
extern void xpc_dropped_IPI_check(struct xpc_partition *);
extern void xpc_activate_partition(struct xpc_partition *);
extern void xpc_activate_kthreads(struct xpc_channel *, int);
extern void xpc_create_kthreads(struct xpc_channel *, int, int);
extern void xpc_disconnect_wait(int);

/* found in xpc_partition.c */
extern int xpc_exiting;
extern struct xpc_vars *xpc_vars;
extern struct xpc_rsvd_page *xpc_rsvd_page;
extern struct xpc_vars_part *xpc_vars_part;
extern struct xpc_partition *xpc_partitions;
extern char *xpc_remote_copy_buffer;
extern void *xpc_remote_copy_buffer_base;
extern void *xpc_kmalloc_cacheline_aligned(size_t, gfp_t, void **);
extern struct xpc_rsvd_page *xpc_rsvd_page_init(void);
extern void xpc_allow_IPI_ops(void);
extern void xpc_restrict_IPI_ops(void);
extern int xpc_identify_act_IRQ_sender(void);
extern int xpc_partition_disengaged(struct xpc_partition *);
extern enum xp_retval xpc_mark_partition_active(struct xpc_partition *);
extern void xpc_mark_partition_inactive(struct xpc_partition *);
extern void xpc_discovery(void);
extern void xpc_check_remote_hb(void);
extern void xpc_deactivate_partition(const int, struct xpc_partition *,
                                     enum xp_retval);
extern enum xp_retval xpc_initiate_partid_to_nasids(short, void *);

/* found in xpc_channel.c */
extern void xpc_initiate_connect(int);
extern void xpc_initiate_disconnect(int);
extern enum xp_retval xpc_initiate_allocate(short, int, u32, void **);
extern enum xp_retval xpc_initiate_send(short, int, void *);
extern enum xp_retval xpc_initiate_send_notify(short, int, void *,
                                               xpc_notify_func, void *);
extern void xpc_initiate_received(short, int, void *);
extern enum xp_retval xpc_setup_infrastructure(struct xpc_partition *);
extern enum xp_retval xpc_pull_remote_vars_part(struct xpc_partition *);
extern void xpc_process_channel_activity(struct xpc_partition *);
extern void xpc_connected_callout(struct xpc_channel *);
extern void xpc_deliver_msg(struct xpc_channel *);
extern void xpc_disconnect_channel(const int, struct xpc_channel *,
                                   enum xp_retval, unsigned long *);
extern void xpc_disconnect_callout(struct xpc_channel *, enum xp_retval);
extern void xpc_partition_going_down(struct xpc_partition *, enum xp_retval);
extern void xpc_teardown_infrastructure(struct xpc_partition *);

static inline void
xpc_wakeup_channel_mgr(struct xpc_partition *part)
{
        if (atomic_inc_return(&part->channel_mgr_requests) == 1)
                wake_up(&part->channel_mgr_wq);
}

/*
 * These next two inlines are used to keep us from tearing down a channel's
 * msg queues while a thread may be referencing them.
 */
static inline void
xpc_msgqueue_ref(struct xpc_channel *ch)
{
        atomic_inc(&ch->references);
}

static inline void
xpc_msgqueue_deref(struct xpc_channel *ch)
{
        s32 refs = atomic_dec_return(&ch->references);

        DBUG_ON(refs < 0);
        if (refs == 0)
                xpc_wakeup_channel_mgr(&xpc_partitions[ch->partid]);
}

#define XPC_DISCONNECT_CHANNEL(_ch, _reason, _irqflgs) \
                xpc_disconnect_channel(__LINE__, _ch, _reason, _irqflgs)

/*
 * These two inlines are used to keep us from tearing down a partition's
 * setup infrastructure while a thread may be referencing it.
 */
static inline void
xpc_part_deref(struct xpc_partition *part)
{
        s32 refs = atomic_dec_return(&part->references);

        DBUG_ON(refs < 0);
        if (refs == 0 && part->setup_state == XPC_P_WTEARDOWN)
                wake_up(&part->teardown_wq);
}

static inline int
xpc_part_ref(struct xpc_partition *part)
{
        int setup;

        atomic_inc(&part->references);
        setup = (part->setup_state == XPC_P_SETUP);
        if (!setup)
                xpc_part_deref(part);

        return setup;
}

/*
 * The following macro is to be used for the setting of the reason and
 * reason_line fields in both the struct xpc_channel and struct xpc_partition
 * structures.
 */
#define XPC_SET_REASON(_p, _reason, _line) \
        { \
                (_p)->reason = _reason; \
                (_p)->reason_line = _line; \
        }

/*
 * This next set of inlines are used to keep track of when a partition is
 * potentially engaged in accessing memory belonging to another partition.
 */

static inline void
xpc_mark_partition_engaged(struct xpc_partition *part)
{
        unsigned long irq_flags;
        AMO_t *amo = (AMO_t *)__va(part->remote_amos_page_pa +
                                   (XPC_ENGAGED_PARTITIONS_AMO *
                                    sizeof(AMO_t)));

        local_irq_save(irq_flags);

        /* set bit corresponding to our partid in remote partition's AMO */
        FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_OR,
                         (1UL << sn_partition_id));
        /*
         * We must always use the nofault function regardless of whether we
         * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
         * didn't, we'd never know that the other partition is down and would
         * keep sending IPIs and AMOs to it until the heartbeat times out.
         */
        (void)xp_nofault_PIOR((u64 *)GLOBAL_MMR_ADDR(NASID_GET(&amo->
                                                               variable),
                                                     xp_nofault_PIOR_target));

        local_irq_restore(irq_flags);
}

static inline void
xpc_mark_partition_disengaged(struct xpc_partition *part)
{
        unsigned long irq_flags;
        AMO_t *amo = (AMO_t *)__va(part->remote_amos_page_pa +
                                   (XPC_ENGAGED_PARTITIONS_AMO *
                                    sizeof(AMO_t)));

        local_irq_save(irq_flags);

        /* clear bit corresponding to our partid in remote partition's AMO */
        FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_AND,
                         ~(1UL << sn_partition_id));
        /*
         * We must always use the nofault function regardless of whether we
         * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
         * didn't, we'd never know that the other partition is down and would
         * keep sending IPIs and AMOs to it until the heartbeat times out.
         */
        (void)xp_nofault_PIOR((u64 *)GLOBAL_MMR_ADDR(NASID_GET(&amo->
                                                               variable),
                                                     xp_nofault_PIOR_target));

        local_irq_restore(irq_flags);
}

static inline void
xpc_request_partition_disengage(struct xpc_partition *part)
{
        unsigned long irq_flags;
        AMO_t *amo = (AMO_t *)__va(part->remote_amos_page_pa +
                                   (XPC_DISENGAGE_REQUEST_AMO * sizeof(AMO_t)));

        local_irq_save(irq_flags);

        /* set bit corresponding to our partid in remote partition's AMO */
        FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_OR,
                         (1UL << sn_partition_id));
        /*
         * We must always use the nofault function regardless of whether we
         * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
         * didn't, we'd never know that the other partition is down and would
         * keep sending IPIs and AMOs to it until the heartbeat times out.
         */
        (void)xp_nofault_PIOR((u64 *)GLOBAL_MMR_ADDR(NASID_GET(&amo->
                                                               variable),
                                                     xp_nofault_PIOR_target));

        local_irq_restore(irq_flags);
}

static inline void
xpc_cancel_partition_disengage_request(struct xpc_partition *part)
{
        unsigned long irq_flags;
        AMO_t *amo = (AMO_t *)__va(part->remote_amos_page_pa +
                                   (XPC_DISENGAGE_REQUEST_AMO * sizeof(AMO_t)));

        local_irq_save(irq_flags);

        /* clear bit corresponding to our partid in remote partition's AMO */
        FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_AND,
                         ~(1UL << sn_partition_id));
        /*
         * We must always use the nofault function regardless of whether we
         * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
         * didn't, we'd never know that the other partition is down and would
         * keep sending IPIs and AMOs to it until the heartbeat times out.
         */
        (void)xp_nofault_PIOR((u64 *)GLOBAL_MMR_ADDR(NASID_GET(&amo->
                                                               variable),
                                                     xp_nofault_PIOR_target));

        local_irq_restore(irq_flags);
}

static inline u64
xpc_partition_engaged(u64 partid_mask)
{
        AMO_t *amo = xpc_vars->amos_page + XPC_ENGAGED_PARTITIONS_AMO;

        /* return our partition's AMO variable ANDed with partid_mask */
        return (FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_LOAD) &
                partid_mask);
}

static inline u64
xpc_partition_disengage_requested(u64 partid_mask)
{
        AMO_t *amo = xpc_vars->amos_page + XPC_DISENGAGE_REQUEST_AMO;

        /* return our partition's AMO variable ANDed with partid_mask */
        return (FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_LOAD) &
                partid_mask);
}

static inline void
xpc_clear_partition_engaged(u64 partid_mask)
{
        AMO_t *amo = xpc_vars->amos_page + XPC_ENGAGED_PARTITIONS_AMO;

        /* clear bit(s) based on partid_mask in our partition's AMO */
        FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_AND,
                         ~partid_mask);
}

static inline void
xpc_clear_partition_disengage_request(u64 partid_mask)
{
        AMO_t *amo = xpc_vars->amos_page + XPC_DISENGAGE_REQUEST_AMO;

        /* clear bit(s) based on partid_mask in our partition's AMO */
        FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_AND,
                         ~partid_mask);
}

/*
 * The following set of macros and inlines are used for the sending and
 * receiving of IPIs (also known as IRQs). There are two flavors of IPIs,
 * one that is associated with partition activity (SGI_XPC_ACTIVATE) and
 * the other that is associated with channel activity (SGI_XPC_NOTIFY).
 */

static inline u64
xpc_IPI_receive(AMO_t *amo)
{
        return FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_CLEAR);
}

static inline enum xp_retval
xpc_IPI_send(AMO_t *amo, u64 flag, int nasid, int phys_cpuid, int vector)
{
        int ret = 0;
        unsigned long irq_flags;

        local_irq_save(irq_flags);

        FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_OR, flag);
        sn_send_IPI_phys(nasid, phys_cpuid, vector, 0);

        /*
         * We must always use the nofault function regardless of whether we
         * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
         * didn't, we'd never know that the other partition is down and would
         * keep sending IPIs and AMOs to it until the heartbeat times out.
         */
        ret = xp_nofault_PIOR((u64 *)GLOBAL_MMR_ADDR(NASID_GET(&amo->variable),
                                                     xp_nofault_PIOR_target));

        local_irq_restore(irq_flags);

        return ((ret == 0) ? xpSuccess : xpPioReadError);
}

/*
 * IPIs associated with SGI_XPC_ACTIVATE IRQ.
 */

/*
 * Flag the appropriate AMO variable and send an IPI to the specified node.
 */
static inline void
xpc_activate_IRQ_send(u64 amos_page_pa, int from_nasid, int to_nasid,
                      int to_phys_cpuid)
{
        int w_index = XPC_NASID_W_INDEX(from_nasid);
        int b_index = XPC_NASID_B_INDEX(from_nasid);
        AMO_t *amos = (AMO_t *)__va(amos_page_pa +
                                    (XPC_ACTIVATE_IRQ_AMOS * sizeof(AMO_t)));

        (void)xpc_IPI_send(&amos[w_index], (1UL << b_index), to_nasid,
                           to_phys_cpuid, SGI_XPC_ACTIVATE);
}

static inline void
xpc_IPI_send_activate(struct xpc_vars *vars)
{
        xpc_activate_IRQ_send(vars->amos_page_pa, cnodeid_to_nasid(0),
                              vars->act_nasid, vars->act_phys_cpuid);
}

static inline void
xpc_IPI_send_activated(struct xpc_partition *part)
{
        xpc_activate_IRQ_send(part->remote_amos_page_pa, cnodeid_to_nasid(0),
                              part->remote_act_nasid,
                              part->remote_act_phys_cpuid);
}

static inline void
xpc_IPI_send_reactivate(struct xpc_partition *part)
{
        xpc_activate_IRQ_send(xpc_vars->amos_page_pa, part->reactivate_nasid,
                              xpc_vars->act_nasid, xpc_vars->act_phys_cpuid);
}

static inline void
xpc_IPI_send_disengage(struct xpc_partition *part)
{
        xpc_activate_IRQ_send(part->remote_amos_page_pa, cnodeid_to_nasid(0),
                              part->remote_act_nasid,
                              part->remote_act_phys_cpuid);
}

/*
 * IPIs associated with SGI_XPC_NOTIFY IRQ.
 */

/*
 * Send an IPI to the remote partition that is associated with the
 * specified channel.
 */
#define XPC_NOTIFY_IRQ_SEND(_ch, _ipi_f, _irq_f) \
                xpc_notify_IRQ_send(_ch, _ipi_f, #_ipi_f, _irq_f)

static inline void
xpc_notify_IRQ_send(struct xpc_channel *ch, u8 ipi_flag, char *ipi_flag_string,
                    unsigned long *irq_flags)
{
        struct xpc_partition *part = &xpc_partitions[ch->partid];
        enum xp_retval ret;

        if (likely(part->act_state != XPC_P_DEACTIVATING)) {
                ret = xpc_IPI_send(part->remote_IPI_amo_va,
                                   (u64)ipi_flag << (ch->number * 8),
                                   part->remote_IPI_nasid,
                                   part->remote_IPI_phys_cpuid, SGI_XPC_NOTIFY);
                dev_dbg(xpc_chan, "%s sent to partid=%d, channel=%d, ret=%d\n",
                        ipi_flag_string, ch->partid, ch->number, ret);
                if (unlikely(ret != xpSuccess)) {
                        if (irq_flags != NULL)
                                spin_unlock_irqrestore(&ch->lock, *irq_flags);
                        XPC_DEACTIVATE_PARTITION(part, ret);
                        if (irq_flags != NULL)
                                spin_lock_irqsave(&ch->lock, *irq_flags);
                }
        }
}

/*
 * Make it look like the remote partition, which is associated with the
 * specified channel, sent us an IPI. This faked IPI will be handled
 * by xpc_dropped_IPI_check().
 */
#define XPC_NOTIFY_IRQ_SEND_LOCAL(_ch, _ipi_f) \
                xpc_notify_IRQ_send_local(_ch, _ipi_f, #_ipi_f)

static inline void
xpc_notify_IRQ_send_local(struct xpc_channel *ch, u8 ipi_flag,
                          char *ipi_flag_string)
{
        struct xpc_partition *part = &xpc_partitions[ch->partid];

        FETCHOP_STORE_OP(TO_AMO((u64)&part->local_IPI_amo_va->variable),
                         FETCHOP_OR, ((u64)ipi_flag << (ch->number * 8)));
        dev_dbg(xpc_chan, "%s sent local from partid=%d, channel=%d\n",
                ipi_flag_string, ch->partid, ch->number);
}

/*
 * The sending and receiving of IPIs includes the setting of an AMO variable
 * to indicate the reason the IPI was sent. The 64-bit variable is divided
 * up into eight bytes, ordered from right to left. Byte zero pertains to
 * channel 0, byte one to channel 1, and so on. Each byte is described by
 * the following IPI flags.
 */

#define XPC_IPI_CLOSEREQUEST    0x01
#define XPC_IPI_CLOSEREPLY      0x02
#define XPC_IPI_OPENREQUEST     0x04
#define XPC_IPI_OPENREPLY       0x08
#define XPC_IPI_MSGREQUEST      0x10

/* given an AMO variable and a channel#, get its associated IPI flags */
#define XPC_GET_IPI_FLAGS(_amo, _c)     ((u8) (((_amo) >> ((_c) * 8)) & 0xff))
#define XPC_SET_IPI_FLAGS(_amo, _c, _f) (_amo) |= ((u64) (_f) << ((_c) * 8))

#define XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(_amo) ((_amo) & 0x0f0f0f0f0f0f0f0fUL)
#define XPC_ANY_MSG_IPI_FLAGS_SET(_amo)       ((_amo) & 0x1010101010101010UL)

static inline void
xpc_IPI_send_closerequest(struct xpc_channel *ch, unsigned long *irq_flags)
{
        struct xpc_openclose_args *args = ch->local_openclose_args;

        args->reason = ch->reason;

        XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_CLOSEREQUEST, irq_flags);
}

static inline void
xpc_IPI_send_closereply(struct xpc_channel *ch, unsigned long *irq_flags)
{
        XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_CLOSEREPLY, irq_flags);
}

static inline void
xpc_IPI_send_openrequest(struct xpc_channel *ch, unsigned long *irq_flags)
{
        struct xpc_openclose_args *args = ch->local_openclose_args;

        args->msg_size = ch->msg_size;
        args->local_nentries = ch->local_nentries;

        XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_OPENREQUEST, irq_flags);
}

static inline void
xpc_IPI_send_openreply(struct xpc_channel *ch, unsigned long *irq_flags)
{
        struct xpc_openclose_args *args = ch->local_openclose_args;

        args->remote_nentries = ch->remote_nentries;
        args->local_nentries = ch->local_nentries;
        args->local_msgqueue_pa = __pa(ch->local_msgqueue);

        XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_OPENREPLY, irq_flags);
}

static inline void
xpc_IPI_send_msgrequest(struct xpc_channel *ch)
{
        XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_MSGREQUEST, NULL);
}

static inline void
xpc_IPI_send_local_msgrequest(struct xpc_channel *ch)
{
        XPC_NOTIFY_IRQ_SEND_LOCAL(ch, XPC_IPI_MSGREQUEST);
}

/*
>>> this block comment needs to be moved and re-written.
 * Memory for XPC's AMO variables is allocated by the MSPEC driver. These
 * pages are located in the lowest granule. The lowest granule uses 4k pages
 * for cached references and an alternate TLB handler to never provide a
 * cacheable mapping for the entire region. This will prevent speculative
 * reading of cached copies of our lines from being issued which will cause
 * a PI FSB Protocol error to be generated by the SHUB. For XPC, we need 64
 * AMO variables (based on xp_max_npartitions) for message notification and an
 * additional 128 AMO variables (based on XP_NASID_MASK_WORDS) for partition
 * activation and 2 AMO variables for partition deactivation.
 */
static inline AMO_t *
xpc_IPI_init(int index)
{
        AMO_t *amo = xpc_vars->amos_page + index;

        (void)xpc_IPI_receive(amo);     /* clear AMO variable */
        return amo;
}

static inline enum xp_retval
xpc_map_bte_errors(bte_result_t error)
{
        return ((error == BTE_SUCCESS) ? xpSuccess : xpBteCopyError);
}

/*
 * Check to see if there is any channel activity to/from the specified
 * partition.
 */
static inline void
xpc_check_for_channel_activity(struct xpc_partition *part)
{
        u64 IPI_amo;
        unsigned long irq_flags;

        IPI_amo = xpc_IPI_receive(part->local_IPI_amo_va);
        if (IPI_amo == 0)
                return;

        spin_lock_irqsave(&part->IPI_lock, irq_flags);
        part->local_IPI_amo |= IPI_amo;
        spin_unlock_irqrestore(&part->IPI_lock, irq_flags);

        dev_dbg(xpc_chan, "received IPI from partid=%d, IPI_amo=0x%lx\n",
                XPC_PARTID(part), IPI_amo);

        xpc_wakeup_channel_mgr(part);
}

#endif /* _DRIVERS_MISC_SGIXP_XPC_H */