/*
 * 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.
 */

/*
 * Cross Partition (XP) base.
 *
 *      XP provides a base from which its users can interact
 *      with XPC, yet not be dependent on XPC.
 *
 */

#include <linux/module.h>
#include <linux/device.h>
#include "xp.h"

/* define the XP debug device structures to be used with dev_dbg() et al */

static struct device_driver xp_dbg_name = {
        .name = "xp"
};

static struct device xp_dbg_subname = {
        .init_name = "",                /* set to "" */
        .driver = &xp_dbg_name
};

struct device *xp = &xp_dbg_subname;

/* max #of partitions possible */
short xp_max_npartitions;
EXPORT_SYMBOL_GPL(xp_max_npartitions);

short xp_partition_id;
EXPORT_SYMBOL_GPL(xp_partition_id);

u8 xp_region_size;
EXPORT_SYMBOL_GPL(xp_region_size);

unsigned long (*xp_pa) (void *addr);
EXPORT_SYMBOL_GPL(xp_pa);

unsigned long (*xp_socket_pa) (unsigned long gpa);
EXPORT_SYMBOL_GPL(xp_socket_pa);

enum xp_retval (*xp_remote_memcpy) (unsigned long dst_gpa,
                                    const unsigned long src_gpa, size_t len);
EXPORT_SYMBOL_GPL(xp_remote_memcpy);

int (*xp_cpu_to_nasid) (int cpuid);
EXPORT_SYMBOL_GPL(xp_cpu_to_nasid);

enum xp_retval (*xp_expand_memprotect) (unsigned long phys_addr,
                                        unsigned long size);
EXPORT_SYMBOL_GPL(xp_expand_memprotect);
enum xp_retval (*xp_restrict_memprotect) (unsigned long phys_addr,
                                          unsigned long size);
EXPORT_SYMBOL_GPL(xp_restrict_memprotect);

/*
 * xpc_registrations[] keeps track of xpc_connect()'s done by the kernel-level
 * users of XPC.
 */
struct xpc_registration xpc_registrations[XPC_MAX_NCHANNELS];
EXPORT_SYMBOL_GPL(xpc_registrations);

/*
 * Initialize the XPC interface to NULL to indicate that XPC isn't loaded.
 */
struct xpc_interface xpc_interface = { };
EXPORT_SYMBOL_GPL(xpc_interface);

/*
 * XPC calls this when it (the XPC module) has been loaded.
 */
void
xpc_set_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 *))
{
        xpc_interface.connect = connect;
        xpc_interface.disconnect = disconnect;
        xpc_interface.send = send;
        xpc_interface.send_notify = send_notify;
        xpc_interface.received = received;
        xpc_interface.partid_to_nasids = partid_to_nasids;
}
EXPORT_SYMBOL_GPL(xpc_set_interface);

/*
 * XPC calls this when it (the XPC module) is being unloaded.
 */
void
xpc_clear_interface(void)
{
        memset(&xpc_interface, 0, sizeof(xpc_interface));
}
EXPORT_SYMBOL_GPL(xpc_clear_interface);

/*
 * Register for automatic establishment of a channel connection whenever
 * a partition comes up.
 *
 * Arguments:
 *
 *      ch_number - channel # to register for connection.
 *      func - function to call for asynchronous notification of channel
 *             state changes (i.e., connection, disconnection, error) and
 *             the arrival of incoming messages.
 *      key - pointer to optional user-defined value that gets passed back
 *            to the user on any callouts made to func.
 *      payload_size - size in bytes of the XPC message's payload area which
 *                     contains a user-defined message. The user should make
 *                     this large enough to hold their largest message.
 *      nentries - max #of XPC message entries a message queue can contain.
 *                 The actual number, which is determined when a connection
 *                 is established and may be less then requested, will be
 *                 passed to the user via the xpConnected callout.
 *      assigned_limit - max number of kthreads allowed to be processing
 *                       messages (per connection) at any given instant.
 *      idle_limit - max number of kthreads allowed to be idle at any given
 *                   instant.
 */
enum xp_retval
xpc_connect(int ch_number, xpc_channel_func func, void *key, u16 payload_size,
            u16 nentries, u32 assigned_limit, u32 idle_limit)
{
        struct xpc_registration *registration;

        DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);
        DBUG_ON(payload_size == 0 || nentries == 0);
        DBUG_ON(func == NULL);
        DBUG_ON(assigned_limit == 0 || idle_limit > assigned_limit);

        if (XPC_MSG_SIZE(payload_size) > XPC_MSG_MAX_SIZE)
                return xpPayloadTooBig;

        registration = &xpc_registrations[ch_number];

        if (mutex_lock_interruptible(&registration->mutex) != 0)
                return xpInterrupted;

        /* if XPC_CHANNEL_REGISTERED(ch_number) */
        if (registration->func != NULL) {
                mutex_unlock(&registration->mutex);
                return xpAlreadyRegistered;
        }

        /* register the channel for connection */
        registration->entry_size = XPC_MSG_SIZE(payload_size);
        registration->nentries = nentries;
        registration->assigned_limit = assigned_limit;
        registration->idle_limit = idle_limit;
        registration->key = key;
        registration->func = func;

        mutex_unlock(&registration->mutex);

        if (xpc_interface.connect)
                xpc_interface.connect(ch_number);

        return xpSuccess;
}
EXPORT_SYMBOL_GPL(xpc_connect);

/*
 * Remove the registration for automatic connection of the specified channel
 * when a partition comes up.
 *
 * Before returning this xpc_disconnect() will wait for all connections on the
 * specified channel have been closed/torndown. So the caller can be assured
 * that they will not be receiving any more callouts from XPC to their
 * function registered via xpc_connect().
 *
 * Arguments:
 *
 *      ch_number - channel # to unregister.
 */
void
xpc_disconnect(int ch_number)
{
        struct xpc_registration *registration;

        DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);

        registration = &xpc_registrations[ch_number];

        /*
         * We've decided not to make this a down_interruptible(), since we
         * figured XPC's users will just turn around and call xpc_disconnect()
         * again anyways, so we might as well wait, if need be.
         */
        mutex_lock(&registration->mutex);

        /* if !XPC_CHANNEL_REGISTERED(ch_number) */
        if (registration->func == NULL) {
                mutex_unlock(&registration->mutex);
                return;
        }

        /* remove the connection registration for the specified channel */
        registration->func = NULL;
        registration->key = NULL;
        registration->nentries = 0;
        registration->entry_size = 0;
        registration->assigned_limit = 0;
        registration->idle_limit = 0;

        if (xpc_interface.disconnect)
                xpc_interface.disconnect(ch_number);

        mutex_unlock(&registration->mutex);

        return;
}
EXPORT_SYMBOL_GPL(xpc_disconnect);

static int __init
xp_init(void)
{
        enum xp_retval ret;
        int ch_number;

        /* initialize the connection registration mutex */
        for (ch_number = 0; ch_number < XPC_MAX_NCHANNELS; ch_number++)
                mutex_init(&xpc_registrations[ch_number].mutex);

        if (is_uv_system())
                ret = xp_init_uv();
        else
                ret = 0;

        if (ret != xpSuccess)
                return ret;

        return 0;
}

module_init(xp_init);

static void __exit
xp_exit(void)
{
        if (is_uv_system())
                xp_exit_uv();
}

module_exit(xp_exit);

MODULE_AUTHOR("Silicon Graphics, Inc.");
MODULE_DESCRIPTION("Cross Partition (XP) base");
MODULE_LICENSE("GPL");