/*
 * Copyright (c) 2014 Mellanox Technologies. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef IB_UMEM_ODP_H
#define IB_UMEM_ODP_H

#include <rdma/ib_umem.h>
#include <rdma/ib_verbs.h>
#include <linux/interval_tree.h>

struct umem_odp_node {
        u64 __subtree_last;
        struct rb_node rb;
};

struct ib_umem_odp {
        /*
         * An array of the pages included in the on-demand paging umem.
         * Indices of pages that are currently not mapped into the device will
         * contain NULL.
         */
        struct page             **page_list;
        /*
         * An array of the same size as page_list, with DMA addresses mapped
         * for pages the pages in page_list. The lower two bits designate
         * access permissions. See ODP_READ_ALLOWED_BIT and
         * ODP_WRITE_ALLOWED_BIT.
         */
        dma_addr_t              *dma_list;
        /*
         * The umem_mutex protects the page_list and dma_list fields of an ODP
         * umem, allowing only a single thread to map/unmap pages. The mutex
         * also protects access to the mmu notifier counters.
         */
        struct mutex            umem_mutex;
        void                    *private; /* for the HW driver to use. */

        /* When false, use the notifier counter in the ucontext struct. */
        bool mn_counters_active;
        int notifiers_seq;
        int notifiers_count;

        /* A linked list of umems that don't have private mmu notifier
         * counters yet. */
        struct list_head no_private_counters;
        struct ib_umem          *umem;

        /* Tree tracking */
        struct umem_odp_node    interval_tree;

        struct completion       notifier_completion;
        int                     dying;
};

#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING

int ib_umem_odp_get(struct ib_ucontext *context, struct ib_umem *umem);

void ib_umem_odp_release(struct ib_umem *umem);

/*
 * The lower 2 bits of the DMA address signal the R/W permissions for
 * the entry. To upgrade the permissions, provide the appropriate
 * bitmask to the map_dma_pages function.
 *
 * Be aware that upgrading a mapped address might result in change of
 * the DMA address for the page.
 */
#define ODP_READ_ALLOWED_BIT  (1<<0ULL)
#define ODP_WRITE_ALLOWED_BIT (1<<1ULL)

#define ODP_DMA_ADDR_MASK (~(ODP_READ_ALLOWED_BIT | ODP_WRITE_ALLOWED_BIT))

int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 start_offset, u64 bcnt,
                              u64 access_mask, unsigned long current_seq);

void ib_umem_odp_unmap_dma_pages(struct ib_umem *umem, u64 start_offset,
                                 u64 bound);

void rbt_ib_umem_insert(struct umem_odp_node *node, struct rb_root *root);
void rbt_ib_umem_remove(struct umem_odp_node *node, struct rb_root *root);
typedef int (*umem_call_back)(struct ib_umem *item, u64 start, u64 end,
                              void *cookie);
/*
 * Call the callback on each ib_umem in the range. Returns the logical or of
 * the return values of the functions called.
 */
int rbt_ib_umem_for_each_in_range(struct rb_root *root, u64 start, u64 end,
                                  umem_call_back cb, void *cookie);

struct umem_odp_node *rbt_ib_umem_iter_first(struct rb_root *root,
                                             u64 start, u64 last);
struct umem_odp_node *rbt_ib_umem_iter_next(struct umem_odp_node *node,
                                            u64 start, u64 last);

static inline int ib_umem_mmu_notifier_retry(struct ib_umem *item,
                                             unsigned long mmu_seq)
{
        /*
         * This code is strongly based on the KVM code from
         * mmu_notifier_retry. Should be called with
         * the relevant locks taken (item->odp_data->umem_mutex
         * and the ucontext umem_mutex semaphore locked for read).
         */

        /* Do not allow page faults while the new ib_umem hasn't seen a state
         * with zero notifiers yet, and doesn't have its own valid set of
         * private counters. */
        if (!item->odp_data->mn_counters_active)
                return 1;

        if (unlikely(item->odp_data->notifiers_count))
                return 1;
        if (item->odp_data->notifiers_seq != mmu_seq)
                return 1;
        return 0;
}

#else /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */

static inline int ib_umem_odp_get(struct ib_ucontext *context,
                                  struct ib_umem *umem)
{
        return -EINVAL;
}

static inline void ib_umem_odp_release(struct ib_umem *umem) {}

#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */

#endif /* IB_UMEM_ODP_H */