/*
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 *   redistributing this file, you may do so under either license.
 *
 *   GPL LICENSE SUMMARY
 *
 *   Copyright (C) 2015 EMC Corporation. All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of version 2 of the GNU General Public License as
 *   published by the Free Software Foundation.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *   General Public License for more details.
 *
 *   BSD LICENSE
 *
 *   Copyright (C) 2015 EMC Corporation. All Rights Reserved.
 *
 *   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 copy
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * PCIe NTB Linux driver
 *
 * Contact Information:
 * Allen Hubbe <Allen.Hubbe@emc.com>
 */

#ifndef _NTB_H_
#define _NTB_H_

#include <linux/completion.h>
#include <linux/device.h>

struct ntb_client;
struct ntb_dev;
struct pci_dev;

/**
 * enum ntb_topo - NTB connection topology
 * @NTB_TOPO_NONE:      Topology is unknown or invalid.
 * @NTB_TOPO_PRI:       On primary side of local ntb.
 * @NTB_TOPO_SEC:       On secondary side of remote ntb.
 * @NTB_TOPO_B2B_USD:   On primary side of local ntb upstream of remote ntb.
 * @NTB_TOPO_B2B_DSD:   On primary side of local ntb downstream of remote ntb.
 */
enum ntb_topo {
        NTB_TOPO_NONE = -1,
        NTB_TOPO_PRI,
        NTB_TOPO_SEC,
        NTB_TOPO_B2B_USD,
        NTB_TOPO_B2B_DSD,
};

static inline int ntb_topo_is_b2b(enum ntb_topo topo)
{
        switch ((int)topo) {
        case NTB_TOPO_B2B_USD:
        case NTB_TOPO_B2B_DSD:
                return 1;
        }
        return 0;
}

static inline char *ntb_topo_string(enum ntb_topo topo)
{
        switch (topo) {
        case NTB_TOPO_NONE:     return "NTB_TOPO_NONE";
        case NTB_TOPO_PRI:      return "NTB_TOPO_PRI";
        case NTB_TOPO_SEC:      return "NTB_TOPO_SEC";
        case NTB_TOPO_B2B_USD:  return "NTB_TOPO_B2B_USD";
        case NTB_TOPO_B2B_DSD:  return "NTB_TOPO_B2B_DSD";
        }
        return "NTB_TOPO_INVALID";
}

/**
 * enum ntb_speed - NTB link training speed
 * @NTB_SPEED_AUTO:     Request the max supported speed.
 * @NTB_SPEED_NONE:     Link is not trained to any speed.
 * @NTB_SPEED_GEN1:     Link is trained to gen1 speed.
 * @NTB_SPEED_GEN2:     Link is trained to gen2 speed.
 * @NTB_SPEED_GEN3:     Link is trained to gen3 speed.
 */
enum ntb_speed {
        NTB_SPEED_AUTO = -1,
        NTB_SPEED_NONE = 0,
        NTB_SPEED_GEN1 = 1,
        NTB_SPEED_GEN2 = 2,
        NTB_SPEED_GEN3 = 3,
};

/**
 * enum ntb_width - NTB link training width
 * @NTB_WIDTH_AUTO:     Request the max supported width.
 * @NTB_WIDTH_NONE:     Link is not trained to any width.
 * @NTB_WIDTH_1:        Link is trained to 1 lane width.
 * @NTB_WIDTH_2:        Link is trained to 2 lane width.
 * @NTB_WIDTH_4:        Link is trained to 4 lane width.
 * @NTB_WIDTH_8:        Link is trained to 8 lane width.
 * @NTB_WIDTH_12:       Link is trained to 12 lane width.
 * @NTB_WIDTH_16:       Link is trained to 16 lane width.
 * @NTB_WIDTH_32:       Link is trained to 32 lane width.
 */
enum ntb_width {
        NTB_WIDTH_AUTO = -1,
        NTB_WIDTH_NONE = 0,
        NTB_WIDTH_1 = 1,
        NTB_WIDTH_2 = 2,
        NTB_WIDTH_4 = 4,
        NTB_WIDTH_8 = 8,
        NTB_WIDTH_12 = 12,
        NTB_WIDTH_16 = 16,
        NTB_WIDTH_32 = 32,
};

/**
 * struct ntb_client_ops - ntb client operations
 * @probe:              Notify client of a new device.
 * @remove:             Notify client to remove a device.
 */
struct ntb_client_ops {
        int (*probe)(struct ntb_client *client, struct ntb_dev *ntb);
        void (*remove)(struct ntb_client *client, struct ntb_dev *ntb);
};

static inline int ntb_client_ops_is_valid(const struct ntb_client_ops *ops)
{
        /* commented callbacks are not required: */
        return
                ops->probe                      &&
                ops->remove                     &&
                1;
}

/**
 * struct ntb_ctx_ops - ntb driver context operations
 * @link_event:         See ntb_link_event().
 * @db_event:           See ntb_db_event().
 */
struct ntb_ctx_ops {
        void (*link_event)(void *ctx);
        void (*db_event)(void *ctx, int db_vector);
};

static inline int ntb_ctx_ops_is_valid(const struct ntb_ctx_ops *ops)
{
        /* commented callbacks are not required: */
        return
                /* ops->link_event              && */
                /* ops->db_event                && */
                1;
}

/**
 * struct ntb_ctx_ops - ntb device operations
 * @mw_count:           See ntb_mw_count().
 * @mw_get_range:       See ntb_mw_get_range().
 * @mw_set_trans:       See ntb_mw_set_trans().
 * @mw_clear_trans:     See ntb_mw_clear_trans().
 * @link_is_up:         See ntb_link_is_up().
 * @link_enable:        See ntb_link_enable().
 * @link_disable:       See ntb_link_disable().
 * @db_is_unsafe:       See ntb_db_is_unsafe().
 * @db_valid_mask:      See ntb_db_valid_mask().
 * @db_vector_count:    See ntb_db_vector_count().
 * @db_vector_mask:     See ntb_db_vector_mask().
 * @db_read:            See ntb_db_read().
 * @db_set:             See ntb_db_set().
 * @db_clear:           See ntb_db_clear().
 * @db_read_mask:       See ntb_db_read_mask().
 * @db_set_mask:        See ntb_db_set_mask().
 * @db_clear_mask:      See ntb_db_clear_mask().
 * @peer_db_addr:       See ntb_peer_db_addr().
 * @peer_db_read:       See ntb_peer_db_read().
 * @peer_db_set:        See ntb_peer_db_set().
 * @peer_db_clear:      See ntb_peer_db_clear().
 * @peer_db_read_mask:  See ntb_peer_db_read_mask().
 * @peer_db_set_mask:   See ntb_peer_db_set_mask().
 * @peer_db_clear_mask: See ntb_peer_db_clear_mask().
 * @spad_is_unsafe:     See ntb_spad_is_unsafe().
 * @spad_count:         See ntb_spad_count().
 * @spad_read:          See ntb_spad_read().
 * @spad_write:         See ntb_spad_write().
 * @peer_spad_addr:     See ntb_peer_spad_addr().
 * @peer_spad_read:     See ntb_peer_spad_read().
 * @peer_spad_write:    See ntb_peer_spad_write().
 */
struct ntb_dev_ops {
        int (*mw_count)(struct ntb_dev *ntb);
        int (*mw_get_range)(struct ntb_dev *ntb, int idx,
                            phys_addr_t *base, resource_size_t *size,
                        resource_size_t *align, resource_size_t *align_size);
        int (*mw_set_trans)(struct ntb_dev *ntb, int idx,
                            dma_addr_t addr, resource_size_t size);
        int (*mw_clear_trans)(struct ntb_dev *ntb, int idx);

        int (*link_is_up)(struct ntb_dev *ntb,
                          enum ntb_speed *speed, enum ntb_width *width);
        int (*link_enable)(struct ntb_dev *ntb,
                           enum ntb_speed max_speed, enum ntb_width max_width);
        int (*link_disable)(struct ntb_dev *ntb);

        int (*db_is_unsafe)(struct ntb_dev *ntb);
        u64 (*db_valid_mask)(struct ntb_dev *ntb);
        int (*db_vector_count)(struct ntb_dev *ntb);
        u64 (*db_vector_mask)(struct ntb_dev *ntb, int db_vector);

        u64 (*db_read)(struct ntb_dev *ntb);
        int (*db_set)(struct ntb_dev *ntb, u64 db_bits);
        int (*db_clear)(struct ntb_dev *ntb, u64 db_bits);

        u64 (*db_read_mask)(struct ntb_dev *ntb);
        int (*db_set_mask)(struct ntb_dev *ntb, u64 db_bits);
        int (*db_clear_mask)(struct ntb_dev *ntb, u64 db_bits);

        int (*peer_db_addr)(struct ntb_dev *ntb,
                            phys_addr_t *db_addr, resource_size_t *db_size);
        u64 (*peer_db_read)(struct ntb_dev *ntb);
        int (*peer_db_set)(struct ntb_dev *ntb, u64 db_bits);
        int (*peer_db_clear)(struct ntb_dev *ntb, u64 db_bits);

        u64 (*peer_db_read_mask)(struct ntb_dev *ntb);
        int (*peer_db_set_mask)(struct ntb_dev *ntb, u64 db_bits);
        int (*peer_db_clear_mask)(struct ntb_dev *ntb, u64 db_bits);

        int (*spad_is_unsafe)(struct ntb_dev *ntb);
        int (*spad_count)(struct ntb_dev *ntb);

        u32 (*spad_read)(struct ntb_dev *ntb, int idx);
        int (*spad_write)(struct ntb_dev *ntb, int idx, u32 val);

        int (*peer_spad_addr)(struct ntb_dev *ntb, int idx,
                              phys_addr_t *spad_addr);
        u32 (*peer_spad_read)(struct ntb_dev *ntb, int idx);
        int (*peer_spad_write)(struct ntb_dev *ntb, int idx, u32 val);
};

static inline int ntb_dev_ops_is_valid(const struct ntb_dev_ops *ops)
{
        /* commented callbacks are not required: */
        return
                ops->mw_count                           &&
                ops->mw_get_range                       &&
                ops->mw_set_trans                       &&
                /* ops->mw_clear_trans                  && */
                ops->link_is_up                         &&
                ops->link_enable                        &&
                ops->link_disable                       &&
                /* ops->db_is_unsafe                    && */
                ops->db_valid_mask                      &&

                /* both set, or both unset */
                (!ops->db_vector_count == !ops->db_vector_mask) &&

                ops->db_read                            &&
                /* ops->db_set                          && */
                ops->db_clear                           &&
                /* ops->db_read_mask                    && */
                ops->db_set_mask                        &&
                ops->db_clear_mask                      &&
                /* ops->peer_db_addr                    && */
                /* ops->peer_db_read                    && */
                ops->peer_db_set                        &&
                /* ops->peer_db_clear                   && */
                /* ops->peer_db_read_mask               && */
                /* ops->peer_db_set_mask                && */
                /* ops->peer_db_clear_mask              && */
                /* ops->spad_is_unsafe                  && */
                ops->spad_count                         &&
                ops->spad_read                          &&
                ops->spad_write                         &&
                /* ops->peer_spad_addr                  && */
                /* ops->peer_spad_read                  && */
                ops->peer_spad_write                    &&
                1;
}

/**
 * struct ntb_client - client interested in ntb devices
 * @drv:                Linux driver object.
 * @ops:                See &ntb_client_ops.
 */
struct ntb_client {
        struct device_driver            drv;
        const struct ntb_client_ops     ops;
};

#define drv_ntb_client(__drv) container_of((__drv), struct ntb_client, drv)

/**
 * struct ntb_device - ntb device
 * @dev:                Linux device object.
 * @pdev:               Pci device entry of the ntb.
 * @topo:               Detected topology of the ntb.
 * @ops:                See &ntb_dev_ops.
 * @ctx:                See &ntb_ctx_ops.
 * @ctx_ops:            See &ntb_ctx_ops.
 */
struct ntb_dev {
        struct device                   dev;
        struct pci_dev                  *pdev;
        enum ntb_topo                   topo;
        const struct ntb_dev_ops        *ops;
        void                            *ctx;
        const struct ntb_ctx_ops        *ctx_ops;

        /* private: */

        /* synchronize setting, clearing, and calling ctx_ops */
        spinlock_t                      ctx_lock;
        /* block unregister until device is fully released */
        struct completion               released;
};

#define dev_ntb(__dev) container_of((__dev), struct ntb_dev, dev)

/**
 * ntb_register_client() - register a client for interest in ntb devices
 * @client:     Client context.
 *
 * The client will be added to the list of clients interested in ntb devices.
 * The client will be notified of any ntb devices that are not already
 * associated with a client, or if ntb devices are registered later.
 *
 * Return: Zero if the client is registered, otherwise an error number.
 */
#define ntb_register_client(client) \
        __ntb_register_client((client), THIS_MODULE, KBUILD_MODNAME)

int __ntb_register_client(struct ntb_client *client, struct module *mod,
                          const char *mod_name);

/**
 * ntb_unregister_client() - unregister a client for interest in ntb devices
 * @client:     Client context.
 *
 * The client will be removed from the list of clients interested in ntb
 * devices.  If any ntb devices are associated with the client, the client will
 * be notified to remove those devices.
 */
void ntb_unregister_client(struct ntb_client *client);

#define module_ntb_client(__ntb_client) \
        module_driver(__ntb_client, ntb_register_client, \
                        ntb_unregister_client)

/**
 * ntb_register_device() - register a ntb device
 * @ntb:        NTB device context.
 *
 * The device will be added to the list of ntb devices.  If any clients are
 * interested in ntb devices, each client will be notified of the ntb device,
 * until at most one client accepts the device.
 *
 * Return: Zero if the device is registered, otherwise an error number.
 */
int ntb_register_device(struct ntb_dev *ntb);

/**
 * ntb_register_device() - unregister a ntb device
 * @ntb:        NTB device context.
 *
 * The device will be removed from the list of ntb devices.  If the ntb device
 * is associated with a client, the client will be notified to remove the
 * device.
 */
void ntb_unregister_device(struct ntb_dev *ntb);

/**
 * ntb_set_ctx() - associate a driver context with an ntb device
 * @ntb:        NTB device context.
 * @ctx:        Driver context.
 * @ctx_ops:    Driver context operations.
 *
 * Associate a driver context and operations with a ntb device.  The context is
 * provided by the client driver, and the driver may associate a different
 * context with each ntb device.
 *
 * Return: Zero if the context is associated, otherwise an error number.
 */
int ntb_set_ctx(struct ntb_dev *ntb, void *ctx,
                const struct ntb_ctx_ops *ctx_ops);

/**
 * ntb_clear_ctx() - disassociate any driver context from an ntb device
 * @ntb:        NTB device context.
 *
 * Clear any association that may exist between a driver context and the ntb
 * device.
 */
void ntb_clear_ctx(struct ntb_dev *ntb);

/**
 * ntb_link_event() - notify driver context of a change in link status
 * @ntb:        NTB device context.
 *
 * Notify the driver context that the link status may have changed.  The driver
 * should call ntb_link_is_up() to get the current status.
 */
void ntb_link_event(struct ntb_dev *ntb);

/**
 * ntb_db_event() - notify driver context of a doorbell event
 * @ntb:        NTB device context.
 * @vector:     Interrupt vector number.
 *
 * Notify the driver context of a doorbell event.  If hardware supports
 * multiple interrupt vectors for doorbells, the vector number indicates which
 * vector received the interrupt.  The vector number is relative to the first
 * vector used for doorbells, starting at zero, and must be less than
 ** ntb_db_vector_count().  The driver may call ntb_db_read() to check which
 * doorbell bits need service, and ntb_db_vector_mask() to determine which of
 * those bits are associated with the vector number.
 */
void ntb_db_event(struct ntb_dev *ntb, int vector);

/**
 * ntb_mw_count() - get the number of memory windows
 * @ntb:        NTB device context.
 *
 * Hardware and topology may support a different number of memory windows.
 *
 * Return: the number of memory windows.
 */
static inline int ntb_mw_count(struct ntb_dev *ntb)
{
        return ntb->ops->mw_count(ntb);
}

/**
 * ntb_mw_get_range() - get the range of a memory window
 * @ntb:        NTB device context.
 * @idx:        Memory window number.
 * @base:       OUT - the base address for mapping the memory window
 * @size:       OUT - the size for mapping the memory window
 * @align:      OUT - the base alignment for translating the memory window
 * @align_size: OUT - the size alignment for translating the memory window
 *
 * Get the range of a memory window.  NULL may be given for any output
 * parameter if the value is not needed.  The base and size may be used for
 * mapping the memory window, to access the peer memory.  The alignment and
 * size may be used for translating the memory window, for the peer to access
 * memory on the local system.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_mw_get_range(struct ntb_dev *ntb, int idx,
                                   phys_addr_t *base, resource_size_t *size,
                resource_size_t *align, resource_size_t *align_size)
{
        return ntb->ops->mw_get_range(ntb, idx, base, size,
                        align, align_size);
}

/**
 * ntb_mw_set_trans() - set the translation of a memory window
 * @ntb:        NTB device context.
 * @idx:        Memory window number.
 * @addr:       The dma address local memory to expose to the peer.
 * @size:       The size of the local memory to expose to the peer.
 *
 * Set the translation of a memory window.  The peer may access local memory
 * through the window starting at the address, up to the size.  The address
 * must be aligned to the alignment specified by ntb_mw_get_range().  The size
 * must be aligned to the size alignment specified by ntb_mw_get_range().
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_mw_set_trans(struct ntb_dev *ntb, int idx,
                                   dma_addr_t addr, resource_size_t size)
{
        return ntb->ops->mw_set_trans(ntb, idx, addr, size);
}

/**
 * ntb_mw_clear_trans() - clear the translation of a memory window
 * @ntb:        NTB device context.
 * @idx:        Memory window number.
 *
 * Clear the translation of a memory window.  The peer may no longer access
 * local memory through the window.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_mw_clear_trans(struct ntb_dev *ntb, int idx)
{
        if (!ntb->ops->mw_clear_trans)
                return ntb->ops->mw_set_trans(ntb, idx, 0, 0);

        return ntb->ops->mw_clear_trans(ntb, idx);
}

/**
 * ntb_link_is_up() - get the current ntb link state
 * @ntb:        NTB device context.
 * @speed:      OUT - The link speed expressed as PCIe generation number.
 * @width:      OUT - The link width expressed as the number of PCIe lanes.
 *
 * Set the translation of a memory window.  The peer may access local memory
 * through the window starting at the address, up to the size.  The address
 * must be aligned to the alignment specified by ntb_mw_get_range().  The size
 * must be aligned to the size alignment specified by ntb_mw_get_range().
 *
 * Return: One if the link is up, zero if the link is down, otherwise a
 *              negative value indicating the error number.
 */
static inline int ntb_link_is_up(struct ntb_dev *ntb,
                                 enum ntb_speed *speed, enum ntb_width *width)
{
        return ntb->ops->link_is_up(ntb, speed, width);
}

/**
 * ntb_link_enable() - enable the link on the secondary side of the ntb
 * @ntb:        NTB device context.
 * @max_speed:  The maximum link speed expressed as PCIe generation number.
 * @max_width:  The maximum link width expressed as the number of PCIe lanes.
 *
 * Enable the link on the secondary side of the ntb.  This can only be done
 * from the primary side of the ntb in primary or b2b topology.  The ntb device
 * should train the link to its maximum speed and width, or the requested speed
 * and width, whichever is smaller, if supported.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_link_enable(struct ntb_dev *ntb,
                                  enum ntb_speed max_speed,
                                  enum ntb_width max_width)
{
        return ntb->ops->link_enable(ntb, max_speed, max_width);
}

/**
 * ntb_link_disable() - disable the link on the secondary side of the ntb
 * @ntb:        NTB device context.
 *
 * Disable the link on the secondary side of the ntb.  This can only be
 * done from the primary side of the ntb in primary or b2b topology.  The ntb
 * device should disable the link.  Returning from this call must indicate that
 * a barrier has passed, though with no more writes may pass in either
 * direction across the link, except if this call returns an error number.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_link_disable(struct ntb_dev *ntb)
{
        return ntb->ops->link_disable(ntb);
}

/**
 * ntb_db_is_unsafe() - check if it is safe to use hardware doorbell
 * @ntb:        NTB device context.
 *
 * It is possible for some ntb hardware to be affected by errata.  Hardware
 * drivers can advise clients to avoid using doorbells.  Clients may ignore
 * this advice, though caution is recommended.
 *
 * Return: Zero if it is safe to use doorbells, or One if it is not safe.
 */
static inline int ntb_db_is_unsafe(struct ntb_dev *ntb)
{
        if (!ntb->ops->db_is_unsafe)
                return 0;

        return ntb->ops->db_is_unsafe(ntb);
}

/**
 * ntb_db_valid_mask() - get a mask of doorbell bits supported by the ntb
 * @ntb:        NTB device context.
 *
 * Hardware may support different number or arrangement of doorbell bits.
 *
 * Return: A mask of doorbell bits supported by the ntb.
 */
static inline u64 ntb_db_valid_mask(struct ntb_dev *ntb)
{
        return ntb->ops->db_valid_mask(ntb);
}

/**
 * ntb_db_vector_count() - get the number of doorbell interrupt vectors
 * @ntb:        NTB device context.
 *
 * Hardware may support different number of interrupt vectors.
 *
 * Return: The number of doorbell interrupt vectors.
 */
static inline int ntb_db_vector_count(struct ntb_dev *ntb)
{
        if (!ntb->ops->db_vector_count)
                return 1;

        return ntb->ops->db_vector_count(ntb);
}

/**
 * ntb_db_vector_mask() - get a mask of doorbell bits serviced by a vector
 * @ntb:        NTB device context.
 * @vector:     Doorbell vector number.
 *
 * Each interrupt vector may have a different number or arrangement of bits.
 *
 * Return: A mask of doorbell bits serviced by a vector.
 */
static inline u64 ntb_db_vector_mask(struct ntb_dev *ntb, int vector)
{
        if (!ntb->ops->db_vector_mask)
                return ntb_db_valid_mask(ntb);

        return ntb->ops->db_vector_mask(ntb, vector);
}

/**
 * ntb_db_read() - read the local doorbell register
 * @ntb:        NTB device context.
 *
 * Read the local doorbell register, and return the bits that are set.
 *
 * Return: The bits currently set in the local doorbell register.
 */
static inline u64 ntb_db_read(struct ntb_dev *ntb)
{
        return ntb->ops->db_read(ntb);
}

/**
 * ntb_db_set() - set bits in the local doorbell register
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell bits to set.
 *
 * Set bits in the local doorbell register, which may generate a local doorbell
 * interrupt.  Bits that were already set must remain set.
 *
 * This is unusual, and hardware may not support it.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_db_set(struct ntb_dev *ntb, u64 db_bits)
{
        if (!ntb->ops->db_set)
                return -EINVAL;

        return ntb->ops->db_set(ntb, db_bits);
}

/**
 * ntb_db_clear() - clear bits in the local doorbell register
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell bits to clear.
 *
 * Clear bits in the local doorbell register, arming the bits for the next
 * doorbell.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_db_clear(struct ntb_dev *ntb, u64 db_bits)
{
        return ntb->ops->db_clear(ntb, db_bits);
}

/**
 * ntb_db_read_mask() - read the local doorbell mask
 * @ntb:        NTB device context.
 *
 * Read the local doorbell mask register, and return the bits that are set.
 *
 * This is unusual, though hardware is likely to support it.
 *
 * Return: The bits currently set in the local doorbell mask register.
 */
static inline u64 ntb_db_read_mask(struct ntb_dev *ntb)
{
        if (!ntb->ops->db_read_mask)
                return 0;

        return ntb->ops->db_read_mask(ntb);
}

/**
 * ntb_db_set_mask() - set bits in the local doorbell mask
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell mask bits to set.
 *
 * Set bits in the local doorbell mask register, preventing doorbell interrupts
 * from being generated for those doorbell bits.  Bits that were already set
 * must remain set.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_db_set_mask(struct ntb_dev *ntb, u64 db_bits)
{
        return ntb->ops->db_set_mask(ntb, db_bits);
}

/**
 * ntb_db_clear_mask() - clear bits in the local doorbell mask
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell bits to clear.
 *
 * Clear bits in the local doorbell mask register, allowing doorbell interrupts
 * from being generated for those doorbell bits.  If a doorbell bit is already
 * set at the time the mask is cleared, and the corresponding mask bit is
 * changed from set to clear, then the ntb driver must ensure that
 * ntb_db_event() is called.  If the hardware does not generate the interrupt
 * on clearing the mask bit, then the driver must call ntb_db_event() anyway.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_db_clear_mask(struct ntb_dev *ntb, u64 db_bits)
{
        return ntb->ops->db_clear_mask(ntb, db_bits);
}

/**
 * ntb_peer_db_addr() - address and size of the peer doorbell register
 * @ntb:        NTB device context.
 * @db_addr:    OUT - The address of the peer doorbell register.
 * @db_size:    OUT - The number of bytes to write the peer doorbell register.
 *
 * Return the address of the peer doorbell register.  This may be used, for
 * example, by drivers that offload memory copy operations to a dma engine.
 * The drivers may wish to ring the peer doorbell at the completion of memory
 * copy operations.  For efficiency, and to simplify ordering of operations
 * between the dma memory copies and the ringing doorbell, the driver may
 * append one additional dma memory copy with the doorbell register as the
 * destination, after the memory copy operations.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_peer_db_addr(struct ntb_dev *ntb,
                                   phys_addr_t *db_addr,
                                   resource_size_t *db_size)
{
        if (!ntb->ops->peer_db_addr)
                return -EINVAL;

        return ntb->ops->peer_db_addr(ntb, db_addr, db_size);
}

/**
 * ntb_peer_db_read() - read the peer doorbell register
 * @ntb:        NTB device context.
 *
 * Read the peer doorbell register, and return the bits that are set.
 *
 * This is unusual, and hardware may not support it.
 *
 * Return: The bits currently set in the peer doorbell register.
 */
static inline u64 ntb_peer_db_read(struct ntb_dev *ntb)
{
        if (!ntb->ops->peer_db_read)
                return 0;

        return ntb->ops->peer_db_read(ntb);
}

/**
 * ntb_peer_db_set() - set bits in the peer doorbell register
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell bits to set.
 *
 * Set bits in the peer doorbell register, which may generate a peer doorbell
 * interrupt.  Bits that were already set must remain set.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_peer_db_set(struct ntb_dev *ntb, u64 db_bits)
{
        return ntb->ops->peer_db_set(ntb, db_bits);
}

/**
 * ntb_peer_db_clear() - clear bits in the peer doorbell register
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell bits to clear.
 *
 * Clear bits in the peer doorbell register, arming the bits for the next
 * doorbell.
 *
 * This is unusual, and hardware may not support it.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_peer_db_clear(struct ntb_dev *ntb, u64 db_bits)
{
        if (!ntb->ops->db_clear)
                return -EINVAL;

        return ntb->ops->peer_db_clear(ntb, db_bits);
}

/**
 * ntb_peer_db_read_mask() - read the peer doorbell mask
 * @ntb:        NTB device context.
 *
 * Read the peer doorbell mask register, and return the bits that are set.
 *
 * This is unusual, and hardware may not support it.
 *
 * Return: The bits currently set in the peer doorbell mask register.
 */
static inline u64 ntb_peer_db_read_mask(struct ntb_dev *ntb)
{
        if (!ntb->ops->db_read_mask)
                return 0;

        return ntb->ops->peer_db_read_mask(ntb);
}

/**
 * ntb_peer_db_set_mask() - set bits in the peer doorbell mask
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell mask bits to set.
 *
 * Set bits in the peer doorbell mask register, preventing doorbell interrupts
 * from being generated for those doorbell bits.  Bits that were already set
 * must remain set.
 *
 * This is unusual, and hardware may not support it.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_peer_db_set_mask(struct ntb_dev *ntb, u64 db_bits)
{
        if (!ntb->ops->db_set_mask)
                return -EINVAL;

        return ntb->ops->peer_db_set_mask(ntb, db_bits);
}

/**
 * ntb_peer_db_clear_mask() - clear bits in the peer doorbell mask
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell bits to clear.
 *
 * Clear bits in the peer doorbell mask register, allowing doorbell interrupts
 * from being generated for those doorbell bits.  If the hardware does not
 * generate the interrupt on clearing the mask bit, then the driver should not
 * implement this function!
 *
 * This is unusual, and hardware may not support it.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_peer_db_clear_mask(struct ntb_dev *ntb, u64 db_bits)
{
        if (!ntb->ops->db_clear_mask)
                return -EINVAL;

        return ntb->ops->peer_db_clear_mask(ntb, db_bits);
}

/**
 * ntb_spad_is_unsafe() - check if it is safe to use the hardware scratchpads
 * @ntb:        NTB device context.
 *
 * It is possible for some ntb hardware to be affected by errata.  Hardware
 * drivers can advise clients to avoid using scratchpads.  Clients may ignore
 * this advice, though caution is recommended.
 *
 * Return: Zero if it is safe to use scratchpads, or One if it is not safe.
 */
static inline int ntb_spad_is_unsafe(struct ntb_dev *ntb)
{
        if (!ntb->ops->spad_is_unsafe)
                return 0;

        return ntb->ops->spad_is_unsafe(ntb);
}

/**
 * ntb_spad_count() - get the number of scratchpads
 * @ntb:        NTB device context.
 *
 * Hardware and topology may support a different number of scratchpads.
 *
 * Return: the number of scratchpads.
 */
static inline int ntb_spad_count(struct ntb_dev *ntb)
{
        return ntb->ops->spad_count(ntb);
}

/**
 * ntb_spad_read() - read the local scratchpad register
 * @ntb:        NTB device context.
 * @idx:        Scratchpad index.
 *
 * Read the local scratchpad register, and return the value.
 *
 * Return: The value of the local scratchpad register.
 */
static inline u32 ntb_spad_read(struct ntb_dev *ntb, int idx)
{
        return ntb->ops->spad_read(ntb, idx);
}

/**
 * ntb_spad_write() - write the local scratchpad register
 * @ntb:        NTB device context.
 * @idx:        Scratchpad index.
 * @val:        Scratchpad value.
 *
 * Write the value to the local scratchpad register.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_spad_write(struct ntb_dev *ntb, int idx, u32 val)
{
        return ntb->ops->spad_write(ntb, idx, val);
}

/**
 * ntb_peer_spad_addr() - address of the peer scratchpad register
 * @ntb:        NTB device context.
 * @idx:        Scratchpad index.
 * @spad_addr:  OUT - The address of the peer scratchpad register.
 *
 * Return the address of the peer doorbell register.  This may be used, for
 * example, by drivers that offload memory copy operations to a dma engine.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_peer_spad_addr(struct ntb_dev *ntb, int idx,
                                     phys_addr_t *spad_addr)
{
        if (!ntb->ops->peer_spad_addr)
                return -EINVAL;

        return ntb->ops->peer_spad_addr(ntb, idx, spad_addr);
}

/**
 * ntb_peer_spad_read() - read the peer scratchpad register
 * @ntb:        NTB device context.
 * @idx:        Scratchpad index.
 *
 * Read the peer scratchpad register, and return the value.
 *
 * Return: The value of the local scratchpad register.
 */
static inline u32 ntb_peer_spad_read(struct ntb_dev *ntb, int idx)
{
        if (!ntb->ops->peer_spad_read)
                return 0;

        return ntb->ops->peer_spad_read(ntb, idx);
}

/**
 * ntb_peer_spad_write() - write the peer scratchpad register
 * @ntb:        NTB device context.
 * @idx:        Scratchpad index.
 * @val:        Scratchpad value.
 *
 * Write the value to the peer scratchpad register.
 *
 * Return: Zero on success, otherwise an error number.
 */
static inline int ntb_peer_spad_write(struct ntb_dev *ntb, int idx, u32 val)
{
        return ntb->ops->peer_spad_write(ntb, idx, val);
}

#endif