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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Direct Internal Buffer Sharing
*
* Definitions for the DIBS module
*
* Copyright IBM Corp. 2025
*/
#ifndef _DIBS_H
#define _DIBS_H
#include <linux/device.h>
/* DIBS - Direct Internal Buffer Sharing - concept
* -----------------------------------------------
* In the case of multiple system sharing the same hardware, dibs fabrics can
* provide dibs devices to these systems. The systems use dibs devices of the
* same fabric to communicate via dmbs (Direct Memory Buffers). Each dmb has
* exactly one owning local dibs device and one remote using dibs device, that
* is authorized to write into this dmb. This access control is provided by the
* dibs fabric.
*
* Because the access to the dmb is based on access to physical memory, it is
* lossless and synchronous. The remote devices can directly access any offset
* of the dmb.
*
* Dibs fabrics, dibs devices and dmbs are identified by tokens and ids.
* Dibs fabric id is unique within the same hardware (with the exception of the
* dibs loopback fabric), dmb token is unique within the same fabric, dibs
* device gids are guaranteed to be unique within the same fabric and
* statistically likely to be globally unique. The exchange of these tokens and
* ids between the systems is not part of the dibs concept.
*
* The dibs layer provides an abstraction between dibs device drivers and dibs
* clients.
*/
/* DIBS client
* -----------
*/
#define MAX_DIBS_CLIENTS 8
struct dibs_client {
/* client name for logging and debugging purposes */
const char *name;
/* client index - provided and used by dibs layer */
u8 id;
};
/* Functions to be called by dibs clients:
*/
/**
* dibs_register_client() - register a client with dibs layer
* @client: this client
*
* Return: zero on success.
*/
int dibs_register_client(struct dibs_client *client);
/**
* dibs_unregister_client() - unregister a client with dibs layer
* @client: this client
*
* Return: zero on success.
*/
int dibs_unregister_client(struct dibs_client *client);
/* DIBS devices
* ------------
*/
struct dibs_dev {
struct list_head list;
};
/* ------- End of client-only functions ----------- */
/*
* Functions to be called by dibs device drivers:
*/
/**
* dibs_dev_alloc() - allocate and reference device structure
*
* The following fields will be valid upon successful return: dev
* NOTE: Use put_device(dibs_get_dev(@dibs)) to give up your reference instead
* of freeing @dibs @dev directly once you have successfully called this
* function.
* Return: Pointer to dibs device structure
*/
struct dibs_dev *dibs_dev_alloc(void);
/**
* dibs_dev_add() - register with dibs layer and all clients
* @dibs: dibs device
*
* The following fields must be valid upon entry: dev, ops, drv_priv
* All fields will be valid upon successful return.
* Return: zero on success
*/
int dibs_dev_add(struct dibs_dev *dibs);
/**
* dibs_dev_del() - unregister from dibs layer and all clients
* @dibs: dibs device
*/
void dibs_dev_del(struct dibs_dev *dibs);
#endif /* _DIBS_H */
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