dibs: Create drivers/dibs

Create the file structure for a 'DIBS - Direct Internal Buffer Sharing'
shim layer that will provide generic functionality and declarations for
dibs device drivers and dibs clients.

Following patches will add functionality.

Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Link: https://patch.msgid.link/20250918110500.1731261-4-wintera@linux.ibm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/dibs/Kconfig

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+config DIBS
+	tristate "DIBS support"
+	default n
+	help
+	  Direct Internal Buffer Sharing (DIBS)
+	  A communication method that uses common physical (internal) memory
+	  for synchronous direct access into a remote buffer.
+
+	  Select this option to provide the abstraction layer between
+	  dibs devices and dibs clients like the SMC protocol.
+	  The module name is dibs.

drivers/dibs/Makefile

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# DIBS class module
+#
+
+dibs-y += dibs_main.o
+obj-$(CONFIG_DIBS) += dibs.o

drivers/dibs/dibs_main.c

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  DIBS - Direct Internal Buffer Sharing
+ *
+ *  Implementation of the DIBS class module
+ *
+ *  Copyright IBM Corp. 2025
+ */
+#define KMSG_COMPONENT "dibs"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/dibs.h>
+
+MODULE_DESCRIPTION("Direct Internal Buffer Sharing class");
+MODULE_LICENSE("GPL");
+
+/* use an array rather a list for fast mapping: */
+static struct dibs_client *clients[MAX_DIBS_CLIENTS];
+static u8 max_client;
+
+static int __init dibs_init(void)
+{
+	memset(clients, 0, sizeof(clients));
+	max_client = 0;
+
+	return 0;
+}
+
+static void __exit dibs_exit(void)
+{
+}
+
+module_init(dibs_init);
+module_exit(dibs_exit);