1/*
2 * Copyright 2014 IBM Corp.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 */
9
10#include <linux/module.h>
11#include <linux/rcupdate.h>
12#include <asm/errno.h>
13#include <misc/cxl.h>
14#include "cxl.h"
15
16/* protected by rcu */
17static struct cxl_calls *cxl_calls;
18
19atomic_t cxl_use_count = ATOMIC_INIT(0);
20EXPORT_SYMBOL(cxl_use_count);
21
22#ifdef CONFIG_CXL_MODULE
23
24static inline struct cxl_calls *cxl_calls_get(void)
25{
26	struct cxl_calls *calls = NULL;
27
28	rcu_read_lock();
29	calls = rcu_dereference(cxl_calls);
30	if (calls && !try_module_get(calls->owner))
31		calls = NULL;
32	rcu_read_unlock();
33
34	return calls;
35}
36
37static inline void cxl_calls_put(struct cxl_calls *calls)
38{
39	BUG_ON(calls != cxl_calls);
40
41	/* we don't need to rcu this, as we hold a reference to the module */
42	module_put(cxl_calls->owner);
43}
44
45#else /* !defined CONFIG_CXL_MODULE */
46
47static inline struct cxl_calls *cxl_calls_get(void)
48{
49	return cxl_calls;
50}
51
52static inline void cxl_calls_put(struct cxl_calls *calls) { }
53
54#endif /* CONFIG_CXL_MODULE */
55
56void cxl_slbia(struct mm_struct *mm)
57{
58	struct cxl_calls *calls;
59
60	calls = cxl_calls_get();
61	if (!calls)
62		return;
63
64	if (cxl_ctx_in_use())
65	    calls->cxl_slbia(mm);
66
67	cxl_calls_put(calls);
68}
69
70int register_cxl_calls(struct cxl_calls *calls)
71{
72	if (cxl_calls)
73		return -EBUSY;
74
75	rcu_assign_pointer(cxl_calls, calls);
76	return 0;
77}
78EXPORT_SYMBOL_GPL(register_cxl_calls);
79
80void unregister_cxl_calls(struct cxl_calls *calls)
81{
82	BUG_ON(cxl_calls->owner != calls->owner);
83	RCU_INIT_POINTER(cxl_calls, NULL);
84	synchronize_rcu();
85}
86EXPORT_SYMBOL_GPL(unregister_cxl_calls);
87