1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 2014 IBM Corp.
4 */
5
6#include <linux/module.h>
7#include <linux/rcupdate.h>
8#include <asm/errno.h>
9#include <misc/cxl-base.h>
10#include <linux/of.h>
11#include <linux/of_platform.h>
12#include "cxl.h"
13
14/* protected by rcu */
15static struct cxl_calls *cxl_calls;
16
17atomic_t cxl_use_count = ATOMIC_INIT(0);
18EXPORT_SYMBOL(cxl_use_count);
19
20#ifdef CONFIG_CXL_MODULE
21
22static inline struct cxl_calls *cxl_calls_get(void)
23{
24	struct cxl_calls *calls = NULL;
25
26	rcu_read_lock();
27	calls = rcu_dereference(cxl_calls);
28	if (calls && !try_module_get(calls->owner))
29		calls = NULL;
30	rcu_read_unlock();
31
32	return calls;
33}
34
35static inline void cxl_calls_put(struct cxl_calls *calls)
36{
37	BUG_ON(calls != cxl_calls);
38
39	/* we don't need to rcu this, as we hold a reference to the module */
40	module_put(cxl_calls->owner);
41}
42
43#else /* !defined CONFIG_CXL_MODULE */
44
45static inline struct cxl_calls *cxl_calls_get(void)
46{
47	return cxl_calls;
48}
49
50static inline void cxl_calls_put(struct cxl_calls *calls) { }
51
52#endif /* CONFIG_CXL_MODULE */
53
54/* AFU refcount management */
55struct cxl_afu *cxl_afu_get(struct cxl_afu *afu)
56{
57	return (get_device(&afu->dev) == NULL) ? NULL : afu;
58}
59EXPORT_SYMBOL_GPL(cxl_afu_get);
60
61void cxl_afu_put(struct cxl_afu *afu)
62{
63	put_device(&afu->dev);
64}
65EXPORT_SYMBOL_GPL(cxl_afu_put);
66
67void cxl_slbia(struct mm_struct *mm)
68{
69	struct cxl_calls *calls;
70
71	calls = cxl_calls_get();
72	if (!calls)
73		return;
74
75	if (cxl_ctx_in_use())
76	    calls->cxl_slbia(mm);
77
78	cxl_calls_put(calls);
79}
80
81int register_cxl_calls(struct cxl_calls *calls)
82{
83	if (cxl_calls)
84		return -EBUSY;
85
86	rcu_assign_pointer(cxl_calls, calls);
87	return 0;
88}
89EXPORT_SYMBOL_GPL(register_cxl_calls);
90
91void unregister_cxl_calls(struct cxl_calls *calls)
92{
93	BUG_ON(cxl_calls->owner != calls->owner);
94	RCU_INIT_POINTER(cxl_calls, NULL);
95	synchronize_rcu();
96}
97EXPORT_SYMBOL_GPL(unregister_cxl_calls);
98
99int cxl_update_properties(struct device_node *dn,
100			  struct property *new_prop)
101{
102	return of_update_property(dn, new_prop);
103}
104EXPORT_SYMBOL_GPL(cxl_update_properties);
105
106static int __init cxl_base_init(void)
107{
108	struct device_node *np;
109	struct platform_device *dev;
110	int count = 0;
111
112	/*
113	 * Scan for compatible devices in guest only
114	 */
115	if (cpu_has_feature(CPU_FTR_HVMODE))
116		return 0;
117
118	for_each_compatible_node(np, NULL, "ibm,coherent-platform-facility") {
119		dev = of_platform_device_create(np, NULL, NULL);
120		if (dev)
121			count++;
122	}
123	pr_devel("Found %d cxl device(s)\n", count);
124	return 0;
125}
126device_initcall(cxl_base_init);
127