xref: /kernel/linux/linux-5.10/drivers/misc/cxl/base.c (revision 8c2ecf20) 
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_platform.h>
11#include "cxl.h"
12
13/* protected by rcu */
14static struct cxl_calls *cxl_calls;
15
16atomic_t cxl_use_count = ATOMIC_INIT(0);
17EXPORT_SYMBOL(cxl_use_count);
18
19#ifdef CONFIG_CXL_MODULE
20
21static inline struct cxl_calls *cxl_calls_get(void)
22{
23	struct cxl_calls *calls = NULL;
24
25	rcu_read_lock();
26	calls = rcu_dereference(cxl_calls);
27	if (calls && !try_module_get(calls->owner))
28		calls = NULL;
29	rcu_read_unlock();
30
31	return calls;
32}
33
34static inline void cxl_calls_put(struct cxl_calls *calls)
35{
36	BUG_ON(calls != cxl_calls);
37
38	/* we don't need to rcu this, as we hold a reference to the module */
39	module_put(cxl_calls->owner);
40}
41
42#else /* !defined CONFIG_CXL_MODULE */
43
44static inline struct cxl_calls *cxl_calls_get(void)
45{
46	return cxl_calls;
47}
48
49static inline void cxl_calls_put(struct cxl_calls *calls) { }
50
51#endif /* CONFIG_CXL_MODULE */
52
53/* AFU refcount management */
54struct cxl_afu *cxl_afu_get(struct cxl_afu *afu)
55{
56	return (get_device(&afu->dev) == NULL) ? NULL : afu;
57}
58EXPORT_SYMBOL_GPL(cxl_afu_get);
59
60void cxl_afu_put(struct cxl_afu *afu)
61{
62	put_device(&afu->dev);
63}
64EXPORT_SYMBOL_GPL(cxl_afu_put);
65
66void cxl_slbia(struct mm_struct *mm)
67{
68	struct cxl_calls *calls;
69
70	calls = cxl_calls_get();
71	if (!calls)
72		return;
73
74	if (cxl_ctx_in_use())
75	    calls->cxl_slbia(mm);
76
77	cxl_calls_put(calls);
78}
79
80int register_cxl_calls(struct cxl_calls *calls)
81{
82	if (cxl_calls)
83		return -EBUSY;
84
85	rcu_assign_pointer(cxl_calls, calls);
86	return 0;
87}
88EXPORT_SYMBOL_GPL(register_cxl_calls);
89
90void unregister_cxl_calls(struct cxl_calls *calls)
91{
92	BUG_ON(cxl_calls->owner != calls->owner);
93	RCU_INIT_POINTER(cxl_calls, NULL);
94	synchronize_rcu();
95}
96EXPORT_SYMBOL_GPL(unregister_cxl_calls);
97
98int cxl_update_properties(struct device_node *dn,
99			  struct property *new_prop)
100{
101	return of_update_property(dn, new_prop);
102}
103EXPORT_SYMBOL_GPL(cxl_update_properties);
104
105static int __init cxl_base_init(void)
106{
107	struct device_node *np;
108	struct platform_device *dev;
109	int count = 0;
110
111	/*
112	 * Scan for compatible devices in guest only
113	 */
114	if (cpu_has_feature(CPU_FTR_HVMODE))
115		return 0;
116
117	for_each_compatible_node(np, NULL, "ibm,coherent-platform-facility") {
118		dev = of_platform_device_create(np, NULL, NULL);
119		if (dev)
120			count++;
121	}
122	pr_devel("Found %d cxl device(s)\n", count);
123	return 0;
124}
125device_initcall(cxl_base_init);
126