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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-base.h>
14 #include <linux/of_platform.h>
15 #include "cxl.h"
16
17 /* protected by rcu */
18 static struct cxl_calls *cxl_calls;
19
20 atomic_t cxl_use_count = ATOMIC_INIT(0);
21 EXPORT_SYMBOL(cxl_use_count);
22
23 #ifdef CONFIG_CXL_MODULE
24
25 static inline struct cxl_calls *cxl_calls_get(void)
26 {
27 struct cxl_calls *calls = NULL;
28
29 rcu_read_lock();
30 calls = rcu_dereference(cxl_calls);
31 if (calls && !try_module_get(calls->owner))
32 calls = NULL;
33 rcu_read_unlock();
34
35 return calls;
36 }
37
38 static inline void cxl_calls_put(struct cxl_calls *calls)
39 {
40 BUG_ON(calls != cxl_calls);
41
42 /* we don't need to rcu this, as we hold a reference to the module */
43 module_put(cxl_calls->owner);
44 }
45
46 #else /* !defined CONFIG_CXL_MODULE */
47
48 static inline struct cxl_calls *cxl_calls_get(void)
49 {
50 return cxl_calls;
51 }
52
53 static inline void cxl_calls_put(struct cxl_calls *calls) { }
54
55 #endif /* CONFIG_CXL_MODULE */
56
57 /* AFU refcount management */
58 struct cxl_afu *cxl_afu_get(struct cxl_afu *afu)
59 {
60 return (get_device(&afu->dev) == NULL) ? NULL : afu;
61 }
62 EXPORT_SYMBOL_GPL(cxl_afu_get);
63
64 void cxl_afu_put(struct cxl_afu *afu)
65 {
66 put_device(&afu->dev);
67 }
68 EXPORT_SYMBOL_GPL(cxl_afu_put);
69
70 void cxl_slbia(struct mm_struct *mm)
71 {
72 struct cxl_calls *calls;
73
74 calls = cxl_calls_get();
75 if (!calls)
76 return;
77
78 if (cxl_ctx_in_use())
79 calls->cxl_slbia(mm);
80
81 cxl_calls_put(calls);
82 }
83
84 int register_cxl_calls(struct cxl_calls *calls)
85 {
86 if (cxl_calls)
87 return -EBUSY;
88
89 rcu_assign_pointer(cxl_calls, calls);
90 return 0;
91 }
92 EXPORT_SYMBOL_GPL(register_cxl_calls);
93
94 void unregister_cxl_calls(struct cxl_calls *calls)
95 {
96 BUG_ON(cxl_calls->owner != calls->owner);
97 RCU_INIT_POINTER(cxl_calls, NULL);
98 synchronize_rcu();
99 }
100 EXPORT_SYMBOL_GPL(unregister_cxl_calls);
101
102 int cxl_update_properties(struct device_node *dn,
103 struct property *new_prop)
104 {
105 return of_update_property(dn, new_prop);
106 }
107 EXPORT_SYMBOL_GPL(cxl_update_properties);
108
109 static int __init cxl_base_init(void)
110 {
111 struct device_node *np;
112 struct platform_device *dev;
113 int count = 0;
114
115 /*
116 * Scan for compatible devices in guest only
117 */
118 if (cpu_has_feature(CPU_FTR_HVMODE))
119 return 0;
120
121 for_each_compatible_node(np, NULL, "ibm,coherent-platform-facility") {
122 dev = of_platform_device_create(np, NULL, NULL);
123 if (dev)
124 count++;
125 }
126 pr_devel("Found %d cxl device(s)\n", count);
127 return 0;
128 }
129 device_initcall(cxl_base_init);