xref: /linux/drivers/misc/cxl/base.c (revision a1c613ae4c322ddd58d5a8539dbfba2a0380a8c0)
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 */
15 static struct cxl_calls *cxl_calls;
16 
17 atomic_t cxl_use_count = ATOMIC_INIT(0);
18 EXPORT_SYMBOL(cxl_use_count);
19 
20 #ifdef CONFIG_CXL_MODULE
21 
cxl_calls_get(void)22 static 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 
cxl_calls_put(struct cxl_calls * calls)35 static 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 
cxl_calls_get(void)45 static inline struct cxl_calls *cxl_calls_get(void)
46 {
47 	return cxl_calls;
48 }
49 
cxl_calls_put(struct cxl_calls * calls)50 static inline void cxl_calls_put(struct cxl_calls *calls) { }
51 
52 #endif /* CONFIG_CXL_MODULE */
53 
54 /* AFU refcount management */
cxl_afu_get(struct cxl_afu * afu)55 struct cxl_afu *cxl_afu_get(struct cxl_afu *afu)
56 {
57 	return (get_device(&afu->dev) == NULL) ? NULL : afu;
58 }
59 EXPORT_SYMBOL_GPL(cxl_afu_get);
60 
cxl_afu_put(struct cxl_afu * afu)61 void cxl_afu_put(struct cxl_afu *afu)
62 {
63 	put_device(&afu->dev);
64 }
65 EXPORT_SYMBOL_GPL(cxl_afu_put);
66 
cxl_slbia(struct mm_struct * mm)67 void 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 
register_cxl_calls(struct cxl_calls * calls)81 int 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 }
89 EXPORT_SYMBOL_GPL(register_cxl_calls);
90 
unregister_cxl_calls(struct cxl_calls * calls)91 void 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 }
97 EXPORT_SYMBOL_GPL(unregister_cxl_calls);
98 
cxl_update_properties(struct device_node * dn,struct property * new_prop)99 int cxl_update_properties(struct device_node *dn,
100 			  struct property *new_prop)
101 {
102 	return of_update_property(dn, new_prop);
103 }
104 EXPORT_SYMBOL_GPL(cxl_update_properties);
105 
cxl_base_init(void)106 static 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 }
126 device_initcall(cxl_base_init);
127