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);