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 */
 18static struct cxl_calls *cxl_calls;
 19
 20atomic_t cxl_use_count = ATOMIC_INIT(0);
 21EXPORT_SYMBOL(cxl_use_count);
 22
 23#ifdef CONFIG_CXL_MODULE
 24
 25static 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
 38static 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
 48static inline struct cxl_calls *cxl_calls_get(void)
 49{
 50	return cxl_calls;
 51}
 52
 53static inline void cxl_calls_put(struct cxl_calls *calls) { }
 54
 55#endif /* CONFIG_CXL_MODULE */
 56
 57void cxl_slbia(struct mm_struct *mm)
 58{
 59	struct cxl_calls *calls;
 60
 61	calls = cxl_calls_get();
 62	if (!calls)
 63		return;
 64
 65	if (cxl_ctx_in_use())
 66	    calls->cxl_slbia(mm);
 67
 68	cxl_calls_put(calls);
 69}
 70
 71int register_cxl_calls(struct cxl_calls *calls)
 72{
 73	if (cxl_calls)
 74		return -EBUSY;
 75
 76	rcu_assign_pointer(cxl_calls, calls);
 77	return 0;
 78}
 79EXPORT_SYMBOL_GPL(register_cxl_calls);
 80
 81void unregister_cxl_calls(struct cxl_calls *calls)
 82{
 83	BUG_ON(cxl_calls->owner != calls->owner);
 84	RCU_INIT_POINTER(cxl_calls, NULL);
 85	synchronize_rcu();
 86}
 87EXPORT_SYMBOL_GPL(unregister_cxl_calls);
 88
 89int cxl_update_properties(struct device_node *dn,
 90			  struct property *new_prop)
 91{
 92	return of_update_property(dn, new_prop);
 93}
 94EXPORT_SYMBOL_GPL(cxl_update_properties);
 95
 96static int __init cxl_base_init(void)
 97{
 98	struct device_node *np = NULL;
 99	struct platform_device *dev;
100	int count = 0;
101
102	/*
103	 * Scan for compatible devices in guest only
104	 */
105	if (cpu_has_feature(CPU_FTR_HVMODE))
106		return 0;
107
108	while ((np = of_find_compatible_node(np, NULL,
109				     "ibm,coherent-platform-facility"))) {
110		dev = of_platform_device_create(np, NULL, NULL);
111		if (dev)
112			count++;
113	}
114	pr_devel("Found %d cxl device(s)\n", count);
115	return 0;
116}
117
118module_init(cxl_base_init);