drivers/misc/cxl/base.c

   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);