drivers/misc/cxl/base.c

   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_platform.h>
  11 #include "cxl.h"
  12
  13 /* protected by rcu */
  14 static struct cxl_calls *cxl_calls;
  15
  16 atomic_t cxl_use_count = ATOMIC_INIT(0);
  17 EXPORT_SYMBOL(cxl_use_count);
  18
  19 #ifdef CONFIG_CXL_MODULE
  20
  21 static inline struct cxl_calls *cxl_calls_get(void)
  22 {
  23         struct cxl_calls *calls = NULL;
  24
  25         rcu_read_lock();
  26         calls = rcu_dereference(cxl_calls);
  27         if (calls && !try_module_get(calls->owner))
  28                 calls = NULL;
  29         rcu_read_unlock();
  30
  31         return calls;
  32 }
  33
  34 static inline void cxl_calls_put(struct cxl_calls *calls)
  35 {
  36         BUG_ON(calls != cxl_calls);
  37
  38         /* we don't need to rcu this, as we hold a reference to the module */
  39         module_put(cxl_calls->owner);
  40 }
  41
  42 #else /* !defined CONFIG_CXL_MODULE */
  43
  44 static inline struct cxl_calls *cxl_calls_get(void)
  45 {
  46         return cxl_calls;
  47 }
  48
  49 static inline void cxl_calls_put(struct cxl_calls *calls) { }
  50
  51 #endif /* CONFIG_CXL_MODULE */
  52
  53 /* AFU refcount management */
  54 struct cxl_afu *cxl_afu_get(struct cxl_afu *afu)
  55 {
  56         return (get_device(&afu->dev) == NULL) ? NULL : afu;
  57 }
  58 EXPORT_SYMBOL_GPL(cxl_afu_get);
  59
  60 void cxl_afu_put(struct cxl_afu *afu)
  61 {
  62         put_device(&afu->dev);
  63 }
  64 EXPORT_SYMBOL_GPL(cxl_afu_put);
  65
  66 void cxl_slbia(struct mm_struct *mm)
  67 {
  68         struct cxl_calls *calls;
  69
  70         calls = cxl_calls_get();
  71         if (!calls)
  72                 return;
  73
  74         if (cxl_ctx_in_use())
  75             calls->cxl_slbia(mm);
  76
  77         cxl_calls_put(calls);
  78 }
  79
  80 int register_cxl_calls(struct cxl_calls *calls)
  81 {
  82         if (cxl_calls)
  83                 return -EBUSY;
  84
  85         rcu_assign_pointer(cxl_calls, calls);
  86         return 0;
  87 }
  88 EXPORT_SYMBOL_GPL(register_cxl_calls);
  89
  90 void unregister_cxl_calls(struct cxl_calls *calls)
  91 {
  92         BUG_ON(cxl_calls->owner != calls->owner);
  93         RCU_INIT_POINTER(cxl_calls, NULL);
  94         synchronize_rcu();
  95 }
  96 EXPORT_SYMBOL_GPL(unregister_cxl_calls);
  97
  98 int cxl_update_properties(struct device_node *dn,
  99                           struct property *new_prop)
 100 {
 101         return of_update_property(dn, new_prop);
 102 }
 103 EXPORT_SYMBOL_GPL(cxl_update_properties);
 104
 105 static int __init cxl_base_init(void)
 106 {
 107         struct device_node *np;
 108         struct platform_device *dev;
 109         int count = 0;
 110
 111         /*
 112          * Scan for compatible devices in guest only
 113          */
 114         if (cpu_has_feature(CPU_FTR_HVMODE))
 115                 return 0;
 116
 117         for_each_compatible_node(np, NULL, "ibm,coherent-platform-facility") {
 118                 dev = of_platform_device_create(np, NULL, NULL);
 119                 if (dev)
 120                         count++;
 121         }
 122         pr_devel("Found %d cxl device(s)\n", count);
 123         return 0;
 124 }
 125 device_initcall(cxl_base_init);