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.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
  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
  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
  45 static inline struct cxl_calls *cxl_calls_get(void)
  46 {
  47         return cxl_calls;
  48 }
  49
  50 static inline void cxl_calls_put(struct cxl_calls *calls) { }
  51
  52 #endif /* CONFIG_CXL_MODULE */
  53
  54 /* AFU refcount management */
  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
  61 void cxl_afu_put(struct cxl_afu *afu)
  62 {
  63         put_device(&afu->dev);
  64 }
  65 EXPORT_SYMBOL_GPL(cxl_afu_put);
  66
  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
  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
  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
  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
 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);