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 void 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
  71 int 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 }
  79 EXPORT_SYMBOL_GPL(register_cxl_calls);
  80
  81 void 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 }
  87 EXPORT_SYMBOL_GPL(unregister_cxl_calls);
  88
  89 int cxl_update_properties(struct device_node *dn,
  90                           struct property *new_prop)
  91 {
  92         return of_update_property(dn, new_prop);
  93 }
  94 EXPORT_SYMBOL_GPL(cxl_update_properties);
  95
  96 static 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
 118 module_init(cxl_base_init);