drivers/misc/pvpanic/pvpanic.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  Pvpanic Device Support
   4  *
   5  *  Copyright (C) 2013 Fujitsu.
   6  *  Copyright (C) 2018 ZTE.
   7  *  Copyright (C) 2021 Oracle.
   8  */
   9
  10 #include <linux/io.h>
  11 #include <linux/kernel.h>
  12 #include <linux/kexec.h>
  13 #include <linux/mod_devicetable.h>
  14 #include <linux/module.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/panic_notifier.h>
  17 #include <linux/types.h>
  18 #include <linux/cdev.h>
  19 #include <linux/list.h>
  20
  21 #include <uapi/misc/pvpanic.h>
  22
  23 #include "pvpanic.h"
  24
  25 MODULE_AUTHOR("Mihai Carabas <mihai.carabas@oracle.com>");
  26 MODULE_DESCRIPTION("pvpanic device driver");
  27 MODULE_LICENSE("GPL");
  28
  29 static struct list_head pvpanic_list;
  30 static spinlock_t pvpanic_lock;
  31
  32 static void
  33 pvpanic_send_event(unsigned int event)
  34 {
  35         struct pvpanic_instance *pi_cur;
  36
  37         if (!spin_trylock(&pvpanic_lock))
  38                 return;
  39
  40         list_for_each_entry(pi_cur, &pvpanic_list, list) {
  41                 if (event & pi_cur->capability & pi_cur->events)
  42                         iowrite8(event, pi_cur->base);
  43         }
  44         spin_unlock(&pvpanic_lock);
  45 }
  46
  47 static int
  48 pvpanic_panic_notify(struct notifier_block *nb, unsigned long code, void *unused)
  49 {
  50         unsigned int event = PVPANIC_PANICKED;
  51
  52         if (kexec_crash_loaded())
  53                 event = PVPANIC_CRASH_LOADED;
  54
  55         pvpanic_send_event(event);
  56
  57         return NOTIFY_DONE;
  58 }
  59
  60 /*
  61  * Call our notifier very early on panic, deferring the
  62  * action taken to the hypervisor.
  63  */
  64 static struct notifier_block pvpanic_panic_nb = {
  65         .notifier_call = pvpanic_panic_notify,
  66         .priority = INT_MAX,
  67 };
  68
  69 static void pvpanic_remove(void *param)
  70 {
  71         struct pvpanic_instance *pi_cur, *pi_next;
  72         struct pvpanic_instance *pi = param;
  73
  74         spin_lock(&pvpanic_lock);
  75         list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) {
  76                 if (pi_cur == pi) {
  77                         list_del(&pi_cur->list);
  78                         break;
  79                 }
  80         }
  81         spin_unlock(&pvpanic_lock);
  82 }
  83
  84 int devm_pvpanic_probe(struct device *dev, struct pvpanic_instance *pi)
  85 {
  86         if (!pi || !pi->base)
  87                 return -EINVAL;
  88
  89         spin_lock(&pvpanic_lock);
  90         list_add(&pi->list, &pvpanic_list);
  91         spin_unlock(&pvpanic_lock);
  92
  93         dev_set_drvdata(dev, pi);
  94
  95         return devm_add_action_or_reset(dev, pvpanic_remove, pi);
  96 }
  97 EXPORT_SYMBOL_GPL(devm_pvpanic_probe);
  98
  99 static int pvpanic_init(void)
 100 {
 101         INIT_LIST_HEAD(&pvpanic_list);
 102         spin_lock_init(&pvpanic_lock);
 103
 104         atomic_notifier_chain_register(&panic_notifier_list, &pvpanic_panic_nb);
 105
 106         return 0;
 107 }
 108 module_init(pvpanic_init);
 109
 110 static void pvpanic_exit(void)
 111 {
 112         atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb);
 113
 114 }
 115 module_exit(pvpanic_exit);