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 <[email protected]>");
  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         spin_lock(&pvpanic_lock);
  38         list_for_each_entry(pi_cur, &pvpanic_list, list) {
  39                 if (event & pi_cur->capability & pi_cur->events)
  40                         iowrite8(event, pi_cur->base);
  41         }
  42         spin_unlock(&pvpanic_lock);
  43 }
  44
  45 static int
  46 pvpanic_panic_notify(struct notifier_block *nb, unsigned long code, void *unused)
  47 {
  48         unsigned int event = PVPANIC_PANICKED;
  49
  50         if (kexec_crash_loaded())
  51                 event = PVPANIC_CRASH_LOADED;
  52
  53         pvpanic_send_event(event);
  54
  55         return NOTIFY_DONE;
  56 }
  57
  58 static struct notifier_block pvpanic_panic_nb = {
  59         .notifier_call = pvpanic_panic_notify,
  60         .priority = 1, /* let this called before broken drm_fb_helper() */
  61 };
  62
  63 static void pvpanic_remove(void *param)
  64 {
  65         struct pvpanic_instance *pi_cur, *pi_next;
  66         struct pvpanic_instance *pi = param;
  67
  68         spin_lock(&pvpanic_lock);
  69         list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) {
  70                 if (pi_cur == pi) {
  71                         list_del(&pi_cur->list);
  72                         break;
  73                 }
  74         }
  75         spin_unlock(&pvpanic_lock);
  76 }
  77
  78 int devm_pvpanic_probe(struct device *dev, struct pvpanic_instance *pi)
  79 {
  80         if (!pi || !pi->base)
  81                 return -EINVAL;
  82
  83         spin_lock(&pvpanic_lock);
  84         list_add(&pi->list, &pvpanic_list);
  85         spin_unlock(&pvpanic_lock);
  86
  87         dev_set_drvdata(dev, pi);
  88
  89         return devm_add_action_or_reset(dev, pvpanic_remove, pi);
  90 }
  91 EXPORT_SYMBOL_GPL(devm_pvpanic_probe);
  92
  93 static int pvpanic_init(void)
  94 {
  95         INIT_LIST_HEAD(&pvpanic_list);
  96         spin_lock_init(&pvpanic_lock);
  97
  98         atomic_notifier_chain_register(&panic_notifier_list, &pvpanic_panic_nb);
  99
 100         return 0;
 101 }
 102 module_init(pvpanic_init);
 103
 104 static void pvpanic_exit(void)
 105 {
 106         atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb);
 107
 108 }
 109 module_exit(pvpanic_exit);