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         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,
  47                      void *unused)
  48 {
  49         unsigned int event = PVPANIC_PANICKED;
  50
  51         if (kexec_crash_loaded())
  52                 event = PVPANIC_CRASH_LOADED;
  53
  54         pvpanic_send_event(event);
  55
  56         return NOTIFY_DONE;
  57 }
  58
  59 static struct notifier_block pvpanic_panic_nb = {
  60         .notifier_call = pvpanic_panic_notify,
  61         .priority = 1, /* let this called before broken drm_fb_helper */
  62 };
  63
  64 int pvpanic_probe(struct pvpanic_instance *pi)
  65 {
  66         if (!pi || !pi->base)
  67                 return -EINVAL;
  68
  69         spin_lock(&pvpanic_lock);
  70         list_add(&pi->list, &pvpanic_list);
  71         spin_unlock(&pvpanic_lock);
  72
  73         return 0;
  74 }
  75 EXPORT_SYMBOL_GPL(pvpanic_probe);
  76
  77 void pvpanic_remove(struct pvpanic_instance *pi)
  78 {
  79         struct pvpanic_instance *pi_cur, *pi_next;
  80
  81         if (!pi)
  82                 return;
  83
  84         spin_lock(&pvpanic_lock);
  85         list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) {
  86                 if (pi_cur == pi) {
  87                         list_del(&pi_cur->list);
  88                         break;
  89                 }
  90         }
  91         spin_unlock(&pvpanic_lock);
  92 }
  93 EXPORT_SYMBOL_GPL(pvpanic_remove);
  94
  95 static int pvpanic_init(void)
  96 {
  97         INIT_LIST_HEAD(&pvpanic_list);
  98         spin_lock_init(&pvpanic_lock);
  99
 100         atomic_notifier_chain_register(&panic_notifier_list,
 101                                        &pvpanic_panic_nb);
 102
 103         return 0;
 104 }
 105
 106 static void pvpanic_exit(void)
 107 {
 108         atomic_notifier_chain_unregister(&panic_notifier_list,
 109                                          &pvpanic_panic_nb);
 110
 111 }
 112
 113 module_init(pvpanic_init);
 114 module_exit(pvpanic_exit);