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
 25MODULE_AUTHOR("Mihai Carabas <mihai.carabas@oracle.com>");
 26MODULE_DESCRIPTION("pvpanic device driver");
 27MODULE_LICENSE("GPL");
 28
 29static struct list_head pvpanic_list;
 30static spinlock_t pvpanic_lock;
 31
 32static void
 33pvpanic_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
 47static int
 48pvpanic_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 */
 64static struct notifier_block pvpanic_panic_nb = {
 65	.notifier_call = pvpanic_panic_notify,
 66	.priority = INT_MAX,
 67};
 68
 69static 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
 84int 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}
 97EXPORT_SYMBOL_GPL(devm_pvpanic_probe);
 98
 99static 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}
108module_init(pvpanic_init);
109
110static void pvpanic_exit(void)
111{
112	atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb);
113
114}
115module_exit(pvpanic_exit);