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/device.h>
 11#include <linux/errno.h>
 12#include <linux/gfp_types.h>
 13#include <linux/io.h>
 14#include <linux/kexec.h>
 15#include <linux/kstrtox.h>
 16#include <linux/limits.h>
 17#include <linux/list.h>
 18#include <linux/mod_devicetable.h>
 19#include <linux/module.h>
 20#include <linux/panic_notifier.h>
 21#include <linux/platform_device.h>
 22#include <linux/spinlock.h>
 23#include <linux/sysfs.h>
 24#include <linux/types.h>
 25
 26#include <uapi/misc/pvpanic.h>
 27
 28#include "pvpanic.h"
 29
 30MODULE_AUTHOR("Mihai Carabas <mihai.carabas@oracle.com>");
 31MODULE_DESCRIPTION("pvpanic device driver");
 32MODULE_LICENSE("GPL");
 33
 34struct pvpanic_instance {
 35	void __iomem *base;
 36	unsigned int capability;
 37	unsigned int events;
 38	struct list_head list;
 39};
 40
 41static struct list_head pvpanic_list;
 42static spinlock_t pvpanic_lock;
 43
 44static void
 45pvpanic_send_event(unsigned int event)
 46{
 47	struct pvpanic_instance *pi_cur;
 48
 49	if (!spin_trylock(&pvpanic_lock))
 50		return;
 51
 52	list_for_each_entry(pi_cur, &pvpanic_list, list) {
 53		if (event & pi_cur->capability & pi_cur->events)
 54			iowrite8(event, pi_cur->base);
 55	}
 56	spin_unlock(&pvpanic_lock);
 57}
 58
 59static int
 60pvpanic_panic_notify(struct notifier_block *nb, unsigned long code, void *unused)
 61{
 62	unsigned int event = PVPANIC_PANICKED;
 63
 64	if (kexec_crash_loaded())
 65		event = PVPANIC_CRASH_LOADED;
 66
 67	pvpanic_send_event(event);
 68
 69	return NOTIFY_DONE;
 70}
 71
 72/*
 73 * Call our notifier very early on panic, deferring the
 74 * action taken to the hypervisor.
 75 */
 76static struct notifier_block pvpanic_panic_nb = {
 77	.notifier_call = pvpanic_panic_notify,
 78	.priority = INT_MAX,
 79};
 80
 81static void pvpanic_remove(void *param)
 82{
 83	struct pvpanic_instance *pi_cur, *pi_next;
 84	struct pvpanic_instance *pi = param;
 85
 86	spin_lock(&pvpanic_lock);
 87	list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) {
 88		if (pi_cur == pi) {
 89			list_del(&pi_cur->list);
 90			break;
 91		}
 92	}
 93	spin_unlock(&pvpanic_lock);
 94}
 95
 96static ssize_t capability_show(struct device *dev, struct device_attribute *attr, char *buf)
 97{
 98	struct pvpanic_instance *pi = dev_get_drvdata(dev);
 99
100	return sysfs_emit(buf, "%x\n", pi->capability);
101}
102static DEVICE_ATTR_RO(capability);
103
104static ssize_t events_show(struct device *dev, struct device_attribute *attr, char *buf)
105{
106	struct pvpanic_instance *pi = dev_get_drvdata(dev);
107
108	return sysfs_emit(buf, "%x\n", pi->events);
109}
110
111static ssize_t events_store(struct device *dev, struct device_attribute *attr,
112			    const char *buf, size_t count)
113{
114	struct pvpanic_instance *pi = dev_get_drvdata(dev);
115	unsigned int tmp;
116	int err;
117
118	err = kstrtouint(buf, 16, &tmp);
119	if (err)
120		return err;
121
122	if ((tmp & pi->capability) != tmp)
123		return -EINVAL;
124
125	pi->events = tmp;
126
127	return count;
128}
129static DEVICE_ATTR_RW(events);
130
131static struct attribute *pvpanic_dev_attrs[] = {
132	&dev_attr_capability.attr,
133	&dev_attr_events.attr,
134	NULL
135};
136
137static const struct attribute_group pvpanic_dev_group = {
138	.attrs = pvpanic_dev_attrs,
139};
140
141const struct attribute_group *pvpanic_dev_groups[] = {
142	&pvpanic_dev_group,
143	NULL
144};
145EXPORT_SYMBOL_GPL(pvpanic_dev_groups);
146
147int devm_pvpanic_probe(struct device *dev, void __iomem *base)
148{
149	struct pvpanic_instance *pi;
150
151	if (!base)
152		return -EINVAL;
153
154	pi = devm_kmalloc(dev, sizeof(*pi), GFP_KERNEL);
155	if (!pi)
156		return -ENOMEM;
157
158	pi->base = base;
159	pi->capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED;
160
161	/* initlize capability by RDPT */
162	pi->capability &= ioread8(base);
163	pi->events = pi->capability;
164
165	spin_lock(&pvpanic_lock);
166	list_add(&pi->list, &pvpanic_list);
167	spin_unlock(&pvpanic_lock);
168
169	dev_set_drvdata(dev, pi);
170
171	return devm_add_action_or_reset(dev, pvpanic_remove, pi);
172}
173EXPORT_SYMBOL_GPL(devm_pvpanic_probe);
174
175static int pvpanic_init(void)
176{
177	INIT_LIST_HEAD(&pvpanic_list);
178	spin_lock_init(&pvpanic_lock);
179
180	atomic_notifier_chain_register(&panic_notifier_list, &pvpanic_panic_nb);
181
182	return 0;
183}
184module_init(pvpanic_init);
185
186static void pvpanic_exit(void)
187{
188	atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb);
189
190}
191module_exit(pvpanic_exit);