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);
192