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(lock: &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(lock: &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(lock: &pvpanic_lock);
87 list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) {
88 if (pi_cur == pi) {
89 list_del(entry: &pi_cur->list);
90 break;
91 }
92 }
93 spin_unlock(lock: &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, fmt: "%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, fmt: "%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(s: buf, base: 16, res: &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, size: 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(lock: &pvpanic_lock);
166 list_add(new: &pi->list, head: &pvpanic_list);
167 spin_unlock(lock: &pvpanic_lock);
168
169 dev_set_drvdata(dev, data: 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(list: &pvpanic_list);
178 spin_lock_init(&pvpanic_lock);
179
180 atomic_notifier_chain_register(nh: &panic_notifier_list, nb: &pvpanic_panic_nb);
181
182 return 0;
183}
184module_init(pvpanic_init);
185
186static void pvpanic_exit(void)
187{
188 atomic_notifier_chain_unregister(nh: &panic_notifier_list, nb: &pvpanic_panic_nb);
189
190}
191module_exit(pvpanic_exit);
192

source code of linux/drivers/misc/pvpanic/pvpanic.c