Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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/reboot.h>
23#include <linux/spinlock.h>
24#include <linux/sysfs.h>
25#include <linux/types.h>
26
27#include <uapi/misc/pvpanic.h>
28
29#include "pvpanic.h"
30
31MODULE_AUTHOR("Mihai Carabas <mihai.carabas@oracle.com>");
32MODULE_DESCRIPTION("pvpanic device driver");
33MODULE_LICENSE("GPL");
34
35struct pvpanic_instance {
36 void __iomem *base;
37 unsigned int capability;
38 unsigned int events;
39 struct sys_off_handler *sys_off;
40 struct list_head list;
41};
42
43static struct list_head pvpanic_list;
44static spinlock_t pvpanic_lock;
45
46static void
47pvpanic_send_event(unsigned int event)
48{
49 struct pvpanic_instance *pi_cur;
50
51 if (!spin_trylock(&pvpanic_lock))
52 return;
53
54 list_for_each_entry(pi_cur, &pvpanic_list, list) {
55 if (event & pi_cur->capability & pi_cur->events)
56 iowrite8(event, pi_cur->base);
57 }
58 spin_unlock(&pvpanic_lock);
59}
60
61static int
62pvpanic_panic_notify(struct notifier_block *nb, unsigned long code, void *unused)
63{
64 unsigned int event = PVPANIC_PANICKED;
65
66 if (kexec_crash_loaded())
67 event = PVPANIC_CRASH_LOADED;
68
69 pvpanic_send_event(event);
70
71 return NOTIFY_DONE;
72}
73
74/*
75 * Call our notifier very early on panic, deferring the
76 * action taken to the hypervisor.
77 */
78static struct notifier_block pvpanic_panic_nb = {
79 .notifier_call = pvpanic_panic_notify,
80 .priority = INT_MAX,
81};
82
83static int pvpanic_sys_off(struct sys_off_data *data)
84{
85 pvpanic_send_event(PVPANIC_SHUTDOWN);
86
87 return NOTIFY_DONE;
88}
89
90static void pvpanic_synchronize_sys_off_handler(struct device *dev, struct pvpanic_instance *pi)
91{
92 /* The kernel core has logic to fall back to system halt if no
93 * sys_off_handler is registered.
94 * When the pvpanic sys_off_handler is disabled via sysfs the kernel
95 * should use that fallback logic, so the handler needs to be unregistered.
96 */
97
98 struct sys_off_handler *sys_off;
99
100 if (!(pi->events & PVPANIC_SHUTDOWN) == !pi->sys_off)
101 return;
102
103 if (!pi->sys_off) {
104 sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, SYS_OFF_PRIO_LOW,
105 pvpanic_sys_off, NULL);
106 if (IS_ERR(sys_off))
107 dev_warn(dev, "Could not register sys_off_handler: %pe\n", sys_off);
108 else
109 pi->sys_off = sys_off;
110 } else {
111 unregister_sys_off_handler(pi->sys_off);
112 pi->sys_off = NULL;
113 }
114}
115
116static void pvpanic_remove(void *param)
117{
118 struct pvpanic_instance *pi_cur, *pi_next;
119 struct pvpanic_instance *pi = param;
120
121 spin_lock(&pvpanic_lock);
122 list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) {
123 if (pi_cur == pi) {
124 list_del(&pi_cur->list);
125 break;
126 }
127 }
128 spin_unlock(&pvpanic_lock);
129
130 unregister_sys_off_handler(pi->sys_off);
131}
132
133static ssize_t capability_show(struct device *dev, struct device_attribute *attr, char *buf)
134{
135 struct pvpanic_instance *pi = dev_get_drvdata(dev);
136
137 return sysfs_emit(buf, "%x\n", pi->capability);
138}
139static DEVICE_ATTR_RO(capability);
140
141static ssize_t events_show(struct device *dev, struct device_attribute *attr, char *buf)
142{
143 struct pvpanic_instance *pi = dev_get_drvdata(dev);
144
145 return sysfs_emit(buf, "%x\n", pi->events);
146}
147
148static ssize_t events_store(struct device *dev, struct device_attribute *attr,
149 const char *buf, size_t count)
150{
151 struct pvpanic_instance *pi = dev_get_drvdata(dev);
152 unsigned int tmp;
153 int err;
154
155 err = kstrtouint(buf, 16, &tmp);
156 if (err)
157 return err;
158
159 if ((tmp & pi->capability) != tmp)
160 return -EINVAL;
161
162 pi->events = tmp;
163 pvpanic_synchronize_sys_off_handler(dev, pi);
164
165 return count;
166}
167static DEVICE_ATTR_RW(events);
168
169static struct attribute *pvpanic_dev_attrs[] = {
170 &dev_attr_capability.attr,
171 &dev_attr_events.attr,
172 NULL
173};
174
175static const struct attribute_group pvpanic_dev_group = {
176 .attrs = pvpanic_dev_attrs,
177};
178
179const struct attribute_group *pvpanic_dev_groups[] = {
180 &pvpanic_dev_group,
181 NULL
182};
183EXPORT_SYMBOL_GPL(pvpanic_dev_groups);
184
185int devm_pvpanic_probe(struct device *dev, void __iomem *base)
186{
187 struct pvpanic_instance *pi;
188
189 if (!base)
190 return -EINVAL;
191
192 pi = devm_kmalloc(dev, sizeof(*pi), GFP_KERNEL);
193 if (!pi)
194 return -ENOMEM;
195
196 pi->base = base;
197 pi->capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED | PVPANIC_SHUTDOWN;
198
199 /* initlize capability by RDPT */
200 pi->capability &= ioread8(base);
201 pi->events = pi->capability;
202
203 pi->sys_off = NULL;
204 pvpanic_synchronize_sys_off_handler(dev, pi);
205
206 spin_lock(&pvpanic_lock);
207 list_add(&pi->list, &pvpanic_list);
208 spin_unlock(&pvpanic_lock);
209
210 dev_set_drvdata(dev, pi);
211
212 return devm_add_action_or_reset(dev, pvpanic_remove, pi);
213}
214EXPORT_SYMBOL_GPL(devm_pvpanic_probe);
215
216static int pvpanic_init(void)
217{
218 INIT_LIST_HEAD(&pvpanic_list);
219 spin_lock_init(&pvpanic_lock);
220
221 atomic_notifier_chain_register(&panic_notifier_list, &pvpanic_panic_nb);
222
223 return 0;
224}
225module_init(pvpanic_init);
226
227static void pvpanic_exit(void)
228{
229 atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb);
230
231}
232module_exit(pvpanic_exit);