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1// SPDX-License-Identifier: GPL-2.0+2/*3 * Pvpanic Device Support4 *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 void47pvpanic_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 int62pvpanic_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 the76 * 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 no93 * sys_off_handler is registered.94 * When the pvpanic sys_off_handler is disabled via sysfs the kernel95 * 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 else109 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 NULL173};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 NULL182};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);233