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// SPDX-License-Identifier: GPL-2.0+
/*
* Pvpanic Device Support
*
* Copyright (C) 2013 Fujitsu.
* Copyright (C) 2018 ZTE.
* Copyright (C) 2021 Oracle.
*/
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/gfp_types.h>
#include <linux/io.h>
#include <linux/kexec.h>
#include <linux/kstrtox.h>
#include <linux/limits.h>
#include <linux/list.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/panic_notifier.h>
#include <linux/platform_device.h>
#include <linux/reboot.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>
#include <linux/types.h>
#include <uapi/misc/pvpanic.h>
#include "pvpanic.h"
MODULE_AUTHOR("Mihai Carabas <mihai.carabas@oracle.com>");
MODULE_DESCRIPTION("pvpanic device driver");
MODULE_LICENSE("GPL");
struct pvpanic_instance {
void __iomem *base;
unsigned int capability;
unsigned int events;
struct sys_off_handler *sys_off;
struct list_head list;
};
static struct list_head pvpanic_list;
static spinlock_t pvpanic_lock;
static void
pvpanic_send_event(unsigned int event)
{
struct pvpanic_instance *pi_cur;
if (!spin_trylock(&pvpanic_lock))
return;
list_for_each_entry(pi_cur, &pvpanic_list, list) {
if (event & pi_cur->capability & pi_cur->events)
iowrite8(event, pi_cur->base);
}
spin_unlock(&pvpanic_lock);
}
static int
pvpanic_panic_notify(struct notifier_block *nb, unsigned long code, void *unused)
{
unsigned int event = PVPANIC_PANICKED;
if (kexec_crash_loaded())
event = PVPANIC_CRASH_LOADED;
pvpanic_send_event(event);
return NOTIFY_DONE;
}
/*
* Call our notifier very early on panic, deferring the
* action taken to the hypervisor.
*/
static struct notifier_block pvpanic_panic_nb = {
.notifier_call = pvpanic_panic_notify,
.priority = INT_MAX,
};
static int pvpanic_sys_off(struct sys_off_data *data)
{
pvpanic_send_event(PVPANIC_SHUTDOWN);
return NOTIFY_DONE;
}
static void pvpanic_synchronize_sys_off_handler(struct device *dev, struct pvpanic_instance *pi)
{
/* The kernel core has logic to fall back to system halt if no
* sys_off_handler is registered.
* When the pvpanic sys_off_handler is disabled via sysfs the kernel
* should use that fallback logic, so the handler needs to be unregistered.
*/
struct sys_off_handler *sys_off;
if (!(pi->events & PVPANIC_SHUTDOWN) == !pi->sys_off)
return;
if (!pi->sys_off) {
sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, SYS_OFF_PRIO_LOW,
pvpanic_sys_off, NULL);
if (IS_ERR(sys_off))
dev_warn(dev, "Could not register sys_off_handler: %pe\n", sys_off);
else
pi->sys_off = sys_off;
} else {
unregister_sys_off_handler(pi->sys_off);
pi->sys_off = NULL;
}
}
static void pvpanic_remove(void *param)
{
struct pvpanic_instance *pi_cur, *pi_next;
struct pvpanic_instance *pi = param;
spin_lock(&pvpanic_lock);
list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) {
if (pi_cur == pi) {
list_del(&pi_cur->list);
break;
}
}
spin_unlock(&pvpanic_lock);
unregister_sys_off_handler(pi->sys_off);
}
static ssize_t capability_show(struct device *dev, struct device_attribute *attr, char *buf)
{
struct pvpanic_instance *pi = dev_get_drvdata(dev);
return sysfs_emit(buf, "%x\n", pi->capability);
}
static DEVICE_ATTR_RO(capability);
static ssize_t events_show(struct device *dev, struct device_attribute *attr, char *buf)
{
struct pvpanic_instance *pi = dev_get_drvdata(dev);
return sysfs_emit(buf, "%x\n", pi->events);
}
static ssize_t events_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct pvpanic_instance *pi = dev_get_drvdata(dev);
unsigned int tmp;
int err;
err = kstrtouint(buf, 16, &tmp);
if (err)
return err;
if ((tmp & pi->capability) != tmp)
return -EINVAL;
pi->events = tmp;
pvpanic_synchronize_sys_off_handler(dev, pi);
return count;
}
static DEVICE_ATTR_RW(events);
static struct attribute *pvpanic_dev_attrs[] = {
&dev_attr_capability.attr,
&dev_attr_events.attr,
NULL
};
static const struct attribute_group pvpanic_dev_group = {
.attrs = pvpanic_dev_attrs,
};
const struct attribute_group *pvpanic_dev_groups[] = {
&pvpanic_dev_group,
NULL
};
EXPORT_SYMBOL_GPL(pvpanic_dev_groups);
int devm_pvpanic_probe(struct device *dev, void __iomem *base)
{
struct pvpanic_instance *pi;
if (!base)
return -EINVAL;
pi = devm_kmalloc(dev, sizeof(*pi), GFP_KERNEL);
if (!pi)
return -ENOMEM;
pi->base = base;
pi->capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED | PVPANIC_SHUTDOWN;
/* initlize capability by RDPT */
pi->capability &= ioread8(base);
pi->events = pi->capability;
pi->sys_off = NULL;
pvpanic_synchronize_sys_off_handler(dev, pi);
spin_lock(&pvpanic_lock);
list_add(&pi->list, &pvpanic_list);
spin_unlock(&pvpanic_lock);
dev_set_drvdata(dev, pi);
return devm_add_action_or_reset(dev, pvpanic_remove, pi);
}
EXPORT_SYMBOL_GPL(devm_pvpanic_probe);
static int pvpanic_init(void)
{
INIT_LIST_HEAD(&pvpanic_list);
spin_lock_init(&pvpanic_lock);
atomic_notifier_chain_register(&panic_notifier_list, &pvpanic_panic_nb);
return 0;
}
module_init(pvpanic_init);
static void pvpanic_exit(void)
{
atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb);
}
module_exit(pvpanic_exit);
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