[linux-2.6-block.git] / drivers / misc / pvpanic / pvpanic.c

// 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);
Commit	Line	Data
6861d27c MC	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
c1426d39	10	#include <linux/device.h>
7037f714 AS	11	#include <linux/errno.h>
7037f714 AS	12	#include <linux/gfp_types.h>
6861d27c	13	#include <linux/io.h>
6861d27c	14	#include <linux/kexec.h>
7037f714 AS	15	#include <linux/kstrtox.h>
	16	#include <linux/limits.h>
	17	#include <linux/list.h>
6861d27c MC	18	#include <linux/mod_devicetable.h>
6861d27c MC	19	#include <linux/module.h>
f39650de	20	#include <linux/panic_notifier.h>
7037f714	21	#include <linux/platform_device.h>
7b51b137	22	#include <linux/reboot.h>
7037f714 AS	23	#include <linux/spinlock.h>
7037f714 AS	24	#include <linux/sysfs.h>
6861d27c MC	25	#include <linux/types.h>
	26
	27	#include <uapi/misc/pvpanic.h>
	28
	29	#include "pvpanic.h"
	30
	31	MODULE_AUTHOR("Mihai Carabas <mihai.carabas@oracle.com>");
84b0f12a	32	MODULE_DESCRIPTION("pvpanic device driver");
6861d27c MC	33	MODULE_LICENSE("GPL");
6861d27c MC	34
c1426d39 TW	35	struct pvpanic_instance {
	36	void __iomem *base;
	37	unsigned int capability;
	38	unsigned int events;
7b51b137	39	struct sys_off_handler *sys_off;
c1426d39 TW	40	struct list_head list;
	41	};
	42
391e2415 Y	43	static struct list_head pvpanic_list;
391e2415 Y	44	static spinlock_t pvpanic_lock;
6861d27c MC	45
	46	static void
	47	pvpanic_send_event(unsigned int event)
	48	{
b3c0f877 MC	49	struct pvpanic_instance *pi_cur;
b3c0f877 MC	50
e918c102 GP	51	if (!spin_trylock(&pvpanic_lock))
	52	return;
	53
b3c0f877 MC	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);
6861d27c MC	59	}
	60
	61	static int
84b0f12a	62	pvpanic_panic_notify(struct notifier_block nb, unsigned long code, void unused)
6861d27c MC	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
e918c102 GP	74	/*
	75	* Call our notifier very early on panic, deferring the
	76	* action taken to the hypervisor.
	77	*/
6861d27c MC	78	static struct notifier_block pvpanic_panic_nb = {
6861d27c MC	79	.notifier_call = pvpanic_panic_notify,
e918c102	80	.priority = INT_MAX,
6861d27c MC	81	};
6861d27c MC	82
7b51b137 TW	83	static int pvpanic_sys_off(struct sys_off_data *data)
	84	{
	85	pvpanic_send_event(PVPANIC_SHUTDOWN);
	86
	87	return NOTIFY_DONE;
	88	}
	89
	90	static 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
394febc9	116	static void pvpanic_remove(void *param)
6861d27c	117	{
b3c0f877	118	struct pvpanic_instance pi_cur, pi_next;
394febc9	119	struct pvpanic_instance *pi = param;
b3c0f877 MC	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);
7b51b137 TW	129
7b51b137 TW	130	unregister_sys_off_handler(pi->sys_off);
6861d27c	131	}
394febc9	132
c1426d39 TW	133	static 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	}
	139	static DEVICE_ATTR_RO(capability);
	140
	141	static 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
	148	static 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;
7b51b137	163	pvpanic_synchronize_sys_off_handler(dev, pi);
c1426d39 TW	164
	165	return count;
	166	}
	167	static DEVICE_ATTR_RW(events);
	168
	169	static struct attribute *pvpanic_dev_attrs[] = {
	170	&dev_attr_capability.attr,
	171	&dev_attr_events.attr,
	172	NULL
	173	};
	174
	175	static const struct attribute_group pvpanic_dev_group = {
	176	.attrs = pvpanic_dev_attrs,
	177	};
	178
	179	const struct attribute_group *pvpanic_dev_groups[] = {
	180	&pvpanic_dev_group,
	181	NULL
	182	};
	183	EXPORT_SYMBOL_GPL(pvpanic_dev_groups);
	184
	185	int devm_pvpanic_probe(struct device dev, void __iomem base)
394febc9	186	{
c1426d39 TW	187	struct pvpanic_instance *pi;
	188
	189	if (!base)
394febc9 CJ	190	return -EINVAL;
394febc9 CJ	191
c1426d39 TW	192	pi = devm_kmalloc(dev, sizeof(*pi), GFP_KERNEL);
	193	if (!pi)
	194	return -ENOMEM;
	195
	196	pi->base = base;
7b51b137	197	pi->capability = PVPANIC_PANICKED \| PVPANIC_CRASH_LOADED \| PVPANIC_SHUTDOWN;
c1426d39 TW	198
	199	/* initlize capability by RDPT */
	200	pi->capability &= ioread8(base);
	201	pi->events = pi->capability;
	202
7b51b137 TW	203	pi->sys_off = NULL;
	204	pvpanic_synchronize_sys_off_handler(dev, pi);
	205
394febc9 CJ	206	spin_lock(&pvpanic_lock);
	207	list_add(&pi->list, &pvpanic_list);
	208	spin_unlock(&pvpanic_lock);
	209
a99009bc MC	210	dev_set_drvdata(dev, pi);
a99009bc MC	211
394febc9 CJ	212	return devm_add_action_or_reset(dev, pvpanic_remove, pi);
	213	}
	214	EXPORT_SYMBOL_GPL(devm_pvpanic_probe);
6861d27c	215
b3c0f877	216	static int pvpanic_init(void)
6861d27c	217	{
b3c0f877 MC	218	INIT_LIST_HEAD(&pvpanic_list);
	219	spin_lock_init(&pvpanic_lock);
	220
84b0f12a	221	atomic_notifier_chain_register(&panic_notifier_list, &pvpanic_panic_nb);
b3c0f877 MC	222
b3c0f877 MC	223	return 0;
6861d27c	224	}
33a43041	225	module_init(pvpanic_init);
b3c0f877 MC	226
	227	static void pvpanic_exit(void)
	228	{
84b0f12a	229	atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb);
b3c0f877 MC	230
b3c0f877 MC	231	}
b3c0f877	232	module_exit(pvpanic_exit);