1/*
  2 *  pvpanic.c - pvpanic Device Support
  3 *
  4 *  Copyright (C) 2013 Fujitsu.
  5 *
  6 *  This program is free software; you can redistribute it and/or modify
  7 *  it under the terms of the GNU General Public License as published by
  8 *  the Free Software Foundation; either version 2 of the License, or
  9 *  (at your option) any later version.
 10 *
 11 *  This program is distributed in the hope that it will be useful,
 12 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 13 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14 *  GNU General Public License for more details.
 15 *
 16 *  You should have received a copy of the GNU General Public License
 17 *  along with this program; if not, write to the Free Software
 18 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 19 */
 20
 21#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 22
 23#include <linux/kernel.h>
 24#include <linux/module.h>
 25#include <linux/init.h>
 26#include <linux/types.h>
 27#include <linux/acpi.h>
 28
 29MODULE_AUTHOR("Hu Tao <hutao@cn.fujitsu.com>");
 30MODULE_DESCRIPTION("pvpanic device driver");
 31MODULE_LICENSE("GPL");
 32
 33static int pvpanic_add(struct acpi_device *device);
 34static int pvpanic_remove(struct acpi_device *device);
 35
 36static const struct acpi_device_id pvpanic_device_ids[] = {
 37	{ "QEMU0001", 0 },
 38	{ "", 0 },
 39};
 40MODULE_DEVICE_TABLE(acpi, pvpanic_device_ids);
 41
 42#define PVPANIC_PANICKED	(1 << 0)
 43
 44static u16 port;
 45
 46static struct acpi_driver pvpanic_driver = {
 47	.name =		"pvpanic",
 48	.class =	"QEMU",
 49	.ids =		pvpanic_device_ids,
 50	.ops =		{
 51				.add =		pvpanic_add,
 52				.remove =	pvpanic_remove,
 53			},
 54	.owner =	THIS_MODULE,
 55};
 56
 57static void
 58pvpanic_send_event(unsigned int event)
 59{
 60	outb(event, port);
 61}
 62
 63static int
 64pvpanic_panic_notify(struct notifier_block *nb, unsigned long code,
 65		     void *unused)
 66{
 67	pvpanic_send_event(PVPANIC_PANICKED);
 68	return NOTIFY_DONE;
 69}
 70
 71static struct notifier_block pvpanic_panic_nb = {
 72	.notifier_call = pvpanic_panic_notify,
 73	.priority = 1, /* let this called before broken drm_fb_helper */
 74};
 75
 76
 77static acpi_status
 78pvpanic_walk_resources(struct acpi_resource *res, void *context)
 79{
 80	switch (res->type) {
 81	case ACPI_RESOURCE_TYPE_END_TAG:
 82		return AE_OK;
 83
 84	case ACPI_RESOURCE_TYPE_IO:
 85		port = res->data.io.minimum;
 86		return AE_OK;
 87
 88	default:
 89		return AE_ERROR;
 90	}
 91}
 92
 93static int pvpanic_add(struct acpi_device *device)
 94{
 95	int ret;
 96
 97	ret = acpi_bus_get_status(device);
 98	if (ret < 0)
 99		return ret;
100
101	if (!device->status.enabled || !device->status.functional)
102		return -ENODEV;
103
104	acpi_walk_resources(device->handle, METHOD_NAME__CRS,
105			    pvpanic_walk_resources, NULL);
106
107	if (!port)
108		return -ENODEV;
109
110	atomic_notifier_chain_register(&panic_notifier_list,
111				       &pvpanic_panic_nb);
112
113	return 0;
114}
115
116static int pvpanic_remove(struct acpi_device *device)
117{
118
119	atomic_notifier_chain_unregister(&panic_notifier_list,
120					 &pvpanic_panic_nb);
121	return 0;
122}
123
124module_acpi_driver(pvpanic_driver);