pvpanic.c revision 7939831eacd81fccbd7a956b30c7bb3abb9079db 
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	acpi_status status;
96	u64 ret;
97
98	status = acpi_evaluate_integer(device->handle, "_STA", NULL,
99				       &ret);
100
101	if (ACPI_FAILURE(status) || (ret & 0x0B) != 0x0B)
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);
125