console.c
3.5 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
// SPDX-License-Identifier: GPL-2.0
/*
* Functions for saving/restoring console.
*
* Originally from swsusp.
*/
#include <linux/console.h>
#include <linux/vt_kern.h>
#include <linux/kbd_kern.h>
#include <linux/vt.h>
#include <linux/module.h>
#include <linux/slab.h>
#include "power.h"
#define SUSPEND_CONSOLE (MAX_NR_CONSOLES-1)
static int orig_fgconsole, orig_kmsg;
static DEFINE_MUTEX(vt_switch_mutex);
struct pm_vt_switch {
struct list_head head;
struct device *dev;
bool required;
};
static LIST_HEAD(pm_vt_switch_list);
/**
* pm_vt_switch_required - indicate VT switch at suspend requirements
* @dev: device
* @required: if true, caller needs VT switch at suspend/resume time
*
* The different console drivers may or may not require VT switches across
* suspend/resume, depending on how they handle restoring video state and
* what may be running.
*
* Drivers can indicate support for switchless suspend/resume, which can
* save time and flicker, by using this routine and passing 'false' as
* the argument. If any loaded driver needs VT switching, or the
* no_console_suspend argument has been passed on the command line, VT
* switches will occur.
*/
void pm_vt_switch_required(struct device *dev, bool required)
{
struct pm_vt_switch *entry, *tmp;
mutex_lock(&vt_switch_mutex);
list_for_each_entry(tmp, &pm_vt_switch_list, head) {
if (tmp->dev == dev) {
/* already registered, update requirement */
tmp->required = required;
goto out;
}
}
entry = kmalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
goto out;
entry->required = required;
entry->dev = dev;
list_add(&entry->head, &pm_vt_switch_list);
out:
mutex_unlock(&vt_switch_mutex);
}
EXPORT_SYMBOL(pm_vt_switch_required);
/**
* pm_vt_switch_unregister - stop tracking a device's VT switching needs
* @dev: device
*
* Remove @dev from the vt switch list.
*/
void pm_vt_switch_unregister(struct device *dev)
{
struct pm_vt_switch *tmp;
mutex_lock(&vt_switch_mutex);
list_for_each_entry(tmp, &pm_vt_switch_list, head) {
if (tmp->dev == dev) {
list_del(&tmp->head);
kfree(tmp);
break;
}
}
mutex_unlock(&vt_switch_mutex);
}
EXPORT_SYMBOL(pm_vt_switch_unregister);
/*
* There are three cases when a VT switch on suspend/resume are required:
* 1) no driver has indicated a requirement one way or another, so preserve
* the old behavior
* 2) console suspend is disabled, we want to see debug messages across
* suspend/resume
* 3) any registered driver indicates it needs a VT switch
*
* If none of these conditions is present, meaning we have at least one driver
* that doesn't need the switch, and none that do, we can avoid it to make
* resume look a little prettier (and suspend too, but that's usually hidden,
* e.g. when closing the lid on a laptop).
*/
static bool pm_vt_switch(void)
{
struct pm_vt_switch *entry;
bool ret = true;
mutex_lock(&vt_switch_mutex);
if (list_empty(&pm_vt_switch_list))
goto out;
if (!console_suspend_enabled)
goto out;
list_for_each_entry(entry, &pm_vt_switch_list, head) {
if (entry->required)
goto out;
}
ret = false;
out:
mutex_unlock(&vt_switch_mutex);
return ret;
}
void pm_prepare_console(void)
{
if (!pm_vt_switch())
return;
orig_fgconsole = vt_move_to_console(SUSPEND_CONSOLE, 1);
if (orig_fgconsole < 0)
return;
orig_kmsg = vt_kmsg_redirect(SUSPEND_CONSOLE);
return;
}
void pm_restore_console(void)
{
if (!pm_vt_switch())
return;
if (orig_fgconsole >= 0) {
vt_move_to_console(orig_fgconsole, 0);
vt_kmsg_redirect(orig_kmsg);
}
}