projects/linux·blob v3.13 · refs

150 lines · 3.4 KiB

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