rt2x00usb: fix anchor initialization
[linux/fpc-iii.git] / kernel / power / console.c
blob0e781798b0b364594696f893a79c2659f8c6b7d2
1 /*
2 * Functions for saving/restoring console.
4 * Originally from swsusp.
5 */
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 <linux/slab.h>
13 #include "power.h"
15 #define SUSPEND_CONSOLE (MAX_NR_CONSOLES-1)
17 static int orig_fgconsole, orig_kmsg;
19 static DEFINE_MUTEX(vt_switch_mutex);
21 struct pm_vt_switch {
22 struct list_head head;
23 struct device *dev;
24 bool required;
27 static LIST_HEAD(pm_vt_switch_list);
30 /**
31 * pm_vt_switch_required - indicate VT switch at suspend requirements
32 * @dev: device
33 * @required: if true, caller needs VT switch at suspend/resume time
35 * The different console drivers may or may not require VT switches across
36 * suspend/resume, depending on how they handle restoring video state and
37 * what may be running.
39 * Drivers can indicate support for switchless suspend/resume, which can
40 * save time and flicker, by using this routine and passing 'false' as
41 * the argument. If any loaded driver needs VT switching, or the
42 * no_console_suspend argument has been passed on the command line, VT
43 * switches will occur.
45 void pm_vt_switch_required(struct device *dev, bool required)
47 struct pm_vt_switch *entry, *tmp;
49 mutex_lock(&vt_switch_mutex);
50 list_for_each_entry(tmp, &pm_vt_switch_list, head) {
51 if (tmp->dev == dev) {
52 /* already registered, update requirement */
53 tmp->required = required;
54 goto out;
58 entry = kmalloc(sizeof(*entry), GFP_KERNEL);
59 if (!entry)
60 goto out;
62 entry->required = required;
63 entry->dev = dev;
65 list_add(&entry->head, &pm_vt_switch_list);
66 out:
67 mutex_unlock(&vt_switch_mutex);
69 EXPORT_SYMBOL(pm_vt_switch_required);
71 /**
72 * pm_vt_switch_unregister - stop tracking a device's VT switching needs
73 * @dev: device
75 * Remove @dev from the vt switch list.
77 void pm_vt_switch_unregister(struct device *dev)
79 struct pm_vt_switch *tmp;
81 mutex_lock(&vt_switch_mutex);
82 list_for_each_entry(tmp, &pm_vt_switch_list, head) {
83 if (tmp->dev == dev) {
84 list_del(&tmp->head);
85 kfree(tmp);
86 break;
89 mutex_unlock(&vt_switch_mutex);
91 EXPORT_SYMBOL(pm_vt_switch_unregister);
94 * There are three cases when a VT switch on suspend/resume are required:
95 * 1) no driver has indicated a requirement one way or another, so preserve
96 * the old behavior
97 * 2) console suspend is disabled, we want to see debug messages across
98 * suspend/resume
99 * 3) any registered driver indicates it needs a VT switch
101 * If none of these conditions is present, meaning we have at least one driver
102 * that doesn't need the switch, and none that do, we can avoid it to make
103 * resume look a little prettier (and suspend too, but that's usually hidden,
104 * e.g. when closing the lid on a laptop).
106 static bool pm_vt_switch(void)
108 struct pm_vt_switch *entry;
109 bool ret = true;
111 mutex_lock(&vt_switch_mutex);
112 if (list_empty(&pm_vt_switch_list))
113 goto out;
115 if (!console_suspend_enabled)
116 goto out;
118 list_for_each_entry(entry, &pm_vt_switch_list, head) {
119 if (entry->required)
120 goto out;
123 ret = false;
124 out:
125 mutex_unlock(&vt_switch_mutex);
126 return ret;
129 void pm_prepare_console(void)
131 if (!pm_vt_switch())
132 return;
134 orig_fgconsole = vt_move_to_console(SUSPEND_CONSOLE, 1);
135 if (orig_fgconsole < 0)
136 return;
138 orig_kmsg = vt_kmsg_redirect(SUSPEND_CONSOLE);
139 return;
142 void pm_restore_console(void)
144 if (!pm_vt_switch())
145 return;
147 if (orig_fgconsole >= 0) {
148 vt_move_to_console(orig_fgconsole, 0);
149 vt_kmsg_redirect(orig_kmsg);