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// 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);
}
}
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