// SPDX-License-Identifier: GPL-2.0
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/*
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* Functions for saving/restoring console.
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*
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* Originally from swsusp.
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*/
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#include <linux/console.h>
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#include <linux/vt_kern.h>
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#include <linux/kbd_kern.h>
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#include <linux/vt.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include "power.h"
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#define SUSPEND_CONSOLE (MAX_NR_CONSOLES-1)
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static int orig_fgconsole, orig_kmsg;
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static DEFINE_MUTEX(vt_switch_mutex);
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struct pm_vt_switch {
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struct list_head head;
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struct device *dev;
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bool required;
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};
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static LIST_HEAD(pm_vt_switch_list);
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/**
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* pm_vt_switch_required - indicate VT switch at suspend requirements
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* @dev: device
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* @required: if true, caller needs VT switch at suspend/resume time
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*
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* The different console drivers may or may not require VT switches across
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* suspend/resume, depending on how they handle restoring video state and
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* what may be running.
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*
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* Drivers can indicate support for switchless suspend/resume, which can
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* save time and flicker, by using this routine and passing 'false' as
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* the argument. If any loaded driver needs VT switching, or the
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* no_console_suspend argument has been passed on the command line, VT
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* switches will occur.
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*/
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void pm_vt_switch_required(struct device *dev, bool required)
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{
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struct pm_vt_switch *entry, *tmp;
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mutex_lock(&vt_switch_mutex);
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list_for_each_entry(tmp, &pm_vt_switch_list, head) {
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if (tmp->dev == dev) {
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/* already registered, update requirement */
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tmp->required = required;
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goto out;
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}
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}
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entry = kmalloc(sizeof(*entry), GFP_KERNEL);
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if (!entry)
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goto out;
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entry->required = required;
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entry->dev = dev;
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list_add(&entry->head, &pm_vt_switch_list);
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out:
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mutex_unlock(&vt_switch_mutex);
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}
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EXPORT_SYMBOL(pm_vt_switch_required);
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/**
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* pm_vt_switch_unregister - stop tracking a device's VT switching needs
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* @dev: device
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*
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* Remove @dev from the vt switch list.
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*/
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void pm_vt_switch_unregister(struct device *dev)
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{
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struct pm_vt_switch *tmp;
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mutex_lock(&vt_switch_mutex);
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list_for_each_entry(tmp, &pm_vt_switch_list, head) {
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if (tmp->dev == dev) {
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list_del(&tmp->head);
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kfree(tmp);
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break;
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}
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}
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mutex_unlock(&vt_switch_mutex);
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}
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EXPORT_SYMBOL(pm_vt_switch_unregister);
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/*
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* There are three cases when a VT switch on suspend/resume are required:
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* 1) no driver has indicated a requirement one way or another, so preserve
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* the old behavior
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* 2) console suspend is disabled, we want to see debug messages across
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* suspend/resume
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* 3) any registered driver indicates it needs a VT switch
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*
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* If none of these conditions is present, meaning we have at least one driver
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* that doesn't need the switch, and none that do, we can avoid it to make
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* resume look a little prettier (and suspend too, but that's usually hidden,
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* e.g. when closing the lid on a laptop).
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*/
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static bool pm_vt_switch(void)
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{
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struct pm_vt_switch *entry;
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bool ret = true;
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mutex_lock(&vt_switch_mutex);
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if (list_empty(&pm_vt_switch_list))
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goto out;
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if (!console_suspend_enabled)
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goto out;
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list_for_each_entry(entry, &pm_vt_switch_list, head) {
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if (entry->required)
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goto out;
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}
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ret = false;
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out:
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mutex_unlock(&vt_switch_mutex);
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return ret;
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}
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void pm_prepare_console(void)
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{
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if (!pm_vt_switch())
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return;
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orig_fgconsole = vt_move_to_console(SUSPEND_CONSOLE, 1);
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if (orig_fgconsole < 0)
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return;
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orig_kmsg = vt_kmsg_redirect(SUSPEND_CONSOLE);
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return;
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}
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void pm_restore_console(void)
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{
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if (!pm_vt_switch())
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return;
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if (orig_fgconsole >= 0) {
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vt_move_to_console(orig_fgconsole, 0);
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vt_kmsg_redirect(orig_kmsg);
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}
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}
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