1// SPDX-License-Identifier: GPL-2.0 or MIT
2
3#include <linux/sysrq.h>
4
5#include <drm/drm_client_event.h>
6#include <drm/drm_device.h>
7#include <drm/drm_print.h>
8
9#include "drm_internal.h"
10
11#ifdef CONFIG_MAGIC_SYSRQ
12static LIST_HEAD(drm_client_sysrq_dev_list);
13static DEFINE_MUTEX(drm_client_sysrq_dev_lock);
14
15/* emergency restore, don't bother with error reporting */
16static void drm_client_sysrq_restore_work_fn(struct work_struct *ignored)
17{
18 struct drm_device *dev;
19
20 guard(mutex)(T: &drm_client_sysrq_dev_lock);
21
22 list_for_each_entry(dev, &drm_client_sysrq_dev_list, client_sysrq_list) {
23 if (dev->switch_power_state == DRM_SWITCH_POWER_OFF)
24 continue;
25
26 drm_client_dev_restore(dev, force: true);
27 }
28}
29
30static DECLARE_WORK(drm_client_sysrq_restore_work, drm_client_sysrq_restore_work_fn);
31
32static void drm_client_sysrq_restore_handler(u8 ignored)
33{
34 schedule_work(work: &drm_client_sysrq_restore_work);
35}
36
37static const struct sysrq_key_op drm_client_sysrq_restore_op = {
38 .handler = drm_client_sysrq_restore_handler,
39 .help_msg = "force-fb(v)",
40 .action_msg = "Restore framebuffer console",
41};
42
43void drm_client_sysrq_register(struct drm_device *dev)
44{
45 guard(mutex)(T: &drm_client_sysrq_dev_lock);
46
47 if (list_empty(head: &drm_client_sysrq_dev_list))
48 register_sysrq_key(key: 'v', op: &drm_client_sysrq_restore_op);
49
50 list_add(new: &dev->client_sysrq_list, head: &drm_client_sysrq_dev_list);
51}
52
53void drm_client_sysrq_unregister(struct drm_device *dev)
54{
55 guard(mutex)(T: &drm_client_sysrq_dev_lock);
56
57 /* remove device from global restore list */
58 if (!drm_WARN_ON(dev, list_empty(&dev->client_sysrq_list)))
59 list_del(entry: &dev->client_sysrq_list);
60
61 /* no devices left; unregister key */
62 if (list_empty(head: &drm_client_sysrq_dev_list))
63 unregister_sysrq_key(key: 'v', op: &drm_client_sysrq_restore_op);
64}
65#endif
66

source code of linux/drivers/gpu/drm/drm_client_sysrq.c