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
12 static LIST_HEAD(drm_client_sysrq_dev_list);
13 static DEFINE_MUTEX(drm_client_sysrq_dev_lock);
14
15 /* emergency restore, don't bother with error reporting */
drm_client_sysrq_restore_work_fn(struct work_struct * ignored)16 static void drm_client_sysrq_restore_work_fn(struct work_struct *ignored)
17 {
18 struct drm_device *dev;
19
20 guard(mutex)(&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, true);
27 }
28 }
29
30 static DECLARE_WORK(drm_client_sysrq_restore_work, drm_client_sysrq_restore_work_fn);
31
drm_client_sysrq_restore_handler(u8 ignored)32 static void drm_client_sysrq_restore_handler(u8 ignored)
33 {
34 schedule_work(&drm_client_sysrq_restore_work);
35 }
36
37 static 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
drm_client_sysrq_register(struct drm_device * dev)43 void drm_client_sysrq_register(struct drm_device *dev)
44 {
45 guard(mutex)(&drm_client_sysrq_dev_lock);
46
47 if (list_empty(&drm_client_sysrq_dev_list))
48 register_sysrq_key('v', &drm_client_sysrq_restore_op);
49
50 list_add(&dev->client_sysrq_list, &drm_client_sysrq_dev_list);
51 }
52
drm_client_sysrq_unregister(struct drm_device * dev)53 void drm_client_sysrq_unregister(struct drm_device *dev)
54 {
55 guard(mutex)(&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(&dev->client_sysrq_list);
60
61 /* no devices left; unregister key */
62 if (list_empty(&drm_client_sysrq_dev_list))
63 unregister_sysrq_key('v', &drm_client_sysrq_restore_op);
64 }
65 #endif
66