diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-09-05 11:59:05 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-09-05 11:59:05 -0700 |
| commit | 9f0346dcbea363787186c94ef94dd01aaa215afa (patch) | |
| tree | b81c168f4d0dbe4c7f4750f4598d48a6deb72094 /Documentation/input/notifier.rst | |
| download | linux-stable-9f0346dcbea363787186c94ef94dd01aaa215afa.tar.gz linux-stable-9f0346dcbea363787186c94ef94dd01aaa215afa.zip | |
Merge tag 'driver-core-7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-coregrafted
Pull driver core fixes from Danilo Krummrich:
- Fix kernfs listxattr() not returning security xattr names (e.g.
SELinux labels) when the kernfs node has no allocated kernfs_iattrs
- Fix silent truncation of IRQ vector indices in the Rust PCI
abstractions
- Don't select OF from DRIVER_PE_KUNIT_TEST; skip the test when OF is
disabled instead of silently enabling extra kernel functionality
- Russ Weight is retiring from kernel development; update the Firmware
Loader sysfs contact to the driver-core mailing list, add a CREDITS
entry for Firmware Upload, and update MAINTAINERS accordingly
* tag 'driver-core-7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core:
MAINTAINERS: Remove Russ Weight from Firmware Loader
CREDITS: Add CREDITS entry for Firmware Upload
firmware_loader: Change contact for sysfs nodes
rust: pci: reject IRQ vector indices that do not fit in u32
kernfs: preserve security xattrs without allocating iattrs
drivers: base: test: DRIVER_PE_KUNIT_TEST should not select OF
Diffstat (limited to 'Documentation/input/notifier.rst')
| -rw-r--r-- | Documentation/input/notifier.rst | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/Documentation/input/notifier.rst b/Documentation/input/notifier.rst new file mode 100644 index 000000000..824379399 --- /dev/null +++ b/Documentation/input/notifier.rst @@ -0,0 +1,55 @@ +================= +Keyboard notifier +================= + +One can use register_keyboard_notifier to get called back on keyboard +events (see kbd_keycode() function for details). The passed structure is +keyboard_notifier_param (see <linux/keyboard.h>): + +- 'vc' always provide the VC for which the keyboard event applies; +- 'down' is 1 for a key press event, 0 for a key release; +- 'shift' is the current modifier state, mask bit indexes are KG_*; +- 'ledstate' is the current LED state; +- 'value' depends on the type of event. + +- KBD_KEYCODE events are always sent before other events, value is the keycode. +- KBD_UNBOUND_KEYCODE events are sent if the keycode is not bound to a keysym. + value is the keycode. +- KBD_UNICODE events are sent if the keycode -> keysym translation produced a + unicode character. value is the unicode value. +- KBD_KEYSYM events are sent if the keycode -> keysym translation produced a + non-unicode character. value is the keysym. +- KBD_POST_KEYSYM events are sent after the treatment of non-unicode keysyms. + That permits one to inspect the resulting LEDs for instance. + +For each kind of event but the last, the callback may return NOTIFY_STOP in +order to "eat" the event: the notify loop is stopped and the keyboard event is +dropped. + +In a rough C snippet, we have:: + + kbd_keycode(keycode) { + ... + params.value = keycode; + if (notifier_call_chain(KBD_KEYCODE,¶ms) == NOTIFY_STOP) + || !bound) { + notifier_call_chain(KBD_UNBOUND_KEYCODE,¶ms); + return; + } + + if (unicode) { + param.value = unicode; + if (notifier_call_chain(KBD_UNICODE,¶ms) == NOTIFY_STOP) + return; + emit unicode; + return; + } + + params.value = keysym; + if (notifier_call_chain(KBD_KEYSYM,¶ms) == NOTIFY_STOP) + return; + apply keysym; + notifier_call_chain(KBD_POST_KEYSYM,¶ms); + } + +.. note:: This notifier is usually called from interrupt context. |
