[PATCHv4] INPUT: Route keyboard LEDs through the generic LEDs layer.

Samuel Thibault
2014-12-10T01:02:24Z

This permits to reassign keyboard LEDs to something else than keyboard "leds"
state, by adding keyboard led and modifier triggers connected to a series
of VT input LEDs, themselves connected to VT input triggers, which
per-input device LEDs use by default. Userland can thus easily change the LED
behavior of (a priori) all input devices, or of particular input devices.

This also permits to fix #7063 from userland by using a modifier to implement
proper CapsLock behavior and have the keyboard caps lock led show that modifier
state.

[ebroder@mokafive.com: Rebased to 3.2-rc1 or so, cleaned up some includes, and fixed some constants]
[blogic@openwrt.org: CONFIG_INPUT_LEDS stubs should be static inline]
[akpm@linux-foundation.org: remove unneeded `extern', fix comment layout]
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Evan Broder <evan@ebroder.net>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Tested-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Changed in this version:
- Use kcalloc instead of kzalloc
- to avoid any mutex order violation, defer LED update into a work callback.

This has been in mm for some months now.

--- a/Documentation/leds/leds-class.txt
+++ b/Documentation/leds/leds-class.txt
@@ -2,9 +2,6 @@
LED handling under Linux
========================

-If you're reading this and thinking about keyboard leds, these are
-handled by the input subsystem and the led class is *not* needed.
-
In its simplest form, the LED class just allows control of LEDs from
userspace. LEDs appear in /sys/class/leds/. The maximum brightness of the
LED is defined in max_brightness file. The brightness file will set the brightness
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -711,6 +711,9 @@ static void input_disconnect_device(stru
handle->open = 0;

spin_unlock_irq(&dev->event_lock);
+
+ if (is_event_supported(EV_LED, dev->evbit, EV_MAX))
+ input_led_disconnect(dev);
}

/**
@@ -2137,6 +2140,9 @@ int input_register_device(struct input_d

list_add_tail(&dev->node, &input_dev_list);

+ if (is_event_supported(EV_LED, dev->evbit, EV_MAX))
+ input_led_connect(dev);
+
list_for_each_entry(handler, &input_handler_list, node)
input_attach_handler(dev, handler);

@@ -2422,6 +2428,8 @@ static int __init input_init(void)
goto fail2;
}

+ input_led_init();
+
return 0;

fail2: input_proc_exit();
@@ -2431,6 +2439,7 @@ static int __init input_init(void)

static void __exit input_exit(void)
{
+ input_led_exit();
input_proc_exit();
unregister_chrdev_region(MKDEV(INPUT_MAJOR, 0),
INPUT_MAX_CHAR_DEVICES);
--- a/drivers/input/Kconfig
+++ b/drivers/input/Kconfig
@@ -178,6 +178,15 @@ comment "Input Device Drivers"

source "drivers/input/keyboard/Kconfig"

+config INPUT_LEDS
+ bool "LED Support"
+ depends on LEDS_CLASS = INPUT || LEDS_CLASS = y
+ select LEDS_TRIGGERS
+ default y
+ help
+ This option enables support for LEDs on keyboards managed
+ by the input layer.
+
source "drivers/input/mouse/Kconfig"

source "drivers/input/joystick/Kconfig"
--- a/drivers/input/Makefile
+++ b/drivers/input/Makefile
@@ -6,6 +6,9 @@

obj-$(CONFIG_INPUT) += input-core.o
input-core-y := input.o input-compat.o input-mt.o ff-core.o
+ifeq ($(CONFIG_INPUT_LEDS),y)
+input-core-y += leds.o
+endif

obj-$(CONFIG_INPUT_FF_MEMLESS) += ff-memless.o
obj-$(CONFIG_INPUT_POLLDEV) += input-polldev.o
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -11,9 +11,6 @@ menuconfig NEW_LEDS
Say Y to enable Linux LED support. This allows control of supported
LEDs from both userspace and optionally, by kernel events (triggers).

- This is not related to standard keyboard LEDs which are controlled
- via the input system.
-
if NEW_LEDS

config LEDS_CLASS
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -13,6 +13,10 @@ config VT
bool "Virtual terminal" if EXPERT
depends on !S390 && !UML
select INPUT
+ select NEW_LEDS
+ select LEDS_CLASS
+ select LEDS_TRIGGERS
+ select INPUT_LEDS
default y
---help---
If you say Y here, you will get support for terminal devices with
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -33,6 +33,7 @@
#include <linux/string.h>
#include <linux/init.h>
#include <linux/slab.h>
+#include <linux/leds.h>

#include <linux/kbd_kern.h>
#include <linux/kbd_diacr.h>
@@ -130,6 +131,7 @@ static char rep; /* flag telling cha
static int shift_state = 0;

static unsigned char ledstate = 0xff; /* undefined */
+static unsigned char lockstate = 0xff; /* undefined */
static unsigned char ledioctl;

/*
@@ -961,6 +963,41 @@ static void k_brl(struct vc_data *vc, un
}
}

+/* We route VT keyboard "leds" through triggers */
+static void kbd_ledstate_trigger_activate(struct led_classdev *cdev);
+
+static struct led_trigger ledtrig_ledstate[] = {
+#define DEFINE_LEDSTATE_TRIGGER(kbd_led, nam) \
+ [kbd_led] = { \
+ .name = nam, \
+ .activate = kbd_ledstate_trigger_activate, \
+ }
+ DEFINE_LEDSTATE_TRIGGER(VC_SCROLLOCK, "kbd-scrollock"),
+ DEFINE_LEDSTATE_TRIGGER(VC_NUMLOCK, "kbd-numlock"),
+ DEFINE_LEDSTATE_TRIGGER(VC_CAPSLOCK, "kbd-capslock"),
+ DEFINE_LEDSTATE_TRIGGER(VC_KANALOCK, "kbd-kanalock"),
+#undef DEFINE_LEDSTATE_TRIGGER
+};
+
+static void kbd_lockstate_trigger_activate(struct led_classdev *cdev);
+
+static struct led_trigger ledtrig_lockstate[] = {
+#define DEFINE_LOCKSTATE_TRIGGER(kbd_led, nam) \
+ [kbd_led] = { \
+ .name = nam, \
+ .activate = kbd_lockstate_trigger_activate, \
+ }
+ DEFINE_LOCKSTATE_TRIGGER(VC_SHIFTLOCK, "kbd-shiftlock"),
+ DEFINE_LOCKSTATE_TRIGGER(VC_ALTGRLOCK, "kbd-altgrlock"),
+ DEFINE_LOCKSTATE_TRIGGER(VC_CTRLLOCK, "kbd-ctrllock"),
+ DEFINE_LOCKSTATE_TRIGGER(VC_ALTLOCK, "kbd-altlock"),
+ DEFINE_LOCKSTATE_TRIGGER(VC_SHIFTLLOCK, "kbd-shiftllock"),
+ DEFINE_LOCKSTATE_TRIGGER(VC_SHIFTRLOCK, "kbd-shiftrlock"),
+ DEFINE_LOCKSTATE_TRIGGER(VC_CTRLLLOCK, "kbd-ctrlllock"),
+ DEFINE_LOCKSTATE_TRIGGER(VC_CTRLRLOCK, "kbd-ctrlrlock"),
+#undef DEFINE_LOCKSTATE_TRIGGER
+};
+
/*
* The leds display either (i) the status of NumLock, CapsLock, ScrollLock,
* or (ii) whatever pattern of lights people want to show using KDSETLED,
@@ -995,18 +1032,25 @@ static inline unsigned char getleds(void
return kb->ledflagstate;
}

-static int kbd_update_leds_helper(struct input_handle *handle, void *data)
+/* Called on trigger connection, to set initial state */
+static void kbd_ledstate_trigger_activate(struct led_classdev *cdev)
{
- unsigned char leds = *(unsigned char *)data;
+ struct led_trigger *trigger = cdev->trigger;
+ int led = trigger - ledtrig_ledstate;

- if (test_bit(EV_LED, handle->dev->evbit)) {
- input_inject_event(handle, EV_LED, LED_SCROLLL, !!(leds & 0x01));
- input_inject_event(handle, EV_LED, LED_NUML, !!(leds & 0x02));
- input_inject_event(handle, EV_LED, LED_CAPSL, !!(leds & 0x04));
- input_inject_event(handle, EV_SYN, SYN_REPORT, 0);
- }
+ tasklet_disable(&keyboard_tasklet);
+ led_trigger_event(trigger, ledstate & (1 << led) ? LED_FULL : LED_OFF);
+ tasklet_enable(&keyboard_tasklet);
+}

- return 0;
+static void kbd_lockstate_trigger_activate(struct led_classdev *cdev)
+{
+ struct led_trigger *trigger = cdev->trigger;
+ int led = trigger - ledtrig_lockstate;
+
+ tasklet_disable(&keyboard_tasklet);
+ led_trigger_event(trigger, lockstate & (1 << led) ? LED_FULL : LED_OFF);
+ tasklet_enable(&keyboard_tasklet);
}

/**
@@ -1095,16 +1139,29 @@ static void kbd_bh(unsigned long dummy)
{
unsigned char leds;
unsigned long flags;
-
+ int i;
+
spin_lock_irqsave(&led_lock, flags);
leds = getleds();
spin_unlock_irqrestore(&led_lock, flags);

if (leds != ledstate) {
- input_handler_for_each_handle(&kbd_handler, &leds,
- kbd_update_leds_helper);
+ for (i = 0; i < ARRAY_SIZE(ledtrig_ledstate); i++)
+ if ((leds ^ ledstate) & (1 << i))
+ led_trigger_event(&ledtrig_ledstate[i],
+ leds & (1 << i)
+ ? LED_FULL : LED_OFF);
ledstate = leds;
}
+
+ if (kbd->lockstate != lockstate) {
+ for (i = 0; i < ARRAY_SIZE(ledtrig_lockstate); i++)
+ if ((kbd->lockstate ^ lockstate) & (1 << i))
+ led_trigger_event(&ledtrig_lockstate[i],
+ kbd->lockstate & (1 << i)
+ ? LED_FULL : LED_OFF);
+ lockstate = kbd->lockstate;
+ }
}

DECLARE_TASKLET_DISABLED(keyboard_tasklet, kbd_bh, 0);
@@ -1442,20 +1499,6 @@ static void kbd_disconnect(struct input_
kfree(handle);
}

-/*
- * Start keyboard handler on the new keyboard by refreshing LED state to
- * match the rest of the system.
- */
-static void kbd_start(struct input_handle *handle)
-{
- tasklet_disable(&keyboard_tasklet);
-
- if (ledstate != 0xff)
- kbd_update_leds_helper(handle, &ledstate);
-
- tasklet_enable(&keyboard_tasklet);
-}
-
static const struct input_device_id kbd_ids[] = {
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
@@ -1477,7 +1520,6 @@ static struct input_handler kbd_handler
.match = kbd_match,
.connect = kbd_connect,
.disconnect = kbd_disconnect,
- .start = kbd_start,
.name = "kbd",
.id_table = kbd_ids,
};
@@ -1501,6 +1543,20 @@ int __init kbd_init(void)
if (error)
return error;

+ for (i = 0; i < ARRAY_SIZE(ledtrig_ledstate); i++) {
+ error = led_trigger_register(&ledtrig_ledstate[i]);
+ if (error)
+ pr_err("error %d while registering trigger %s\n",
+ error, ledtrig_ledstate[i].name);
+ }
+
+ for (i = 0; i < ARRAY_SIZE(ledtrig_lockstate); i++) {
+ error = led_trigger_register(&ledtrig_lockstate[i]);
+ if (error)
+ pr_err("error %d while registering trigger %s\n",
+ error, ledtrig_lockstate[i].name);
+ }
+
tasklet_enable(&keyboard_tasklet);
tasklet_schedule(&keyboard_tasklet);

--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -79,6 +79,7 @@ struct input_value {
* @led: reflects current state of device's LEDs
* @snd: reflects current state of sound effects
* @sw: reflects current state of device's switches
+ * @leds: leds objects for the device's LEDs
* @open: this method is called when the very first user calls
* input_open_device(). The driver must prepare the device
* to start generating events (start polling thread,
@@ -164,6 +165,8 @@ struct input_dev {
unsigned long snd[BITS_TO_LONGS(SND_CNT)];
unsigned long sw[BITS_TO_LONGS(SW_CNT)];

+ struct led_classdev *leds;
+
int (*open)(struct input_dev *dev);
void (*close)(struct input_dev *dev);
int (*flush)(struct input_dev *dev, struct file *file);
@@ -531,4 +534,29 @@ int input_ff_erase(struct input_dev *dev
int input_ff_create_memless(struct input_dev *dev, void *data,
int (*play_effect)(struct input_dev *, void *, struct ff_effect *));

+#ifdef CONFIG_INPUT_LEDS
+
+void input_led_init(void);
+void input_led_exit(void);
+
+int input_led_connect(struct input_dev *dev);
+void input_led_disconnect(struct input_dev *dev);
+
+#else
+
+static inline void input_led_init(void) { }
+
+static inline void input_led_exit(void) { }
+
+static inline int input_led_connect(struct input_dev *dev)
+{
+ return 0;
+}
+
+static inline void input_led_disconnect(struct input_dev *dev)
+{
+}
+
+#endif
+
#endif
--- /dev/null
+++ b/drivers/input/leds.c
@@ -0,0 +1,272 @@
+/*
+ * LED support for the input layer
+ *
+ * Copyright 2010-2014 Samuel Thibault <samuel.thibault@ens-lyon.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/leds.h>
+#include <linux/input.h>
+
+/*
+ * Keyboard LEDs are propagated by default like the following example:
+ *
+ * VT keyboard numlock trigger
+ * -> vt::numl VT LED
+ * -> vt-numl VT trigger
+ * -> per-device inputX::numl LED
+ *
+ * Userland can however choose the trigger for the vt::numl LED, or
+ * independently choose the trigger for any inputx::numl LED.
+ *
+ *
+ * VT LED classes and triggers are registered on-demand according to
+ * existing LED devices
+ */
+
+/* Handler for VT LEDs, just triggers the corresponding VT trigger. */
+static void vt_led_set(struct led_classdev *cdev,
+ enum led_brightness brightness);
+static struct led_classdev vt_leds[LED_CNT] = {
+#define DEFINE_INPUT_LED(vt_led, nam, deftrig) \
+ [vt_led] = { \
+ .name = "vt::"nam, \
+ .max_brightness = 1, \
+ .brightness_set = vt_led_set, \
+ .default_trigger = deftrig, \
+ }
+/* Default triggers for the VT LEDs just correspond to the legacy
+ * usage. */
+ DEFINE_INPUT_LED(LED_NUML, "numl", "kbd-numlock"),
+ DEFINE_INPUT_LED(LED_CAPSL, "capsl", "kbd-capslock"),
+ DEFINE_INPUT_LED(LED_SCROLLL, "scrolll", "kbd-scrollock"),
+ DEFINE_INPUT_LED(LED_COMPOSE, "compose", NULL),
+ DEFINE_INPUT_LED(LED_KANA, "kana", "kbd-kanalock"),
+ DEFINE_INPUT_LED(LED_SLEEP, "sleep", NULL),
+ DEFINE_INPUT_LED(LED_SUSPEND, "suspend", NULL),
+ DEFINE_INPUT_LED(LED_MUTE, "mute", NULL),
+ DEFINE_INPUT_LED(LED_MISC, "misc", NULL),
+ DEFINE_INPUT_LED(LED_MAIL, "mail", NULL),
+ DEFINE_INPUT_LED(LED_CHARGING, "charging", NULL),
+};
+static const char *const vt_led_names[LED_CNT] = {
+ [LED_NUML] = "numl",
+ [LED_CAPSL] = "capsl",
+ [LED_SCROLLL] = "scrolll",
+ [LED_COMPOSE] = "compose",
+ [LED_KANA] = "kana",
+ [LED_SLEEP] = "sleep",
+ [LED_SUSPEND] = "suspend",
+ [LED_MUTE] = "mute",
+ [LED_MISC] = "misc",
+ [LED_MAIL] = "mail",
+ [LED_CHARGING] = "charging",
+};
+/* Handler for hotplug initialization */
+static void vt_led_trigger_activate(struct led_classdev *cdev);
+/* VT triggers */
+static struct led_trigger vt_led_triggers[LED_CNT] = {
+#define DEFINE_INPUT_LED_TRIGGER(vt_led, nam) \
+ [vt_led] = { \
+ .name = "vt-"nam, \
+ .activate = vt_led_trigger_activate, \
+ }
+ DEFINE_INPUT_LED_TRIGGER(LED_NUML, "numl"),
+ DEFINE_INPUT_LED_TRIGGER(LED_CAPSL, "capsl"),
+ DEFINE_INPUT_LED_TRIGGER(LED_SCROLLL, "scrolll"),
+ DEFINE_INPUT_LED_TRIGGER(LED_COMPOSE, "compose"),
+ DEFINE_INPUT_LED_TRIGGER(LED_KANA, "kana"),
+ DEFINE_INPUT_LED_TRIGGER(LED_SLEEP, "sleep"),
+ DEFINE_INPUT_LED_TRIGGER(LED_SUSPEND, "suspend"),
+ DEFINE_INPUT_LED_TRIGGER(LED_MUTE, "mute"),
+ DEFINE_INPUT_LED_TRIGGER(LED_MISC, "misc"),
+ DEFINE_INPUT_LED_TRIGGER(LED_MAIL, "mail"),
+ DEFINE_INPUT_LED_TRIGGER(LED_CHARGING, "charging"),
+};
+
+/* Lock for registration coherency */
+static DEFINE_MUTEX(vt_led_registered_lock);
+
+/* Which VT LED classes and triggers are registered */
+static unsigned long vt_led_registered[BITS_TO_LONGS(LED_CNT)];
+
+/* Number of input devices having each LED */
+static int vt_led_references[LED_CNT];
+
+static int vt_led_state[LED_CNT];
+static struct work_struct vt_led_work[LED_CNT];
+
+static void vt_led_cb(struct work_struct *work)
+{
+ int led = work - vt_led_work;
+
+ led_trigger_event(&vt_led_triggers[led], vt_led_state[led]);
+}
+
+/* VT LED state change, tell the VT trigger. */
+static void vt_led_set(struct led_classdev *cdev,
+ enum led_brightness brightness)
+{
+ int led = cdev - vt_leds;
+
+ vt_led_state[led] = !!brightness;
+ schedule_work(&vt_led_work[led]);
+}
+
+/* LED state change for some keyboard, notify that keyboard. */
+static void perdevice_input_led_set(struct led_classdev *cdev,
+ enum led_brightness brightness)
+{
+ struct input_dev *dev;
+ struct led_classdev *leds;
+ int led;
+
+ dev = cdev->dev->platform_data;
+ if (!dev)
+ /* Still initializing */
+ return;
+ leds = dev->leds;
+ led = cdev - leds;
+
+ input_event(dev, EV_LED, led, !!brightness);
+ input_event(dev, EV_SYN, SYN_REPORT, 0);
+}
+
+/* Keyboard hotplug, initialize its LED status */
+static void vt_led_trigger_activate(struct led_classdev *cdev)
+{
+ struct led_trigger *trigger = cdev->trigger;
+ int led = trigger - vt_led_triggers;
+
+ if (cdev->brightness_set)
+ cdev->brightness_set(cdev, vt_leds[led].brightness);
+}
+
+/* Free led stuff from input device, used at abortion and disconnection. */
+static void input_led_delete(struct input_dev *dev)
+{
+ if (dev) {
+ struct led_classdev *leds = dev->leds;
+ if (leds) {
+ int i;
+ for (i = 0; i < LED_CNT; i++)
+ kfree(leds[i].name);
+ kfree(leds);
+ dev->leds = NULL;
+ }
+ }
+}
+
+/* A new input device with potential LEDs to connect. */
+int input_led_connect(struct input_dev *dev)
+{
+ int i, error = 0;
+ struct led_classdev *leds;
+
+ dev->leds = leds = kcalloc(LED_CNT, sizeof(*leds), GFP_KERNEL);
+ if (!dev->leds)
+ return -ENOMEM;
+
+ /* lazily register missing VT LEDs */
+ mutex_lock(&vt_led_registered_lock);
+ for (i = 0; i < LED_CNT; i++)
+ if (vt_leds[i].name && test_bit(i, dev->ledbit)) {
+ if (!vt_led_references[i]) {
+ led_trigger_register(&vt_led_triggers[i]);
+ /* This keyboard is first to have led i,
+ * try to register it */
+ if (!led_classdev_register(NULL, &vt_leds[i]))
+ vt_led_references[i] = 1;
+ else
+ led_trigger_unregister(&vt_led_triggers[i]);
+ } else
+ vt_led_references[i]++;
+ }
+ mutex_unlock(&vt_led_registered_lock);
+
+ /* and register this device's LEDs */
+ for (i = 0; i < LED_CNT; i++)
+ if (vt_leds[i].name && test_bit(i, dev->ledbit)) {
+ leds[i].name = kasprintf(GFP_KERNEL, "%s::%s",
+ dev_name(&dev->dev),
+ vt_led_names[i]);
+ if (!leds[i].name) {
+ error = -ENOMEM;
+ goto err;
+ }
+ leds[i].max_brightness = 1;
+ leds[i].brightness_set = perdevice_input_led_set;
+ leds[i].default_trigger = vt_led_triggers[i].name;
+ }
+
+ /* No issue so far, we can register for real. */
+ for (i = 0; i < LED_CNT; i++)
+ if (leds[i].name) {
+ led_classdev_register(&dev->dev, &leds[i]);
+ leds[i].dev->platform_data = dev;
+ perdevice_input_led_set(&leds[i],
+ vt_leds[i].brightness);
+ }
+
+ return 0;
+
+err:
+ input_led_delete(dev);
+ return error;
+}
+
+/*
+ * Disconnected input device. Clean it, and deregister now-useless VT LEDs
+ * and triggers.
+ */
+void input_led_disconnect(struct input_dev *dev)
+{
+ int i;
+ struct led_classdev *leds = dev->leds;
+
+ for (i = 0; i < LED_CNT; i++)
+ if (leds[i].name)
+ led_classdev_unregister(&leds[i]);
+
+ input_led_delete(dev);
+
+ mutex_lock(&vt_led_registered_lock);
+ for (i = 0; i < LED_CNT; i++) {
+ if (!vt_leds[i].name || !test_bit(i, dev->ledbit))
+ continue;
+
+ vt_led_references[i]--;
+ if (vt_led_references[i]) {
+ /* Still some devices needing it */
+ continue;
+ }
+
+ led_classdev_unregister(&vt_leds[i]);
+ led_trigger_unregister(&vt_led_triggers[i]);
+ clear_bit(i, vt_led_registered);
+ }
+ mutex_unlock(&vt_led_registered_lock);
+}
+
+void __init input_led_init(void)
+{
+ unsigned i;
+
+ for (i = 0; i < LED_CNT; i++)
+ INIT_WORK(&vt_led_work[i], vt_led_cb);
+}
+
+void __exit input_led_exit(void)
+{
+ unsigned i;
+
+ for (i = 0; i < LED_CNT; i++)
+ cancel_work_sync(&vt_led_work[i]);
+}