input: add keycombo, a general key combo driver.

Keycombo lets you provide a key up and key down function, and an
optional time delay for key down. The driver will call the key
down function after the specified key combo has been held for the
speicified time delay. After you release the combo, if the key down
has happened, it calls key up.

Change-Id: I6a9a94e96a8f58fadd908fd1dc7944b9102a089f
Signed-off-by: Daniel Rosenberg <drosen@google.com>

3 files changed, 272 insertions, 0 deletions

diff --git a/drivers/input/Kconfig b/drivers/input/Kconfig
index 3ad49c1f0a30..9be8d5c3ca70 100644
--- a/drivers/input/Kconfig
+++ b/drivers/input/Kconfig
@@ -183,6 +183,15 @@ config INPUT_KEYRESET
 	  To compile this driver as a module, choose M here: the
 	  module will be called keyreset.
 
+config INPUT_KEYCOMBO
+	tristate "Key combo"
+	depends on INPUT
+	---help---
+	  Say Y here if you want to take action when some keys are pressed;
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called keycombo.
+
 comment "Input Device Drivers"
 
 source "drivers/input/keyboard/Kconfig"
diff --git a/drivers/input/Makefile b/drivers/input/Makefile
index 191ea43d0800..ee4c06520bb4 100644
--- a/drivers/input/Makefile
+++ b/drivers/input/Makefile
@@ -26,3 +26,5 @@ obj-$(CONFIG_INPUT_MISC)	+= misc/
 
 obj-$(CONFIG_INPUT_APMPOWER)	+= apm-power.o
 obj-$(CONFIG_INPUT_KEYRESET)	+= keyreset.o
+obj-$(CONFIG_INPUT_KEYCOMBO)	+= keycombo.o
+
diff --git a/drivers/input/keycombo.c b/drivers/input/keycombo.c
new file mode 100644
index 000000000000..2fba451b91d5
--- /dev/null
+++ b/drivers/input/keycombo.c
@@ -0,0 +1,261 @@
+/* drivers/input/keycombo.c
+ *
+ * Copyright (C) 2014 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/input.h>
+#include <linux/keycombo.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+struct keycombo_state {
+	struct input_handler input_handler;
+	unsigned long keybit[BITS_TO_LONGS(KEY_CNT)];
+	unsigned long upbit[BITS_TO_LONGS(KEY_CNT)];
+	unsigned long key[BITS_TO_LONGS(KEY_CNT)];
+	spinlock_t lock;
+	struct  workqueue_struct *wq;
+	int key_down_target;
+	int key_down;
+	int key_up;
+	struct delayed_work key_down_work;
+	int delay;
+	struct work_struct key_up_work;
+	void (*key_up_fn)(void *);
+	void (*key_down_fn)(void *);
+	void *priv;
+	int key_is_down;
+	struct wakeup_source combo_held_wake_source;
+	struct wakeup_source combo_up_wake_source;
+};
+
+static void do_key_down(struct work_struct *work)
+{
+	struct delayed_work *dwork = container_of(work, struct delayed_work,
+									work);
+	struct keycombo_state *state = container_of(dwork,
+					struct keycombo_state, key_down_work);
+	if (state->key_down_fn)
+		state->key_down_fn(state->priv);
+}
+
+static void do_key_up(struct work_struct *work)
+{
+	struct keycombo_state *state = container_of(work, struct keycombo_state,
+								key_up_work);
+	if (state->key_up_fn)
+		state->key_up_fn(state->priv);
+	__pm_relax(&state->combo_up_wake_source);
+}
+
+static void keycombo_event(struct input_handle *handle, unsigned int type,
+		unsigned int code, int value)
+{
+	unsigned long flags;
+	struct keycombo_state *state = handle->private;
+
+	if (type != EV_KEY)
+		return;
+
+	if (code >= KEY_MAX)
+		return;
+
+	if (!test_bit(code, state->keybit))
+		return;
+
+	spin_lock_irqsave(&state->lock, flags);
+	if (!test_bit(code, state->key) == !value)
+		goto done;
+	__change_bit(code, state->key);
+	if (test_bit(code, state->upbit)) {
+		if (value)
+			state->key_up++;
+		else
+			state->key_up--;
+	} else {
+		if (value)
+			state->key_down++;
+		else
+			state->key_down--;
+	}
+	if (state->key_down == state->key_down_target && state->key_up == 0) {
+		__pm_stay_awake(&state->combo_held_wake_source);
+		state->key_is_down = 1;
+		if (queue_delayed_work(state->wq, &state->key_down_work,
+								state->delay))
+			pr_debug("Key down work already queued!");
+	} else if (state->key_is_down) {
+		if (!cancel_delayed_work(&state->key_down_work)) {
+			__pm_stay_awake(&state->combo_up_wake_source);
+			queue_work(state->wq, &state->key_up_work);
+		}
+		__pm_relax(&state->combo_held_wake_source);
+		state->key_is_down = 0;
+	}
+done:
+	spin_unlock_irqrestore(&state->lock, flags);
+}
+
+static int keycombo_connect(struct input_handler *handler,
+		struct input_dev *dev,
+		const struct input_device_id *id)
+{
+	int i;
+	int ret;
+	struct input_handle *handle;
+	struct keycombo_state *state =
+		container_of(handler, struct keycombo_state, input_handler);
+	for (i = 0; i < KEY_MAX; i++) {
+		if (test_bit(i, state->keybit) && test_bit(i, dev->keybit))
+			break;
+	}
+	if (i == KEY_MAX)
+		return -ENODEV;
+
+	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
+	if (!handle)
+		return -ENOMEM;
+
+	handle->dev = dev;
+	handle->handler = handler;
+	handle->name = KEYCOMBO_NAME;
+	handle->private = state;
+
+	ret = input_register_handle(handle);
+	if (ret)
+		goto err_input_register_handle;
+
+	ret = input_open_device(handle);
+	if (ret)
+		goto err_input_open_device;
+
+	return 0;
+
+err_input_open_device:
+	input_unregister_handle(handle);
+err_input_register_handle:
+	kfree(handle);
+	return ret;
+}
+
+static void keycombo_disconnect(struct input_handle *handle)
+{
+	input_close_device(handle);
+	input_unregister_handle(handle);
+	kfree(handle);
+}
+
+static const struct input_device_id keycombo_ids[] = {
+		{
+				.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
+				.evbit = { BIT_MASK(EV_KEY) },
+		},
+		{ },
+};
+MODULE_DEVICE_TABLE(input, keycombo_ids);
+
+static int keycombo_probe(struct platform_device *pdev)
+{
+	int ret;
+	int key, *keyp;
+	struct keycombo_state *state;
+	struct keycombo_platform_data *pdata = pdev->dev.platform_data;
+
+	if (!pdata)
+		return -EINVAL;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	spin_lock_init(&state->lock);
+	keyp = pdata->keys_down;
+	while ((key = *keyp++)) {
+		if (key >= KEY_MAX)
+			continue;
+		state->key_down_target++;
+		__set_bit(key, state->keybit);
+	}
+	if (pdata->keys_up) {
+		keyp = pdata->keys_up;
+		while ((key = *keyp++)) {
+			if (key >= KEY_MAX)
+				continue;
+			__set_bit(key, state->keybit);
+			__set_bit(key, state->upbit);
+		}
+	}
+
+	state->wq = alloc_ordered_workqueue("keycombo", 0);
+	if (!state->wq)
+		return -ENOMEM;
+
+	state->priv = pdata->priv;
+
+	if (pdata->key_down_fn)
+		state->key_down_fn = pdata->key_down_fn;
+	INIT_DELAYED_WORK(&state->key_down_work, do_key_down);
+
+	if (pdata->key_up_fn)
+		state->key_up_fn = pdata->key_up_fn;
+	INIT_WORK(&state->key_up_work, do_key_up);
+
+	wakeup_source_init(&state->combo_held_wake_source, "key combo");
+	wakeup_source_init(&state->combo_up_wake_source, "key combo up");
+	state->delay = msecs_to_jiffies(pdata->key_down_delay);
+
+	state->input_handler.event = keycombo_event;
+	state->input_handler.connect = keycombo_connect;
+	state->input_handler.disconnect = keycombo_disconnect;
+	state->input_handler.name = KEYCOMBO_NAME;
+	state->input_handler.id_table = keycombo_ids;
+	ret = input_register_handler(&state->input_handler);
+	if (ret) {
+		kfree(state);
+		return ret;
+	}
+	platform_set_drvdata(pdev, state);
+	return 0;
+}
+
+int keycombo_remove(struct platform_device *pdev)
+{
+	struct keycombo_state *state = platform_get_drvdata(pdev);
+	input_unregister_handler(&state->input_handler);
+	destroy_workqueue(state->wq);
+	kfree(state);
+	return 0;
+}
+
+
+struct platform_driver keycombo_driver = {
+		.driver.name = KEYCOMBO_NAME,
+		.probe = keycombo_probe,
+		.remove = keycombo_remove,
+};
+
+static int __init keycombo_init(void)
+{
+	return platform_driver_register(&keycombo_driver);
+}
+
+static void __exit keycombo_exit(void)
+{
+	return platform_driver_unregister(&keycombo_driver);
+}
+
+module_init(keycombo_init);
+module_exit(keycombo_exit);