input: Add keyreset driver.

Add a platform device in the board file to specify a reset key-combo.
The first time the key-combo is detected a work function that syncs
the filesystems is scheduled. If all the keys are released and then
pressed again, it calls panic. Reboot on panic should be set for
this to work.

Change-Id: I9d54283ca1fba45e4b1ae1a407524cdda8171143
Signed-off-by: Arve Hjønnevåg <arve@android.com>

3 files changed, 240 insertions, 0 deletions

diff --git a/drivers/input/Kconfig b/drivers/input/Kconfig
index 07c2cd43109c..dd62135e7045 100644
--- a/drivers/input/Kconfig
+++ b/drivers/input/Kconfig
@@ -161,6 +161,15 @@ config INPUT_APMPOWER
 	  To compile this driver as a module, choose M here: the
 	  module will be called apm-power.
 
+config INPUT_KEYRESET
+	tristate "Reset key"
+	depends on INPUT
+	---help---
+	  Say Y here if you want to reboot when some keys are pressed;
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called keyreset.
+
 config XEN_KBDDEV_FRONTEND
 	tristate "Xen virtual keyboard and mouse support"
 	depends on XEN_FBDEV_FRONTEND
diff --git a/drivers/input/Makefile b/drivers/input/Makefile
index 7ad212d31f99..3c7125758b7f 100644
--- a/drivers/input/Makefile
+++ b/drivers/input/Makefile
@@ -24,5 +24,6 @@ obj-$(CONFIG_INPUT_TOUCHSCREEN)	+= touchscreen/
 obj-$(CONFIG_INPUT_MISC)	+= misc/
 
 obj-$(CONFIG_INPUT_APMPOWER)	+= apm-power.o
+obj-$(CONFIG_INPUT_KEYRESET)	+= keyreset.o
 
 obj-$(CONFIG_XEN_KBDDEV_FRONTEND)	+= xen-kbdfront.o
diff --git a/drivers/input/keyreset.c b/drivers/input/keyreset.c
new file mode 100644
index 000000000000..b51350602fc3
--- /dev/null
+++ b/drivers/input/keyreset.c
@@ -0,0 +1,230 @@
+/* drivers/input/keyreset.c
+ *
+ * Copyright (C) 2008 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/keyreset.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/syscalls.h>
+
+
+struct keyreset_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;
+	int key_down_target;
+	int key_down;
+	int key_up;
+	int restart_disabled;
+};
+
+int restart_requested;
+static void deferred_restart(struct work_struct *dummy)
+{
+	restart_requested = 2;
+	sys_sync();
+	restart_requested = 3;
+	kernel_restart(NULL);
+}
+static DECLARE_WORK(restart_work, deferred_restart);
+
+static void keyreset_event(struct input_handle *handle, unsigned int type,
+			   unsigned int code, int value)
+{
+	unsigned long flags;
+	struct keyreset_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->restart_disabled = 1;
+			state->key_up++;
+		} else
+			state->key_up--;
+	} else {
+		if (value)
+			state->key_down++;
+		else
+			state->key_down--;
+	}
+	if (state->key_down == 0 && state->key_up == 0)
+		state->restart_disabled = 0;
+
+	pr_debug("reset key changed %d %d new state %d-%d-%d\n", code, value,
+		 state->key_down, state->key_up, state->restart_disabled);
+
+	if (value && !state->restart_disabled &&
+	    state->key_down == state->key_down_target) {
+		state->restart_disabled = 1;
+		if (restart_requested)
+			panic("keyboard reset failed, %d", restart_requested);
+		pr_info("keyboard reset\n");
+		schedule_work(&restart_work);
+		restart_requested = 1;
+	}
+done:
+	spin_unlock_irqrestore(&state->lock, flags);
+}
+
+static int keyreset_connect(struct input_handler *handler,
+					  struct input_dev *dev,
+					  const struct input_device_id *id)
+{
+	int i;
+	int ret;
+	struct input_handle *handle;
+	struct keyreset_state *state =
+		container_of(handler, struct keyreset_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 = "keyreset";
+	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;
+
+	pr_info("using input dev %s for key reset\n", dev->name);
+
+	return 0;
+
+err_input_open_device:
+	input_unregister_handle(handle);
+err_input_register_handle:
+	kfree(handle);
+	return ret;
+}
+
+static void keyreset_disconnect(struct input_handle *handle)
+{
+	input_close_device(handle);
+	input_unregister_handle(handle);
+	kfree(handle);
+}
+
+static const struct input_device_id keyreset_ids[] = {
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
+		.evbit = { BIT_MASK(EV_KEY) },
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(input, keyreset_ids);
+
+static int keyreset_probe(struct platform_device *pdev)
+{
+	int ret;
+	int key, *keyp;
+	struct keyreset_state *state;
+	struct keyreset_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->input_handler.event = keyreset_event;
+	state->input_handler.connect = keyreset_connect;
+	state->input_handler.disconnect = keyreset_disconnect;
+	state->input_handler.name = KEYRESET_NAME;
+	state->input_handler.id_table = keyreset_ids;
+	ret = input_register_handler(&state->input_handler);
+	if (ret) {
+		kfree(state);
+		return ret;
+	}
+	platform_set_drvdata(pdev, state);
+	return 0;
+}
+
+int keyreset_remove(struct platform_device *pdev)
+{
+	struct keyreset_state *state = platform_get_drvdata(pdev);
+	input_unregister_handler(&state->input_handler);
+	kfree(state);
+	return 0;
+}
+
+
+struct platform_driver keyreset_driver = {
+	.driver.name = KEYRESET_NAME,
+	.probe = keyreset_probe,
+	.remove = keyreset_remove,
+};
+
+static int __init keyreset_init(void)
+{
+	return platform_driver_register(&keyreset_driver);
+}
+
+static void __exit keyreset_exit(void)
+{
+	return platform_driver_unregister(&keyreset_driver);
+}
+
+module_init(keyreset_init);
+module_exit(keyreset_exit);