platform/x86: Add LG Gram laptop special features driver

A driver for LG Gram laptop supporting features not available through the
standard interfaces:

- Support for the 5 Fn keys that generate ACPI or WMI events.

- Two software controlled LEDs: keyboard backlight (also controlled by
  hardware) and touchpad LED.

- Extra features: reader mode, Fn lock, cooling mode, USB charge mode, and
  maximal battery charging level.

Signed-off-by: Matan Ziv-Av <matan@svgalib.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

3 files changed, 715 insertions, 0 deletions

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 4283239115ca..1991608549d5 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -367,6 +367,20 @@ config HP_WMI
 	 To compile this driver as a module, choose M here: the module will
 	 be called hp-wmi.
 
+config LG_LAPTOP
+	tristate "LG Laptop Extras"
+	depends on ACPI
+	depends on ACPI_WMI
+	depends on INPUT
+	select INPUT_SPARSEKMAP
+	select LEDS_CLASS
+	help
+	 This driver adds support for hotkeys as well as control of keyboard
+	 backlight, battery maximum charge level and various other ACPI
+	 features.
+
+	 If you have an LG Gram laptop, say Y or M here.
+
 config MSI_LAPTOP
 	tristate "MSI Laptop Extras"
 	depends on ACPI
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 4e2712c9c0b0..395c8ff12bd1 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_ASUS_NB_WMI)	+= asus-nb-wmi.o
 obj-$(CONFIG_ASUS_WIRELESS)	+= asus-wireless.o
 obj-$(CONFIG_EEEPC_LAPTOP)	+= eeepc-laptop.o
 obj-$(CONFIG_EEEPC_WMI)		+= eeepc-wmi.o
+obj-$(CONFIG_LG_LAPTOP)		+= lg-laptop.o
 obj-$(CONFIG_MSI_LAPTOP)	+= msi-laptop.o
 obj-$(CONFIG_ACPI_CMPC)		+= classmate-laptop.o
 obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o
diff --git a/drivers/platform/x86/lg-laptop.c b/drivers/platform/x86/lg-laptop.c
new file mode 100644
index 000000000000..c0bb1f864dfe
--- /dev/null
+++ b/drivers/platform/x86/lg-laptop.c
@@ -0,0 +1,700 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * lg-laptop.c - LG Gram ACPI features and hotkeys Driver
+ *
+ * Copyright (C) 2018 Matan Ziv-Av <matan@svgalib.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/input.h>
+#include <linux/input/sparse-keymap.h>
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#define LED_DEVICE(_name, max) struct led_classdev _name = { \
+	.name           = __stringify(_name),   \
+	.max_brightness = max,                  \
+	.brightness_set = _name##_set,          \
+	.brightness_get = _name##_get,          \
+}
+
+MODULE_AUTHOR("Matan Ziv-Av");
+MODULE_DESCRIPTION("LG WMI Hotkey Driver");
+MODULE_LICENSE("GPL");
+
+#define WMI_EVENT_GUID0	"E4FB94F9-7F2B-4173-AD1A-CD1D95086248"
+#define WMI_EVENT_GUID1	"023B133E-49D1-4E10-B313-698220140DC2"
+#define WMI_EVENT_GUID2	"37BE1AC0-C3F2-4B1F-BFBE-8FDEAF2814D6"
+#define WMI_EVENT_GUID3	"911BAD44-7DF8-4FBB-9319-BABA1C4B293B"
+#define WMI_METHOD_WMAB "C3A72B38-D3EF-42D3-8CBB-D5A57049F66D"
+#define WMI_METHOD_WMBB "2B4F501A-BD3C-4394-8DCF-00A7D2BC8210"
+#define WMI_EVENT_GUID  WMI_EVENT_GUID0
+
+#define WMAB_METHOD     "\\XINI.WMAB"
+#define WMBB_METHOD     "\\XINI.WMBB"
+#define SB_GGOV_METHOD  "\\_SB.GGOV"
+#define GOV_TLED        0x2020008
+#define WM_GET          1
+#define WM_SET          2
+#define WM_KEY_LIGHT    0x400
+#define WM_TLED         0x404
+#define WM_FN_LOCK      0x407
+#define WM_BATT_LIMIT   0x61
+#define WM_READER_MODE  0xBF
+#define WM_FAN_MODE	0x33
+#define WMBB_USB_CHARGE 0x10B
+#define WMBB_BATT_LIMIT 0x10C
+
+#define PLATFORM_NAME   "lg-laptop"
+
+MODULE_ALIAS("wmi:" WMI_EVENT_GUID0);
+MODULE_ALIAS("wmi:" WMI_EVENT_GUID1);
+MODULE_ALIAS("wmi:" WMI_EVENT_GUID2);
+MODULE_ALIAS("wmi:" WMI_EVENT_GUID3);
+MODULE_ALIAS("wmi:" WMI_METHOD_WMAB);
+MODULE_ALIAS("wmi:" WMI_METHOD_WMBB);
+MODULE_ALIAS("acpi*:LGEX0815:*");
+
+static struct platform_device *pf_device;
+static struct input_dev *wmi_input_dev;
+
+static u32 inited;
+#define INIT_INPUT_WMI_0        0x01
+#define INIT_INPUT_WMI_2        0x02
+#define INIT_INPUT_ACPI         0x04
+#define INIT_TPAD_LED           0x08
+#define INIT_KBD_LED            0x10
+#define INIT_SPARSE_KEYMAP        0x80
+
+static const struct key_entry wmi_keymap[] = {
+	{KE_KEY, 0x70, {KEY_F15} },	 /* LG control panel (F1) */
+	{KE_KEY, 0x74, {KEY_F13} },	 /* Touchpad toggle (F5) */
+	{KE_KEY, 0xf020000, {KEY_F14} }, /* Read mode (F9) */
+	{KE_KEY, 0x10000000, {KEY_F16} },/* Keyboard backlight (F8) - pressing
+					  * this key both sends an event and
+					  * changes backlight level.
+					  */
+	{KE_KEY, 0x80, {KEY_RFKILL} },
+	{KE_END, 0}
+};
+
+static int ggov(u32 arg0)
+{
+	union acpi_object args[1];
+	union acpi_object *r;
+	acpi_status status;
+	acpi_handle handle;
+	struct acpi_object_list arg;
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	int res;
+
+	args[0].type = ACPI_TYPE_INTEGER;
+	args[0].integer.value = arg0;
+
+	status = acpi_get_handle(NULL, (acpi_string) SB_GGOV_METHOD, &handle);
+	if (ACPI_FAILURE(status)) {
+		pr_err("Cannot get handle");
+		return -ENODEV;
+	}
+
+	arg.count = 1;
+	arg.pointer = args;
+
+	status = acpi_evaluate_object(handle, NULL, &arg, &buffer);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_err(handle, "GGOV: call failed.\n");
+		return -EINVAL;
+	}
+
+	r = buffer.pointer;
+	if (r->type != ACPI_TYPE_INTEGER) {
+		kfree(r);
+		return -EINVAL;
+	}
+
+	res = r->integer.value;
+	kfree(r);
+
+	return res;
+}
+
+static union acpi_object *lg_wmab(u32 method, u32 arg1, u32 arg2)
+{
+	union acpi_object args[3];
+	acpi_status status;
+	acpi_handle handle;
+	struct acpi_object_list arg;
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+
+	args[0].type = ACPI_TYPE_INTEGER;
+	args[0].integer.value = method;
+	args[1].type = ACPI_TYPE_INTEGER;
+	args[1].integer.value = arg1;
+	args[2].type = ACPI_TYPE_INTEGER;
+	args[2].integer.value = arg2;
+
+	status = acpi_get_handle(NULL, (acpi_string) WMAB_METHOD, &handle);
+	if (ACPI_FAILURE(status)) {
+		pr_err("Cannot get handle");
+		return NULL;
+	}
+
+	arg.count = 3;
+	arg.pointer = args;
+
+	status = acpi_evaluate_object(handle, NULL, &arg, &buffer);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_err(handle, "WMAB: call failed.\n");
+		return NULL;
+	}
+
+	return buffer.pointer;
+}
+
+static union acpi_object *lg_wmbb(u32 method_id, u32 arg1, u32 arg2)
+{
+	union acpi_object args[3];
+	acpi_status status;
+	acpi_handle handle;
+	struct acpi_object_list arg;
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	u8 buf[32];
+
+	*(u32 *)buf = method_id;
+	*(u32 *)(buf + 4) = arg1;
+	*(u32 *)(buf + 16) = arg2;
+	args[0].type = ACPI_TYPE_INTEGER;
+	args[0].integer.value = 0; /* ignored */
+	args[1].type = ACPI_TYPE_INTEGER;
+	args[1].integer.value = 1; /* Must be 1 or 2. Does not matter which */
+	args[2].type = ACPI_TYPE_BUFFER;
+	args[2].buffer.length = 32;
+	args[2].buffer.pointer = buf;
+
+	status = acpi_get_handle(NULL, (acpi_string)WMBB_METHOD, &handle);
+	if (ACPI_FAILURE(status)) {
+		pr_err("Cannot get handle");
+		return NULL;
+	}
+
+	arg.count = 3;
+	arg.pointer = args;
+
+	status = acpi_evaluate_object(handle, NULL, &arg, &buffer);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_err(handle, "WMAB: call failed.\n");
+		return NULL;
+	}
+
+	return (union acpi_object *)buffer.pointer;
+}
+
+static void wmi_notify(u32 value, void *context)
+{
+	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	acpi_status status;
+	long data = (long)context;
+
+	pr_debug("event guid %li\n", data);
+	status = wmi_get_event_data(value, &response);
+	if (ACPI_FAILURE(status)) {
+		pr_err("Bad event status 0x%x\n", status);
+		return;
+	}
+
+	obj = (union acpi_object *)response.pointer;
+	if (!obj)
+		return;
+
+	if (obj->type == ACPI_TYPE_INTEGER) {
+		int eventcode = obj->integer.value;
+		struct key_entry *key;
+
+		key =
+		    sparse_keymap_entry_from_scancode(wmi_input_dev, eventcode);
+		if (key && key->type == KE_KEY)
+			sparse_keymap_report_entry(wmi_input_dev, key, 1, true);
+	}
+
+	pr_debug("Type: %i    Eventcode: 0x%llx\n", obj->type,
+		 obj->integer.value);
+	kfree(response.pointer);
+}
+
+static void wmi_input_setup(void)
+{
+	acpi_status status;
+
+	wmi_input_dev = input_allocate_device();
+	if (wmi_input_dev) {
+		wmi_input_dev->name = "LG WMI hotkeys";
+		wmi_input_dev->phys = "wmi/input0";
+		wmi_input_dev->id.bustype = BUS_HOST;
+
+		if (sparse_keymap_setup(wmi_input_dev, wmi_keymap, NULL) ||
+		    input_register_device(wmi_input_dev)) {
+			pr_info("Cannot initialize input device");
+			input_free_device(wmi_input_dev);
+			return;
+		}
+
+		inited |= INIT_SPARSE_KEYMAP;
+		status = wmi_install_notify_handler(WMI_EVENT_GUID0, wmi_notify,
+						    (void *)0);
+		if (ACPI_SUCCESS(status))
+			inited |= INIT_INPUT_WMI_0;
+
+		status = wmi_install_notify_handler(WMI_EVENT_GUID2, wmi_notify,
+						    (void *)2);
+		if (ACPI_SUCCESS(status))
+			inited |= INIT_INPUT_WMI_2;
+	} else {
+		pr_info("Cannot allocate input device");
+	}
+}
+
+static void acpi_notify(struct acpi_device *device, u32 event)
+{
+	struct key_entry *key;
+
+	acpi_handle_debug(device->handle, "notify: %d\n", event);
+	if (inited & INIT_SPARSE_KEYMAP) {
+		key = sparse_keymap_entry_from_scancode(wmi_input_dev, 0x80);
+		if (key && key->type == KE_KEY)
+			sparse_keymap_report_entry(wmi_input_dev, key, 1, true);
+	}
+}
+
+static ssize_t fan_mode_store(struct device *dev,
+			      struct device_attribute *attr,
+			      const char *buffer, size_t count)
+{
+	bool value;
+	union acpi_object *r;
+	u32 m;
+	int ret;
+
+	ret = kstrtobool(buffer, &value);
+	if (ret)
+		return ret;
+
+	r = lg_wmab(WM_FAN_MODE, WM_GET, 0);
+	if (!r)
+		return -EIO;
+
+	if (r->type != ACPI_TYPE_INTEGER) {
+		kfree(r);
+		return -EIO;
+	}
+
+	m = r->integer.value;
+	kfree(r);
+	r = lg_wmab(WM_FAN_MODE, WM_SET, (m & 0xffffff0f) | (value << 4));
+	kfree(r);
+	r = lg_wmab(WM_FAN_MODE, WM_SET, (m & 0xfffffff0) | value);
+	kfree(r);
+
+	return count;
+}
+
+static ssize_t fan_mode_show(struct device *dev,
+			     struct device_attribute *attr, char *buffer)
+{
+	unsigned int status;
+	union acpi_object *r;
+
+	r = lg_wmab(WM_FAN_MODE, WM_GET, 0);
+	if (!r)
+		return -EIO;
+
+	if (r->type != ACPI_TYPE_INTEGER) {
+		kfree(r);
+		return -EIO;
+	}
+
+	status = r->integer.value & 0x01;
+	kfree(r);
+
+	return snprintf(buffer, PAGE_SIZE, "%d\n", status);
+}
+
+static ssize_t usb_charge_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buffer, size_t count)
+{
+	bool value;
+	union acpi_object *r;
+	int ret;
+
+	ret = kstrtobool(buffer, &value);
+	if (ret)
+		return ret;
+
+	r = lg_wmbb(WMBB_USB_CHARGE, WM_SET, value);
+	if (!r)
+		return -EIO;
+
+	kfree(r);
+	return count;
+}
+
+static ssize_t usb_charge_show(struct device *dev,
+			       struct device_attribute *attr, char *buffer)
+{
+	unsigned int status;
+	union acpi_object *r;
+
+	r = lg_wmbb(WMBB_USB_CHARGE, WM_GET, 0);
+	if (!r)
+		return -EIO;
+
+	if (r->type != ACPI_TYPE_BUFFER) {
+		kfree(r);
+		return -EIO;
+	}
+
+	status = !!r->buffer.pointer[0x10];
+
+	kfree(r);
+
+	return snprintf(buffer, PAGE_SIZE, "%d\n", status);
+}
+
+static ssize_t reader_mode_store(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buffer, size_t count)
+{
+	bool value;
+	union acpi_object *r;
+	int ret;
+
+	ret = kstrtobool(buffer, &value);
+	if (ret)
+		return ret;
+
+	r = lg_wmab(WM_READER_MODE, WM_SET, value);
+	if (!r)
+		return -EIO;
+
+	kfree(r);
+	return count;
+}
+
+static ssize_t reader_mode_show(struct device *dev,
+				struct device_attribute *attr, char *buffer)
+{
+	unsigned int status;
+	union acpi_object *r;
+
+	r = lg_wmab(WM_READER_MODE, WM_GET, 0);
+	if (!r)
+		return -EIO;
+
+	if (r->type != ACPI_TYPE_INTEGER) {
+		kfree(r);
+		return -EIO;
+	}
+
+	status = !!r->integer.value;
+
+	kfree(r);
+
+	return snprintf(buffer, PAGE_SIZE, "%d\n", status);
+}
+
+static ssize_t fn_lock_store(struct device *dev,
+			     struct device_attribute *attr,
+			     const char *buffer, size_t count)
+{
+	bool value;
+	union acpi_object *r;
+	int ret;
+
+	ret = kstrtobool(buffer, &value);
+	if (ret)
+		return ret;
+
+	r = lg_wmab(WM_FN_LOCK, WM_SET, value);
+	if (!r)
+		return -EIO;
+
+	kfree(r);
+	return count;
+}
+
+static ssize_t fn_lock_show(struct device *dev,
+			    struct device_attribute *attr, char *buffer)
+{
+	unsigned int status;
+	union acpi_object *r;
+
+	r = lg_wmab(WM_FN_LOCK, WM_GET, 0);
+	if (!r)
+		return -EIO;
+
+	if (r->type != ACPI_TYPE_BUFFER) {
+		kfree(r);
+		return -EIO;
+	}
+
+	status = !!r->buffer.pointer[0];
+	kfree(r);
+
+	return snprintf(buffer, PAGE_SIZE, "%d\n", status);
+}
+
+static ssize_t battery_care_limit_store(struct device *dev,
+					struct device_attribute *attr,
+					const char *buffer, size_t count)
+{
+	unsigned long value;
+	int ret;
+
+	ret = kstrtoul(buffer, 10, &value);
+	if (ret)
+		return ret;
+
+	if (value == 100 || value == 80) {
+		union acpi_object *r;
+
+		r = lg_wmab(WM_BATT_LIMIT, WM_SET, value);
+		if (!r)
+			return -EIO;
+
+		kfree(r);
+		return count;
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t battery_care_limit_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buffer)
+{
+	unsigned int status;
+	union acpi_object *r;
+
+	r = lg_wmab(WM_BATT_LIMIT, WM_GET, 0);
+	if (!r)
+		return -EIO;
+
+	if (r->type != ACPI_TYPE_INTEGER) {
+		kfree(r);
+		return -EIO;
+	}
+
+	status = r->integer.value;
+	kfree(r);
+	if (status != 80 && status != 100)
+		status = 0;
+
+	return snprintf(buffer, PAGE_SIZE, "%d\n", status);
+}
+
+static DEVICE_ATTR_RW(fan_mode);
+static DEVICE_ATTR_RW(usb_charge);
+static DEVICE_ATTR_RW(reader_mode);
+static DEVICE_ATTR_RW(fn_lock);
+static DEVICE_ATTR_RW(battery_care_limit);
+
+static struct attribute *dev_attributes[] = {
+	&dev_attr_fan_mode.attr,
+	&dev_attr_usb_charge.attr,
+	&dev_attr_reader_mode.attr,
+	&dev_attr_fn_lock.attr,
+	&dev_attr_battery_care_limit.attr,
+	NULL
+};
+
+static const struct attribute_group dev_attribute_group = {
+	.attrs = dev_attributes,
+};
+
+static void tpad_led_set(struct led_classdev *cdev,
+			 enum led_brightness brightness)
+{
+	union acpi_object *r;
+
+	r = lg_wmab(WM_TLED, WM_SET, brightness > LED_OFF);
+	kfree(r);
+}
+
+static enum led_brightness tpad_led_get(struct led_classdev *cdev)
+{
+	return ggov(GOV_TLED) > 0 ? LED_ON : LED_OFF;
+}
+
+static LED_DEVICE(tpad_led, 1);
+
+static void kbd_backlight_set(struct led_classdev *cdev,
+			      enum led_brightness brightness)
+{
+	u32 val;
+	union acpi_object *r;
+
+	val = 0x22;
+	if (brightness <= LED_OFF)
+		val = 0;
+	if (brightness >= LED_FULL)
+		val = 0x24;
+	r = lg_wmab(WM_KEY_LIGHT, WM_SET, val);
+	kfree(r);
+}
+
+static enum led_brightness kbd_backlight_get(struct led_classdev *cdev)
+{
+	union acpi_object *r;
+	int val;
+
+	r = lg_wmab(WM_KEY_LIGHT, WM_GET, 0);
+
+	if (!r)
+		return LED_OFF;
+
+	if (r->type != ACPI_TYPE_BUFFER || r->buffer.pointer[1] != 0x05) {
+		kfree(r);
+		return LED_OFF;
+	}
+
+	switch (r->buffer.pointer[0] & 0x27) {
+	case 0x24:
+		val = LED_FULL;
+		break;
+	case 0x22:
+		val = LED_HALF;
+		break;
+	default:
+		val = LED_OFF;
+	}
+
+	kfree(r);
+
+	return val;
+}
+
+static LED_DEVICE(kbd_backlight, 255);
+
+static void wmi_input_destroy(void)
+{
+	if (inited & INIT_INPUT_WMI_2)
+		wmi_remove_notify_handler(WMI_EVENT_GUID2);
+
+	if (inited & INIT_INPUT_WMI_0)
+		wmi_remove_notify_handler(WMI_EVENT_GUID0);
+
+	if (inited & INIT_SPARSE_KEYMAP)
+		input_unregister_device(wmi_input_dev);
+
+	inited &= ~(INIT_INPUT_WMI_0 | INIT_INPUT_WMI_2 | INIT_SPARSE_KEYMAP);
+}
+
+static struct platform_driver pf_driver = {
+	.driver = {
+		   .name = PLATFORM_NAME,
+	}
+};
+
+static int acpi_add(struct acpi_device *device)
+{
+	int ret;
+
+	if (pf_device)
+		return 0;
+
+	ret = platform_driver_register(&pf_driver);
+	if (ret)
+		return ret;
+
+	pf_device = platform_device_register_simple(PLATFORM_NAME,
+						    PLATFORM_DEVID_NONE,
+						    NULL, 0);
+	if (IS_ERR(pf_device)) {
+		ret = PTR_ERR(pf_device);
+		pf_device = NULL;
+		pr_err("unable to register platform device\n");
+		goto out_platform_registered;
+	}
+
+	ret = sysfs_create_group(&pf_device->dev.kobj, &dev_attribute_group);
+	if (ret)
+		goto out_platform_device;
+
+	if (!led_classdev_register(&pf_device->dev, &kbd_backlight))
+		inited |= INIT_KBD_LED;
+
+	if (!led_classdev_register(&pf_device->dev, &tpad_led))
+		inited |= INIT_TPAD_LED;
+
+	wmi_input_setup();
+
+	return 0;
+
+out_platform_device:
+	platform_device_unregister(pf_device);
+out_platform_registered:
+	platform_driver_unregister(&pf_driver);
+	return ret;
+}
+
+static int acpi_remove(struct acpi_device *device)
+{
+	sysfs_remove_group(&pf_device->dev.kobj, &dev_attribute_group);
+	if (inited & INIT_KBD_LED)
+		led_classdev_unregister(&kbd_backlight);
+
+	if (inited & INIT_TPAD_LED)
+		led_classdev_unregister(&tpad_led);
+
+	wmi_input_destroy();
+	platform_device_unregister(pf_device);
+	pf_device = NULL;
+	platform_driver_unregister(&pf_driver);
+
+	return 0;
+}
+
+static const struct acpi_device_id device_ids[] = {
+	{"LGEX0815", 0},
+	{"", 0}
+};
+MODULE_DEVICE_TABLE(acpi, device_ids);
+
+static struct acpi_driver acpi_driver = {
+	.name = "LG Gram Laptop Support",
+	.class = "lg-laptop",
+	.ids = device_ids,
+	.ops = {
+		.add = acpi_add,
+		.remove = acpi_remove,
+		.notify = acpi_notify,
+		},
+	.owner = THIS_MODULE,
+};
+
+static int __init acpi_init(void)
+{
+	int result;
+
+	result = acpi_bus_register_driver(&acpi_driver);
+	if (result < 0) {
+		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error registering driver\n"));
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static void __exit acpi_exit(void)
+{
+	acpi_bus_unregister_driver(&acpi_driver);
+}
+
+module_init(acpi_init);
+module_exit(acpi_exit);