1 files changed, 323 insertions, 504 deletions

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 5c27b4aa9690..1920e115da89 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -23,17 +23,15 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
-#include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/rwsem.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/types.h>
-#include <linux/uaccess.h>
 #include <linux/uuid.h>
 #include <linux/wmi.h>
 #include <linux/fs.h>
-#include <uapi/linux/wmi.h>
 
 MODULE_AUTHOR("Carlos Corbacho");
 MODULE_DESCRIPTION("ACPI-WMI Mapping Driver");
@@ -59,19 +57,19 @@ static_assert(__alignof__(struct guid_block) == 1);
 
 enum {	/* wmi_block flags */
 	WMI_READ_TAKES_NO_ARGS,
-	WMI_PROBED,
+	WMI_GUID_DUPLICATED,
+	WMI_NO_EVENT_DATA,
 };
 
 struct wmi_block {
 	struct wmi_device dev;
 	struct list_head list;
 	struct guid_block gblock;
-	struct miscdevice char_dev;
-	struct mutex char_mutex;
 	struct acpi_device *acpi_device;
+	struct rw_semaphore notify_lock;	/* Protects notify callback add/remove */
 	wmi_notify_handler handler;
 	void *handler_data;
-	u64 req_buf_size;
+	bool driver_ready;
 	unsigned long flags;
 };
 
@@ -85,16 +83,6 @@ struct wmi_block {
 #define ACPI_WMI_STRING      BIT(2)	/* GUID takes & returns a string */
 #define ACPI_WMI_EVENT       BIT(3)	/* GUID is an event */
 
-static bool debug_event;
-module_param(debug_event, bool, 0444);
-MODULE_PARM_DESC(debug_event,
-		 "Log WMI Events [0/1]");
-
-static bool debug_dump_wdg;
-module_param(debug_dump_wdg, bool, 0444);
-MODULE_PARM_DESC(debug_dump_wdg,
-		 "Dump available WMI interfaces [0/1]");
-
 static const struct acpi_device_id wmi_device_ids[] = {
 	{"PNP0C14", 0},
 	{"pnp0c14", 0},
@@ -102,13 +90,6 @@ static const struct acpi_device_id wmi_device_ids[] = {
 };
 MODULE_DEVICE_TABLE(acpi, wmi_device_ids);
 
-/* allow duplicate GUIDs as these device drivers use struct wmi_driver */
-static const char * const allow_duplicates[] = {
-	"05901221-D566-11D1-B2F0-00A0C9062910",	/* wmi-bmof */
-	"8A42EA14-4F2A-FD45-6422-0087F7A7E608",	/* dell-wmi-ddv */
-	NULL
-};
-
 #define dev_to_wblock(__dev)	container_of_const(__dev, struct wmi_block, dev.dev)
 #define dev_to_wdev(__dev)	container_of_const(__dev, struct wmi_device, dev)
 
@@ -143,30 +124,6 @@ static const void *find_guid_context(struct wmi_block *wblock,
 	return NULL;
 }
 
-static int get_subobj_info(acpi_handle handle, const char *pathname,
-			   struct acpi_device_info **info)
-{
-	struct acpi_device_info *dummy_info, **info_ptr;
-	acpi_handle subobj_handle;
-	acpi_status status;
-
-	status = acpi_get_handle(handle, (char *)pathname, &subobj_handle);
-	if (status == AE_NOT_FOUND)
-		return -ENOENT;
-	else if (ACPI_FAILURE(status))
-		return -EIO;
-
-	info_ptr = info ? info : &dummy_info;
-	status = acpi_get_object_info(subobj_handle, info_ptr);
-	if (ACPI_FAILURE(status))
-		return -EIO;
-
-	if (!info)
-		kfree(dummy_info);
-
-	return 0;
-}
-
 static acpi_status wmi_method_enable(struct wmi_block *wblock, bool enable)
 {
 	struct guid_block *block;
@@ -230,13 +187,36 @@ static int wmidev_match_guid(struct device *dev, const void *data)
 	struct wmi_block *wblock = dev_to_wblock(dev);
 	const guid_t *guid = data;
 
+	/* Legacy GUID-based functions are restricted to only see
+	 * a single WMI device for each GUID.
+	 */
+	if (test_bit(WMI_GUID_DUPLICATED, &wblock->flags))
+		return 0;
+
 	if (guid_equal(guid, &wblock->gblock.guid))
 		return 1;
 
 	return 0;
 }
 
-static struct bus_type wmi_bus_type;
+static int wmidev_match_notify_id(struct device *dev, const void *data)
+{
+	struct wmi_block *wblock = dev_to_wblock(dev);
+	const u32 *notify_id = data;
+
+	/* Legacy GUID-based functions are restricted to only see
+	 * a single WMI device for each GUID.
+	 */
+	if (test_bit(WMI_GUID_DUPLICATED, &wblock->flags))
+		return 0;
+
+	if (wblock->gblock.flags & ACPI_WMI_EVENT && wblock->gblock.notify_id == *notify_id)
+		return 1;
+
+	return 0;
+}
+
+static const struct bus_type wmi_bus_type;
 
 static struct wmi_device *wmi_find_device_by_guid(const char *guid_string)
 {
@@ -255,6 +235,17 @@ static struct wmi_device *wmi_find_device_by_guid(const char *guid_string)
 	return dev_to_wdev(dev);
 }
 
+static struct wmi_device *wmi_find_event_by_notify_id(const u32 notify_id)
+{
+	struct device *dev;
+
+	dev = bus_find_device(&wmi_bus_type, NULL, &notify_id, wmidev_match_notify_id);
+	if (!dev)
+		return ERR_PTR(-ENODEV);
+
+	return to_wmi_device(dev);
+}
+
 static void wmi_device_put(struct wmi_device *wdev)
 {
 	put_device(&wdev->dev);
@@ -265,26 +256,6 @@ static void wmi_device_put(struct wmi_device *wdev)
  */
 
 /**
- * set_required_buffer_size - Sets the buffer size needed for performing IOCTL
- * @wdev: A wmi bus device from a driver
- * @length: Required buffer size
- *
- * Allocates memory needed for buffer, stores the buffer size in that memory.
- *
- * Return: 0 on success or a negative error code for failure.
- */
-int set_required_buffer_size(struct wmi_device *wdev, u64 length)
-{
-	struct wmi_block *wblock;
-
-	wblock = container_of(wdev, struct wmi_block, dev);
-	wblock->req_buf_size = length;
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(set_required_buffer_size);
-
-/**
  * wmi_instance_count - Get number of WMI object instances
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
  *
@@ -329,7 +300,7 @@ EXPORT_SYMBOL_GPL(wmidev_instance_count);
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
  * @instance: Instance index
  * @method_id: Method ID to call
- * @in: Buffer containing input for the method call
+ * @in: Mandatory buffer containing input for the method call
  * @out: Empty buffer to return the method results
  *
  * Call an ACPI-WMI method, the caller must free @out.
@@ -359,7 +330,7 @@ EXPORT_SYMBOL_GPL(wmi_evaluate_method);
  * @wdev: A wmi bus device from a driver
  * @instance: Instance index
  * @method_id: Method ID to call
- * @in: Buffer containing input for the method call
+ * @in: Mandatory buffer containing input for the method call
  * @out: Empty buffer to return the method results
  *
  * Call an ACPI-WMI method, the caller must free @out.
@@ -380,26 +351,25 @@ acpi_status wmidev_evaluate_method(struct wmi_device *wdev, u8 instance, u32 met
 	block = &wblock->gblock;
 	handle = wblock->acpi_device->handle;
 
+	if (!in)
+		return AE_BAD_DATA;
+
 	if (!(block->flags & ACPI_WMI_METHOD))
 		return AE_BAD_DATA;
 
 	if (block->instance_count <= instance)
 		return AE_BAD_PARAMETER;
 
-	input.count = 2;
+	input.count = 3;
 	input.pointer = params;
+
 	params[0].type = ACPI_TYPE_INTEGER;
 	params[0].integer.value = instance;
 	params[1].type = ACPI_TYPE_INTEGER;
 	params[1].integer.value = method_id;
-
-	if (in) {
-		input.count = 3;
-
-		params[2].type = get_param_acpi_type(wblock);
-		params[2].buffer.length = in->length;
-		params[2].buffer.pointer = in->pointer;
-	}
+	params[2].type = get_param_acpi_type(wblock);
+	params[2].buffer.length = in->length;
+	params[2].buffer.pointer = in->pointer;
 
 	get_acpi_method_name(wblock, 'M', method);
 
@@ -536,41 +506,50 @@ EXPORT_SYMBOL_GPL(wmidev_block_query);
  *
  * Return: acpi_status signaling success or error.
  */
-acpi_status wmi_set_block(const char *guid_string, u8 instance,
-			  const struct acpi_buffer *in)
+acpi_status wmi_set_block(const char *guid_string, u8 instance, const struct acpi_buffer *in)
 {
-	struct wmi_block *wblock;
-	struct guid_block *block;
 	struct wmi_device *wdev;
-	acpi_handle handle;
-	struct acpi_object_list input;
-	union acpi_object params[2];
-	char method[WMI_ACPI_METHOD_NAME_SIZE];
 	acpi_status status;
 
-	if (!in)
-		return AE_BAD_DATA;
-
 	wdev = wmi_find_device_by_guid(guid_string);
 	if (IS_ERR(wdev))
 		return AE_ERROR;
 
-	wblock = container_of(wdev, struct wmi_block, dev);
-	block = &wblock->gblock;
-	handle = wblock->acpi_device->handle;
+	status =  wmidev_block_set(wdev, instance, in);
+	wmi_device_put(wdev);
 
-	if (block->instance_count <= instance) {
-		status = AE_BAD_PARAMETER;
+	return status;
+}
+EXPORT_SYMBOL_GPL(wmi_set_block);
 
-		goto err_wdev_put;
-	}
+/**
+ * wmidev_block_set - Write to a WMI block
+ * @wdev: A wmi bus device from a driver
+ * @instance: Instance index
+ * @in: Buffer containing new values for the data block
+ *
+ * Write contents of the input buffer to an ACPI-WMI data block.
+ *
+ * Return: acpi_status signaling success or error.
+ */
+acpi_status wmidev_block_set(struct wmi_device *wdev, u8 instance, const struct acpi_buffer *in)
+{
+	struct wmi_block *wblock = container_of(wdev, struct wmi_block, dev);
+	acpi_handle handle = wblock->acpi_device->handle;
+	struct guid_block *block = &wblock->gblock;
+	char method[WMI_ACPI_METHOD_NAME_SIZE];
+	struct acpi_object_list input;
+	union acpi_object params[2];
 
-	/* Check GUID is a data block */
-	if (block->flags & (ACPI_WMI_EVENT | ACPI_WMI_METHOD)) {
-		status = AE_ERROR;
+	if (!in)
+		return AE_BAD_DATA;
 
-		goto err_wdev_put;
-	}
+	if (block->instance_count <= instance)
+		return AE_BAD_PARAMETER;
+
+	/* Check GUID is a data block */
+	if (block->flags & (ACPI_WMI_EVENT | ACPI_WMI_METHOD))
+		return AE_ERROR;
 
 	input.count = 2;
 	input.pointer = params;
@@ -582,73 +561,9 @@ acpi_status wmi_set_block(const char *guid_string, u8 instance,
 
 	get_acpi_method_name(wblock, 'S', method);
 
-	status = acpi_evaluate_object(handle, method, &input, NULL);
-
-err_wdev_put:
-	wmi_device_put(wdev);
-
-	return status;
-}
-EXPORT_SYMBOL_GPL(wmi_set_block);
-
-static void wmi_dump_wdg(const struct guid_block *g)
-{
-	pr_info("%pUL:\n", &g->guid);
-	if (g->flags & ACPI_WMI_EVENT)
-		pr_info("\tnotify_id: 0x%02X\n", g->notify_id);
-	else
-		pr_info("\tobject_id: %2pE\n", g->object_id);
-	pr_info("\tinstance_count: %d\n", g->instance_count);
-	pr_info("\tflags: %#x", g->flags);
-	if (g->flags) {
-		if (g->flags & ACPI_WMI_EXPENSIVE)
-			pr_cont(" ACPI_WMI_EXPENSIVE");
-		if (g->flags & ACPI_WMI_METHOD)
-			pr_cont(" ACPI_WMI_METHOD");
-		if (g->flags & ACPI_WMI_STRING)
-			pr_cont(" ACPI_WMI_STRING");
-		if (g->flags & ACPI_WMI_EVENT)
-			pr_cont(" ACPI_WMI_EVENT");
-	}
-	pr_cont("\n");
-
-}
-
-static void wmi_notify_debug(u32 value, void *context)
-{
-	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
-	union acpi_object *obj;
-	acpi_status status;
-
-	status = wmi_get_event_data(value, &response);
-	if (status != AE_OK) {
-		pr_info("bad event status 0x%x\n", status);
-		return;
-	}
-
-	obj = response.pointer;
-	if (!obj)
-		return;
-
-	pr_info("DEBUG: event 0x%02X ", value);
-	switch (obj->type) {
-	case ACPI_TYPE_BUFFER:
-		pr_cont("BUFFER_TYPE - length %u\n", obj->buffer.length);
-		break;
-	case ACPI_TYPE_STRING:
-		pr_cont("STRING_TYPE - %s\n", obj->string.pointer);
-		break;
-	case ACPI_TYPE_INTEGER:
-		pr_cont("INTEGER_TYPE - %llu\n", obj->integer.value);
-		break;
-	case ACPI_TYPE_PACKAGE:
-		pr_cont("PACKAGE_TYPE - %u elements\n", obj->package.count);
-		break;
-	default:
-		pr_cont("object type 0x%X\n", obj->type);
-	}
-	kfree(obj);
+	return acpi_evaluate_object(handle, method, &input, NULL);
 }
+EXPORT_SYMBOL_GPL(wmidev_block_set);
 
 /**
  * wmi_install_notify_handler - Register handler for WMI events (deprecated)
@@ -664,33 +579,31 @@ acpi_status wmi_install_notify_handler(const char *guid,
 				       wmi_notify_handler handler,
 				       void *data)
 {
-	struct wmi_block *block;
-	acpi_status status = AE_NOT_EXIST;
-	guid_t guid_input;
-
-	if (!guid || !handler)
-		return AE_BAD_PARAMETER;
+	struct wmi_block *wblock;
+	struct wmi_device *wdev;
+	acpi_status status;
 
-	if (guid_parse(guid, &guid_input))
-		return AE_BAD_PARAMETER;
+	wdev = wmi_find_device_by_guid(guid);
+	if (IS_ERR(wdev))
+		return AE_ERROR;
 
-	list_for_each_entry(block, &wmi_block_list, list) {
-		acpi_status wmi_status;
+	wblock = container_of(wdev, struct wmi_block, dev);
 
-		if (guid_equal(&block->gblock.guid, &guid_input)) {
-			if (block->handler &&
-			    block->handler != wmi_notify_debug)
-				return AE_ALREADY_ACQUIRED;
+	down_write(&wblock->notify_lock);
+	if (wblock->handler) {
+		status = AE_ALREADY_ACQUIRED;
+	} else {
+		wblock->handler = handler;
+		wblock->handler_data = data;
 
-			block->handler = handler;
-			block->handler_data = data;
+		if (ACPI_FAILURE(wmi_method_enable(wblock, true)))
+			dev_warn(&wblock->dev.dev, "Failed to enable device\n");
 
-			wmi_status = wmi_method_enable(block, true);
-			if ((wmi_status != AE_OK) ||
-			    ((wmi_status == AE_OK) && (status == AE_NOT_EXIST)))
-				status = wmi_status;
-		}
+		status = AE_OK;
 	}
+	up_write(&wblock->notify_lock);
+
+	wmi_device_put(wdev);
 
 	return status;
 }
@@ -706,38 +619,31 @@ EXPORT_SYMBOL_GPL(wmi_install_notify_handler);
  */
 acpi_status wmi_remove_notify_handler(const char *guid)
 {
-	struct wmi_block *block;
-	acpi_status status = AE_NOT_EXIST;
-	guid_t guid_input;
+	struct wmi_block *wblock;
+	struct wmi_device *wdev;
+	acpi_status status;
 
-	if (!guid)
-		return AE_BAD_PARAMETER;
+	wdev = wmi_find_device_by_guid(guid);
+	if (IS_ERR(wdev))
+		return AE_ERROR;
 
-	if (guid_parse(guid, &guid_input))
-		return AE_BAD_PARAMETER;
+	wblock = container_of(wdev, struct wmi_block, dev);
 
-	list_for_each_entry(block, &wmi_block_list, list) {
-		acpi_status wmi_status;
-
-		if (guid_equal(&block->gblock.guid, &guid_input)) {
-			if (!block->handler ||
-			    block->handler == wmi_notify_debug)
-				return AE_NULL_ENTRY;
-
-			if (debug_event) {
-				block->handler = wmi_notify_debug;
-				status = AE_OK;
-			} else {
-				wmi_status = wmi_method_enable(block, false);
-				block->handler = NULL;
-				block->handler_data = NULL;
-				if ((wmi_status != AE_OK) ||
-				    ((wmi_status == AE_OK) &&
-				     (status == AE_NOT_EXIST)))
-					status = wmi_status;
-			}
-		}
+	down_write(&wblock->notify_lock);
+	if (!wblock->handler) {
+		status = AE_NULL_ENTRY;
+	} else {
+		if (ACPI_FAILURE(wmi_method_enable(wblock, false)))
+			dev_warn(&wblock->dev.dev, "Failed to disable device\n");
+
+		wblock->handler = NULL;
+		wblock->handler_data = NULL;
+
+		status = AE_OK;
 	}
+	up_write(&wblock->notify_lock);
+
+	wmi_device_put(wdev);
 
 	return status;
 }
@@ -756,15 +662,19 @@ EXPORT_SYMBOL_GPL(wmi_remove_notify_handler);
 acpi_status wmi_get_event_data(u32 event, struct acpi_buffer *out)
 {
 	struct wmi_block *wblock;
+	struct wmi_device *wdev;
+	acpi_status status;
 
-	list_for_each_entry(wblock, &wmi_block_list, list) {
-		struct guid_block *gblock = &wblock->gblock;
+	wdev = wmi_find_event_by_notify_id(event);
+	if (IS_ERR(wdev))
+		return AE_NOT_FOUND;
 
-		if ((gblock->flags & ACPI_WMI_EVENT) && gblock->notify_id == event)
-			return get_event_data(wblock, out);
-	}
+	wblock = container_of(wdev, struct wmi_block, dev);
+	status = get_event_data(wblock, out);
+
+	wmi_device_put(wdev);
 
-	return AE_NOT_FOUND;
+	return status;
 }
 EXPORT_SYMBOL_GPL(wmi_get_event_data);
 
@@ -956,167 +866,49 @@ static int wmi_dev_match(struct device *dev, struct device_driver *driver)
 
 	return 0;
 }
-static int wmi_char_open(struct inode *inode, struct file *filp)
-{
-	/*
-	 * The miscdevice already stores a pointer to itself
-	 * inside filp->private_data
-	 */
-	struct wmi_block *wblock = container_of(filp->private_data, struct wmi_block, char_dev);
-
-	filp->private_data = wblock;
-
-	return nonseekable_open(inode, filp);
-}
 
-static ssize_t wmi_char_read(struct file *filp, char __user *buffer,
-			     size_t length, loff_t *offset)
-{
-	struct wmi_block *wblock = filp->private_data;
-
-	return simple_read_from_buffer(buffer, length, offset,
-				       &wblock->req_buf_size,
-				       sizeof(wblock->req_buf_size));
-}
-
-static long wmi_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+static int wmi_dev_probe(struct device *dev)
 {
-	struct wmi_ioctl_buffer __user *input =
-		(struct wmi_ioctl_buffer __user *) arg;
-	struct wmi_block *wblock = filp->private_data;
-	struct wmi_ioctl_buffer *buf;
-	struct wmi_driver *wdriver;
-	int ret;
-
-	if (_IOC_TYPE(cmd) != WMI_IOC)
-		return -ENOTTY;
+	struct wmi_block *wblock = dev_to_wblock(dev);
+	struct wmi_driver *wdriver = drv_to_wdrv(dev->driver);
+	int ret = 0;
 
-	/* make sure we're not calling a higher instance than exists*/
-	if (_IOC_NR(cmd) >= wblock->gblock.instance_count)
-		return -EINVAL;
+	/* Some older WMI drivers will break if instantiated multiple times,
+	 * so they are blocked from probing WMI devices with a duplicated GUID.
+	 *
+	 * New WMI drivers should support being instantiated multiple times.
+	 */
+	if (test_bit(WMI_GUID_DUPLICATED, &wblock->flags) && !wdriver->no_singleton) {
+		dev_warn(dev, "Legacy driver %s cannot be instantiated multiple times\n",
+			 dev->driver->name);
 
-	mutex_lock(&wblock->char_mutex);
-	buf = wblock->handler_data;
-	if (get_user(buf->length, &input->length)) {
-		dev_dbg(&wblock->dev.dev, "Read length from user failed\n");
-		ret = -EFAULT;
-		goto out_ioctl;
-	}
-	/* if it's too small, abort */
-	if (buf->length < wblock->req_buf_size) {
-		dev_err(&wblock->dev.dev,
-			"Buffer %lld too small, need at least %lld\n",
-			buf->length, wblock->req_buf_size);
-		ret = -EINVAL;
-		goto out_ioctl;
-	}
-	/* if it's too big, warn, driver will only use what is needed */
-	if (buf->length > wblock->req_buf_size)
-		dev_warn(&wblock->dev.dev,
-			"Buffer %lld is bigger than required %lld\n",
-			buf->length, wblock->req_buf_size);
-
-	/* copy the structure from userspace */
-	if (copy_from_user(buf, input, wblock->req_buf_size)) {
-		dev_dbg(&wblock->dev.dev, "Copy %llu from user failed\n",
-			wblock->req_buf_size);
-		ret = -EFAULT;
-		goto out_ioctl;
+		return -ENODEV;
 	}
 
-	/* let the driver do any filtering and do the call */
-	wdriver = drv_to_wdrv(wblock->dev.dev.driver);
-	if (!try_module_get(wdriver->driver.owner)) {
-		ret = -EBUSY;
-		goto out_ioctl;
-	}
-	ret = wdriver->filter_callback(&wblock->dev, cmd, buf);
-	module_put(wdriver->driver.owner);
-	if (ret)
-		goto out_ioctl;
-
-	/* return the result (only up to our internal buffer size) */
-	if (copy_to_user(input, buf, wblock->req_buf_size)) {
-		dev_dbg(&wblock->dev.dev, "Copy %llu to user failed\n",
-			wblock->req_buf_size);
-		ret = -EFAULT;
+	if (wdriver->notify) {
+		if (test_bit(WMI_NO_EVENT_DATA, &wblock->flags) && !wdriver->no_notify_data)
+			return -ENODEV;
 	}
 
-out_ioctl:
-	mutex_unlock(&wblock->char_mutex);
-	return ret;
-}
-
-static const struct file_operations wmi_fops = {
-	.owner		= THIS_MODULE,
-	.read		= wmi_char_read,
-	.open		= wmi_char_open,
-	.unlocked_ioctl	= wmi_ioctl,
-	.compat_ioctl	= compat_ptr_ioctl,
-};
-
-static int wmi_dev_probe(struct device *dev)
-{
-	struct wmi_block *wblock = dev_to_wblock(dev);
-	struct wmi_driver *wdriver = drv_to_wdrv(dev->driver);
-	int ret = 0;
-	char *buf;
-
 	if (ACPI_FAILURE(wmi_method_enable(wblock, true)))
 		dev_warn(dev, "failed to enable device -- probing anyway\n");
 
 	if (wdriver->probe) {
 		ret = wdriver->probe(dev_to_wdev(dev),
 				find_guid_context(wblock, wdriver));
-		if (ret != 0)
-			goto probe_failure;
-	}
-
-	/* driver wants a character device made */
-	if (wdriver->filter_callback) {
-		/* check that required buffer size declared by driver or MOF */
-		if (!wblock->req_buf_size) {
-			dev_err(&wblock->dev.dev,
-				"Required buffer size not set\n");
-			ret = -EINVAL;
-			goto probe_failure;
-		}
-
-		wblock->handler_data = kmalloc(wblock->req_buf_size,
-					       GFP_KERNEL);
-		if (!wblock->handler_data) {
-			ret = -ENOMEM;
-			goto probe_failure;
-		}
-
-		buf = kasprintf(GFP_KERNEL, "wmi/%s", wdriver->driver.name);
-		if (!buf) {
-			ret = -ENOMEM;
-			goto probe_string_failure;
-		}
-		wblock->char_dev.minor = MISC_DYNAMIC_MINOR;
-		wblock->char_dev.name = buf;
-		wblock->char_dev.fops = &wmi_fops;
-		wblock->char_dev.mode = 0444;
-		ret = misc_register(&wblock->char_dev);
 		if (ret) {
-			dev_warn(dev, "failed to register char dev: %d\n", ret);
-			ret = -ENOMEM;
-			goto probe_misc_failure;
+			if (ACPI_FAILURE(wmi_method_enable(wblock, false)))
+				dev_warn(dev, "Failed to disable device\n");
+
+			return ret;
 		}
 	}
 
-	set_bit(WMI_PROBED, &wblock->flags);
-	return 0;
+	down_write(&wblock->notify_lock);
+	wblock->driver_ready = true;
+	up_write(&wblock->notify_lock);
 
-probe_misc_failure:
-	kfree(buf);
-probe_string_failure:
-	kfree(wblock->handler_data);
-probe_failure:
-	if (ACPI_FAILURE(wmi_method_enable(wblock, false)))
-		dev_warn(dev, "failed to disable device\n");
-	return ret;
+	return 0;
 }
 
 static void wmi_dev_remove(struct device *dev)
@@ -1124,13 +916,9 @@ static void wmi_dev_remove(struct device *dev)
 	struct wmi_block *wblock = dev_to_wblock(dev);
 	struct wmi_driver *wdriver = drv_to_wdrv(dev->driver);
 
-	clear_bit(WMI_PROBED, &wblock->flags);
-
-	if (wdriver->filter_callback) {
-		misc_deregister(&wblock->char_dev);
-		kfree(wblock->char_dev.name);
-		kfree(wblock->handler_data);
-	}
+	down_write(&wblock->notify_lock);
+	wblock->driver_ready = false;
+	up_write(&wblock->notify_lock);
 
 	if (wdriver->remove)
 		wdriver->remove(dev_to_wdev(dev));
@@ -1143,7 +931,7 @@ static struct class wmi_bus_class = {
 	.name = "wmi_bus",
 };
 
-static struct bus_type wmi_bus_type = {
+static const struct bus_type wmi_bus_type = {
 	.name = "wmi",
 	.dev_groups = wmi_groups,
 	.match = wmi_dev_match,
@@ -1191,9 +979,10 @@ static int wmi_create_device(struct device *wmi_bus_dev,
 			     struct wmi_block *wblock,
 			     struct acpi_device *device)
 {
-	struct acpi_device_info *info;
 	char method[WMI_ACPI_METHOD_NAME_SIZE];
-	int result;
+	struct acpi_device_info *info;
+	acpi_handle method_handle;
+	acpi_status status;
 	uint count;
 
 	if (wblock->gblock.flags & ACPI_WMI_EVENT) {
@@ -1202,8 +991,16 @@ static int wmi_create_device(struct device *wmi_bus_dev,
 	}
 
 	if (wblock->gblock.flags & ACPI_WMI_METHOD) {
+		get_acpi_method_name(wblock, 'M', method);
+		if (!acpi_has_method(device->handle, method)) {
+			dev_warn(wmi_bus_dev,
+				 FW_BUG "%s method block execution control method not found\n",
+				 method);
+
+			return -ENXIO;
+		}
+
 		wblock->dev.dev.type = &wmi_type_method;
-		mutex_init(&wblock->char_mutex);
 		goto out_init;
 	}
 
@@ -1213,15 +1010,19 @@ static int wmi_create_device(struct device *wmi_bus_dev,
 	 * we ignore this data block.
 	 */
 	get_acpi_method_name(wblock, 'Q', method);
-	result = get_subobj_info(device->handle, method, &info);
-
-	if (result) {
+	status = acpi_get_handle(device->handle, method, &method_handle);
+	if (ACPI_FAILURE(status)) {
 		dev_warn(wmi_bus_dev,
-			 "%s data block query control method not found\n",
+			 FW_BUG "%s data block query control method not found\n",
 			 method);
-		return result;
+
+		return -ENXIO;
 	}
 
+	status = acpi_get_object_info(method_handle, &info);
+	if (ACPI_FAILURE(status))
+		return -EIO;
+
 	wblock->dev.dev.type = &wmi_type_data;
 
 	/*
@@ -1240,20 +1041,22 @@ static int wmi_create_device(struct device *wmi_bus_dev,
 	kfree(info);
 
 	get_acpi_method_name(wblock, 'S', method);
-	result = get_subobj_info(device->handle, method, NULL);
-
-	if (result == 0)
+	if (acpi_has_method(device->handle, method))
 		wblock->dev.setable = true;
 
  out_init:
+	init_rwsem(&wblock->notify_lock);
+	wblock->driver_ready = false;
 	wblock->dev.dev.bus = &wmi_bus_type;
 	wblock->dev.dev.parent = wmi_bus_dev;
 
 	count = guid_count(&wblock->gblock.guid);
-	if (count)
+	if (count) {
 		dev_set_name(&wblock->dev.dev, "%pUL-%d", &wblock->gblock.guid, count);
-	else
+		set_bit(WMI_GUID_DUPLICATED, &wblock->flags);
+	} else {
 		dev_set_name(&wblock->dev.dev, "%pUL", &wblock->gblock.guid);
+	}
 
 	device_initialize(&wblock->dev.dev);
 
@@ -1280,32 +1083,6 @@ static int wmi_add_device(struct platform_device *pdev, struct wmi_device *wdev)
 	return device_add(&wdev->dev);
 }
 
-static bool guid_already_parsed_for_legacy(struct acpi_device *device, const guid_t *guid)
-{
-	struct wmi_block *wblock;
-
-	list_for_each_entry(wblock, &wmi_block_list, list) {
-		/* skip warning and register if we know the driver will use struct wmi_driver */
-		for (int i = 0; allow_duplicates[i] != NULL; i++) {
-			if (guid_parse_and_compare(allow_duplicates[i], guid))
-				return false;
-		}
-		if (guid_equal(&wblock->gblock.guid, guid)) {
-			/*
-			 * Because we historically didn't track the relationship
-			 * between GUIDs and ACPI nodes, we don't know whether
-			 * we need to suppress GUIDs that are unique on a
-			 * given node but duplicated across nodes.
-			 */
-			dev_warn(&device->dev, "duplicate WMI GUID %pUL (first instance was on %s)\n",
-				 guid, dev_name(&wblock->acpi_device->dev));
-			return true;
-		}
-	}
-
-	return false;
-}
-
 /*
  * Parse the _WDG method for the GUID data blocks
  */
@@ -1314,6 +1091,7 @@ static int parse_wdg(struct device *wmi_bus_dev, struct platform_device *pdev)
 	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
 	struct acpi_buffer out = {ACPI_ALLOCATE_BUFFER, NULL};
 	const struct guid_block *gblock;
+	bool event_data_available;
 	struct wmi_block *wblock;
 	union acpi_object *obj;
 	acpi_status status;
@@ -1333,24 +1111,24 @@ static int parse_wdg(struct device *wmi_bus_dev, struct platform_device *pdev)
 		return -ENXIO;
 	}
 
+	event_data_available = acpi_has_method(device->handle, "_WED");
 	gblock = (const struct guid_block *)obj->buffer.pointer;
 	total = obj->buffer.length / sizeof(struct guid_block);
 
 	for (i = 0; i < total; i++) {
-		if (debug_dump_wdg)
-			wmi_dump_wdg(&gblock[i]);
-
-		if (guid_already_parsed_for_legacy(device, &gblock[i].guid))
+		if (!gblock[i].instance_count) {
+			dev_info(wmi_bus_dev, FW_INFO "%pUL has zero instances\n", &gblock[i].guid);
 			continue;
+		}
 
 		wblock = kzalloc(sizeof(*wblock), GFP_KERNEL);
-		if (!wblock) {
-			dev_err(wmi_bus_dev, "Failed to allocate %pUL\n", &gblock[i].guid);
+		if (!wblock)
 			continue;
-		}
 
 		wblock->acpi_device = device;
 		wblock->gblock = gblock[i];
+		if (gblock[i].flags & ACPI_WMI_EVENT && !event_data_available)
+			set_bit(WMI_NO_EVENT_DATA, &wblock->flags);
 
 		retval = wmi_create_device(wmi_bus_dev, wblock, device);
 		if (retval) {
@@ -1360,17 +1138,10 @@ static int parse_wdg(struct device *wmi_bus_dev, struct platform_device *pdev)
 
 		list_add_tail(&wblock->list, &wmi_block_list);
 
-		if (debug_event) {
-			wblock->handler = wmi_notify_debug;
-			wmi_method_enable(wblock, true);
-		}
-
 		retval = wmi_add_device(pdev, &wblock->dev);
 		if (retval) {
 			dev_err(wmi_bus_dev, "failed to register %pUL\n",
 				&wblock->gblock.guid);
-			if (debug_event)
-				wmi_method_enable(wblock, false);
 
 			list_del(&wblock->list);
 			put_device(&wblock->dev.dev);
@@ -1391,7 +1162,7 @@ acpi_wmi_ec_space_handler(u32 function, acpi_physical_address address,
 			  u32 bits, u64 *value,
 			  void *handler_context, void *region_context)
 {
-	int result = 0, i = 0;
+	int result = 0;
 	u8 temp = 0;
 
 	if ((address > 0xFF) || !value)
@@ -1405,9 +1176,9 @@ acpi_wmi_ec_space_handler(u32 function, acpi_physical_address address,
 
 	if (function == ACPI_READ) {
 		result = ec_read(address, &temp);
-		(*value) |= ((u64)temp) << i;
+		*value = temp;
 	} else {
-		temp = 0xff & ((*value) >> i);
+		temp = 0xff & *value;
 		result = ec_write(address, temp);
 	}
 
@@ -1423,55 +1194,94 @@ acpi_wmi_ec_space_handler(u32 function, acpi_physical_address address,
 	}
 }
 
-static void acpi_wmi_notify_handler(acpi_handle handle, u32 event,
-				    void *context)
+static int wmi_get_notify_data(struct wmi_block *wblock, union acpi_object **obj)
 {
-	struct wmi_block *wblock = NULL, *iter;
+	struct acpi_buffer data = { ACPI_ALLOCATE_BUFFER, NULL };
+	acpi_status status;
 
-	list_for_each_entry(iter, &wmi_block_list, list) {
-		struct guid_block *block = &iter->gblock;
+	if (test_bit(WMI_NO_EVENT_DATA, &wblock->flags)) {
+		*obj = NULL;
+		return 0;
+	}
 
-		if (iter->acpi_device->handle == handle &&
-		    (block->flags & ACPI_WMI_EVENT) &&
-		    (block->notify_id == event)) {
-			wblock = iter;
-			break;
-		}
+	status = get_event_data(wblock, &data);
+	if (ACPI_FAILURE(status)) {
+		dev_warn(&wblock->dev.dev, "Failed to get event data\n");
+		return -EIO;
 	}
 
-	if (!wblock)
+	*obj = data.pointer;
+
+	return 0;
+}
+
+static void wmi_notify_driver(struct wmi_block *wblock, union acpi_object *obj)
+{
+	struct wmi_driver *driver = drv_to_wdrv(wblock->dev.dev.driver);
+
+	if (!obj && !driver->no_notify_data) {
+		dev_warn(&wblock->dev.dev, "Event contains no event data\n");
 		return;
+	}
 
-	/* If a driver is bound, then notify the driver. */
-	if (test_bit(WMI_PROBED, &wblock->flags) && wblock->dev.dev.driver) {
-		struct wmi_driver *driver = drv_to_wdrv(wblock->dev.dev.driver);
-		struct acpi_buffer evdata = { ACPI_ALLOCATE_BUFFER, NULL };
-		acpi_status status;
-
-		if (!driver->no_notify_data) {
-			status = get_event_data(wblock, &evdata);
-			if (ACPI_FAILURE(status)) {
-				dev_warn(&wblock->dev.dev, "failed to get event data\n");
-				return;
-			}
-		}
+	if (driver->notify)
+		driver->notify(&wblock->dev, obj);
+}
 
-		if (driver->notify)
-			driver->notify(&wblock->dev, evdata.pointer);
+static int wmi_notify_device(struct device *dev, void *data)
+{
+	struct wmi_block *wblock = dev_to_wblock(dev);
+	union acpi_object *obj;
+	u32 *event = data;
+	int ret;
+
+	if (!(wblock->gblock.flags & ACPI_WMI_EVENT && wblock->gblock.notify_id == *event))
+		return 0;
+
+	down_read(&wblock->notify_lock);
+	/* The WMI driver notify handler conflicts with the legacy WMI handler.
+	 * Because of this the WMI driver notify handler takes precedence.
+	 */
+	if (wblock->dev.dev.driver && wblock->driver_ready) {
+		ret = wmi_get_notify_data(wblock, &obj);
+		if (ret >= 0) {
+			wmi_notify_driver(wblock, obj);
+			kfree(obj);
+		}
+	} else {
+		if (wblock->handler) {
+			wblock->handler(*event, wblock->handler_data);
+		} else {
+			/* The ACPI WMI specification says that _WED should be
+			 * evaluated every time an notification is received, even
+			 * if no consumers are present.
+			 *
+			 * Some firmware implementations actually depend on this
+			 * by using a queue for events which will fill up if the
+			 * WMI driver core stops evaluating _WED due to missing
+			 * WMI event consumers.
+			 *
+			 * Because of this we need this seemingly useless call to
+			 * wmi_get_notify_data() which in turn evaluates _WED.
+			 */
+			ret = wmi_get_notify_data(wblock, &obj);
+			if (ret >= 0)
+				kfree(obj);
+		}
 
-		kfree(evdata.pointer);
-	} else if (wblock->handler) {
-		/* Legacy handler */
-		wblock->handler(event, wblock->handler_data);
 	}
+	up_read(&wblock->notify_lock);
+
+	acpi_bus_generate_netlink_event("wmi", acpi_dev_name(wblock->acpi_device), *event, 0);
 
-	if (debug_event)
-		pr_info("DEBUG: GUID %pUL event 0x%02X\n", &wblock->gblock.guid, event);
+	return -EBUSY;
+}
+
+static void acpi_wmi_notify_handler(acpi_handle handle, u32 event, void *context)
+{
+	struct device *wmi_bus_dev = context;
 
-	acpi_bus_generate_netlink_event(
-		wblock->acpi_device->pnp.device_class,
-		dev_name(&wblock->dev.dev),
-		event, 0);
+	device_for_each_child(wmi_bus_dev, &event, wmi_notify_device);
 }
 
 static int wmi_remove_device(struct device *dev, void *data)
@@ -1486,16 +1296,31 @@ static int wmi_remove_device(struct device *dev, void *data)
 
 static void acpi_wmi_remove(struct platform_device *device)
 {
-	struct acpi_device *acpi_device = ACPI_COMPANION(&device->dev);
 	struct device *wmi_bus_device = dev_get_drvdata(&device->dev);
 
-	acpi_remove_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY,
-				   acpi_wmi_notify_handler);
-	acpi_remove_address_space_handler(acpi_device->handle,
-				ACPI_ADR_SPACE_EC, &acpi_wmi_ec_space_handler);
-
 	device_for_each_child_reverse(wmi_bus_device, NULL, wmi_remove_device);
-	device_unregister(wmi_bus_device);
+}
+
+static void acpi_wmi_remove_notify_handler(void *data)
+{
+	struct acpi_device *acpi_device = data;
+
+	acpi_remove_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY, acpi_wmi_notify_handler);
+}
+
+static void acpi_wmi_remove_address_space_handler(void *data)
+{
+	struct acpi_device *acpi_device = data;
+
+	acpi_remove_address_space_handler(acpi_device->handle, ACPI_ADR_SPACE_EC,
+					  &acpi_wmi_ec_space_handler);
+}
+
+static void acpi_wmi_remove_bus_device(void *data)
+{
+	struct device *wmi_bus_dev = data;
+
+	device_unregister(wmi_bus_dev);
 }
 
 static int acpi_wmi_probe(struct platform_device *device)
@@ -1511,6 +1336,17 @@ static int acpi_wmi_probe(struct platform_device *device)
 		return -ENODEV;
 	}
 
+	wmi_bus_dev = device_create(&wmi_bus_class, &device->dev, MKDEV(0, 0), NULL, "wmi_bus-%s",
+				    dev_name(&device->dev));
+	if (IS_ERR(wmi_bus_dev))
+		return PTR_ERR(wmi_bus_dev);
+
+	error = devm_add_action_or_reset(&device->dev, acpi_wmi_remove_bus_device, wmi_bus_dev);
+	if (error < 0)
+		return error;
+
+	dev_set_drvdata(&device->dev, wmi_bus_dev);
+
 	status = acpi_install_address_space_handler(acpi_device->handle,
 						    ACPI_ADR_SPACE_EC,
 						    &acpi_wmi_ec_space_handler,
@@ -1519,46 +1355,29 @@ static int acpi_wmi_probe(struct platform_device *device)
 		dev_err(&device->dev, "Error installing EC region handler\n");
 		return -ENODEV;
 	}
+	error = devm_add_action_or_reset(&device->dev, acpi_wmi_remove_address_space_handler,
+					 acpi_device);
+	if (error < 0)
+		return error;
 
-	status = acpi_install_notify_handler(acpi_device->handle,
-					     ACPI_ALL_NOTIFY,
-					     acpi_wmi_notify_handler,
-					     NULL);
+	status = acpi_install_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY,
+					     acpi_wmi_notify_handler, wmi_bus_dev);
 	if (ACPI_FAILURE(status)) {
 		dev_err(&device->dev, "Error installing notify handler\n");
-		error = -ENODEV;
-		goto err_remove_ec_handler;
-	}
-
-	wmi_bus_dev = device_create(&wmi_bus_class, &device->dev, MKDEV(0, 0),
-				    NULL, "wmi_bus-%s", dev_name(&device->dev));
-	if (IS_ERR(wmi_bus_dev)) {
-		error = PTR_ERR(wmi_bus_dev);
-		goto err_remove_notify_handler;
+		return -ENODEV;
 	}
-	dev_set_drvdata(&device->dev, wmi_bus_dev);
+	error = devm_add_action_or_reset(&device->dev, acpi_wmi_remove_notify_handler,
+					 acpi_device);
+	if (error < 0)
+		return error;
 
 	error = parse_wdg(wmi_bus_dev, device);
 	if (error) {
-		pr_err("Failed to parse WDG method\n");
-		goto err_remove_busdev;
+		dev_err(&device->dev, "Failed to parse _WDG method\n");
+		return error;
 	}
 
 	return 0;
-
-err_remove_busdev:
-	device_unregister(wmi_bus_dev);
-
-err_remove_notify_handler:
-	acpi_remove_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY,
-				   acpi_wmi_notify_handler);
-
-err_remove_ec_handler:
-	acpi_remove_address_space_handler(acpi_device->handle,
-					  ACPI_ADR_SPACE_EC,
-					  &acpi_wmi_ec_space_handler);
-
-	return error;
 }
 
 int __must_check __wmi_driver_register(struct wmi_driver *driver,