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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *  ACPI-WMI mapping driver
  *
  *  Copyright (C) 2007-2008 Carlos Corbacho <carlos@strangeworlds.co.uk>
  *
  *  GUID parsing code from ldm.c is:
  *   Copyright (C) 2001,2002 Richard Russon <ldm@flatcap.org>
  *   Copyright (c) 2001-2007 Anton Altaparmakov
  *   Copyright (C) 2001,2002 Jakob Kemi <jakob.kemi@telia.com>
  *
  *  WMI bus infrastructure by Andrew Lutomirski and Darren Hart:
  *    Copyright (C) 2015 Andrew Lutomirski
  *    Copyright (C) 2017 VMware, Inc. All Rights Reserved.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/acpi.h>
 #include <linux/bits.h>
 #include <linux/build_bug.h>
 #include <linux/device.h>
 #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/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");
 MODULE_LICENSE("GPL");
 
 static LIST_HEAD(wmi_block_list);
 
 struct guid_block {
     guid_t guid;
     union {
         char object_id[2];
         struct {
             unsigned char notify_id;
             unsigned char reserved;
         };
     };
     u8 instance_count;
     u8 flags;
 } __packed;
 static_assert(sizeof(typeof_member(struct guid_block, guid)) == 16);
 static_assert(sizeof(struct guid_block) == 20);
 static_assert(__alignof__(struct guid_block) == 1);
 
 enum {  /* wmi_block flags */
     WMI_READ_TAKES_NO_ARGS,
     WMI_PROBED,
 };
 
 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;
     wmi_notify_handler handler;
     void *handler_data;
     u64 req_buf_size;
     unsigned long flags;
 };
 
 
 /*
  * If the GUID data block is marked as expensive, we must enable and
  * explicitily disable data collection.
  */
 #define ACPI_WMI_EXPENSIVE   BIT(0)
 #define ACPI_WMI_METHOD      BIT(1) /* GUID is a method */
 #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 int acpi_wmi_remove(struct platform_device *device);
 static int acpi_wmi_probe(struct platform_device *device);
 
 static const struct acpi_device_id wmi_device_ids[] = {
     {"PNP0C14", 0},
     {"pnp0c14", 0},
     { }
 };
 MODULE_DEVICE_TABLE(acpi, wmi_device_ids);
 
 static struct platform_driver acpi_wmi_driver = {
     .driver = {
         .name = "acpi-wmi",
         .acpi_match_table = wmi_device_ids,
     },
     .probe = acpi_wmi_probe,
     .remove = acpi_wmi_remove,
 };
 
 /*
  * GUID parsing functions
  */
 
 static acpi_status find_guid(const char *guid_string, struct wmi_block **out)
 {
     guid_t guid_input;
     struct wmi_block *wblock;
 
     if (!guid_string)
         return AE_BAD_PARAMETER;
 
     if (guid_parse(guid_string, &guid_input))
         return AE_BAD_PARAMETER;
 
     list_for_each_entry(wblock, &wmi_block_list, list) {
         if (guid_equal(&wblock->gblock.guid, &guid_input)) {
             if (out)
                 *out = wblock;
 
             return AE_OK;
         }
     }
 
     return AE_NOT_FOUND;
 }
 
 static const void *find_guid_context(struct wmi_block *wblock,
                      struct wmi_driver *wdriver)
 {
     const struct wmi_device_id *id;
 
     id = wdriver->id_table;
     if (!id)
         return NULL;
 
     while (*id->guid_string) {
         guid_t guid_input;
 
         if (guid_parse(id->guid_string, &guid_input))
             continue;
         if (guid_equal(&wblock->gblock.guid, &guid_input))
             return id->context;
         id++;
     }
     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;
     char method[5];
     acpi_status status;
     acpi_handle handle;
 
     block = &wblock->gblock;
     handle = wblock->acpi_device->handle;
 
     snprintf(method, 5, "WE%02X", block->notify_id);
     status = acpi_execute_simple_method(handle, method, enable);
     if (status == AE_NOT_FOUND)
         return AE_OK;
 
     return status;
 }
 
 #define WMI_ACPI_METHOD_NAME_SIZE 5
 
 static inline void get_acpi_method_name(const struct wmi_block *wblock,
                     const char method,
                     char buffer[static WMI_ACPI_METHOD_NAME_SIZE])
 {
     static_assert(ARRAY_SIZE(wblock->gblock.object_id) == 2);
     static_assert(WMI_ACPI_METHOD_NAME_SIZE >= 5);
 
     buffer[0] = 'W';
     buffer[1] = method;
     buffer[2] = wblock->gblock.object_id[0];
     buffer[3] = wblock->gblock.object_id[1];
     buffer[4] = '\0';
 }
 
 static inline acpi_object_type get_param_acpi_type(const struct wmi_block *wblock)
 {
     if (wblock->gblock.flags & ACPI_WMI_STRING)
         return ACPI_TYPE_STRING;
     else
         return ACPI_TYPE_BUFFER;
 }
 
 static acpi_status get_event_data(const struct wmi_block *wblock, struct acpi_buffer *out)
 {
     union acpi_object param = {
         .integer = {
             .type = ACPI_TYPE_INTEGER,
             .value = wblock->gblock.notify_id,
         }
     };
     struct acpi_object_list input = {
         .count = 1,
         .pointer = &param,
     };
 
     return acpi_evaluate_object(wblock->acpi_device->handle, "_WED", &input, out);
 }
 
 /*
  * Exported WMI functions
  */
 
 /**
  * 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
  */
 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_evaluate_method - Evaluate a WMI method
  * @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
  * @out: Empty buffer to return the method results
  *
  * Call an ACPI-WMI method
  */
 acpi_status wmi_evaluate_method(const char *guid_string, u8 instance, u32 method_id,
                 const struct acpi_buffer *in, struct acpi_buffer *out)
 {
     struct wmi_block *wblock = NULL;
     acpi_status status;
 
     status = find_guid(guid_string, &wblock);
     if (ACPI_FAILURE(status))
         return status;
 
     return wmidev_evaluate_method(&wblock->dev, instance, method_id,
                       in, out);
 }
 EXPORT_SYMBOL_GPL(wmi_evaluate_method);
 
 /**
  * wmidev_evaluate_method - Evaluate a WMI 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
  * @out: Empty buffer to return the method results
  *
  * Call an ACPI-WMI method
  */
 acpi_status wmidev_evaluate_method(struct wmi_device *wdev, u8 instance, u32 method_id,
                    const struct acpi_buffer *in, struct acpi_buffer *out)
 {
     struct guid_block *block;
     struct wmi_block *wblock;
     acpi_handle handle;
     struct acpi_object_list input;
     union acpi_object params[3];
     char method[WMI_ACPI_METHOD_NAME_SIZE];
 
     wblock = container_of(wdev, struct wmi_block, dev);
     block = &wblock->gblock;
     handle = wblock->acpi_device->handle;
 
     if (!(block->flags & ACPI_WMI_METHOD))
         return AE_BAD_DATA;
 
     if (block->instance_count <= instance)
         return AE_BAD_PARAMETER;
 
     input.count = 2;
     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;
     }
 
     get_acpi_method_name(wblock, 'M', method);
 
     return acpi_evaluate_object(handle, method, &input, out);
 }
 EXPORT_SYMBOL_GPL(wmidev_evaluate_method);
 
 static acpi_status __query_block(struct wmi_block *wblock, u8 instance,
                  struct acpi_buffer *out)
 {
     struct guid_block *block;
     acpi_handle handle;
     acpi_status status, wc_status = AE_ERROR;
     struct acpi_object_list input;
     union acpi_object wq_params[1];
     char wc_method[WMI_ACPI_METHOD_NAME_SIZE];
     char method[WMI_ACPI_METHOD_NAME_SIZE];
 
     if (!out)
         return AE_BAD_PARAMETER;
 
     block = &wblock->gblock;
     handle = wblock->acpi_device->handle;
 
     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 = 1;
     input.pointer = wq_params;
     wq_params[0].type = ACPI_TYPE_INTEGER;
     wq_params[0].integer.value = instance;
 
     if (instance == 0 && test_bit(WMI_READ_TAKES_NO_ARGS, &wblock->flags))
         input.count = 0;
 
     /*
      * If ACPI_WMI_EXPENSIVE, call the relevant WCxx method first to
      * enable collection.
      */
     if (block->flags & ACPI_WMI_EXPENSIVE) {
         get_acpi_method_name(wblock, 'C', wc_method);
 
         /*
          * Some GUIDs break the specification by declaring themselves
          * expensive, but have no corresponding WCxx method. So we
          * should not fail if this happens.
          */
         wc_status = acpi_execute_simple_method(handle, wc_method, 1);
     }
 
     get_acpi_method_name(wblock, 'Q', method);
     status = acpi_evaluate_object(handle, method, &input, out);
 
     /*
      * If ACPI_WMI_EXPENSIVE, call the relevant WCxx method, even if
      * the WQxx method failed - we should disable collection anyway.
      */
     if ((block->flags & ACPI_WMI_EXPENSIVE) && ACPI_SUCCESS(wc_status)) {
         /*
          * Ignore whether this WCxx call succeeds or not since
          * the previously executed WQxx method call might have
          * succeeded, and returning the failing status code
          * of this call would throw away the result of the WQxx
          * call, potentially leaking memory.
          */
         acpi_execute_simple_method(handle, wc_method, 0);
     }
 
     return status;
 }
 
 /**
  * wmi_query_block - Return contents of a WMI block (deprecated)
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
  * @instance: Instance index
  * @out: Empty buffer to return the contents of the data block to
  *
  * Return the contents of an ACPI-WMI data block to a buffer
  */
 acpi_status wmi_query_block(const char *guid_string, u8 instance,
                 struct acpi_buffer *out)
 {
     struct wmi_block *wblock;
     acpi_status status;
 
     status = find_guid(guid_string, &wblock);
     if (ACPI_FAILURE(status))
         return status;
 
     return __query_block(wblock, instance, out);
 }
 EXPORT_SYMBOL_GPL(wmi_query_block);
 
 union acpi_object *wmidev_block_query(struct wmi_device *wdev, u8 instance)
 {
     struct acpi_buffer out = { ACPI_ALLOCATE_BUFFER, NULL };
     struct wmi_block *wblock = container_of(wdev, struct wmi_block, dev);
 
     if (ACPI_FAILURE(__query_block(wblock, instance, &out)))
         return NULL;
 
     return out.pointer;
 }
 EXPORT_SYMBOL_GPL(wmidev_block_query);
 
 /**
  * wmi_set_block - Write to a WMI block
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
  * @instance: Instance index
  * @in: Buffer containing new values for the data block
  *
  * Write the contents of the input buffer to an ACPI-WMI data block
  */
 acpi_status wmi_set_block(const char *guid_string, u8 instance,
               const struct acpi_buffer *in)
 {
     struct wmi_block *wblock = NULL;
     struct guid_block *block;
     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;
 
     status = find_guid(guid_string, &wblock);
     if (ACPI_FAILURE(status))
         return status;
 
     block = &wblock->gblock;
     handle = wblock->acpi_device->handle;
 
     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;
     params[0].type = ACPI_TYPE_INTEGER;
     params[0].integer.value = instance;
     params[1].type = get_param_acpi_type(wblock);
     params[1].buffer.length = in->length;
     params[1].buffer.pointer = in->pointer;
 
     get_acpi_method_name(wblock, 'S', method);
 
     return acpi_evaluate_object(handle, method, &input, NULL);
 }
 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);
 }
 
 /**
  * wmi_install_notify_handler - Register handler for WMI events
  * @guid: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
  * @handler: Function to handle notifications
  * @data: Data to be returned to handler when event is fired
  *
  * Register a handler for events sent to the ACPI-WMI mapper device.
  */
 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;
 
     if (guid_parse(guid, &guid_input))
         return AE_BAD_PARAMETER;
 
     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_ALREADY_ACQUIRED;
 
             block->handler = handler;
             block->handler_data = data;
 
             wmi_status = wmi_method_enable(block, true);
             if ((wmi_status != AE_OK) ||
                 ((wmi_status == AE_OK) && (status == AE_NOT_EXIST)))
                 status = wmi_status;
         }
     }
 
     return status;
 }
 EXPORT_SYMBOL_GPL(wmi_install_notify_handler);
 
 /**
  * wmi_remove_notify_handler - Unregister handler for WMI events
  * @guid: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
  *
  * Unregister handler for events sent to the ACPI-WMI mapper device.
  */
 acpi_status wmi_remove_notify_handler(const char *guid)
 {
     struct wmi_block *block;
     acpi_status status = AE_NOT_EXIST;
     guid_t guid_input;
 
     if (!guid)
         return AE_BAD_PARAMETER;
 
     if (guid_parse(guid, &guid_input))
         return AE_BAD_PARAMETER;
 
     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;
             }
         }
     }
 
     return status;
 }
 EXPORT_SYMBOL_GPL(wmi_remove_notify_handler);
 
 /**
  * wmi_get_event_data - Get WMI data associated with an event
  *
  * @event: Event to find
  * @out: Buffer to hold event data. out->pointer should be freed with kfree()
  *
  * Returns extra data associated with an event in WMI.
  */
 acpi_status wmi_get_event_data(u32 event, struct acpi_buffer *out)
 {
     struct wmi_block *wblock;
 
     list_for_each_entry(wblock, &wmi_block_list, list) {
         struct guid_block *gblock = &wblock->gblock;
 
         if ((gblock->flags & ACPI_WMI_EVENT) && gblock->notify_id == event)
             return get_event_data(wblock, out);
     }
 
     return AE_NOT_FOUND;
 }
 EXPORT_SYMBOL_GPL(wmi_get_event_data);
 
 /**
  * wmi_has_guid - Check if a GUID is available
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
  *
  * Check if a given GUID is defined by _WDG
  */
 bool wmi_has_guid(const char *guid_string)
 {
     return ACPI_SUCCESS(find_guid(guid_string, NULL));
 }
 EXPORT_SYMBOL_GPL(wmi_has_guid);
 
 /**
  * wmi_get_acpi_device_uid() - Get _UID name of ACPI device that defines GUID
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
  *
  * Find the _UID of ACPI device associated with this WMI GUID.
  *
  * Return: The ACPI _UID field value or NULL if the WMI GUID was not found
  */
 char *wmi_get_acpi_device_uid(const char *guid_string)
 {
     struct wmi_block *wblock = NULL;
     acpi_status status;
 
     status = find_guid(guid_string, &wblock);
     if (ACPI_FAILURE(status))
         return NULL;
 
     return acpi_device_uid(wblock->acpi_device);
 }
 EXPORT_SYMBOL_GPL(wmi_get_acpi_device_uid);
 
 static struct wmi_block *dev_to_wblock(struct device *dev)
 {
     return container_of(dev, struct wmi_block, dev.dev);
 }
 
 static struct wmi_device *dev_to_wdev(struct device *dev)
 {
     return container_of(dev, struct wmi_device, dev);
 }
 
 static inline struct wmi_driver *drv_to_wdrv(struct device_driver *drv)
 {
     return container_of(drv, struct wmi_driver, driver);
 }
 
 /*
  * sysfs interface
  */
 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
                  char *buf)
 {
     struct wmi_block *wblock = dev_to_wblock(dev);
 
     return sysfs_emit(buf, "wmi:%pUL\n", &wblock->gblock.guid);
 }
 static DEVICE_ATTR_RO(modalias);
 
 static ssize_t guid_show(struct device *dev, struct device_attribute *attr,
              char *buf)
 {
     struct wmi_block *wblock = dev_to_wblock(dev);
 
     return sysfs_emit(buf, "%pUL\n", &wblock->gblock.guid);
 }
 static DEVICE_ATTR_RO(guid);
 
 static ssize_t instance_count_show(struct device *dev,
                    struct device_attribute *attr, char *buf)
 {
     struct wmi_block *wblock = dev_to_wblock(dev);
 
     return sysfs_emit(buf, "%d\n", (int)wblock->gblock.instance_count);
 }
 static DEVICE_ATTR_RO(instance_count);
 
 static ssize_t expensive_show(struct device *dev,
                   struct device_attribute *attr, char *buf)
 {
     struct wmi_block *wblock = dev_to_wblock(dev);
 
     return sysfs_emit(buf, "%d\n",
               (wblock->gblock.flags & ACPI_WMI_EXPENSIVE) != 0);
 }
 static DEVICE_ATTR_RO(expensive);
 
 static struct attribute *wmi_attrs[] = {
     &dev_attr_modalias.attr,
     &dev_attr_guid.attr,
     &dev_attr_instance_count.attr,
     &dev_attr_expensive.attr,
     NULL
 };
 ATTRIBUTE_GROUPS(wmi);
 
 static ssize_t notify_id_show(struct device *dev, struct device_attribute *attr,
                   char *buf)
 {
     struct wmi_block *wblock = dev_to_wblock(dev);
 
     return sysfs_emit(buf, "%02X\n", (unsigned int)wblock->gblock.notify_id);
 }
 static DEVICE_ATTR_RO(notify_id);
 
 static struct attribute *wmi_event_attrs[] = {
     &dev_attr_notify_id.attr,
     NULL
 };
 ATTRIBUTE_GROUPS(wmi_event);
 
 static ssize_t object_id_show(struct device *dev, struct device_attribute *attr,
                   char *buf)
 {
     struct wmi_block *wblock = dev_to_wblock(dev);
 
     return sysfs_emit(buf, "%c%c\n", wblock->gblock.object_id[0],
               wblock->gblock.object_id[1]);
 }
 static DEVICE_ATTR_RO(object_id);
 
 static ssize_t setable_show(struct device *dev, struct device_attribute *attr,
                 char *buf)
 {
     struct wmi_device *wdev = dev_to_wdev(dev);
 
     return sysfs_emit(buf, "%d\n", (int)wdev->setable);
 }
 static DEVICE_ATTR_RO(setable);
 
 static struct attribute *wmi_data_attrs[] = {
     &dev_attr_object_id.attr,
     &dev_attr_setable.attr,
     NULL
 };
 ATTRIBUTE_GROUPS(wmi_data);
 
 static struct attribute *wmi_method_attrs[] = {
     &dev_attr_object_id.attr,
     NULL
 };
 ATTRIBUTE_GROUPS(wmi_method);
 
 static int wmi_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
     struct wmi_block *wblock = dev_to_wblock(dev);
 
     if (add_uevent_var(env, "MODALIAS=wmi:%pUL", &wblock->gblock.guid))
         return -ENOMEM;
 
     if (add_uevent_var(env, "WMI_GUID=%pUL", &wblock->gblock.guid))
         return -ENOMEM;
 
     return 0;
 }
 
 static void wmi_dev_release(struct device *dev)
 {
     struct wmi_block *wblock = dev_to_wblock(dev);
 
     kfree(wblock);
 }
 
 static int wmi_dev_match(struct device *dev, struct device_driver *driver)
 {
     struct wmi_driver *wmi_driver = drv_to_wdrv(driver);
     struct wmi_block *wblock = dev_to_wblock(dev);
     const struct wmi_device_id *id = wmi_driver->id_table;
 
     if (id == NULL)
         return 0;
 
     while (*id->guid_string) {
         guid_t driver_guid;
 
         if (WARN_ON(guid_parse(id->guid_string, &driver_guid)))
             continue;
         if (guid_equal(&driver_guid, &wblock->gblock.guid))
             return 1;
 
         id++;
     }
 
     return 0;
 }
 static int wmi_char_open(struct inode *inode, struct file *filp)
 {
     const char *driver_name = filp->f_path.dentry->d_iname;
     struct wmi_block *wblock;
     struct wmi_block *next;
 
     list_for_each_entry_safe(wblock, next, &wmi_block_list, list) {
         if (!wblock->dev.dev.driver)
             continue;
         if (strcmp(driver_name, wblock->dev.dev.driver->name) == 0) {
             filp->private_data = wblock;
             break;
         }
     }
 
     if (!filp->private_data)
         return -ENODEV;
 
     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)
 {
     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;
 
     /* make sure we're not calling a higher instance than exists*/
     if (_IOC_NR(cmd) >= wblock->gblock.instance_count)
         return -EINVAL;
 
     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;
     }
 
     /* 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;
     }
 
 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;
         }
     }
 
     set_bit(WMI_PROBED, &wblock->flags);
     return 0;
 
 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;
 }
 
 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);
     }
 
     if (wdriver->remove)
         wdriver->remove(dev_to_wdev(dev));
 
     if (ACPI_FAILURE(wmi_method_enable(wblock, false)))
         dev_warn(dev, "failed to disable device\n");
 }
 
 static struct class wmi_bus_class = {
     .name = "wmi_bus",
 };
 
 static struct bus_type wmi_bus_type = {
     .name = "wmi",
     .dev_groups = wmi_groups,
     .match = wmi_dev_match,
     .uevent = wmi_dev_uevent,
     .probe = wmi_dev_probe,
     .remove = wmi_dev_remove,
 };
 
 static const struct device_type wmi_type_event = {
     .name = "event",
     .groups = wmi_event_groups,
     .release = wmi_dev_release,
 };
 
 static const struct device_type wmi_type_method = {
     .name = "method",
     .groups = wmi_method_groups,
     .release = wmi_dev_release,
 };
 
 static const struct device_type wmi_type_data = {
     .name = "data",
     .groups = wmi_data_groups,
     .release = wmi_dev_release,
 };
 
 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;
 
     if (wblock->gblock.flags & ACPI_WMI_EVENT) {
         wblock->dev.dev.type = &wmi_type_event;
         goto out_init;
     }
 
     if (wblock->gblock.flags & ACPI_WMI_METHOD) {
         wblock->dev.dev.type = &wmi_type_method;
         mutex_init(&wblock->char_mutex);
         goto out_init;
     }
 
     /*
      * Data Block Query Control Method (WQxx by convention) is
      * required per the WMI documentation. If it is not present,
      * we ignore this data block.
      */
     get_acpi_method_name(wblock, 'Q', method);
     result = get_subobj_info(device->handle, method, &info);
 
     if (result) {
         dev_warn(wmi_bus_dev,
              "%s data block query control method not found\n",
              method);
         return result;
     }
 
     wblock->dev.dev.type = &wmi_type_data;
 
     /*
      * The Microsoft documentation specifically states:
      *
      *   Data blocks registered with only a single instance
      *   can ignore the parameter.
      *
      * ACPICA will get mad at us if we call the method with the wrong number
      * of arguments, so check what our method expects.  (On some Dell
      * laptops, WQxx may not be a method at all.)
      */
     if (info->type != ACPI_TYPE_METHOD || info->param_count == 0)
         set_bit(WMI_READ_TAKES_NO_ARGS, &wblock->flags);
 
     kfree(info);
 
     get_acpi_method_name(wblock, 'S', method);
     result = get_subobj_info(device->handle, method, NULL);
 
     if (result == 0)
         wblock->dev.setable = true;
 
  out_init:
     wblock->dev.dev.bus = &wmi_bus_type;
     wblock->dev.dev.parent = wmi_bus_dev;
 
     dev_set_name(&wblock->dev.dev, "%pUL", &wblock->gblock.guid);
 
     device_initialize(&wblock->dev.dev);
 
     return 0;
 }
 
 static void wmi_free_devices(struct acpi_device *device)
 {
     struct wmi_block *wblock, *next;
 
     /* Delete devices for all the GUIDs */
     list_for_each_entry_safe(wblock, next, &wmi_block_list, list) {
         if (wblock->acpi_device == device) {
             list_del(&wblock->list);
             device_unregister(&wblock->dev.dev);
         }
     }
 }
 
 static bool guid_already_parsed(struct acpi_device *device, const guid_t *guid)
 {
     struct wmi_block *wblock;
 
     list_for_each_entry(wblock, &wmi_block_list, list) {
         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
  */
 static int parse_wdg(struct device *wmi_bus_dev, struct acpi_device *device)
 {
     struct acpi_buffer out = {ACPI_ALLOCATE_BUFFER, NULL};
     const struct guid_block *gblock;
     struct wmi_block *wblock, *next;
     union acpi_object *obj;
     acpi_status status;
     int retval = 0;
     u32 i, total;
 
     status = acpi_evaluate_object(device->handle, "_WDG", NULL, &out);
     if (ACPI_FAILURE(status))
         return -ENXIO;
 
     obj = out.pointer;
     if (!obj)
         return -ENXIO;
 
     if (obj->type != ACPI_TYPE_BUFFER) {
         retval = -ENXIO;
         goto out_free_pointer;
     }
 
     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]);
 
         /*
          * Some WMI devices, like those for nVidia hooks, have a
          * duplicate GUID. It's not clear what we should do in this
          * case yet, so for now, we'll just ignore the duplicate
          * for device creation.
          */
         if (guid_already_parsed(device, &gblock[i].guid))
             continue;
 
         wblock = kzalloc(sizeof(*wblock), GFP_KERNEL);
         if (!wblock) {
             retval = -ENOMEM;
             break;
         }
 
         wblock->acpi_device = device;
         wblock->gblock = gblock[i];
 
         retval = wmi_create_device(wmi_bus_dev, wblock, device);
         if (retval) {
             kfree(wblock);
             continue;
         }
 
         list_add_tail(&wblock->list, &wmi_block_list);
 
         if (debug_event) {
             wblock->handler = wmi_notify_debug;
             wmi_method_enable(wblock, true);
         }
     }
 
     /*
      * Now that all of the devices are created, add them to the
      * device tree and probe subdrivers.
      */
     list_for_each_entry_safe(wblock, next, &wmi_block_list, list) {
         if (wblock->acpi_device != device)
             continue;
 
         retval = device_add(&wblock->dev.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);
         }
     }
 
 out_free_pointer:
     kfree(out.pointer);
     return retval;
 }
 
 /*
  * WMI can have EmbeddedControl access regions. In which case, we just want to
  * hand these off to the EC driver.
  */
 static acpi_status
 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;
     u8 temp = 0;
 
     if ((address > 0xFF) || !value)
         return AE_BAD_PARAMETER;
 
     if (function != ACPI_READ && function != ACPI_WRITE)
         return AE_BAD_PARAMETER;
 
     if (bits != 8)
         return AE_BAD_PARAMETER;
 
     if (function == ACPI_READ) {
         result = ec_read(address, &temp);
         (*value) |= ((u64)temp) << i;
     } else {
         temp = 0xff & ((*value) >> i);
         result = ec_write(address, temp);
     }
 
     switch (result) {
     case -EINVAL:
         return AE_BAD_PARAMETER;
     case -ENODEV:
         return AE_NOT_FOUND;
     case -ETIME:
         return AE_TIME;
     default:
         return AE_OK;
     }
 }
 
 static void acpi_wmi_notify_handler(acpi_handle handle, u32 event,
                     void *context)
 {
     struct wmi_block *wblock = NULL, *iter;
 
     list_for_each_entry(iter, &wmi_block_list, list) {
         struct guid_block *block = &iter->gblock;
 
         if (iter->acpi_device->handle == handle &&
             (block->flags & ACPI_WMI_EVENT) &&
             (block->notify_id == event)) {
             wblock = iter;
             break;
         }
     }
 
     if (!wblock)
         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, evdata.pointer);
 
         kfree(evdata.pointer);
     } else if (wblock->handler) {
         /* Legacy handler */
         wblock->handler(event, wblock->handler_data);
     }
 
     if (debug_event)
         pr_info("DEBUG: GUID %pUL event 0x%02X\n", &wblock->gblock.guid, event);
 
     acpi_bus_generate_netlink_event(
         wblock->acpi_device->pnp.device_class,
         dev_name(&wblock->dev.dev),
         event, 0);
 }
 
 static int acpi_wmi_remove(struct platform_device *device)
 {
     struct acpi_device *acpi_device = ACPI_COMPANION(&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);
     wmi_free_devices(acpi_device);
     device_unregister(dev_get_drvdata(&device->dev));
 
     return 0;
 }
 
 static int acpi_wmi_probe(struct platform_device *device)
 {
     struct acpi_device *acpi_device;
     struct device *wmi_bus_dev;
     acpi_status status;
     int error;
 
     acpi_device = ACPI_COMPANION(&device->dev);
     if (!acpi_device) {
         dev_err(&device->dev, "ACPI companion is missing\n");
         return -ENODEV;
     }
 
     status = acpi_install_address_space_handler(acpi_device->handle,
                             ACPI_ADR_SPACE_EC,
                             &acpi_wmi_ec_space_handler,
                             NULL, NULL);
     if (ACPI_FAILURE(status)) {
         dev_err(&device->dev, "Error installing EC region handler\n");
         return -ENODEV;
     }
 
     status = acpi_install_notify_handler(acpi_device->handle,
                          ACPI_ALL_NOTIFY,
                          acpi_wmi_notify_handler,
                          NULL);
     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;
     }
     dev_set_drvdata(&device->dev, wmi_bus_dev);
 
     error = parse_wdg(wmi_bus_dev, acpi_device);
     if (error) {
         pr_err("Failed to parse WDG method\n");
         goto err_remove_busdev;
     }
 
     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,
                        struct module *owner)
 {
     driver->driver.owner = owner;
     driver->driver.bus = &wmi_bus_type;
 
     return driver_register(&driver->driver);
 }
 EXPORT_SYMBOL(__wmi_driver_register);
 
 void wmi_driver_unregister(struct wmi_driver *driver)
 {
     driver_unregister(&driver->driver);
 }
 EXPORT_SYMBOL(wmi_driver_unregister);
 
 static int __init acpi_wmi_init(void)
 {
     int error;
 
     if (acpi_disabled)
         return -ENODEV;
 
     error = class_register(&wmi_bus_class);
     if (error)
         return error;
 
     error = bus_register(&wmi_bus_type);
     if (error)
         goto err_unreg_class;
 
     error = platform_driver_register(&acpi_wmi_driver);
     if (error) {
         pr_err("Error loading mapper\n");
         goto err_unreg_bus;
     }
 
     return 0;
 
 err_unreg_bus:
     bus_unregister(&wmi_bus_type);
 
 err_unreg_class:
     class_unregister(&wmi_bus_class);
 
     return error;
 }
 
 static void __exit acpi_wmi_exit(void)
 {
     platform_driver_unregister(&acpi_wmi_driver);
     bus_unregister(&wmi_bus_type);
     class_unregister(&wmi_bus_class);
 }
 
 subsys_initcall_sync(acpi_wmi_init);
 module_exit(acpi_wmi_exit);

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