path: root/drivers/platform/wmi/core.c

// 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/idr.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/limits.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/uuid.h>
#include <linux/wmi.h>
#include <linux/fs.h>

#include "internal.h"

MODULE_AUTHOR("Carlos Corbacho");
MODULE_DESCRIPTION("ACPI-WMI Mapping Driver");
MODULE_LICENSE("GPL");

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_GUID_DUPLICATED,
	WMI_NO_EVENT_DATA,
};

struct wmi_block {
	struct wmi_device dev;
	struct guid_block gblock;
	struct acpi_device *acpi_device;
	struct rw_semaphore notify_lock;	/* Protects notify callback add/remove */
	wmi_notify_handler handler;
	void *handler_data;
	bool driver_ready;
	unsigned long flags;
};

struct wmi_guid_count_context {
	const guid_t *guid;
	int count;
};

static DEFINE_IDA(wmi_ida);

/*
 * 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 const struct acpi_device_id wmi_device_ids[] = {
	{"PNP0C14", 0},
	{"pnp0c14", 0},
	{ }
};
MODULE_DEVICE_TABLE(acpi, wmi_device_ids);

#define dev_to_wblock(__dev)	container_of_const(__dev, struct wmi_block, dev.dev)

/*
 * GUID parsing functions
 */

static bool guid_parse_and_compare(const char *string, const guid_t *guid)
{
	guid_t guid_input;

	if (guid_parse(string, &guid_input))
		return false;

	return guid_equal(&guid_input, guid);
}

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) {
		if (guid_parse_and_compare(id->guid_string, &wblock->gblock.guid))
			return id->context;
		id++;
	}
	return NULL;
}

#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 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 const struct bus_type wmi_bus_type;

static const struct device_type wmi_type_event;

static const struct device_type wmi_type_method;

static int wmi_device_enable(struct wmi_device *wdev, bool enable)
{
	struct wmi_block *wblock = container_of(wdev, struct wmi_block, dev);
	char method[WMI_ACPI_METHOD_NAME_SIZE];
	acpi_handle handle;
	acpi_status status;

	if (wblock->dev.dev.type == &wmi_type_method)
		return 0;

	if (wblock->dev.dev.type == &wmi_type_event) {
		/*
		 * Windows always enables/disables WMI events, even when they are
		 * not marked as being expensive. We follow this behavior for
		 * compatibility reasons.
		 */
		snprintf