hid-core.c 62.8 KB
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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 *  HID support for Linux
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 *
 *  Copyright (c) 1999 Andreas Gal
 *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
 *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
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 *  Copyright (c) 2006-2012 Jiri Kosina
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 */

/*
 */

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <asm/unaligned.h>
#include <asm/byteorder.h>
#include <linux/input.h>
#include <linux/wait.h>
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#include <linux/vmalloc.h>
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#include <linux/sched.h>
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#include <linux/semaphore.h>
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#include <linux/hid.h>
#include <linux/hiddev.h>
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#include <linux/hid-debug.h>
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#include <linux/hidraw.h>
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#include "hid-ids.h"

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/*
 * Version Information
 */

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#define DRIVER_DESC "HID core driver"
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int hid_debug = 0;
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module_param_named(debug, hid_debug, int, 0600);
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MODULE_PARM_DESC(debug, "toggle HID debugging messages");
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EXPORT_SYMBOL_GPL(hid_debug);

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static int hid_ignore_special_drivers = 0;
module_param_named(ignore_special_drivers, hid_ignore_special_drivers, int, 0600);
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MODULE_PARM_DESC(ignore_special_drivers, "Ignore any special drivers and handle all devices by generic driver");
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/*
 * Register a new report for a device.
 */

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struct hid_report *hid_register_report(struct hid_device *device,
				       unsigned int type, unsigned int id,
				       unsigned int application)
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{
	struct hid_report_enum *report_enum = device->report_enum + type;
	struct hid_report *report;

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	if (id >= HID_MAX_IDS)
		return NULL;
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	if (report_enum->report_id_hash[id])
		return report_enum->report_id_hash[id];

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	report = kzalloc(sizeof(struct hid_report), GFP_KERNEL);
	if (!report)
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		return NULL;

	if (id != 0)
		report_enum->numbered = 1;

	report->id = id;
	report->type = type;
	report->size = 0;
	report->device = device;
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	report->application = application;
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	report_enum->report_id_hash[id] = report;

	list_add_tail(&report->list, &report_enum->report_list);

	return report;
}
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EXPORT_SYMBOL_GPL(hid_register_report);
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/*
 * Register a new field for this report.
 */

static struct hid_field *hid_register_field(struct hid_report *report, unsigned usages, unsigned values)
{
	struct hid_field *field;

	if (report->maxfield == HID_MAX_FIELDS) {
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		hid_err(report->device, "too many fields in report\n");
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		return NULL;
	}

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	field = kzalloc((sizeof(struct hid_field) +
			 usages * sizeof(struct hid_usage) +
			 values * sizeof(unsigned)), GFP_KERNEL);
	if (!field)
		return NULL;
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	field->index = report->maxfield++;
	report->field[field->index] = field;
	field->usage = (struct hid_usage *)(field + 1);
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	field->value = (s32 *)(field->usage + usages);
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	field->report = report;

	return field;
}

/*
 * Open a collection. The type/usage is pushed on the stack.
 */

static int open_collection(struct hid_parser *parser, unsigned type)
{
	struct hid_collection *collection;
	unsigned usage;
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	int collection_index;
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	usage = parser->local.usage[0];

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	if (parser->collection_stack_ptr == parser->collection_stack_size) {
		unsigned int *collection_stack;
		unsigned int new_size = parser->collection_stack_size +
					HID_COLLECTION_STACK_SIZE;

		collection_stack = krealloc(parser->collection_stack,
					    new_size * sizeof(unsigned int),
					    GFP_KERNEL);
		if (!collection_stack)
			return -ENOMEM;

		parser->collection_stack = collection_stack;
		parser->collection_stack_size = new_size;
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	}

	if (parser->device->maxcollection == parser->device->collection_size) {
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		collection = kmalloc(
				array3_size(sizeof(struct hid_collection),
					    parser->device->collection_size,
					    2),
				GFP_KERNEL);
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		if (collection == NULL) {
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			hid_err(parser->device, "failed to reallocate collection array\n");
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			return -ENOMEM;
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		}
		memcpy(collection, parser->device->collection,
			sizeof(struct hid_collection) *
			parser->device->collection_size);
		memset(collection + parser->device->collection_size, 0,
			sizeof(struct hid_collection) *
			parser->device->collection_size);
		kfree(parser->device->collection);
		parser->device->collection = collection;
		parser->device->collection_size *= 2;
	}

	parser->collection_stack[parser->collection_stack_ptr++] =
		parser->device->maxcollection;

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	collection_index = parser->device->maxcollection++;
	collection = parser->device->collection + collection_index;
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	collection->type = type;
	collection->usage = usage;
	collection->level = parser->collection_stack_ptr - 1;
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	collection->parent_idx = (collection->level == 0) ? -1 :
		parser->collection_stack[collection->level - 1];
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	if (type == HID_COLLECTION_APPLICATION)
		parser->device->maxapplication++;

	return 0;
}

/*
 * Close a collection.
 */

static int close_collection(struct hid_parser *parser)
{
	if (!parser->collection_stack_ptr) {
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		hid_err(parser->device, "collection stack underflow\n");
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		return -EINVAL;
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	}
	parser->collection_stack_ptr--;
	return 0;
}

/*
 * Climb up the stack, search for the specified collection type
 * and return the usage.
 */

static unsigned hid_lookup_collection(struct hid_parser *parser, unsigned type)
{
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	struct hid_collection *collection = parser->device->collection;
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	int n;
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	for (n = parser->collection_stack_ptr - 1; n >= 0; n--) {
		unsigned index = parser->collection_stack[n];
		if (collection[index].type == type)
			return collection[index].usage;
	}
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	return 0; /* we know nothing about this usage type */
}

/*
 * Add a usage to the temporary parser table.
 */

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static int hid_add_usage(struct hid_parser *parser, unsigned usage, u8 size)
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{
	if (parser->local.usage_index >= HID_MAX_USAGES) {
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		hid_err(parser->device, "usage index exceeded\n");
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		return -1;
	}
	parser->local.usage[parser->local.usage_index] = usage;
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	parser->local.usage_size[parser->local.usage_index] = size;
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	parser->local.collection_index[parser->local.usage_index] =
		parser->collection_stack_ptr ?
		parser->collection_stack[parser->collection_stack_ptr - 1] : 0;
	parser->local.usage_index++;
	return 0;
}

/*
 * Register a new field for this report.
 */

static int hid_add_field(struct hid_parser *parser, unsigned report_type, unsigned flags)
{
	struct hid_report *report;
	struct hid_field *field;
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	unsigned int usages;
	unsigned int offset;
	unsigned int i;
	unsigned int application;
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	application = hid_lookup_collection(parser, HID_COLLECTION_APPLICATION);

	report = hid_register_report(parser->device, report_type,
				     parser->global.report_id, application);
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	if (!report) {
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		hid_err(parser->device, "hid_register_report failed\n");
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		return -1;
	}

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	/* Handle both signed and unsigned cases properly */
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	if ((parser->global.logical_minimum < 0 &&
		parser->global.logical_maximum <
		parser->global.logical_minimum) ||
		(parser->global.logical_minimum >= 0 &&
		(__u32)parser->global.logical_maximum <
		(__u32)parser->global.logical_minimum)) {
		dbg_hid("logical range invalid 0x%x 0x%x\n",
			parser->global.logical_minimum,
			parser->global.logical_maximum);
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		return -1;
	}

	offset = report->size;
	report->size += parser->global.report_size * parser->global.report_count;

	if (!parser->local.usage_index) /* Ignore padding fields */
		return 0;

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	usages = max_t(unsigned, parser->local.usage_index,
				 parser->global.report_count);
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	field = hid_register_field(report, usages, parser->global.report_count);
	if (!field)
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		return 0;

	field->physical = hid_lookup_collection(parser, HID_COLLECTION_PHYSICAL);
	field->logical = hid_lookup_collection(parser, HID_COLLECTION_LOGICAL);
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	field->application = application;
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	for (i = 0; i < usages; i++) {
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		unsigned j = i;
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		/* Duplicate the last usage we parsed if we have excess values */
		if (i >= parser->local.usage_index)
			j = parser->local.usage_index - 1;
		field->usage[i].hid = parser->local.usage[j];
		field->usage[i].collection_index =
			parser->local.collection_index[j];
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		field->usage[i].usage_index = i;
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		field->usage[i].resolution_multiplier = 1;
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	}

	field->maxusage = usages;
	field->flags = flags;
	field->report_offset = offset;
	field->report_type = report_type;
	field->report_size = parser->global.report_size;
	field->report_count = parser->global.report_count;
	field->logical_minimum = parser->global.logical_minimum;
	field->logical_maximum = parser->global.logical_maximum;
	field->physical_minimum = parser->global.physical_minimum;
	field->physical_maximum = parser->global.physical_maximum;
	field->unit_exponent = parser->global.unit_exponent;
	field->unit = parser->global.unit;

	return 0;
}

/*
 * Read data value from item.
 */

static u32 item_udata(struct hid_item *item)
{
	switch (item->size) {
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	case 1: return item->data.u8;
	case 2: return item->data.u16;
	case 4: return item->data.u32;
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	}
	return 0;
}

static s32 item_sdata(struct hid_item *item)
{
	switch (item->size) {
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	case 1: return item->data.s8;
	case 2: return item->data.s16;
	case 4: return item->data.s32;
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	}
	return 0;
}

/*
 * Process a global item.
 */

static int hid_parser_global(struct hid_parser *parser, struct hid_item *item)
{
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	__s32 raw_value;
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	switch (item->tag) {
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	case HID_GLOBAL_ITEM_TAG_PUSH:
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		if (parser->global_stack_ptr == HID_GLOBAL_STACK_SIZE) {
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			hid_err(parser->device, "global environment stack overflow\n");
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			return -1;
		}
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		memcpy(parser->global_stack + parser->global_stack_ptr++,
			&parser->global, sizeof(struct hid_global));
		return 0;
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	case HID_GLOBAL_ITEM_TAG_POP:
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		if (!parser->global_stack_ptr) {
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			hid_err(parser->device, "global environment stack underflow\n");
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			return -1;
		}
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		memcpy(&parser->global, parser->global_stack +
			--parser->global_stack_ptr, sizeof(struct hid_global));
		return 0;
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	case HID_GLOBAL_ITEM_TAG_USAGE_PAGE:
		parser->global.usage_page = item_udata(item);
		return 0;
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	case HID_GLOBAL_ITEM_TAG_LOGICAL_MINIMUM:
		parser->global.logical_minimum = item_sdata(item);
		return 0;
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	case HID_GLOBAL_ITEM_TAG_LOGICAL_MAXIMUM:
		if (parser->global.logical_minimum < 0)
			parser->global.logical_maximum = item_sdata(item);
		else
			parser->global.logical_maximum = item_udata(item);
		return 0;
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	case HID_GLOBAL_ITEM_TAG_PHYSICAL_MINIMUM:
		parser->global.physical_minimum = item_sdata(item);
		return 0;
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	case HID_GLOBAL_ITEM_TAG_PHYSICAL_MAXIMUM:
		if (parser->global.physical_minimum < 0)
			parser->global.physical_maximum = item_sdata(item);
		else
			parser->global.physical_maximum = item_udata(item);
		return 0;
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	case HID_GLOBAL_ITEM_TAG_UNIT_EXPONENT:
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		/* Many devices provide unit exponent as a two's complement
		 * nibble due to the common misunderstanding of HID
		 * specification 1.11, 6.2.2.7 Global Items. Attempt to handle
		 * both this and the standard encoding. */
		raw_value = item_sdata(item);
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		if (!(raw_value & 0xfffffff0))
			parser->global.unit_exponent = hid_snto32(raw_value, 4);
		else
			parser->global.unit_exponent = raw_value;
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		return 0;
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	case HID_GLOBAL_ITEM_TAG_UNIT:
		parser->global.unit = item_udata(item);
		return 0;
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	case HID_GLOBAL_ITEM_TAG_REPORT_SIZE:
		parser->global.report_size = item_udata(item);
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		if (parser->global.report_size > 256) {
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			hid_err(parser->device, "invalid report_size %d\n",
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					parser->global.report_size);
			return -1;
		}
		return 0;
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	case HID_GLOBAL_ITEM_TAG_REPORT_COUNT:
		parser->global.report_count = item_udata(item);
		if (parser->global.report_count > HID_MAX_USAGES) {
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			hid_err(parser->device, "invalid report_count %d\n",
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					parser->global.report_count);
			return -1;
		}
		return 0;
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	case HID_GLOBAL_ITEM_TAG_REPORT_ID:
		parser->global.report_id = item_udata(item);
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		if (parser->global.report_id == 0 ||
		    parser->global.report_id >= HID_MAX_IDS) {
			hid_err(parser->device, "report_id %u is invalid\n",
				parser->global.report_id);
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			return -1;
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		}
		return 0;

	default:
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		hid_err(parser->device, "unknown global tag 0x%x\n", item->tag);
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		return -1;
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	}
}

/*
 * Process a local item.
 */

static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
{
	__u32 data;
	unsigned n;
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	__u32 count;
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	data = item_udata(item);

	switch (item->tag) {
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	case HID_LOCAL_ITEM_TAG_DELIMITER:

		if (data) {
			/*
			 * We treat items before the first delimiter
			 * as global to all usage sets (branch 0).
			 * In the moment we process only these global
			 * items and the first delimiter set.
			 */
			if (parser->local.delimiter_depth != 0) {
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				hid_err(parser->device, "nested delimiters\n");
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				return -1;
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			}
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			parser->local.delimiter_depth++;
			parser->local.delimiter_branch++;
		} else {
			if (parser->local.delimiter_depth < 1) {
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				hid_err(parser->device, "bogus close delimiter\n");
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				return -1;
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			}
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			parser->local.delimiter_depth--;
		}
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		return 0;
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	case HID_LOCAL_ITEM_TAG_USAGE:
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		if (parser->local.delimiter_branch > 1) {
			dbg_hid("alternative usage ignored\n");
			return 0;
		}
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		return hid_add_usage(parser, data, item->size);
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	case HID_LOCAL_ITEM_TAG_USAGE_MINIMUM:
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		if (parser->local.delimiter_branch > 1) {
			dbg_hid("alternative usage ignored\n");
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			return 0;
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		}
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		parser->local.usage_minimum = data;
		return 0;
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	case HID_LOCAL_ITEM_TAG_USAGE_MAXIMUM:
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		if (parser->local.delimiter_branch > 1) {
			dbg_hid("alternative usage ignored\n");
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			return 0;
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		}
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		count = data - parser->local.usage_minimum;
		if (count + parser->local.usage_index >= HID_MAX_USAGES) {
			/*
			 * We do not warn if the name is not set, we are
			 * actually pre-scanning the device.
			 */
			if (dev_name(&parser->device->dev))
				hid_warn(parser->device,
					 "ignoring exceeding usage max\n");
			data = HID_MAX_USAGES - parser->local.usage_index +
				parser->local.usage_minimum - 1;
			if (data <= 0) {
				hid_err(parser->device,
					"no more usage index available\n");
				return -1;
			}
		}

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		for (n = parser->local.usage_minimum; n <= data; n++)
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			if (hid_add_usage(parser, n, item->size)) {
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				dbg_hid("hid_add_usage failed\n");
				return -1;
			}
		return 0;

	default:

		dbg_hid("unknown local item tag 0x%x\n", item->tag);
		return 0;
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	}
	return 0;
}

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/*
 * Concatenate Usage Pages into Usages where relevant:
 * As per specification, 6.2.2.8: "When the parser encounters a main item it
 * concatenates the last declared Usage Page with a Usage to form a complete
 * usage value."
 */

static void hid_concatenate_usage_page(struct hid_parser *parser)
{
	int i;

	for (i = 0; i < parser->local.usage_index; i++)
		if (parser->local.usage_size[i] <= 2)
			parser->local.usage[i] += parser->global.usage_page << 16;
}

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/*
 * Process a main item.
 */

static int hid_parser_main(struct hid_parser *parser, struct hid_item *item)
{
	__u32 data;
	int ret;

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	hid_concatenate_usage_page(parser);

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	data = item_udata(item);

	switch (item->tag) {
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	case HID_MAIN_ITEM_TAG_BEGIN_COLLECTION:
		ret = open_collection(parser, data & 0xff);
		break;
	case HID_MAIN_ITEM_TAG_END_COLLECTION:
		ret = close_collection(parser);
		break;
	case HID_MAIN_ITEM_TAG_INPUT:
		ret = hid_add_field(parser, HID_INPUT_REPORT, data);
		break;
	case HID_MAIN_ITEM_TAG_OUTPUT:
		ret = hid_add_field(parser, HID_OUTPUT_REPORT, data);
		break;
	case HID_MAIN_ITEM_TAG_FEATURE:
		ret = hid_add_field(parser, HID_FEATURE_REPORT, data);
		break;
	default:
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		hid_warn(parser->device, "unknown main item tag 0x%x\n", item->tag);
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		ret = 0;
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	}

	memset(&parser->local, 0, sizeof(parser->local));	/* Reset the local parser environment */

	return ret;
}

/*
 * Process a reserved item.
 */

static int hid_parser_reserved(struct hid_parser *parser, struct hid_item *item)
{
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	dbg_hid("reserved item type, tag 0x%x\n", item->tag);
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	return 0;
}

/*
 * Free a report and all registered fields. The field->usage and
 * field->value table's are allocated behind the field, so we need
 * only to free(field) itself.
 */

static void hid_free_report(struct hid_report *report)
{
	unsigned n;

	for (n = 0; n < report->maxfield; n++)
		kfree(report->field[n]);
	kfree(report);
}

/*
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 * Close report. This function returns the device
 * state to the point prior to hid_open_report().
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 */
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static void hid_close_report(struct hid_device *device)
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{
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	unsigned i, j;
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	for (i = 0; i < HID_REPORT_TYPES; i++) {
		struct hid_report_enum *report_enum = device->report_enum + i;

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		for (j = 0; j < HID_MAX_IDS; j++) {
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			struct hid_report *report = report_enum->report_id_hash[j];
			if (report)
				hid_free_report(report);
		}
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		memset(report_enum, 0, sizeof(*report_enum));
		INIT_LIST_HEAD(&report_enum->report_list);
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	}

	kfree(device->rdesc);
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	device->rdesc = NULL;
	device->rsize = 0;

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	kfree(device->collection);
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	device->collection = NULL;
	device->collection_size = 0;
	device->maxcollection = 0;
	device->maxapplication = 0;

	device->status &= ~HID_STAT_PARSED;
}

/*
 * Free a device structure, all reports, and all fields.
 */

static void hid_device_release(struct device *dev)
{
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	struct hid_device *hid = to_hid_device(dev);
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	hid_close_report(hid);
	kfree(hid->dev_rdesc);
	kfree(hid);
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}

/*
 * Fetch a report description item from the data stream. We support long
 * items, though they are not used yet.
 */

static u8 *fetch_item(__u8 *start, __u8 *end, struct hid_item *item)
{
	u8 b;

	if ((end - start) <= 0)
		return NULL;

	b = *start++;

	item->type = (b >> 2) & 3;
	item->tag  = (b >> 4) & 15;

	if (item->tag == HID_ITEM_TAG_LONG) {

		item->format = HID_ITEM_FORMAT_LONG;

		if ((end - start) < 2)
			return NULL;

		item->size = *start++;
		item->tag  = *start++;

		if ((end - start) < item->size)
			return NULL;

		item->data.longdata = start;
		start += item->size;
		return start;
	}

	item->format = HID_ITEM_FORMAT_SHORT;
	item->size = b & 3;

	switch (item->size) {
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	case 0:
		return start;
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	case 1:
		if ((end - start) < 1)
			return NULL;
		item->data.u8 = *start++;
		return start;

	case 2:
		if ((end - start) < 2)
			return NULL;
		item->data.u16 = get_unaligned_le16(start);
		start = (__u8 *)((__le16 *)start + 1);
		return start;

	case 3:
		item->size++;
		if ((end - start) < 4)
			return NULL;
		item->data.u32 = get_unaligned_le32(start);
		start = (__u8 *)((__le32 *)start + 1);
		return start;
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	}

	return NULL;
}

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static void hid_scan_input_usage(struct hid_parser *parser, u32 usage)
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{
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	struct hid_device *hid = parser->device;

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	if (usage == HID_DG_CONTACTID)
		hid->group = HID_GROUP_MULTITOUCH;
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}

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static void hid_scan_feature_usage(struct hid_parser *parser, u32 usage)
{
	if (usage == 0xff0000c5 && parser->global.report_count == 256 &&
	    parser->global.report_size == 8)
		parser->scan_flags |= HID_SCAN_FLAG_MT_WIN_8;
}

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static void hid_scan_collection(struct hid_parser *parser, unsigned type)
{
	struct hid_device *hid = parser->device;
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	int i;
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	if (((parser->global.usage_page << 16) == HID_UP_SENSOR) &&
	    type == HID_COLLECTION_PHYSICAL)
		hid->group = HID_GROUP_SENSOR_HUB;
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	if (hid->vendor == USB_VENDOR_ID_MICROSOFT &&
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	    hid->product == USB_DEVICE_ID_MS_POWER_COVER &&
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	    hid->group == HID_GROUP_MULTITOUCH)
		hid->group = HID_GROUP_GENERIC;
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	if ((parser->global.usage_page << 16) == HID_UP_GENDESK)
		for (i = 0; i < parser->local.usage_index; i++)
			if (parser->local.usage[i] == HID_GD_POINTER)
				parser->scan_flags |= HID_SCAN_FLAG_GD_POINTER;

	if ((parser->global.usage_page << 16) >= HID_UP_MSVENDOR)
		parser->scan_flags |= HID_SCAN_FLAG_VENDOR_SPECIFIC;
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}

static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
{
	__u32 data;
	int i;

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	hid_concatenate_usage_page(parser);

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	data = item_udata(item);

	switch (item->tag) {
	case HID_MAIN_ITEM_TAG_BEGIN_COLLECTION:
		hid_scan_collection(parser, data & 0xff);
		break;
	case HID_MAIN_ITEM_TAG_END_COLLECTION:
		break;
	case HID_MAIN_ITEM_TAG_INPUT:
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		/* ignore constant inputs, they will be ignored by hid-input */
		if (data & HID_MAIN_ITEM_CONSTANT)
			break;
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		for (i = 0; i < parser->local.usage_index; i++)
			hid_scan_input_usage(parser, parser->local.usage[i]);
		break;
	case HID_MAIN_ITEM_TAG_OUTPUT:
		break;
	case HID_MAIN_ITEM_TAG_FEATURE:
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		for (i = 0; i < parser->local.usage_index; i++)
			hid_scan_feature_usage(parser, parser->local.usage[i]);
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		break;
	}

	/* Reset the local parser environment */
	memset(&parser->local, 0, sizeof(parser->local));

	return 0;
}

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/*
 * Scan a report descriptor before the device is added to the bus.
 * Sets device groups and other properties that determine what driver
 * to load.
 */
static int hid_scan_report(struct hid_device *hid)
{
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	struct hid_parser *parser;
	struct hid_item item;
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	__u8 *start = hid->dev_rdesc;
	__u8 *end = start + hid->dev_rsize;
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	static int (*dispatch_type[])(struct hid_parser *parser,
				      struct hid_item *item) = {
		hid_scan_main,
		hid_parser_global,
		hid_parser_local,
		hid_parser_reserved
	};

	parser = vzalloc(sizeof(struct hid_parser));
	if (!parser)
		return -ENOMEM;
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	parser->device = hid;
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	hid->group = HID_GROUP_GENERIC;

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	/*
	 * The parsing is simpler than the one in hid_open_report() as we should
	 * be robust against hid errors. Those errors will be raised by
	 * hid_open_report() anyway.
	 */
	while ((start = fetch_item(start, end, &item)) != NULL)
		dispatch_type[item.type](parser, &item);

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	/*
	 * Handle special flags set during scanning.
	 */
	if ((parser->scan_flags & HID_SCAN_FLAG_MT_WIN_8) &&
	    (hid->group == HID_GROUP_MULTITOUCH))
		hid->group = HID_GROUP_MULTITOUCH_WIN_8;

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	/*
	 * Vendor specific handlings
	 */
	switch (hid->vendor) {
	case USB_VENDOR_ID_WACOM:
		hid->group = HID_GROUP_WACOM;
		break;
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	case USB_VENDOR_ID_SYNAPTICS:
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		if (hid->group == HID_GROUP_GENERIC)
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			if ((parser->scan_flags & HID_SCAN_FLAG_VENDOR_SPECIFIC)
			    && (parser->scan_flags & HID_SCAN_FLAG_GD_POINTER))
				/*
				 * hid-rmi should take care of them,
				 * not hid-generic
				 */
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				hid->group = HID_GROUP_RMI;
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		break;
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	}

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	kfree(parser->collection_stack);
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	vfree(parser);
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	return 0;
}

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/**
 * hid_parse_report - parse device report
 *
 * @device: hid device
 * @start: report start
 * @size: report size
 *
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 * Allocate the device report as read by the bus driver. This function should
 * only be called from parse() in ll drivers.
 */
int hid_parse_report(struct hid_device *hid, __u8 *start, unsigned size)
{
	hid->dev_rdesc = kmemdup(start, size, GFP_KERNEL);
	if (!hid->dev_rdesc)
		return -ENOMEM;
	hid->dev_rsize = size;
	return 0;
}
EXPORT_SYMBOL_GPL(hid_parse_report);

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static const char * const hid_report_names[] = {
	"HID_INPUT_REPORT",
	"HID_OUTPUT_REPORT",
	"HID_FEATURE_REPORT",
};
/**
 * hid_validate_values - validate existing device report's value indexes
 *
 * @device: hid device
 * @type: which report type to examine
 * @id: which report ID to examine (0 for first)
 * @field_index: which report field to examine
 * @report_counts: expected number of values
 *
 * Validate the number of values in a given field of a given report, after
 * parsing.
 */
struct hid_report *hid_validate_values(struct hid_device *hid,
				       unsigned int type, unsigned int id,
				       unsigned int field_index,
				       unsigned int report_counts)
{
	struct hid_report *report;

	if (type > HID_FEATURE_REPORT) {
		hid_err(hid, "invalid HID report type %u\n", type);
		return NULL;
	}

	if (id >= HID_MAX_IDS) {
		hid_err(hid, "invalid HID report id %u\n", id);
		return NULL;
	}

	/*
	 * Explicitly not using hid_get_report() here since it depends on
	 * ->numbered being checked, which may not always be the case when
	 * drivers go to access report values.
	 */
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	if (id == 0) {
		/*
		 * Validating on id 0 means we should examine the first
		 * report in the list.
		 */
		report = list_entry(
				hid->report_enum[type].report_list.next,
				struct hid_report, list);
	} else {
		report = hid->report_enum[type].report_id_hash[id];
	}
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	if (!report) {
		hid_err(hid, "missing %s %u\n", hid_report_names[type], id);
		return NULL;
	}
	if (report->maxfield <= field_index) {
		hid_err(hid, "not enough fields in %s %u\n",
			hid_report_names[type], id);
		return NULL;
	}
	if (report->field[field_index]->report_count < report_counts) {
		hid_err(hid, "not enough values in %s %u field %u\n",
			hid_report_names[type], id, field_index);
		return NULL;
	}
	return report;
}
EXPORT_SYMBOL_GPL(hid_validate_values);

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static int hid_calculate_multiplier(struct hid_device *hid,
				     struct hid_field *multiplier)
{
	int m;
	__s32 v = *multiplier->value;
	__s32 lmin = multiplier->logical_minimum;
	__s32 lmax = multiplier->logical_maximum;
	__s32 pmin = multiplier->physical_minimum;
	__s32 pmax = multiplier->physical_maximum;

	/*
	 * "Because OS implementations will generally divide the control's
	 * reported count by the Effective Resolution Multiplier, designers
	 * should take care not to establish a potential Effective
	 * Resolution Multiplier of zero."
	 * HID Usage Table, v1.12, Section 4.3.1, p31
	 */
	if (lmax - lmin == 0)
		return 1;
	/*
	 * Handling the unit exponent is left as an exercise to whoever
	 * finds a device where that exponent is not 0.
	 */
	m = ((v - lmin)/(lmax - lmin) * (pmax - pmin) + pmin);
	if (unlikely(multiplier->unit_exponent != 0)) {
		hid_warn(hid,
			 "unsupported Resolution Multiplier unit exponent %d\n",
			 multiplier->unit_exponent);
	}

	/* There are no devices with an effective multiplier > 255 */
	if (unlikely(m == 0 || m > 255 || m < -255)) {
		hid_warn(hid, "unsupported Resolution Multiplier %d\n", m);
		m = 1;
	}

	return m;
}

static void hid_apply_multiplier_to_field(struct hid_device *hid,
					  struct hid_field *field,
					  struct hid_collection *multiplier_collection,
					  int effective_multiplier)
{
	struct hid_collection *collection;
	struct hid_usage *usage;
	int i;

	/*
	 * If multiplier_collection is NULL, the multiplier applies
	 * to all fields in the report.
	 * Otherwise, it is the Logical Collection the multiplier applies to
	 * but our field may be in a subcollection of that collection.
	 */
	for (i = 0; i < field->maxusage; i++) {
		usage = &field->usage[i];

		collection = &hid->collection[usage->collection_index];
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		while (collection->parent_idx != -1 &&
		       collection != multiplier_collection)
			collection = &hid->collection[collection->parent_idx];
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		if (collection->parent_idx != -1 ||
		    multiplier_collection == NULL)
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			usage->resolution_multiplier = effective_multiplier;

	}
}

static void hid_apply_multiplier(struct hid_device *hid,
				 struct hid_field *multiplier)
{
	struct hid_report_enum *rep_enum;
	struct hid_report *rep;
	struct hid_field *field;
	struct hid_collection *multiplier_collection;
	int effective_multiplier;
	int i;

	/*
	 * "The Resolution Multiplier control must be contained in the same
	 * Logical Collection as the control(s) to which it is to be applied.
	 * If no Resolution Multiplier is defined, then the Resolution
	 * Multiplier defaults to 1.  If more than one control exists in a
	 * Logical Collection, the Resolution Multiplier is associated with
	 * all controls in the collection. If no Logical Collection is
	 * defined, the Resolution Multiplier is associated with all
	 * controls in the report."
	 * HID Usage Table, v1.12, Section 4.3.1, p30
	 *
	 * Thus, search from the current collection upwards until we find a
	 * logical collection. Then search all fields for that same parent
	 * collection. Those are the fields the multiplier applies to.
	 *
	 * If we have more than one multiplier, it will overwrite the
	 * applicable fields later.
	 */
	multiplier_collection = &hid->collection[multiplier->usage->collection_index];
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	while (multiplier_collection->parent_idx != -1 &&
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	       multiplier_collection->type != HID_COLLECTION_LOGICAL)
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		multiplier_collection = &hid->collection[multiplier_collection->parent_idx];
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	effective_multiplier = hid_calculate_multiplier(hid, multiplier);

	rep_enum = &hid->report_enum[HID_INPUT_REPORT];
	list_for_each_entry(rep, &rep_enum->report_list, list) {
		for (i = 0; i < rep->maxfield; i++) {
			field = rep->field[i];
			hid_apply_multiplier_to_field(hid, field,
						      multiplier_collection,
						      effective_multiplier);
		}
	}
}

/*
 * hid_setup_resolution_multiplier - set up all resolution multipliers
 *
 * @device: hid device
 *
 * Search for all Resolution Multiplier Feature Reports and apply their
 * value to all matching Input items. This only updates the internal struct
 * fields.
 *
 * The Resolution Multiplier is applied by the hardware. If the multiplier
 * is anything other than 1, the hardware will send pre-multiplied events
 * so that the same physical interaction generates an accumulated
 *	accumulated_value = value * * multiplier
 * This may be achieved by sending
 * - "value * multiplier" for each event, or
 * - "value" but "multiplier" times as frequently, or
 * - a combination of the above
 * The only guarantee is that the same physical interaction always generates
 * an accumulated 'value * multiplier'.
 *
 * This function must be called before any event processing and after
 * any SetRequest to the Resolution Multiplier.
 */
void hid_setup_resolution_multiplier(struct hid_device *hid)
{
	struct hid_report_enum *rep_enum;
	struct hid_report *rep;
	struct hid_usage *usage;
	int i, j;

	rep_enum = &hid->report_enum[HID_FEATURE_REPORT];
	list_for_each_entry(rep, &rep_enum->report_list, list) {
		for (i = 0; i < rep->maxfield; i++) {
			/* Ignore if report count is out of bounds. */
			if (rep->field[i]->report_count < 1)
				continue;

			for (j = 0; j < rep->field[i]->maxusage; j++) {
				usage = &rep->field[i]->usage[j];
				if (usage->hid == HID_GD_RESOLUTION_MULTIPLIER)
					hid_apply_multiplier(hid,
							     rep->field[i]);
			}
		}
	}
}
EXPORT_SYMBOL_GPL(hid_setup_resolution_multiplier);

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/**
 * hid_open_report - open a driver-specific device report
 *
 * @device: hid device
 *
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 * Parse a report description into a hid_device structure. Reports are
 * enumerated, fields are attached to these reports.
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 * 0 returned on success, otherwise nonzero error value.
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 *
 * This function (or the equivalent hid_parse() macro) should only be
 * called from probe() in drivers, before starting the device.
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 */
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int hid_open_report(struct hid_device *device)
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{
	struct hid_parser *parser;
	struct hid_item item;
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	unsigned int size;
	__u8 *start;
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	__u8 *buf;
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	__u8 *end;
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	int ret;
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	static int (*dispatch_type[])(struct hid_parser *parser,
				      struct hid_item *item) = {
		hid_parser_main,
		hid_parser_global,
		hid_parser_local,
		hid_parser_reserved
	};

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	if (WARN_ON(device->status & HID_STAT_PARSED))
		return -EBUSY;

	start = device->dev_rdesc;
	if (WARN_ON(!start))
		return -ENODEV;
	size = device->dev_rsize;

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	buf = kmemdup(start, size, GFP_KERNEL);
	if (buf == NULL)
		return -ENOMEM;

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	if (device->driver->report_fixup)
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		start = device->driver->report_fixup(device, buf, &size);
	else
		start = buf;
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	start = kmemdup(start, size, GFP_KERNEL);
	kfree(buf);
	if (start == NULL)
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		return -ENOMEM;
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	device->rdesc = start;
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	device->rsize = size;

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	parser = vzalloc(sizeof(struct hid_parser));
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	if (!parser) {
		ret = -ENOMEM;
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		goto alloc_err;
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	}
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	parser->device = device;

	end = start + size;
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	device->collection = kcalloc(HID_DEFAULT_NUM_COLLECTIONS,
				     sizeof(struct hid_collection), GFP_KERNEL);
	if (!device->collection) {
		ret = -ENOMEM;
		goto err;
	}
	device->collection_size = HID_DEFAULT_NUM_COLLECTIONS;