// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  HID support for Linux
 *
 *  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
 *  Copyright (c) 2006-2012 Jiri Kosina
 */

/*
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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>
#include <linux/vmalloc.h>
#include <linux/sched.h>
#include <linux/semaphore.h>

#include <linux/hid.h>
#include <linux/hiddev.h>
#include <linux/hid-debug.h>
#include <linux/hidraw.h>

#include "hid-ids.h"

/*
 * Version Information
 */

#define DRIVER_DESC "HID core driver"

int hid_debug = 0;
module_param_named(debug, hid_debug, int, 0600);
MODULE_PARM_DESC(debug, "toggle HID debugging messages");
EXPORT_SYMBOL_GPL(hid_debug);

static int hid_ignore_special_drivers = 0;
module_param_named(ignore_special_drivers, hid_ignore_special_drivers, int, 0600);
MODULE_PARM_DESC(ignore_special_drivers, "Ignore any special drivers and handle all devices by generic driver");

/*
 * Register a new report for a device.
 */

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

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

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

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

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

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

        return report;
}
EXPORT_SYMBOL_GPL(hid_register_report);

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

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

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

        field = kzalloc((sizeof(struct hid_field) +
                         usages * sizeof(struct hid_usage) +
                         3 * usages * sizeof(unsigned int)), GFP_KERNEL);
        if (!field)
                return NULL;

        field->index = report->maxfield++;
        report->field[field->index] = field;
        field->usage = (struct hid_usage *)(field + 1);
        field->value = (s32 *)(field->usage + usages);
        field->new_value = (s32 *)(field->value + usages);
        field->usages_priorities = (s32 *)(field->new_value + usages);
        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;
        int collection_index;

        usage = parser->local.usage[0];

        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;
        }

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

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

        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) {
                hid_err(parser->device, "collection stack underflow\n");
                return -EINVAL;
        }
        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)
{
        struct hid_collection *collection = parser->device->collection;
        int n;

        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;
        }
        return 0; /* we know nothing about this usage type */
}

/*
 * Concatenate usage which defines 16 bits or less with the
 * currently defined usage page to form a 32 bit usage
 */

static void complete_usage(struct hid_parser *parser, unsigned int index)
{
        parser->local.usage[index] &= 0xFFFF;
        parser->local.usage[index] |=
                (parser->global.usage_page & 0xFFFF) << 16;
}

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

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

        /*
         * If Usage item only includes usage id, concatenate it with
         * currently defined usage page
         */
        if (size <= 2)
                complete_usage(parser, parser->local.usage_index);

        parser->local.usage_size[parser->local.usage_index] = size;
        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;
        unsigned int usages;
        unsigned int offset;
        unsigned int i;
        unsigned int application;

        application = hid_lookup_collection(parser, HID_COLLECTION_APPLICATION);

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

        /* Handle both signed and unsigned cases properly */
        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);
                return -1;
        }

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

        /* Total size check: Allow for possible report index byte */
        if (report->size > (HID_MAX_BUFFER_SIZE - 1) << 3) {
                hid_err(parser->device, "report is too long\n");
                return -1;
        }

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

        usages = max_t(unsigned, parser->local.usage_index,
                                 parser->global.report_count);

        field = hid_register_field(report, usages);
        if (!field)
                return 0;

        field->physical = hid_lookup_collection(parser, HID_COLLECTION_PHYSICAL);
        field->logical = hid_lookup_collection(parser, HID_COLLECTION_LOGICAL);
        field->application = application;

        for (i = 0; i < usages; i++) {
                unsigned j = i;
                /* 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];
                field->usage[i].usage_index = i;
                field->usage[i].resolution_multiplier = 1;
        }

        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) {
        case 1: return item->data.u8;
        case 2: return item->data.u16;
        case 4: return item->data.u32;
        }
        return 0;
}

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

/*
 * Process a global item.
 */

static int hid_parser_global(struct hid_parser *parser, struct hid_item *item)
{
        __s32 raw_value;
        switch (item->tag) {
        case HID_GLOBAL_ITEM_TAG_PUSH:

                if (parser->global_stack_ptr == HID_GLOBAL_STACK_SIZE) {
                        hid_err(parser->device, "global environment stack overflow\n");
                        return -1;
                }

                memcpy(parser->global_stack + parser->global_stack_ptr++,
                        &parser->global, sizeof(struct hid_global));
                return 0;

        case HID_GLOBAL_ITEM_TAG_POP:

                if (!parser->global_stack_ptr) {
                        hid_err(parser->device, "global environment stack underflow\n");
                        return -1;
                }

                memcpy(&parser->global, parser->global_stack +
                        --parser->global_stack_ptr, sizeof(struct hid_global));
                return 0;

        case HID_GLOBAL_ITEM_TAG_USAGE_PAGE:
                parser->global.usage_page = item_udata(item);
                return 0;

        case HID_GLOBAL_ITEM_TAG_LOGICAL_MINIMUM:
                parser->global.logical_minimum = item_sdata(item);
                return 0;

        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;

        case HID_GLOBAL_ITEM_TAG_PHYSICAL_MINIMUM:
                parser->global.physical_minimum = item_sdata(item);
                return 0;

        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;

        case HID_GLOBAL_ITEM_TAG_UNIT_EXPONENT:
                /* 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);
                if (!(raw_value & 0xfffffff0))
                        parser->global.unit_exponent = hid_snto32(raw_value, 4);
                else
                        parser->global.unit_exponent = raw_value;
                return 0;

        case HID_GLOBAL_ITEM_TAG_UNIT:
                parser->global.unit = item_udata(item);
                return 0;

        case HID_GLOBAL_ITEM_TAG_REPORT_SIZE:
                parser->global.report_size = item_udata(item);
                if (parser->global.report_size > 256) {
                        hid_err(parser->device, "invalid report_size %d\n",
                                        parser->global.report_size);
                        return -1;
                }
                return 0;

        case HID_GLOBAL_ITEM_TAG_REPORT_COUNT:
                parser->global.report_count = item_udata(item);
                if (parser->global.report_count > HID_MAX_USAGES) {
                        hid_err(parser->device, "invalid report_count %d\n",
                                        parser->global.report_count);
                        return -1;
                }
                return 0;

        case HID_GLOBAL_ITEM_TAG_REPORT_ID:
                parser->global.report_id = item_udata(item);
                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);
                        return -1;
                }
                return 0;

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

/*
 * Process a local item.
 */

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

        data = item_udata(item);

        switch (item->tag) {
        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) {
                                hid_err(parser->device, "nested delimiters\n");
                                return -1;
                        }
                        parser->local.delimiter_depth++;
                        parser->local.delimiter_branch++;
                } else {
                        if (parser->local.delimiter_depth < 1) {
                                hid_err(parser->device, "bogus close delimiter\n");
                                return -1;
                        }
                        parser->local.delimiter_depth--;
                }
                return 0;

        case HID_LOCAL_ITEM_TAG_USAGE:

                if (parser->local.delimiter_branch > 1) {
                        dbg_hid("alternative usage ignored\n");
                        return 0;
                }

                return hid_add_usage(parser, data, item->size);

        case HID_LOCAL_ITEM_TAG_USAGE_MINIMUM:

                if (parser->local.delimiter_branch > 1) {
                        dbg_hid("alternative usage ignored\n");
                        return 0;
                }

                parser->local.usage_minimum = data;
                return 0;

        case HID_LOCAL_ITEM_TAG_USAGE_MAXIMUM:

                if (parser->local.delimiter_branch > 1) {
                        dbg_hid("alternative usage ignored\n");
                        return 0;
                }

                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;
                        }
                }

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

/*
 * 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_last_usage_page(struct hid_parser *parser)
{
        int i;
        unsigned int usage_page;
        unsigned int current_page;

        if (!parser->local.usage_index)
                return;

        usage_page = parser->global.usage_page;

        /*
         * Concatenate usage page again only if last declared Usage Page
         * has not been already used in previous usages concatenation
         */
        for (i = parser->local.usage_index - 1; i >= 0; i--) {
                if (parser->local.usage_size[i] > 2)
                        /* Ignore extended usages */
                        continue;

                current_page = parser->local.usage[i] >> 16;
                if (current_page == usage_page)
                        break;

                complete_usage(parser, i);
        }
}

/*
 * Process a main item.
 */

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

        hid_concatenate_last_usage_page(parser);

        data = item_udata(item);

        switch (item->tag) {
        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:
                hid_warn(parser->device, "unknown main item tag 0x%x\n", item->tag);
                ret = 0;
        }

        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)
{
        dbg_hid("reserved item type, tag 0x%x\n", item->tag);
        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;

        kfree(report->field_entries);

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

/*
 * Close report. This function returns the device
 * state to the point prior to hid_open_report().
 */
static void hid_close_report(struct hid_device *device)
{
        unsigned i, j;

        for (i = 0; i < HID_REPORT_TYPES; i++) {
                struct hid_report_enum *report_enum = device->report_enum + i;

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

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

        kfree(device->collection);
        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)
{
        struct hid_device *hid = to_hid_device(dev);

        hid_close_report(hid);
        kfree(hid->dev_rdesc);
        kfree(hid);
}

/*
 * 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) {
        case 0:
                return start;

        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;
        }

        return NULL;
}

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

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

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;

        if (usage == 0xff0000c6 && parser->global.report_count == 1 &&
            parser->global.report_size == 8)
                parser->scan_flags |= HID_SCAN_FLAG_MT_WIN_8;
}

static void hid_scan_collection(struct hid_parser *parser, unsigned type)
{
        struct hid_device *hid = parser->device;
        int i;

        if (((parser->global.usage_page << 16) == HID_UP_SENSOR) &&
            type == HID_COLLECTION_PHYSICAL)
                hid->group = HID_GROUP_SENSOR_HUB;

        if (hid->vendor == USB_VENDOR_ID_MICROSOFT &&
            hid->product == USB_DEVICE_ID_MS_POWER_COVER &&
            hid->group == HID_GROUP_MULTITOUCH)
                hid->group = HID_GROUP_GENERIC;

        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;

        if ((parser->global.usage_page << 16) == HID_UP_GOOGLEVENDOR)
                for (i = 0; i < parser->local.usage_index; i++)
                        if (parser->local.usage[i] ==
                                        (HID_UP_GOOGLEVENDOR | 0x0001))
                                parser->device->group =
                                        HID_GROUP_VIVALDI;
}

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

        hid_concatenate_last_usage_page(parser);

        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:
                /* ignore constant inputs, they will be ignored by hid-input */
                if (data & HID_MAIN_ITEM_CONSTANT)
                        break;
                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:
                for (i = 0; i < parser->local.usage_index; i++)
                        hid_scan_feature_usage(parser, parser->local.usage[i]);
                break;
        }

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

        return 0;
}

/*
 * 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)
{
        struct hid_parser *parser;
        struct hid_item item;
        __u8 *start = hid->dev_rdesc;
        __u8 *end = start + hid->dev_rsize;
        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;

        parser->device = hid;
        hid->group = HID_GROUP_GENERIC;

        /*
         * 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);

        /*
         * 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;

        /*
         * Vendor specific handlings
         */
        switch (hid->vendor) {
        case USB_VENDOR_ID_WACOM:
                hid->group = HID_GROUP_WACOM;
                break;
        case USB_VENDOR_ID_SYNAPTICS:
                if (hid->group == HID_GROUP_GENERIC)
                        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
                                 */
                                hid->group = HID_GROUP_RMI;
                break;
        }

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

/**
 * hid_parse_report - parse device report
 *
 * @hid: hid device
 * @start: report start
 * @size: report size
 *
 * 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);

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
 *
 * @hid: 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.
         */
        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];

        }
        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);

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];
                while (collection->parent_idx != -1 &&
                       collection != multiplier_collection)
                        collection = &hid->collection[collection->parent_idx];

                if (collection->parent_idx != -1 ||
                    multiplier_collection == NULL)
                        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];
        while (multiplier_collection->parent_idx != -1 &&
               multiplier_collection->type != HID_COLLECTION_LOGICAL)
                multiplier_collection = &hid->collection[multiplier_collection->parent_idx];

        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);

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

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

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

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

        if (device->driver->report_fixup)
                start = device->driver->report_fixup(device, buf, &size);
        else
                start = buf;

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

        device->rdesc = start;
        device->rsize = size;

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

        parser->device = device;

        end = start + size;

        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;

        ret = -EINVAL;
        while ((next = fetch_item(start, end, &item)) != NULL) {
                start = next;

                if (item.format != HID_ITEM_FORMAT_SHORT) {
                        hid_err(device, "unexpected long global item\n");
                        goto err;
                }

                if (dispatch_type[item.type](parser, &item)) {
                        hid_err(device, "item %u %u %u %u parsing failed\n",
                                item.format, (unsigned)item.size,
                                (unsigned)item.type, (unsigned)item.tag);
                        goto err;
                }

                if (start == end) {
                        if (parser->collection_stack_ptr) {
                                hid_err(device, "unbalanced collection at end of report description\n");
                                goto err;
                        }
                        if (parser->local.delimiter_depth) {
                                hid_err(device, "unbalanced delimiter at end of report description\n");
                                goto err;
                        }

                        /*
                         * fetch initial values in case the device's
                         * default multiplier isn't the recommended 1
                         */
                        hid_setup_resolution_multiplier(device);

                        kfree(parser->collection_stack);
                        vfree(parser);
                        device->status |= HID_STAT_PARSED;

                        return 0;
                }
        }

        hid_err(device, "item fetching failed at offset %u/%u\n",
                size - (unsigned int)(end - start), size);
err:
        kfree(parser->collection_stack);
alloc_err:
        vfree(parser);
        hid_close_report(device);
        return ret;
}
EXPORT_SYMBOL_GPL(hid_open_report);

/*
 * Convert a signed n-bit integer to signed 32-bit integer. Common
 * cases are done through the compiler, the screwed things has to be
 * done by hand.
 */

static s32 snto32(__u32 value, unsigned n)
{
        if (!value || !n)
                return 0;

        switch (n) {
        case 8:  return ((__s8)value);
        case 16: return ((__s16)value);
        case 32: return ((__s32)value);
        }
        return value & (1 << (n - 1)) ? value | (~0U << n) : value;
}

s32 hid_snto32(__u32 value, unsigned n)
{
        return snto32(value, n);
}
EXPORT_SYMBOL_GPL(hid_snto32);

/*
 * Convert a signed 32-bit integer to a signed n-bit integer.
 */

static u32 s32ton(__s32 value, unsigned n)
{
        s32 a = value >> (n - 1);
        if (a && a != -1)
                return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1;
        return value & ((1 << n) - 1);
}

/*
 * Extract/implement a data field from/to a little endian report (bit array).
 *
 * Code sort-of follows HID spec:
 *     http://www.usb.org/developers/hidpage/HID1_11.pdf
 *
 * While the USB HID spec allows unlimited length bit fields in "report
 * descriptors", most devices never use more than 16 bits.
 * One model of UPS is claimed to report "LINEV" as a 32-bit field.
 * Search linux-kernel and linux-usb-devel archives for "hid-core extract".
 */

static u32 __extract(u8 *report, unsigned offset, int n)
{
        unsigned int idx = offset / 8;
        unsigned int bit_nr = 0;
        unsigned int bit_shift = offset % 8;
        int bits_to_copy = 8 - bit_shift;
        u32 value = 0;
        u32 mask = n < 32 ? (1U << n) - 1 : ~0U;

        while (n > 0) {
                value |= ((u32)report[idx] >> bit_shift) << bit_nr;
                n -= bits_to_copy;
                bit_nr += bits_to_copy;
                bits_to_copy = 8;
                bit_shift = 0;
                idx++;
        }

        return value & mask;
}

u32 hid_field_extract(const struct hid_device *hid, u8 *report,
                        unsigned offset, unsigned n)
{
        if (n > 32) {
                hid_warn_once(hid, "%s() called with n (%d) > 32! (%s)\n",
                              __func__, n, current->comm);
                n = 32;
        }

        return __extract(report, offset, n);
}
EXPORT_SYMBOL_GPL(hid_field_extract);

/*
 * "implement" : set bits in a little endian bit stream.
 * Same concepts as "extract" (see comments above).
 * The data mangled in the bit stream remains in little endian
 * order the whole time. It make more sense to talk about
 * endianness of register values by considering a register
 * a "cached" copy of the little endian bit stream.
 */

static void __implement(u8 *report, unsigned offset, int n, u32 value)
{
        unsigned int idx = offset / 8;
        unsigned int bit_shift = offset % 8;
        int bits_to_set = 8 - bit_shift;

        while (n - bits_to_set >= 0) {
                report[idx] &= ~(0xff << bit_shift);
                report[idx] |= value << bit_shift;
                value >>= bits_to_set;
                n -= bits_to_set;
                bits_to_set = 8;
                bit_shift = 0;
                idx++;
        }

        /* last nibble */
        if (n) {
                u8 bit_mask = ((1U << n) - 1);
                report[idx] &= ~(bit_mask << bit_shift);
                report[idx] |= value << bit_shift;
        }
}

static void implement(const struct hid_device *hid, u8 *report,
                      unsigned offset, unsigned n, u32 value)
{
        if (unlikely(n > 32)) {
                hid_warn(hid, "%s() called with n (%d) > 32! (%s)\n",
                         __func__, n, current->comm);
                n = 32;
        } else if (n < 32) {
                u32 m = (1U << n) - 1;

                if (unlikely(value > m)) {
                        hid_warn(hid,
                                 "%s() called with too large value %d (n: %d)! (%s)\n",
                                 __func__, value, n, current->comm);
                        WARN_ON(1);
                        value &= m;
                }
        }

        __implement(report, offset, n, value);
}

/*
 * Search an array for a value.
 */

static int search(__s32 *array, __s32 value, unsigned n)
{
        while (n--) {
                if (*array++ == value)
                        return 0;
        }
        return -1;
}

/**
 * hid_match_report - check if driver's raw_event should be called
 *
 * @hid: hid device
 * @report: hid report to match against
 *
 * compare hid->driver->report_table->report_type to report->type
 */
static int hid_match_report(struct hid_device *hid, struct hid_report *report)
{
        const struct hid_report_id *id = hid->driver->report_table;

        if (!id) /* NULL means all */
                return 1;

        for (; id->report_type != HID_TERMINATOR; id++)
                if (id->report_type == HID_ANY_ID ||
                                id->report_type == report->type)
                        return 1;
        return 0;
}

/**
 * hid_match_usage - check if driver's event should be called
 *
 * @hid: hid device
 * @usage: usage to match against
 *
 * compare hid->driver->usage_table->usage_{type,code} to
 * usage->usage_{type,code}
 */
static int hid_match_usage(struct hid_device *hid, struct hid_usage *usage)
{
        const struct hid_usage_id *id = hid->driver->usage_table;

        if (!id) /* NULL means all */
                return 1;

        for (; id->usage_type != HID_ANY_ID - 1; id++)
                if ((id->usage_hid == HID_ANY_ID ||
                                id->usage_hid == usage->hid) &&
                                (id->usage_type == HID_ANY_ID ||
                                id->usage_type == usage->type) &&
                                (id->usage_code == HID_ANY_ID ||
                                 id->usage_code == usage->code))
                        return 1;
        return 0;
}

static void hid_process_event(struct hid_device *hid, struct hid_field *field,
                struct hid_usage *usage, __s32 value, int interrupt)
{
        struct hid_driver *hdrv = hid->driver;
        int ret;

        if (!list_empty(&hid->debug_list))
                hid_dump_input(hid, usage, value);

        if (hdrv && hdrv->event && hid_match_usage(hid, usage)) {
                ret = hdrv->event(hid, field, usage, value);
                if (ret != 0) {
                        if (ret < 0)
                                hid_err(hid, "%s's event failed with %d\n",
                                                hdrv->name, ret);
                        return;
                }
        }

        if (hid->claimed & HID_CLAIMED_INPUT)
                hidinput_hid_event(hid, field, usage, value);
        if (hid->claimed & HID_CLAIMED_HIDDEV && interrupt && hid->hiddev_hid_event)
                hid->hiddev_hid_event(hid, field, usage, value);
}

/*
 * Checks if the given value is valid within this field
 */
static inline int hid_array_value_is_valid(struct hid_field *field,
                                           __s32 value)
{
        __s32 min = field->logical_minimum;

        /*
         * Value needs to be between logical min and max, and
         * (value - min) is used as an index in the usage array.
         * This array is of size field->maxusage
         */
        return value >= min &&
               value <= field->logical_maximum &&
               value - min < field->maxusage;
}

/*
 * Fetch the field from the data. The field content is stored for next
 * report processing (we do differential reporting to the layer).
 */
static void hid_input_fetch_field(struct hid_device *hid,
                                  struct hid_field *field,
                                  __u8 *data)
{
        unsigned n;
        unsigned count = field->report_count;
        unsigned offset = field->report_offset;
        unsigned size = field->report_size;
        __s32 min = field->logical_minimum;
        __s32 *value;

        value = field->new_value;
        memset(value, 0, count * sizeof(__s32));
        field->ignored = false;

        for (n = 0; n < count; n++) {

                value[n] = min < 0 ?
                        snto32(hid_field_extract(hid, data, offset + n * size,
                               size), size) :
                        hid_field_extract(hid, data, offset + n * size, size);

                /* Ignore report if ErrorRollOver */
                if (!(field->flags & HID_MAIN_ITEM_VARIABLE) &&
                    hid_array_value_is_valid(field, value[n]) &&
                    field->usage[value[n] - min].hid == HID_UP_KEYBOARD + 1) {
                        field->ignored = true;
                        return;
                }
        }
}

/*
 * Process a received variable field.
 */

static void hid_input_var_field(struct hid_device *hid,
                                struct hid_field *field,
                                int interrupt)
{
        unsigned int count = field->report_count;
        __s32 *value = field->new_value;
        unsigned int n;

        for (n = 0; n < count; n++)
                hid_process_event(hid,
                                  field,
                                  &field->usage[n],
                                  value[n],
                                  interrupt);

        memcpy(field->value, value, count * sizeof(__s32));
}

/*
 * Process a received array field. The field content is stored for
 * next report processing (we do differential reporting to the layer).
 */

static void hid_input_array_field(struct hid_device *hid,
                                  struct hid_field *field,
                                  int interrupt)
{
        unsigned int n;
        unsigned int count = field->report_count;
        __s32 min = field->logical_minimum;
        __s32 *value;

        value = field->new_value;

        /* ErrorRollOver */
        if (field->ignored)
                return;

        for (n = 0; n < count; n++) {
                if (hid_array_value_is_valid(field, field->value[n]) &&
                    search(value, field->value[n], count))
                        hid_process_event(hid,
                                          field,
                                          &field->usage[field->value[n] - min],
                                          0,
                                          interrupt);

                if (hid_array_value_is_valid(field, value[n]) &&
                    search(field->value, value[n], count))
                        hid_process_event(hid,
                                          field,
                                          &field->usage[value[n] - min],
                                          1,
                                          interrupt);
        }

        memcpy(field->value, value, count * sizeof(__s32));
}

/*
 * Analyse a received report, and fetch the data from it. The field
 * content is stored for next report processing (we do differential
 * reporting to the layer).
 */
static void hid_process_report(struct hid_device *hid,
                               struct hid_report *report,
                               __u8 *data,
                               int interrupt)
{
        unsigned int a;
        struct hid_field_entry *entry;
        struct hid_field *field;

        /* first retrieve all incoming values in data */
        for (a = 0; a < report->maxfield; a++)
                hid_input_fetch_field(hid, field = report->field[a], data);

        if (!list_empty(&report->field_entry_list)) {
                /* INPUT_REPORT, we have a priority list of fields */
                list_for_each_entry(entry,
                                    &report->field_entry_list,
                                    list) {
                        field = entry->field;

                        if (field->flags & HID_MAIN_ITEM_VARIABLE)
                                hid_process_event(hid,
                                                  field,
                                                  &field->usage[entry->index],
                                                  field->new_value[entry->index],
                                                  interrupt);
                        else
                                hid_input_array_field(hid, field, interrupt);
                }

                /* we need to do the memcpy at the end for var items */
                for (a = 0; a < report->maxfield; a++) {
                        field = report->field[a];

                        if (field->flags & HID_MAIN_ITEM_VARIABLE)
                                memcpy(field->value, field->new_value,
                                       field->report_count * sizeof(__s32));
                }
        } else {
                /* FEATURE_REPORT, regular processing */
                for (a = 0; a < report->maxfield; a++) {
                        field = report->field[a];

                        if (field->flags & HID_MAIN_ITEM_VARIABLE)
                                hid_input_var_field(hid, field, interrupt);
                        else
                                hid_input_array_field(hid, field, interrupt);
                }
        }
}

/*
 * Insert a given usage_index in a field in the list
 * of processed usages in the report.
 *
 * The elements of lower priority score are processed
 * first.
 */
static void __hid_insert_field_entry(struct hid_device *hid,
                                     struct hid_report *report,
                                     struct hid_field_entry *entry,
                                     struct hid_field *field,
                                     unsigned int usage_index)
{
        struct hid_field_entry *next;

        entry->field = field;
        entry->index = usage_index;
        entry->priority = field->usages_priorities[usage_index];

        /* insert the element at the correct position */
        list_for_each_entry(next,
                            &report->field_entry_list,
                            list) {
                /*
                 * the priority of our element is strictly higher
                 * than the next one, insert it before
                 */
                if (entry->priority > next->priority) {
                        list_add_tail(&entry->list, &next->list);
                        return;
                }
        }

        /* lowest priority score: insert at the end */
        list_add_tail(&entry->list, &report->field_entry_list);
}

static void hid_report_process_ordering(struct hid_device *hid,
                                        struct hid_report *report)
{
        struct hid_field *field;
        struct hid_field_entry *entries;
        unsigned int a, u, usages;
        unsigned int count = 0;

        /* count the number of individual fields in the report */
        for (a = 0; a < report->maxfield; a++) {
                field = report->field[a];

                if (field->flags & HID_MAIN_ITEM_VARIABLE)
                        count += field->report_count;
                else
                        count++;
        }

        /* allocate the memory to process the fields */
        entries = kcalloc(count, sizeof(*entries), GFP_KERNEL);
        if (!entries)
                return;

        report->field_entries = entries;

        /*
         * walk through all fields in the report and
         * store them by priority order in report->field_entry_list
         *
         * - Var elements are individualized (field + usage_index)
         * - Arrays are taken as one, we can not chose an order for them
         */
        usages = 0;
        for (a = 0; a < report->maxfield; a++) {
                field = report->field[a];

                if (field->flags & HID_MAIN_ITEM_VARIABLE) {
                        for (u = 0; u < field->report_count; u++) {
                                __hid_insert_field_entry(hid, report,
                                                         &entries[usages],
                                                         field, u);
                                usages++;
                        }
                } else {
                        __hid_insert_field_entry(hid, report, &entries[usages],
                                                 field, 0);
                        usages++;
                }
        }
}

static void hid_process_ordering(struct hid_device *hid)
{
        struct hid_report *report;
        struct hid_report_enum *report_enum = &hid->report_enum[HID_INPUT_REPORT];

        list_for_each_entry(report, &report_enum->report_list, list)
                hid_report_process_ordering(hid, report);
}

/*
 * Output the field into the report.
 */

static void hid_output_field(const struct hid_device *hid,
                             struct hid_field *field, __u8 *data)
{
        unsigned count = field->report_count;
        unsigned offset = field->report_offset;
        unsigned size = field->report_size;
        unsigned n;

        for (n = 0; n < count; n++) {
                if (field->logical_minimum < 0) /* signed values */
                        implement(hid, data, offset + n * size, size,
                                  s32ton(field->value[n], size));
                else                            /* unsigned values */
                        implement(hid, data, offset + n * size, size,
                                  field->value[n]);
        }
}

/*
 * Compute the size of a report.
 */
static size_t hid_compute_report_size(struct hid_report *report)
{
        if (report->size)
                return ((report->size - 1) >> 3) + 1;

        return 0;
}

/*
 * Create a report. 'data' has to be allocated using
 * hid_alloc_report_buf() so that it has proper size.
 */

void hid_output_report(struct hid_report *report, __u8 *data)
{
        unsigned n;

        if (report->id > 0)
                *data++ = report->id;

        memset(data, 0, hid_compute_report_size(report));
        for (n = 0; n < report->maxfield; n++)
                hid_output_field(report->device, report->field[n], data);
}
EXPORT_SYMBOL_GPL(hid_output_report);

/*
 * Allocator for buffer that is going to be passed to hid_output_report()
 */
u8 *hid_alloc_report_buf(struct hid_report *report, gfp_t flags)
{
        /*
         * 7 extra bytes are necessary to achieve proper functionality
         * of implement() working on 8 byte chunks
         */

        u32 len = hid_report_len(report) + 7;

        return kmalloc(len, flags);
}
EXPORT_SYMBOL_GPL(hid_alloc_report_buf);

/*
 * Set a field value. The report this field belongs to has to be
 * created and transferred to the device, to set this value in the
 * device.
 */

int hid_set_field(struct hid_field *field, unsigned offset, __s32 value)
{
        unsigned size;

        if (!field)
                return -1;

        size = field->report_size;

        hid_dump_input(field->report->device, field->usage + offset, value);

        if (offset >= field->report_count) {
                hid_err(field->report->device, "offset (%d) exceeds report_count (%d)\n",
                                offset, field->report_count);
                return -1;
        }
        if (field->logical_minimum < 0) {
                if (value != snto32(s32ton(value, size), size)) {
                        hid_err(field->report->device, "value %d is out of range\n", value);
                        return -1;
                }
        }
        field->value[offset] = value;
        return 0;
}
EXPORT_SYMBOL_GPL(hid_set_field);

static struct hid_report *hid_get_report(struct hid_report_enum *report_enum,
                const u8 *data)
{
        struct hid_report *report;
        unsigned int n = 0;     /* Normally report number is 0 */

        /* Device uses numbered reports, data[0] is report number */
        if (report_enum->numbered)
                n = *data;

        report = report_enum->report_id_hash[n];
        if (report == NULL)
                dbg_hid("undefined report_id %u received\n", n);

        return report;
}

/*
 * Implement a generic .request() callback, using .raw_request()
 * DO NOT USE in hid drivers directly, but through hid_hw_request instead.
 */
int __hid_request(struct hid_device *hid, struct hid_report *report,
                int reqtype)
{
        char *buf;
        int ret;
        u32 len;

        buf = hid_alloc_report_buf(report, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        len = hid_report_len(report);

        if (reqtype == HID_REQ_SET_REPORT)
                hid_output_report(report, buf);

        ret = hid->ll_driver->raw_request(hid, report->id, buf, len,
                                          report->type, reqtype);
        if (ret < 0) {
                dbg_hid("unable to complete request: %d\n", ret);
                goto out;
        }

        if (reqtype == HID_REQ_GET_REPORT)
                hid_input_report(hid, report->type, buf, ret, 0);

        ret = 0;

out:
        kfree(buf);
        return ret;
}
EXPORT_SYMBOL_GPL(__hid_request);

int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size,
                int interrupt)
{
        struct hid_report_enum *report_enum = hid->report_enum + type;
        struct hid_report *report;
        struct hid_driver *hdrv;
        u32 rsize, csize = size;
        u8 *cdata = data;
        int ret = 0;

        report = hid_get_report(report_enum, data);
        if (!report)
                goto out;

        if (report_enum->numbered) {
                cdata++;
                csize--;
        }

        rsize = hid_compute_report_size(report);

        if (report_enum->numbered && rsize >= HID_MAX_BUFFER_SIZE)
                rsize = HID_MAX_BUFFER_SIZE - 1;
        else if (rsize > HID_MAX_BUFFER_SIZE)
                rsize = HID_MAX_BUFFER_SIZE;

        if (csize < rsize) {
                dbg_hid("report %d is too short, (%d < %d)\n", report->id,
                                csize, rsize);
                memset(cdata + csize, 0, rsize - csize);
        }

        if ((hid->claimed & HID_CLAIMED_HIDDEV) && hid->hiddev_report_event)
                hid->hiddev_report_event(hid, report);
        if (hid->claimed & HID_CLAIMED_HIDRAW) {
                ret = hidraw_report_event(hid, data, size);
                if (ret)
                        goto out;
        }

        if (hid->claimed != HID_CLAIMED_HIDRAW && report->maxfield) {
                hid_process_report(hid, report, cdata, interrupt);
                hdrv = hid->driver;
                if (hdrv && hdrv->report)

                        hdrv->report(hid, report);
        }

        if (hid->claimed & HID_CLAIMED_INPUT)
                hidinput_report_event(hid, report);
out:
        return ret;
}
EXPORT_SYMBOL_GPL(hid_report_raw_event);

/**
 * hid_input_report - report data from lower layer (usb, bt...)
 *
 * @hid: hid device
 * @type: HID report type (HID_*_REPORT)
 * @data: report contents
 * @size: size of data parameter
 * @interrupt: distinguish between interrupt and control transfers
 *
 * This is data entry for lower layers.
 */
int hid_input_report(struct hid_device *hid, int type, u8 *data, u32 size, int interrupt)
{
        struct hid_report_enum *report_enum;
        struct hid_driver *hdrv;
        struct hid_report *report;
        int ret = 0;

        if (!hid)
                return -ENODEV;

        if (down_trylock(&hid->driver_input_lock))
                return -EBUSY;

        if (!hid->driver) {
                ret = -ENODEV;
                goto unlock;
        }
        report_enum = hid->report_enum + type;
        hdrv = hid->driver;

        if (!size) {
                dbg_hid("empty report\n");
                ret = -1;
                goto unlock;
        }

        /* Avoid unnecessary overhead if debugfs is disabled */
        if (!list_empty(&hid->debug_list))
                hid_dump_report(hid, type, data, size);

        report = hid_get_report(report_enum, data);

        if (!report) {
                ret = -1;
                goto unlock;
        }

        if (hdrv && hdrv->raw_event && hid_match_report(hid, report)) {
                ret = hdrv->raw_event(hid, report, data, size);
                if (ret < 0)
                        goto unlock;
        }

        ret = hid_report_raw_event(hid, type, data, size, interrupt);

unlock:
        up(&hid->driver_input_lock);
        return ret;
}
EXPORT_SYMBOL_GPL(hid_input_report);

bool hid_match_one_id(const struct hid_device *hdev,
                      const struct hid_device_id *id)
{
        return (id->bus == HID_BUS_ANY || id->bus == hdev->bus) &&
                (id->group == HID_GROUP_ANY || id->group == hdev->group) &&
                (id->vendor == HID_ANY_ID || id->vendor == hdev->vendor) &&
                (id->product == HID_ANY_ID || id->product == hdev->product);
}

const struct hid_device_id *hid_match_id(const struct hid_device *hdev,
                const struct hid_device_id *id)
{
        for (; id->bus; id++)
                if (hid_match_one_id(hdev, id))
                        return id;

        return NULL;
}

static const struct hid_device_id hid_hiddev_list[] = {
        { HID_USB_DEVICE(USB_VENDOR_ID_MGE, USB_DEVICE_ID_MGE_UPS) },
        { HID_USB_DEVICE(USB_VENDOR_ID_MGE, USB_DEVICE_ID_MGE_UPS1) },
        { }
};

static bool hid_hiddev(struct hid_device *hdev)
{
        return !!hid_match_id(hdev, hid_hiddev_list);
}


static ssize_t
read_report_descriptor(struct file *filp, struct kobject *kobj,
                struct bin_attribute *attr,
                char *buf, loff_t off, size_t count)
{
        struct device *dev = kobj_to_dev(kobj);
        struct hid_device *hdev = to_hid_device(dev);

        if (off >= hdev->rsize)
                return 0;

        if (off + count > hdev->rsize)
                count = hdev->rsize - off;

        memcpy(buf, hdev->rdesc + off, count);

        return count;
}

static ssize_t
show_country(struct device *dev, struct device_attribute *attr,
                char *buf)
{
        struct hid_device *hdev = to_hid_device(dev);

        return sprintf(buf, "%02x\n", hdev->country & 0xff);
}

static struct bin_attribute dev_bin_attr_report_desc = {
        .attr = { .name = "report_descriptor", .mode = 0444 },
        .read = read_report_descriptor,
        .size = HID_MAX_DESCRIPTOR_SIZE,
};

static const struct device_attribute dev_attr_country = {
        .attr = { .name = "country", .mode = 0444 },
        .show = show_country,
};

int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
{
        static const char *types[] = { "Device", "Pointer", "Mouse", "Device",
                "Joystick", "Gamepad", "Keyboard", "Keypad",
                "Multi-Axis Controller"
        };
        const char *type, *bus;
        char buf[64] = "";
        unsigned int i;
        int len;
        int ret;

        if (hdev->quirks & HID_QUIRK_HIDDEV_FORCE)
                connect_mask |= (HID_CONNECT_HIDDEV_FORCE | HID_CONNECT_HIDDEV);
        if (hdev->quirks & HID_QUIRK_HIDINPUT_FORCE)
                connect_mask |= HID_CONNECT_HIDINPUT_FORCE;
        if (hdev->bus != BUS_USB)
                connect_mask &= ~HID_CONNECT_HIDDEV;
        if (hid_hiddev(hdev))
                connect_mask |= HID_CONNECT_HIDDEV_FORCE;

        if ((connect_mask & HID_CONNECT_HIDINPUT) && !hidinput_connect(hdev,
                                connect_mask & HID_CONNECT_HIDINPUT_FORCE))
                hdev->claimed |= HID_CLAIMED_INPUT;

        if ((connect_mask & HID_CONNECT_HIDDEV) && hdev->hiddev_connect &&
                        !hdev->hiddev_connect(hdev,
                                connect_mask & HID_CONNECT_HIDDEV_FORCE))
                hdev->claimed |= HID_CLAIMED_HIDDEV;
        if ((connect_mask & HID_CONNECT_HIDRAW) && !hidraw_connect(hdev))
                hdev->claimed |= HID_CLAIMED_HIDRAW;

        if (connect_mask & HID_CONNECT_DRIVER)
                hdev->claimed |= HID_CLAIMED_DRIVER;

        /* Drivers with the ->raw_event callback set are not required to connect
         * to any other listener. */
        if (!hdev->claimed && !hdev->driver->raw_event) {
                hid_err(hdev, "device has no listeners, quitting\n");
                return -ENODEV;
        }

        hid_process_ordering(hdev);

        if ((hdev->claimed & HID_CLAIMED_INPUT) &&
                        (connect_mask & HID_CONNECT_FF) && hdev->ff_init)
                hdev->ff_init(hdev);

        len = 0;
        if (hdev->claimed & HID_CLAIMED_INPUT)
                len += sprintf(buf + len, "input");
        if (hdev->claimed & HID_CLAIMED_HIDDEV)
                len += sprintf(buf + len, "%shiddev%d", len ? "," : "",
                                ((struct hiddev *)hdev->hiddev)->minor);
        if (hdev->claimed & HID_CLAIMED_HIDRAW)
                len += sprintf(buf + len, "%shidraw%d", len ? "," : "",
                                ((struct hidraw *)hdev->hidraw)->minor);

        type = "Device";
        for (i = 0; i < hdev->maxcollection; i++) {
                struct hid_collection *col = &hdev->collection[i];
                if (col->type == HID_COLLECTION_APPLICATION &&
                   (col->usage & HID_USAGE_PAGE) == HID_UP_GENDESK &&
                   (col->usage & 0xffff) < ARRAY_SIZE(types)) {
                        type = types[col->usage & 0xffff];
                        break;
                }
        }

        switch (hdev->bus) {
        case BUS_USB:
                bus = "USB";
                break;
        case BUS_BLUETOOTH:
                bus = "BLUETOOTH";
                break;
        case BUS_I2C:
                bus = "I2C";
                break;
        case BUS_VIRTUAL:
                bus = "VIRTUAL";
                break;
        case BUS_INTEL_ISHTP:
        case BUS_AMD_SFH:
                bus = "SENSOR HUB";
                break;
        default:
                bus = "<UNKNOWN>";
        }

        ret = device_create_file(&hdev->dev, &dev_attr_country);
        if (ret)
                hid_warn(hdev,
                         "can't create sysfs country code attribute err: %d\n", ret);

        hid_info(hdev, "%s: %s HID v%x.%02x %s [%s] on %s\n",
                 buf, bus, hdev->version >> 8, hdev->version & 0xff,
                 type, hdev->name, hdev->phys);

        return 0;
}
EXPORT_SYMBOL_GPL(hid_connect);

void hid_disconnect(struct hid_device *hdev)
{
        device_remove_file(&hdev->dev, &dev_attr_country);
        if (hdev->claimed & HID_CLAIMED_INPUT)
                hidinput_disconnect(hdev);
        if (hdev->claimed & HID_CLAIMED_HIDDEV)
                hdev->hiddev_disconnect(hdev);
        if (hdev->claimed & HID_CLAIMED_HIDRAW)
                hidraw_disconnect(hdev);
        hdev->claimed = 0;
}
EXPORT_SYMBOL_GPL(hid_disconnect);

/**
 * hid_hw_start - start underlying HW
 * @hdev: hid device
 * @connect_mask: which outputs to connect, see HID_CONNECT_*
 *
 * Call this in probe function *after* hid_parse. This will setup HW
 * buffers and start the device (if not defeirred to device open).
 * hid_hw_stop must be called if this was successful.
 */
int hid_hw_start(struct hid_device *hdev, unsigned int connect_mask)
{
        int error;

        error = hdev->ll_driver->start(hdev);
        if (error)
                return error;

        if (connect_mask) {
                error = hid_connect(hdev, connect_mask);
                if (error) {
                        hdev->ll_driver->stop(hdev);
                        return error;
                }
        }

        return 0;
}
EXPORT_SYMBOL_GPL(hid_hw_start);

/**
 * hid_hw_stop - stop underlying HW
 * @hdev: hid device
 *
 * This is usually called from remove function or from probe when something
 * failed and hid_hw_start was called already.
 */
void hid_hw_stop(struct hid_device *hdev)
{
        hid_disconnect(hdev);
        hdev->ll_driver->stop(hdev);
}
EXPORT_SYMBOL_GPL(hid_hw_stop);

/**
 * hid_hw_open - signal underlying HW to start delivering events
 * @hdev: hid device
 *
 * Tell underlying HW to start delivering events from the device.
 * This function should be called sometime after successful call
 * to hid_hw_start().
 */
int hid_hw_open(struct hid_device *hdev)
{
        int ret;

        ret = mutex_lock_killable(&hdev->ll_open_lock);
        if (ret)
                return ret;

        if (!hdev->ll_open_count++) {
                ret = hdev->ll_driver->open(hdev);
                if (ret)
                        hdev->ll_open_count--;
        }

        mutex_unlock(&hdev->ll_open_lock);
        return ret;
}
EXPORT_SYMBOL_GPL(hid_hw_open);

/**
 * hid_hw_close - signal underlaying HW to stop delivering events
 *
 * @hdev: hid device
 *
 * This function indicates that we are not interested in the events
 * from this device anymore. Delivery of events may or may not stop,
 * depending on the number of users still outstanding.
 */
void hid_hw_close(struct hid_device *hdev)
{
        mutex_lock(&hdev->ll_open_lock);
        if (!--hdev->ll_open_count)
                hdev->ll_driver->close(hdev);
        mutex_unlock(&hdev->ll_open_lock);
}
EXPORT_SYMBOL_GPL(hid_hw_close);

/**
 * hid_hw_request - send report request to device
 *
 * @hdev: hid device
 * @report: report to send
 * @reqtype: hid request type
 */
void hid_hw_request(struct hid_device *hdev,
                    struct hid_report *report, int reqtype)
{
        if (hdev->ll_driver->request)
                return hdev->ll_driver->request(hdev, report, reqtype);

        __hid_request(hdev, report, reqtype);
}
EXPORT_SYMBOL_GPL(hid_hw_request);

/**
 * hid_hw_raw_request - send report request to device
 *
 * @hdev: hid device
 * @reportnum: report ID
 * @buf: in/out data to transfer
 * @len: length of buf
 * @rtype: HID report type
 * @reqtype: HID_REQ_GET_REPORT or HID_REQ_SET_REPORT
 *
 * Return: count of data transferred, negative if error
 *
 * Same behavior as hid_hw_request, but with raw buffers instead.
 */
int hid_hw_raw_request(struct hid_device *hdev,
                       unsigned char reportnum, __u8 *buf,
                       size_t len, unsigned char rtype, int reqtype)
{
        if (len < 1 || len > HID_MAX_BUFFER_SIZE || !buf)
                return -EINVAL;

        return hdev->ll_driver->raw_request(hdev, reportnum, buf, len,
                                            rtype, reqtype);
}
EXPORT_SYMBOL_GPL(hid_hw_raw_request);

/**
 * hid_hw_output_report - send output report to device
 *
 * @hdev: hid device
 * @buf: raw data to transfer
 * @len: length of buf
 *
 * Return: count of data transferred, negative if error
 */
int hid_hw_output_report(struct hid_device *hdev, __u8 *buf, size_t len)
{
        if (len < 1 || len > HID_MAX_BUFFER_SIZE || !buf)
                return -EINVAL;

        if (hdev->ll_driver->output_report)
                return hdev->ll_driver->output_report(hdev, buf, len);

        return -ENOSYS;
}
EXPORT_SYMBOL_GPL(hid_hw_output_report);

#ifdef CONFIG_PM
int hid_driver_suspend(struct hid_device *hdev, pm_message_t state)
{
        if (hdev->driver && hdev->driver->suspend)
                return hdev->driver->suspend(hdev, state);

        return 0;
}
EXPORT_SYMBOL_GPL(hid_driver_suspend);

int hid_driver_reset_resume(struct hid_device *hdev)
{
        if (hdev->driver && hdev->driver->reset_resume)
                return hdev->driver->reset_resume(hdev);

        return 0;
}
EXPORT_SYMBOL_GPL(hid_driver_reset_resume);

int hid_driver_resume(struct hid_device *hdev)
{
        if (hdev->driver && hdev->driver->resume)
                return hdev->driver->resume(hdev);

        return 0;
}
EXPORT_SYMBOL_GPL(hid_driver_resume);
#endif /* CONFIG_PM */

struct hid_dynid {
        struct list_head list;
        struct hid_device_id id;
};

/**
 * new_id_store - add a new HID device ID to this driver and re-probe devices
 * @drv: target device driver
 * @buf: buffer for scanning device ID data
 * @count: input size
 *
 * Adds a new dynamic hid device ID to this driver,
 * and causes the driver to probe for all devices again.
 */
static ssize_t new_id_store(struct device_driver *drv, const char *buf,
                size_t count)
{
        struct hid_driver *hdrv = to_hid_driver(drv);
        struct hid_dynid *dynid;
        __u32 bus, vendor, product;
        unsigned long driver_data = 0;
        int ret;

        ret = sscanf(buf, "%x %x %x %lx",
                        &bus, &vendor, &product, &driver_data);
        if (ret < 3)
                return -EINVAL;

        dynid = kzalloc(sizeof(*dynid), GFP_KERNEL);
        if (!dynid)
                return -ENOMEM;

        dynid->id.bus = bus;
        dynid->id.group = HID_GROUP_ANY;
        dynid->id.vendor = vendor;
        dynid->id.product = product;
        dynid->id.driver_data = driver_data;

        spin_lock(&hdrv->dyn_lock);
        list_add_tail(&dynid->list, &hdrv->dyn_list);
        spin_unlock(&hdrv->dyn_lock);

        ret = driver_attach(&hdrv->driver);

        return ret ? : count;
}
static DRIVER_ATTR_WO(new_id);

static struct attribute *hid_drv_attrs[] = {
        &driver_attr_new_id.attr,
        NULL,
};
ATTRIBUTE_GROUPS(hid_drv);

static void hid_free_dynids(struct hid_driver *hdrv)
{
        struct hid_dynid *dynid, *n;

        spin_lock(&hdrv->dyn_lock);
        list_for_each_entry_safe(dynid, n, &hdrv->dyn_list, list) {
                list_del(&dynid->list);
                kfree(dynid);
        }
        spin_unlock(&hdrv->dyn_lock);
}

const struct hid_device_id *hid_match_device(struct hid_device *hdev,
                                             struct hid_driver *hdrv)
{
        struct hid_dynid *dynid;

        spin_lock(&hdrv->dyn_lock);
        list_for_each_entry(dynid, &hdrv->dyn_list, list) {
                if (hid_match_one_id(hdev, &dynid->id)) {
                        spin_unlock(&hdrv->dyn_lock);
                        return &dynid->id;
                }
        }
        spin_unlock(&hdrv->dyn_lock);

        return hid_match_id(hdev, hdrv->id_table);
}
EXPORT_SYMBOL_GPL(hid_match_device);

static int hid_bus_match(struct device *dev, struct device_driver *drv)
{
        struct hid_driver *hdrv = to_hid_driver(drv);
        struct hid_device *hdev = to_hid_device(dev);

        return hid_match_device(hdev, hdrv) != NULL;
}

/**
 * hid_compare_device_paths - check if both devices share the same path
 * @hdev_a: hid device
 * @hdev_b: hid device
 * @separator: char to use as separator
 *
 * Check if two devices share the same path up to the last occurrence of
 * the separator char. Both paths must exist (i.e., zero-length paths
 * don't match).
 */
bool hid_compare_device_paths(struct hid_device *hdev_a,
                              struct hid_device *hdev_b, char separator)
{
        int n1 = strrchr(hdev_a->phys, separator) - hdev_a->phys;
        int n2 = strrchr(hdev_b->phys, separator) - hdev_b->phys;

        if (n1 != n2 || n1 <= 0 || n2 <= 0)
                return false;

        return !strncmp(hdev_a->phys, hdev_b->phys, n1);
}
EXPORT_SYMBOL_GPL(hid_compare_device_paths);

static int hid_device_probe(struct device *dev)
{
        struct hid_driver *hdrv = to_hid_driver(dev->driver);
        struct hid_device *hdev = to_hid_device(dev);
        const struct hid_device_id *id;
        int ret = 0;

        if (down_interruptible(&hdev->driver_input_lock)) {
                ret = -EINTR;
                goto end;
        }
        hdev->io_started = false;

        clear_bit(ffs(HID_STAT_REPROBED), &hdev->status);

        if (!hdev->driver) {
                id = hid_match_device(hdev, hdrv);
                if (id == NULL) {
                        ret = -ENODEV;
                        goto unlock;
                }

                if (hdrv->match) {
                        if (!hdrv->match(hdev, hid_ignore_special_drivers)) {
                                ret = -ENODEV;
                                goto unlock;
                        }
                } else {
                        /*
                         * hid-generic implements .match(), so if
                         * hid_ignore_special_drivers is set, we can safely
                         * return.
                         */
                        if (hid_ignore_special_drivers) {
                                ret = -ENODEV;
                                goto unlock;
                        }
                }

                /* reset the quirks that has been previously set */
                hdev->quirks = hid_lookup_quirk(hdev);
                hdev->driver = hdrv;
                if (hdrv->probe) {
                        ret = hdrv->probe(hdev, id);
                } else { /* default probe */
                        ret = hid_open_report(hdev);
                        if (!ret)
                                ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
                }
                if (ret) {
                        hid_close_report(hdev);
                        hdev->driver = NULL;
                }
        }
unlock:
        if (!hdev->io_started)
                up(&hdev->driver_input_lock);
end:
        return ret;
}

static void hid_device_remove(struct device *dev)
{
        struct hid_device *hdev = to_hid_device(dev);
        struct hid_driver *hdrv;

        down(&hdev->driver_input_lock);
        hdev->io_started = false;

        hdrv = hdev->driver;
        if (hdrv) {
                if (hdrv->remove)
                        hdrv->remove(hdev);
                else /* default remove */
                        hid_hw_stop(hdev);
                hid_close_report(hdev);
                hdev->driver = NULL;
        }

        if (!hdev->io_started)
                up(&hdev->driver_input_lock);
}

static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
                             char *buf)
{
        struct hid_device *hdev = container_of(dev, struct hid_device, dev);

        return scnprintf(buf, PAGE_SIZE, "hid:b%04Xg%04Xv%08Xp%08X\n",
                         hdev->bus, hdev->group, hdev->vendor, hdev->product);
}
static DEVICE_ATTR_RO(modalias);

static struct attribute *hid_dev_attrs[] = {
        &dev_attr_modalias.attr,
        NULL,
};
static struct bin_attribute *hid_dev_bin_attrs[] = {
        &dev_bin_attr_report_desc,
        NULL
};
static const struct attribute_group hid_dev_group = {
        .attrs = hid_dev_attrs,
        .bin_attrs = hid_dev_bin_attrs,
};
__ATTRIBUTE_GROUPS(hid_dev);

static int hid_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        struct hid_device *hdev = to_hid_device(dev);

        if (add_uevent_var(env, "HID_ID=%04X:%08X:%08X",
                        hdev->bus, hdev->vendor, hdev->product))
                return -ENOMEM;

        if (add_uevent_var(env, "HID_NAME=%s", hdev->name))
                return -ENOMEM;

        if (add_uevent_var(env, "HID_PHYS=%s", hdev->phys))
                return -ENOMEM;

        if (add_uevent_var(env, "HID_UNIQ=%s", hdev->uniq))
                return -ENOMEM;

        if (add_uevent_var(env, "MODALIAS=hid:b%04Xg%04Xv%08Xp%08X",
                           hdev->bus, hdev->group, hdev->vendor, hdev->product))
                return -ENOMEM;

        return 0;
}

struct bus_type hid_bus_type = {
        .name           = "hid",
        .dev_groups     = hid_dev_groups,
        .drv_groups     = hid_drv_groups,
        .match          = hid_bus_match,
        .probe          = hid_device_probe,
        .remove         = hid_device_remove,
        .uevent         = hid_uevent,
};
EXPORT_SYMBOL(hid_bus_type);

int hid_add_device(struct hid_device *hdev)
{
        static atomic_t id = ATOMIC_INIT(0);
        int ret;

        if (WARN_ON(hdev->status & HID_STAT_ADDED))
                return -EBUSY;

        hdev->quirks = hid_lookup_quirk(hdev);

        /* we need to kill them here, otherwise they will stay allocated to
         * wait for coming driver */
        if (hid_ignore(hdev))
                return -ENODEV;

        /*
         * Check for the mandatory transport channel.
         */
         if (!hdev->ll_driver->raw_request) {
                hid_err(hdev, "transport driver missing .raw_request()\n");
                return -EINVAL;
         }

        /*
         * Read the device report descriptor once and use as template
         * for the driver-specific modifications.
         */
        ret = hdev->ll_driver->parse(hdev);
        if (ret)
                return ret;
        if (!hdev->dev_rdesc)
                return -ENODEV;

        /*
         * Scan generic devices for group information
         */
        if (hid_ignore_special_drivers) {
                hdev->group = HID_GROUP_GENERIC;
        } else if (!hdev->group &&
                   !(hdev->quirks & HID_QUIRK_HAVE_SPECIAL_DRIVER)) {
                ret = hid_scan_report(hdev);
                if (ret)
                        hid_warn(hdev, "bad device descriptor (%d)\n", ret);
        }

        /* XXX hack, any other cleaner solution after the driver core
         * is converted to allow more than 20 bytes as the device name? */
        dev_set_name(&hdev->dev, "%04X:%04X:%04X.%04X", hdev->bus,
                     hdev->vendor, hdev->product, atomic_inc_return(&id));

        hid_debug_register(hdev, dev_name(&hdev->dev));
        ret = device_add(&hdev->dev);
        if (!ret)
                hdev->status |= HID_STAT_ADDED;
        else
                hid_debug_unregister(hdev);

        return ret;
}
EXPORT_SYMBOL_GPL(hid_add_device);

/**
 * hid_allocate_device - allocate new hid device descriptor
 *
 * Allocate and initialize hid device, so that hid_destroy_device might be
 * used to free it.
 *
 * New hid_device pointer is returned on success, otherwise ERR_PTR encoded
 * error value.
 */
struct hid_device *hid_allocate_device(void)
{
        struct hid_device *hdev;
        int ret = -ENOMEM;

        hdev = kzalloc(sizeof(*hdev), GFP_KERNEL);
        if (hdev == NULL)
                return ERR_PTR(ret);

        device_initialize(&hdev->dev);
        hdev->dev.release = hid_device_release;
        hdev->dev.bus = &hid_bus_type;
        device_enable_async_suspend(&hdev->dev);

        hid_close_report(hdev);

        init_waitqueue_head(&hdev->debug_wait);
        INIT_LIST_HEAD(&hdev->debug_list);
        spin_lock_init(&hdev->debug_list_lock);
        sema_init(&hdev->driver_input_lock, 1);
        mutex_init(&hdev->ll_open_lock);

        return hdev;
}
EXPORT_SYMBOL_GPL(hid_allocate_device);

static void hid_remove_device(struct hid_device *hdev)
{
        if (hdev->status & HID_STAT_ADDED) {
                device_del(&hdev->dev);
                hid_debug_unregister(hdev);
                hdev->status &= ~HID_STAT_ADDED;
        }
        kfree(hdev->dev_rdesc);
        hdev->dev_rdesc = NULL;
        hdev->dev_rsize = 0;
}

/**
 * hid_destroy_device - free previously allocated device
 *
 * @hdev: hid device
 *
 * If you allocate hid_device through hid_allocate_device, you should ever
 * free by this function.
 */
void hid_destroy_device(struct hid_device *hdev)
{
        hid_remove_device(hdev);
        put_device(&hdev->dev);
}
EXPORT_SYMBOL_GPL(hid_destroy_device);


static int __hid_bus_reprobe_drivers(struct device *dev, void *data)
{
        struct hid_driver *hdrv = data;
        struct hid_device *hdev = to_hid_device(dev);

        if (hdev->driver == hdrv &&
            !hdrv->match(hdev, hid_ignore_special_drivers) &&
            !test_and_set_bit(ffs(HID_STAT_REPROBED), &hdev->status))
                return device_reprobe(dev);

        return 0;
}

static int __hid_bus_driver_added(struct device_driver *drv, void *data)
{
        struct hid_driver *hdrv = to_hid_driver(drv);

        if (hdrv->match) {
                bus_for_each_dev(&hid_bus_type, NULL, hdrv,
                                 __hid_bus_reprobe_drivers);
        }

        return 0;
}

static int __bus_removed_driver(struct device_driver *drv, void *data)
{
        return bus_rescan_devices(&hid_bus_type);
}

int __hid_register_driver(struct hid_driver *hdrv, struct module *owner,
                const char *mod_name)
{
        int ret;

        hdrv->driver.name = hdrv->name;
        hdrv->driver.bus = &hid_bus_type;
        hdrv->driver.owner = owner;
        hdrv->driver.mod_name = mod_name;

        INIT_LIST_HEAD(&hdrv->dyn_list);
        spin_lock_init(&hdrv->dyn_lock);

        ret = driver_register(&hdrv->driver);

        if (ret == 0)
                bus_for_each_drv(&hid_bus_type, NULL, NULL,
                                 __hid_bus_driver_added);

        return ret;
}
EXPORT_SYMBOL_GPL(__hid_register_driver);

void hid_unregister_driver(struct hid_driver *hdrv)
{
        driver_unregister(&hdrv->driver);
        hid_free_dynids(hdrv);

        bus_for_each_drv(&hid_bus_type, NULL, hdrv, __bus_removed_driver);
}
EXPORT_SYMBOL_GPL(hid_unregister_driver);

int hid_check_keys_pressed(struct hid_device *hid)
{
        struct hid_input *hidinput;
        int i;

        if (!(hid->claimed & HID_CLAIMED_INPUT))
                return 0;

        list_for_each_entry(hidinput, &hid->inputs, list) {
                for (i = 0; i < BITS_TO_LONGS(KEY_MAX); i++)
                        if (hidinput->input->key[i])
                                return 1;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(hid_check_keys_pressed);

static int __init hid_init(void)
{
        int ret;

        if (hid_debug)
                pr_warn("hid_debug is now used solely for parser and driver debugging.\n"
                        "debugfs is now used for inspecting the device (report descriptor, reports)\n");

        ret = bus_register(&hid_bus_type);
        if (ret) {
                pr_err("can't register hid bus\n");
                goto err;
        }

        ret = hidraw_init();
        if (ret)
                goto err_bus;

        hid_debug_init();

        return 0;
err_bus:
        bus_unregister(&hid_bus_type);
err:
        return ret;
}

static void __exit hid_exit(void)
{
        hid_debug_exit();
        hidraw_exit();
        bus_unregister(&hid_bus_type);
        hid_quirks_exit(HID_BUS_ANY);
}

module_init(hid_init);
module_exit(hid_exit);

MODULE_AUTHOR("Andreas Gal");
MODULE_AUTHOR("Vojtech Pavlik");
MODULE_AUTHOR("Jiri Kosina");
MODULE_LICENSE("GPL");