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freebsd-dev/sys/dev/usb/usb_hid.c
Hans Petter Selasky eff8154913 USB HID descriptors may push/pop the current state to allow 
description of items residing in a so-called union. FreeBSD currently
only supports 4 such pop levels.

If the push level is not restored within the processing of the same
HID item, an invalid memory location may be used for subsequent HID
item processing.

Verify that the push level is always valid when processing HID items.

Reported by:	Andy Nguyen (Google)
MFC after:	3 days
Sponsored by:	Mellanox Technologies
2020-06-05 07:57:16 +00:00

1002 lines
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/* $FreeBSD$ */
/* $NetBSD: hid.c,v 1.17 2001/11/13 06:24:53 lukem Exp $ */
/*-
* SPDX-License-Identifier: BSD-2-Clause-NetBSD
*
* Copyright (c) 1998 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Lennart Augustsson (lennart@augustsson.net) at
* Carlstedt Research & Technology.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef USB_GLOBAL_INCLUDE_FILE
#include USB_GLOBAL_INCLUDE_FILE
#else
#include <sys/stdint.h>
#include <sys/stddef.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/priv.h>
#include <dev/usb/usb.h>
#include <dev/usb/usbdi.h>
#include <dev/usb/usbdi_util.h>
#include <dev/usb/usbhid.h>
#define USB_DEBUG_VAR usb_debug
#include <dev/usb/usb_core.h>
#include <dev/usb/usb_debug.h>
#include <dev/usb/usb_process.h>
#include <dev/usb/usb_device.h>
#include <dev/usb/usb_request.h>
#endif /* USB_GLOBAL_INCLUDE_FILE */
static void hid_clear_local(struct hid_item *);
static uint8_t hid_get_byte(struct hid_data *s, const uint16_t wSize);
#define MAXUSAGE 64
#define MAXPUSH 4
#define MAXID 16
#define MAXLOCCNT 2048
struct hid_pos_data {
int32_t rid;
uint32_t pos;
};
struct hid_data {
const uint8_t *start;
const uint8_t *end;
const uint8_t *p;
struct hid_item cur[MAXPUSH];
struct hid_pos_data last_pos[MAXID];
int32_t usages_min[MAXUSAGE];
int32_t usages_max[MAXUSAGE];
int32_t usage_last; /* last seen usage */
uint32_t loc_size; /* last seen size */
uint32_t loc_count; /* last seen count */
uint32_t ncount; /* end usage item count */
uint32_t icount; /* current usage item count */
uint8_t kindset; /* we have 5 kinds so 8 bits are enough */
uint8_t pushlevel; /* current pushlevel */
uint8_t nusage; /* end "usages_min/max" index */
uint8_t iusage; /* current "usages_min/max" index */
uint8_t ousage; /* current "usages_min/max" offset */
uint8_t susage; /* usage set flags */
};
/*------------------------------------------------------------------------*
* hid_clear_local
*------------------------------------------------------------------------*/
static void
hid_clear_local(struct hid_item *c)
{
c->loc.count = 0;
c->loc.size = 0;
c->usage = 0;
c->usage_minimum = 0;
c->usage_maximum = 0;
c->designator_index = 0;
c->designator_minimum = 0;
c->designator_maximum = 0;
c->string_index = 0;
c->string_minimum = 0;
c->string_maximum = 0;
c->set_delimiter = 0;
}
static void
hid_switch_rid(struct hid_data *s, struct hid_item *c, int32_t next_rID)
{
uint8_t i;
/* check for same report ID - optimise */
if (c->report_ID == next_rID)
return;
/* save current position for current rID */
if (c->report_ID == 0) {
i = 0;
} else {
for (i = 1; i != MAXID; i++) {
if (s->last_pos[i].rid == c->report_ID)
break;
if (s->last_pos[i].rid == 0)
break;
}
}
if (i != MAXID) {
s->last_pos[i].rid = c->report_ID;
s->last_pos[i].pos = c->loc.pos;
}
/* store next report ID */
c->report_ID = next_rID;
/* lookup last position for next rID */
if (next_rID == 0) {
i = 0;
} else {
for (i = 1; i != MAXID; i++) {
if (s->last_pos[i].rid == next_rID)
break;
if (s->last_pos[i].rid == 0)
break;
}
}
if (i != MAXID) {
s->last_pos[i].rid = next_rID;
c->loc.pos = s->last_pos[i].pos;
} else {
DPRINTF("Out of RID entries, position is set to zero!\n");
c->loc.pos = 0;
}
}
/*------------------------------------------------------------------------*
* hid_start_parse
*------------------------------------------------------------------------*/
struct hid_data *
hid_start_parse(const void *d, usb_size_t len, int kindset)
{
struct hid_data *s;
if ((kindset-1) & kindset) {
DPRINTFN(0, "Only one bit can be "
"set in the kindset\n");
return (NULL);
}
s = malloc(sizeof *s, M_TEMP, M_WAITOK | M_ZERO);
s->start = s->p = d;
s->end = ((const uint8_t *)d) + len;
s->kindset = kindset;
return (s);
}
/*------------------------------------------------------------------------*
* hid_end_parse
*------------------------------------------------------------------------*/
void
hid_end_parse(struct hid_data *s)
{
if (s == NULL)
return;
free(s, M_TEMP);
}
/*------------------------------------------------------------------------*
* get byte from HID descriptor
*------------------------------------------------------------------------*/
static uint8_t
hid_get_byte(struct hid_data *s, const uint16_t wSize)
{
const uint8_t *ptr;
uint8_t retval;
ptr = s->p;
/* check if end is reached */
if (ptr == s->end)
return (0);
/* read out a byte */
retval = *ptr;
/* check if data pointer can be advanced by "wSize" bytes */
if ((s->end - ptr) < wSize)
ptr = s->end;
else
ptr += wSize;
/* update pointer */
s->p = ptr;
return (retval);
}
/*------------------------------------------------------------------------*
* hid_get_item
*------------------------------------------------------------------------*/
int
hid_get_item(struct hid_data *s, struct hid_item *h)
{
struct hid_item *c;
unsigned int bTag, bType, bSize;
uint32_t oldpos;
int32_t mask;
int32_t dval;
if (s == NULL)
return (0);
c = &s->cur[s->pushlevel];
top:
/* check if there is an array of items */
if (s->icount < s->ncount) {
/* get current usage */
if (s->iusage < s->nusage) {
dval = s->usages_min[s->iusage] + s->ousage;
c->usage = dval;
s->usage_last = dval;
if (dval == s->usages_max[s->iusage]) {
s->iusage ++;
s->ousage = 0;
} else {
s->ousage ++;
}
} else {
DPRINTFN(1, "Using last usage\n");
dval = s->usage_last;
}
s->icount ++;
/*
* Only copy HID item, increment position and return
* if correct kindset!
*/
if (s->kindset & (1 << c->kind)) {
*h = *c;
DPRINTFN(1, "%u,%u,%u\n", h->loc.pos,
h->loc.size, h->loc.count);
c->loc.pos += c->loc.size * c->loc.count;
return (1);
}
}
/* reset state variables */
s->icount = 0;
s->ncount = 0;
s->iusage = 0;
s->nusage = 0;
s->susage = 0;
s->ousage = 0;
hid_clear_local(c);
/* get next item */
while (s->p != s->end) {
bSize = hid_get_byte(s, 1);
if (bSize == 0xfe) {
/* long item */
bSize = hid_get_byte(s, 1);
bSize |= hid_get_byte(s, 1) << 8;
bTag = hid_get_byte(s, 1);
bType = 0xff; /* XXX what should it be */
} else {
/* short item */
bTag = bSize >> 4;
bType = (bSize >> 2) & 3;
bSize &= 3;
if (bSize == 3)
bSize = 4;
}
switch (bSize) {
case 0:
dval = 0;
mask = 0;
break;
case 1:
dval = (int8_t)hid_get_byte(s, 1);
mask = 0xFF;
break;
case 2:
dval = hid_get_byte(s, 1);
dval |= hid_get_byte(s, 1) << 8;
dval = (int16_t)dval;
mask = 0xFFFF;
break;
case 4:
dval = hid_get_byte(s, 1);
dval |= hid_get_byte(s, 1) << 8;
dval |= hid_get_byte(s, 1) << 16;
dval |= hid_get_byte(s, 1) << 24;
mask = 0xFFFFFFFF;
break;
default:
dval = hid_get_byte(s, bSize);
DPRINTFN(0, "bad length %u (data=0x%02x)\n",
bSize, dval);
continue;
}
switch (bType) {
case 0: /* Main */
switch (bTag) {
case 8: /* Input */
c->kind = hid_input;
ret:
c->flags = dval;
c->loc.count = s->loc_count;
c->loc.size = s->loc_size;
if (c->flags & HIO_VARIABLE) {
/* range check usage count */
if (c->loc.count > MAXLOCCNT) {
DPRINTFN(0, "Number of "
"items(%u) truncated to %u\n",
(unsigned)(c->loc.count),
MAXLOCCNT);
s->ncount = MAXLOCCNT;
} else
s->ncount = c->loc.count;
/*
* The "top" loop will return
* one and one item:
*/
c->loc.count = 1;
} else {
s->ncount = 1;
}
goto top;
case 9: /* Output */
c->kind = hid_output;
goto ret;
case 10: /* Collection */
c->kind = hid_collection;
c->collection = dval;
c->collevel++;
c->usage = s->usage_last;
*h = *c;
return (1);
case 11: /* Feature */
c->kind = hid_feature;
goto ret;
case 12: /* End collection */
c->kind = hid_endcollection;
if (c->collevel == 0) {
DPRINTFN(0, "invalid end collection\n");
return (0);
}
c->collevel--;
*h = *c;
return (1);
default:
DPRINTFN(0, "Main bTag=%d\n", bTag);
break;
}
break;
case 1: /* Global */
switch (bTag) {
case 0:
c->_usage_page = dval << 16;
break;
case 1:
c->logical_minimum = dval;
break;
case 2:
c->logical_maximum = dval;
break;
case 3:
c->physical_minimum = dval;
break;
case 4:
c->physical_maximum = dval;
break;
case 5:
c->unit_exponent = dval;
break;
case 6:
c->unit = dval;
break;
case 7:
/* mask because value is unsigned */
s->loc_size = dval & mask;
break;
case 8:
hid_switch_rid(s, c, dval & mask);
break;
case 9:
/* mask because value is unsigned */
s->loc_count = dval & mask;
break;
case 10: /* Push */
/* stop parsing, if invalid push level */
if ((s->pushlevel + 1) >= MAXPUSH) {
DPRINTFN(0, "Cannot push item @ %d\n", s->pushlevel);
return (0);
}
s->pushlevel ++;
s->cur[s->pushlevel] = *c;
/* store size and count */
c->loc.size = s->loc_size;
c->loc.count = s->loc_count;
/* update current item pointer */
c = &s->cur[s->pushlevel];
break;
case 11: /* Pop */
/* stop parsing, if invalid push level */
if (s->pushlevel == 0) {
DPRINTFN(0, "Cannot pop item @ 0\n");
return (0);
}
s->pushlevel --;
/* preserve position */
oldpos = c->loc.pos;
c = &s->cur[s->pushlevel];
/* restore size and count */
s->loc_size = c->loc.size;
s->loc_count = c->loc.count;
/* set default item location */
c->loc.pos = oldpos;
c->loc.size = 0;
c->loc.count = 0;
break;
default:
DPRINTFN(0, "Global bTag=%d\n", bTag);
break;
}
break;
case 2: /* Local */
switch (bTag) {
case 0:
if (bSize != 4)
dval = (dval & mask) | c->_usage_page;
/* set last usage, in case of a collection */
s->usage_last = dval;
if (s->nusage < MAXUSAGE) {
s->usages_min[s->nusage] = dval;
s->usages_max[s->nusage] = dval;
s->nusage ++;
} else {
DPRINTFN(0, "max usage reached\n");
}
/* clear any pending usage sets */
s->susage = 0;
break;
case 1:
s->susage |= 1;
if (bSize != 4)
dval = (dval & mask) | c->_usage_page;
c->usage_minimum = dval;
goto check_set;
case 2:
s->susage |= 2;
if (bSize != 4)
dval = (dval & mask) | c->_usage_page;
c->usage_maximum = dval;
check_set:
if (s->susage != 3)
break;
/* sanity check */
if ((s->nusage < MAXUSAGE) &&
(c->usage_minimum <= c->usage_maximum)) {
/* add usage range */
s->usages_min[s->nusage] =
c->usage_minimum;
s->usages_max[s->nusage] =
c->usage_maximum;
s->nusage ++;
} else {
DPRINTFN(0, "Usage set dropped\n");
}
s->susage = 0;
break;
case 3:
c->designator_index = dval;
break;
case 4:
c->designator_minimum = dval;
break;
case 5:
c->designator_maximum = dval;
break;
case 7:
c->string_index = dval;
break;
case 8:
c->string_minimum = dval;
break;
case 9:
c->string_maximum = dval;
break;
case 10:
c->set_delimiter = dval;
break;
default:
DPRINTFN(0, "Local bTag=%d\n", bTag);
break;
}
break;
default:
DPRINTFN(0, "default bType=%d\n", bType);
break;
}
}
return (0);
}
/*------------------------------------------------------------------------*
* hid_report_size
*------------------------------------------------------------------------*/
int
hid_report_size(const void *buf, usb_size_t len, enum hid_kind k, uint8_t *id)
{
struct hid_data *d;
struct hid_item h;
uint32_t temp;
uint32_t hpos;
uint32_t lpos;
uint8_t any_id;
any_id = 0;
hpos = 0;
lpos = 0xFFFFFFFF;
for (d = hid_start_parse(buf, len, 1 << k); hid_get_item(d, &h);) {
if (h.kind == k) {
/* check for ID-byte presence */
if ((h.report_ID != 0) && !any_id) {
if (id != NULL)
*id = h.report_ID;
any_id = 1;
}
/* compute minimum */
if (lpos > h.loc.pos)
lpos = h.loc.pos;
/* compute end position */
temp = h.loc.pos + (h.loc.size * h.loc.count);
/* compute maximum */
if (hpos < temp)
hpos = temp;
}
}
hid_end_parse(d);
/* safety check - can happen in case of currupt descriptors */
if (lpos > hpos)
temp = 0;
else
temp = hpos - lpos;
/* check for ID byte */
if (any_id)
temp += 8;
else if (id != NULL)
*id = 0;
/* return length in bytes rounded up */
return ((temp + 7) / 8);
}
/*------------------------------------------------------------------------*
* hid_locate
*------------------------------------------------------------------------*/
int
hid_locate(const void *desc, usb_size_t size, int32_t u, enum hid_kind k,
uint8_t index, struct hid_location *loc, uint32_t *flags, uint8_t *id)
{
struct hid_data *d;
struct hid_item h;
for (d = hid_start_parse(desc, size, 1 << k); hid_get_item(d, &h);) {
if (h.kind == k && !(h.flags & HIO_CONST) && h.usage == u) {
if (index--)
continue;
if (loc != NULL)
*loc = h.loc;
if (flags != NULL)
*flags = h.flags;
if (id != NULL)
*id = h.report_ID;
hid_end_parse(d);
return (1);
}
}
if (loc != NULL)
loc->size = 0;
if (flags != NULL)
*flags = 0;
if (id != NULL)
*id = 0;
hid_end_parse(d);
return (0);
}
/*------------------------------------------------------------------------*
* hid_get_data
*------------------------------------------------------------------------*/
static uint32_t
hid_get_data_sub(const uint8_t *buf, usb_size_t len, struct hid_location *loc,
int is_signed)
{
uint32_t hpos = loc->pos;
uint32_t hsize = loc->size;
uint32_t data;
uint32_t rpos;
uint8_t n;
DPRINTFN(11, "hid_get_data: loc %d/%d\n", hpos, hsize);
/* Range check and limit */
if (hsize == 0)
return (0);
if (hsize > 32)
hsize = 32;
/* Get data in a safe way */
data = 0;
rpos = (hpos / 8);
n = (hsize + 7) / 8;
rpos += n;
while (n--) {
rpos--;
if (rpos < len)
data |= buf[rpos] << (8 * n);
}
/* Correctly shift down data */
data = (data >> (hpos % 8));
n = 32 - hsize;
/* Mask and sign extend in one */
if (is_signed != 0)
data = (int32_t)((int32_t)data << n) >> n;
else
data = (uint32_t)((uint32_t)data << n) >> n;
DPRINTFN(11, "hid_get_data: loc %d/%d = %lu\n",
loc->pos, loc->size, (long)data);
return (data);
}
int32_t
hid_get_data(const uint8_t *buf, usb_size_t len, struct hid_location *loc)
{
return (hid_get_data_sub(buf, len, loc, 1));
}
uint32_t
hid_get_data_unsigned(const uint8_t *buf, usb_size_t len, struct hid_location *loc)
{
return (hid_get_data_sub(buf, len, loc, 0));
}
/*------------------------------------------------------------------------*
* hid_put_data
*------------------------------------------------------------------------*/
void
hid_put_data_unsigned(uint8_t *buf, usb_size_t len,
struct hid_location *loc, unsigned int value)
{
uint32_t hpos = loc->pos;
uint32_t hsize = loc->size;
uint64_t data;
uint64_t mask;
uint32_t rpos;
uint8_t n;
DPRINTFN(11, "hid_put_data: loc %d/%d = %u\n", hpos, hsize, value);
/* Range check and limit */
if (hsize == 0)
return;
if (hsize > 32)
hsize = 32;
/* Put data in a safe way */
rpos = (hpos / 8);
n = (hsize + 7) / 8;
data = ((uint64_t)value) << (hpos % 8);
mask = ((1ULL << hsize) - 1ULL) << (hpos % 8);
rpos += n;
while (n--) {
rpos--;
if (rpos < len) {
buf[rpos] &= ~(mask >> (8 * n));
buf[rpos] |= (data >> (8 * n));
}
}
}
/*------------------------------------------------------------------------*
* hid_is_collection
*------------------------------------------------------------------------*/
int
hid_is_collection(const void *desc, usb_size_t size, int32_t usage)
{
struct hid_data *hd;
struct hid_item hi;
int err;
hd = hid_start_parse(desc, size, hid_input);
if (hd == NULL)
return (0);
while ((err = hid_get_item(hd, &hi))) {
if (hi.kind == hid_collection &&
hi.usage == usage)
break;
}
hid_end_parse(hd);
return (err);
}
/*------------------------------------------------------------------------*
* hid_get_descriptor_from_usb
*
* This function will search for a HID descriptor between two USB
* interface descriptors.
*
* Return values:
* NULL: No more HID descriptors.
* Else: Pointer to HID descriptor.
*------------------------------------------------------------------------*/
struct usb_hid_descriptor *
hid_get_descriptor_from_usb(struct usb_config_descriptor *cd,
struct usb_interface_descriptor *id)
{
struct usb_descriptor *desc = (void *)id;
if (desc == NULL) {
return (NULL);
}
while ((desc = usb_desc_foreach(cd, desc))) {
if ((desc->bDescriptorType == UDESC_HID) &&
(desc->bLength >= USB_HID_DESCRIPTOR_SIZE(0))) {
return (void *)desc;
}
if (desc->bDescriptorType == UDESC_INTERFACE) {
break;
}
}
return (NULL);
}
/*------------------------------------------------------------------------*
* usbd_req_get_hid_desc
*
* This function will read out an USB report descriptor from the USB
* device.
*
* Return values:
* NULL: Failure.
* Else: Success. The pointer should eventually be passed to free().
*------------------------------------------------------------------------*/
usb_error_t
usbd_req_get_hid_desc(struct usb_device *udev, struct mtx *mtx,
void **descp, uint16_t *sizep,
struct malloc_type *mem, uint8_t iface_index)
{
struct usb_interface *iface = usbd_get_iface(udev, iface_index);
struct usb_hid_descriptor *hid;
usb_error_t err;
if ((iface == NULL) || (iface->idesc == NULL)) {
return (USB_ERR_INVAL);
}
hid = hid_get_descriptor_from_usb
(usbd_get_config_descriptor(udev), iface->idesc);
if (hid == NULL) {
return (USB_ERR_IOERROR);
}
*sizep = UGETW(hid->descrs[0].wDescriptorLength);
if (*sizep == 0) {
return (USB_ERR_IOERROR);
}
if (mtx)
mtx_unlock(mtx);
*descp = malloc(*sizep, mem, M_ZERO | M_WAITOK);
if (mtx)
mtx_lock(mtx);
if (*descp == NULL) {
return (USB_ERR_NOMEM);
}
err = usbd_req_get_report_descriptor
(udev, mtx, *descp, *sizep, iface_index);
if (err) {
free(*descp, mem);
*descp = NULL;
return (err);
}
return (USB_ERR_NORMAL_COMPLETION);
}
/*------------------------------------------------------------------------*
* calculate HID item resolution. unit/mm for distances, unit/rad for angles
*------------------------------------------------------------------------*/
int32_t
hid_item_resolution(struct hid_item *hi)
{
/*
* hid unit scaling table according to HID Usage Table Review
* Request 39 Tbl 17 http://www.usb.org/developers/hidpage/HUTRR39b.pdf
*/
static const int64_t scale[0x10][2] = {
[0x00] = { 1, 1 },
[0x01] = { 1, 10 },
[0x02] = { 1, 100 },
[0x03] = { 1, 1000 },
[0x04] = { 1, 10000 },
[0x05] = { 1, 100000 },
[0x06] = { 1, 1000000 },
[0x07] = { 1, 10000000 },
[0x08] = { 100000000, 1 },
[0x09] = { 10000000, 1 },
[0x0A] = { 1000000, 1 },
[0x0B] = { 100000, 1 },
[0x0C] = { 10000, 1 },
[0x0D] = { 1000, 1 },
[0x0E] = { 100, 1 },
[0x0F] = { 10, 1 },
};
int64_t logical_size;
int64_t physical_size;
int64_t multiplier;
int64_t divisor;
int64_t resolution;
switch (hi->unit) {
case HUM_CENTIMETER:
multiplier = 1;
divisor = 10;
break;
case HUM_INCH:
multiplier = 10;
divisor = 254;
break;
case HUM_RADIAN:
multiplier = 1;
divisor = 1;
break;
case HUM_DEGREE:
multiplier = 573;
divisor = 10;
break;
default:
return (0);
}
if ((hi->logical_maximum <= hi->logical_minimum) ||
(hi->physical_maximum <= hi->physical_minimum) ||
(hi->unit_exponent < 0) || (hi->unit_exponent >= nitems(scale)))
return (0);
logical_size = (int64_t)hi->logical_maximum -
(int64_t)hi->logical_minimum;
physical_size = (int64_t)hi->physical_maximum -
(int64_t)hi->physical_minimum;
/* Round to ceiling */
resolution = logical_size * multiplier * scale[hi->unit_exponent][0] /
(physical_size * divisor * scale[hi->unit_exponent][1]);
if (resolution > INT32_MAX)
return (0);
return (resolution);
}
/*------------------------------------------------------------------------*
* hid_is_mouse
*
* This function will decide if a USB descriptor belongs to a USB mouse.
*
* Return values:
* Zero: Not a USB mouse.
* Else: Is a USB mouse.
*------------------------------------------------------------------------*/
int
hid_is_mouse(const void *d_ptr, uint16_t d_len)
{
struct hid_data *hd;
struct hid_item hi;
int mdepth;
int found;
hd = hid_start_parse(d_ptr, d_len, 1 << hid_input);
if (hd == NULL)
return (0);
mdepth = 0;
found = 0;
while (hid_get_item(hd, &hi)) {
switch (hi.kind) {
case hid_collection:
if (mdepth != 0)
mdepth++;
else if (hi.collection == 1 &&
hi.usage ==
HID_USAGE2(HUP_GENERIC_DESKTOP, HUG_MOUSE))
mdepth++;
break;
case hid_endcollection:
if (mdepth != 0)
mdepth--;
break;
case hid_input:
if (mdepth == 0)
break;
if (hi.usage ==
HID_USAGE2(HUP_GENERIC_DESKTOP, HUG_X) &&
(hi.flags & (HIO_CONST|HIO_RELATIVE)) == HIO_RELATIVE)
found++;
if (hi.usage ==
HID_USAGE2(HUP_GENERIC_DESKTOP, HUG_Y) &&
(hi.flags & (HIO_CONST|HIO_RELATIVE)) == HIO_RELATIVE)
found++;
break;
default:
break;
}
}
hid_end_parse(hd);
return (found);
}
/*------------------------------------------------------------------------*
* hid_is_keyboard
*
* This function will decide if a USB descriptor belongs to a USB keyboard.
*
* Return values:
* Zero: Not a USB keyboard.
* Else: Is a USB keyboard.
*------------------------------------------------------------------------*/
int
hid_is_keyboard(const void *d_ptr, uint16_t d_len)
{
if (hid_is_collection(d_ptr, d_len,
HID_USAGE2(HUP_GENERIC_DESKTOP, HUG_KEYBOARD)))
return (1);
return (0);
}
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