linux-hardened/include/linux/uhid.h
David Herrmann fcfcf0deb8 HID: uhid: implement feature requests
HID standard allows sending a feature request to the device which is
answered by an HID report. uhid implements this by sending a UHID_FEATURE
event to user-space which then must answer with UHID_FEATURE_ANSWER. If it
doesn't do this in a timely manner, the request is discarded silently.

We serialize the feature requests, that is, there is always only a single
active feature-request sent to user-space, other requests have to wait.
HIDP and USB-HID do it the same way.

Because we discard feature-requests silently, we must make sure to match
a response to the corresponding request. We use sequence-IDs for this so
user-space must copy the ID from the request into the answer.
Feature-answers are ignored if they do not contain the same ID as the
currently pending feature request.

Internally, we must make sure that feature-requests are synchronized with
UHID_DESTROY and close() events. We must not dead-lock when closing the
HID device, either, so we have to use separate locks.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18 13:42:03 +02:00

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C

#ifndef __UHID_H_
#define __UHID_H_
/*
* User-space I/O driver support for HID subsystem
* Copyright (c) 2012 David Herrmann
*/
/*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*/
/*
* Public header for user-space communication. We try to keep every structure
* aligned but to be safe we also use __attribute__((__packed__)). Therefore,
* the communication should be ABI compatible even between architectures.
*/
#include <linux/input.h>
#include <linux/types.h>
enum uhid_event_type {
UHID_CREATE,
UHID_DESTROY,
UHID_START,
UHID_STOP,
UHID_OPEN,
UHID_CLOSE,
UHID_OUTPUT,
UHID_OUTPUT_EV,
UHID_INPUT,
UHID_FEATURE,
UHID_FEATURE_ANSWER,
};
struct uhid_create_req {
__u8 name[128];
__u8 phys[64];
__u8 uniq[64];
__u8 __user *rd_data;
__u16 rd_size;
__u16 bus;
__u32 vendor;
__u32 product;
__u32 version;
__u32 country;
} __attribute__((__packed__));
#define UHID_DATA_MAX 4096
enum uhid_report_type {
UHID_FEATURE_REPORT,
UHID_OUTPUT_REPORT,
UHID_INPUT_REPORT,
};
struct uhid_input_req {
__u8 data[UHID_DATA_MAX];
__u16 size;
} __attribute__((__packed__));
struct uhid_output_req {
__u8 data[UHID_DATA_MAX];
__u16 size;
__u8 rtype;
} __attribute__((__packed__));
struct uhid_output_ev_req {
__u16 type;
__u16 code;
__s32 value;
} __attribute__((__packed__));
struct uhid_feature_req {
__u32 id;
__u8 rnum;
__u8 rtype;
} __attribute__((__packed__));
struct uhid_feature_answer_req {
__u32 id;
__u16 err;
__u16 size;
__u8 data[UHID_DATA_MAX];
};
struct uhid_event {
__u32 type;
union {
struct uhid_create_req create;
struct uhid_input_req input;
struct uhid_output_req output;
struct uhid_output_ev_req output_ev;
struct uhid_feature_req feature;
struct uhid_feature_answer_req feature_answer;
} u;
} __attribute__((__packed__));
#endif /* __UHID_H_ */