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Documentation: HID: uhid editing & corrections

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Do basic editing & correction to hid-alps.rst:
- correct a file name (.txt -> .rst)
- use less hyphenation when not needed
- fix grammar & punctuation
- fix article adjectives
- fix typos/spellos
- use HID instead of hid consistently

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: linux-input@vger.kernel.org
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Jonathan Cameron <jic23@kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Randy Dunlap 2020-12-28 12:53:27 -08:00 committed by Jiri Kosina
parent a14e9d7285
commit 356006a6cf
1 changed files with 17 additions and 17 deletions
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34
Documentation/hid/uhid.rst
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@ -3,7 +3,7 @@ UHID - User-space I/O driver support for HID subsystem
======================================================
UHID allows user-space to implement HID transport drivers. Please see
hid-transport.txt for an introduction into HID transport drivers. This document
hid-transport.rst for an introduction into HID transport drivers. This document
relies heavily on the definitions declared there.
With UHID, a user-space transport driver can create kernel hid-devices for each
@ -15,7 +15,7 @@ There is an example user-space application in ./samples/uhid/uhid-example.c
The UHID API
------------
UHID is accessed through a character misc-device. The minor-number is allocated
UHID is accessed through a character misc-device. The minor number is allocated
dynamically so you need to rely on udev (or similar) to create the device node.
This is /dev/uhid by default.
@ -45,23 +45,23 @@ The "type" field defines the payload. For each type, there is a
payload-structure available in the union "u" (except for empty payloads). This
payload contains management and/or device data.
The first thing you should do is sending an UHID_CREATE2 event. This will
register the device. UHID will respond with an UHID_START event. You can now
The first thing you should do is send a UHID_CREATE2 event. This will
register the device. UHID will respond with a UHID_START event. You can now
start sending data to and reading data from UHID. However, unless UHID sends the
UHID_OPEN event, the internally attached HID Device Driver has no user attached.
That is, you might put your device asleep unless you receive the UHID_OPEN
event. If you receive the UHID_OPEN event, you should start I/O. If the last
user closes the HID device, you will receive an UHID_CLOSE event. This may be
followed by an UHID_OPEN event again and so on. There is no need to perform
user closes the HID device, you will receive a UHID_CLOSE event. This may be
followed by a UHID_OPEN event again and so on. There is no need to perform
reference-counting in user-space. That is, you will never receive multiple
UHID_OPEN events without an UHID_CLOSE event. The HID subsystem performs
UHID_OPEN events without a UHID_CLOSE event. The HID subsystem performs
ref-counting for you.
You may decide to ignore UHID_OPEN/UHID_CLOSE, though. I/O is allowed even
though the device may have no users.
If you want to send data on the interrupt channel to the HID subsystem, you send
an HID_INPUT2 event with your raw data payload. If the kernel wants to send data
on the interrupt channel to the device, you will read an UHID_OUTPUT event.
a HID_INPUT2 event with your raw data payload. If the kernel wants to send data
on the interrupt channel to the device, you will read a UHID_OUTPUT event.
Data requests on the control channel are currently limited to GET_REPORT and
SET_REPORT (no other data reports on the control channel are defined so far).
Those requests are always synchronous. That means, the kernel sends
@ -71,7 +71,7 @@ the response via UHID_GET_REPORT_REPLY and UHID_SET_REPORT_REPLY to the kernel.
The kernel blocks internal driver-execution during such round-trips (times out
after a hard-coded period).
If your device disconnects, you should send an UHID_DESTROY event. This will
If your device disconnects, you should send a UHID_DESTROY event. This will
unregister the device. You can now send UHID_CREATE2 again to register a new
device.
If you close() the fd, the device is automatically unregistered and destroyed
@ -125,7 +125,7 @@ UHID_START:
This is sent when the HID device is started. Consider this as an answer to
UHID_CREATE2. This is always the first event that is sent. Note that this
event might not be available immediately after write(UHID_CREATE2) returns.
Device drivers might required delayed setups.
Device drivers might require delayed setups.
This event contains a payload of type uhid_start_req. The "dev_flags" field
describes special behaviors of a device. The following flags are defined:
@ -149,7 +149,7 @@ UHID_STOP:
reloaded/changed the device driver loaded on your HID device (or some other
maintenance actions happened).
You can usually ignored any UHID_STOP events safely.
You can usually ignore any UHID_STOP events safely.
UHID_OPEN:
This is sent when the HID device is opened. That is, the data that the HID
@ -166,17 +166,17 @@ UHID_OUTPUT:
This is sent if the HID device driver wants to send raw data to the I/O
device on the interrupt channel. You should read the payload and forward it to
the device. The payload is of type "struct uhid_output_req".
This may be received even though you haven't received UHID_OPEN, yet.
This may be received even though you haven't received UHID_OPEN yet.
UHID_GET_REPORT:
This event is sent if the kernel driver wants to perform a GET_REPORT request
on the control channeld as described in the HID specs. The report-type and
on the control channel as described in the HID specs. The report-type and
report-number are available in the payload.
The kernel serializes GET_REPORT requests so there will never be two in
parallel. However, if you fail to respond with a UHID_GET_REPORT_REPLY, the
request might silently time out.
Once you read a GET_REPORT request, you shall forward it to the hid device and
remember the "id" field in the payload. Once your hid device responds to the
Once you read a GET_REPORT request, you shall forward it to the HID device and
remember the "id" field in the payload. Once your HID device responds to the
GET_REPORT (or if it fails), you must send a UHID_GET_REPORT_REPLY to the
kernel with the exact same "id" as in the request. If the request already
timed out, the kernel will ignore the response silently. The "id" field is
@ -184,7 +184,7 @@ UHID_GET_REPORT:
UHID_SET_REPORT:
This is the SET_REPORT equivalent of UHID_GET_REPORT. On receipt, you shall
send a SET_REPORT request to your hid device. Once it replies, you must tell
send a SET_REPORT request to your HID device. Once it replies, you must tell
the kernel about it via UHID_SET_REPORT_REPLY.
The same restrictions as for UHID_GET_REPORT apply.