From 356006a6cfb750f094b773ad8276c428887e5142 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Mon, 28 Dec 2020 12:53:27 -0800 Subject: [PATCH] Documentation: HID: uhid editing & corrections 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 Cc: Jiri Kosina Cc: Benjamin Tissoires Cc: linux-input@vger.kernel.org Cc: David Herrmann Cc: Jonathan Corbet Cc: linux-doc@vger.kernel.org Cc: Jonathan Cameron Reviewed-by: Jonathan Cameron Signed-off-by: Jiri Kosina --- Documentation/hid/uhid.rst | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-) diff --git a/Documentation/hid/uhid.rst b/Documentation/hid/uhid.rst index b18cb96c885f..2243a6b75914 100644 --- a/Documentation/hid/uhid.rst +++ b/Documentation/hid/uhid.rst @@ -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.