From fcfcf0deb89ece6eb9ae23768fec1bc1718f9b7f Mon Sep 17 00:00:00 2001 From: David Herrmann Date: Sun, 10 Jun 2012 15:16:25 +0200 Subject: 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 Signed-off-by: Jiri Kosina --- include/linux/uhid.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'include/linux/uhid.h') diff --git a/include/linux/uhid.h b/include/linux/uhid.h index 2c972550a624..9c6974f16966 100644 --- a/include/linux/uhid.h +++ b/include/linux/uhid.h @@ -32,6 +32,8 @@ enum uhid_event_type { UHID_OUTPUT, UHID_OUTPUT_EV, UHID_INPUT, + UHID_FEATURE, + UHID_FEATURE_ANSWER, }; struct uhid_create_req { @@ -73,6 +75,19 @@ struct uhid_output_ev_req { __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; @@ -81,6 +96,8 @@ struct uhid_event { 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__)); -- cgit v1.2.3