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path: root/drivers/hid/uhid.c
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2012-07-20HID: uhid: Fix sending events with invalid dataVinicius Costa Gomes
This was detected because events with invalid types were arriving to userspace. The code before this patch would only work for the first event in the queue (when uhid->tail is 0). Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org> Reviewed-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: silence gcc warningJiri Kosina
gcc is giving me: drivers/hid/uhid.c: In function ‘uhid_hid_get_raw’: drivers/hid/uhid.c:157: warning: ‘len’ may be used uninitialized in this function which is clearly bogus, as - when used as memcpy() argument, it's initialized properly - the code is structured in a way that either 'ret' or 'len' is always initialized, so the return statement always has an initialized value. Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: implement feature requestsDavid Herrmann
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>
2012-06-18HID: uhid: forward raw output reports to user-spaceDavid Herrmann
Some drivers that use non-standard HID features require raw output reports sent to the device. We now forward these requests directly to user-space so the transport-level driver can correctly send it to the device or handle it correspondingly. There is no way to signal back whether the transmission was successful, moreover, there might be lots of messages coming out from the driver flushing the output-queue. However, there is currently no driver that causes this so we are safe. If some drivers need to transmit lots of data this way, we need a method to synchronize this and can implement another UHID_OUTPUT_SYNC event. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: forward output request to user-spaceDavid Herrmann
If the hid-driver wants to send standardized data to the device it uses a linux input_event. We forward this to the user-space transport-level driver so they can perform the requested action on the device. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: forward open/close events to user-spaceDavid Herrmann
HID core notifies us with *_open/*_close callbacks when there is an actual user of our device. We forward these to user-space so they can react on this. This allows user-space to skip I/O unless they receive an OPEN event. When they receive a CLOSE event they can stop I/O again to save energy. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: add UHID_START and UHID_STOP eventsDavid Herrmann
We send UHID_START and UHID_STOP events to user-space when the HID core starts/stops the device. This notifies user-space about driver readiness and data-I/O can start now. This directly forwards the callbacks from hid-core to user-space. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: forward hid report-descriptor to hid coreDavid Herrmann
When the uhid_hid_parse callback is called we simply forward it to hid_parse_report() with the data that we got in the UHID_CREATE event. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: allow feeding input data into uhid devicesDavid Herrmann
This adds a new event type UHID_INPUT which allows user-space to feed raw HID reports into the HID subsystem. We copy the data into kernel memory and directly feed it into the HID core. There is no error handling of the events couldn't be parsed so user-space should consider all events successfull unless read() returns an error. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: add UHID_CREATE and UHID_DESTROY eventsDavid Herrmann
UHID_CREATE and UHID_DESTROY are used to create and destroy a device on an open uhid char-device. Internally, we allocate and register an HID device with the HID core and immediately start the device. From now on events may be received or sent to the device. The UHID_CREATE event has a payload similar to the data used by Bluetooth-HIDP when creating a new connection. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: implement write() on uhid devicesDavid Herrmann
Similar to read() you can only write() a single event with one call to an uhid device. To write multiple events use writev() which is supported by uhid. We currently always return -EOPNOTSUPP but other events will be added in later patches. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: implement read() on uhid devicesDavid Herrmann
User-space can use read() to get a single event from uhid devices. read() does never return multiple events. This allows us to extend the event structure and still keep backwards compatibility. If user-space wants to get multiple events in one syscall, they should use the readv()/writev() syscalls which are supported by uhid. This introduces a new lock which helps us synchronizing simultaneous reads from user-space. We also correctly return -EINVAL/-EFAULT only on errors and retry the read() when some other thread captured the event faster than we did. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: allow poll()'ing on uhid devicesDavid Herrmann
As long as the internal buffer is not empty, we return POLLIN to user-space. uhid->head and uhid->tail are no atomics so the comparison may return inexact results. However, this doesn't matter here as user-space would need to poll() in two threads simultaneously to trigger this. And in this case it doesn't matter if a cached result is returned or the exact new result as user-space does not know which thread returns first from poll() and the following read(). So it is safe to compare the values without locking. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: add internal message bufferDavid Herrmann
When receiving messages from the HID subsystem, we need to process them and store them in an internal buffer so user-space can read() on the char device to retrieve the messages. This adds a static buffer for 32 messages to each uhid device. Each message is dynamically allocated so the uhid_device structure does not get too big. uhid_queue() adds a message to the buffer. If the buffer is full, the message is discarded. uhid_queue_event() is an helper for messages without payload. This also adds a public header: uhid.h. It contains the declarations for the user-space API. It is built around "struct uhid_event" which contains a type field which specifies the event type and each event can then add a variable-length payload. For now, there is only a dummy event but later patches will add new event types and payloads. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-18HID: uhid: introduce user-space I/O driver support for HIDDavid Herrmann
This adds a dummy driver that will support user-space I/O drivers for the HID subsystem. This allows to write transport-level drivers like USB-HID and Bluetooth-HID in user-space. Low-Energy Bluetooth needs this to feed HID data that is parsed in user-space back into the kernel. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>