From patchwork Sat Jul 3 04:10:09 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarod Wilson X-Patchwork-Id: 109984 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter.kernel.org (8.14.4/8.14.3) with ESMTP id o634AD0S003150 for ; Sat, 3 Jul 2010 04:10:13 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750847Ab0GCEKL (ORCPT ); Sat, 3 Jul 2010 00:10:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:5263 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1749667Ab0GCEKK (ORCPT ); Sat, 3 Jul 2010 00:10:10 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o634AArT005322 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Sat, 3 Jul 2010 00:10:10 -0400 Received: from ihatethathostname.lab.bos.redhat.com (ihatethathostname.lab.bos.redhat.com [10.16.43.238]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o634A9md023544 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Sat, 3 Jul 2010 00:10:10 -0400 Received: from ihatethathostname.lab.bos.redhat.com (ihatethathostname.lab.bos.redhat.com [127.0.0.1]) by ihatethathostname.lab.bos.redhat.com (8.14.4/8.14.3) with ESMTP id o634A9xS031560 for ; Sat, 3 Jul 2010 00:10:09 -0400 Received: (from jarod@localhost) by ihatethathostname.lab.bos.redhat.com (8.14.4/8.14.4/Submit) id o634A9f2031558 for linux-media@vger.kernel.org; Sat, 3 Jul 2010 00:10:09 -0400 X-Authentication-Warning: ihatethathostname.lab.bos.redhat.com: jarod set sender to jarod@redhat.com using -f Date: Sat, 3 Jul 2010 00:10:09 -0400 From: Jarod Wilson To: linux-media@vger.kernel.org Subject: [PATCH 4/3] IR/lirc: add docbook info covering lirc device interface Message-ID: <20100703041009.GF31255@redhat.com> References: <20100601205005.GA28322@redhat.com> <20100703040530.GB31255@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20100703040530.GB31255@redhat.com> User-Agent: Mutt/1.5.20 (2009-12-10) X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Sat, 03 Jul 2010 04:10:13 +0000 (UTC) diff --git a/Documentation/DocBook/v4l/lirc_device_interface.xml b/Documentation/DocBook/v4l/lirc_device_interface.xml new file mode 100644 index 0000000..a6244ed --- /dev/null +++ b/Documentation/DocBook/v4l/lirc_device_interface.xml @@ -0,0 +1,235 @@ +LIRC Device Interface + + +
+Introduction + +The LIRC device interface is a bi-directional interface for +transporting raw IR data between userspace and kernelspace. Fundamentally, +it is just a chardev (/dev/lircX, for X = 0, 1, 2, ...), with a number +of standard struct file_operations defined on it. With respect to +transporting raw IR data to and fro, the essential fops are read, write +and ioctl. + +Example dmesg output upon a driver registering w/LIRC: +
+ $ dmesg |grep lirc_dev + lirc_dev: IR Remote Control driver registered, major 248 + rc rc0: lirc_dev: driver ir-lirc-codec (mceusb) registered at minor = 0 +
+ + +What you should see for a chardev: +
+ $ ls -l /dev/lirc* + crw-rw---- 1 root root 248, 0 Jul 2 22:20 /dev/lirc0 +
+ + + +
+LIRC read fop + +The lircd userspace daemon reads raw IR data from the LIRC chardev. The +exact format of the data depends on what modes a driver supports, and what +mode has been selected. lircd obtains supported modes and sets the active mode +via the ioctl interface, detailed at . The generally +preferred mode is LIRC_MODE_MODE2, in which packets containing an int value +describing an IR signal are read from the chardev. + +See also http://www.lirc.org/html/technical.html for more info. + + +
+LIRC write fop + +The data written to the chardev is a pulse/space sequence of integer +values. Pulses and spaces are only marked implicitly by their position. The +data must start and end with a pulse, therefore, the data must always include +an unevent number of samples. The write function must block until the data has +been transmitted by the hardware. + + +
+ LIRC ioctl fop + +The LIRC device's ioctl definition is bound by the ioctl function +definition of struct file_operations, leaving us with an unsigned int +for the ioctl command and an unsigned long for the arg. For the purposes +of ioctl portability across 32-bit and 64-bit, these values are capped +to their 32-bit sizes. + +The following ioctls can be used to change specific hardware settings. +In general each driver should have a default set of settings. The driver +implementation is expected to re-apply the default settings when the device +is closed by user-space, so that every application opening the device can rely +on working with the default settings initially. + + + + LIRC_GET_FEATURES + + Obviously, get the underlying hardware device's features. If a driver + does not announce support of certain features, calling of the corresponding + ioctls is undefined. + + + + LIRC_GET_SEND_MODE + + Get supported transmit mode. Only LIRC_MODE_PULSE is supported by lircd. + + + + LIRC_GET_REC_MODE + + Get supported receive modes. Only LIRC_MODE_MODE2 and LIRC_MODE_LIRCCODE + are supported by lircd. + + + + LIRC_GET_SEND_CARRIER + + Get carrier frequency (in Hz) currently used for transmit. + + + + LIRC_GET_REC_CARRIER + + Get carrier frequency (in Hz) currently used for IR reception. + + + + LIRC_{G,S}ET_{SEND,REC}_DUTY_CYCLE + + Get/set the duty cycle (from 0 to 100) of the carrier signal. Currently, + no special meaning is defined for 0 or 100, but this could be used to switch + off carrier generation in the future, so these values should be reserved. + + + + LIRC_GET_REC_RESOLUTION + + Some receiver have maximum resolution which is defined by internal + sample rate or data format limitations. E.g. it's common that signals can + only be reported in 50 microsecond steps. This integer value is used by + lircd to automatically adjust the aeps tolerance value in the lircd + config file. + + + + LIRC_GET_M{IN,AX}_TIMEOUT + + Some devices have internal timers that can be used to detect when + there's no IR activity for a long time. This can help lircd in detecting + that a IR signal is finished and can speed up the decoding process. + Returns an integer value with the minimum/maximum timeout that can be + set. Some devices have a fixed timeout, in that case both ioctls will + return the same value even though the timeout cannot be changed. + + + + LIRC_GET_M{IN,AX}_FILTER_{PULSE,SPACE} + + Some devices are able to filter out spikes in the incoming signal + using given filter rules. These ioctls return the hardware capabilities + that describe the bounds of the possible filters. Filter settings depend + on the IR protocols that are expected. lircd derives the settings from + all protocols definitions found in its config file. + + + + LIRC_GET_LENGTH + + Retrieves the code length in bits (only for LIRC_MODE_LIRCCODE). + Reads on the device must be done in blocks matching the bit count. + The bit could should be rounded up so that it matches full bytes. + + + + LIRC_SET_{SEND,REC}_MODE + + Set send/receive mode. Largely obsolete for send, as only + LIRC_MODE_PULSE is supported. + + + + LIRC_SET_{SEND,REC}_CARRIER + + Set send/receive carrier (in Hz). + + + + LIRC_SET_TRANSMITTER_MASK + + This enables the given set of transmitters. The first transmitter + is encoded by the least significant bit, etc. When an invalid bit mask + is given, i.e. a bit is set, even though the device does not have so many + transitters, then this ioctl returns the number of available transitters + and does nothing otherwise. + + + + LIRC_SET_REC_TIMEOUT + + Sets the integer value for IR inactivity timeout (cf. + LIRC_GET_MIN_TIMEOUT and LIRC_GET_MAX_TIMEOUT). A value of 0 (if + supported by the hardware) disables all hardware timeouts and data should + be reported as soon as possible. If the exact value cannot be set, then + the next possible value _greater_ than the given value should be set. + + + + LIRC_SET_REC_TIMEOUT_REPORTS + + Enable (1) or disable (0) timeout reports in LIRC_MODE_MODE2. By + default, timeout reports should be turned off. + + + + LIRC_SET_REC_FILTER_{,PULSE,SPACE} + + Pulses/spaces shorter than this are filtered out by hardware. If + filters cannot be set independently for pulse/space, the corresponding + ioctls must return an error and LIRC_SET_REC_FILTER shall be used instead. + + + + LIRC_SET_MEASURE_CARRIER_MODE + + Enable (1)/disable (0) measure mode. If enabled, from the next key + press on, the driver will send LIRC_MODE2_FREQUENCY packets. By default + this should be turned off. + + + + LIRC_SET_REC_{DUTY_CYCLE,CARRIER}_RANGE + + To set a range use LIRC_SET_REC_DUTY_CYCLE_RANGE/LIRC_SET_REC_CARRIER_RANGE + with the lower bound first and later LIRC_SET_REC_DUTY_CYCLE/LIRC_SET_REC_CARRIER + with the upper bound. + + + + LIRC_NOTIFY_DECODE + + This ioctl is called by lircd whenever a successful decoding of an + incoming IR signal could be done. This can be used by supporting hardware + to give visual feedback to the user e.g. by flashing a LED. + + + + LIRC_SETUP_{START,END} + + Setting of several driver parameters can be optimized by encapsulating + the according ioctl calls with LIRC_SETUP_START/LIRC_SETUP_END. When a + driver receives a LIRC_SETUP_START ioctl it can choose to not commit + further setting changes to the hardware until a LIRC_SETUP_END is received. + But this is open to the driver implementation and every driver must also + handle parameter changes which are not encapsulated by LIRC_SETUP_START + and LIRC_SETUP_END. Drivers can also choose to ignore these ioctls. + + + + +