Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752034Ab2KSLFo (ORCPT ); Mon, 19 Nov 2012 06:05:44 -0500 Received: from mx2.promwad.com ([195.222.87.218]:22627 "EHLO mx2.promwad.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751459Ab2KSLFm convert rfc822-to-8bit (ORCPT ); Mon, 19 Nov 2012 06:05:42 -0500 X-Greylist: delayed 324 seconds by postgrey-1.27 at vger.kernel.org; Mon, 19 Nov 2012 06:05:42 EST From: Kurachkin Michail To: Greg Kroah-Hartman CC: "linux-kernel@vger.kernel.org" , Kuten Ivan , Josh Triplett Subject: RE: TDM bus support in Linux Kernel Thread-Topic: TDM bus support in Linux Kernel Thread-Index: AQHM4lI1DORXVh0dc0+QjrL9WppqRJYqzy4AgcN9PO4= Date: Mon, 19 Nov 2012 11:00:12 +0000 Message-ID: References: ,<20120203110036.GA7732@leaf> In-Reply-To: <20120203110036.GA7732@leaf> Accept-Language: en-US, ru-RU Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [192.168.10.130] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6139 Lines: 135 Hi Greg, During the work on developing VoIP network router I designed TDM bus subsystem and wrote SLIC driver for si3226x. This code was developed for the commercial project, and now I am willing to release it under GPL. Please review my sources (or give me a clue on what to do next) and give some feedback on my work. https://github.com/stelhs/slic_tdm.git Some technical delails on my project: SOHO network router with VoIP based on CPU ARM9 Marvell 88F6283. Router contains two FXS ports based on Silabs si32260 which is connected to CPU with SPI and TDM buses. Description of the TDM subsystem: The code which registers new TDM bus: /drivers/tdm/tdm_code.c /include/linux/tdm/tdm.h TDM subsystem provides API for registering of various TDM controller drivers: tdm_alloc_controller() - alloc memory for TDM controller driver tdm_free_controller() - free memory allocated for TDM controller driver tdm_controller_register() - register TDM controller driver on TDM bus tdm_controller_unregister() - unregister TDM controller driver tdm_alloc_voice_channel() - allocate memory for voice channel tdm_register_new_voice_channel() - register voice channel on TDM controller tdm_free_voice_channels() - unregister and free voice channels tdm_register_board_info() - register TDM devices list from board_specific code TDM controller driver attached to TDM bus. Provides the following API for TDM device drivers: tdm_new_device() - allocate memory and create tdm_device tdm_add_device() - add tdm device to TDM bus request_voice_channel() - attempt to request TDM voice channel for TDM device release_voice_channel() - release TDM voice channel tdm_run_audio() - enable audio receive/transmit tdm_stop_audio() - disable audio receive/transmit tdm_recv() - receive one block audio data tdm_send() - transmit one block audio data tdm_poll_rx() - check for exist incomming data tdm_poll_tx() - check free space for transmitting data tdm_get_voice_block_size() - return audio block size TDM controller driver for ARM Marvell kirkwood CPU. Was tested on CPU ARM9 Marvell 88F6283. This CPU supports two TDM audio channels. /drivers/tdm/kirkwood_tdm.c /drivers/tdm/kirkwood_tdm.h Driver for SLIC Silabs si3226x based on SPI and TDM frameworks. /drivers/staging/si3226x/si3226x_drv.c /drivers/staging/si3226x/si3226x_hw.c Provides two FXS channels and creates the following device files: /dev/si3226x_cnt.x /dev/si3226x_fxs0.x /dev/si3226x_fxs1.x Regards, Kurochkin Michail Software Engineer Promwad Innovation Company www.promwad.com ________________________________________ From: Josh Triplett [josh@joshtriplett.org] Sent: Friday, February 03, 2012 13:00 To: Palstsiuk Viktar Cc: linux-kernel@vger.kernel.org; alsa-devel@alsa-project.org; Kurachkin Michail; Kuten Ivan Subject: Re: TDM bus support in Linux Kernel On Fri, Feb 03, 2012 at 11:59:10AM +0300, Viktar Palstsiuk wrote: > We are designing custom hardware board where processor is connected > with analog telephony > SLIC via TDM bus. > During investigation of Linux kernel we did not find any corresponding TDM code. > So decided to write a new TDM subsystem in drivers/tdm (like SPI). > The subsystem consists of tdm_core.c which implements TDM bus routines, > e.g. tdm_register_board_info(), tdm_add_device(), > tdm_controller_register() etc, and > someplatform_tdm.c which implements platform specific TDM contoller. > > Any suggestion if we have chosen right direction and our approach > conforms Linux kernel architecture? Disclaimer: not a telephony expert. >From the information you've provided in this mail, it *sounds* like you probably have the right approach. You've definitely done the right thing by asking for architectural review sooner rather than later, and it sounds like you've created a nicely abstracted subsystem modeled after existing Linux subsystems rather than building an entire stack directly into your driver, which would already put you well ahead of most hardware vendors. :) You should post your code to LKML so that developers can review it. You should also CC any potentially interested developers, so they actually see it. In addition to CCing anyone specifically interested in telephony, since you've developed a new subsystem I'd suggest CCing Greg Kroah-Hartman as the maintainer of the driver core. Also, I don't know whether the TDM bus allows device probing or whether you have to magically know in advance what devices you expect on a particular platform. If the former, you probably want to make sure you support and use an appropriate MODULE_DEVICE_TABLE for your drivers, so you can easily look up the right driver for any given device. If the latter, you may potentially want to look into the "flattened device tree" mechanism, which provides a standard means of providing "hardcoded" hardware configuration information to the kernel at boot time. If as the maker of the hardware you have any control over this, go with the former. :) > May be there were already some preliminary work for this? In-kernel, it looks like a "slicoss" driver exists in staging, and drivers/isdn exists, but AFAICT neither one has had any non-bugfix development in a long time; the latter has some references to TDM, though I don't know to what extent it might prove relevant to you. Outside the kernel, you may want to look at http://wiki.freeswitch.org/wiki/FreeTDM ; it currently seems to rely on various out-of-tree and proprietary drivers of dubious status, but you might still want to look it over, to find out if it has useful ideas or if you might want to add support for your hardware. I don't know of any efforts specifically trying to provide a standardized interface for the TDM bus. I suspect you'll end up getting to lead the way here. Hope that helps, Josh Triplett -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/