FreeCalypso > hg > fc-magnetite
view README @ 293:5b2ebc94cae4
aci3: integrated all Openmoko AT commands except AT@BAND
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sat, 02 Sep 2017 17:37:06 +0000 |
parents | cae495752cf7 |
children | 9399a83cb394 |
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FreeCalypso Magnetite firmware project ====================================== This source tree contains yet another firmware offering created under the FreeCalypso umbrella. The key qualities of this firmware offering are: Negatives: * Builds with TI's proprietary TMS470 compiler and thus requires Wine; * Some of the fw components are still in the form of binary blobs - but see below on the deblobbing progress. Positives: * Officially supports our own FCDEV3B and Openmoko GTA01/02 modem targets, as well as "hack-only" support for Motorola C139 and Pirelli DP-L10, all from the same source tree; * Works as solidly as the TCS211 "golden" reference from TI, on all of the supported targets - deep sleep works (on non-broken hardware), voice calls work in all codec modes including AMR, the DSP dynamic download mechanism does its magic, the call audio passes reliably in both directions. The present FC Magnetite firmware is built on the principle of starting with the known working TCS211 code base, without any major restructuring, and making small incremental evolutionary changes, testing at every step to ensure that nothing breaks. It is the direct opposite of the "rebuild from the ground up" approach taken with our previous Citrine firmware aka "gsm-fw". Functionality ============= TI's GSM mobile station firmware architecture supports two ways in which the GSM device may be controlled: via AT commands from an external host and/or via a local UI on devices with LCD & keypad hardware. (I said "and/or" because the two mechanisms can coexist.) The code we got from TI (TCS211) is very solid and mature in the modem configuration (control via AT commands only, no UI, no battery management, no traditional handset on/off control), but the additional code layers that are needed for handset products but not for modems are in a very rough "proof of concept" condition, nowhere close to a usable product. The same situation currently exists in FreeCalypso Magnetite. As explained below in the Build system section, a key feature of FC Magnetite is that many different firmware configurations can be built from the same source tree. One of the configuration choices is that you can build the fw either with or without the phone UI layers. The work we have done earlier in the tcs211-c139 side project (late 2015) has been integrated into Magnetite, properly conditionalized so that TI's original configuration is fully preserved when the target != c139. However, if you build the UI-enabled configuration for any target other than Mot C139, it will compile, but it won't do anything useful: it will try to display TI's 176x220 pixel color UI on the D-Sample LCD on Calypso chip select nCS3, but this hardware doesn't exist on any of our supported targets. (The Pirelli in particular has flash on that chip select instead, so it may interfere with FFS operation.) Further work on the handset firmware configuration (UI, battery management and other currently missing functionality required for a usable phone) will have to wait until we build our own Handset Motherboard Prototype (HSMBP) with a 176x220 pixel 16-bit color LCD, replicating TI's D-Sample - I personally am not too interested in doing this handset fw work on the very crippled Mot C139 or on the Pirelli with its own host of issues, although others in the community are more than welcome to take a shot at it if someone is interested. Until then, the primary current focus of the FC Magnetite project is the AT-command-controlled modem configuration. Both TI's original modem fw (TCS211) and our recreation thereof in this Magnetite project support not only voice calls and SMS, but also CSD, fax and GPRS. This advanced functionality is fully supported on our own GSM MS development board (FCDEV3B), where both Calypso UARTs are presented directly to the developer, as well as on the embedded Calypso modem in Openmoko GTA01/02 smartphones, where the AT command channel with CSD, fax and GPRS capabilities is connected to the phone's application processor. Build system ============ Even though FC Magnetite is essentially unchanged TCS211 code base and builds using TI's proprietary TMS470 compiler under Wine, the build system is entirely new. TI's TCS211 build system, called BuSyB, works by way of a Java tool generating a customized makefile for each desired build configuration, based on lots of magic contained in a big repository of XML files. There are a bunch of Perl scripts involved as well. The Java tool that does the heavy lifting exists only as compiled Java bytecode sans source, and the surrounding Perl scripts aren't very understandable either. And the whole thing thoroughly assumes a Windows environment (drive letters, backslashes, case-insensitive file system) throughout. As a result, when working with TCS211 fw with its original build system, we had to treat these BuSyB-generated makefiles almost as being blobs in themselves: regenerating a makefile from XML magic required major effort, there were some bugs in the makefile generation which we couldn't fix and thus we had to edit the makefiles manually after each regeneration - it was an utter mess, and absolutely not an acceptable way to build a forward-looking, community- serving project. In FC Magnetite I have recreated the relevant parts of the TCS211 build system, using Bourne shell magic instead of Java and XML. Just like TI's BuSyB, ours is a makefile generation system: in order to compile the firmware in a particular desired configuration, you run a shell script to select the config you would like. This shell script will create a dedicated build directory tree to fully contain this build, and populate it with generated Makefiles and some other bits - then you go into the just-created build directory and run make there. The source and build trees are thus cleanly separated. See doc/Compiling for detailed instructions. Another key difference from our previous TCS211-based firmware offerings is that even though we still have to run TI's compiler binaries under Wine, the Wine invokation has been moved from the top (root) of the build process to the bottom leaves. With our previous TCS211-based works you would run Wine at the top, and then the entire build process would proceed in the Windows environment, using Windows versions of make and other nonsense. Not so in FC Magnetite: in this firmware project all shell scripts, Makefiles, Perl scripts and other build system accessories run at the native Unix level, and Wine is only invoked at the lowest level by individual tool wrappers: for example, TI's compiler binary cl470.exe is encapsulated in a Unix shell script called cl470 that invokes Wine to run the Windows binary, presenting the illusion of a native Unix tool to all upper levels. As yet another defenestration measure, all source files are checked into this tree with Unix line endings. Blob status =========== A long-term FreeCalypso goal is to have our phone/modem firmware rebuild fully from source without any blobs, but this goal has not been achieved yet. While we do have what *seems* to be a suitable replacement source (or feasible ability to reconstruct such) for every piece of TCS211 fw that came in binary-only form, actually making this replacement without breaking functionality is a very non-trivial endeavor. Our previous attempt to rebuild the firmware from the ground up, using source pieces lifted from different available leaks and building with gcc so that no TMS470 COFF blobs could be used - see FreeCalypso Citrine - has produced only a very limited subset of the original functionality, and until very recently even the most basic function of voice calls did not work reliably. Instead the new FreeCalypso firmware approach implemented in FC Magnetite is to approach the blob-free goal incrementally. The new Magnetite build system is specifically designed to enable the transition from the use of blobs to recompilation from source to be made with very fine granularity, down to the level of individual object modules within libs if necessary. We tackle one binary-only component at a time, either reconstructing the missing source from disassembly or adapting the source from a different version as works best in each individual case, and we make a test build of the firmware using the reconstructed or fitted component instead of the original blob. If the firmware still works (doesn't break), we make this deblobbing transition permanent and move on to the next component. See doc/Modem-configs for the current status of the deblobbing effort and for the description of the currently available configurations. Further reading =============== For various instructions and notes specific to this FreeCalypso Magnetite firmware, look in the doc directory. For more information about the overall FreeCalypso project and our hardware building aspirations, go to our website: https://www.freecalypso.org/