# HG changeset patch # User Mychaela Falconia # Date 1541582183 0 # Node ID 9582a626345c58330662cce29412f4427683d7c9 # Parent 7c68000b87cf6e6fabb058ca64487e552ffc2176 rm doc/C155-target "won't support it" note diff -r 7c68000b87cf -r 9582a626345c doc/C155-target --- a/doc/C155-target Wed Nov 07 06:55:49 2018 +0000 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,64 +0,0 @@ -In the early years of FreeCalypso, when we made our first attempt at FC GSM -firmware that was eventually retired under the name Citrine, we supported -running that fw on the Mot C155/156 target in addition to the other two C1xx -subfamilies. However, that C155 target support in not available in our current -Magnetite and Selenite firmwares. We are not doing any work to support that -target in our current fw because it does not provide anything of value that is -not better provided by other targets: - -* If your goal is to have a practically usable phone, the simpler C139/140 is a - better choice than C155/156: C155 uses a ringtone generator chip for which no - docs could be found, thus we may not be able to make it ring (in contrast, - C139 uses a piezoelectric buzzer driven by the Calypso itself), and C155's - LCD controller is much less obvious than the one in the C139 - the latter - already works the way we like. - -* If instead you would like a platform for playing with non-UI modem firmware - (which is all that our previous Citrine fw provided), then the only platform - which we officially support and endorse for that purpose is our own FCDEV3B. - It is not reasonable at this point to ask us to expend unpaid volunteer time - to support a hardware platform that is not made or sold by us when instead - you should be supporting our work by buying the hardware which we do make. - -If you wish to strike out on your own and try to resurrect C155 target support -in FC Selenite or Magnetite, your first difficulty will be that you won't be -able to run our fw entirely out of RAM without flashing like we did when running -Citrine on this target. FC Citrine implemented an FFS-in-RAM hack as an -alternative to using a real FFS in flash, but this hack is not present in -Magnetite or Selenite, thus unless you go even further out and resurrect that -hack as well, you will have to flash your firmware. If you take the route of -flashing your fw, you will have to decide between one of two possible -approaches: - -Approach 1: you can keep this target's original bootloader that expects the -main fw image to begin at 0x20000 with a hand-off interface that is new to the -C155 (different from the more basic C1xx subfamilies), and build your fw to fit -this C155 boot interface. This approach was supported in Citrine (although not -actually used because it was much easier to run via fc-xram w/o flashing) and -can be easily resurrected in the gcc build of Selenite. However, it would be a -lot more difficult to get this approach to work with TI's original TMS470 -environment: doing so would require major surgery on their assembly code and -linker script magic, which I am not comfortable with because we have no docs or -sources for those assembler and linker tools. You will also face the same -problem if you resurrect our old FFS-in-RAM hack and try to build a fw image -that runs entirely out of RAM w/o flashing: it is easy to do in the gcc -environment, but not in TMS470. - -Approach 2: you can replace the bootloader with the one we use on the more -basic C1xx phones (compal-flash-boot-for-fc.bin), in which case you will have -complications with loadtools (the ARM vs. Thumb entry point difference for -serially loaded code), but you can work around that issue by running fc-loadtool -and fc-xram with -h c155 -c plain instead of just -h c155 after you change the -bootloader, or you can create yet another patched bootloader version that does -the Thumb entry point for serially loaded code like C155 original but hands off -to the main fw in flash in the older C1xx fashion. Either way you will then be -able to build flashable fw images for this boot-modified C155 in the same manner -as how we do it for the more basic C1xx targets, and thus have both TMS470 and -gcc environments. - -As you can see from the above, it will be messy and unpleasant no matter which -way you lick it, and we (FreeCalypso Central) are not going to do this work for -free, whereas doing it on a commercial consulting basis would cost a lot more -than the $500 USD retail price of our own FreeCalypso development board -(FCDEV3B) that avoids all of these problems and is a much nicer platform for -Calypso sw/fw development.