Timer driver refactoring

[digitalentity]

Code simplification, de-duplication and better timer driver abstraction.
Work in progress. Seems to work well on REVO

[digitalentity]

Despite the fact that now all timers present on the CPU are included into the code (previously they were guarded by USED_TIMERS) code didn't became much bigger:

Before:

arm-none-eabi-size ./obj/main/inav_REVO.elf
   text    data     bss     dec     hex filename
 211416    5528   40648  257592   3ee38 ./obj/main/inav_REVO.elf
arm-none-eabi-objcopy -O ihex --set-start 0x8000000 obj/main/inav_REVO.elf obj/inav_2.0.0_REVO.hex

After:

arm-none-eabi-size ./obj/main/inav_REVO.elf
   text    data     bss     dec     hex filename
 211468    5528   40984  257980   3efbc ./obj/main/inav_REVO.elf
arm-none-eabi-objcopy -O ihex --set-start 0x8000000 obj/main/inav_REVO.elf obj/inav_2.0.0_REVO.hex

[digitalentity]

Rebased, tested on REVO

[digitalentity]

Size before:

arm-none-eabi-size ./obj/main/inav_OMNIBUSF7NXT.elf
   text    data     bss     dec     hex filename
 240876    9804   43792  294472   47e48 ./obj/main/inav_OMNIBUSF7NXT.elf

After:

arm-none-eabi-size ./obj/main/inav_OMNIBUSF7NXT.elf
   text    data     bss     dec     hex filename
 240764    9804   44776  295344   481b0 ./obj/main/inav_OMNIBUSF7NXT.elf

Timer tables are bigger - they now store all timers available on the CPU, not the used ones as before. But simpler and cleaner general timer code pays back - flash usage is not bigger.

[fiam]

There's +1K in BSS on F7 and +500 on F3, looks like from the globals in timer.c. Is there any easy way to make them readonly so they can use TEXT instead? Maybe we could automatically generate the code for timer metadata, since it has to be done only one per MCU.

[digitalentity]

It's the timer run-time state that eats up bss. Maybe it's time to make this state dynamically allocated... State for each timer is 41 bytes (44 bytes if aligned), but it's only used when timer is configured for input (Softserial RX or PPM/PWM in).

[digitalentity]

Switched to dynamic timer state allocation. Finally dynmemory allocator is used for something 😆

[DzikuVx]

@digitalentity this is just too long ;) I trust you that if it works then it works ;)

[digitalentity]

@DzikuVx I'd appreciate if you could test if SOFTSERIAL and LEDTRIP features work for you ;)

[DzikuVx]

This I can do around Tuesday

[digitalentity]

@DzikuVx if it works for you, please go ahead and merge this. I'll be in Moscow next week and most likely will have very limited connectivity.

[digitalentity]

Ok, this is now merged. Let's see how it will work out

[stronnag]

flight tested on MATEKF405 and QUARKF4. Nothing bad happened.

[digitalentity]

Good to know, thanks for testing @stronnag