This introduces KCONFIG_BOARD_CONFIG and KCONFIG_CPU_CONFIG variable for
boards and CPUs (including common directories) to add default
configuration files to be merged. The current approach, as it uses
Makefile.features, would include boards first, not allowing them to
override CPU configurations.
stm32f1 periph_rtc implementation gets a 1s resolution by dividing
CLOCK_LSx by 32768. This only make sense if CLOCK_LSE is set,
otherwise CLOCK_LSI=~40000, which will lead to an imprecise rtc.
Use the new OPENOCD_RESET_USE_CONNECT_ASSERT_SRST to configure
'reset_config connect_assert_srst' when flashing and resetting only.
This removes the need for a special debug configuration and should allow
connecting to a running target again.
cpu/$(CPU)/Makefile.features and cpu/$(CPU)/Makefile.dep are
automatically included
Part of moving CPU/CPU_MODEL definition to Makefile.features to have it
available before Makefile.include.
Currently only tested boards provide the feature riotboot.
Potentially all boards embeding a cortex-m0+/3/4/7 are
able to have riotboot as a feature, but other dependencies
need to be met, e.g. usage of cortexm.ld linker script,
double initialisation of cpu_init(), etc. See doc in
bootloaders/riotboot.
iotlab-m3 boards always ended up not being able to flash after time.
This changes managed to fix and flash boards that where able to be flashed with
the deprecated `ft2232` driver and not with the `ftdi` driver used in RIOT.
It combines configuration from openocd, iot-lab, RIOT config and Alexandre
Abadie feedback
* http://repo.or.cz/openocd.git/blob/HEAD:/tcl/interface/ftdi/iotlab-usb.cfg
* ftdi configuration
* https://github.com/iot-lab/iot-lab-gateway/blob/2.4.1/gateway_code/static/iot-lab-m3.cfg
* `trst_and_srst` config
* Alexandre feedback and http://openocd.org/doc/html/Reset-Configuration.html
* 'connect_assert_srst' reset configuration
* it prevents errors in the output on first flash
* should help on boards with invalid code
* It was taken from what Alexandre found for board 'b-l072z-lrwan1'
* It requires using '-c reset halt' instead of '-c halt' before debug
* RIOT
* Keep the `configure -rtos` auto
