Squashed commit of the following:
Add procfs support to show stopped tasks. Add nxsig_action() to solve a chicken and egg problem: We needed to use sigaction to set default actions, but sigaction() would refuse to set actions if the default actions could not be caught or ignored.
sched/signal: Add configuration option to selectively enabled/disable default signal actions for SIGSTOP/SIGSTP/SIGCONT and SIGKILL/SIGINT. Fix some compilation issues.
sched/sched: Okay.. I figured out a way to handle state changes that may occur while they were stopped. If a task/thread was already blocked when SIGSTOP/SIGSTP was received, it will restart in the running state. I will appear that to the task/thread that the blocked condition was interrupt by a signal and returns the EINTR error.
sched/group and sched/sched: Finish framework for continue/resume logic.
sched/signal: Roughing out basic structure to support task suspend/resume
drivers/serial/Kconfig: It is no longer necessary to restrict Ctrl-C handling to the FLAT build
sched/signal: Add a new configuration option to select signal default actions, separate handling of signal default actions from both task startup logic and from the serial TTY Ctrl-C logic. Add a signal set in the group structure to keep track of what signals have been set to the default action. In dispatching signals in PROTECTED or KERNEL mode, use this signal set to determine if the default signal handler is attached and dispatch the signal in kernel mode for the default actions.
drivers/serial: Add Ctrl-C/Ctrl-X support. This is an initial working implementation that still requires that several details be resolved.
sched/task/task_start.c: Add default signal action to SIGKILL.
Squashed commit of the following:
arch/arm/src/lpc54xx: Finish off some missing logic. Complete now execpt for GPIO and LED support.
arch/arm/src/lpc54xx: Add lpc54_clrpend.c
arch/arm/src/lpc54xx: Serial driver is complete and compiles.
arch/arm/src/lpc54xx: Add beginning of a serial driver (still missing some logic)
arch/arm/src/lpc54xx: Fleshes out low level USART intialization.
arch/arm/src/lpc546xx/Kconfig: Add hooks to integrate with common seril upper half.
arch/arm/src/lpc54xx: Beginning of USART console support.
arch/arm/src/lpc54xx: Completes very basic clock configuration.
arch/arm/src/lpc54xx: Add clocking logic (still not complete)
arch/arm/src/lpc54xx: Beginning of PLL configuration logic.
arch/arm/src/lpc54xx: Fix a few things from first compile attempt. Compilation cannot work until I at least finish the clock configuration logic.
arch/arm/src/lpc54xx: Addes some SysTick logic.
arch/arm/src/lpc54xx: Completes basic startup logic (sans clock configuration) and interrupt configuration.
arch/arm/src/lpc54xx: Add generic ARMv7-M start-up logic (needs LPC54628 customizations); add emtpy file that will eventually hold the clock configuration logic.
arch/arm/src/lpc54xx: Add (incomplete) SYSCON register definition header file.
arch/arm/src/lpc54xx: Add FLEXCOMM header file.
arch/arm/src/lpc54xx: Bring in tickless clock logic from LPC43; configs/lpcxpresso-lpc54628: mount procfs if enabled.
arch/arm/src/lpc54xx: Add RIT clock definitions; add SysTick initialization (not finished)
LPC54xx and LPCXpresso-LPC54628: add more boilerplate files and stubbed out files.
arch/arm/src/lpc54xx: Add (incomplete) USART header file.
Add another condition to a Kconfig; refresh a defconfig.
arch/arm/src/lpc54xx/chip: Add LPC54628 memory map header files.
configs/lpcxpresso-lpc54628: Add basic build files for the LPCXpresso-LPC54628
arch/: Basic build directory structure for the LPC54628
