Declare sched_active_thread and sched_active_pid locally in the ESP code for
now. Once the code is cleaned up to no longer tap into scheduler internals but
use the API instead, those can be dropped again.
Similar to the cortex-m common linker scripts, the RISC-V linker scripts
can be unified easily, requiring only the memory addresses and lengths.
This simplifies adding new RISC-V CPU's later
This changes the prefixes of the symbols generated from USEMODULE and
USEPKG variables. The changes are as follow:
KCONFIG_MODULE_ => KCONFIG_USEMODULE_
KCONFIG_PKG_ => KCONFIG_USEPKG_
MODULE_ => USEMODULE_
PKG_ => USEPKG_
Using the TER bit in the TX descriptors when only using a single descriptor for
sending triggered a hardware bug. Thus, stop using the TER bit and store the
currently active TX descriptor in RAM instead.
The Watchdog on the CC2538 only supports 4 intervals (2ms, 16ms, 250ms & 1s).
Since the watchdog timer API specifies a `max_time`, the interval equal or
below that time is selected.
E.g. for `max_time=125ms` the 16ms interval would be selected.
This is outside the tolerance of the `tests/periph_wdt` test.
Co-authored-by: Thomas Geithner <thomas.geithner@dai-labor.de>
The rv32imac supports the A (atomic) extensions containing
read-modify-store operations. This commit modifies the GPIO code to use
these for all bitwise operations. The atomic operations are emitted with
relaxed ordering as they do not require multiprocessor synchronization.
This decreases the duration of the gpio operations from 59 ns to 50 ns
per call. depending a bit on the type of operation.
This is a small optimization to the RISC-V trap handler. By splitting
the call to sched_run from the trap_handle call, loading the previous
thread ptr can be delayed until after it is determined that a schedule
run is required. This shaves of a few cycles during regular interrupts
that do not trigger the scheduler.
This commit reworks the trap entry to only save the callee-saved
registers when a context switch is required. the caller-saved registers
are always stored and restored to adhere to the RISC-V ABI. This saves
considerable cycles on interrupts.
