On ARMC6 with optimization level "-Os", the two functions NVIC_SetVector/NVIC_GetVector
will be translated to illegal instruction for trapping due to NVIC_FLASH_VECTOR_ADDRESS
defined as direct 0. Fixed by defining NVIC_FLASH_VECTOR_ADDRESS as a symbol instead to
avoid such optimization error.
On NUC472, on wake-up from power-down mode, we may meet hard fault or some other
unknown error. Before its cause is found, we enter idle mode instead for a workaround.
To simulate power-down mode with idle mode, we also disable us_ticker during
power-down period.
Instead of user defined symbols in assembly files or C files,
use linker scripts to add heap and stack - this is inconsistent
with ARM std linker scripts
Nuvoton M2351 was including generic core_armv8mbl.h from CMSIS - we
need it to be more specific to identify the specific core for
wait_ns. Change to core_cm23.h.
Port of NUC472/M487 crypto AC mgmt work to M2351:
1. Choose mutex to synchronize access to crypto non-SHA AC
2. Choose atomic flag to synchronize access to crypto SHA AC
1. For SHA AC, use atomic flag to manage its ownership.
(1) Nuvoton SHA AC doesn't support SHA context save & restore, so S/W
SHA fallback has been supported before. To make non-blocking 'acquire'
semantics clearer, introduce 'try_acquire' to substitute for 'acquire'.
(2) No biting CPU due to mechanism above.
(3) No deadlock due to mechanism above.
2. For AES/DES/ECC AC, change to mutex to manage their ownership.
(1) Change crypto-misc.c to crypto-misc.cpp to utilize C++ SingletonPtr
which guarantees thread-safe mutex construct-on-first-use.
(2) With change to crypto-misc.cpp, add 'extern "C"' modifier to CRYPTO_IRQHandler()
to avoid name mangling in C++.
(3) No priority inversion because mutex has osMutexPrioInherit attribute
bit set.
(4) No deadlock because these AC are all locked for a short sequence
of operations rather than the whole lifetime of mbedtls context.
(5) For double mbedtls_internal_ecp_init() issue, it has been fixed in upper
mbedtls layer. So no need to change ecc init/free flow.
With support for checking H/W UART initialized or not, we can simplify stdio management:
1. When serial_init(&stdio_uart) calls in, just set the 'stdio_uart_inited' flag.
2. When serial_free(&stdio_uart) calls in, just clear the 'stdio_uart_inited' flag.
Except above, we needn't make special handling with 'stdio_uart'.