To change TRNG security state, we need to:
1. Change CRPT/CRYPTO bit in NVIC/SCU in partition_M2351.h
2. Add/remove TRNG in device_has list in targets.json to match partition_M2351.h
NSC location has the following requirements:
1. By IDAU, 0~0x4000 is secure. NSC can only locate in 0x4000~0x10000000.
2. Greentea flash IAP uses last 4 sectors for its test. Avoid this range.
3. Greentea NVSTORE uses last 2 sectors or 4KB x 2 for its test. Avoid this range.
In Mbed OS, page size is program unit, which is different than FMC definition.
After fixing page size, we can pass NVSTORE test (mbed-os-features-nvstore-tests-nvstore-functionality).
1. Replace SYS_ResetModule/CLK_SetModuleClock/CLK_EnableModuleClock/CLK_DisableModuleClock with TrustZone-aware versions.
2. Configure all UART to secure
3. Support asynchronous transfer
4. Remove sleep management code, which has been replaced with Sleep Manager.
The rework includes the following:
1. Remove ticker overflow handling because upper layer (mbed_ticker_api.c) has done with it.
This makes us_ticker/lp_ticker implementation more succinct and avoids potential error.
2. Refine timer register access with low-power clock source
1. Revise NU_PORT_BASE to be TrustZone-aware
2. Add TrustZone-aware NU_GET_GPIO_PIN_DATA/NU_SET_GPIO_PIN_DATA to replace GPIO_PIN_DATA
3. Revise pin_function to be TrustZone-aware
All modules are configured to non-secure except:
1. TIMER0/1 hard-wired to secure and TIMER2/3 reserved for non-secure.
2. PDMA0 hard-wired to secure and PDMA1 reserved for non-secure.
3. RTC configured to secure and shared to non-secure through NSC.
4. CRYPTO configured to secure and shared to non-secure through NSC.
As per SAU documents, SAU is always present if the security extension is
available. The functionality differs if the SAU contains SAU regions.
If SAU regions are available it is configured with the macro __SAUREGION_PRESENT