suspect-devices/circuitpython/ports/nrf/supervisor/port.c, branch encoding

nRF: Always use sd_nvic_critical_region calls

2020-07-15T14:26:47+00:00

The motivation for doing this is so that we can allow common_hal_mcu_disable_interrupts in IRQ context, something that works on other ports, but not on nRF with SD enabled. This is because when SD is enabled, calling sd_softdevice_is_enabled in the context of an interrupt with priority 2 or 3 causes a HardFault. We have chosen to give the USB interrupt priority 2 on nRF, the highest priority that is compatible with SD. Since at least SoftDevice s130 v2.0.1, sd_nvic_critical_region_enter/exit have been implemented as inline functions and are safe to call even if softdevice is not enabled. Reference kindly provided by danh: https://devzone.nordicsemi.com/f/nordic-q-a/29553/sd_nvic_critical_region_enter-exit-missing-in-s130-v2 Switching to these as the default/only way to enable/disable interrupts simplifies things, and fixes several problems and potential problems: * Interrupts at priority 2 or 3 could not call common_hal_mcu_disable_interrupts because the call to sd_softdevice_is_enabled would HardFault * Hypothetically, the state of sd_softdevice_is_enabled could change from the disable to the enable call, meaning the calls would not match (__disable_irq() could be balanced with sd_nvic_critical_region_exit). This also fixes a problem I believe would exist if disable() were called twice when SD is enabled. There is a single "is_nested_critical_region" flag, and the second call would set it to 1. Both of the enable() calls that followed would call critical_region_exit(1), and interrupts would not properly be reenabled. In the new version of the code, we use our own nesting_count value to track the intended state, so now nested disable()s only call critical_region_enter() once, only updating is_nested_critical_region once; and only the second enable() call will call critical_region_exit, with the right value of i_n_c_r. Finally, in port_sleep_until_interrupt, if !sd_enabled, we really do need to __disable_irq, rather than using the common_hal_mcu routines; the reason why is documented in a comment.

nrf: add ticks (not subticks) to overflow count during reset

2020-05-27T03:28:50+00:00

Signed-off-by: Sean Cross

nrf: port: save rtc value across reboots

2020-05-27T03:28:49+00:00

As part of the reset process, save the current tick count to an uninitialized memory location. That way, the current tick value will be preserved across reboots. A reboot will cause us to lose a certain number of ticks, depending on how long a reboot takes, however if reboots are infrequent then this will not be a large amount of time lost. Signed-off-by: Sean Cross

nrf: reset watchdog as part of port_reset()

2020-05-27T03:28:49+00:00

Signed-off-by: Sean Cross

nrf: boot into safe mode sometimes for watchdog reset

2020-05-27T03:28:49+00:00

If the watchdog resets the system and we're plugged into USB, boot into safe mode. Signed-off-by: Sean Cross

nrf: port: add memory barrier before wfi

2020-05-21T13:46:37+00:00

ARM recommends issuing a DSB instruction propr to issuing WFI, as it is required on many parts suchas Cortex-M7. This is effectively a no-op on the Cortex-M4 used in most NRF parts, however it ensures that we won't be surprised when new parts come out. See http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dai0321a/BIHICBGB.html for more information. Signed-off-by: Sean Cross

nrf: disable interrupts before running wfi

2020-05-21T13:43:52+00:00

In order to ensure we don't have any outstanding requests, disable interrupts prior to issuing `WFI`. As part of this process, check to see if there are any pending USB requests, and only execute the `WFI` if there is no pending data. This fixes #2855 on NRF. Signed-off-by: Sean Cross

Merge pull request #2932 from simmel-project/nrf-rtc-reset

2020-05-20T18:39:16+00:00

nrf: reset rtc as part of port_reset()

2020-05-20T08:44:18+00:00

On NRF, the `rtc_reset()` function is never called. As a result, calls to `time.time()` return a cryptic error> ``` >>> import time >>> time.time() '' object has no attribute 'datetime' >>> ``` This is because `MP_STATE_VM(rtc_time_source)` is not initialized due to `rtc_reset()` never being called. If `CIRCUITPY_RTC` is enabled, call `rtc_reset()` as part of the `reset_port()` call. This ensures that `time.time()` works as expected. Signed-off-by: Sean Cross

Merge remote-tracking branch 'adafruit/master' into esp32s2

2020-05-18T23:46:41+00:00