no-systick targets: fix systick irq handler setup

[maciejbocianski]

Description

Fix for the #11426

For targets with no H/W systick (NO_SYSTICK), SysTick_Handler needs to be remapped to specific irq emulating systick.

Pull request type

[X] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[ ] Test update
[ ] Breaking change

Reviewers

@kjbracey-arm

Release Notes

[ciarmcom]

@maciejbocianski, thank you for your changes.
@kjbracey-arm @ARMmbed/mbed-os-core @ARMmbed/mbed-os-maintainers please review.

[kjbracey]

Not following the logic of the change. Isn't this effectively just side-stepping the assert?

If NO_SYSTICK is set, SysTimer::get_irq_number should be telling us the interrupt number that is substituting for SysTick - reported by mbed_get_m0_tick_irqn().

If there is a RAM vector table, then we try to program that interrupt number for the handler we want. If there is no RAM vector table, then we check that it has been hard-coded to call the handler we want - in an RTOS build it should be hard-coded to call the RTOS tick handler.

I think your change just stops us doing the check and makes us try to set it anyway - which won't work because there's no RAM vector table.

[kjbracey]

Oh, I see.

There's an issue here in that I was assuming that all targets with RAM vectors had NVIC_RAM_VECTOR_ADDRESS defined in their cmsis_nvic.h.

It appears that M0 devices like this one don't all have this define public - they sometimes have it internal.

It looks like the original code called NVIC_SetVector unconditionally. From which we can deduce that any targets with ROM vectors just ignore the call, or fault if it's set to something different than they have in ROM.

So I suggest changing this code to

NVIC_SetPriority(irq, 0xFF);
NVIC_SetVector(irq, (uint32_t)handler);
MBED_ASSERT(handler == (IRQHandler_t)NVIC_GetVector(irq));

Always attempt the set, and read it back to make sure it worked.

[maciejbocianski]

Exactly the old code called it unconditionally:

mbed-os/rtos/TARGET_CORTEX/SysTimer.cpp

Lines 82 to 94 in 1bf6b20

	void SysTimer::setup_irq()
	{
	#if (defined(NO_SYSTICK) && !defined (TARGET_CORTEX_A))
	NVIC_SetVector(mbed_get_m0_tick_irqn(), (uint32_t)SysTick_Handler);
	NVIC_SetPriority(mbed_get_m0_tick_irqn(), 0xFF); /* RTOS requires lowest priority */
	NVIC_EnableIRQ(mbed_get_m0_tick_irqn());
	#else
	// Ensure SysTick has the correct priority as it is still used
	// to trigger software interrupts on each tick. The period does
	// not matter since it will never start counting.
	OS_Tick_Setup(osRtxConfig.tick_freq, OS_TICK_HANDLER);
	#endif
	}

[maciejbocianski]

@kjbracey-arm updated

[jamesbeyond]

This PR fix the regression #11426, so I marked this as 5.14 rc3, @0xc0170

[mbed-ci]

Test run: FAILED

Summary: 1 of 4 test jobs failed
Build number : 1
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_build-GCC_ARM

[maciejbocianski]

Looks not related.
Strange errors while example compilation:

#### STDERR ####
[mbed] WARNING: Missing Python modules were not auto-installed.
       The Mbed OS tools in this program require the following Python modules: hidapi, pywin32, wmi
       You can install all missing modules by running "pip install -r requirements.txt" in "/builds/ws/mbed-os-ci_build-IAR/examples/mbed-os-example-ble-HeartRate/mbed-os"
       On Posix systems (Linux, etc) you might have to switch to superuser account or use "sudo"
---
[mbed] ERROR: "/usr/bin/python" returned error.
       Code: -11
       Path: "/builds/ws/mbed-os-ci_build-IAR/examples/mbed-os-example-ble-HeartRate"
       Command: "/usr/bin/python -u /builds/ws/mbed-os-ci_build-IAR/examples/mbed-os-example-ble-HeartRate/mbed-os/tools/make.py -t IAR -m NRF52_DK --source . --build ./BUILD/NRF52_DK/IAR"
       Tip: You could retry the last command with "-v" flag for verbose output

Compiling [mbed-os-example-blinky] for [CY8CPROTO_064_SB] with toolchain [GCC_ARM]

>  mbed-cli compile -t GCC_ARM -m CY8CPROTO_064_SB

#### STDOUT ####
[mbed] Working path "/builds/ws/mbed-os-ci_build-GCC_ARM@2/examples/mbed-os-example-blinky" (program)

#### STDERR ####
[mbed] WARNING: Could not find mbed program in current path "/builds/ws/mbed-os-ci_build-GCC_ARM@2/examples/mbed-os-example-blinky".
       You can fix this by calling "mbed new ." in the root of your program.
---
[mbed] ERROR: "/usr/bin/python" returned error.
       Code: -11
       Path: "/builds/ws/mbed-os-ci_build-GCC_ARM@2/examples/mbed-os-example-blinky"
       Command: "/usr/bin/python -m pip list -l"
       Tip: You could retry the last command with "-v" flag for verbose output
---

[0xc0170]

👍

CI restarted

[mbed-ci]

Test run: FAILED

Summary: 1 of 4 test jobs failed
Build number : 2
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_build-ARM

[0xc0170]

Ci restarted

[mbed-ci]

Test run: SUCCESS

Summary: 11 of 11 test jobs passed
Build number : 3
Build artifacts