usb: Adapt USB stack to work on ia32

[adamgreloch]

JIRA: RTOS-937

Description

Motivation and Context

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (refactoring, style fixes, git/CI config, submodule management, no code logic changes)

How Has This Been Tested?

• Already covered by automatic testing.
• New test added: (add PR link here).
• Tested by hand on: (list targets here).

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing linter checks and tests passed.
• My changes generate no new compilation warnings for any of the targets.

Special treatment

• This PR needs additional PRs to work (list the PRs, preferably in merge-order).
  Adapt USB stack to work on ia32 phoenix-rtos-usb#34
  hal/ia32: Add platformctls for ehci phoenix-rtos-kernel#625
• I will merge this PR by myself when appropriate.

[agkaminski]

General remark - might be nice to separate platform dependent parts in a per arch files (ehci-ia32-generic.c etc?)

[agkaminski]

https://godbolt.org/z/1q4s7Gsbe

Suggested change

	#ifdef EHCI_IMX
	asm volatile("dmb" ::: "memory");
	#else
	__sync_synchronize();
	#endif
	__sync_synchronize();

[adamgreloch]

GCC won't reduce __sync_synchronize() to dmb prior to 9.3.1, see e.g. 9.2.1 https://godbolt.org/z/orPnWevvn

[adamgreloch]

General remark - might be nice to separate platform dependent parts in a per arch files (ehci-ia32-generic.c etc?)

I agree and intend on doing it once I get the EHCI to work on the hardware, since for now it's uncertain which parts of the driver will end up being common. The proposed changes work on QEMU, but as it turned out during my recent tests on hardware (which weren't possible before, because I had to find the controllers' IRQs via ACPI interpretation first), EHCI emulation in QEMU was extremely permissive. I am therefore moving this PR back to draft until I fix the hardware