hal/armv7a/imx6ull: add pctl for RTC config

[rmikielis]

SEN-92

Description

Since SNVS is in secure domain, only privileged software can change its state. Adding basic pctl
for secure RTC enabling/disabling was necessary

Tested and working, but please review if adding snvs registers to kernel page tables is done properly.

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: (sensorbox).

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).
• I will merge this PR by myself when appropriate.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces the necessary infrastructure to manage the Secure Non-Volatile Storage (SNVS) Real-Time Clock (RTC) on the i.MX6ULL platform. It enables privileged software to programmatically control the RTC's state, addressing the security requirement that SNVS components reside in a secure domain. The changes involve memory mapping, register definitions, and a new platform control interface for RTC operations.

Highlights

• SNVS Register Mapping: The _init.S file was updated to map the Secure Non-Volatile Storage (SNVS) registers into the kernel page tables, making them accessible for privileged operations.
• SNVS Register Definitions: New enum definitions for SNVS registers were added in imx6ull.c to provide symbolic names for register offsets, improving code readability and maintainability.
• RTC Control Function: A new static function, _imx6ull_setRTC, was implemented to enable or disable the Real-Time Clock (RTC) within the SNVS module, including a timeout mechanism for state changes.
• Platform Control Integration: The hal_platformctl function was extended to include a new pctl_snvs type, allowing privileged software to control the SNVS RTC state through the platform control interface.
• Platform Control Structure Update: The platformctl_t structure in imx6ull.h was modified to include the pctl_snvs type and a corresponding union member for passing RTC state values, enabling the new control functionality.

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[gemini-code-assist]

Code Review

The pull request introduces support for the i.MX6ULL's Secure Non-Volatile Storage (SNVS) and its Real-Time Clock (RTC). This involves mapping SNVS registers during system initialization, defining SNVS register offsets, adding SNVS register access to the platform's common structure, and implementing a function to control the RTC's enable/disable state. This RTC control is exposed through the hal_platformctl interface. A review comment notes that the newly introduced pctl_rtc_set_state enum in imx6ull.h is currently unused and should either be removed or refactored for better clarity.

[gemini-code-assist]

The new enum pctl_rtc_set_state is defined but not used anywhere in the codebase. It seems to add confusion without providing functionality. If the intention is to define constants for enabling/disabling the RTC, it would be better to define them explicitly (e.g., RTC_STATE_DISABLE = 0, RTC_STATE_ENABLE = 1). As it is, this enum should probably be removed to avoid confusion.

[github-actions]

Unit Test Results

9 553 tests  ±0   8 961 ✅ ±0   53m 14s ⏱️ +30s
  591 suites ±0     592 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit 0ad6410. ± Comparison against base commit cbfa5d0.