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The NXP S32G2 and S32G3 platforms integrate a successive approximation register (SAR) ADC. Two instances are available, each providing 8 multiplexed input channels with 12-bit resolution. The conversion rate is up to 1 Msps depending on the configuration and sampling window. The SAR ADC supports raw, buffer, and trigger modes. It can operate in both single-shot and continuous conversion modes, with optional hardware triggering through the cross-trigger unit (CTU) or external events. An internal prescaler allows adjusting the sampling clock, while per-channel programmable sampling times provide fine-grained trade-offs between accuracy and latency. Automatic calibration is performed at probe time to minimize offset and gain errors. All modes have been validated on the S32G274-RDB2 platform using an externally generated square wave captured by the ADC. Tests covered buffered streaming via IIO, trigger synchronization, and accuracy verification against a precision laboratory signal source. One potential scenario, not detected during testing, is that in some corner cases the DMA may already have been armed for the next transfer, which can lead dmaengine_tx_status() to return an incorrect residue. The callback_result() operation—intended to supply the residue directly and eliminate the need to call dmaengine_tx_status()—also does not work. Attempting to use dmaengine_pause() and dmaengine_resume() to prevent the residue from being updated does not work either. This potential scenario should apply to any driver using cyclic DMA. However, no current driver actually handles this case, and they all rely on the same acquisition routine (e.g., the STM32 implementation). The NXP SAR acquisition routine has been used in production for several years, which is a good indication of its robustness. As the IIO is implementing the cyclic DMA support API, it is not worth to do more spins to the current routine as it will go away when the new API will be available. The driver is derived from the BSP implementation and has been partly rewritten to comply with upstream requirements. For this reason, all contributors to the original code are listed as co-developers. Originally-by: Stefan-Gabriel Mirea <stefan-gabriel.mirea@nxp.com> Co-developed-by: Alexandru-Catalin Ionita <alexandru-catalin.ionita@nxp.com> Signed-off-by: Alexandru-Catalin Ionita <alexandru-catalin.ionita@nxp.com> Co-developed-by: Ciprian Costea <ciprianmarian.costea@nxp.com> Signed-off-by: Ciprian Costea <ciprianmarian.costea@nxp.com> Co-developed-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@oss.nxp.com> Signed-off-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@oss.nxp.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst