Eckelmann SIOX industrial control bus
SIOX is a proprietary fieldbus designed by the German company Eckelmann for daisy-chaining sensor and actuator modules in supermarket refrigeration and building-management installations. The kernel ships a bus core plus a GPIO-bitbang master, letting a Linux controller talk to Eckelmann's expansion modules over a few general-purpose I/O lines.
recommendation
Worth keeping but documenting as niche, because deployment is narrow (Eckelmann refrigeration and building-automation gear) yet the hardware is still sold new in 2025 and the code is genuinely maintained, with cleanup patches landing on the GPIO master in 2024 and core updates as recent as 2026. There is no other Linux driver that speaks this bus, so removing it would strand the customers who use it; an in-tree note clarifying the special-purpose nature would help future maintainers triage it correctly.
repository signals
sources
- lore.kernel.org
The core driver still receives upstream maintenance in 2026 ('siox: use kzalloc_flex').
- lore.kernel.org
The GPIO bus side saw substantive cleanup work in 2024, indicating active stewardship rather than abandonment.
- eckelmann.de
Eckelmann still markets 'SIOX Series' expansion modules for refrigeration/building-management systems, so the hardware family remained commercially offered in 2025.
- cateee.net
LKDDb shows CONFIG_SIOX and CONFIG_SIOX_BUS_GPIO remain present in current kernel series and identifies the supported platform/OF binding.
codex reasoning notes (technical)
Real driver, not an early-exit case. Local shell inspection (`rg`, `sed`) showed a bus core plus GPIO master driver and Kconfig describes a niche Eckelmann refrigeration/control bus. MCP `lore_file_timeline` on `drivers/siox/siox-core.c` and `drivers/siox/siox-bus-gpio.c` showed recent non-removal traffic through 2025-2026, so this is not dead code. Web `search_query` found Eckelmann product pages still listing SIOX expansion modules and LKDDb coverage pages. Net: niche industrial deployment remains low but extant; no natural replacement driver for the same bus, so keep upstream but annotate as niche/special-purpose rather than deprecate/remove.