Intel Medfield and Merrifield High-Speed UART DMA controller
Handles direct memory access for the high-speed UART blocks built into Intel's Medfield and Merrifield Atom systems-on-chip, the smartphone-oriented x86 platforms found in early-2010s devices like the Motorola RAZR i and Atom Z3480 phones. It is a SoC-specific helper block, not a general-purpose DMA engine, and is bound to just two Intel PCI IDs.
recommendation
Worth keeping but documenting its niche, because the only hardware that uses it was Intel's short-lived Medfield and Merrifield phone chips (Q1 2014, now discontinued and end-of-servicing). Despite the obscure user base, the code is still being touched upstream — including 2026 maintenance and API-modernisation patches — so there is no current push to remove it, and there is no generic successor driver since the UART DMA block is SoC-specific.
repository signals
sources
- lore.kernel.org
The driver still received upstream maintenance in 2026 (`dmaengine: hsu: use kzalloc_flex()`), so it is not abandoned in-tree.
- lore.kernel.org
The PCI side also saw a 2026 API-conversion patch (`Replace pci_alloc_irq_vectors() with pcim_alloc_irq_vectors()`), indicating continued compile/runtime upkeep rather than removal.
- cateee.net
LKDDb ties this driver to only two Intel PCI IDs: 8086:081e (Medfield Serial IO HSUART DMA Controller) and 8086:1192 (Merrifield Serial IO HSUART DMA Controller).
- intel.com
Intel's Merrifield Atom Z3480 product page marks the platform as Q1'14, mobile, discontinued, end-of-servicing, and not offered as an embedded option.
- en.wikipedia.org
Medfield appeared in early-2010s smartphones such as the Motorola RAZR i, which was announced in September 2012.
codex reasoning notes (technical)
Real driver: `drivers/dma/hsu` contains DMA engine core plus PCI probe code for Intel HSUART DMA. Lore evidence came from `lore_file_timeline` on `drivers/dma/hsu/hsu.c` and `drivers/dma/hsu/pci.c`; both showed 2026 maintenance patches and no visible removal signal in the sampled history, so I backed off from deprecate to keep-annotate despite old hardware. Deployment evidence came from web search results: LKDDb identified only Medfield/Merrifield PCI IDs; Intel's product page showed Merrifield mobile parts are discontinued/end-of-servicing; Wikipedia results placed Medfield devices in 2012-era phones. That points to legacy/collector/industrial leftovers only, with low present-day deployments and no obvious generic replacement driver because this is a SoC-specific UART DMA block rather than a swappable DMA-controller class successor.