Loongson LS1x and LS2K on-chip APB DMA engines
The on-chip DMA controllers built into Loongson's LS1-series and LS2K-series MIPS/LoongArch system-on-chips, which Loongson sells today for industrial control, embedded terminals, and similar Chinese-market applications. The controllers shuttle data between the SoC and peripherals like NAND flash, audio, I2C, and USB without tying up the CPU.
recommendation
Worth keeping but documenting as niche platform support, because the hardware is genuinely current — Loongson still lists the LS2K1000LA, LS2K0500, and LS1 parts in its 2025 industrial catalog — and the dmaengine subsystem accepted fresh code for it in 2024, including a v12 LS1 series in August and a maintainer-applied LS2 fix in December. Volumes outside China are small and there is no other in-tree driver that could replace it, so the right posture is to retain it and flag it as low-deployment SoC support.
repository signals
sources
- spinics.net
Loongson-1 APB DMA support was actively upstreamed in August 2024 as a v12 patch series, indicating recent maintainer-reviewed enablement rather than abandonment.
- spinics.net
Loongson-2 APB DMA received an upstream fix that Vinod Koul applied in December 2024, showing real recent dmaengine maintainer attention.
- loongson.cn
Loongson still listed LS2K1000LA, LS2K0500 and multiple LS1-series parts in its industrial/embedded product catalog, consistent with ongoing new-sales availability in 2025.
- loongson.cn
LS2K1000LA is marketed for industrial control and terminal applications and exposes peripheral interfaces such as NAND, I2S, HDA, I2C, USB 2.0 and GMAC, matching an SoC class that uses an on-chip APB DMA engine.
codex reasoning notes (technical)
Local shell inspection showed the candidate maps to Loongson DMA drivers now stored as drivers/dma/loongson1-apb-dma.c and drivers/dma/loongson2-apb-dma.c, with local git log showing substantive 2024 addition/fix activity plus a 2024 loongson2 follow-up; this contradicts the stale phase-1 metadata. URLs were obtained by web search: spinics patch threads for upstream activity, and Loongson product/catalog pages for present-day deployment evidence. No removal discussion was found in the gathered evidence. Hardware appears current but niche industrial/embedded rather than mass-market, so keep the driver and annotate it as low-volume platform support with no natural in-tree replacement.