SiFive FU540 Platform DMA Engine
The on-chip platform DMA engine inside SiFive's Freedom U540 (FU540-C000) RISC-V SoC, best known as the processor in the 2018 HiFive Unleashed development board. It moves data between memory and peripherals on early RISC-V Linux-capable hardware used for kernel and toolchain bring-up.
recommendation
Worth keeping but documenting its niche because the FU540 SoC powers the long-discontinued HiFive Unleashed board and a handful of derivative designs rather than any currently shipping hardware. Even so, the driver continues to receive real bug-fix patches into 2024 and beyond, suggesting a small but active community of RISC-V developers still relies on it for bring-up and legacy boards.
repository signals
sources
- static.dev.sifive.com
Vendor manual named in the driver source documents the FU540-C000 Platform DMA Engine targeted by this driver.
- lore.kernel.org
As of 2026-02-20 the driver was still receiving nontrivial bug-fix patches upstream, indicating active maintenance rather than abandonment.
- lore.kernel.org
The driver also saw targeted correctness fixes in late 2024, reinforcing that real users still exercise it.
- sifive.com
SiFive's current board page marks HiFive Unleashed as Discontinued and identifies it as using the Freedom U540 (FU540) SoC; the page places it under Legacy Boards rather than Available Now.
codex reasoning notes (technical)
Driver source inspection via functions.exec_command shows this is the SiFive FU540 Platform DMA driver. lore_file_timeline on drivers/dma/sf-pdma/sf-pdma.c showed recent 2024-2026 fix traffic and no visible removal/deprecation series in the returned recent subjects, so removal is not indicated. Web search + open on sifive.com showed the main FU540 board (HiFive Unleashed) is discontinued/legacy, so new-hardware sales in 2025 look unlikely. Conclusion: niche legacy/bring-up deployments likely remain, but hardware is not current; keep the driver, annotate it as legacy-oriented rather than deprecating or removing it.