T-Head TH1520 RISC-V SoC clock controller
Clock controller support for the T-Head TH1520, a quad-core RISC-V system-on-chip used in developer boards and laptops such as Sipeed's Lichee Pi 4A and Lichee Book 4A. It manages the SoC's application-processor and video-output clock trees so Linux can bring up CPUs, scale frequencies, and gate peripherals.
recommendation
It should stay because the TH1520 is a current RISC-V chip with hardware still being sold in 2025 through Sipeed's Lichee Pi 4A board and Lichee Book 4A laptop, and the driver is under active development upstream. It first landed in mid-2024 and was still gaining new features such as CPU frequency scaling as of late 2025, with no equivalent replacement possible since clock control is SoC-specific.
repository signals
sources
- lwn.net
The driver was introduced upstream in June 2024 as support for the T-Head TH1520 AP_SUBSYS clock controller.
- spinics.net
As of November 20, 2025, new functionality for this driver was still being posted upstream, specifically CPU frequency scaling support for TH1520.
- wiki.sipeed.com
Sipeed documented a TH1520-based Lichee Book 4A product in 2024, indicating new TH1520-based systems remained an active product line near 2025.
- wiki.sipeed.com
Sipeed's Lichee Pi 4A page describes a TH1520-based Linux development board and explicitly mentions an online store, supporting evidence of retail availability.
codex reasoning notes (technical)
Real driver directory: platform clock-controller driver for TH1520 AP/VO clocks (`compatible` strings in local file inspection via shell). Upstream activity is recent and substantive: local `git log` (shell, safe.directory override) shows multiple functional commits in 2025-08, 2025-12, and 2026-01; web search with exact patch subjects found LWN for the initial 2024 submission and Spinics for the 2025 CPUfreq series. Targeted web searches did not surface any removal/deprecation discussion. Deployment looks niche rather than mass-market: TH1520 appears in Sipeed developer products/laptop docs obtained via web search, so new deployments still exist but are low-volume. No natural replacement driver exists because this is SoC-specific clock control for TH1520.