drivers/sh/clk · keep-annotate

Legacy SuperH clock framework (CPG)

An older clock and clock-pulse-generator framework used by Renesas SuperH (SH-3, SH-4, SH-4A, and early SH-Mobile) processors. It manages on-chip clocks for SoCs that powered set-top boxes, printers, automotive infotainment, and embedded gear from roughly the early 2000s through the mid-2010s, before Renesas largely shifted these product lines to Arm-based successors.

keep-annotate conf=0.78 last_sold=2015 deploy=low replacement=drivers/clk/renesas (Common Clock Framework) subsystem=sh category=infrastructure

78%

recommendation

Worth keeping but worth flagging as legacy because several arch/sh board files still depend on it, so removing it would break support for existing SuperH systems. The framework predates the modern Common Clock Framework used by drivers/clk/renesas, and upstream activity has dwindled to occasional bug fixes (such as a 2023 patch from Geert Uytterhoeven). Renesas has marked much of the SH-4/SH-4A ecosystem as discontinued or not recommended for new designs, with longevity sales running through about March 2025, so new deployments are rare and the code mostly serves to keep older boards booting.

repository signals

3 files

1,108 source lines

5 commits, 5y

+24 / −17 lines added / removed, 5y

5 authors, 5y

monthly commits · 2021-04-21 → 2026-04-21 · 5 total · active in 4/61 months

sources

lore.kernel.org
Public lore thread for a real SH clock bug fix in 2023, showing some upstream maintenance rather than complete abandonment.
git.kernel.org
The in-tree API is explicitly labeled with legacy SH clock/CPG interfaces such as CONFIG_SH_CLK_CPG_LEGACY, indicating this is an older framework.
en.wikipedia.org
SuperH SH-3/SH-4/SH-4A based SoCs were later replaced by Arm-based generations, while many existing models reportedly remained marketed only through March 2025 under Renesas longevity programs.
renesas.com
Renesas marks a SuperH SH-4/SH-4A ecosystem product as discontinued and says listed target devices are obsolete or not recommended for new designs, supporting legacy-only market status.

codex reasoning notes (technical)

Obtained local evidence with shell: inspected drivers/sh/clk/{core,cpg}.c and include/linux/sh_clk.h, then used local git log and rg. Local tree shows this code is a legacy SH clock framework still referenced by multiple arch/sh clock files, so it cannot be removed blindly. Local git history showed only sparse recent touches, with one substantive 2023 bug-fix whose lore URL came from `git log`; no removal-thread evidence surfaced in the inspected history. The kernel.org include/linux/sh_clk.h URL is canonical recall to anchor the legacy-framework claim. Wikipedia and the Renesas discontinued SH-4 tool page were obtained via web search and support the market conclusion: SH-3/4-era hardware is largely legacy, with at most tail-end 2025 availability and low current deployments. That combination supports keep-annotate rather than deprecate/remove.