As U-Boot works to align itself with upstream devicetrees, there are some common issues we start to run into, that of hardware blocks which might be important for an OS like Linux, but which aren't useful in U-Boot.
For example, the Resource Power Manager found on Qualcomm platforms includes clock controllers and power domains which are only useful for managing power consumption and enabling low power states.
As this is not at all relevant for U-Boot, we can safely ignore these devices, but we don't have a good way to communicate that to U-Boot.
As an initial step, implement a "stub" clock driver which can be bound to these devices so that drivers will work as expected. Add the necessary compatibles for the rpmcc and rpmh-clk controllers on older rpm (non-h) platforms and the sm8250/8550/8650 platforms.
To: Tom Rini trini@konsulko.com To: Lukasz Majewski lukma@denx.de To: Sean Anderson seanga2@gmail.com To: Caleb Connolly caleb.connolly@linaro.org To: Neil Armstrong neil.armstrong@linaro.org To: Sumit Garg sumit.garg@linaro.org Cc: Heinrich Schuchardt xypron.glpk@gmx.de Cc: Ilias Apalodimas ilias.apalodimas@linaro.org Cc: u-boot@lists.denx.de Cc: u-boot-qcom@groups.io
Changes in v3: - Add 8250/855/8650 rpmh clk stubs - Link to v2: https://lore.kernel.org/r/20240527-b4-clk-stub-v2-0-29013855e343@linaro.org
Changes in v2: - Take the other discussed approach of just implementing a stub driver. - Link to v1: https://lore.kernel.org/r/20240410-b4-stub-drivers-v1-0-6935bd2c07d1@linaro....
--- Caleb Connolly (2): clk: add stub clock driver qcom_defconfig: enable stub clock
configs/qcom_defconfig | 1 + drivers/clk/Kconfig | 7 ++++++ drivers/clk/Makefile | 1 + drivers/clk/clk-stub.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 75 insertions(+) --- base-commit: d0f74bd417daf6492975ce346843ba0767caf51c
// Caleb (they/them)