[PATCH v6 0/6] clk: Support spread spectrum and use it in clk-scmi

[Peng Fan]

Hi All,

Sorry for top-posting. There is only one comment from Krzysztof regarding
cleanup API usage. Since 6.19 rc1 still not out, I will wait two more weeks
to collect comments, then post v7. Hopefully, you are ok with current
clk-scmi-oem stuff.

Thanks,
Peng.

On Fri, Nov 28, 2025 at 11:14:09AM +0800, Peng Fan (OSS) wrote:
>Since the assigned-clock-sscs property [1] has been accepted into the device
>tree schema, we can now support it in the Linux clock driver. Therefore,
>I've picked up the previously submitted work [2] titled "clk: Support
>spread spectrum and use it in clk-pll144x and clk-scmi."
>As more than six months have passed since [2] was posted, I’m treating this
>patchset as a new submission rather than a v3.
>
>- Introduce clk_set_spread_spectrum to set the parameters for enabling
>  spread spectrum of a clock.
>- Parse 'assigned-clock-sscs' and configure it by default before using the
>  clock. This property is parsed before parsing clock rate.
>- Enable this feature for clk-scmi on i.MX95.
>
>Because SCMI spec will not include spread spectrum as a standard
>extension, we still need to use NXP i.MX OEM extension.
>
>[1] https://github.com/devicetree-org/dt-schema/pull/154
>[2] https://lore.kernel.org/all/20250205-clk-ssc-v2-0-fa73083caa92@nxp.com/
>
>Signed-off-by: Peng Fan <peng.fan at nxp.com>
>---
>Changes in v6:
>- Add kunit build warning
>- Update OEM string comparation per Sebin
>
>Changes in v5:
>- Per Stephen, export clk_hw_set_spread_spectrum, use enum for method,
>  add const for set_spread_spectrum and rename clk_ss/conf to ss_conf.
>- Per Sebin, Cristian, Sudeep, I added clk-scmi-oem.c to support vendor
>  extensions.
>- Link to v4: https://lore.kernel.org/arm-scmi/aNQPWO6pfA_3mmxf@redhat.com/T/#me81231bf286e2a8e4e00a68707ed1e525a2b4a3d
>
>Changes in v4:
>- Add R-b for patch 1 from Brian
>- Drop unecessary change in patch 4 Per Brian
>- Link to v3: https://lore.kernel.org/r/20250912-clk-ssc-version1-v3-0-fd1e07476ba1@nxp.com
>
>Changes in v3:
>- New patch 1 for dt-bindings per comment from Brian
>  https://lore.kernel.org/all/aLeEFzXkPog_dt2B@x1/
>  This might not be good to add a new dt-binding file in v3. But this is
>  quite a simple file that just has four macros to encode modulation
>  method. So hope this is fine for DT maintainers.
>- Add Brain's R-b for patch 2
>- New patch 3 to add Kunit test per Brain. Since Brain helped
>  draft part of the code, I added Co-developed-by tag from Brain.
>- Link to v2: https://lore.kernel.org/r/20250901-clk-ssc-version1-v2-0-1d0a486dffe6@nxp.com
>
>Changes in v2:
>- Simplify the code in patch 2 per Dan Carpenter and Brian Masney
>- Rebased to next-20250829
>- Link to v1: https://lore.kernel.org/r/20250812-clk-ssc-version1-v1-0-cef60f20d770@nxp.com
>
>---
>Peng Fan (6):
>      dt-bindings: clock: Add spread spectrum definition
>      clk: Introduce clk_hw_set_spread_spectrum
>      clk: conf: Support assigned-clock-sscs
>      clk: Add KUnit tests for assigned-clock-sscs
>      clk: scmi: Introduce common header for SCMI clock interface
>      clk: scmi: Add i.MX95 OEM extension support for SCMI clock driver
>
> drivers/clk/Makefile                               |   8 +-
> drivers/clk/clk-conf.c                             |  69 ++++++++++++
> drivers/clk/clk-scmi-oem.c                         | 103 ++++++++++++++++++
> drivers/clk/clk-scmi.c                             |  44 +++-----
> drivers/clk/clk-scmi.h                             |  51 +++++++++
> drivers/clk/clk.c                                  |  27 +++++
> drivers/clk/clk_test.c                             | 121 ++++++++++++++++++++-
> drivers/clk/kunit_clk_assigned_rates.h             |  10 ++
> drivers/clk/kunit_clk_assigned_rates_multiple.dtso |   6 +
> ...kunit_clk_assigned_rates_multiple_consumer.dtso |   6 +
> drivers/clk/kunit_clk_assigned_rates_one.dtso      |   3 +
> .../clk/kunit_clk_assigned_rates_one_consumer.dtso |   3 +
> .../clk/kunit_clk_assigned_rates_u64_multiple.dtso |   6 +
> ...t_clk_assigned_rates_u64_multiple_consumer.dtso |   6 +
> drivers/clk/kunit_clk_assigned_rates_u64_one.dtso  |   3 +
> .../kunit_clk_assigned_rates_u64_one_consumer.dtso |   3 +
> drivers/clk/kunit_clk_assigned_sscs_null.dtso      |  16 +++
> .../clk/kunit_clk_assigned_sscs_null_consumer.dtso |  20 ++++
> drivers/clk/kunit_clk_assigned_sscs_without.dtso   |  15 +++
> .../kunit_clk_assigned_sscs_without_consumer.dtso  |  19 ++++
> drivers/clk/kunit_clk_assigned_sscs_zero.dtso      |  12 ++
> .../clk/kunit_clk_assigned_sscs_zero_consumer.dtso |  16 +++
> include/dt-bindings/clock/clock.h                  |  14 +++
> include/linux/clk-provider.h                       |  31 ++++++
> 24 files changed, 580 insertions(+), 32 deletions(-)
>---
>base-commit: ef68bf704646690aba5e81c2f7be8d6ef13d7ad8
>change-id: 20251127-clk-ssc-v6-2-57658f944324
>
>Best regards,
>-- 
>Peng Fan <peng.fan at nxp.com>
>