Re: [PATCH v3 0/9] mips: ralink: add complete clock and reset driver for mtmips SoCs

[Sergio Paracuellos <sergio.paracuellos@gmail.com>]

On Tue, Apr 18, 2023 at 11:03 AM Sergio Paracuellos
<sergio.paracuellos@gmail.com> wrote:
>
> Hi all!
>
> This patchset is a big effort to properly implement a clock and reset
> driver for old ralink SoCs. This allow to properly define clocks in
> device tree and avoid to use fixed-clocks directly from 'arch/mips/ralink'
> architecture directory code.
>
> Device tree 'sysc' node will be both clock and reset provider using
> 'clock-cells' and 'reset-cells' properties.
>
> The ralink SoCs we are taking about are RT2880, RT3050, RT3052, RT3350,
> RT3352, RT3883, RT5350, MT7620, MT7628 and MT7688. Mostly the code in
> this new driver has been extracted from 'arch/mips/ralink' and cleanly
> put using kernel clock and reset driver APIs. The clock plans for this
> SoCs only talks about relation between CPU frequency and BUS frequency.
> This relation is different depending on the particular SoC. CPU clock is
> derived from XTAL frequencies.
>
>  Depending on the SoC we have the following frequencies:
>  * RT2880 SoC:
>      - XTAL: 40 MHz.
>      - CPU: 250, 266, 280 or 300 MHz.
>      - BUS: CPU / 2 MHz.
>   * RT3050, RT3052, RT3350:
>      - XTAL: 40 MHz.
>      - CPU: 320 or 384 MHz.
>      - BUS: CPU / 3 MHz.
>   * RT3352:
>      - XTAL: 40 MHz.
>      - CPU: 384 or 400 MHz.
>      - BUS: CPU / 3 MHz.
>      - PERIPH: 40 MHz.
>   * RT3383:
>      - XTAL: 40 MHz.
>      - CPU: 250, 384, 480 or 500 MHz.
>      - BUS: Depends on RAM Type and CPU:
>        + RAM DDR2: 125. ELSE 83 MHz.
>        + RAM DDR2: 128. ELSE 96 MHz.
>        + RAM DDR2: 160. ELSE 120 MHz.
>        + RAM DDR2: 166. ELSE 125 MHz.
>   * RT5350:
>       - XTAL: 40 MHz.
>       - CPU: 300, 320 or 360 MHz.
>       - BUS: CPU / 3, CPU / 4, CPU / 3 MHz.
>       - PERIPH: 40 MHz.
>   * MT7628 and MT7688:
>      - XTAL: 20 MHz or 40 MHz.
>      - CPU: 575 or 580 MHz.
>      - BUS: CPU / 3.
>      - PCMI2S: 480 MHz.
>      - PERIPH: 40 MHz.
>   * MT7620:
>      - XTAL: 20 MHz or 40 MHz.
>      - PLL: XTAL, 480, 600 MHz.
>      - CPU: depends on PLL and some mult and dividers.
>      - BUS: depends on PLL and some mult and dividers.
>      - PERIPH: 40 or XTAL MHz.
>
> MT7620 is a bit more complex deriving CPU clock from a PLL and an bunch of
> register reads and predividers. To derive CPU and BUS frequencies in the
> MT7620 SoC 'mt7620_calc_rate()' helper is used.
> In the case XTAL can have different frequencies and we need a different
> clock frequency for peripherals 'periph' clock in introduced.
> The rest of the peripherals present in the SoC just follow their parent
> frequencies.
>
> I am using 'mtmips' inside for ralink clock driver. This is aligned with
> pinctrl series recently merged through pinctrl git tree [0].
>
> I am maintaining ralink as prefix for compatible strings after discussions
> between Rob and Arinc in v2 of this series [1].
>
> Changes have been compile tested for:
> - RT2880
> - RT3883
> - MT7620
>
> Changes have been properly tested in RT5350 SoC based board (ALL5003 board)
> resulting in a working platform.
>
> Dts files for these SoCs in-tree except MT7621 are incomplete. We are
> planning to align with openWRT files at some point and add extra needed
> changes. Hence I am not touching them at all in these series. If this is
> a problem, please let me know and I will update them.
>
> Talking about merging this series I'd like all of the patches going through
> the MIPS tree if possible.
>
> Thanks in advance for your time.
>
> Best regards,
>     Sergio Paracuellos
>
> Changes in v3:
> - Address Stephen comments in v2:
>     + Drop unsused include '<linux/clk.h>'.
>     + Add fixed and factor clocks when it makes sense.
>     + Make 'mtmips_periph_clk_ops' named variable.
>     + WARN_ON -> WARN_ON_ONCE.
>     + Avoid CONFIG_USB dependent code. Introduce new 'mtmips_clk_regs_init'.
>     + Don't validate the bindings in the driver.
>     + Make const 'struct clk_init_data' used inside macros.
>     + do_div -> div_u64.
>     + Make use of dev_err_probe.

Hi Stephen,

Does anything else need to be addressed to have all of these added?

Philipp, can you please review the reset related code in PATCH 2/9 of
these series?

Thanks in advance for your time!

Best regards,
    Sergio Paracuellos

>
> Changes in v2:
> - Address bindings documentation changes pointed out by Krzysztof:
>     + Rename the file into 'mediatek,mtmips-sysc.yaml'.
>     + Redo commit subject and log message.
>     + Order compatibles alphabetically.
>     + Redo bindings description taking into account this is a system
>       controller node which provides both clocks and resets to the world.
>     + Drop label from example.
>     + Use 'syscon' as node name in example.
>     + Drop no sense 'ralink,rt2880-reset' compatible string
> - Squash patches 6 and 7 together as pointed out by Stephen Boyd.
>
> Previoous series:
> v2: https://lore.kernel.org/linux-clk/CAMhs-H-BfZb3mD8E=LeJ4vT22uibQ1DnaZsfTrtRxSiv=8L5RA@mail.gmail.com/T/#t
> v1: https://lore.kernel.org/linux-clk/20230320161823.1424278-1-sergio.paracuellos@gmail.com/T/#t
>
> [0]: https://lore.kernel.org/linux-gpio/e9e6ad87-2db5-9767-ff39-64a302b06185@arinc9.com/T/#t
> [1]: https://lore.kernel.org/linux-clk/CAMhs-H-BfZb3mD8E=LeJ4vT22uibQ1DnaZsfTrtRxSiv=8L5RA@mail.gmail.com/T/#mfe725b6e3382c6fb09736472a846cbbc84f264dc
>
> Sergio Paracuellos (9):
>   dt-bindings: clock: add mtmips SoCs system controller
>   clk: ralink: add clock and reset driver for MTMIPS SoCs
>   mips: ralink: rt288x: remove clock related code
>   mips: ralink: rt305x: remove clock related code
>   mips: ralink: rt3883: remove clock related code
>   mips: ralink: mt7620: remove clock related code
>   mips: ralink: remove reset related code
>   mips: ralink: get cpu rate from new driver code
>   MAINTAINERS: add Mediatek MTMIPS Clock maintainer
>
>  .../bindings/clock/mediatek,mtmips-sysc.yaml  |   65 +
>  MAINTAINERS                                   |    6 +
>  arch/mips/include/asm/mach-ralink/mt7620.h    |   35 -
>  arch/mips/include/asm/mach-ralink/rt288x.h    |   10 -
>  arch/mips/include/asm/mach-ralink/rt305x.h    |   21 -
>  arch/mips/include/asm/mach-ralink/rt3883.h    |    8 -
>  arch/mips/ralink/clk.c                        |   26 +-
>  arch/mips/ralink/common.h                     |    5 -
>  arch/mips/ralink/mt7620.c                     |  226 ----
>  arch/mips/ralink/of.c                         |    4 -
>  arch/mips/ralink/reset.c                      |   61 -
>  arch/mips/ralink/rt288x.c                     |   31 -
>  arch/mips/ralink/rt305x.c                     |   78 --
>  arch/mips/ralink/rt3883.c                     |   44 -
>  drivers/clk/ralink/Kconfig                    |    7 +
>  drivers/clk/ralink/Makefile                   |    1 +
>  drivers/clk/ralink/clk-mtmips.c               | 1134 +++++++++++++++++
>  17 files changed, 1232 insertions(+), 530 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/clock/mediatek,mtmips-sysc.yaml
>  create mode 100644 drivers/clk/ralink/clk-mtmips.c
>
> --
> 2.25.1
>