Re: [PATCH v15 0/4] Adding the Sparx5 Serdes driver

[Steen Hegelund <steen.hegelund@microchip.com>]

Hi Kishon, Vinod, Andrew, Jacub, and David, 

I just wanted to know if you think that the Generic PHY subsystem might
not be the right place for this Ethernet SerDes PHY driver after all.

Originally I chose this subsystem for historic reasons: The
Microchip/Microsemi Ocelot SerDes driver was added here when it was
upstreamed.
On the other hand the Ocelot Serdes can do both PCIe and Ethernet, so
it might fit the signature of a generic PHY better.

At the moment the acceptance of the Sparx5 Serdes driver is blocking us
from adding the Sparx5 SwitchDev driver (to net), so it is really
important for us to resolve which subsystem the Serdes driver belongs
to.

I am very much looking forward to your response.

BR
Steen


On Thu, 2021-02-18 at 17:14 +0100, Steen Hegelund wrote:
> Adding the Sparx5 Serdes driver
> 
> This series of patches provides the serdes driver for the Microchip
> Sparx5
> ethernet switch.
> 
> The serdes driver supports the 10G and 25G serdes instances available
> in the
> Sparx5.
> 
> The Sparx5 serdes support several interface modes with several speeds
> and also
> allows the client to change the mode and the speed according to
> changing in the
> environment such as changing cables from DAC to fiber.
> 
> The serdes driver is to be used by the Sparx5 switchdev driver that
> will follow in subsequent series.
> 
> Sparx5 Architecture:
> ====================
> 
> Below is a diagram of the Ethernet transport part of the Sparx5 chip.
> 
> The diagram shows the switch core that sends/receives traffic via the
> Frame Bus
> and passes to the Port Modules.
> The Port Modules are able to talk to a SerDes via a Port Muxing
> configuration.
> The SerDes instances (33 in all) then passes the traffic on its lanes
> to the
> attached cuPHY or SFP module.
> 
>  +---------------------------------------------------------+
>  |                                                         |
>  |                         Switch Core                     |
>  |                                                         |
>  +----------------------------+----------------------------+
>                               |
>  -------+--------------+------+-------+--------------+-----+   Frame
> Bus
>         |              |              |              |
>  +------+-----+ +------+-----+ +------+-----+ +------+-----+
>  |1G/2.G Port | |5G Port     | |10G Port    | |25GG Port   |
>  |Modules     | |Modules     | |Modules     | |Modules     |
>  |MAC, PCS    | |MAC, PCS    | |MAC, PCS    | |MAC, PCS    |
>  +------+-----+ +------+-----+ +------+-----+ +------+-----+
>         |              |              |              |
>  -------+-+------------+-------+------+----------+---+-----+  Port
> Muxing
>           |                    |                 |
>     +-----+----+         +-----+----+         +--+-------+
>     |SerDes 5G |         |SerDes 10G|         |SerDes 25G|    SerDes
> Driver
>     |Lane (13) |         |Lane (12) |         |Lane (8)  |    Controls
> these
>     +-----+----+         +-----+----+         +-----+----+
>           |                    |                    |
>        to cuPHY             to cuPHY             to cuPHY
>        or SFP               or SFP               or SFP
> 
> The 33 SerDes instances are handled internally by 2 SerDes macros
> types:
> 
> - A 10G SerDes macro that supports the following rates and modes:
>   - 100 Mbps:
>        - 100BASE-FX
>   - 1.25 Gbps:
>        - SGMII
>        - 1000BASE-X
>        - 1000BASE-KX
>   - 3.125 Gbps:
>        - 2.5GBASE-X
>        - 2.5GBASE-KX
>   - 5 Gbps:
>        - QSGMII
>        - USGMII
>   - 5.15625 Gbps:
>        - 5GBASE-KR
>        - 5G-USXGMII
>   - 10 Gbps:
>        - 10G-USGMII
>   - 10.3125 Gbps:
>        - 10GBASE-R
>        - 10GBASE-KR
>        - USXGMII
> 
> - A 25G SerDes macro that supports the following rates and modes:
>   - 1.25 Gbps:
>        - SGMII
>        - 1000BASE-X
>        - 1000BASE-KX
>   - 3.125 Gbps:
>        - 2.5GBASE-X
>        - 2.5GBASE-KX
>   - 5 Gbps:
>        - QSGMII
>        - USGMII
>   - 5.15625 Gbps:
>        - 5GBASE-KR
>        - 5G-USXGMII
>   - 10 Gbps:
>        - 10G-USGMII
>   - 10.3125 Gbps:
>        - 10GBASE-R
>        - 10GBASE-KR
>        - USXGMII
>   - 10.3125 Gbps:
>        - 10GBASE-R
>        - 10GBASE-KR
>        - USXGMII
>   - 25.78125 Gbps:
>        - 25GBASE-KR
>        - 25GBASE-CR
>        - 25GBASE-SR
>        - 25GBASE-LR
>        - 25GBASE-ER
> 
> The SerDes driver handles these SerDes instances and configures them
> based on
> the selected mode, speed and media type.
> 
> In the current version of the SerDes driver only a subset of the above
> modes
> are supported: the modes that can be tested on our current evaluation
> boards
> (PCB134 and PCB35).
> 
> The first 13 10G SerDes macros are limited to 6G, and this gives the
> SerDes
> instance architecture shown on the diagram above.
> 
> The Port Muxing allows a Port Module to use a specific SerDes instance,
> but not
> all combinations are allowed.
> This is functionality as well as the configuration of the Port Modules
> is
> handled by the SwitchDev Driver.
> 
> The Sparx5 Chip Register Model can be browsed at this location:
> https://github.com/microchip-ung/sparx-5_reginfo
> and the datasheet is available here:
> https://ww1.microchip.com/downloads/en/DeviceDoc/SparX-5_Family_L2L3_Enterprise_10G_Ethernet_Switches_Datasheet_00003822B.pdf
> 
> History:
> --------
> v14 -> v15:
>     Changed the default interface function return value to -ENODEV.
>     Moved the CMU initialization, so that it is always done before the
>     serdes instance configuration.
>     Added a reference to the Sparx5 datasheet.
> 
> v13 -> v14:
>     Changed the 25g apply, 10g apply and the CMU configuration
> functions to
>     use a table based register update structure.
>     The table entries still need serdes indices/instances so the table
> must
>     be generated per serdes.
> 
> v12 -> v13:
>     Interface changes:
>         - Added set_media and set_speed interfaces on the generic phy
>         - Removed the ethernet SerDes configuration structure and its
>           header file.
>     Implementation changes:
>         - Implemented the new media and speed interfaces in the Serdes
> driver
>         - Removed the configure interface function in the SerDes driver
>         - The existing configuration function is now only used
> internally
> 
> v11 -> v12:
>     Used bitfields for bools in configuration structures.
>     Removed vertical alignment in structures.
>     Removed CONFIG_DEBUG_KERNEL guard around warning checks
> 
> v10 -> v11:
>     Rebased on v5.11-rc1
> 
> v9 -> v10:
>     Only add the new folder to the phy Kconfig (no sort fix)
>     Corrected the serdes mode conversion for 2.5G mode.
>     Clarified the SGMII and 1000BASEX conversion.
>     Improved some of the more cryptic error messages.
>     Expanded the validate function a bit, and removed the link status
>     from the return value.
> 
> v8 -> v9:
>     Replace pr_err with dev_err
>     Expanded the description here in the cover letter (should probably
> og into
>     the driver, at least part of it).
> 
> v7 -> v8:
>     Provide the IO targets as offsets from the start of the IO range
>     Initialise resource index
> 
> v6 -> v7:
>     This series changes the way the IO targets are provided to the
> driver.
>     Now only one IO range is available in the DT, and the driver has a
> table
>     to map its targets (as their order is still not sequential), thus
> reducing
>     the DT needed information and binding requirements.
>     The register access macros have been converted to functions.
> 
>     - Bindings:
>       - reg prop: minItems set to 1
>       - reg-names prop: removed
>     - Driver
>       - Use one IO range and map targets via this.
>       - Change register access macros to use functions.
>       - Provided a new header files with reg access functions.
>     - Device tree
>       - Provide only one IO range
> 
> v5 -> v6:
>      Series error: This had the same content as v5
> 
> v4 -> v5:
>     - Bindings:
>       - Removed .yaml from compatible string
>       - reg prop: removed description and added minItems
>       - reg-names prop: removed description and added const name list
> and
>         minItems
>       - #phy-cells prop: removed description and added maxItems
>     - Configuration interface
>       - Removed include of linux/phy.h
>       - Added include of linux/types.h
>     - Driver
>        - Added include of linux/phy.h
> 
> v3 -> v4:
>     - Add a reg-names item to the binding description
>     - Add a clocks item to the binding description
>     - Removed the clock parameter from the configuration interface
>     - Use the clock dt node to get the coreclock, and using that when
>       doing the actual serdes configuration
>     - Added a clocks entry with a system clock reference to the serdes
> node in
>       the device tree
> 
> v2 -> v3:
>     - Sorted the Kconfig sourced folders
>     - Sorted the Makefile included folders
>     - Changed the configuration interface documentation to use kernel
> style
> 
> v1 -> v2: Fixed kernel test robot warnings
>     - Made these structures static:
>       - media_presets_25g
>       - mode_presets_25g
>       - media_presets_10g
>       - mode_presets_10g
>     - Removed these duplicate initializations:
>       - sparx5_sd25g28_params.cfg_rx_reserve_15_8
>       - sparx5_sd25g28_params.cfg_pi_en
>       - sparx5_sd25g28_params.cfg_cdrck_en
>       - sparx5_sd10g28_params.cfg_cdrck_en
> 
> Steen Hegelund (4):
>   dt-bindings: phy: Add sparx5-serdes bindings
>   phy: Add media type and speed serdes configuration interfaces
>   phy: Add Sparx5 ethernet serdes PHY driver
>   arm64: dts: sparx5: Add Sparx5 serdes driver node
> 
>  .../bindings/phy/microchip,sparx5-serdes.yaml |  100 +
>  arch/arm64/boot/dts/microchip/sparx5.dtsi     |    8 +
>  drivers/phy/Kconfig                           |    1 +
>  drivers/phy/Makefile                          |    1 +
>  drivers/phy/microchip/Kconfig                 |   12 +
>  drivers/phy/microchip/Makefile                |    6 +
>  drivers/phy/microchip/sparx5_serdes.c         | 2480 +++++++++++++++
>  drivers/phy/microchip/sparx5_serdes.h         |  136 +
>  drivers/phy/microchip/sparx5_serdes_regs.h    | 2695 +++++++++++++++++
>  drivers/phy/phy-core.c                        |   30 +
>  include/linux/phy/phy.h                       |   26 +
>  11 files changed, 5495 insertions(+)
>  create mode 100644
> Documentation/devicetree/bindings/phy/microchip,sparx5-serdes.yaml
>  create mode 100644 drivers/phy/microchip/Kconfig
>  create mode 100644 drivers/phy/microchip/Makefile
>  create mode 100644 drivers/phy/microchip/sparx5_serdes.c
>  create mode 100644 drivers/phy/microchip/sparx5_serdes.h
>  create mode 100644 drivers/phy/microchip/sparx5_serdes_regs.h
> 
> --
> 2.30.0
>