Re: [net-next PATCH v6 06/10] net: pcs: Add Xilinx PCS driver

[Sean Anderson <sean.anderson@linux.dev>]

On 6/11/25 01:11, Maxime Chevallier wrote:
> Hi Sean,
> 
> I only 
> 
> On Tue, 10 Jun 2025 19:31:30 -0400
> Sean Anderson <sean.anderson@linux.dev> wrote:
> 
>> This adds support for the Xilinx 1G/2.5G Ethernet PCS/PMA or SGMII device.
>> This is a soft device which converts between GMII and either SGMII,
>> 1000Base-X, or 2500Base-X. If configured correctly, it can also switch
>> between SGMII and 1000BASE-X at runtime. Thoretically this is also possible
>> for 2500Base-X, but that requires reconfiguring the serdes. The exact
>> capabilities depend on synthesis parameters, so they are read from the
>> devicetree.
>> 
>> This device has a c22-compliant PHY interface, so for the most part we can
>> just use the phylink helpers. This device supports an interrupt which is
>> triggered on autonegotiation completion. I'm not sure how useful this is,
>> since we can never detect a link down (in the PCS).
>> 
>> This device supports sharing some logic between different implementations
>> of the device. In this case, one device contains the "shared logic" and the
>> clocks are connected to other devices. To coordinate this, one device
>> registers a clock that the other devices can request.  The clock is enabled
>> in the probe function by releasing the device from reset. There are no othe
>> software controls, so the clock ops are empty.
>> 
>> Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
>> ---
>> 
>> Changes in v6:
>> - Move axienet_pcs_fixup to AXI Ethernet commit
>> - Use an empty statement for next label
>> 
>> Changes in v5:
>> - Export get_phy_c22_id when it is used
>> - Expose bind attributes, since there is no issue in doing so
>> - Use MDIO_BUS instead of MDIO_DEVICE
>> 
>> Changes in v4:
>> - Re-add documentation for axienet_xilinx_pcs_get that was accidentally
>>   removed
>> 
>> Changes in v3:
>> - Adjust axienet_xilinx_pcs_get for changes to pcs_find_fwnode API
>> - Call devm_pcs_register instead of devm_pcs_register_provider
>> 
>> Changes in v2:
>> - Add support for #pcs-cells
>> - Change compatible to just xlnx,pcs
>> - Drop PCS_ALTERA_TSE which was accidentally added while rebasing
>> - Rework xilinx_pcs_validate to just clear out half-duplex modes instead
>>   of constraining modes based on the interface.
>> 
>>  MAINTAINERS                  |   6 +
>>  drivers/net/pcs/Kconfig      |  22 ++
>>  drivers/net/pcs/Makefile     |   2 +
>>  drivers/net/pcs/pcs-xilinx.c | 427 +++++++++++++++++++++++++++++++++++
>>  drivers/net/phy/phy_device.c |   3 +-
>>  include/linux/phy.h          |   1 +
>>  6 files changed, 460 insertions(+), 1 deletion(-)
>>  create mode 100644 drivers/net/pcs/pcs-xilinx.c
>> 
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 0ac6ba5c40cb..496513837921 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -27060,6 +27060,12 @@ L:	netdev@vger.kernel.org
>>  S:	Orphan
>>  F:	drivers/net/ethernet/xilinx/ll_temac*
>>  
>> +XILINX PCS DRIVER
>> +M:	Sean Anderson <sean.anderson@linux.dev>
>> +S:	Maintained
>> +F:	Documentation/devicetree/bindings/net/xilinx,pcs.yaml
>> +F:	drivers/net/pcs/pcs-xilinx.c
>> +
>>  XILINX PWM DRIVER
>>  M:	Sean Anderson <sean.anderson@seco.com>
>>  S:	Maintained
>> diff --git a/drivers/net/pcs/Kconfig b/drivers/net/pcs/Kconfig
>> index f42839a0c332..e0223914362b 100644
>> --- a/drivers/net/pcs/Kconfig
>> +++ b/drivers/net/pcs/Kconfig
>> @@ -52,4 +52,26 @@ config PCS_RZN1_MIIC
>>  	  on RZ/N1 SoCs. This PCS converts MII to RMII/RGMII or can be set in
>>  	  pass-through mode for MII.
>>  
>> +config PCS_XILINX
>> +	tristate "Xilinx PCS driver"
>> +	default XILINX_AXI_EMAC
>> +	select COMMON_CLK
>> +	select GPIOLIB
>> +	select MDIO_BUS
>> +	select OF
>> +	select PCS
>> +	select PHYLINK
>> +	help
>> +	  PCS driver for the Xilinx 1G/2.5G Ethernet PCS/PMA or SGMII device.
>> +	  This device can either act as a PCS+PMA for 1000BASE-X or 2500BASE-X,
>> +	  or as a GMII-to-SGMII bridge. It can also switch between 1000BASE-X
>> +	  and SGMII dynamically if configured correctly when synthesized.
>> +	  Typical applications use this device on an FPGA connected to a GEM or
>> +	  TEMAC on the GMII side. The other side is typically connected to
>> +	  on-device gigabit transceivers, off-device SERDES devices using TBI,
>> +	  or LVDS IO resources directly.
>> +
>> +	  To compile this driver as a module, choose M here: the module
>> +	  will be called pcs-xilinx.
>> +
>>  endmenu
>> diff --git a/drivers/net/pcs/Makefile b/drivers/net/pcs/Makefile
>> index 35e3324fc26e..347afd91f034 100644
>> --- a/drivers/net/pcs/Makefile
>> +++ b/drivers/net/pcs/Makefile
>> @@ -10,3 +10,5 @@ obj-$(CONFIG_PCS_XPCS)		+= pcs_xpcs.o
>>  obj-$(CONFIG_PCS_LYNX)		+= pcs-lynx.o
>>  obj-$(CONFIG_PCS_MTK_LYNXI)	+= pcs-mtk-lynxi.o
>>  obj-$(CONFIG_PCS_RZN1_MIIC)	+= pcs-rzn1-miic.o
>> +obj-$(CONFIG_PCS_ALTERA_TSE)	+= pcs-altera-tse.o
> 
> There's something strange going-on here, as pcs-altera-tse was removed
> in v6.4 :)

Ah, well as it happens I have been working on this series since at least
5.10, so I guess it is left over. I will remove it for v7.

--Sean