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SubjectRe: [PATCH net-next v2 01/35] dt-bindings: phy: Add QorIQ SerDes binding
On Tue, Jun 28, 2022 at 06:13:30PM -0400, Sean Anderson wrote:
> This adds a binding for the SerDes module found on QorIQ processors. The
> phy reference has two cells, one for the first lane and one for the
> last. This should allow for good support of multi-lane protocols when
> (if) they are added. There is no protocol option, because the driver is
> designed to be able to completely reconfigure lanes at runtime.
> Generally, the phy consumer can select the appropriate protocol using
> set_mode. For the most part there is only one protocol controller
> (consumer) per lane/protocol combination. The exception to this is the
> B4860 processor, which has some lanes which can be connected to
> multiple MACs. For that processor, I anticipate the easiest way to
> resolve this will be to add an additional cell with a "protocol
> controller instance" property.
>
> Each serdes has a unique set of supported protocols (and lanes). The
> support matrix is stored in the driver and is selected based on the
> compatible string. It is anticipated that a new compatible string will
> need to be added for each serdes on each SoC that drivers support is
> added for. There is no "generic" compatible string for this reason.
>
> There are two PLLs, each of which can be used as the master clock for
> each lane. Each PLL has its own reference. For the moment they are
> required, because it simplifies the driver implementation. Absent
> reference clocks can be modeled by a fixed-clock with a rate of 0.
>
> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
> ---
>
> Changes in v2:
> - Add #clock-cells. This will allow using assigned-clocks* to configure
> the PLLs.
> - Allow a value of 1 for phy-cells. This allows for compatibility with
> the similar (but according to Ioana Ciornei different enough) lynx-28g
> binding.
> - Document phy cells in the description
> - Document the structure of the compatible strings
> - Fix example binding having too many cells in regs
> - Move compatible first
> - Refer to the device in the documentation, rather than the binding
> - Remove minItems
> - Rename to fsl,lynx-10g.yaml
> - Use list for clock-names
>
> .../devicetree/bindings/phy/fsl,lynx-10g.yaml | 93 +++++++++++++++++++
> 1 file changed, 93 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/phy/fsl,lynx-10g.yaml
>
> diff --git a/Documentation/devicetree/bindings/phy/fsl,lynx-10g.yaml b/Documentation/devicetree/bindings/phy/fsl,lynx-10g.yaml
> new file mode 100644
> index 000000000000..b5a6f631df9f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/phy/fsl,lynx-10g.yaml
> @@ -0,0 +1,93 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/phy/fsl,lynx-10g.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: NXP Lynx 10G SerDes
> +
> +maintainers:
> + - Sean Anderson <sean.anderson@seco.com>
> +
> +description: |
> + These Lynx "SerDes" devices are found in NXP's QorIQ line of processors. The
> + SerDes provides up to eight lanes. Each lane may be configured individually,
> + or may be combined with adjacent lanes for a multi-lane protocol. The SerDes
> + supports a variety of protocols, including up to 10G Ethernet, PCIe, SATA, and
> + others. The specific protocols supported for each lane depend on the
> + particular SoC.
> +
> +properties:
> + compatible:
> + description: |
> + Each compatible is of the form "fsl,<soc-name>-serdes-<instance>".
> + Although many registers are compatible between different SoCs, the
> + supported protocols and lane assignments tend to be unique to each SerDes.
> + Additionally, the method of activating protocols may also be unique.

We typically have properties for handling these variables. Numbering
instances is something we avoid.

> + Because of this, each SerDes instance will need its own compatible string.

> + In cases where two SoCs share the same SerDes implementation (such as the
> + LS1046A and LS1026A), both SoCs should share the same compatible strings.

No, not unless the 2 parts are just fuse or package pinout differences.
Otherwise, there's always the chance they are not 'the same' and have
different bugs.

You could have "fsl,ls1046a-serdes", "fsl,ls1026a-serdes" (whichever SoC
is older last) if you think they are 'the same'.


> + enum:
> + - fsl,ls1046a-serdes-1
> + - fsl,ls1046a-serdes-2
> +
> + "#clock-cells":
> + const: 1
> + description: |
> + The cell contains the index of the PLL, starting from 0. Note that when
> + assigning a rate to a PLL, the PLLs' rates are divided by 1000 to avoid
> + overflow. A rate of 5000000 corresponds to 5GHz.
> +
> + "#phy-cells":
> + minimum: 1
> + maximum: 2
> + description: |
> + The cells contain the following arguments:
> + - The first lane in the group. Lanes are numbered based on the register
> + offsets, not the I/O ports. This corresponds to the letter-based ("Lane
> + A") naming scheme, and not the number-based ("Lane 0") naming scheme. On
> + most SoCs, "Lane A" is "Lane 0", but not always.
> + - Last lane. For single-lane protocols, this should be the same as the
> + first lane.
> + If no lanes in a SerDes can be grouped, then #phy-cells may be 1, and the
> + first cell will specify the only lane in the group.

Usually when we have per lane phys, the consumer side will have a 'phys'
entry per lane.

Having a variable number of cells isn't great either. We usually only do
that when we have to extend an existing binding.

> +
> + clocks:
> + maxItems: 2
> + description: |
> + Clock for each PLL reference clock input.
> +
> + clock-names:
> + items:
> + - enum: &clocks
> + - ref0
> + - ref1
> + - enum: *clocks

Whoa, there's a first. Don't use YAML anchors and references. We only
support JSON subset of YAML.

> +
> + reg:
> + maxItems: 1
> +
> +required:
> + - "#clock-cells"
> + - "#phy-cells"
> + - compatible
> + - clocks
> + - clock-names
> + - reg
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + serdes1: phy@1ea0000 {
> + #clock-cells = <1>;
> + #phy-cells = <2>;
> + compatible = "fsl,ls1046a-serdes-1";
> + reg = <0x1ea0000 0x2000>;
> + clocks = <&clk_100mhz>, <&clk_156mhz>;
> + clock-names = "ref0", "ref1";
> + assigned-clocks = <&serdes1 0>;
> + assigned-clock-rates = <5000000>;
> + };
> +
> +...
> --
> 2.35.1.1320.gc452695387.dirty
>
>

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