dt: net: enhance DWC EQoS binding to support Tegra186

The Synopsys DWC EQoS is a configurable IP block which supports multiple
options for bus type, clocking and reset structure, and feature list.
Extend the DT binding to define a "compatible value" for the configuration
contained in NVIDIA's Tegra186 SoC, and define some new properties and
list property entries required by that configuration.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/net/snps,dwc-qos-ethernet.txt

 * Synopsys DWC Ethernet QoS IP version 4.10 driver (GMAC)
 
+This binding supports the Synopsys Designware Ethernet QoS (Quality Of Service)
+IP block. The IP supports multiple options for bus type, clocking and reset
+structure, and feature list. Consequently, a number of properties and list
+entries in properties are marked as optional, or only required in specific HW
+configurations.
 
 Required properties:
-- compatible: Should be "snps,dwc-qos-ethernet-4.10"
+- compatible: One of:
+  - "axis,artpec6-eqos", "snps,dwc-qos-ethernet-4.10"
+    Represents the IP core when integrated into the Axis ARTPEC-6 SoC.
+  - "nvidia,tegra186-eqos", "snps,dwc-qos-ethernet-4.10"
+    Represents the IP core when integrated into the NVIDIA Tegra186 SoC.
+  - "snps,dwc-qos-ethernet-4.10"
+    This combination is deprecated. It should be treated as equivalent to
+    "axis,artpec6-eqos", "snps,dwc-qos-ethernet-4.10". It is supported to be
+    compatible with earlier revisions of this binding.
 - reg: Address and length of the register set for the device
-- clocks: Phandles to the reference clock and the bus clock
-- clock-names: Should be "phy_ref_clk" for the reference clock and "apb_pclk"
-  for the bus clock.
+- clocks: Phandle and clock specifiers for each entry in clock-names, in the
+  same order. See ../clock/clock-bindings.txt.
+- clock-names: May contain any/all of the following depending on the IP
+  configuration, in any order:
+  - "tx"
+    The EQOS transmit path clock. The HW signal name is clk_tx_i.
+    In some configurations (e.g. GMII/RGMII), this clock also drives the PHY TX
+    path. In other configurations, other clocks (such as tx_125, rmii) may
+    drive the PHY TX path.
+  - "rx"
+    The EQOS receive path clock. The HW signal name is clk_rx_i.
+    In some configurations (e.g. GMII/RGMII), this clock is derived from the
+    PHY's RX clock output. In other configurations, other clocks (such as
+    rx_125, rmii) may drive the EQOS RX path.
+    In cases where the PHY clock is directly fed into the EQOS receive path
+    without intervening logic, the DT need not represent this clock, since it
+    is assumed to be fully under the control of the PHY device/driver. In
+    cases where SoC integration adds additional logic to this path, such as a
+    SW-controlled clock gate, this clock should be represented in DT.
+  - "slave_bus"
+    The CPU/slave-bus (CSR) interface clock. This applies to any bus type;
+    APB, AHB, AXI, etc. The HW signal name is hclk_i (AHB) or clk_csr_i (other
+    buses).
+  - "master_bus"
+    The master bus interface clock. Only required in configurations that use a
+    separate clock for the master and slave bus interfaces. The HW signal name
+    is hclk_i (AHB) or aclk_i (AXI).
+  - "ptp_ref"
+    The PTP reference clock. The HW signal name is clk_ptp_ref_i.
+  - "phy_ref_clk"
+    This clock is deprecated and should not be used by new compatible values.
+    It is equivalent to "tx".
+  - "apb_pclk"
+    This clock is deprecated and should not be used by new compatible values.
+    It is equivalent to "slave_bus".
+
+  Note: Support for additional IP configurations may require adding the
+  following clocks to this list in the future: clk_rx_125_i, clk_tx_125_i,
+  clk_pmarx_0_i, clk_pmarx1_i, clk_rmii_i, clk_revmii_rx_i, clk_revmii_tx_i.
+  Configurations exist where multiple similar clocks are used at once, e.g. all
+  of clk_rx_125_i, clk_pmarx_0_i, clk_pmarx1_i. For this reason it is best to
+  extend the binding with a separate clock-names entry for each of those RX
+  clocks, rather than repurposing the existing "rx" clock-names entry as a
+  generic/logical clock in a similar fashion to "master_bus" and "slave_bus".
+  This will allow easy support for configurations that support multiple PHY
+  interfaces using a mux, and hence need to have explicit control over
+  specific RX clocks.
+
+  The following compatible values require the following set of clocks:
+  - "nvidia,tegra186-eqos", "snps,dwc-qos-ethernet-4.10":
+    - "slave_bus"
+    - "master_bus"
+    - "rx"
+    - "tx"
+    - "ptp_ref"
+  - "axis,artpec6-eqos", "snps,dwc-qos-ethernet-4.10":
+    - "slave_bus"
+    - "master_bus"
+    - "tx"
+    - "ptp_ref"
+  - "snps,dwc-qos-ethernet-4.10" (deprecated):
+    - "phy_ref_clk"
+    - "apb_clk"
 - interrupt-parent: Should be the phandle for the interrupt controller
   that services interrupts for this device
 - interrupts: Should contain the core's combined interrupt signal
 - phy-mode: See ethernet.txt file in the same directory
+- resets: Phandle and reset specifiers for each entry in reset-names, in the
+  same order. See ../reset/reset.txt.
+- reset-names: May contain any/all of the following depending on the IP
+  configuration, in any order:
+  - "eqos". The reset to the entire module. The HW signal name is hreset_n
+    (AHB) or aresetn_i (AXI).
+
+  The following compatible values require the following set of resets:
+  (the reset properties may be omitted if empty)
+  - "nvidia,tegra186-eqos", "snps,dwc-qos-ethernet-4.10":
+    - "eqos".
+  - "axis,artpec6-eqos", "snps,dwc-qos-ethernet-4.10":
+    - None.
+  - "snps,dwc-qos-ethernet-4.10" (deprecated):
+    - None.
 
 Optional properties:
 - dma-coherent: Present if dma operations are coherent
 - mac-address: See ethernet.txt in the same directory
 - local-mac-address: See ethernet.txt in the same directory
+- phy-reset-gpios: Phandle and specifier for any GPIO used to reset the PHY.
+  See ../gpio/gpio.txt.
 - snps,en-lpi: If present it enables use of the AXI low-power interface
 - snps,write-requests: Number of write requests that the AXI port can issue.
   It depends on the SoC configuration.
@@ -52,6 +142,7 @@ ethernet2@40010000 {
 	reg = <0x40010000 0x4000>;
 	phy-handle = <&phy2>;
 	phy-mode = "gmii";
+	phy-reset-gpios = <&gpioctlr 43 GPIO_ACTIVE_LOW>;
 
 	snps,en-tx-lpi-clockgating;
 	snps,en-lpi;