dt: net: add DWC EQoS binding

The Synopsys DWC EQoS is a configurable Ethernet MAC/DMA IP block which
supports multiple options for bus type, clocking and reset structure, and
feature list.

This patch imports the binding from the Linux kernel, including my V3
patch to extend the binding to cover the Tegra186, which is applied for
next-20160912. So far, my changes have been acked by Lars Persson, the
original author of the binding.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

doc/device-tree-bindings/net/snps,dwc-qos-ethernet.txt

@@ -0,0 +1,166 @@
+* 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: 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: 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.
+- snps,read-requests: Number of read requests that the AXI port can issue.
+  It depends on the SoC configuration.
+- snps,burst-map: Bitmap of allowed AXI burst lengts, with the LSB
+  representing 4, then 8 etc.
+- snps,txpbl: DMA Programmable burst length for the TX DMA
+- snps,rxpbl: DMA Programmable burst length for the RX DMA
+- snps,en-tx-lpi-clockgating: Enable gating of the MAC TX clock during
+  TX low-power mode.
+- phy-handle: See ethernet.txt file in the same directory
+- mdio device tree subnode: When the GMAC has a phy connected to its local
+    mdio, there must be device tree subnode with the following
+    required properties:
+    - compatible: Must be "snps,dwc-qos-ethernet-mdio".
+    - #address-cells: Must be <1>.
+    - #size-cells: Must be <0>.
+
+    For each phy on the mdio bus, there must be a node with the following
+    fields:
+
+    - reg: phy id used to communicate to phy.
+    - device_type: Must be "ethernet-phy".
+    - fixed-mode device tree subnode: see fixed-link.txt in the same directory
+
+Examples:
+ethernet2@40010000 {
+	clock-names = "phy_ref_clk", "apb_pclk";
+	clocks = <&clkc 17>, <&clkc 15>;
+	compatible = "snps,dwc-qos-ethernet-4.10";
+	interrupt-parent = <&intc>;
+	interrupts = <0x0 0x1e 0x4>;
+	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;
+	snps,write-requests = <2>;
+	snps,read-requests = <16>;
+	snps,burst-map = <0x7>;
+	snps,txpbl = <8>;
+	snps,rxpbl = <2>;
+
+	dma-coherent;
+
+	mdio {
+		#address-cells = <0x1>;
+		#size-cells = <0x0>;
+		phy2: phy@1 {
+			compatible = "ethernet-phy-ieee802.3-c22";
+			device_type = "ethernet-phy";
+			reg = <0x1>;
+		};
+	};
+};