Re: [PATCH] dt: net: enhance DWC EQoS binding to support Tegra186

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Hi Stephen,

Nice to see the driver used in other chips. I have some comments below.

Best Regards,
 Lars


On 08/23/2016 10:47 PM, Stephen Warren wrote:
From: Stephen Warren <swarren@xxxxxxxxxx>

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: Stephen Warren <swarren@xxxxxxxxxx>
---
 .../bindings/net/snps,dwc-qos-ethernet.txt         | 60 ++++++++++++++++++++--
 1 file changed, 56 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/snps,dwc-qos-ethernet.txt b/Documentation/devicetree/bindings/net/snps,dwc-qos-ethernet.txt
index 51f8d2eba8d8..6cd4129364a9 100644
--- a/Documentation/devicetree/bindings/net/snps,dwc-qos-ethernet.txt
+++ b/Documentation/devicetree/bindings/net/snps,dwc-qos-ethernet.txt
@@ -1,21 +1,72 @@
 * 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:
+  - "snps,dwc-qos-ethernet-4.10"
+  - "nvidia,tegra186-eqos", "snps,dwc-qos-ethernet-4.10"
 - 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:
+  - "phy_ref_clk". The reference clock provided directly to the PHY.
+    Only required if under SW control, i.e. not provided by some fixed source
+    such as a crystal.

I realize now that the clock name phy_ref_clock is slightly misleading. It represents the source of the GMII GTXCLK signal to the phy.

In our chip it is the same clock that drives clk_tx_i for GMII 1 Gb/s modes, but I agree that we should have a separate binding for the tx clock.

So update the description of phy_ref_clk to mention GTXCLK.

+  - "apb_pclk" (alternate name "slave_bus"; only one alternate must appear).
+    The CPU/slave-bus (CSR) interface clock. Despite the name, 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).
+  - "rx". The receive path clock. The HW signal name is clk_rx_i.
+  - "tx". The transmit path clock. The HW signal name is clk_tx_i.
+  - "ptp_ref". The PTP reference clock. The HW signal name is clk_ptp_ref_i.
+
+  Note: Support for additional HW 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.
+
+  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"
+  - "snps,dwc-qos-ethernet-4.10":
+    - "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 clocks:
s/clocks/resets/

+  (the reset properties may be omitted if empty)
+  - "nvidia,tegra186-eqos", "snps,dwc-qos-ethernet-4.10":
+    - "eqos".
+  - "snps,dwc-qos-ethernet-4.10":
+    - 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.

IMHO the phy reset gpio belongs in the binding for the PHY. I notice some other ethernet drivers have this, but the PHY should be managed entirely through the phylib and any special handling for reset can be hidden in phy specific drivers.


 - 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 +103,7 @@ 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;


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