[PATCH 2/2] phy: rcar-gen3-usb2: add fallback binding

[Simon Horman]

In the case of Renesas R-Car hardware we know that there are generations of
SoCs, e.g. Gen 2 and Gen 3. But beyond that its not clear what the
relationship between IP blocks might be. For example, I believe that
r8a7790 is older than r8a7791 but that doesn't imply that the latter is a
descendant of the former or vice versa.

We can, however, by examining the documentation and behaviour of the
hardware at run-time observe that the current driver implementation appears
to be compatible with the IP blocks on SoCs within a given generation.

For the above reasons and convenience when enabling new SoCs a
per-generation fallback compatibility string scheme being adopted for
drivers for Renesas SoCs.

Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
---
 Documentation/devicetree/bindings/phy/rcar-gen3-phy-usb2.txt | 10 ++++++++--
 drivers/phy/phy-rcar-gen3-usb2.c                             |  1 +
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/phy/rcar-gen3-phy-usb2.txt b/Documentation/devicetree/bindings/phy/rcar-gen3-phy-usb2.txt
index 2390e4e9c84c..1da9bb978824 100644
--- a/Documentation/devicetree/bindings/phy/rcar-gen3-phy-usb2.txt
+++ b/Documentation/devicetree/bindings/phy/rcar-gen3-phy-usb2.txt
@@ -6,6 +6,12 @@ This file provides information on what the device node for the R-Car generation
 Required properties:
 - compatible: "renesas,usb2-phy-r8a7795" if the device is a part of an R8A7795
 	      SoC.
+	      "renesas,usb2-phy-gen3" for a generic R-Car Gen3 compatible device.
+
+	      When compatible with the generic version, nodes must list the
+	      SoC-specific version corresponding to the platform first
+	      followed by the generic version.
+
 - reg: offset and length of the partial USB 2.0 Host register block.
 - reg-names: must be "usb2_host".
 - clocks: clock phandle and specifier pair(s).
@@ -23,7 +29,7 @@ peripheral at that channel:
 Example (R-Car H3):
 
 	usb-phy@ee080200 {
-		compatible = "renesas,usb2-phy-r8a7795";
+		compatible = "renesas,usb2-phy-r8a7795","renesas,usb2-phy-gen3";
 		reg = <0 0xee080200 0 0x700>, <0 0xe6590100 0 0x100>;
 		reg-names = "usb2_host", "hsusb";
 		interrupts = <GIC_SPI 108 IRQ_TYPE_LEVEL_HIGH>;
@@ -32,7 +38,7 @@ Example (R-Car H3):
 	};
 
 	usb-phy@ee0a0200 {
-		compatible = "renesas,usb2-phy-r8a7795";
+		compatible = "renesas,usb2-phy-r8a7795","renesas,usb2-phy-gen3";
 		reg = <0 0xee0a0200 0 0x700>;
 		reg-names = "usb2_host";
 		clocks = <&mstp7_clks R8A7795_CLK_EHCI0>;
diff --git a/drivers/phy/phy-rcar-gen3-usb2.c b/drivers/phy/phy-rcar-gen3-usb2.c
index ef332ef4abc7..ddd171814d36 100644
--- a/drivers/phy/phy-rcar-gen3-usb2.c
+++ b/drivers/phy/phy-rcar-gen3-usb2.c
@@ -303,6 +303,7 @@ static irqreturn_t rcar_gen3_phy_usb2_irq(int irq, void *_ch)
 
 static const struct of_device_id rcar_gen3_phy_usb2_match_table[] = {
 	{ .compatible = "renesas,usb2-phy-r8a7795" },
+	{ .compatible = "renesas,usb2-phy-gen3" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, rcar_gen3_phy_usb2_match_table);
-- 
2.1.4