phy: add a NO-OP phy driver

This driver is used to stub PHY operations in a driver (USB, SATA).
This is useful when the 'client' driver (USB, SATA, ...) uses the PHY
framework and there is no actual PHY harwdare to drive.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>

Documentation/devicetree/bindings/phy/no-op.txt

+NOP PHY driver
+
+This driver is used to stub PHY operations in a driver (USB, SATA).
+This is useful when the 'client' driver (USB, SATA, ...) uses the PHY framework
+and there is no actual PHY harwdare to drive.
+
+Required properties:
+- compatible     : must contain "nop-phy"
+- #phy-cells     : must contain <0>
+
+Example:
+
+nop_phy {
+	compatible = "nop-phy";
+	#phy-cells = <0>;
+};

drivers/phy/Kconfig

@@ -41,6 +41,24 @@ config PHY_SANDBOX
 	  This select a dummy sandbox PHY driver. It used only to implement
 	  the unit tests for the phy framework
 
+config NOP_PHY
+	bool "NOP PHY driver"
+	depends on PHY
+	help
+	  Support for a no-op PHY driver (stubbed PHY driver).
+
+	  This is useful when a driver uses the PHY framework but no real PHY
+	  hardware exists.
+
+config SPL_NOP_PHY
+	bool "NOP PHY driver in SPL"
+	depends on SPL_PHY
+	help
+	  Support for a no-op PHY driver (stubbed PHY driver) in the SPL.
+
+	  This is useful when a driver uses the PHY framework but no real PHY
+	  hardware exists.
+
 config PIPE3_PHY
 	bool "Support omap's PIPE3 PHY"
 	depends on PHY && ARCH_OMAP2PLUS

drivers/phy/Makefile

@@ -6,5 +6,6 @@
 #
 
 obj-$(CONFIG_$(SPL_)PHY) += phy-uclass.o
+obj-$(CONFIG_$(SPL_)NOP_PHY) += nop-phy.o
 obj-$(CONFIG_PHY_SANDBOX) += sandbox-phy.o
 obj-$(CONFIG_$(SPL_)PIPE3_PHY) += ti-pipe3-phy.o

drivers/phy/nop-phy.c

+/*
+ * Copyright (C) 2017 Texas Instruments Incorporated - http://www.ti.com/
+ * Written by Jean-Jacques Hiblot  <jjhiblot@ti.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/device.h>
+#include <generic-phy.h>
+
+static const struct udevice_id nop_phy_ids[] = {
+	{ .compatible = "nop-phy" },
+	{ }
+};
+
+static struct phy_ops nop_phy_ops = {
+};
+
+U_BOOT_DRIVER(nop_phy) = {
+	.name	= "nop_phy",
+	.id	= UCLASS_PHY,
+	.of_match = nop_phy_ids,
+	.ops = &nop_phy_ops,
+};