[RFC PATCH 2/2] usb: hcd: Introduce CONFIG_USB_HCD_EXTERNAL_PHY option

[Valentine Barshak <valentine.barshak@cogentembedded.com>]

This adds external USB phy support to USB HCD driver that
allows to find and initialize external USB phy, bound to
the HCD when the HCD is added.
The usb_add_hcd function returns -EPROBE_DEFER if the USB
phy, bound to the HCD, is not ready.
If no USB phy is bound, the HCD is initialized as usual.

Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
---
 drivers/usb/core/hcd.c   | 20 ++++++++++++++++++++
 drivers/usb/host/Kconfig | 11 +++++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index d939521..da9c4ba 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2597,6 +2597,26 @@ int usb_add_hcd(struct usb_hcd *hcd,
 	int retval;
 	struct usb_device *rhdev;
 
+#ifdef CONFIG_USB_HCD_EXTERNAL_PHY
+	if (!hcd->phy) {
+		struct usb_phy *phy = usb_get_phy_dev(hcd->self.controller, 0);
+
+		if (IS_ERR(phy)) {
+			retval = PTR_ERR(phy);
+			if (retval = -EPROBE_DEFER)
+				return retval;
+		} else {
+			retval = usb_phy_init(phy);
+			if (retval) {
+				usb_put_phy(phy);
+				return retval;
+			}
+			hcd->phy = phy;
+			hcd->remove_phy = 1;
+		}
+	}
+#endif
+
 	dev_info(hcd->self.controller, "%s\n", hcd->product_desc);
 
 	/* Keep old behaviour if authorized_default is not in [0, 1]. */
diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index b3f20d7..2e1f2b0 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -706,3 +706,14 @@ config USB_HCD_TEST_MODE
 	  This option is of interest only to developers who need to validate
 	  their USB hardware designs.  It is not needed for normal use.  If
 	  unsure, say N.
+
+config USB_HCD_EXTERNAL_PHY
+	bool "Set up external USB phy bound to the USB HCD"
+	select USB_PHY
+	---help---
+	  Some USB host controllers require an external USB phy.
+	  This adds generic USB phy support to the USB HCD driver.
+	  When the HCD is being initialized, the HC driver searches
+	  for a USB phy, bound to the HCD. If no USB phy is bound
+	  to the HCD, the HCD is initialized as usual.
+	  If unsure, say N.
-- 
1.8.3.1