usb: core: add a wrapper for the USB PHYs on the HCD

Many SoC platforms have separate devices for the USB PHY which are
registered through the generic PHY framework. These PHYs have to be
enabled to make the USB controller actually work. They also have to be
disabled again on shutdown/suspend.

Currently (at least) the following HCI platform drivers are using custom
code to obtain all PHYs via devicetree for the roothub/controller and
disable/enable them when required:
- ehci-platform.c has ehci_platform_power_{on,off}
- xhci-mtk.c has xhci_mtk_phy_{init,exit,power_on,power_off}
- ohci-platform.c has ohci_platform_power_{on,off}

With this new wrapper the USB PHYs can be specified directly in the
USB controller's devicetree node (just like on the drivers listed
above). This allows SoCs like the Amlogic Meson GXL family to operate
correctly once this is wired up correctly. These SoCs use a dwc3
controller and require all USB PHYs to be initialized (if one of the USB
PHYs it not initialized then none of USB port works at all).

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Yixun Lan <yixun.lan@amlogic.com>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Tested-by: Neil Armstrong <narmstrong@baylibre.con>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/Makefile

@@ -6,7 +6,7 @@
 usbcore-y := usb.o hub.o hcd.o urb.o message.o driver.o
 usbcore-y += config.o file.o buffer.o sysfs.o endpoint.o
 usbcore-y += devio.o notify.o generic.o quirks.o devices.o
-usbcore-y += port.o
+usbcore-y += phy.o port.o
 
 usbcore-$(CONFIG_OF)		+= of.o
 usbcore-$(CONFIG_USB_PCI)		+= hcd-pci.o

drivers/usb/core/phy.c

@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * A wrapper for multiple PHYs which passes all phy_* function calls to
+ * multiple (actual) PHY devices. This is comes handy when initializing
+ * all PHYs on a HCD and to keep them all in the same state.
+ *
+ * Copyright (C) 2018 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
+ */
+
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/phy/phy.h>
+#include <linux/of.h>
+
+#include "phy.h"
+
+struct usb_phy_roothub {
+	struct phy		*phy;
+	struct list_head	list;
+};
+
+static struct usb_phy_roothub *usb_phy_roothub_alloc(struct device *dev)
+{
+	struct usb_phy_roothub *roothub_entry;
+
+	roothub_entry = devm_kzalloc(dev, sizeof(*roothub_entry), GFP_KERNEL);
+	if (!roothub_entry)
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&roothub_entry->list);
+
+	return roothub_entry;
+}
+
+static int usb_phy_roothub_add_phy(struct device *dev, int index,
+				   struct list_head *list)
+{
+	struct usb_phy_roothub *roothub_entry;
+	struct phy *phy = devm_of_phy_get_by_index(dev, dev->of_node, index);
+
+	if (IS_ERR_OR_NULL(phy)) {
+		if (!phy || PTR_ERR(phy) == -ENODEV)
+			return 0;
+		else
+			return PTR_ERR(phy);
+	}
+
+	roothub_entry = usb_phy_roothub_alloc(dev);
+	if (IS_ERR(roothub_entry))
+		return PTR_ERR(roothub_entry);
+
+	roothub_entry->phy = phy;
+
+	list_add_tail(&roothub_entry->list, list);
+
+	return 0;
+}
+
+struct usb_phy_roothub *usb_phy_roothub_init(struct device *dev)
+{
+	struct usb_phy_roothub *phy_roothub;
+	struct usb_phy_roothub *roothub_entry;
+	struct list_head *head;
+	int i, num_phys, err;
+
+	num_phys = of_count_phandle_with_args(dev->of_node, "phys",
+					      "#phy-cells");
+	if (num_phys <= 0)
+		return NULL;
+
+	phy_roothub = usb_phy_roothub_alloc(dev);
+	if (IS_ERR(phy_roothub))
+		return phy_roothub;
+
+	for (i = 0; i < num_phys; i++) {
+		err = usb_phy_roothub_add_phy(dev, i, &phy_roothub->list);
+		if (err)
+			goto err_out;
+	}
+
+	head = &phy_roothub->list;
+
+	list_for_each_entry(roothub_entry, head, list) {
+		err = phy_init(roothub_entry->phy);
+		if (err)
+			goto err_exit_phys;
+	}
+
+	return phy_roothub;
+
+err_exit_phys:
+	list_for_each_entry_continue_reverse(roothub_entry, head, list)
+		phy_exit(roothub_entry->phy);
+
+err_out:
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(usb_phy_roothub_init);
+
+int usb_phy_roothub_exit(struct usb_phy_roothub *phy_roothub)
+{
+	struct usb_phy_roothub *roothub_entry;
+	struct list_head *head;
+	int err, ret = 0;
+
+	if (!phy_roothub)
+		return 0;
+
+	head = &phy_roothub->list;
+
+	list_for_each_entry(roothub_entry, head, list) {
+		err = phy_exit(roothub_entry->phy);
+		if (err)
+			ret = ret;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_phy_roothub_exit);
+
+int usb_phy_roothub_power_on(struct usb_phy_roothub *phy_roothub)
+{
+	struct usb_phy_roothub *roothub_entry;
+	struct list_head *head;
+	int err;
+
+	if (!phy_roothub)
+		return 0;
+
+	head = &phy_roothub->list;
+
+	list_for_each_entry(roothub_entry, head, list) {
+		err = phy_power_on(roothub_entry->phy);
+		if (err)
+			goto err_out;
+	}
+
+	return 0;
+
+err_out:
+	list_for_each_entry_continue_reverse(roothub_entry, head, list)
+		phy_power_off(roothub_entry->phy);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(usb_phy_roothub_power_on);
+
+void usb_phy_roothub_power_off(struct usb_phy_roothub *phy_roothub)
+{
+	struct usb_phy_roothub *roothub_entry;
+
+	if (!phy_roothub)
+		return;
+
+	list_for_each_entry_reverse(roothub_entry, &phy_roothub->list, list)
+		phy_power_off(roothub_entry->phy);
+}
+EXPORT_SYMBOL_GPL(usb_phy_roothub_power_off);

drivers/usb/core/phy.h

@@ -0,0 +1,7 @@
+struct usb_phy_roothub;
+
+struct usb_phy_roothub *usb_phy_roothub_init(struct device *dev);
+int usb_phy_roothub_exit(struct usb_phy_roothub *phy_roothub);
+
+int usb_phy_roothub_power_on(struct usb_phy_roothub *phy_roothub);
+void usb_phy_roothub_power_off(struct usb_phy_roothub *phy_roothub);