[RFCv3 usb-next 2/3] usb: host: add a generic platform USB roothub driver

[Martin Blumenstingl]

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}

These drivers are not using the generic devicetree USB device bindings
yet which were only introduced recently (documentation is available in
devicetree/bindings/usb/usb-device.txt).
With this new driver the usb2-phy and usb3-phy can be specified directly
in the child-node of the corresponding port of the roothub via
devicetree. This can be extended by not just parsing PHYs (some of the
other drivers listed above are for example also parsing a list of clocks
as well) when required.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl at googlemail.com>
---
 drivers/usb/host/Kconfig            |   3 +
 drivers/usb/host/Makefile           |   2 +
 drivers/usb/host/platform-roothub.c | 180 ++++++++++++++++++++++++++++++++++++
 drivers/usb/host/platform-roothub.h |  12 +++
 4 files changed, 197 insertions(+)
 create mode 100644 drivers/usb/host/platform-roothub.c
 create mode 100644 drivers/usb/host/platform-roothub.h

diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index fa5692dec832..b8b05c786b2a 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -805,6 +805,9 @@ config USB_HCD_SSB
 
 	  If unsure, say N.
 
+config USB_PLATFORM_ROOTHUB
+	bool
+
 config USB_HCD_TEST_MODE
 	bool "HCD test mode support"
 	---help---
diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
index cf2691fffcc0..dc817f82d632 100644
--- a/drivers/usb/host/Makefile
+++ b/drivers/usb/host/Makefile
@@ -29,6 +29,8 @@ obj-$(CONFIG_USB_WHCI_HCD)	+= whci/
 
 obj-$(CONFIG_USB_PCI)	+= pci-quirks.o
 
+obj-$(CONFIG_USB_PLATFORM_ROOTHUB)	+= platform-roothub.o
+
 obj-$(CONFIG_USB_EHCI_HCD)	+= ehci-hcd.o
 obj-$(CONFIG_USB_EHCI_PCI)	+= ehci-pci.o
 obj-$(CONFIG_USB_EHCI_HCD_PLATFORM)	+= ehci-platform.o
diff --git a/drivers/usb/host/platform-roothub.c b/drivers/usb/host/platform-roothub.c
new file mode 100644
index 000000000000..70d2d97aa8b2
--- /dev/null
+++ b/drivers/usb/host/platform-roothub.c
@@ -0,0 +1,180 @@
+/*
+ * platform roothub driver - a virtual PHY device which passes all phy_*
+ * function calls to multiple (actual) PHY devices. This is comes handy when
+ * initializing all PHYs on a root-hub (to keep them all in the same state).
+ *
+ * Copyright (C) 2017 Martin Blumenstingl <martin.blumenstingl at googlemail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/phy/phy.h>
+#include <linux/of.h>
+#include <linux/usb/of.h>
+
+#include "platform-roothub.h"
+
+#define ROOTHUB_PORTNUM		0
+
+struct platform_roothub {
+	struct phy		*phy;
+	struct list_head	list;
+};
+
+static struct platform_roothub *platform_roothub_alloc(struct device *dev)
+{
+	struct platform_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 platform_roothub_add_phy(struct device *dev,
+				    struct device_node *port_np,
+				    const char *con_id, struct list_head *list)
+{
+	struct platform_roothub *roothub_entry;
+	struct phy *phy = devm_of_phy_get(dev, port_np, con_id);
+
+	if (IS_ERR_OR_NULL(phy)) {
+		if (!phy || PTR_ERR(phy) == -ENODEV)
+			return 0;
+		else
+			return PTR_ERR(phy);
+	}
+
+	roothub_entry = platform_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 platform_roothub *platform_roothub_init(struct device *dev)
+{
+	struct device_node *roothub_np, *port_np;
+	struct platform_roothub *plat_roothub;
+	struct platform_roothub *roothub_entry;
+	struct list_head *head;
+	int err;
+
+	roothub_np = usb_of_get_child_node(dev->of_node, ROOTHUB_PORTNUM);
+	if (!of_device_is_available(roothub_np))
+		return NULL;
+
+	plat_roothub = platform_roothub_alloc(dev);
+	if (IS_ERR(plat_roothub))
+		return plat_roothub;
+
+	for_each_available_child_of_node(roothub_np, port_np) {
+		err = platform_roothub_add_phy(dev, port_np, "usb2-phy",
+					       &plat_roothub->list);
+		if (err)
+			goto err_out;
+
+		err = platform_roothub_add_phy(dev, port_np, "usb3-phy",
+					       &plat_roothub->list);
+		if (err)
+			goto err_out;
+	}
+
+	head = &plat_roothub->list;
+
+	list_for_each_entry(roothub_entry, head, list) {
+		err = phy_init(roothub_entry->phy);
+		if (err)
+			goto err_exit_phys;
+	}
+
+	return plat_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(platform_roothub_init);
+
+int platform_roothub_exit(struct platform_roothub *plat_roothub)
+{
+	struct platform_roothub *roothub_entry;
+	struct list_head *head;
+	int err, ret = 0;
+
+	if (!plat_roothub)
+		return 0;
+
+	head = &plat_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(platform_roothub_exit);
+
+int platform_roothub_power_on(struct platform_roothub *plat_roothub)
+{
+	struct platform_roothub *roothub_entry;
+	struct list_head *head;
+	int err;
+
+	if (!plat_roothub)
+		return 0;
+
+	head = &plat_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(platform_roothub_power_on);
+
+int platform_roothub_power_off(struct platform_roothub *plat_roothub)
+{
+	struct platform_roothub *roothub_entry;
+	int err, ret = 0;
+
+	if (!plat_roothub)
+		return 0;
+
+	list_for_each_entry_reverse(roothub_entry, &plat_roothub->list, list) {
+		err = phy_power_off(roothub_entry->phy);
+		if (err)
+			ret = err;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(platform_roothub_power_off);
diff --git a/drivers/usb/host/platform-roothub.h b/drivers/usb/host/platform-roothub.h
new file mode 100644
index 000000000000..0b801da66918
--- /dev/null
+++ b/drivers/usb/host/platform-roothub.h
@@ -0,0 +1,12 @@
+#ifndef USB_HOST_PLATFORM_ROOTHUB_H
+#define USB_HOST_PLATFORM_ROOTHUB_H
+
+struct platform_roothub;
+
+struct platform_roothub *platform_roothub_init(struct device *dev);
+int platform_roothub_exit(struct platform_roothub *plat_roothub);
+
+int platform_roothub_power_on(struct platform_roothub *plat_roothub);
+int platform_roothub_power_off(struct platform_roothub *plat_roothub);
+
+#endif /* USB_HOST_PLATFORM_ROOTHUB_H */
-- 
2.14.1