usb: host: xhci-plat: Create platform device for onboard hubs in probe()

Call onboard_hub_create/destroy_pdevs() from  _probe()/_remove()
to create/destroy platform devices for onboard USB hubs that may
be connected to the root hub of the controller. These functions
are a NOP unless CONFIG_USB_ONBOARD_HUB=y/m.

Also add a field to struct xhci_hcd to keep track of the onboard hub
platform devices that are owned by the xHCI.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Link: https://lore.kernel.org/r/20210609150159.v12.4.I7a3a7d9d2126c34079b1cab87aa0b2ec3030f9b7@changeidSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/Kconfig

@@ -54,6 +54,7 @@ config USB_XHCI_PCI_RENESAS
 config USB_XHCI_PLATFORM
 	tristate "Generic xHCI driver for a platform device"
 	select USB_XHCI_RCAR if ARCH_RENESAS
+	depends on USB_ONBOARD_HUB || !USB_ONBOARD_HUB
 	help
 	  Adds an xHCI host driver for a generic platform device, which
 	  provides a memory space and an irq.

drivers/usb/host/xhci-plat.c

@@ -15,6 +15,7 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/usb/onboard_hub.h>
 #include <linux/usb/phy.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
@@ -374,6 +375,9 @@ static int xhci_plat_probe(struct platform_device *pdev)
 	 */
 	pm_runtime_forbid(&pdev->dev);
 
+	INIT_LIST_HEAD(&xhci->onboard_hub_devs);
+	onboard_hub_create_pdevs(hcd->self.root_hub, &xhci->onboard_hub_devs);
+
 	return 0;
 
 
@@ -420,6 +424,8 @@ static int xhci_plat_remove(struct platform_device *dev)
 	usb_remove_hcd(hcd);
 	usb_put_hcd(shared_hcd);
 
+	onboard_hub_destroy_pdevs(&xhci->onboard_hub_devs);
+
 	clk_disable_unprepare(clk);
 	clk_disable_unprepare(reg_clk);
 	usb_put_hcd(hcd);

drivers/usb/host/xhci.h

@@ -1920,6 +1920,8 @@ struct xhci_hcd {
 	struct dentry		*debugfs_slots;
 	struct list_head	regset_list;
 
+	struct list_head	onboard_hub_devs;
+
 	void			*dbc;
 	/* platform-specific data -- must come last */
 	unsigned long		priv[] __aligned(sizeof(s64));