usb: misc: onboard_hub: rename to onboard_dev

This patch prepares onboad_hub to support non-hub devices by renaming
the driver files and their content, the headers and their references.

The comments and descriptions have been slightly modified to keep
coherence and account for the specific cases that only affect onboard
hubs (e.g. peer-hub).

The "hub" variables in functions where "dev" (and similar names) variables
already exist have been renamed to onboard_dev for clarity, which adds a
few lines in cases where more than 80 characters are used.

No new functionality has been added.

Acked-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Javier Carrasco <javier.carrasco@wolfvision.net>
Link: https://lore.kernel.org/r/20240325-onboard_xvf3500-v8-2-29e3f9222922@wolfvision.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 144 insertions, 0 deletions

diff --git a/drivers/usb/misc/onboard_usb_dev_pdevs.c b/drivers/usb/misc/onboard_usb_dev_pdevs.c
new file mode 100644
index 000000000000..722504752ce3
--- /dev/null
+++ b/drivers/usb/misc/onboard_usb_dev_pdevs.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * API for creating and destroying USB onboard platform devices
+ *
+ * Copyright (c) 2022, Google LLC
+ */
+
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/usb.h>
+#include <linux/usb/hcd.h>
+#include <linux/usb/of.h>
+#include <linux/usb/onboard_dev.h>
+
+#include "onboard_usb_dev.h"
+
+struct pdev_list_entry {
+	struct platform_device *pdev;
+	struct list_head node;
+};
+
+static bool of_is_onboard_usb_dev(struct device_node *np)
+{
+	return !!of_match_node(onboard_dev_match, np);
+}
+
+/**
+ * onboard_dev_create_pdevs -- create platform devices for onboard USB devices
+ * @parent_hub	: parent hub to scan for connected onboard devices
+ * @pdev_list	: list of onboard platform devices owned by the parent hub
+ *
+ * Creates a platform device for each supported onboard device that is connected
+ * to the given parent hub. The platform device is in charge of initializing the
+ * device (enable regulators, take the device out of reset, ...). For onboard
+ * hubs, it can optionally control whether the device remains powered during
+ * system suspend or not.
+ *
+ * To keep track of the platform devices they are added to a list that is owned
+ * by the parent hub.
+ *
+ * Some background about the logic in this function, which can be a bit hard
+ * to follow:
+ *
+ * Root hubs don't have dedicated device tree nodes, but use the node of their
+ * HCD. The primary and secondary HCD are usually represented by a single DT
+ * node. That means the root hubs of the primary and secondary HCD share the
+ * same device tree node (the HCD node). As a result this function can be called
+ * twice with the same DT node for root hubs. We only want to create a single
+ * platform device for each physical onboard device, hence for root hubs the
+ * loop is only executed for the root hub of the primary HCD. Since the function
+ * scans through all child nodes it still creates pdevs for onboard devices
+ * connected to the root hub of the secondary HCD if needed.
+ *
+ * Further there must be only one platform device for onboard hubs with a peer
+ * hub (the hub is a single physical device). To achieve this two measures are
+ * taken: pdevs for onboard hubs with a peer are only created when the function
+ * is called on behalf of the parent hub that is connected to the primary HCD
+ * (directly or through other hubs). For onboard hubs connected to root hubs
+ * the function processes the nodes of both peers. A platform device is only
+ * created if the peer hub doesn't have one already.
+ */
+void onboard_dev_create_pdevs(struct usb_device *parent_hub, struct list_head *pdev_list)
+{
+	int i;
+	struct usb_hcd *hcd = bus_to_hcd(parent_hub->bus);
+	struct device_node *np, *npc;
+	struct platform_device *pdev;
+	struct pdev_list_entry *pdle;
+
+	if (!parent_hub->dev.of_node)
+		return;
+
+	if (!parent_hub->parent && !usb_hcd_is_primary_hcd(hcd))
+		return;
+
+	for (i = 1; i <= parent_hub->maxchild; i++) {
+		np = usb_of_get_device_node(parent_hub, i);
+		if (!np)
+			continue;
+
+		if (!of_is_onboard_usb_dev(np))
+			goto node_put;
+
+		npc = of_parse_phandle(np, "peer-hub", 0);
+		if (npc) {
+			if (!usb_hcd_is_primary_hcd(hcd)) {
+				of_node_put(npc);
+				goto node_put;
+			}
+
+			pdev = of_find_device_by_node(npc);
+			of_node_put(npc);
+
+			if (pdev) {
+				put_device(&pdev->dev);
+				goto node_put;
+			}
+		}
+
+		pdev = of_platform_device_create(np, NULL, &parent_hub->dev);
+		if (!pdev) {
+			dev_err(&parent_hub->dev,
+				"failed to create platform device for onboard dev '%pOF'\n", np);
+			goto node_put;
+		}
+
+		pdle = kzalloc(sizeof(*pdle), GFP_KERNEL);
+		if (!pdle) {
+			of_platform_device_destroy(&pdev->dev, NULL);
+			goto node_put;
+		}
+
+		pdle->pdev = pdev;
+		list_add(&pdle->node, pdev_list);
+
+node_put:
+		of_node_put(np);
+	}
+}
+EXPORT_SYMBOL_GPL(onboard_dev_create_pdevs);
+
+/**
+ * onboard_dev_destroy_pdevs -- free resources of onboard platform devices
+ * @pdev_list	: list of onboard platform devices
+ *
+ * Destroys the platform devices in the given list and frees the memory associated
+ * with the list entry.
+ */
+void onboard_dev_destroy_pdevs(struct list_head *pdev_list)
+{
+	struct pdev_list_entry *pdle, *tmp;
+
+	list_for_each_entry_safe(pdle, tmp, pdev_list, node) {
+		list_del(&pdle->node);
+		of_platform_device_destroy(&pdle->pdev->dev, NULL);
+		kfree(pdle);
+	}
+}
+EXPORT_SYMBOL_GPL(onboard_dev_destroy_pdevs);