On Wednesday 14 May 2014 17:33:02 Andrew Bresticker wrote:

+
+int tegra_xhci_register_mbox_notifier(struct notifier_block *nb)
+{
+	int ret;
+
+	mutex_lock(&tegra_xhci_mbox_lock);
+	ret = raw_notifier_chain_register(&tegra_xhci_mbox_notifiers, nb);
+	mutex_unlock(&tegra_xhci_mbox_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(tegra_xhci_register_mbox_notifier);
+
+void tegra_xhci_unregister_mbox_notifier(struct notifier_block *nb)
+{
+	mutex_lock(&tegra_xhci_mbox_lock);
+	raw_notifier_chain_unregister(&tegra_xhci_mbox_notifiers, nb);
+	mutex_unlock(&tegra_xhci_mbox_lock);
+}
+EXPORT_SYMBOL(tegra_xhci_unregister_mbox_notifier);

What driver would use these?

My feeling is that if you have a mailbox that is used by multiple
drivers, you should use a proper mailbox driver to operate them,
and have the drivers register with that API instead of a custom one.

+	/* Create child xhci-plat device */
+	memset(xhci_resources, 0, sizeof(xhci_resources));
+	res = platform_get_resource(to_platform_device(dev), IORESOURCE_IRQ, 0);
+	if (!res) {
+		dev_err(dev, "Missing XHCI IRQ\n");
+		ret = -ENODEV;
+		goto out;
+	}
+	xhci_resources[0].start = res->start;
+	xhci_resources[0].end = res->end;
+	xhci_resources[0].flags = res->flags;
+	xhci_resources[0].name = res->name;
+	res = platform_get_resource(to_platform_device(dev), IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "Missing XHCI registers\n");
+		ret = -ENODEV;
+		goto out;
+	}
+	xhci_resources[1].start = res->start;
+	xhci_resources[1].end = res->end;
+	xhci_resources[1].flags = res->flags;
+	xhci_resources[1].name = res->name;
+
+	xhci = platform_device_alloc("xhci-hcd", PLATFORM_DEVID_AUTO);
+	if (!xhci) {
+		dev_err(dev, "Failed to allocate XHCI host\n");
+		ret = -ENOMEM;
+		goto out;
+	}

This does not feel appropriate at all: Rather than creating a child device,
you should have a specific driver that hooks into functions exported
by the xhci core. See Documentation/driver-model/design-patterns.txt

	Arnd