On Wed, Jun 25, 2014 at 3:02 PM, Stephen Warren [off-list ref] wrote:

On 06/18/2014 12:16 AM, Andrew Bresticker wrote:

quoted

The Tegra XHCI controller communicates requests to the host through
a mailbox interface.  Host drivers which can handle these requests,
such as the Tegra XUSB pad controller driver and upcoming Tegra XHCI
host controller driver, can send messages and register to be notified
of incoming messages.

quoted

diff --git a/include/linux/tegra-xusb-mbox.h b/include/linux/tegra-xusb-mbox.h

quoted

+extern int tegra_xusb_mbox_register_notifier(struct tegra_xusb_mbox *mbox,
+                                          struct notifier_block *nb);
+extern void tegra_xusb_mbox_unregister_notifier(struct tegra_xusb_mbox *mbox,
+                                             struct notifier_block *nb);
+extern int tegra_xusb_mbox_send(struct tegra_xusb_mbox *mbox,
+                             enum tegra_xusb_mbox_cmd cmd, u32 data);
+extern struct tegra_xusb_mbox *
+tegra_xusb_mbox_lookup_by_phandle(struct device_node *np, const char *prop);

This seems to use a custom API. I've seen mention of a mailbox
subsystem, and I assume that has a standardized API. Should this driver
implement that instead?

All the mailbox drivers currently use a custom API, but there is
indeed a patch series floating around to create a generic mailbox
framework, though it hasn't landed in -next yet.  I can take a look at
how this driver would fit into that framework.