USB/xhci: Enable remote wakeup for USB3 devices.

When the USB 3.0 hub support went in, I disabled selective suspend for
all external USB 3.0 hubs because they used a different mechanism to
enable remote wakeup.  In fact, other USB 3.0 devices that could signal
remote wakeup would have been prevented from going into suspend because
they would have stalled the SetFeature Device Remote Wakeup request.

This patch adds support for the USB 3.0 way of enabling remote wake up
(with a SetFeature Function Suspend request), and enables selective
suspend for all hubs during hub_probe.  It assumes that all USB 3.0 have
only one "function" as defined by the interface association descriptor,
which is true of all the USB 3.0 devices I've seen so far.  FIXME if
that turns out to change later.

After a device signals a remote wakeup, it is supposed to send a Device
Notification packet to the host controller, signaling which function
sent the remote wakeup.  The host can then put any other functions back
into function suspend.  Since we don't have support for function suspend
(and no devices currently support it), we'll just assume the hub
function will resume the device properly when it received the port
status change notification, and simply ignore any device notification
events from the xHCI host controller.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

2 files changed, 31 insertions, 1 deletions

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 36cbe2226a44..6b70e7fb484c 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -2141,7 +2141,7 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
         unsigned int    val, val2;
         u64             val_64;
         struct xhci_segment     *seg;
-        u32 page_size;
+        u32 page_size, temp;
         int i;
 
         page_size = xhci_readl(xhci, &xhci->op_regs->page_size);
@@ -2324,6 +2324,15 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 
         INIT_LIST_HEAD(&xhci->lpm_failed_devs);
 
+        /* Enable USB 3.0 device notifications for function remote wake, which
+         * is necessary for allowing USB 3.0 devices to do remote wakeup from
+         * U3 (device suspend).
+         */
+        temp = xhci_readl(xhci, &xhci->op_regs->dev_notification);
+        temp &= ~DEV_NOTE_MASK;
+        temp |= DEV_NOTE_FWAKE;
+        xhci_writel(xhci, temp, &xhci->op_regs->dev_notification);
+
         return 0;
 
 fail:
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index ca38483c9f56..ffe549338cec 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1237,6 +1237,24 @@ static unsigned int find_faked_portnum_from_hw_portnum(struct usb_hcd *hcd,
         return num_similar_speed_ports;
 }
 
+static void handle_device_notification(struct xhci_hcd *xhci,
+                union xhci_trb *event)
+{
+        u32 slot_id;
+
+        slot_id = TRB_TO_SLOT_ID(event->generic.field[3]);
+        if (!xhci->devs[slot_id])
+                xhci_warn(xhci, "Device Notification event for "
+                                "unused slot %u\n", slot_id);
+        else
+                xhci_dbg(xhci, "Device Notification event for slot ID %u\n",
+                                slot_id);
+        /* XXX should we kick khubd for the parent hub?  It should have send an
+         * interrupt transfer when the port started signaling resume, so there's
+         * probably no need to do so.
+         */
+}
+
 static void handle_port_status(struct xhci_hcd *xhci,
                 union xhci_trb *event)
 {
@@ -2282,6 +2300,9 @@ static int xhci_handle_event(struct xhci_hcd *xhci)
                 else
                         update_ptrs = 0;
                 break;
+        case TRB_TYPE(TRB_DEV_NOTE):
+                handle_device_notification(xhci, event);
+                break;
         default:
                 if ((le32_to_cpu(event->event_cmd.flags) & TRB_TYPE_BITMASK) >=
                     TRB_TYPE(48))