libpayload: usb: Try to avoid reusing device addresses

We recently changed the USB stack to detach devices aggressively that we
don't intend to use. This alone is not really a problem, but it
exarcerbates the fact that our device detachment itself is not very
good. We destroy any local info about the device, but we don't properly
disable the offending port. The device keeps thinking that it's active,
and if we later try to reuse that device address for another device
things become confused.

The real fix would be to properly disable all ports that we don't intend
to use. Unfortunately, this isn't really possible in our current
device/hub polymorphism structure, and I don't want to hack a new
disable_port() callback into usbdev_t that really doesn't belong there.
We will only be able to fix this cleanly after we ported all root hubs
to the generic_hub interface.

Until then, an easy workaround is to just avoid reusing addresses as
long as possible. This is firmware, so the chance that we'll ever run
through 127 devices is really small in practice. Even if we ever fix the
underlying issue, it's probably a smart precaution to keep.

BRANCH=nyan,rambi
BUG=chrome-os-partner:28328
TEST=Boot from a hub that has an "unknown" device in an earlier port
than the stick you want to boot from, make sure you can still boot.

Original-Change-Id: I9b522dd8cbcd441e8c3b8781fcecd2effa0f23ee
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/197420
Original-Reviewed-by: Shawn Nematbakhsh <shawnn@chromium.org>
Original-Reviewed-by: David Hendricks <dhendrix@chromium.org>
(cherry picked from commit 28b48aa69b55a983226edf2ea616f33cd4b959e2)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: Id4c5c92e75d6b5a7e8f0ee3e396c69c4efd13176
Reviewed-on: http://review.coreboot.org/7881
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/payloads/libpayload/drivers/usb/usb.c b/payloads/libpayload/drivers/usb/usb.c
index 25bd954..53006ff 100644
--- a/payloads/libpayload/drivers/usb/usb.c
+++ b/payloads/libpayload/drivers/usb/usb.c
@@ -206,10 +206,18 @@ clear_stall (endpoint_t *ep)
 static int
 get_free_address (hci_t *controller)
 {
-	int i;
-	for (i = 1; i < 128; i++) {
-		if (controller->devices[i] == 0)
+	int i = controller->latest_address + 1;
+	for (; i != controller->latest_address; i++) {
+		if (i >= ARRAY_SIZE(controller->devices) || i < 1) {
+			usb_debug("WARNING: Device addresses for controller %#x"
+				  " wrapped around!\n", controller->reg_base);
+			i = 0;
+			continue;
+		}
+		if (controller->devices[i] == 0) {
+			controller->latest_address = i;
 			return i;
+		}
 	}
 	usb_debug ("no free address found\n");
 	return -1;		// no free address