1 files changed, 100 insertions, 4 deletions

diff --git a/drivers/usb/host/ehci-sysfs.c b/drivers/usb/host/ehci-sysfs.c
index 29824a98aec9..14ced00ba220 100644
--- a/drivers/usb/host/ehci-sysfs.c
+++ b/drivers/usb/host/ehci-sysfs.c
@@ -74,21 +74,117 @@ static ssize_t store_companion(struct device *dev,
 }
 static DEVICE_ATTR(companion, 0644, show_companion, store_companion);
 
+
+/*
+ * Display / Set uframe_periodic_max
+ */
+static ssize_t show_uframe_periodic_max(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct ehci_hcd		*ehci;
+	int			n;
+
+	ehci = hcd_to_ehci(bus_to_hcd(dev_get_drvdata(dev)));
+	n = scnprintf(buf, PAGE_SIZE, "%d\n", ehci->uframe_periodic_max);
+	return n;
+}
+
+
+static ssize_t store_uframe_periodic_max(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct ehci_hcd		*ehci;
+	unsigned		uframe_periodic_max;
+	unsigned		frame, uframe;
+	unsigned short		allocated_max;
+	unsigned long		flags;
+	ssize_t			ret;
+
+	ehci = hcd_to_ehci(bus_to_hcd(dev_get_drvdata(dev)));
+	if (kstrtouint(buf, 0, &uframe_periodic_max) < 0)
+		return -EINVAL;
+
+	if (uframe_periodic_max < 100 || uframe_periodic_max >= 125) {
+		ehci_info(ehci, "rejecting invalid request for "
+				"uframe_periodic_max=%u\n", uframe_periodic_max);
+		return -EINVAL;
+	}
+
+	ret = -EINVAL;
+
+	/*
+	 * lock, so that our checking does not race with possible periodic
+	 * bandwidth allocation through submitting new urbs.
+	 */
+	spin_lock_irqsave (&ehci->lock, flags);
+
+	/*
+	 * for request to decrease max periodic bandwidth, we have to check
+	 * every microframe in the schedule to see whether the decrease is
+	 * possible.
+	 */
+	if (uframe_periodic_max < ehci->uframe_periodic_max) {
+		allocated_max = 0;
+
+		for (frame = 0; frame < ehci->periodic_size; ++frame)
+			for (uframe = 0; uframe < 7; ++uframe)
+				allocated_max = max(allocated_max,
+						    periodic_usecs (ehci, frame, uframe));
+
+		if (allocated_max > uframe_periodic_max) {
+			ehci_info(ehci,
+				"cannot decrease uframe_periodic_max becase "
+				"periodic bandwidth is already allocated "
+				"(%u > %u)\n",
+				allocated_max, uframe_periodic_max);
+			goto out_unlock;
+		}
+	}
+
+	/* increasing is always ok */
+
+	ehci_info(ehci, "setting max periodic bandwidth to %u%% "
+			"(== %u usec/uframe)\n",
+			100*uframe_periodic_max/125, uframe_periodic_max);
+
+	if (uframe_periodic_max != 100)
+		ehci_warn(ehci, "max periodic bandwidth set is non-standard\n");
+
+	ehci->uframe_periodic_max = uframe_periodic_max;
+	ret = count;
+
+out_unlock:
+	spin_unlock_irqrestore (&ehci->lock, flags);
+	return ret;
+}
+static DEVICE_ATTR(uframe_periodic_max, 0644, show_uframe_periodic_max, store_uframe_periodic_max);
+
+
 static inline int create_sysfs_files(struct ehci_hcd *ehci)
 {
+	struct device	*controller = ehci_to_hcd(ehci)->self.controller;
 	int	i = 0;
 
 	/* with integrated TT there is no companion! */
 	if (!ehci_is_TDI(ehci))
-		i = device_create_file(ehci_to_hcd(ehci)->self.controller,
-				       &dev_attr_companion);
+		i = device_create_file(controller, &dev_attr_companion);
+	if (i)
+		goto out;
+
+	i = device_create_file(controller, &dev_attr_uframe_periodic_max);
+out:
 	return i;
 }
 
 static inline void remove_sysfs_files(struct ehci_hcd *ehci)
 {
+	struct device	*controller = ehci_to_hcd(ehci)->self.controller;
+
 	/* with integrated TT there is no companion! */
 	if (!ehci_is_TDI(ehci))
-		device_remove_file(ehci_to_hcd(ehci)->self.controller,
-				   &dev_attr_companion);
+		device_remove_file(controller, &dev_attr_companion);
+
+	device_remove_file(controller, &dev_attr_uframe_periodic_max);
 }