usb: Provide usb_speed_string() function

In a few places in the kernel, the code prints
a human-readable USB device speed (eg. "high speed").
This involves a switch statement sometimes wrapped
around in ({ ... }) block leading to code repetition.

To mitigate this issue, this commit introduces
usb_speed_string() function, which returns
a human-readable name of provided speed.

It also changes a few places switch was used to use
this new function.  This changes a bit the way the
speed is printed in few instances at the same time
standardising it.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 35 insertions, 0 deletions

diff --git a/drivers/usb/usb-common.c b/drivers/usb/usb-common.c
new file mode 100644
index 000000000000..d29503e954ab
--- /dev/null
+++ b/drivers/usb/usb-common.c
@@ -0,0 +1,35 @@
+/*
+ * Provides code common for host and device side USB.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2.
+ *
+ * If either host side (ie. CONFIG_USB=y) or device side USB stack
+ * (ie. CONFIG_USB_GADGET=y) is compiled in the kernel, this module is
+ * compiled-in as well.  Otherwise, if either of the two stacks is
+ * compiled as module, this file is compiled as module as well.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/usb/ch9.h>
+
+const char *usb_speed_string(enum usb_device_speed speed)
+{
+	static const char *const names[] = {
+		[USB_SPEED_UNKNOWN] = "UNKNOWN",
+		[USB_SPEED_LOW] = "low-speed",
+		[USB_SPEED_FULL] = "full-speed",
+		[USB_SPEED_HIGH] = "high-speed",
+		[USB_SPEED_WIRELESS] = "wireless",
+		[USB_SPEED_SUPER] = "super-speed",
+	};
+
+	if (speed < 0 || speed >= ARRAY_SIZE(names))
+		speed = USB_SPEED_UNKNOWN;
+	return names[speed];
+}
+EXPORT_SYMBOL_GPL(usb_speed_string);
+
+MODULE_LICENSE("GPL");