summaryrefslogtreecommitdiff
path: root/include/linux/usb.h
diff options
context:
space:
mode:
authorMichal Sojka <sojka@merica.cz>2014-09-25 00:43:21 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-09-25 19:05:12 +0400
commit0cfbd328d60f85b0dcf66df61a3615e9a8e5d4e4 (patch)
treebae04eca569eecee711f27fd2e1d08e6f837ebbe /include/linux/usb.h
parentaa923ef1aa39473b7d1f413c73a3e1d19ebde65d (diff)
downloadlinux-0cfbd328d60f85b0dcf66df61a3615e9a8e5d4e4.tar.xz
usb: Add LED triggers for USB activity
With this patch, USB activity can be signaled by blinking a LED. There are two triggers, one for activity on USB host and one for USB gadget. Both triggers should work with all host/device controllers. Tested only with musb. Performace: I measured performance overheads on ARM Cortex-A8 (TI AM335x) running on 600 MHz. Duration of usb_led_activity(): - with no LED attached to the trigger: 2 ± 1 µs - with one GPIO LED attached to the trigger: 2 ± 1 µs or 8 ± 2 µs (two peaks in histogram) Duration of functions calling usb_led_activity() (with this patch applied and no LED attached to the trigger): - __usb_hcd_giveback_urb(): 10 - 25 µs - usb_gadget_giveback_request(): 2 - 6 µs Signed-off-by: Michal Sojka <sojka@merica.cz> Acked-by: Felipe Balbi <balbi@ti.com> Tested-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/usb.h')
-rw-r--r--include/linux/usb.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/usb.h b/include/linux/usb.h
index d2465bc0e73c..447a7e2fc19b 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1862,6 +1862,18 @@ extern void usb_unregister_notify(struct notifier_block *nb);
/* debugfs stuff */
extern struct dentry *usb_debug_root;
+/* LED triggers */
+enum usb_led_event {
+ USB_LED_EVENT_HOST = 0,
+ USB_LED_EVENT_GADGET = 1,
+};
+
+#ifdef CONFIG_USB_LED_TRIG
+extern void usb_led_activity(enum usb_led_event ev);
+#else
+static inline void usb_led_activity(enum usb_led_event ev) {}
+#endif
+
#endif /* __KERNEL__ */
#endif