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 so...@merica.cz
---
drivers/usb/Kconfig | 10 +++
drivers/usb/common/Makefile | 1 +
drivers/usb/common/led.c | 57 +++
drivers/usb/core/hcd.c| 2 ++
drivers/usb/gadget/udc/udc-core.c | 4 +++
include/linux/usb.h | 12 +
6 files changed, 86 insertions(+)
create mode 100644 drivers/usb/common/led.c
diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
index cf1b19b..ae481c3 100644
--- a/drivers/usb/Kconfig
+++ b/drivers/usb/Kconfig
@@ -149,4 +149,14 @@ source drivers/usb/phy/Kconfig
source drivers/usb/gadget/Kconfig
+config USB_LED_TRIG
+ bool USB LED Triggers
+ depends on LEDS_CLASS USB_COMMON LEDS_TRIGGERS
+ help
+ This option adds LED triggers for USB host and/or gadget activity.
+
+ Say Y here if you are working on a system with led-class supported
+ LEDs and you want to use them as activity indicators for USB host or
+ gadget.
+
endif # USB_SUPPORT
diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile
index 052c120..ca2f8bd 100644
--- a/drivers/usb/common/Makefile
+++ b/drivers/usb/common/Makefile
@@ -4,5 +4,6 @@
obj-$(CONFIG_USB_COMMON) += usb-common.o
usb-common-y += common.o
+usb-common-$(CONFIG_USB_LED_TRIG) += led.o
obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o
diff --git a/drivers/usb/common/led.c b/drivers/usb/common/led.c
new file mode 100644
index 000..df23da0
--- /dev/null
+++ b/drivers/usb/common/led.c
@@ -0,0 +1,57 @@
+/*
+ * LED Triggers for USB Activity
+ *
+ * Copyright 2014 Michal Sojka so...@merica.cz
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include linux/module.h
+#include linux/kernel.h
+#include linux/init.h
+#include linux/leds.h
+#include linux/usb.h
+
+#define BLINK_DELAY 30
+
+static unsigned long usb_blink_delay = BLINK_DELAY;
+
+DEFINE_LED_TRIGGER(ledtrig_usb_gadget);
+DEFINE_LED_TRIGGER(ledtrig_usb_host);
+
+void usb_led_activity(enum usb_led_event ev)
+{
+ struct led_trigger *trig = NULL;
+
+ switch (ev) {
+ case USB_LED_EVENT_GADGET:
+ trig = ledtrig_usb_gadget;
+ break;
+ case USB_LED_EVENT_HOST:
+ trig = ledtrig_usb_host;
+ break;
+ }
+ /* led_trigger_blink_oneshot() handles trig == NULL gracefully */
+ led_trigger_blink_oneshot(trig, usb_blink_delay, usb_blink_delay, 0);
+}
+EXPORT_SYMBOL_GPL(usb_led_activity);
+
+
+static int __init ledtrig_usb_init(void)
+{
+ led_trigger_register_simple(usb-gadget, ledtrig_usb_gadget);
+ led_trigger_register_simple(usb-host, ledtrig_usb_host);
+ return 0;
+}
+
+static void __exit ledtrig_usb_exit(void)
+{
+ led_trigger_unregister_simple(ledtrig_usb_gadget);
+ led_trigger_unregister_simple(ledtrig_usb_host);
+}
+
+module_init(ledtrig_usb_init);
+module_exit(ledtrig_usb_exit);
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 487abcf..409cb95 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1664,6 +1664,8 @@ static void __usb_hcd_giveback_urb(struct urb *urb)
usbmon_urb_complete(hcd-self, urb, status);
usb_anchor_suspend_wakeups(anchor);
usb_unanchor_urb(urb);
+ if (likely(status == 0))
+ usb_led_activity(USB_LED_EVENT_HOST);
/* pass ownership to the completion handler */
urb-status = status;
diff --git a/drivers/usb/gadget/udc/udc-core.c
b/drivers/usb/gadget/udc/udc-core.c
index f7b3151..931b9f1 100644
--- a/drivers/usb/gadget/udc/udc-core.c
+++ b/drivers/usb/gadget/udc/udc-core.c
@@ -27,6 +27,7 @@
#include linux/usb/ch9.h
#include linux/usb/gadget.h
+#include linux/usb.h
/**
* struct usb_udc - describes one usb device controller
@@ -116,6 +117,9 @@ EXPORT_SYMBOL_GPL(usb_gadget_unmap_request);
void usb_gadget_giveback_request(struct usb_ep *ep,
struct usb_request *req)
{
+ if (likely(req-status == 0))
+ usb_led_activity(USB_LED_EVENT_GADGET);
+
req-complete(ep,
