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Commit 0cfbd328 authored by Michal Sojka's avatar Michal Sojka Committed by Greg Kroah-Hartman
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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: default avatarMichal Sojka <sojka@merica.cz>
Acked-by: default avatarFelipe Balbi <balbi@ti.com>
Tested-by: default avatarFelipe Balbi <balbi@ti.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent aa923ef1

drivers/usb/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -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

drivers/usb/common/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

drivers/usb/common/led.c

0 → 100644
+57 −0
Original line number Diff line number Diff line 
/*

 * LED Triggers for USB Activity

 *

 * Copyright 2014 Michal Sojka <sojka@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);

drivers/usb/core/hcd.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

drivers/usb/gadget/udc/udc-core.c

+4 −0
Original line number Diff line number Diff line
@@ -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, req);

}

EXPORT_SYMBOL_GPL(usb_gadget_giveback_request);