0cfbd328d6
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>
58 lines
1.3 KiB
C
58 lines
1.3 KiB
C
/*
|
|
* 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);
|