From 0cfbd328d60f85b0dcf66df61a3615e9a8e5d4e4 Mon Sep 17 00:00:00 2001 From: Michal Sojka Date: Wed, 24 Sep 2014 22:43:21 +0200 Subject: usb: Add LED triggers for USB activity MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Acked-by: Felipe Balbi Tested-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- drivers/usb/common/Makefile | 1 + drivers/usb/common/led.c | 57 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 58 insertions(+) create mode 100644 drivers/usb/common/led.c (limited to 'drivers/usb/common') diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile index 052c12069c24..ca2f8bd0e431 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 000000000000..df23da00a901 --- /dev/null +++ b/drivers/usb/common/led.c @@ -0,0 +1,57 @@ +/* + * LED Triggers for USB Activity + * + * Copyright 2014 Michal Sojka + * + * 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 +#include +#include +#include +#include + +#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); -- cgit v1.2.3