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 0000000..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, req); } EXPORT_SYMBOL_GPL(usb_gadget_giveback_request); diff --git a/include/linux/usb.h b/include/linux/usb.h index d2465bc..447a7e2 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 -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/