can: add tx/rx LED trigger support

This patch implements the functions to add two LED triggers, named
<ifname>-tx and <ifname>-rx, to a canbus device driver.

Triggers are called from specific handlers by each CAN device driver and
can be disabled altogether with a Kconfig option.

The implementation keeps the LED on when the interface is UP and blinks
the LED on network activity at a configurable rate.

This only supports can-dev based drivers, as it uses some support field
in the can_priv structure.

Supported drivers should call devm_can_led_init() and can_led_event() as
needed.

Cleanup is handled automatically by devres, so no *_exit function is
needed.

Supported events are:
- CAN_LED_EVENT_OPEN: turn on tx/rx LEDs
- CAN_LED_EVENT_STOP: turn off tx/rx LEDs
- CAN_LED_EVENT_TX: trigger tx LED blink
- CAN_LED_EVENT_RX: trigger tx LED blink

Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

2 files changed, 50 insertions, 0 deletions

diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 2b2fc345afca..7747d9bcdc84 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -16,6 +16,7 @@
 #include <linux/can.h>
 #include <linux/can/netlink.h>
 #include <linux/can/error.h>
+#include <linux/can/led.h>
 
 /*
  * CAN mode
@@ -52,6 +53,13 @@ struct can_priv {
 
         unsigned int echo_skb_max;
         struct sk_buff **echo_skb;
+
+#ifdef CONFIG_CAN_LEDS
+        struct led_trigger *tx_led_trig;
+        char tx_led_trig_name[CAN_LED_NAME_SZ];
+        struct led_trigger *rx_led_trig;
+        char rx_led_trig_name[CAN_LED_NAME_SZ];
+#endif
 };
 
 /*
diff --git a/include/linux/can/led.h b/include/linux/can/led.h
new file mode 100644
index 000000000000..12d5549abb95
--- /dev/null
+++ b/include/linux/can/led.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2012, Fabio Baltieri <fabio.baltieri@gmail.com>
+ *
+ * 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.
+ */
+
+#ifndef CAN_LED_H
+#define CAN_LED_H
+
+#include <linux/if.h>
+#include <linux/leds.h>
+
+enum can_led_event {
+        CAN_LED_EVENT_OPEN,
+        CAN_LED_EVENT_STOP,
+        CAN_LED_EVENT_TX,
+        CAN_LED_EVENT_RX,
+};
+
+#ifdef CONFIG_CAN_LEDS
+
+/* keep space for interface name + "-tx"/"-rx" suffix and null terminator */
+#define CAN_LED_NAME_SZ (IFNAMSIZ + 4)
+
+void can_led_event(struct net_device *netdev, enum can_led_event event);
+void devm_can_led_init(struct net_device *netdev);
+
+#else
+
+static inline void can_led_event(struct net_device *netdev,
+                                 enum can_led_event event)
+{
+}
+static inline void devm_can_led_init(struct net_device *netdev)
+{
+}
+
+#endif
+
+#endif