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>

1 files changed, 86 insertions, 0 deletions

diff --git a/drivers/net/can/led.c b/drivers/net/can/led.c
new file mode 100644
index 000000000000..c50a0d741c57
--- /dev/null
+++ b/drivers/net/can/led.c
@@ -0,0 +1,86 @@
+/*
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/netdevice.h>
+#include <linux/can/dev.h>
+
+#include <linux/can/led.h>
+
+static unsigned long led_delay = 50;
+module_param(led_delay, ulong, 0644);
+MODULE_PARM_DESC(led_delay,
+		"blink delay time for activity leds (msecs, default: 50).");
+
+/* Trigger a LED event in response to a CAN device event */
+void can_led_event(struct net_device *netdev, enum can_led_event event)
+{
+	struct can_priv *priv = netdev_priv(netdev);
+
+	switch (event) {
+	case CAN_LED_EVENT_OPEN:
+		led_trigger_event(priv->tx_led_trig, LED_FULL);
+		led_trigger_event(priv->rx_led_trig, LED_FULL);
+		break;
+	case CAN_LED_EVENT_STOP:
+		led_trigger_event(priv->tx_led_trig, LED_OFF);
+		led_trigger_event(priv->rx_led_trig, LED_OFF);
+		break;
+	case CAN_LED_EVENT_TX:
+		if (led_delay)
+			led_trigger_blink_oneshot(priv->tx_led_trig,
+						  &led_delay, &led_delay, 1);
+		break;
+	case CAN_LED_EVENT_RX:
+		if (led_delay)
+			led_trigger_blink_oneshot(priv->rx_led_trig,
+						  &led_delay, &led_delay, 1);
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(can_led_event);
+
+static void can_led_release(struct device *gendev, void *res)
+{
+	struct can_priv *priv = netdev_priv(to_net_dev(gendev));
+
+	led_trigger_unregister_simple(priv->tx_led_trig);
+	led_trigger_unregister_simple(priv->rx_led_trig);
+}
+
+/* Register CAN LED triggers for a CAN device
+ *
+ * This is normally called from a driver's probe function
+ */
+void devm_can_led_init(struct net_device *netdev)
+{
+	struct can_priv *priv = netdev_priv(netdev);
+	void *res;
+
+	res = devres_alloc(can_led_release, 0, GFP_KERNEL);
+	if (!res) {
+		netdev_err(netdev, "cannot register LED triggers\n");
+		return;
+	}
+
+	snprintf(priv->tx_led_trig_name, sizeof(priv->tx_led_trig_name),
+		 "%s-tx", netdev->name);
+	snprintf(priv->rx_led_trig_name, sizeof(priv->rx_led_trig_name),
+		 "%s-rx", netdev->name);
+
+	led_trigger_register_simple(priv->tx_led_trig_name,
+				    &priv->tx_led_trig);
+	led_trigger_register_simple(priv->rx_led_trig_name,
+				    &priv->rx_led_trig);
+
+	devres_add(&netdev->dev, res);
+}
+EXPORT_SYMBOL_GPL(devm_can_led_init);