Re: [PATCH can-next v3 1/2] can: add tx/rx LED trigger support

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 07/31/2012 10:46 AM, Wolfgang Grandegger wrote:
> Hi Fabio,
> 
> On 07/30/2012 09:20 PM, Fabio Baltieri wrote:
>> 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 can_led_init(), can_led_exit() and
>> can_led_event() as 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: Oliver Hartkopp <socketcan@hartkopp.net>
>> Cc: Wolfgang Grandegger <wg@grandegger.com>
>> Cc: Marc Kleine-Budde <mkl@pengutronix.de>
>> Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
>> ---
>>
>> Hi all!
>>
>> This is the v3 of my CAN LED trigger patch.  It's a major refactoring of the v2
>> that was discussed about three months ago concluding with the idea that
>> implementing the oneshot triggering code in the LED framework would be a better
>> solution.
>>
>> This is the old thread for reference:
>> http://marc.info/?l=linux-can&m=133521499002898&w=2
>>
>> So, generic oneshot trigger code is now merged in mainline (see 5bb629c), and
>> these are the changes in the v3:
> 
> Nice, thanks for your patience (and not giving up).
> 
>>
>> - use the new led_trigger_blink_oneshot() function for LED triggering
>> - use kasprintf() and led_trigger_{un}register_simple for LED allocation
>> - add some usage note in the comments
>>
>> The resulting code is quite simple now and - I think - a bit less intrusive.
>> Still, I hope on some feedback from the community as I don't have that much
>> hardware to test it - this version has been tested mainly on an x86 with a
>> custom usb-can interface.
>>
>> In 2/2 there is a sample implementation for the flexcan driver, which is
>> basically unchanged from the old version.
>>
>> Any comments?
>> Fabio
>>
>>  drivers/net/can/Kconfig  | 12 ++++++
>>  drivers/net/can/Makefile |  2 +
>>  drivers/net/can/led.c    | 99 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/can/dev.h  |  8 ++++
>>  include/linux/can/led.h  | 38 +++++++++++++++++++
>>  5 files changed, 159 insertions(+)
>>  create mode 100644 drivers/net/can/led.c
>>  create mode 100644 include/linux/can/led.h
>>
>> diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
>> index bb709fd..19dec19 100644
>> --- a/drivers/net/can/Kconfig
>> +++ b/drivers/net/can/Kconfig
>> @@ -54,6 +54,18 @@ config CAN_CALC_BITTIMING
>>  	  arguments "tq", "prop_seg", "phase_seg1", "phase_seg2" and "sjw".
>>  	  If unsure, say Y.
>>  
>> +config CAN_LEDS
>> +	bool "Enable LED triggers for Netlink based drivers"
>> +	depends on CAN_DEV
>> +	depends on LEDS_CLASS
>> +	select LEDS_TRIGGERS
>> +	---help---
>> +	  This option adds two LED triggers for packet receive and transmit
>> +	  events on each supported CAN device.
>> +
>> +	  Say Y here if you are working on a system with led-class supported
>> +	  LEDs and you want to use them as canbus activity indicators.
>> +
>>  config CAN_AT91
>>  	tristate "Atmel AT91 onchip CAN controller"
>>  	depends on CAN_DEV && (ARCH_AT91SAM9263 || ARCH_AT91SAM9X5)
>> diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
>> index 938be37..24ee98b 100644
>> --- a/drivers/net/can/Makefile
>> +++ b/drivers/net/can/Makefile
>> @@ -8,6 +8,8 @@ obj-$(CONFIG_CAN_SLCAN)		+= slcan.o
>>  obj-$(CONFIG_CAN_DEV)		+= can-dev.o
>>  can-dev-y			:= dev.o
>>  
>> +can-dev-$(CONFIG_CAN_LEDS)	+= led.o
>> +
>>  obj-y				+= usb/
>>  obj-y				+= softing/
>>  
>> diff --git a/drivers/net/can/led.c b/drivers/net/can/led.c
>> new file mode 100644
>> index 0000000..68c4f30
>> --- /dev/null
>> +++ b/drivers/net/can/led.c
>> @@ -0,0 +1,99 @@
>> +/*
>> + * 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/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);
>> +
>> +/*
>> + * Register CAN LED triggers for a CAN device
>> + *
>> + * This is normally called from a driver's probe function
>> + */
>> +void can_led_init(struct net_device *netdev)
>> +{
>> +	struct can_priv *priv = netdev_priv(netdev);
>> +
>> +	priv->tx_led_trig_name = kasprintf(GFP_KERNEL, "%s-tx", netdev->name);
>> +	if (!priv->tx_led_trig_name)
>> +		goto tx_led_failed;
> 
> Just return here?
> 
>> +	priv->rx_led_trig_name = kasprintf(GFP_KERNEL, "%s-rx", netdev->name);
>> +	if (!priv->rx_led_trig_name)
>> +		goto rx_led_failed;
>> +
>> +	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);
>> +
>> +	return;
>> +
>> +rx_led_failed:
>> +	kfree(priv->tx_led_trig_name);
>> +	priv->tx_led_trig_name = NULL;
>> +tx_led_failed:
>> +	return;
> 
> In case of error the function returns silently. Is this by purpose? What
> happens if CAN_LEDS is enabled but no LEDs are assigned?

It's a bit strange, but led_trigger_register_simple() can fail silently,
too. Or better it has no return value, but does a warning printk in case
of an error.

> 
>> +}
>> +EXPORT_SYMBOL_GPL(can_led_init);
>> +
>> +/*
>> + * Unregister CAN LED triggers for a CAN device
>> + *
>> + * This is normally called from a driver's remove function
>> + */
>> +void can_led_exit(struct net_device *netdev)
>> +{
>> +	struct can_priv *priv = netdev_priv(netdev);
>> +
>> +	led_trigger_unregister_simple(priv->tx_led_trig);
>> +	led_trigger_unregister_simple(priv->rx_led_trig);
>> +
>> +	kfree(priv->tx_led_trig_name);
>> +	kfree(priv->rx_led_trig_name);
>> +}
>> +EXPORT_SYMBOL_GPL(can_led_exit);
>> diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
>> index 2b2fc34..167b04a 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;
>> +	struct led_trigger *rx_led_trig;
>> +	char *rx_led_trig_name;
>> +#endif
> 
> Do we need to store the names?

Yes, Seems, so the name is not copied:

http://lxr.free-electrons.com/source/drivers/leds/led-triggers.c#L253

Marc

-- 
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