Date:	Tue, 31 Jul 2012 09:10:00 +0200
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	Fabio Baltieri <fabio.baltieri@...il.com>
CC:	linux-can@...r.kernel.org, linux-kernel@...r.kernel.org,
	Oliver Hartkopp <socketcan@...tkopp.net>,
	Wolfgang Grandegger <wg@...ndegger.com>
Subject: Re: [PATCH can-next v3 1/2] can: add tx/rx LED trigger support

On 07/31/2012 08:57 AM, Fabio Baltieri wrote:
> Hi Marc,
> 
> On Mon, Jul 30, 2012 at 11:17:53PM +0200, Marc Kleine-Budde wrote:
>> 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@...tkopp.net>
>>> Cc: Wolfgang Grandegger <wg@...ndegger.com>
>>> Cc: Marc Kleine-Budde <mkl@...gutronix.de>
>>> Signed-off-by: Fabio Baltieri <fabio.baltieri@...il.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:
>>>
>>> - 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
>>
>> Looks quite clean now. Can you provide a devm implementation, too?
>>
>> Marc
>>>
>>>  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@...il.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;
>>> +
>>> +	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;
>>> +}
>>> +EXPORT_SYMBOL_GPL(can_led_init);
>>
>> Can you provide a devm implementation for can_led?
> 
> Sounds reasonable, you mean like a devm_kasprintf implementation to
> remove kfree and unwinding code?

IMHO it would be sufficient if you implement the devm cleanup functions
here.

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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