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    SubjectRe: [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@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:
    >>>
    >>> - 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@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;
    >>> +
    >>> + 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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