From: tim.gardner@canonical•com (Tim Gardner)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 02/19] led-triggers: create a trigger for CPU activity
Date: Mon, 30 Apr 2012 07:03:08 -0600 [thread overview]
Message-ID: <4F9E8D8C.9090704@canonical.com> (raw)
In-Reply-To: <1335771444-26361-3-git-send-email-bryan.wu@canonical.com>
On 04/30/2012 01:37 AM, Bryan Wu wrote:
> Attempting to consolidate the ARM LED code, this removes the
> custom RealView LED trigger code to turn LEDs on and off in
> response to CPU activity and replace it with a standard trigger.
>
> (bryan.wu at canonical.com:
> It introduces several syscore stubs into this trigger.
> It also provides ledtrig_cpu trigger event stub in <linux/leds.h>.
> Although it was inspired by ARM work, it can be used in other arch.)
>
> Cc: Richard Purdie <rpurdie@rpsys•net>
> Signed-off-by: Linus Walleij <linus.walleij@linaro•org>
> Signed-off-by: Bryan Wu <bryan.wu@canonical•com>
> Reviewed-by: Jamie Iles <jamie@jamieiles•com>
> Tested-by: Jochen Friedrich <jochen@scram•de>
> ---
> drivers/leds/Kconfig | 10 +++
> drivers/leds/Makefile | 1 +
> drivers/leds/ledtrig-cpu.c | 150 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/leds.h | 16 +++++
> 4 files changed, 177 insertions(+)
> create mode 100644 drivers/leds/ledtrig-cpu.c
>
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 5f12659..dbf8a4c 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -465,6 +465,16 @@ config LEDS_TRIGGER_BACKLIGHT
>
> If unsure, say N.
>
> +config LEDS_TRIGGER_CPU
> + tristate "LED CPU Trigger"
> + depends on LEDS_TRIGGERS
> + help
> + This allows LEDs to be controlled by active CPUs. This shows
> + the active CPUs across an array of LEDs so you can see which
> + CPUs are active on the system at any given moment.
> +
> + If unsure, say N.
> +
> config LEDS_TRIGGER_GPIO
> tristate "LED GPIO Trigger"
> depends on LEDS_TRIGGERS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 9475bbb..ea1efb2 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -56,4 +56,5 @@ obj-$(CONFIG_LEDS_TRIGGER_IDE_DISK) += ledtrig-ide-disk.o
> obj-$(CONFIG_LEDS_TRIGGER_HEARTBEAT) += ledtrig-heartbeat.o
> obj-$(CONFIG_LEDS_TRIGGER_BACKLIGHT) += ledtrig-backlight.o
> obj-$(CONFIG_LEDS_TRIGGER_GPIO) += ledtrig-gpio.o
> +obj-$(CONFIG_LEDS_TRIGGER_CPU) += ledtrig-cpu.o
> obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON) += ledtrig-default-on.o
> diff --git a/drivers/leds/ledtrig-cpu.c b/drivers/leds/ledtrig-cpu.c
> new file mode 100644
> index 0000000..1f752e1
> --- /dev/null
> +++ b/drivers/leds/ledtrig-cpu.c
> @@ -0,0 +1,150 @@
> +/*
> + * ledtrig-cpu.c - LED trigger based on CPU activity
> + *
> + * This LED trigger will be registered for each possible CPU and named as
> + * cpu0, cpu1, cpu2, cpu3, etc.
> + *
> + * It can be bound to any LED just like other triggers using either a
> + * board file or via sysfs interface.
> + *
> + * An API named ledtrig_cpu is exported for any user, who want to add CPU
> + * activity indication in their code
> + *
> + * Copyright 2011 Linus Walleij <linus.walleij@linaro•org>
> + * Copyright 2011 - 2012 Bryan Wu <bryan.wu@canonical•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/init.h>
> +#include <linux/slab.h>
> +#include <linux/percpu.h>
> +#include <linux/syscore_ops.h>
> +#include <linux/rwsem.h>
> +#include "leds.h"
> +
> +#define MAX_NAME_LEN 8
> +
> +static DEFINE_PER_CPU(struct led_trigger *, cpu_trig);
> +static DEFINE_PER_CPU(char [MAX_NAME_LEN], trig_name);
> +static DEFINE_PER_CPU(struct rw_semaphore, trig_lock);
Semaphores are overkill for this. I think a simple 'struct mutex' is
sufficient. Especially since there is unlikely to be much contention on
any one of the locks. mutext_init(), mutext_lock(), mutex_unlock(), etc.
> +
> +/**
> + * ledtrig_cpu - emit a CPU event as a trigger
> + * @evt: CPU event to be emitted
> + *
> + * Emit a CPU event on a CPU core, which will trigger a
> + * binded LED to turn on or turn off.
> + */
> +void ledtrig_cpu(enum cpu_led_event ledevt)
> +{
I think you still need to acquire trig_lock _before_ reading
__get_cpu_var(cpu_trig). Otherwise, acquiring the lock in
ledtrig_cpu_init() is useless.
> + struct led_trigger *trig = __get_cpu_var(cpu_trig);
> +
> + if (!trig)
> + return;
Unnecessary since led_trigger_event() also checks for (!trig).
I've attached the changes I think you should make.
rtg
--
Tim Gardner tim.gardner at canonical.com
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next prev parent reply other threads:[~2012-04-30 13:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-30 7:37 [PATCH v7 00/19] Introduce a led trigger for CPU activity and consolidate LED driver in ARM Bryan Wu
2012-04-30 7:37 ` [PATCH 01/19] led-triggers: rename *trigger to *trig for unified naming scheme Bryan Wu
2012-04-30 7:37 ` [PATCH 02/19] led-triggers: create a trigger for CPU activity Bryan Wu
2012-04-30 13:03 ` Tim Gardner [this message]
2012-05-01 11:45 ` Bryan Wu
2012-05-01 12:46 ` Tim Gardner
2012-04-30 7:37 ` [PATCH 03/19] ARM: at91: convert old leds drivers to gpio_led and led_trigger drivers Bryan Wu
2012-04-30 7:37 ` [PATCH 04/19] ARM: mach-realview and mach-versatile: retire custom LED code Bryan Wu
2012-04-30 7:37 ` [PATCH 05/19] ARM: mach-ks8695: remove leds driver, since nobody use it Bryan Wu
2012-04-30 7:37 ` [PATCH 06/19] ARM: mach-shark: retire custom LED code Bryan Wu
2012-04-30 7:37 ` [PATCH 07/19] ARM: mach-orion5x: convert custom LED code to gpio_led and LED CPU trigger Bryan Wu
2012-04-30 7:37 ` [PATCH 08/19] ARM: mach-integrator: move CM_CTRL to header file for accessing by other functions Bryan Wu
2012-04-30 7:37 ` [PATCH 09/19] ARM: mach-integrator: retire custom LED code Bryan Wu
2012-04-30 7:37 ` [PATCH 10/19] ARM: mach-clps711x: retire custom LED code of P720T machine Bryan Wu
2012-04-30 7:37 ` [PATCH 11/19] ARM: mach-ebsa110: retire custom LED code Bryan Wu
2012-04-30 7:37 ` [PATCH 12/19] ARM: mach-footbridge: " Bryan Wu
2012-04-30 7:37 ` [PATCH 13/19] char: nwflash: remove old led event code Bryan Wu
2012-04-30 7:37 ` [PATCH 14/19] ARM: mach-pxa: retire custom LED code Bryan Wu
2012-04-30 7:37 ` [PATCH 15/19] ARM: plat-samsung: remove including old leds event API header file Bryan Wu
2012-04-30 7:37 ` [PATCH 16/19] ARM: mach-pnx4008: " Bryan Wu
2012-04-30 7:37 ` [PATCH 17/19] ARM: mach-omap1: retire custom LED code Bryan Wu
2012-04-30 7:37 ` [PATCH 18/19] ARM: mach-sa1100: " Bryan Wu
2012-04-30 7:44 ` [PATCH v7 00/19] Introduce a led trigger for CPU activity and consolidate LED driver in ARM Bryan Wu
-- strict thread matches above, loose matches on Subject: below --
2012-05-01 15:01 [PATCH v9 " Bryan Wu
2012-05-01 15:01 ` [PATCH 02/19] led-triggers: create a trigger for CPU activity Bryan Wu
2012-05-01 16:05 ` Tim Gardner
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