Messages in this thread | | | Date | Wed, 28 Mar 2012 10:45:44 +1100 | From | NeilBrown <> | Subject | Re: [PATCH] LEDS-One-Shot-Timer-Trigger-implementation |
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On Tue, 27 Mar 2012 09:21:37 -0600 Shuah Khan <shuahkhan@gmail.com> wrote:
> LED infrastructure lacks support for one shot timer trigger and activation. > The current support allows for setting two timers, one for specifying how > long a state to be on, and the second for how long the state to be off. For > example, delay_on value specifies the time period an LED should stay in on > state, followed by a delay_off value that specifies how long the LED should > stay in off state. The on and off cycle repeats until the trigger gets > deactivated. There is no provision for one time activation to implement > features that require an on or off state to be held just once and then stay > in the original state forever. > > This feature will help implement vibrate functionality which requires one > shot activation of vibrate mode without a continuous vibrate on/off cycles.
In general I approve of this - thanks for your efforts.
However there are some details that need attention.
> > This patch implements the one-shot-timer trigger support by enhancing the > current led-class and ledtrig-timer drivers to support the following > use-cases: > > use-case 1: > echo one-shot-timer > /sys/class/leds/SOMELED/trigger
I don't like the name "one-shot-timer". This name describes how you expect the functionality to be used, but not what the actual difference between "timer" and "one-shot-timer" is. That difference is simply that one-shot-timer does not start an initial default blink, while "timer" does. So a name like "timer-no-default" would be a more accurate description and so should be preferred.
> echo 2000 > /sys/class/leds/SOMELED/delay_on
This command will call led_blink_set with an on time of '2000' and an off time of '0'. This will cause led_set_software_blink to turn the LED on and set no off timer. This is just as bad as starting a default blink - there is no guarantee that the LED (or vibrator) will ever be turned off.
You need to set 'delay_off' to 'forever' first.
> echo forever > /sys/class/leds/SOMELED/delay_off > > When one-shot-timer is activated in step1, unlike the timer trigger case, > one-shot-timer activate routine activates the trigger without starting > any timers. The default 1 HZ delay_on and delay_off timers won't be started > like in the case of timer trigger activation. Not starting timers ensures > that the one shot state isn't stuck if some error occurs before actual timer > periods are specified. delay_on and delay_off files get created with 0 > values. > > When delay_on value is specified in step 2, a timer gets started for delay_on > period, and delay_off stays at 0 or whatever its current value is. > > When delay_off value is specified in step 3, delay_off_store recognizes the > special forever tag and records it and returns without starting any timer. > > use-case 2: > echo one-shot-timer > /sys/class/leds/SOMELED/trigger > echo 2000 > /sys/class/leds/SOMELED/delay_off > echo forever > /sys/class/leds/SOMELED/delay_on > > When one-shot-timer is activated in step1, unlike the timer trigger case, > one-shot-timer activate routine activates the trigger without starting > any timers. The default 1 HZ delay_on and delay_off timers won't be started > like in the case of timer trigger activation. Not starting timers ensures > that the one shot state isn't stuck if some error occurs before actual timer > periods are specified. delay_on and delay_off files get created with 0 > values. > > When delay_off value is specified in step 2, a timer gets started for delay_off > period, and delay_on stays at 0 or whatever its current value is. > > When delay_on value is specified in step 3, delay_on_store recognizes the > special forever tag and records it and returns without starting any timer.
I think you should also mention here that:
- The 'forever' value is stored as 'ULONG_MAX'. Possibly a #define FOREVER ULONG_MAX in the code would be appropriate. This mapping is only used internally, not in the interface.
- The led_blink_set function - which takes two pointers to times - has been extended so that a NULL instead of a pointer means "forever".
> > >From ebc4c08c138bc8ac1ac8f4eb80f879e8e7f105d3 Mon Sep 17 00:00:00 2001 > From: Shuah Khan <shuahkhan@gmail.com> > Date: Mon, 26 Mar 2012 17:34:42 -0600 > Subject: [PATCH] LEDS-One-Shot-Timer-Trigger-implementation > > > Signed-off-by: Shuah Khan <shuahkhan@gmail.com> > --- > drivers/leds/led-class.c | 4 +- > drivers/leds/led-core.c | 26 +++++++++-- > drivers/leds/ledtrig-timer.c | 101 +++++++++++++++++++++++++++++------------ > 3 files changed, 96 insertions(+), 35 deletions(-) > > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c > index 5bff843..be7400a 100644 > --- a/drivers/leds/led-class.c > +++ b/drivers/leds/led-class.c > @@ -107,7 +107,9 @@ static void led_timer_function(unsigned long data) > > led_set_brightness(led_cdev, brightness); > > - mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay)); > + if (delay != ULONG_MAX) > + mod_timer(&led_cdev->blink_timer, > + jiffies + msecs_to_jiffies(delay)); > } > > /** > diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c > index d686004..40685f1 100644 > --- a/drivers/leds/led-core.c > +++ b/drivers/leds/led-core.c > @@ -72,17 +72,35 @@ void led_blink_set(struct led_classdev *led_cdev, > unsigned long *delay_on, > unsigned long *delay_off) > { > + unsigned long val_on; > + unsigned long val_off; > + > del_timer_sync(&led_cdev->blink_timer); > > - if (led_cdev->blink_set && > + if (delay_on && delay_off && led_cdev->blink_set && > !led_cdev->blink_set(led_cdev, delay_on, delay_off)) > return; > > + /* if delay_on is null, leave it on forever after delay_off period > + if delay_off is null, leave it off forever after delay on period */ > + if (!delay_on) > + val_on = ULONG_MAX; > + else > + val_on = *delay_on; > + > + if (!delay_off) > + val_off = ULONG_MAX; > + else > + val_off = *delay_off; > + > /* blink with 1 Hz as default if nothing specified */ > - if (!*delay_on && !*delay_off) > - *delay_on = *delay_off = 500; > + if (!val_on && !val_off) { > + val_on = val_off = 500; > + *delay_on = 500; > + *delay_off = 500; > + } > > - led_set_software_blink(led_cdev, *delay_on, *delay_off); > + led_set_software_blink(led_cdev, val_on, val_off); > } > EXPORT_SYMBOL(led_blink_set); > > diff --git a/drivers/leds/ledtrig-timer.c b/drivers/leds/ledtrig-timer.c > index 328c64c..bfda51c 100644 > --- a/drivers/leds/ledtrig-timer.c > +++ b/drivers/leds/ledtrig-timer.c > @@ -24,6 +24,9 @@ static ssize_t led_delay_on_show(struct device *dev, > { > struct led_classdev *led_cdev = dev_get_drvdata(dev); > > + if (led_cdev->blink_delay_on == ULONG_MAX) > + return sprintf(buf, "%s\n", "forever"); > +
I think return sprintf(buf, "forever\n");
if the more common usage.
Also in led_delay_off_show() below.
> return sprintf(buf, "%lu\n", led_cdev->blink_delay_on); > } > > @@ -32,17 +35,25 @@ static ssize_t led_delay_on_store(struct device *dev, > { > struct led_classdev *led_cdev = dev_get_drvdata(dev); > int ret = -EINVAL; > - char *after; > - unsigned long state = simple_strtoul(buf, &after, 10); > - size_t count = after - buf; > - > - if (isspace(*after)) > - count++; > > - if (count == size) { > - led_blink_set(led_cdev, &state, &led_cdev->blink_delay_off); > - led_cdev->blink_delay_on = state; > - ret = count; > + if (strncmp(buf, "forever", 7) == 0) { > + led_blink_set(led_cdev, NULL, &led_cdev->blink_delay_off); > + led_cdev->blink_delay_on = ULONG_MAX; > + ret = size; > + } else { > + char *after; > + unsigned long state = simple_strtoul(buf, &after, 10);
kstrtoul is currently preferred. It ensures uniform error codes.
> + size_t count = after - buf; > + > + if (isspace(*after)) > + count++; > + > + if (count == size) { > + led_blink_set(led_cdev, &state, > + &led_cdev->blink_delay_off); > + led_cdev->blink_delay_on = state; > + ret = count; > + } > } > > return ret; > @@ -53,6 +64,9 @@ static ssize_t led_delay_off_show(struct device *dev, > { > struct led_classdev *led_cdev = dev_get_drvdata(dev); > > + if (led_cdev->blink_delay_off == ULONG_MAX) > + return sprintf(buf, "%s\n", "forever"); > + > return sprintf(buf, "%lu\n", led_cdev->blink_delay_off); > } > > @@ -61,17 +75,24 @@ static ssize_t led_delay_off_store(struct device *dev, > { > struct led_classdev *led_cdev = dev_get_drvdata(dev); > int ret = -EINVAL; > - char *after; > - unsigned long state = simple_strtoul(buf, &after, 10); > - size_t count = after - buf; > > - if (isspace(*after)) > - count++; > - > - if (count == size) { > - led_blink_set(led_cdev, &led_cdev->blink_delay_on, &state); > - led_cdev->blink_delay_off = state; > - ret = count; > + if (strncmp(buf, "forever", 7) == 0) { > + led_blink_set(led_cdev, &led_cdev->blink_delay_on, NULL); > + led_cdev->blink_delay_off = ULONG_MAX; > + } else { > + char *after; > + unsigned long state = simple_strtoul(buf, &after, 10); > + size_t count = after - buf; > + > + if (isspace(*after)) > + count++; > + > + if (count == size) { > + led_blink_set(led_cdev, &led_cdev->blink_delay_on, > + &state); > + led_cdev->blink_delay_off = state; > + ret = count; > + } > } > > return ret; > @@ -80,7 +101,7 @@ static ssize_t led_delay_off_store(struct device *dev, > static DEVICE_ATTR(delay_on, 0644, led_delay_on_show, led_delay_on_store); > static DEVICE_ATTR(delay_off, 0644, led_delay_off_show, led_delay_off_store); > > -static void timer_trig_activate(struct led_classdev *led_cdev) > +static void timer_trig_activate_common(struct led_classdev *led_cdev) > { > int rc; > > @@ -91,17 +112,24 @@ static void timer_trig_activate(struct led_classdev *led_cdev) > return; > rc = device_create_file(led_cdev->dev, &dev_attr_delay_off); > if (rc) > - goto err_out_delayon; > - > - led_blink_set(led_cdev, &led_cdev->blink_delay_on, > - &led_cdev->blink_delay_off); > + device_remove_file(led_cdev->dev, &dev_attr_delay_on); > > - led_cdev->trigger_data = (void *)1; > + else > + led_cdev->trigger_data = (void *)1; > +} > > - return; > +static void timer_trig_activate_one_shot(struct led_classdev *led_cdev) > +{ > + timer_trig_activate_common(led_cdev); > +} > > -err_out_delayon: > - device_remove_file(led_cdev->dev, &dev_attr_delay_on); > +static void timer_trig_activate(struct led_classdev *led_cdev) > +{ > + timer_trig_activate_common(led_cdev); > + if (led_cdev->trigger_data) { > + led_blink_set(led_cdev, &led_cdev->blink_delay_on, > + &led_cdev->blink_delay_off); > + } > } > > static void timer_trig_deactivate(struct led_classdev *led_cdev) > @@ -121,14 +149,27 @@ static struct led_trigger timer_led_trigger = { > .deactivate = timer_trig_deactivate, > }; > > +static struct led_trigger one_shot_timer_led_trigger = { > + .name = "one-shot-timer", > + .activate = timer_trig_activate_one_shot, > + .deactivate = timer_trig_deactivate, > +}; > + > static int __init timer_trig_init(void) > { > - return led_trigger_register(&timer_led_trigger); > + int rc = 0; > + > + rc = led_trigger_register(&timer_led_trigger); > + if (!rc) > + rc = led_trigger_register(&one_shot_timer_led_trigger);
Do you need to led_trigger_unregister(&timer_led_trigger) if the registration of one_shot_timer_led_trigger fails?
> + > + return rc; > } > > static void __exit timer_trig_exit(void) > { > led_trigger_unregister(&timer_led_trigger); > + led_trigger_unregister(&one_shot_timer_led_trigger); > } > > module_init(timer_trig_init);
Thanks, NeilBrown
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