Hi,
On 11/7/21 9:57 AM, Ansuel Smith wrote:
From: Marek Behún <kabel@xxxxxxxxxx>
Add method trigger_offload() and member variable `offloaded` to struct
led_classdev. Add helper functions led_trigger_offload() and
led_trigger_offload_stop().
The trigger_offload() method, when implemented by the LED driver, should
be called (via led_trigger_offload() function) from trigger code wanting
to be offloaded at the moment when configuration of the trigger changes.
If the trigger is successfully offloaded, this method returns 0 and the
trigger does not have to blink the LED in software.
If the trigger with given configuration cannot be offloaded, the method
should return -EOPNOTSUPP, in which case the trigger must blink the LED
in SW.
The second argument to trigger_offload() being false means that the
offloading is being disabled. In this case the function must return 0,
errors are not permitted.
An additional config CONFIG_LEDS_OFFLOAD_TRIGGERS is added to add support
for these special trigger offload driven.
Signed-off-by: Marek Behún <kabel@xxxxxxxxxx>
Signed-off-by: Ansuel Smith <ansuelsmth@xxxxxxxxx>
---
Documentation/leds/leds-class.rst | 22 +++++++++++++++++++++
drivers/leds/led-triggers.c | 1 +
drivers/leds/trigger/Kconfig | 10 ++++++++++
include/linux/leds.h | 33 +++++++++++++++++++++++++++++++
4 files changed, 66 insertions(+)
diff --git a/Documentation/leds/leds-class.rst b/Documentation/leds/leds-class.rst
index cd155ead8703..035a738afc4a 100644
--- a/Documentation/leds/leds-class.rst
+++ b/Documentation/leds/leds-class.rst
@@ -169,6 +169,28 @@ Setting the brightness to zero with brightness_set() callback function
should completely turn off the LED and cancel the previously programmed
hardware blinking function, if any.
+Hardware offloading of LED triggers
+===================================
+
+Some LEDs can offload SW triggers to hardware (for example a LED connected to
Better to s/SW/software/ and s/HW/hardware/ throughout the documentation file
and Kconfig file(s).
+an ethernet PHY or an ethernet switch can be configured to blink on activity on
+the network, which in software is done by the netdev trigger).
+
+To do such offloading, LED driver must support the this and a deficated offload
drop: the dedicated
+trigger must be used. The LED must implement the trigger_offload() method and
How does an LED implement the trigger_offload() method?
They don't have very much logic in them AFAIK.
+the trigger code must try to call this method (via led_trigger_offload()
+function) when configuration of the trigger (trigger_data) changes.
+
+The implementation of the trigger_offload() method by the LED driver must return
+0 if the offload is successful and -EOPNOTSUPP if the requested trigger
+configuration is not supported and the trigger should be executed in software.
+If trigger_offload() returns negative value, the triggering will be done in
+software, so any active offloading must also be disabled.
+
+If the second argument (enable) to the trigger_offload() method is false, any
+active HW offloading must be deactivated. In this case errors are not permitted
+in the trigger_offload() method.
diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
index dc6816d36d06..c073e64e0a37 100644
--- a/drivers/leds/trigger/Kconfig
+++ b/drivers/leds/trigger/Kconfig
@@ -9,6 +9,16 @@ menuconfig LEDS_TRIGGERS
if LEDS_TRIGGERS
+config LEDS_OFFLOAD_TRIGGERS
+ bool "LED Offload Trigger support"
+ help
+ This option enabled offload triggers support used by leds that
LEDs
+ can be driven in HW by declaring some specific triggers.
+ A offload trigger will expose a sysfs dir to configure the
+ different blinking trigger and the available hw trigger.
Are the sysfs file values/meanings documented here?
I seem to have missed them.
+
+ If unsure, say Y.
+
thanks.
--
~Randy
