[PATCH v2] power: reset: ltc2952: make trigger delay configurable

[PATCH v2] power: reset: ltc2952: make trigger delay configurable

[Marek Czerski]

Make trigger delay configurable through device tree with
trigger-delay-ms property.

Trigger delay is the time to wait before starting shutdown
sequence after trigger line assertion.
Trigger delay must take into account the OFFT time configured
with the capacitor connected to OFFT pin of the LTC2952 chip.
Basically, the higher the capacitance connected to OFFT pin,
the larger trigger delay must be.

Signed-off-by: Marek Czerski <ma.czerski@gmail.com>
---
 .../devicetree/bindings/power/reset/ltc2952-poweroff.txt  | 4 ++++
 drivers/power/reset/ltc2952-poweroff.c                    | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/Documentation/devicetree/bindings/power/reset/ltc2952-poweroff.txt b/Documentation/devicetree/bindings/power/reset/ltc2952-poweroff.txt
index cd2d7f58a9d7..38e54b3fd9f3 100644
--- a/Documentation/devicetree/bindings/power/reset/ltc2952-poweroff.txt
+++ b/Documentation/devicetree/bindings/power/reset/ltc2952-poweroff.txt
@@ -17,6 +17,9 @@ Optional properties:
 			chip's trigger line. If this property is not set, the
 			trigger function is ignored and the chip is kept alive
 			until an explicit kill signal is received
+- trigger-delay-ms	The number of milliseconds to wait after trigger line
+			assertion before executing shut down procedure.
+			The default is 2500ms.
 
 Example:
 
@@ -24,6 +27,7 @@ ltc2952 {
 	compatible = "lltc,ltc2952";
 
 	trigger-gpios = <&gpio0 1 GPIO_ACTIVE_LOW>;
+	trigger-delay-ms = <2000>;
 	watchdog-gpios = <&gpio1 2 GPIO_ACTIVE_HIGH>;
 	kill-gpios = <&gpio0 2 GPIO_ACTIVE_LOW>;
 };
diff --git a/drivers/power/reset/ltc2952-poweroff.c b/drivers/power/reset/ltc2952-poweroff.c
index 318927938b05..d1495af30081 100644
--- a/drivers/power/reset/ltc2952-poweroff.c
+++ b/drivers/power/reset/ltc2952-poweroff.c
@@ -55,6 +55,7 @@
 #include <linux/mod_devicetable.h>
 #include <linux/gpio/consumer.h>
 #include <linux/reboot.h>
+#include <linux/property.h>
 
 struct ltc2952_poweroff {
 	struct hrtimer timer_trigger;
@@ -172,10 +173,17 @@ static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
 static int ltc2952_poweroff_init(struct platform_device *pdev)
 {
 	int ret;
+	u32 trigger_delay_ms;
 	struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
 
 	ltc2952_poweroff_default(data);
 
+	if (!device_property_read_u32(&pdev->dev, "trigger-delay-ms",
+				      &trigger_delay_ms)) {
+		data->trigger_delay = ktime_set(trigger_delay_ms / MSEC_PER_SEC,
+			(trigger_delay_ms % MSEC_PER_SEC) * NSEC_PER_MSEC);
+	}
+
 	data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
 					     GPIOD_OUT_LOW);
 	if (IS_ERR(data->gpio_watchdog)) {
-- 
2.25.1

Re: [PATCH v2] power: reset: ltc2952: make trigger delay configurable

[Rob Herring]

On Wed, 03 Feb 2021 22:49:00 +0100, Marek Czerski wrote:
> Make trigger delay configurable through device tree with
> trigger-delay-ms property.
> 
> Trigger delay is the time to wait before starting shutdown
> sequence after trigger line assertion.
> Trigger delay must take into account the OFFT time configured
> with the capacitor connected to OFFT pin of the LTC2952 chip.
> Basically, the higher the capacitance connected to OFFT pin,
> the larger trigger delay must be.
> 
> Signed-off-by: Marek Czerski <ma.czerski@gmail.com>
> ---
>  .../devicetree/bindings/power/reset/ltc2952-poweroff.txt  | 4 ++++
>  drivers/power/reset/ltc2952-poweroff.c                    | 8 ++++++++
>  2 files changed, 12 insertions(+)
> 

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH v2] power: reset: ltc2952: make trigger delay configurable

[Sebastian Reichel]

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Hi,

On Wed, Feb 10, 2021 at 04:04:13PM -0600, Rob Herring wrote:
> On Wed, 03 Feb 2021 22:49:00 +0100, Marek Czerski wrote:
> > Make trigger delay configurable through device tree with
> > trigger-delay-ms property.
> > 
> > Trigger delay is the time to wait before starting shutdown
> > sequence after trigger line assertion.
> > Trigger delay must take into account the OFFT time configured
> > with the capacitor connected to OFFT pin of the LTC2952 chip.
> > Basically, the higher the capacitance connected to OFFT pin,
> > the larger trigger delay must be.
> > 
> > Signed-off-by: Marek Czerski <ma.czerski@gmail.com>
> > ---
> >  .../devicetree/bindings/power/reset/ltc2952-poweroff.txt  | 4 ++++
> >  drivers/power/reset/ltc2952-poweroff.c                    | 8 ++++++++
> >  2 files changed, 12 insertions(+)
> > 
> 
> Acked-by: Rob Herring <robh@kernel.org>

Thanks, queued.

-- Sebastian

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