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

[Sebastian Reichel <sre@kernel.org>]

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Hi,

On Mon, Dec 07, 2020 at 11:28:29PM +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(+)
> 
> diff --git a/Documentation/devicetree/bindings/power/reset/ltc2952-poweroff.txt b/Documentation/devicetree/bindings/power/reset/ltc2952-poweroff.txt
> index cd2d7f58a..881f15a78 100644
> --- a/Documentation/devicetree/bindings/power/reset/ltc2952-poweroff.txt
> +++ b/Documentation/devicetree/bindings/power/reset/ltc2952-poweroff.txt

Please additionally Cc DT binding maintainer:

OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS
M:	Rob Herring <robh+dt@kernel.org>
L:	devicetree@vger.kernel.org

> @@ -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>;

please use tab instead of spaces

>  	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 318927938..243811541 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/of.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 (!of_property_read_u32(pdev->dev.of_node, "trigger-delay-ms",
> +				  &trigger_delay_ms)) {

please use device_property_read_u32() from <linux/property.h>.

> +		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)) {

Thanks and sorry for delayed response,

-- Sebastian

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