linux-kernel - Re: [PATCH] rtc: zynqmp: Add shutdown callback for kexec support

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Message-ID: <2025072423552753300d57@mail.local>
Date: Fri, 25 Jul 2025 01:55:27 +0200
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: Harini T <harini.t@....com>
Cc: michal.simek@....com, linux-rtc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	git@....com
Subject: Re: [PATCH] rtc: zynqmp: Add shutdown callback for kexec support

On 24/07/2025 22:35:17+0530, Harini T wrote:
> During kexec, the hardware is not reset and any enabled interrupts can
> interfere with the new kernel's RTC initialization.

Please elaborate on the issue because alarm are supposed to stay enabled across
reboots, this is the whole point of the RTC.

> 
> The shutdown callback reuses the existing remove function to disable
> alarm interrupts and wakeup capability, putting the device in a
> quiescent state rather than completely removing it.
> 
> Signed-off-by: Harini T <harini.t@....com>
> ---
>  drivers/rtc/rtc-zynqmp.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
> index f39102b66eac..26893367f0f5 100644
> --- a/drivers/rtc/rtc-zynqmp.c
> +++ b/drivers/rtc/rtc-zynqmp.c
> @@ -383,6 +383,7 @@ MODULE_DEVICE_TABLE(of, xlnx_rtc_of_match);
>  static struct platform_driver xlnx_rtc_driver = {
>  	.probe		= xlnx_rtc_probe,
>  	.remove		= xlnx_rtc_remove,
> +	.shutdown	= xlnx_rtc_remove,
>  	.driver		= {
>  		.name	= KBUILD_MODNAME,
>  		.pm	= &xlnx_rtc_pm_ops,
> -- 
> 2.43.0
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com