Re: [PATCH 1/4] firmware: xilinx: Add support to clear TF-A PM state

["Pandey, Radhey Shyam" <radheys@amd.com>]

On 7/23/2026 6:18 PM, Jay Buddhabhatti wrote:
> Currently, during a kexec restart, only the kernel is reloaded, while the
> TF-A specific data remain unchanged. This leads to a mismatch between the
> kernel state and the TF-A firmware state like SGI number and shutdown
> scope variable.
> 
> For example, the kernel registers an SGI number with TF-A so that TF-A can
> notify the kernel of events via that SGI. TF-A stores this SGI number in
> its internal state. After a kexec, the newly loaded kernel re-registers
> and may request a different SGI number, but the stale value programmed in
> TF-A remains, so event notifications are delivered on the old SGI and are
> missed by the new kernel. The shutdown scope variable has a similar stale
> state problem.
> 
> To resolve this, the TF_A_CLEAR_PM_STATE PM API is introduced to clear
> TF-A-specific state during kexec. On a graceful reboot, this API is
> triggered by zynqmp_firmware_shutdown(), while in a crash kernel scenario,
> it is invoked by zynqmp_firmware_probe() in the reloaded kernel.
> 
> Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@amd.com>

Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Thanks!

> ---
>   drivers/firmware/xilinx/zynqmp.c     | 48 +++++++++++++++++++++++++++-
>   include/linux/firmware/xlnx-zynqmp.h |  3 +-
>   2 files changed, 49 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
> index af838b2dc327..95ffd8f33ce9 100644
> --- a/drivers/firmware/xilinx/zynqmp.c
> +++ b/drivers/firmware/xilinx/zynqmp.c
> @@ -3,7 +3,7 @@
>    * Xilinx Zynq MPSoC Firmware layer
>    *
>    *  Copyright (C) 2014-2022 Xilinx, Inc.
> - *  Copyright (C) 2022 - 2025 Advanced Micro Devices, Inc.
> + *  Copyright (C) 2022 - 2026 Advanced Micro Devices, Inc.
>    *
>    *  Michal Simek <michal.simek@amd.com>
>    *  Davorin Mista <davorin.mista@aggios.com>
> @@ -13,6 +13,7 @@
>   
>   #include <linux/arm-smccc.h>
>   #include <linux/compiler.h>
> +#include <linux/crash_dump.h>
>   #include <linux/device.h>
>   #include <linux/init.h>
>   #include <linux/mfd/core.h>
> @@ -2065,6 +2066,42 @@ static struct attribute *zynqmp_firmware_attrs[] = {
>   
>   ATTRIBUTE_GROUPS(zynqmp_firmware);
>   
> +/**
> + * zynqmp_clear_pm_state() - Clear subsystem state
> + * @dev: Device pointer used for logging
> + *
> + * Clears PM specific data in TF-A.
> + *
> + * Return: Returns status, either success or error
> + */
> +static int zynqmp_clear_pm_state(struct device *dev)
> +{
> +	u32 pm_family_code;
> +	int ret;
> +
> +	/* Get the Family code of platform */
> +	ret = zynqmp_pm_get_family_info(&pm_family_code);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (pm_family_code != PM_ZYNQMP_FAMILY_CODE) {
> +		/* Check if the TF-A supports the TF_A_CLEAR_PM_STATE */
> +		ret = do_feature_check_call(TF_A_CLEAR_PM_STATE);
> +		if (ret >= 0 && ((ret & FIRMWARE_VERSION_MASK) >= PM_API_VERSION_1)) {
> +			/* Clear PM specific data in TF-A */
> +			ret = zynqmp_pm_invoke_fn(TF_A_CLEAR_PM_STATE, NULL, 0);
> +			if (ret)
> +				dev_err(dev,
> +					"Failed to clear TF-A specific subsystem state: %d\n", ret);
> +		} else {
> +			dev_warn(dev, "TF_A_CLEAR_PM_STATE is not supported in TF-A: %d\n", ret);
> +			ret = 0;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
>   static int zynqmp_firmware_probe(struct platform_device *pdev)
>   {
>   	struct device *dev = &pdev->dev;
> @@ -2118,6 +2155,9 @@ static int zynqmp_firmware_probe(struct platform_device *pdev)
>   	if (ret < 0)
>   		return ret;
>   
> +	if (is_kdump_kernel())
> +		zynqmp_clear_pm_state(dev);
> +
>   	/* Check trustzone version number */
>   	ret = zynqmp_pm_get_trustzone_version(&pm_tz_version);
>   	if (ret)
> @@ -2151,6 +2191,11 @@ static int zynqmp_firmware_probe(struct platform_device *pdev)
>   	return of_platform_populate(dev->of_node, NULL, NULL, dev);
>   }
>   
> +static void zynqmp_firmware_shutdown(struct platform_device *pdev)
> +{
> +	zynqmp_clear_pm_state(&pdev->dev);
> +}
> +
>   static void zynqmp_firmware_remove(struct platform_device *pdev)
>   {
>   	struct pm_api_feature_data *feature_data;
> @@ -2210,5 +2255,6 @@ static struct platform_driver zynqmp_firmware_driver = {
>   	},
>   	.probe = zynqmp_firmware_probe,
>   	.remove = zynqmp_firmware_remove,
> +	.shutdown = zynqmp_firmware_shutdown,
>   };
>   module_platform_driver(zynqmp_firmware_driver);
> diff --git a/include/linux/firmware/xlnx-zynqmp.h b/include/linux/firmware/xlnx-zynqmp.h
> index 7e27b0f7bf7e..baaa88b0b197 100644
> --- a/include/linux/firmware/xlnx-zynqmp.h
> +++ b/include/linux/firmware/xlnx-zynqmp.h
> @@ -3,7 +3,7 @@
>    * Xilinx Zynq MPSoC Firmware layer
>    *
>    *  Copyright (C) 2014-2021 Xilinx
> - *  Copyright (C) 2022 - 2025 Advanced Micro Devices, Inc.
> + *  Copyright (C) 2022 - 2026 Advanced Micro Devices, Inc.
>    *
>    *  Michal Simek <michal.simek@amd.com>
>    *  Davorin Mista <davorin.mista@aggios.com>
> @@ -66,6 +66,7 @@
>   #define FIRMWARE_VERSION_MASK		0xFFFFU
>   
>   /* ATF only commands */
> +#define TF_A_CLEAR_PM_STATE		0xa05
>   #define TF_A_PM_REGISTER_SGI		0xa04
>   #define PM_GET_TRUSTZONE_VERSION	0xa03
>   #define PM_SET_SUSPEND_MODE		0xa02