[PATCH v3 1/3] firmware: xilinx: Add support to clear TF-A PM state

[Jay Buddhabhatti <jay.buddhabhatti@amd.com>]

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>
Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>
---
 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
-- 
2.34.1