Add a shutdown handler for the AMD MDB PCIe host controller that
asserts the PERST# signal via GPIO before the system powers off or
reboots. This ensures the connected PCIe endpoint is held in reset
during shutdown.

Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
---
 drivers/pci/controller/dwc/pcie-amd-mdb.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c b/drivers/pci/controller/dwc/pcie-amd-mdb.c
index 7e50e11fbffd..69d21b4727e4 100644
--- a/drivers/pci/controller/dwc/pcie-amd-mdb.c
+++ b/drivers/pci/controller/dwc/pcie-amd-mdb.c
@@ -507,6 +507,14 @@ static int amd_mdb_pcie_probe(struct platform_device *pdev)
 	return amd_mdb_add_pcie_port(pcie, pdev);
 }
 
+static void amd_mdb_pcie_shutdown(struct platform_device *pdev)
+{
+	struct amd_mdb_pcie *pcie = platform_get_drvdata(pdev);
+
+	if (pcie->perst_gpio)
+		gpiod_set_value_cansleep(pcie->perst_gpio, 1);
+}
+
 static const struct of_device_id amd_mdb_pcie_of_match[] = {
 	{
 		.compatible = "amd,versal2-mdb-host",
@@ -521,6 +529,7 @@ static struct platform_driver amd_mdb_pcie_driver = {
 		.suppress_bind_attrs = true,
 	},
 	.probe = amd_mdb_pcie_probe,
+	.shutdown = amd_mdb_pcie_shutdown,
 };
 
 builtin_platform_driver(amd_mdb_pcie_driver);
-- 
2.43.0