Merge branch 'pci/controller/amd-mdb'

- Update DT binding example to separate PERST# to a Root Port stanza to
  make multiple Root Ports possible in the future (Sai Krishna Musham)

- Add driver support for Root Port PERST# (Sai Krishna Musham)

* pci/controller/amd-mdb:
  PCI: amd-mdb: Add support for PCIe RP PERST# signal handling
  dt-bindings: PCI: amd-mdb: Add example usage of reset-gpios for PCIe RP PERST#

1 files changed, 51 insertions, 1 deletions

diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c b/drivers/pci/controller/dwc/pcie-amd-mdb.c
index 9f7251a16d32..3c6e837465bb 100644
--- a/drivers/pci/controller/dwc/pcie-amd-mdb.c
+++ b/drivers/pci/controller/dwc/pcie-amd-mdb.c
@@ -18,6 +18,7 @@
 #include <linux/resource.h>
 #include <linux/types.h>
 
+#include "../../pci.h"
 #include "pcie-designware.h"
 
 #define AMD_MDB_TLP_IR_STATUS_MISC		0x4C0
@@ -56,6 +57,7 @@
  * @slcr: MDB System Level Control and Status Register (SLCR) base
  * @intx_domain: INTx IRQ domain pointer
  * @mdb_domain: MDB IRQ domain pointer
+ * @perst_gpio: GPIO descriptor for PERST# signal handling
  * @intx_irq: INTx IRQ interrupt number
  */
 struct amd_mdb_pcie {
@@ -63,6 +65,7 @@ struct amd_mdb_pcie {
 	void __iomem			*slcr;
 	struct irq_domain		*intx_domain;
 	struct irq_domain		*mdb_domain;
+	struct gpio_desc		*perst_gpio;
 	int				intx_irq;
 };
 
@@ -284,7 +287,7 @@ static int amd_mdb_pcie_init_irq_domains(struct amd_mdb_pcie *pcie,
 	struct device_node *pcie_intc_node;
 	int err;
 
-	pcie_intc_node = of_get_next_child(node, NULL);
+	pcie_intc_node = of_get_child_by_name(node, "interrupt-controller");
 	if (!pcie_intc_node) {
 		dev_err(dev, "No PCIe Intc node found\n");
 		return -ENODEV;
@@ -402,6 +405,28 @@ static int amd_mdb_setup_irq(struct amd_mdb_pcie *pcie,
 	return 0;
 }
 
+static int amd_mdb_parse_pcie_port(struct amd_mdb_pcie *pcie)
+{
+	struct device *dev = pcie->pci.dev;
+	struct device_node *pcie_port_node __maybe_unused;
+
+	/*
+	 * This platform currently supports only one Root Port, so the loop
+	 * will execute only once.
+	 * TODO: Enhance the driver to handle multiple Root Ports in the future.
+	 */
+	for_each_child_of_node_with_prefix(dev->of_node, pcie_port_node, "pcie") {
+		pcie->perst_gpio = devm_fwnode_gpiod_get(dev, of_fwnode_handle(pcie_port_node),
+							 "reset", GPIOD_OUT_HIGH, NULL);
+		if (IS_ERR(pcie->perst_gpio))
+			return dev_err_probe(dev, PTR_ERR(pcie->perst_gpio),
+					     "Failed to request reset GPIO\n");
+		return 0;
+	}
+
+	return -ENODEV;
+}
+
 static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
 				 struct platform_device *pdev)
 {
@@ -426,6 +451,12 @@ static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
 
 	pp->ops = &amd_mdb_pcie_host_ops;
 
+	if (pcie->perst_gpio) {
+		mdelay(PCIE_T_PVPERL_MS);
+		gpiod_set_value_cansleep(pcie->perst_gpio, 0);
+		mdelay(PCIE_RESET_CONFIG_WAIT_MS);
+	}
+
 	err = dw_pcie_host_init(pp);
 	if (err) {
 		dev_err(dev, "Failed to initialize host, err=%d\n", err);
@@ -444,6 +475,7 @@ static int amd_mdb_pcie_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct amd_mdb_pcie *pcie;
 	struct dw_pcie *pci;
+	int ret;
 
 	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
 	if (!pcie)
@@ -454,6 +486,24 @@ static int amd_mdb_pcie_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pcie);
 
+	ret = amd_mdb_parse_pcie_port(pcie);
+	/*
+	 * If amd_mdb_parse_pcie_port returns -ENODEV, it indicates that the
+	 * PCIe Bridge node was not found in the device tree. This is not
+	 * considered a fatal error and will trigger a fallback where the
+	 * reset GPIO is acquired directly from the PCIe Host Bridge node.
+	 */
+	if (ret) {
+		if (ret != -ENODEV)
+			return ret;
+
+		pcie->perst_gpio = devm_gpiod_get_optional(dev, "reset",
+							   GPIOD_OUT_HIGH);
+		if (IS_ERR(pcie->perst_gpio))
+			return dev_err_probe(dev, PTR_ERR(pcie->perst_gpio),
+					     "Failed to request reset GPIO\n");
+	}
+
 	return amd_mdb_add_pcie_port(pcie, pdev);
 }