PCI: xilinx-cpm: Add support for Versal Net CPM5NC Root Port controller

The Versal Net ACAP (Adaptive Compute Acceleration Platform) devices
incorporate the Coherency and PCIe Gen5 Module, specifically the
Next-Generation Compact Module (CPM5NC).

The integrated CPM5NC block, along with the built-in bridge, can function
as a PCIe Root Port and supports the PCIe Gen5 protocol with data transfer
rates of up to 32 GT/s, and is capable of supporting up to a x16 lane-width
configuration.

Bridge errors are managed using a specific interrupt line designed for
CPM5N. The INTx interrupt support is not available.

Currently in this commit platform specific bridge errors support is not
added.

Signed-off-by: Thippeswamy Havalige <thippeswamy.havalige@amd.com>
[kwilczynski: commit log, squashed patch to fix an if-statement condition
to ensure that xilinx_cpm_pcie_init_port() does not run on the CPM5NC_HOST
variant from https://lore.kernel.org/linux-pci/20250311072402.1049990-1-thippeswamy.havalige@amd.com]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20250224155025.782179-4-thippeswamy.havalige@amd.com

Author: Thippeswamy Havalige

drivers/pci/controller/pcie-xilinx-cpm.c

@@ -84,6 +84,7 @@ enum xilinx_cpm_version {
 	CPM,
 	CPM5,
 	CPM5_HOST1,
+	CPM5NC_HOST,
 };
 
 /**
@@ -478,6 +479,9 @@ static void xilinx_cpm_pcie_init_port(struct xilinx_cpm_pcie *port)
 {
 	const struct xilinx_cpm_variant *variant = port->variant;
 
+	if (variant->version == CPM5NC_HOST)
+		return;
+
 	if (cpm_pcie_link_up(port))
 		dev_info(port->dev, "PCIe Link is UP\n");
 	else
@@ -578,18 +582,20 @@ static int xilinx_cpm_pcie_probe(struct platform_device *pdev)
 
 	port->dev = dev;
 
-	err = xilinx_cpm_pcie_init_irq_domain(port);
-	if (err)
-		return err;
+	port->variant = of_device_get_match_data(dev);
+
+	if (port->variant->version != CPM5NC_HOST) {
+		err = xilinx_cpm_pcie_init_irq_domain(port);
+		if (err)
+			return err;
+	}
 
 	bus = resource_list_first_type(&bridge->windows, IORESOURCE_BUS);
 	if (!bus) {
 		err = -ENODEV;
 		goto err_free_irq_domains;
 	}
 
-	port->variant = of_device_get_match_data(dev);
-
 	err = xilinx_cpm_pcie_parse_dt(port, bus->res);
 	if (err) {
 		dev_err(dev, "Parsing DT failed\n");
@@ -598,10 +604,12 @@ static int xilinx_cpm_pcie_probe(struct platform_device *pdev)
 
 	xilinx_cpm_pcie_init_port(port);
 
-	err = xilinx_cpm_setup_irq(port);
-	if (err) {
-		dev_err(dev, "Failed to set up interrupts\n");
-		goto err_setup_irq;
+	if (port->variant->version != CPM5NC_HOST) {
+		err = xilinx_cpm_setup_irq(port);
+		if (err) {
+			dev_err(dev, "Failed to set up interrupts\n");
+			goto err_setup_irq;
+		}
 	}
 
 	bridge->sysdata = port->cfg;
@@ -614,11 +622,13 @@ static int xilinx_cpm_pcie_probe(struct platform_device *pdev)
 	return 0;
 
 err_host_bridge:
-	xilinx_cpm_free_interrupts(port);
+	if (port->variant->version != CPM5NC_HOST)
+		xilinx_cpm_free_interrupts(port);
 err_setup_irq:
 	pci_ecam_free(port->cfg);
 err_free_irq_domains:
-	xilinx_cpm_free_irq_domains(port);
+	if (port->variant->version != CPM5NC_HOST)
+		xilinx_cpm_free_irq_domains(port);
 	return err;
 }
 
@@ -641,6 +651,10 @@ static const struct xilinx_cpm_variant cpm5_host1 = {
 	.ir_enable = XILINX_CPM_PCIE1_IR_ENABLE,
 };
 
+static const struct xilinx_cpm_variant cpm5n_host = {
+	.version = CPM5NC_HOST,
+};
+
 static const struct of_device_id xilinx_cpm_pcie_of_match[] = {
 	{
 		.compatible = "xlnx,versal-cpm-host-1.00",
@@ -654,6 +668,10 @@ static const struct of_device_id xilinx_cpm_pcie_of_match[] = {
 		.compatible = "xlnx,versal-cpm5-host1",
 		.data = &cpm5_host1,
 	},
+	{
+		.compatible = "xlnx,versal-cpm5nc-host",
+		.data = &cpm5n_host,
+	},
 	{}
 };