PCI: sky1: Add PCIe host support for CIX Sky1

Add driver for the CIX Sky1 SoC PCIe Gen4 16 GT/s controller based on the
Cadence High Performance Architecture (HPA) PCIe core.

The controller supports MSI/MSI-X via GICv3, Single Virtual Channel, and
Single Function.

Signed-off-by: Hans Zhang <hans.zhang@cixtech.com>
[mani: moved the PCI ID definitions and squashed Kconfig change]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
[bhelgaas: sort Kconfig menu entry, squash
https://lore.kernel.org/r/aSBqp0cglr-Sc8na@stanley.mountain]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20251108140305.1120117-8-hans.zhang@cixtech.com

drivers/pci/controller/cadence/Kconfig

@@ -42,6 +42,21 @@ config PCIE_CADENCE_PLAT_EP
 	  endpoint mode. This PCIe controller may be embedded into many
 	  different vendors SoCs.
 
+config PCI_SKY1_HOST
+	tristate "CIX SKY1 PCIe controller (host mode)"
+	depends on OF && (ARCH_CIX || COMPILE_TEST)
+	select PCIE_CADENCE_HOST
+	select PCI_ECAM
+	help
+	  Say Y here if you want to support the CIX SKY1 PCIe platform
+	  controller in host mode. CIX SKY1 PCIe controller uses Cadence
+	  HPA (High Performance Architecture IP [Second generation of
+	  Cadence PCIe IP])
+
+	  This driver requires Cadence PCIe core infrastructure
+	  (PCIE_CADENCE_HOST) and hardware platform adaptation layer
+	  to function.
+
 config PCIE_SG2042_HOST
 	tristate "Sophgo SG2042 PCIe controller (host mode)"
 	depends on OF && (ARCH_SOPHGO || COMPILE_TEST)

drivers/pci/controller/cadence/Makefile

@@ -9,3 +9,4 @@ obj-$(CONFIG_PCIE_CADENCE_EP) += pcie-cadence-ep-mod.o
 obj-$(CONFIG_PCIE_CADENCE_PLAT) += pcie-cadence-plat.o
 obj-$(CONFIG_PCI_J721E) += pci-j721e.o
 obj-$(CONFIG_PCIE_SG2042_HOST) += pcie-sg2042.o
+obj-$(CONFIG_PCI_SKY1_HOST) += pci-sky1.o

drivers/pci/controller/cadence/pci-sky1.c

@@ -0,0 +1,238 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PCIe controller driver for CIX's sky1 SoCs
+ *
+ * Copyright 2025 Cix Technology Group Co., Ltd.
+ * Author: Hans Zhang <hans.zhang@cixtech.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/pci.h>
+#include <linux/pci-ecam.h>
+#include <linux/pci_ids.h>
+
+#include "pcie-cadence.h"
+#include "pcie-cadence-host-common.h"
+
+#define PCI_VENDOR_ID_CIX		0x1f6c
+#define PCI_DEVICE_ID_CIX_SKY1		0x0001
+
+#define STRAP_REG(n)			((n) * 0x04)
+#define STATUS_REG(n)			((n) * 0x04)
+#define LINK_TRAINING_ENABLE		BIT(0)
+#define LINK_COMPLETE			BIT(0)
+
+#define SKY1_IP_REG_BANK		0x1000
+#define SKY1_IP_CFG_CTRL_REG_BANK	0x4c00
+#define SKY1_IP_AXI_MASTER_COMMON	0xf000
+#define SKY1_AXI_SLAVE			0x9000
+#define SKY1_AXI_MASTER			0xb000
+#define SKY1_AXI_HLS_REGISTERS		0xc000
+#define SKY1_AXI_RAS_REGISTERS		0xe000
+#define SKY1_DTI_REGISTERS		0xd000
+
+#define IP_REG_I_DBG_STS_0		0x420
+
+struct sky1_pcie {
+	struct cdns_pcie *cdns_pcie;
+	struct cdns_pcie_rc *cdns_pcie_rc;
+
+	struct resource *cfg_res;
+	struct resource *msg_res;
+	struct pci_config_window *cfg;
+	void __iomem *strap_base;
+	void __iomem *status_base;
+	void __iomem *reg_base;
+	void __iomem *cfg_base;
+	void __iomem *msg_base;
+};
+
+static int sky1_pcie_resource_get(struct platform_device *pdev,
+				  struct sky1_pcie *pcie)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	void __iomem *base;
+
+	base = devm_platform_ioremap_resource_byname(pdev, "reg");
+	if (IS_ERR(base))
+		return dev_err_probe(dev, PTR_ERR(base),
+				     "unable to find \"reg\" registers\n");
+	pcie->reg_base = base;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "cfg");
+	if (!res)
+		return dev_err_probe(dev, -ENODEV, "unable to get \"cfg\" resource\n");
+	pcie->cfg_res = res;
+
+	base = devm_platform_ioremap_resource_byname(pdev, "rcsu_strap");
+	if (IS_ERR(base))
+		return dev_err_probe(dev, PTR_ERR(base),
+				     "unable to find \"rcsu_strap\" registers\n");
+	pcie->strap_base = base;
+
+	base = devm_platform_ioremap_resource_byname(pdev, "rcsu_status");
+	if (IS_ERR(base))
+		return dev_err_probe(dev, PTR_ERR(base),
+				     "unable to find \"rcsu_status\" registers\n");
+	pcie->status_base = base;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "msg");
+	if (!res)
+		return dev_err_probe(dev, -ENODEV, "unable to get \"msg\" resource\n");
+	pcie->msg_res = res;
+	pcie->msg_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(pcie->msg_base)) {
+		return dev_err_probe(dev, PTR_ERR(pcie->msg_base),
+				     "unable to ioremap msg resource\n");
+	}
+
+	return 0;
+}
+
+static int sky1_pcie_start_link(struct cdns_pcie *cdns_pcie)
+{
+	struct sky1_pcie *pcie = dev_get_drvdata(cdns_pcie->dev);
+	u32 val;
+
+	val = readl(pcie->strap_base + STRAP_REG(1));
+	val |= LINK_TRAINING_ENABLE;
+	writel(val, pcie->strap_base + STRAP_REG(1));
+
+	return 0;
+}
+
+static void sky1_pcie_stop_link(struct cdns_pcie *cdns_pcie)
+{
+	struct sky1_pcie *pcie = dev_get_drvdata(cdns_pcie->dev);
+	u32 val;
+
+	val = readl(pcie->strap_base + STRAP_REG(1));
+	val &= ~LINK_TRAINING_ENABLE;
+	writel(val, pcie->strap_base + STRAP_REG(1));
+}
+
+static bool sky1_pcie_link_up(struct cdns_pcie *cdns_pcie)
+{
+	u32 val;
+
+	val = cdns_pcie_hpa_readl(cdns_pcie, REG_BANK_IP_REG,
+				  IP_REG_I_DBG_STS_0);
+	return val & LINK_COMPLETE;
+}
+
+static const struct cdns_pcie_ops sky1_pcie_ops = {
+	.start_link = sky1_pcie_start_link,
+	.stop_link = sky1_pcie_stop_link,
+	.link_up = sky1_pcie_link_up,
+};
+
+static int sky1_pcie_probe(struct platform_device *pdev)
+{
+	struct cdns_plat_pcie_of_data *reg_off;
+	struct device *dev = &pdev->dev;
+	struct pci_host_bridge *bridge;
+	struct cdns_pcie *cdns_pcie;
+	struct resource_entry *bus;
+	struct cdns_pcie_rc *rc;
+	struct sky1_pcie *pcie;
+	int ret;
+
+	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
+	if (!pcie)
+		return -ENOMEM;
+
+	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
+	if (!bridge)
+		return -ENOMEM;
+
+	ret = sky1_pcie_resource_get(pdev, pcie);
+	if (ret < 0)
+		return ret;
+
+	bus = resource_list_first_type(&bridge->windows, IORESOURCE_BUS);
+	if (!bus)
+		return -ENODEV;
+
+	pcie->cfg = pci_ecam_create(dev, pcie->cfg_res, bus->res,
+				    &pci_generic_ecam_ops);
+	if (IS_ERR(pcie->cfg))
+		return PTR_ERR(pcie->cfg);
+
+	bridge->ops = (struct pci_ops *)&pci_generic_ecam_ops.pci_ops;
+	rc = pci_host_bridge_priv(bridge);
+	rc->ecam_supported = 1;
+	rc->cfg_base = pcie->cfg->win;
+	rc->cfg_res = &pcie->cfg->res;
+
+	cdns_pcie = &rc->pcie;
+	cdns_pcie->dev = dev;
+	cdns_pcie->ops = &sky1_pcie_ops;
+	cdns_pcie->reg_base = pcie->reg_base;
+	cdns_pcie->msg_res = pcie->msg_res;
+	cdns_pcie->is_rc = 1;
+
+	reg_off = devm_kzalloc(dev, sizeof(*reg_off), GFP_KERNEL);
+	if (!reg_off)
+		return -ENOMEM;
+
+	reg_off->ip_reg_bank_offset = SKY1_IP_REG_BANK;
+	reg_off->ip_cfg_ctrl_reg_offset = SKY1_IP_CFG_CTRL_REG_BANK;
+	reg_off->axi_mstr_common_offset = SKY1_IP_AXI_MASTER_COMMON;
+	reg_off->axi_slave_offset = SKY1_AXI_SLAVE;
+	reg_off->axi_master_offset = SKY1_AXI_MASTER;
+	reg_off->axi_hls_offset = SKY1_AXI_HLS_REGISTERS;
+	reg_off->axi_ras_offset = SKY1_AXI_RAS_REGISTERS;
+	reg_off->axi_dti_offset = SKY1_DTI_REGISTERS;
+	cdns_pcie->cdns_pcie_reg_offsets = reg_off;
+
+	pcie->cdns_pcie = cdns_pcie;
+	pcie->cdns_pcie_rc = rc;
+	pcie->cfg_base = rc->cfg_base;
+	bridge->sysdata = pcie->cfg;
+
+	rc->vendor_id = PCI_VENDOR_ID_CIX;
+	rc->device_id = PCI_DEVICE_ID_CIX_SKY1;
+	rc->no_inbound_map = 1;
+
+	dev_set_drvdata(dev, pcie);
+
+	ret = cdns_pcie_hpa_host_setup(rc);
+	if (ret < 0) {
+		pci_ecam_free(pcie->cfg);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id of_sky1_pcie_match[] = {
+	{ .compatible = "cix,sky1-pcie-host", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_sky1_pcie_match);
+
+static void sky1_pcie_remove(struct platform_device *pdev)
+{
+	struct sky1_pcie *pcie = platform_get_drvdata(pdev);
+
+	pci_ecam_free(pcie->cfg);
+}
+
+static struct platform_driver sky1_pcie_driver = {
+	.probe  = sky1_pcie_probe,
+	.remove = sky1_pcie_remove,
+	.driver = {
+		.name = "sky1-pcie",
+		.of_match_table = of_sky1_pcie_match,
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+module_platform_driver(sky1_pcie_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("PCIe controller driver for CIX's sky1 SoCs");
+MODULE_AUTHOR("Hans Zhang <hans.zhang@cixtech.com>");