[PATCH v7 2/3] PCI: eic7700: Add Eswin PCIe host controller driver

[zhangsenchuan@eswincomputing.com]

From: Senchuan Zhang <zhangsenchuan@eswincomputing.com>

Add driver for the Eswin EIC7700 PCIe host controller, which is based on
the DesignWare PCIe core, IP revision 5.96a. The PCIe Gen.3 controller
supports a data rate of 8 GT/s and 4 channels, support INTx and MSI
interrupts.

Signed-off-by: Yu Ning <ningyu@eswincomputing.com>
Signed-off-by: Yanghui Ou <ouyanghui@eswincomputing.com>
Signed-off-by: Senchuan Zhang <zhangsenchuan@eswincomputing.com>
---
 drivers/pci/controller/dwc/Kconfig        |  11 +
 drivers/pci/controller/dwc/Makefile       |   1 +
 drivers/pci/controller/dwc/pcie-eic7700.c | 378 ++++++++++++++++++++++
 3 files changed, 390 insertions(+)
 create mode 100644 drivers/pci/controller/dwc/pcie-eic7700.c

diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
index 519b59422b47..c837cb5947b6 100644
--- a/drivers/pci/controller/dwc/Kconfig
+++ b/drivers/pci/controller/dwc/Kconfig
@@ -93,6 +93,17 @@ config PCIE_BT1
 	  Enables support for the PCIe controller in the Baikal-T1 SoC to work
 	  in host mode. It's based on the Synopsys DWC PCIe v4.60a IP-core.
 
+config PCIE_EIC7700
+	tristate "Eswin EIC7700 PCIe controller"
+	depends on ARCH_ESWIN || COMPILE_TEST
+	depends on PCI_MSI
+	select PCIE_DW_HOST
+	help
+	  Say Y here if you want PCIe controller support for the Eswin EIC7700.
+	  The PCIe controller on EIC7700 is based on DesignWare hardware,
+	  enables support for the PCIe controller in the EIC7700 SoC to work in
+	  host mode.
+
 config PCI_IMX6
 	bool
 
diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
index 67ba59c02038..7c5a5186ea83 100644
--- a/drivers/pci/controller/dwc/Makefile
+++ b/drivers/pci/controller/dwc/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_PCIE_DW_EP) += pcie-designware-ep.o
 obj-$(CONFIG_PCIE_DW_PLAT) += pcie-designware-plat.o
 obj-$(CONFIG_PCIE_AMD_MDB) += pcie-amd-mdb.o
 obj-$(CONFIG_PCIE_BT1) += pcie-bt1.o
+obj-$(CONFIG_PCIE_EIC7700) += pcie-eic7700.o
 obj-$(CONFIG_PCI_DRA7XX) += pci-dra7xx.o
 obj-$(CONFIG_PCI_EXYNOS) += pci-exynos.o
 obj-$(CONFIG_PCIE_FU740) += pcie-fu740.o
diff --git a/drivers/pci/controller/dwc/pcie-eic7700.c b/drivers/pci/controller/dwc/pcie-eic7700.c
new file mode 100644
index 000000000000..cb7cdea6a94b
--- /dev/null
+++ b/drivers/pci/controller/dwc/pcie-eic7700.c
@@ -0,0 +1,378 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ESWIN EIC7700 PCIe root complex driver
+ *
+ * Copyright 2025, Beijing ESWIN Computing Technology Co., Ltd.
+ *
+ * Authors: Yu Ning <ningyu@eswincomputing.com>
+ *          Senchuan Zhang <zhangsenchuan@eswincomputing.com>
+ *          Yanghui Ou <ouyanghui@eswincomputing.com>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/resource.h>
+#include <linux/reset.h>
+#include <linux/types.h>
+
+#include "pcie-designware.h"
+
+/* ELBI registers */
+#define PCIEELBI_CTRL0_OFFSET		0x0
+#define PCIEELBI_STATUS0_OFFSET		0x100
+
+/* LTSSM register fields */
+#define PCIEELBI_APP_LTSSM_ENABLE	BIT(5)
+
+/* APP_HOLD_PHY_RST register fields */
+#define PCIEELBI_APP_HOLD_PHY_RST	BIT(6)
+
+/* PM_SEL_AUX_CLK register fields */
+#define PCIEELBI_PM_SEL_AUX_CLK		BIT(16)
+
+/* DEV_TYPE register fields */
+#define PCIEELBI_CTRL0_DEV_TYPE		GENMASK(3, 0)
+
+/* Vendor and device ID value */
+#define PCI_VENDOR_ID_ESWIN		0x1fe1
+#define PCI_DEVICE_ID_ESWIN		0x2030
+
+#define EIC7700_NUM_RSTS		ARRAY_SIZE(eic7700_pcie_rsts)
+
+static const char * const eic7700_pcie_rsts[] = {
+	"pwr",
+	"dbi",
+};
+
+struct eic7700_pcie_data {
+	bool no_pme_handshake;
+};
+
+struct eic7700_pcie_port {
+	struct list_head list;
+	struct reset_control *perst;
+	int num_lanes;
+};
+
+struct eic7700_pcie {
+	struct dw_pcie pci;
+	struct clk_bulk_data *clks;
+	struct reset_control_bulk_data resets[EIC7700_NUM_RSTS];
+	struct list_head ports;
+	const struct eic7700_pcie_data *data;
+	int num_clks;
+};
+
+#define to_eic7700_pcie(x) dev_get_drvdata((x)->dev)
+
+static int eic7700_pcie_start_link(struct dw_pcie *pci)
+{
+	u32 val;
+
+	/* Enable LTSSM */
+	val = readl_relaxed(pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
+	val |= PCIEELBI_APP_LTSSM_ENABLE;
+	writel_relaxed(val, pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
+
+	return 0;
+}
+
+static bool eic7700_pcie_link_up(struct dw_pcie *pci)
+{
+	u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+	u16 val = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
+
+	return val & PCI_EXP_LNKSTA_DLLLA;
+}
+
+static int eic7700_pcie_perst_reset(struct eic7700_pcie_port *port,
+				    struct eic7700_pcie *pcie)
+{
+	int ret;
+
+	ret = reset_control_assert(port->perst);
+	if (ret) {
+		dev_err(pcie->pci.dev, "Failed to assert PERST#\n");
+		return ret;
+	}
+
+	/* Ensure that PERST# has been asserted for at least 100 ms */
+	msleep(PCIE_T_PVPERL_MS);
+
+	ret = reset_control_deassert(port->perst);
+	if (ret) {
+		dev_err(pcie->pci.dev, "Failed to deassert PERST#\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int eic7700_pcie_parse_port(struct eic7700_pcie *pcie,
+				   struct device_node *node)
+{
+	struct device *dev = pcie->pci.dev;
+	struct eic7700_pcie_port *port;
+
+	port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	port->perst = of_reset_control_get_exclusive(node, "perst");
+	if (IS_ERR(port->perst)) {
+		dev_err(dev, "Failed to get PERST# reset\n");
+		return PTR_ERR(port->perst);
+	}
+
+	/*
+	 * TODO: Since the Root Port node is separated out by pcie devicetree,
+	 * the DWC core initialization code can't parse the num-lanes attribute
+	 * in the Root Port. Before entering the DWC core initialization code,
+	 * the platform driver code parses the Root Port node. The EIC7700 only
+	 * supports one Root Port node, and the num-lanes attribute is suitable
+	 * for the case of one Root Rort.
+	 */
+	if (!of_property_read_u32(node, "num-lanes", &port->num_lanes))
+		pcie->pci.num_lanes = port->num_lanes;
+
+	INIT_LIST_HEAD(&port->list);
+	list_add_tail(&port->list, &pcie->ports);
+
+	return 0;
+}
+
+static int eic7700_pcie_parse_ports(struct eic7700_pcie *pcie)
+{
+	struct eic7700_pcie_port *port, *tmp;
+	struct device *dev = pcie->pci.dev;
+	int ret;
+
+	for_each_available_child_of_node_scoped(dev->of_node, of_port) {
+		ret = eic7700_pcie_parse_port(pcie, of_port);
+		if (ret)
+			goto err_port;
+	}
+
+	return 0;
+
+err_port:
+	list_for_each_entry_safe(port, tmp, &pcie->ports, list)
+		list_del(&port->list);
+
+	return ret;
+}
+
+static int eic7700_pcie_host_init(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct eic7700_pcie *pcie = to_eic7700_pcie(pci);
+	struct eic7700_pcie_port *port;
+	u32 val;
+	int ret;
+
+	pcie->num_clks = devm_clk_bulk_get_all_enabled(pci->dev, &pcie->clks);
+	if (pcie->num_clks < 0)
+		return dev_err_probe(pci->dev, pcie->num_clks,
+				     "Failed to get pcie clocks\n");
+
+	/*
+	 * The PWR and DBI Reset signals are respectively used to reset the
+	 * PCIe controller and the DBI registers.
+	 * The PERST# signal is a reset signal that simultaneously controls the
+	 * PCIe controller, PHY, and Endpoint.
+	 * Before configuring the PHY, the PERST# signal must first be
+	 * deasserted.
+	 * The external reference clock is supplied simultaneously to the PHY
+	 * and EP. When the PHY is configurable, the entire chip already has
+	 * stable power and reference clock.
+	 * The PHY will be ready within 20ms after writing app_hold_phy_rst
+	 * register of ELBI register space.
+	 */
+	ret = reset_control_bulk_deassert(EIC7700_NUM_RSTS, pcie->resets);
+	if (ret) {
+		dev_err(pcie->pci.dev, "Failed to deassert resets\n");
+		return ret;
+	}
+
+	/* Configure Root Port type */
+	val = readl_relaxed(pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
+	val &= ~PCIEELBI_CTRL0_DEV_TYPE;
+	val |= FIELD_PREP(PCIEELBI_CTRL0_DEV_TYPE, PCI_EXP_TYPE_ROOT_PORT);
+	writel_relaxed(val, pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
+
+	list_for_each_entry(port, &pcie->ports, list) {
+		ret = eic7700_pcie_perst_reset(port, pcie);
+		if (ret)
+			goto err_perst;
+	}
+
+	/* Configure app_hold_phy_rst */
+	val = readl_relaxed(pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
+	val &= ~PCIEELBI_APP_HOLD_PHY_RST;
+	writel_relaxed(val, pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
+
+	/* The maximum waiting time for the clock switch lock is 20ms */
+	ret = readl_poll_timeout(pci->elbi_base + PCIEELBI_STATUS0_OFFSET,
+				 val, !(val & PCIEELBI_PM_SEL_AUX_CLK), 1000,
+				 20000);
+	if (ret) {
+		dev_err(pci->dev, "Timeout waiting for PM_SEL_AUX_CLK ready\n");
+		goto err_phy_init;
+	}
+
+	/*
+	 * Configure ESWIN VID:DID for Root Port as the default values are
+	 * invalid.
+	 */
+	dw_pcie_writew_dbi(pci, PCI_VENDOR_ID, PCI_VENDOR_ID_ESWIN);
+	dw_pcie_writew_dbi(pci, PCI_DEVICE_ID, PCI_DEVICE_ID_ESWIN);
+
+	return 0;
+
+err_phy_init:
+	list_for_each_entry(port, &pcie->ports, list)
+		reset_control_assert(port->perst);
+err_perst:
+	reset_control_bulk_assert(EIC7700_NUM_RSTS, pcie->resets);
+
+	return ret;
+}
+
+static void eic7700_pcie_host_deinit(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct eic7700_pcie *pcie = to_eic7700_pcie(pci);
+	struct eic7700_pcie_port *port;
+
+	list_for_each_entry(port, &pcie->ports, list)
+		reset_control_assert(port->perst);
+	reset_control_bulk_assert(EIC7700_NUM_RSTS, pcie->resets);
+	clk_bulk_disable_unprepare(pcie->num_clks, pcie->clks);
+}
+
+static const struct dw_pcie_host_ops eic7700_pcie_host_ops = {
+	.init = eic7700_pcie_host_init,
+	.deinit = eic7700_pcie_host_deinit,
+};
+
+static const struct dw_pcie_ops dw_pcie_ops = {
+	.start_link = eic7700_pcie_start_link,
+	.link_up = eic7700_pcie_link_up,
+};
+
+static int eic7700_pcie_probe(struct platform_device *pdev)
+{
+	const struct eic7700_pcie_data *data;
+	struct eic7700_pcie_port *port, *tmp;
+	struct device *dev = &pdev->dev;
+	struct eic7700_pcie *pcie;
+	struct dw_pcie *pci;
+	int ret, i;
+
+	data = of_device_get_match_data(dev);
+	if (!data)
+		return dev_err_probe(dev, -ENODATA, "OF data missing\n");
+
+	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
+	if (!pcie)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&pcie->ports);
+
+	pci = &pcie->pci;
+	pci->dev = dev;
+	pci->ops = &dw_pcie_ops;
+	pci->pp.ops = &eic7700_pcie_host_ops;
+	pcie->data = data;
+	pci->no_pme_handshake = pcie->data->no_pme_handshake;
+
+	for (i = 0; i < EIC7700_NUM_RSTS; i++)
+		pcie->resets[i].id = eic7700_pcie_rsts[i];
+
+	ret = devm_reset_control_bulk_get_exclusive(dev, EIC7700_NUM_RSTS,
+						    pcie->resets);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to get resets\n");
+
+	ret = eic7700_pcie_parse_ports(pcie);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to parse Root Port: %d\n", ret);
+
+	platform_set_drvdata(pdev, pcie);
+
+	pm_runtime_no_callbacks(dev);
+	devm_pm_runtime_enable(dev);
+	ret = pm_runtime_get_sync(dev);
+	if (ret < 0)
+		goto err_pm_runtime_put;
+
+	ret = dw_pcie_host_init(&pci->pp);
+	if (ret) {
+		dev_err(dev, "Failed to initialize host\n");
+		goto err_init;
+	}
+
+	return 0;
+
+err_init:
+	list_for_each_entry_safe(port, tmp, &pcie->ports, list) {
+		list_del(&port->list);
+		reset_control_put(port->perst);
+	}
+err_pm_runtime_put:
+	pm_runtime_put(dev);
+
+	return ret;
+}
+
+static int eic7700_pcie_suspend_noirq(struct device *dev)
+{
+	struct eic7700_pcie *pcie = dev_get_drvdata(dev);
+
+	return dw_pcie_suspend_noirq(&pcie->pci);
+}
+
+static int eic7700_pcie_resume_noirq(struct device *dev)
+{
+	struct eic7700_pcie *pcie = dev_get_drvdata(dev);
+
+	return dw_pcie_resume_noirq(&pcie->pci);
+}
+
+static const struct dev_pm_ops eic7700_pcie_pm_ops = {
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(eic7700_pcie_suspend_noirq,
+				  eic7700_pcie_resume_noirq)
+};
+
+static const struct eic7700_pcie_data eic7700_data = {
+	.no_pme_handshake = true,
+};
+
+static const struct of_device_id eic7700_pcie_of_match[] = {
+	{ .compatible = "eswin,eic7700-pcie", .data = &eic7700_data },
+	{},
+};
+
+static struct platform_driver eic7700_pcie_driver = {
+	.probe = eic7700_pcie_probe,
+	.driver = {
+		.name = "eic7700-pcie",
+		.of_match_table = eic7700_pcie_of_match,
+		.suppress_bind_attrs = true,
+		.pm = &eic7700_pcie_pm_ops,
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+builtin_platform_driver(eic7700_pcie_driver);
+
+MODULE_DESCRIPTION("Eswin EIC7700 PCIe host controller driver");
+MODULE_AUTHOR("Yu Ning <ningyu@eswincomputing.com>");
+MODULE_AUTHOR("Senchuan Zhang <zhangsenchuan@eswincomputing.com>");
+MODULE_AUTHOR("Yanghui Ou <ouyanghui@eswincomputing.com>");
+MODULE_LICENSE("GPL");
-- 
2.25.1