PCI: qcom-ep: Add Qualcomm PCIe Endpoint controller driver

Add driver for Qualcomm PCIe Endpoint controller based on the DesignWare
core with added Qualcomm-specific wrapper around the core. The driver
support is very basic such that it supports only enumeration, PCIe
read/write, and MSI. There is no ASPM and PM support for now but these will
be added later.

The driver is capable of using the PERST# and WAKE# side-band GPIOs for
operation and written on top of the DWC PCI framework.

[bhelgaas: wrap a few long lines]
Co-developed-by: Siddartha Mohanadoss <[e-mail]>
[mani: restructured the driver and fixed several bugs for upstream]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Siddartha Mohanadoss <[e-mail]>
Signed-off-by: Manivannan Sadhasivam <[e-mail]>
Signed-off-by: Lorenzo Pieralisi <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>

drivers/pci/controller/dwc/Kconfig

···
 	  PCIe controller uses the DesignWare core plus Qualcomm-specific
 	  hardware wrappers.
 
+config PCIE_QCOM_EP
+	tristate "Qualcomm PCIe controller - Endpoint mode"
+	depends on OF && (ARCH_QCOM || COMPILE_TEST)
+	depends on PCI_ENDPOINT
+	select PCIE_DW_EP
+	help
+	  Say Y here to enable support for the PCIe controllers on Qualcomm SoCs
+	  to work in endpoint mode. The PCIe controller uses the DesignWare core
+	  plus Qualcomm-specific hardware wrappers.
+
 config PCIE_ARMADA_8K
 	bool "Marvell Armada-8K PCIe controller"
 	depends on ARCH_MVEBU || COMPILE_TEST

drivers/pci/controller/dwc/Makefile

···
 obj-$(CONFIG_PCI_LAYERSCAPE) += pci-layerscape.o
 obj-$(CONFIG_PCI_LAYERSCAPE_EP) += pci-layerscape-ep.o
 obj-$(CONFIG_PCIE_QCOM) += pcie-qcom.o
+obj-$(CONFIG_PCIE_QCOM_EP) += pcie-qcom-ep.o
 obj-$(CONFIG_PCIE_ARMADA_8K) += pcie-armada8k.o
 obj-$(CONFIG_PCIE_ARTPEC6) += pcie-artpec6.o
 obj-$(CONFIG_PCIE_ROCKCHIP_DW_HOST) += pcie-dw-rockchip.o

drivers/pci/controller/dwc/pcie-designware-ep.c

···
 	for (func_no = 0; func_no < funcs; func_no++)
 		__dw_pcie_ep_reset_bar(pci, func_no, bar, 0);
 }
+EXPORT_SYMBOL_GPL(dw_pcie_ep_reset_bar);
 
 static u8 __dw_pcie_ep_find_next_cap(struct dw_pcie_ep *ep, u8 func_no,
 		u8 cap_ptr, u8 cap)
···
 
 	return -EINVAL;
 }
+EXPORT_SYMBOL_GPL(dw_pcie_ep_raise_legacy_irq);
 
 int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
 			     u8 interrupt_num)
···
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(dw_pcie_ep_raise_msi_irq);
 
 int dw_pcie_ep_raise_msix_irq_doorbell(struct dw_pcie_ep *ep, u8 func_no,
 				       u16 interrupt_num)

drivers/pci/controller/dwc/pcie-qcom-ep.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Qualcomm PCIe Endpoint controller driver
+ *
+ * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ * Author: Siddartha Mohanadoss <[e-mail]
+ *
+ * Copyright (c) 2021, Linaro Ltd.
+ * Author: Manivannan Sadhasivam <[e-mail]
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/mfd/syscon.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+
+#include "pcie-designware.h"
+
+/* PARF registers */
+#define PARF_SYS_CTRL				0x00
+#define PARF_DB_CTRL				0x10
+#define PARF_PM_CTRL				0x20
+#define PARF_MHI_BASE_ADDR_LOWER		0x178
+#define PARF_MHI_BASE_ADDR_UPPER		0x17c
+#define PARF_DEBUG_INT_EN			0x190
+#define PARF_AXI_MSTR_RD_HALT_NO_WRITES		0x1a4
+#define PARF_AXI_MSTR_WR_ADDR_HALT		0x1a8
+#define PARF_Q2A_FLUSH				0x1ac
+#define PARF_LTSSM				0x1b0
+#define PARF_CFG_BITS				0x210
+#define PARF_INT_ALL_STATUS			0x224
+#define PARF_INT_ALL_CLEAR			0x228
+#define PARF_INT_ALL_MASK			0x22c
+#define PARF_SLV_ADDR_MSB_CTRL			0x2c0
+#define PARF_DBI_BASE_ADDR			0x350
+#define PARF_DBI_BASE_ADDR_HI			0x354
+#define PARF_SLV_ADDR_SPACE_SIZE		0x358
+#define PARF_SLV_ADDR_SPACE_SIZE_HI		0x35c
+#define PARF_ATU_BASE_ADDR			0x634
+#define PARF_ATU_BASE_ADDR_HI			0x638
+#define PARF_SRIS_MODE				0x644
+#define PARF_DEVICE_TYPE			0x1000
+#define PARF_BDF_TO_SID_CFG			0x2c00
+
+/* PARF_INT_ALL_{STATUS/CLEAR/MASK} register fields */
+#define PARF_INT_ALL_LINK_DOWN			BIT(1)
+#define PARF_INT_ALL_BME			BIT(2)
+#define PARF_INT_ALL_PM_TURNOFF			BIT(3)
+#define PARF_INT_ALL_DEBUG			BIT(4)
+#define PARF_INT_ALL_LTR			BIT(5)
+#define PARF_INT_ALL_MHI_Q6			BIT(6)
+#define PARF_INT_ALL_MHI_A7			BIT(7)
+#define PARF_INT_ALL_DSTATE_CHANGE		BIT(8)
+#define PARF_INT_ALL_L1SUB_TIMEOUT		BIT(9)
+#define PARF_INT_ALL_MMIO_WRITE			BIT(10)
+#define PARF_INT_ALL_CFG_WRITE			BIT(11)
+#define PARF_INT_ALL_BRIDGE_FLUSH_N		BIT(12)
+#define PARF_INT_ALL_LINK_UP			BIT(13)
+#define PARF_INT_ALL_AER_LEGACY			BIT(14)
+#define PARF_INT_ALL_PLS_ERR			BIT(15)
+#define PARF_INT_ALL_PME_LEGACY			BIT(16)
+#define PARF_INT_ALL_PLS_PME			BIT(17)
+
+/* PARF_BDF_TO_SID_CFG register fields */
+#define PARF_BDF_TO_SID_BYPASS			BIT(0)
+
+/* PARF_DEBUG_INT_EN register fields */
+#define PARF_DEBUG_INT_PM_DSTATE_CHANGE		BIT(1)
+#define PARF_DEBUG_INT_CFG_BUS_MASTER_EN	BIT(2)
+#define PARF_DEBUG_INT_RADM_PM_TURNOFF		BIT(3)
+
+/* PARF_DEVICE_TYPE register fields */
+#define PARF_DEVICE_TYPE_EP			0x0
+
+/* PARF_PM_CTRL register fields */
+#define PARF_PM_CTRL_REQ_EXIT_L1		BIT(1)
+#define PARF_PM_CTRL_READY_ENTR_L23		BIT(2)
+#define PARF_PM_CTRL_REQ_NOT_ENTR_L1		BIT(5)
+
+/* PARF_AXI_MSTR_RD_HALT_NO_WRITES register fields */
+#define PARF_AXI_MSTR_RD_HALT_NO_WRITE_EN	BIT(0)
+
+/* PARF_AXI_MSTR_WR_ADDR_HALT register fields */
+#define PARF_AXI_MSTR_WR_ADDR_HALT_EN		BIT(31)
+
+/* PARF_Q2A_FLUSH register fields */
+#define PARF_Q2A_FLUSH_EN			BIT(16)
+
+/* PARF_SYS_CTRL register fields */
+#define PARF_SYS_CTRL_AUX_PWR_DET		BIT(4)
+#define PARF_SYS_CTRL_CORE_CLK_CGC_DIS		BIT(6)
+#define PARF_SYS_CTRL_SLV_DBI_WAKE_DISABLE	BIT(11)
+
+/* PARF_DB_CTRL register fields */
+#define PARF_DB_CTRL_INSR_DBNCR_BLOCK		BIT(0)
+#define PARF_DB_CTRL_RMVL_DBNCR_BLOCK		BIT(1)
+#define PARF_DB_CTRL_DBI_WKP_BLOCK		BIT(4)
+#define PARF_DB_CTRL_SLV_WKP_BLOCK		BIT(5)
+#define PARF_DB_CTRL_MST_WKP_BLOCK		BIT(6)
+
+/* PARF_CFG_BITS register fields */
+#define PARF_CFG_BITS_REQ_EXIT_L1SS_MSI_LTR_EN	BIT(1)
+
+/* ELBI registers */
+#define ELBI_SYS_STTS				0x08
+
+/* DBI registers */
+#define DBI_CON_STATUS				0x44
+
+/* DBI register fields */
+#define DBI_CON_STATUS_POWER_STATE_MASK		GENMASK(1, 0)
+
+#define XMLH_LINK_UP				0x400
+#define CORE_RESET_TIME_US_MIN			1000
+#define CORE_RESET_TIME_US_MAX			1005
+#define WAKE_DELAY_US				2000 /* 2 ms */
+
+#define to_pcie_ep(x)				dev_get_drvdata((x)->dev)
+
+enum qcom_pcie_ep_link_status {
+	QCOM_PCIE_EP_LINK_DISABLED,
+	QCOM_PCIE_EP_LINK_ENABLED,
+	QCOM_PCIE_EP_LINK_UP,
+	QCOM_PCIE_EP_LINK_DOWN,
+};
+
+static struct clk_bulk_data qcom_pcie_ep_clks[] = {
+	{ .id = "cfg" },
+	{ .id = "aux" },
+	{ .id = "bus_master" },
+	{ .id = "bus_slave" },
+	{ .id = "ref" },
+	{ .id = "sleep" },
+	{ .id = "slave_q2a" },
+};
+
+struct qcom_pcie_ep {
+	struct dw_pcie pci;
+
+	void __iomem *parf;
+	void __iomem *elbi;
+	struct regmap *perst_map;
+	struct resource *mmio_res;
+
+	struct reset_control *core_reset;
+	struct gpio_desc *reset;
+	struct gpio_desc *wake;
+	struct phy *phy;
+
+	u32 perst_en;
+	u32 perst_sep_en;
+
+	enum qcom_pcie_ep_link_status link_status;
+	int global_irq;
+	int perst_irq;
+};
+
+static int qcom_pcie_ep_core_reset(struct qcom_pcie_ep *pcie_ep)
+{
+	struct dw_pcie *pci = &pcie_ep->pci;
+	struct device *dev = pci->dev;
+	int ret;
+
+	ret = reset_control_assert(pcie_ep->core_reset);
+	if (ret) {
+		dev_err(dev, "Cannot assert core reset\n");
+		return ret;
+	}
+
+	usleep_range(CORE_RESET_TIME_US_MIN, CORE_RESET_TIME_US_MAX);
+
+	ret = reset_control_deassert(pcie_ep->core_reset);
+	if (ret) {
+		dev_err(dev, "Cannot de-assert core reset\n");
+		return ret;
+	}
+
+	usleep_range(CORE_RESET_TIME_US_MIN, CORE_RESET_TIME_US_MAX);
+
+	return 0;
+}
+
+/*
+ * Delatch PERST_EN and PERST_SEPARATION_ENABLE with TCSR to avoid
+ * device reset during host reboot and hibernation. The driver is
+ * expected to handle this situation.
+ */
+static void qcom_pcie_ep_configure_tcsr(struct qcom_pcie_ep *pcie_ep)
+{
+	regmap_write(pcie_ep->perst_map, pcie_ep->perst_en, 0);
+	regmap_write(pcie_ep->perst_map, pcie_ep->perst_sep_en, 0);
+}
+
+static int qcom_pcie_dw_link_up(struct dw_pcie *pci)
+{
+	struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
+	u32 reg;
+
+	reg = readl_relaxed(pcie_ep->elbi + ELBI_SYS_STTS);
+
+	return reg & XMLH_LINK_UP;
+}
+
+static int qcom_pcie_dw_start_link(struct dw_pcie *pci)
+{
+	struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
+
+	enable_irq(pcie_ep->perst_irq);
+
+	return 0;
+}
+
+static void qcom_pcie_dw_stop_link(struct dw_pcie *pci)
+{
+	struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
+
+	disable_irq(pcie_ep->perst_irq);
+}
+
+static int qcom_pcie_perst_deassert(struct dw_pcie *pci)
+{
+	struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
+	struct device *dev = pci->dev;
+	u32 val, offset;
+	int ret;
+
+	ret = clk_bulk_prepare_enable(ARRAY_SIZE(qcom_pcie_ep_clks),
+				      qcom_pcie_ep_clks);
+	if (ret)
+		return ret;
+
+	ret = qcom_pcie_ep_core_reset(pcie_ep);
+	if (ret)
+		goto err_disable_clk;
+
+	ret = phy_init(pcie_ep->phy);
+	if (ret)
+		goto err_disable_clk;
+
+	ret = phy_power_on(pcie_ep->phy);
+	if (ret)
+		goto err_phy_exit;
+
+	/* Assert WAKE# to RC to indicate device is ready */
+	gpiod_set_value_cansleep(pcie_ep->wake, 1);
+	usleep_range(WAKE_DELAY_US, WAKE_DELAY_US + 500);
+	gpiod_set_value_cansleep(pcie_ep->wake, 0);
+
+	qcom_pcie_ep_configure_tcsr(pcie_ep);
+
+	/* Disable BDF to SID mapping */
+	val = readl_relaxed(pcie_ep->parf + PARF_BDF_TO_SID_CFG);
+	val |= PARF_BDF_TO_SID_BYPASS;
+	writel_relaxed(val, pcie_ep->parf + PARF_BDF_TO_SID_CFG);
+
+	/* Enable debug IRQ */
+	val = readl_relaxed(pcie_ep->parf + PARF_DEBUG_INT_EN);
+	val |= PARF_DEBUG_INT_RADM_PM_TURNOFF |
+	       PARF_DEBUG_INT_CFG_BUS_MASTER_EN |
+	       PARF_DEBUG_INT_PM_DSTATE_CHANGE;
+	writel_relaxed(val, pcie_ep->parf + PARF_DEBUG_INT_EN);
+
+	/* Configure PCIe to endpoint mode */
+	writel_relaxed(PARF_DEVICE_TYPE_EP, pcie_ep->parf + PARF_DEVICE_TYPE);
+
+	/* Allow entering L1 state */
+	val = readl_relaxed(pcie_ep->parf + PARF_PM_CTRL);
+	val &= ~PARF_PM_CTRL_REQ_NOT_ENTR_L1;
+	writel_relaxed(val, pcie_ep->parf + PARF_PM_CTRL);
+
+	/* Read halts write */
+	val = readl_relaxed(pcie_ep->parf + PARF_AXI_MSTR_RD_HALT_NO_WRITES);
+	val &= ~PARF_AXI_MSTR_RD_HALT_NO_WRITE_EN;
+	writel_relaxed(val, pcie_ep->parf + PARF_AXI_MSTR_RD_HALT_NO_WRITES);
+
+	/* Write after write halt */
+	val = readl_relaxed(pcie_ep->parf + PARF_AXI_MSTR_WR_ADDR_HALT);
+	val |= PARF_AXI_MSTR_WR_ADDR_HALT_EN;
+	writel_relaxed(val, pcie_ep->parf + PARF_AXI_MSTR_WR_ADDR_HALT);
+
+	/* Q2A flush disable */
+	val = readl_relaxed(pcie_ep->parf + PARF_Q2A_FLUSH);
+	val &= ~PARF_Q2A_FLUSH_EN;
+	writel_relaxed(val, pcie_ep->parf + PARF_Q2A_FLUSH);
+
+	/* Disable DBI Wakeup, core clock CGC and enable AUX power */
+	val = readl_relaxed(pcie_ep->parf + PARF_SYS_CTRL);
+	val |= PARF_SYS_CTRL_SLV_DBI_WAKE_DISABLE |
+	       PARF_SYS_CTRL_CORE_CLK_CGC_DIS |
+	       PARF_SYS_CTRL_AUX_PWR_DET;
+	writel_relaxed(val, pcie_ep->parf + PARF_SYS_CTRL);
+
+	/* Disable the debouncers */
+	val = readl_relaxed(pcie_ep->parf + PARF_DB_CTRL);
+	val |= PARF_DB_CTRL_INSR_DBNCR_BLOCK | PARF_DB_CTRL_RMVL_DBNCR_BLOCK |
+	       PARF_DB_CTRL_DBI_WKP_BLOCK | PARF_DB_CTRL_SLV_WKP_BLOCK |
+	       PARF_DB_CTRL_MST_WKP_BLOCK;
+	writel_relaxed(val, pcie_ep->parf + PARF_DB_CTRL);
+
+	/* Request to exit from L1SS for MSI and LTR MSG */
+	val = readl_relaxed(pcie_ep->parf + PARF_CFG_BITS);
+	val |= PARF_CFG_BITS_REQ_EXIT_L1SS_MSI_LTR_EN;
+	writel_relaxed(val, pcie_ep->parf + PARF_CFG_BITS);
+
+	dw_pcie_dbi_ro_wr_en(pci);
+
+	/* Set the L0s Exit Latency to 2us-4us = 0x6 */
+	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+	val = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
+	val &= ~PCI_EXP_LNKCAP_L0SEL;
+	val |= FIELD_PREP(PCI_EXP_LNKCAP_L0SEL, 0x6);
+	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, val);
+
+	/* Set the L1 Exit Latency to be 32us-64 us = 0x6 */
+	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+	val = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
+	val &= ~PCI_EXP_LNKCAP_L1EL;
+	val |= FIELD_PREP(PCI_EXP_LNKCAP_L1EL, 0x6);
+	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, val);
+
+	dw_pcie_dbi_ro_wr_dis(pci);
+
+	writel_relaxed(0, pcie_ep->parf + PARF_INT_ALL_MASK);
+	val = PARF_INT_ALL_LINK_DOWN | PARF_INT_ALL_BME |
+	      PARF_INT_ALL_PM_TURNOFF | PARF_INT_ALL_DSTATE_CHANGE |
+	      PARF_INT_ALL_LINK_UP;
+	writel_relaxed(val, pcie_ep->parf + PARF_INT_ALL_MASK);
+
+	ret = dw_pcie_ep_init_complete(&pcie_ep->pci.ep);
+	if (ret) {
+		dev_err(dev, "Failed to complete initialization: %d\n", ret);
+		goto err_phy_power_off;
+	}
+
+	/*
+	 * The physical address of the MMIO region which is exposed as the BAR
+	 * should be written to MHI BASE registers.
+	 */
+	writel_relaxed(pcie_ep->mmio_res->start,
+		       pcie_ep->parf + PARF_MHI_BASE_ADDR_LOWER);
+	writel_relaxed(0, pcie_ep->parf + PARF_MHI_BASE_ADDR_UPPER);
+
+	dw_pcie_ep_init_notify(&pcie_ep->pci.ep);
+
+	/* Enable LTSSM */
+	val = readl_relaxed(pcie_ep->parf + PARF_LTSSM);
+	val |= BIT(8);
+	writel_relaxed(val, pcie_ep->parf + PARF_LTSSM);
+
+	return 0;
+
+err_phy_power_off:
+	phy_power_off(pcie_ep->phy);
+err_phy_exit:
+	phy_exit(pcie_ep->phy);
+err_disable_clk:
+	clk_bulk_disable_unprepare(ARRAY_SIZE(qcom_pcie_ep_clks),
+				   qcom_pcie_ep_clks);
+
+	return ret;
+}
+
+static void qcom_pcie_perst_assert(struct dw_pcie *pci)
+{
+	struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
+	struct device *dev = pci->dev;
+
+	if (pcie_ep->link_status == QCOM_PCIE_EP_LINK_DISABLED) {
+		dev_dbg(dev, "Link is already disabled\n");
+		return;
+	}
+
+	phy_power_off(pcie_ep->phy);
+	phy_exit(pcie_ep->phy);
+	clk_bulk_disable_unprepare(ARRAY_SIZE(qcom_pcie_ep_clks),
+				   qcom_pcie_ep_clks);
+	pcie_ep->link_status = QCOM_PCIE_EP_LINK_DISABLED;
+}
+
+/* Common DWC controller ops */
+static const struct dw_pcie_ops pci_ops = {
+	.link_up = qcom_pcie_dw_link_up,
+	.start_link = qcom_pcie_dw_start_link,
+	.stop_link = qcom_pcie_dw_stop_link,
+};
+
+static int qcom_pcie_ep_get_io_resources(struct platform_device *pdev,
+					 struct qcom_pcie_ep *pcie_ep)
+{
+	struct device *dev = &pdev->dev;
+	struct dw_pcie *pci = &pcie_ep->pci;
+	struct device_node *syscon;
+	struct resource *res;
+	int ret;
+
+	pcie_ep->parf = devm_platform_ioremap_resource_byname(pdev, "parf");
+	if (IS_ERR(pcie_ep->parf))
+		return PTR_ERR(pcie_ep->parf);
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dbi");
+	pci->dbi_base = devm_pci_remap_cfg_resource(dev, res);
+	if (IS_ERR(pci->dbi_base))
+		return PTR_ERR(pci->dbi_base);
+	pci->dbi_base2 = pci->dbi_base;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "elbi");
+	pcie_ep->elbi = devm_pci_remap_cfg_resource(dev, res);
+	if (IS_ERR(pcie_ep->elbi))
+		return PTR_ERR(pcie_ep->elbi);
+
+	pcie_ep->mmio_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+							 "mmio");
+
+	syscon = of_parse_phandle(dev->of_node, "qcom,perst-regs", 0);
+	if (!syscon) {
+		dev_err(dev, "Failed to parse qcom,perst-regs\n");
+		return -EINVAL;
+	}
+
+	pcie_ep->perst_map = syscon_node_to_regmap(syscon);
+	of_node_put(syscon);
+	if (IS_ERR(pcie_ep->perst_map))
+		return PTR_ERR(pcie_ep->perst_map);
+
+	ret = of_property_read_u32_index(dev->of_node, "qcom,perst-regs",
+					 1, &pcie_ep->perst_en);
+	if (ret < 0) {
+		dev_err(dev, "No Perst Enable offset in syscon\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32_index(dev->of_node, "qcom,perst-regs",
+					 2, &pcie_ep->perst_sep_en);
+	if (ret < 0) {
+		dev_err(dev, "No Perst Separation Enable offset in syscon\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int qcom_pcie_ep_get_resources(struct platform_device *pdev,
+				      struct qcom_pcie_ep *pcie_ep)
+{
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	ret = qcom_pcie_ep_get_io_resources(pdev, pcie_ep);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to get io resources %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_clk_bulk_get(dev, ARRAY_SIZE(qcom_pcie_ep_clks),
+				qcom_pcie_ep_clks);
+	if (ret)
+		return ret;
+
+	pcie_ep->core_reset = devm_reset_control_get_exclusive(dev, "core");
+	if (IS_ERR(pcie_ep->core_reset))
+		return PTR_ERR(pcie_ep->core_reset);
+
+	pcie_ep->reset = devm_gpiod_get(dev, "reset", GPIOD_IN);
+	if (IS_ERR(pcie_ep->reset))
+		return PTR_ERR(pcie_ep->reset);
+
+	pcie_ep->wake = devm_gpiod_get_optional(dev, "wake", GPIOD_OUT_LOW);
+	if (IS_ERR(pcie_ep->wake))
+		return PTR_ERR(pcie_ep->wake);
+
+	pcie_ep->phy = devm_phy_optional_get(&pdev->dev, "pciephy");
+	if (IS_ERR(pcie_ep->phy))
+		ret = PTR_ERR(pcie_ep->phy);
+
+	return ret;
+}
+
+/* TODO: Notify clients about PCIe state change */
+static irqreturn_t qcom_pcie_ep_global_irq_thread(int irq, void *data)
+{
+	struct qcom_pcie_ep *pcie_ep = data;
+	struct dw_pcie *pci = &pcie_ep->pci;
+	struct device *dev = pci->dev;
+	u32 status = readl_relaxed(pcie_ep->parf + PARF_INT_ALL_STATUS);
+	u32 mask = readl_relaxed(pcie_ep->parf + PARF_INT_ALL_MASK);
+	u32 dstate, val;
+
+	writel_relaxed(status, pcie_ep->parf + PARF_INT_ALL_CLEAR);
+	status &= mask;
+
+	if (FIELD_GET(PARF_INT_ALL_LINK_DOWN, status)) {
+		dev_dbg(dev, "Received Linkdown event\n");
+		pcie_ep->link_status = QCOM_PCIE_EP_LINK_DOWN;
+	} else if (FIELD_GET(PARF_INT_ALL_BME, status)) {
+		dev_dbg(dev, "Received BME event. Link is enabled!\n");
+		pcie_ep->link_status = QCOM_PCIE_EP_LINK_ENABLED;
+	} else if (FIELD_GET(PARF_INT_ALL_PM_TURNOFF, status)) {
+		dev_dbg(dev, "Received PM Turn-off event! Entering L23\n");
+		val = readl_relaxed(pcie_ep->parf + PARF_PM_CTRL);
+		val |= PARF_PM_CTRL_READY_ENTR_L23;
+		writel_relaxed(val, pcie_ep->parf + PARF_PM_CTRL);
+	} else if (FIELD_GET(PARF_INT_ALL_DSTATE_CHANGE, status)) {
+		dstate = dw_pcie_readl_dbi(pci, DBI_CON_STATUS) &
+					   DBI_CON_STATUS_POWER_STATE_MASK;
+		dev_dbg(dev, "Received D%d state event\n", dstate);
+		if (dstate == 3) {
+			val = readl_relaxed(pcie_ep->parf + PARF_PM_CTRL);
+			val |= PARF_PM_CTRL_REQ_EXIT_L1;
+			writel_relaxed(val, pcie_ep->parf + PARF_PM_CTRL);
+		}
+	} else if (FIELD_GET(PARF_INT_ALL_LINK_UP, status)) {
+		dev_dbg(dev, "Received Linkup event. Enumeration complete!\n");
+		dw_pcie_ep_linkup(&pci->ep);
+		pcie_ep->link_status = QCOM_PCIE_EP_LINK_UP;
+	} else {
+		dev_dbg(dev, "Received unknown event: %d\n", status);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t qcom_pcie_ep_perst_irq_thread(int irq, void *data)
+{
+	struct qcom_pcie_ep *pcie_ep = data;
+	struct dw_pcie *pci = &pcie_ep->pci;
+	struct device *dev = pci->dev;
+	u32 perst;
+
+	perst = gpiod_get_value(pcie_ep->reset);
+	if (perst) {
+		dev_dbg(dev, "PERST asserted by host. Shutting down the PCIe link!\n");
+		qcom_pcie_perst_assert(pci);
+	} else {
+		dev_dbg(dev, "PERST de-asserted by host. Starting link training!\n");
+		qcom_pcie_perst_deassert(pci);
+	}
+
+	irq_set_irq_type(gpiod_to_irq(pcie_ep->reset),
+			 (perst ? IRQF_TRIGGER_HIGH : IRQF_TRIGGER_LOW));
+
+	return IRQ_HANDLED;
+}
+
+static int qcom_pcie_ep_enable_irq_resources(struct platform_device *pdev,
+					     struct qcom_pcie_ep *pcie_ep)
+{
+	int irq, ret;
+
+	irq = platform_get_irq_byname(pdev, "global");
+	if (irq < 0) {
+		dev_err(&pdev->dev, "Failed to get Global IRQ\n");
+		return irq;
+	}
+
+	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
+					qcom_pcie_ep_global_irq_thread,
+					IRQF_ONESHOT,
+					"global_irq", pcie_ep);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to request Global IRQ\n");
+		return ret;
+	}
+
+	pcie_ep->perst_irq = gpiod_to_irq(pcie_ep->reset);
+	irq_set_status_flags(pcie_ep->perst_irq, IRQ_NOAUTOEN);
+	ret = devm_request_threaded_irq(&pdev->dev, pcie_ep->perst_irq, NULL,
+					qcom_pcie_ep_perst_irq_thread,
+					IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
+					"perst_irq", pcie_ep);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to request PERST IRQ\n");
+		disable_irq(irq);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int qcom_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
+				  enum pci_epc_irq_type type, u16 interrupt_num)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+
+	switch (type) {
+	case PCI_EPC_IRQ_LEGACY:
+		return dw_pcie_ep_raise_legacy_irq(ep, func_no);
+	case PCI_EPC_IRQ_MSI:
+		return dw_pcie_ep_raise_msi_irq(ep, func_no, interrupt_num);
+	default:
+		dev_err(pci->dev, "Unknown IRQ type\n");
+		return -EINVAL;
+	}
+}
+
+static const struct pci_epc_features qcom_pcie_epc_features = {
+	.linkup_notifier = true,
+	.core_init_notifier = true,
+	.msi_capable = true,
+	.msix_capable = false,
+};
+
+static const struct pci_epc_features *
+qcom_pcie_epc_get_features(struct dw_pcie_ep *pci_ep)
+{
+	return &qcom_pcie_epc_features;
+}
+
+static void qcom_pcie_ep_init(struct dw_pcie_ep *ep)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+	enum pci_barno bar;
+
+	for (bar = BAR_0; bar <= BAR_5; bar++)
+		dw_pcie_ep_reset_bar(pci, bar);
+}
+
+static struct dw_pcie_ep_ops pci_ep_ops = {
+	.ep_init = qcom_pcie_ep_init,
+	.raise_irq = qcom_pcie_ep_raise_irq,
+	.get_features = qcom_pcie_epc_get_features,
+};
+
+static int qcom_pcie_ep_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct qcom_pcie_ep *pcie_ep;
+	int ret;
+
+	pcie_ep = devm_kzalloc(dev, sizeof(*pcie_ep), GFP_KERNEL);
+	if (!pcie_ep)
+		return -ENOMEM;
+
+	pcie_ep->pci.dev = dev;
+	pcie_ep->pci.ops = &pci_ops;
+	pcie_ep->pci.ep.ops = &pci_ep_ops;
+	platform_set_drvdata(pdev, pcie_ep);
+
+	ret = qcom_pcie_ep_get_resources(pdev, pcie_ep);
+	if (ret)
+		return ret;
+
+	ret = clk_bulk_prepare_enable(ARRAY_SIZE(qcom_pcie_ep_clks),
+				      qcom_pcie_ep_clks);
+	if (ret)
+		return ret;
+
+	ret = qcom_pcie_ep_core_reset(pcie_ep);
+	if (ret)
+		goto err_disable_clk;
+
+	ret = phy_init(pcie_ep->phy);
+	if (ret)
+		goto err_disable_clk;
+
+	/* PHY needs to be powered on for dw_pcie_ep_init() */
+	ret = phy_power_on(pcie_ep->phy);
+	if (ret)
+		goto err_phy_exit;
+
+	ret = dw_pcie_ep_init(&pcie_ep->pci.ep);
+	if (ret) {
+		dev_err(dev, "Failed to initialize endpoint: %d\n", ret);
+		goto err_phy_power_off;
+	}
+
+	ret = qcom_pcie_ep_enable_irq_resources(pdev, pcie_ep);
+	if (ret)
+		goto err_phy_power_off;
+
+	return 0;
+
+err_phy_power_off:
+	phy_power_off(pcie_ep->phy);
+err_phy_exit:
+	phy_exit(pcie_ep->phy);
+err_disable_clk:
+	clk_bulk_disable_unprepare(ARRAY_SIZE(qcom_pcie_ep_clks),
+				   qcom_pcie_ep_clks);
+
+	return ret;
+}
+
+static int qcom_pcie_ep_remove(struct platform_device *pdev)
+{
+	struct qcom_pcie_ep *pcie_ep = platform_get_drvdata(pdev);
+
+	if (pcie_ep->link_status == QCOM_PCIE_EP_LINK_DISABLED)
+		return 0;
+
+	phy_power_off(pcie_ep->phy);
+	phy_exit(pcie_ep->phy);
+	clk_bulk_disable_unprepare(ARRAY_SIZE(qcom_pcie_ep_clks),
+				   qcom_pcie_ep_clks);
+
+	return 0;
+}
+
+static const struct of_device_id qcom_pcie_ep_match[] = {
+	{ .compatible = "qcom,sdx55-pcie-ep", },
+	{ }
+};
+
+static struct platform_driver qcom_pcie_ep_driver = {
+	.probe	= qcom_pcie_ep_probe,
+	.remove = qcom_pcie_ep_remove,
+	.driver	= {
+		.name = "qcom-pcie-ep",
+		.of_match_table	= qcom_pcie_ep_match,
+	},
+};
+builtin_platform_driver(qcom_pcie_ep_driver);
+
+MODULE_AUTHOR("Siddartha Mohanadoss <[e-mail]>");
+MODULE_AUTHOR("Manivannan Sadhasivam <[e-mail]>");
+MODULE_DESCRIPTION("Qualcomm PCIe Endpoint controller driver");
+MODULE_LICENSE("GPL v2");