[PATCH v3 2/3] PCI: dwc: Add Qualcomm PCIe Endpoint controller driver

[Manivannan Sadhasivam]

Add driver support for Qualcomm PCIe Endpoint controller driver 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.

Co-developed-by: Siddartha Mohanadoss <smohanad@xxxxxxxxxxxxxx>
Signed-off-by: Siddartha Mohanadoss <smohanad@xxxxxxxxxxxxxx>
[mani: restructured the driver and fixed several bugs for upstream]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
 drivers/pci/controller/dwc/Kconfig        |  10 +
 drivers/pci/controller/dwc/Makefile       |   1 +
 drivers/pci/controller/dwc/pcie-qcom-ep.c | 775 ++++++++++++++++++++++
 3 files changed, 786 insertions(+)
 create mode 100644 drivers/pci/controller/dwc/pcie-qcom-ep.c

diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
index 423d35872ce4..eedfe57dadad 100644
--- a/drivers/pci/controller/dwc/Kconfig
+++ b/drivers/pci/controller/dwc/Kconfig
@@ -180,6 +180,16 @@ config PCIE_QCOM
 	  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
diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
index eca805c1a023..abb27642d46b 100644
--- a/drivers/pci/controller/dwc/Makefile
+++ b/drivers/pci/controller/dwc/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_PCI_KEYSTONE) += pci-keystone.o
 obj-$(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_INTEL_GW) += pcie-intel-gw.o
diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
new file mode 100644
index 000000000000..d2cbf5543fbf
--- /dev/null
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -0,0 +1,775 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Qualcomm PCIe Endpoint controller driver
+ *
+ * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ * Author: Siddartha Mohanadoss <smohanad@xxxxxxxxxxxxxx
+ *
+ * Copyright (c) 2021, Linaro Ltd.
+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx
+ */
+
+#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
+
+/* ELBI registers */
+#define ELBI_SYS_STTS				0x08
+
+/* DBI registers */
+#define DBI_CAP_ID_NXT_PTR			0x40
+#define DBI_CON_STATUS				0x44
+#define DBI_DEVICE_CAPABILITIES			0x74
+#define DBI_LINK_CAPABILITIES			0x7c
+#define DBI_LINK_CONTROL2_LINK_STATUS2		0xa0
+#define DBI_L1SUB_CAPABILITY			0x234
+#define DBI_ACK_F_ASPM_CTRL			0x70c
+#define DBI_GEN3_RELATED_OFF			0x890
+#define DBI_AUX_CLK_FREQ			0xb40
+
+#define DBI_L0S_ACCPT_LATENCY_MASK		GENMASK(8, 6)
+#define DBI_L1_ACCPT_LATENCY_MASK		GENMASK(11, 9)
+#define DBI_L0S_EXIT_LATENCY_MASK		GENMASK(14, 12)
+#define DBI_L1_EXIT_LATENCY_MASK		GENMASK(17, 15)
+#define DBI_ACK_N_FTS_MASK			GENMASK(15, 8)
+
+#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,
+};
+
+enum qcom_pcie_ep_irq {
+	QCOM_PCIE_EP_INT_RESERVED,
+	QCOM_PCIE_EP_INT_LINK_DOWN,
+	QCOM_PCIE_EP_INT_BME,
+	QCOM_PCIE_EP_INT_PM_TURNOFF,
+	QCOM_PCIE_EP_INT_DEBUG,
+	QCOM_PCIE_EP_INT_LTR,
+	QCOM_PCIE_EP_INT_MHI_Q6,
+	QCOM_PCIE_EP_INT_MHI_A7,
+	QCOM_PCIE_EP_INT_DSTATE_CHANGE,
+	QCOM_PCIE_EP_INT_L1SUB_TIMEOUT,
+	QCOM_PCIE_EP_INT_MMIO_WRITE,
+	QCOM_PCIE_EP_INT_CFG_WRITE,
+	QCOM_PCIE_EP_INT_BRIDGE_FLUSH_N,
+	QCOM_PCIE_EP_INT_LINK_UP,
+	QCOM_PCIE_EP_INT_AER_LEGACY,
+	QCOM_PCIE_EP_INT_PLS_ERR,
+	QCOM_PCIE_EP_INT_PME_LEGACY,
+	QCOM_PCIE_EP_INT_PLS_PME,
+	QCOM_PCIE_EP_INT_MAX,
+};
+
+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;
+	void __iomem *mmio;
+	struct regmap *perst_map;
+
+	struct reset_control *core_reset;
+	struct gpio_desc *reset;
+	struct gpio_desc *wake;
+	struct phy *phy;
+
+	resource_size_t dbi_phys;
+	resource_size_t atu_phys;
+	resource_size_t mmio_phys;
+	u32 mmio_size;
+	u32 perst_en;
+	u32 perst_sep_en;
+
+	enum qcom_pcie_ep_link_status link_status;
+	int global_irq;
+	int perst_irq;
+};
+
+static void qcom_pcie_ep_enable_ltssm(struct qcom_pcie_ep *pcie_ep)
+{
+	u32 reg;
+
+	reg = readl(pcie_ep->parf + PARF_LTSSM);
+	reg |= BIT(8);
+	writel(reg, pcie_ep->parf + PARF_LTSSM);
+}
+
+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_ep_enable_resources(struct qcom_pcie_ep *pcie_ep)
+{
+	return clk_bulk_prepare_enable(ARRAY_SIZE(qcom_pcie_ep_clks),
+				       qcom_pcie_ep_clks);
+}
+
+static void qcom_pcie_ep_disable_resources(struct qcom_pcie_ep *pcie_ep)
+{
+	clk_bulk_disable_unprepare(ARRAY_SIZE(qcom_pcie_ep_clks),
+				   qcom_pcie_ep_clks);
+}
+
+static int qcom_pcie_ep_core_init(struct qcom_pcie_ep *pcie_ep)
+{
+	struct dw_pcie *pci = &pcie_ep->pci;
+	u32 val;
+
+	/* Disable BDF to SID mapping */
+	val = readl(pcie_ep->parf + PARF_BDF_TO_SID_CFG);
+	val |= BIT(0);
+	writel(val, pcie_ep->parf + PARF_BDF_TO_SID_CFG);
+
+	/* Enable debug IRQ */
+	writel((BIT(3) | BIT(2) | BIT(1)), pcie_ep->parf + PARF_DEBUG_INT_EN);
+
+	/* Configure PCIe to endpoint mode */
+	writel(0x0, pcie_ep->parf + PARF_DEVICE_TYPE);
+
+	/* Configure PCIe core to support 1GB aperture */
+	writel(0x40000000, pcie_ep->parf + PARF_SLV_ADDR_SPACE_SIZE);
+
+	/* Allow entering L1 state */
+	val = readl(pcie_ep->parf + PARF_PM_CTRL);
+	val &= ~BIT(5);
+	writel(val, pcie_ep->parf + PARF_PM_CTRL);
+
+	/* Configure Slave, DBI and iATU base addresses */
+	writel(BIT(0), pcie_ep->parf + PARF_SLV_ADDR_MSB_CTRL);
+	writel(0x200, pcie_ep->parf + PARF_SLV_ADDR_SPACE_SIZE_HI);
+	writel(0x0, pcie_ep->parf + PARF_SLV_ADDR_SPACE_SIZE);
+	writel(0x100, pcie_ep->parf + PARF_DBI_BASE_ADDR_HI);
+	writel(pcie_ep->dbi_phys, pcie_ep->parf + PARF_DBI_BASE_ADDR);
+	writel(0x100, pcie_ep->parf + PARF_ATU_BASE_ADDR_HI);
+	writel(pcie_ep->atu_phys, pcie_ep->parf + PARF_ATU_BASE_ADDR);
+
+	/* Read halts write */
+	writel(0x0, pcie_ep->parf + PARF_AXI_MSTR_RD_HALT_NO_WRITES);
+	/* Write after write halt */
+	writel(BIT(31), pcie_ep->parf + PARF_AXI_MSTR_WR_ADDR_HALT);
+	/* Q2A flush disable */
+	writel(0, pcie_ep->parf + PARF_Q2A_FLUSH);
+
+	/* Disable the DBI Wakeup */
+	writel(BIT(11), pcie_ep->parf + PARF_SYS_CTRL);
+	/* Disable the debouncers */
+	writel(0x73, pcie_ep->parf + PARF_DB_CTRL);
+	/* Disable core clock CGC */
+	writel(BIT(6), pcie_ep->parf + PARF_SYS_CTRL);
+	/* Set AUX power to be on */
+	writel(BIT(4), pcie_ep->parf + PARF_SYS_CTRL);
+	/* Request to exit from L1SS for MSI and LTR MSG */
+	writel(BIT(1), pcie_ep->parf + PARF_CFG_BITS);
+
+	dw_pcie_dbi_ro_wr_en(pci);
+
+	/* Set the PMC Register - to support PME in D0/D3hot/D3cold */
+	val = dw_pcie_readl_dbi(pci, DBI_CAP_ID_NXT_PTR);
+	val |= BIT(31) | BIT(30) | BIT(27);
+	dw_pcie_writel_dbi(pci, DBI_CAP_ID_NXT_PTR, val);
+
+	/* Set the Endpoint L0s Acceptable Latency to 1us (max) */
+	val = dw_pcie_readl_dbi(pci, DBI_DEVICE_CAPABILITIES);
+	val |= FIELD_PREP(DBI_L0S_ACCPT_LATENCY_MASK, 0x7);
+	dw_pcie_writel_dbi(pci, DBI_DEVICE_CAPABILITIES, val);
+
+	/* Set the Endpoint L1 Acceptable Latency to 1us (max) */
+	val = dw_pcie_readl_dbi(pci, DBI_DEVICE_CAPABILITIES);
+	val |= FIELD_PREP(DBI_L1_ACCPT_LATENCY_MASK, 0x7);
+	dw_pcie_writel_dbi(pci, DBI_DEVICE_CAPABILITIES, val);
+
+	/* Set the L0s Exit Latency to 2us-4us = 0x6 */
+	val = dw_pcie_readl_dbi(pci, DBI_LINK_CAPABILITIES);
+	val |= FIELD_PREP(DBI_L0S_EXIT_LATENCY_MASK, 0x6);
+	dw_pcie_writel_dbi(pci, DBI_LINK_CAPABILITIES, val);
+
+	/* Set the L1 Exit Latency to be 32us-64 us = 0x6 */
+	val = dw_pcie_readl_dbi(pci, DBI_LINK_CAPABILITIES);
+	val |= FIELD_PREP(DBI_L1_EXIT_LATENCY_MASK, 0x6);
+	dw_pcie_writel_dbi(pci, DBI_LINK_CAPABILITIES, val);
+
+	/* L1ss is supported */
+	val = dw_pcie_readl_dbi(pci, DBI_L1SUB_CAPABILITY);
+	val |= 0x1f;
+	dw_pcie_writel_dbi(pci, DBI_L1SUB_CAPABILITY, val);
+
+	/* Enable Clock Power Management */
+	val = dw_pcie_readl_dbi(pci, DBI_LINK_CAPABILITIES);
+	val |= BIT(18);
+	dw_pcie_writel_dbi(pci, DBI_LINK_CAPABILITIES, val);
+
+	dw_pcie_dbi_ro_wr_dis(pci);
+
+	/* Set FTS value to match the PHY setting */
+	val = dw_pcie_readl_dbi(pci, DBI_ACK_F_ASPM_CTRL);
+	val |= FIELD_PREP(DBI_ACK_N_FTS_MASK, 0x80);
+	dw_pcie_writel_dbi(pci, DBI_ACK_F_ASPM_CTRL, val);
+
+	dw_pcie_writel_dbi(pci, DBI_AUX_CLK_FREQ, 0x14);
+
+	/* Prevent L1ss wakeup after 100ms */
+	val = dw_pcie_readl_dbi(pci, DBI_GEN3_RELATED_OFF);
+	val &= ~BIT(0);
+	dw_pcie_writel_dbi(pci, DBI_GEN3_RELATED_OFF, val);
+
+	/* Disable SRIS_MODE */
+	val = readl(pcie_ep->parf + PARF_SRIS_MODE);
+	val &= ~BIT(0);
+	writel(val, pcie_ep->parf + PARF_SRIS_MODE);
+
+	writel(0, pcie_ep->parf + PARF_INT_ALL_MASK);
+	val = BIT(QCOM_PCIE_EP_INT_LINK_DOWN) |
+		BIT(QCOM_PCIE_EP_INT_BME) |
+		BIT(QCOM_PCIE_EP_INT_PM_TURNOFF) |
+		BIT(QCOM_PCIE_EP_INT_DSTATE_CHANGE) |
+		BIT(QCOM_PCIE_EP_INT_LINK_UP);
+	writel(val, pcie_ep->parf + PARF_INT_ALL_MASK);
+
+	return 0;
+}
+
+static int qcom_pcie_confirm_linkup(struct dw_pcie *pci)
+{
+	struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
+	u32 reg;
+
+	reg = readl(pcie_ep->elbi + ELBI_SYS_STTS);
+
+	return reg & XMLH_LINK_UP;
+}
+
+static int qcom_pcie_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_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_establish_link(struct dw_pcie *pci)
+{
+	struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
+	struct device *dev = pci->dev;
+	int ret;
+
+	ret = qcom_pcie_ep_enable_resources(pcie_ep);
+	if (ret)
+		return ret;
+
+	ret = qcom_pcie_ep_core_reset(pcie_ep);
+	if (ret)
+		goto err_disable_resources;
+
+	ret = phy_init(pcie_ep->phy);
+	if (ret)
+		goto err_disable_resources;
+
+	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);
+
+	ret = qcom_pcie_ep_core_init(pcie_ep);
+	if (ret) {
+		dev_err(dev, "Failed to init controller: %d\n", ret);
+		goto err_phy_power_off;
+	}
+
+	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_phys, 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);
+
+	qcom_pcie_ep_enable_ltssm(pcie_ep);
+
+	return 0;
+
+err_phy_power_off:
+	phy_power_off(pcie_ep->phy);
+err_phy_exit:
+	phy_exit(pcie_ep->phy);
+err_disable_resources:
+	qcom_pcie_ep_disable_resources(pcie_ep);
+
+	return ret;
+}
+
+static void qcom_pcie_disable_link(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);
+	qcom_pcie_ep_disable_resources(pcie_ep);
+	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_confirm_linkup,
+	.start_link = qcom_pcie_start_link,
+	.stop_link = qcom_pcie_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;
+	pcie_ep->dbi_phys = res->start;
+
+	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);
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "atu");
+	pci->atu_base = devm_pci_remap_cfg_resource(dev, res);
+	if (IS_ERR(pci->atu_base))
+		return PTR_ERR(pci->atu_base);
+	pcie_ep->atu_phys = res->start;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mmio");
+	pcie_ep->mmio = devm_ioremap_resource(dev, res);
+	if (IS_ERR(pcie_ep->mmio))
+		return PTR_ERR(pcie_ep->mmio);
+	pcie_ep->mmio_phys = res->start;
+	pcie_ep->mmio_size = resource_size(res);
+
+	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_threaded_irq(int irq, void *data)
+{
+	struct qcom_pcie_ep *pcie_ep = data;
+	struct dw_pcie *pci = &pcie_ep->pci;
+	struct device *dev = pci->dev;
+	unsigned long status = readl(pcie_ep->parf + PARF_INT_ALL_STATUS);
+	u32 mask = readl(pcie_ep->parf + PARF_INT_ALL_MASK);
+	u32 dstate, event, val;
+
+	writel(status, pcie_ep->parf + PARF_INT_ALL_CLEAR);
+	status &= mask;
+
+	for_each_set_bit(event, &status, QCOM_PCIE_EP_INT_MAX) {
+		switch (event) {
+		case QCOM_PCIE_EP_INT_LINK_DOWN:
+			dev_dbg(dev, "Received Linkdown event\n");
+			pcie_ep->link_status = QCOM_PCIE_EP_LINK_DOWN;
+			break;
+		case QCOM_PCIE_EP_INT_BME:
+			dev_dbg(dev, "Received BME event. Link is enabled!\n");
+			pcie_ep->link_status = QCOM_PCIE_EP_LINK_ENABLED;
+			break;
+		case QCOM_PCIE_EP_INT_PM_TURNOFF:
+			dev_dbg(dev, "Received PM Turn-off event! Entering L23\n");
+			val = readl(pcie_ep->parf + PARF_PM_CTRL);
+			val |= BIT(2);
+			writel(val, pcie_ep->parf + PARF_PM_CTRL);
+			break;
+		case QCOM_PCIE_EP_INT_DSTATE_CHANGE:
+			dstate = dw_pcie_readl_dbi(pci, DBI_CON_STATUS) & 0x3;
+			dev_dbg(dev, "Received D%d state event\n", dstate);
+			if (dstate == 3) {
+				val = readl(pcie_ep->parf + PARF_PM_CTRL);
+				val |= BIT(1);
+				writel(val, pcie_ep->parf + PARF_PM_CTRL);
+			}
+			break;
+		case QCOM_PCIE_EP_INT_LINK_UP:
+			dev_dbg(dev, "Received Linkup event. Enumeration complete!\n");
+			dw_pcie_ep_linkup(&pci->ep);
+			pcie_ep->link_status = QCOM_PCIE_EP_LINK_UP;
+			break;
+		default:
+			dev_dbg(dev, "Received unknown event: %d\n", event);
+			break;
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t qcom_pcie_ep_perst_threaded_irq(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 de-asserted by host. Starting link training!\n");
+		qcom_pcie_establish_link(pci);
+	} else {
+		dev_dbg(dev, "PERST asserted by host. Shutting down the PCIe link!\n");
+		qcom_pcie_disable_link(pci);
+	}
+
+	irq_set_irq_type(gpiod_to_irq(pcie_ep->reset),
+			 (perst ? IRQF_TRIGGER_LOW : IRQF_TRIGGER_HIGH));
+
+	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_threaded_irq,
+					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_threaded_irq,
+					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 = qcom_pcie_ep_enable_resources(pcie_ep);
+	if (ret)
+		return ret;
+
+	ret = qcom_pcie_ep_core_reset(pcie_ep);
+	if (ret)
+		goto err_disable_resources;
+
+	ret = phy_init(pcie_ep->phy);
+	if (ret)
+		goto err_disable_resources;
+
+	/* 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_resources:
+	qcom_pcie_ep_disable_resources(pcie_ep);
+
+	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);
+	qcom_pcie_ep_disable_resources(pcie_ep);
+
+	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 <smohanad@xxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Qualcomm PCIe Endpoint controller driver");
+MODULE_LICENSE("GPL v2");
-- 
2.25.1