drivers/pci/host/pci-imx6.c - kernel/msm-4.9 - Gitiles

 /*
  * PCIe host controller driver for Freescale i.MX6 SoCs
  *
  * Copyright (C) 2013 Kosagi
  *		http://www.kosagi.com
  *
  * Author: Sean Cross <xobs@kosagi.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/gpio.h>
 #include <linux/kernel.h>
 #include <linux/mfd/syscon.h>
 #include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
 #include <linux/module.h>
 #include <linux/of_gpio.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/resource.h>
 #include <linux/signal.h>
 #include <linux/types.h>
 #include <linux/interrupt.h>

 #include "pcie-designware.h"

 #define to_imx6_pcie(x)	container_of(x, struct imx6_pcie, pp)

 struct imx6_pcie {
 	int			reset_gpio;
 	struct clk		*pcie_bus;
 	struct clk		*pcie_phy;
 	struct clk		*pcie;
 	struct pcie_port	pp;
 	struct regmap		*iomuxc_gpr;
 	void __iomem		*mem_base;
 };

 /* PCIe Root Complex registers (memory-mapped) */
 #define PCIE_RC_LCR				0x7c
 #define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1	0x1
 #define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN2	0x2
 #define PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK	0xf

 #define PCIE_RC_LCSR				0x80

 /* PCIe Port Logic registers (memory-mapped) */
 #define PL_OFFSET 0x700
 #define PCIE_PL_PFLR (PL_OFFSET + 0x08)
 #define PCIE_PL_PFLR_LINK_STATE_MASK		(0x3f << 16)
 #define PCIE_PL_PFLR_FORCE_LINK			(1 << 15)
 #define PCIE_PHY_DEBUG_R0 (PL_OFFSET + 0x28)
 #define PCIE_PHY_DEBUG_R1 (PL_OFFSET + 0x2c)
 #define PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING	(1 << 29)
 #define PCIE_PHY_DEBUG_R1_XMLH_LINK_UP		(1 << 4)

 #define PCIE_PHY_CTRL (PL_OFFSET + 0x114)
 #define PCIE_PHY_CTRL_DATA_LOC 0
 #define PCIE_PHY_CTRL_CAP_ADR_LOC 16
 #define PCIE_PHY_CTRL_CAP_DAT_LOC 17
 #define PCIE_PHY_CTRL_WR_LOC 18
 #define PCIE_PHY_CTRL_RD_LOC 19

 #define PCIE_PHY_STAT (PL_OFFSET + 0x110)
 #define PCIE_PHY_STAT_ACK_LOC 16

 #define PCIE_LINK_WIDTH_SPEED_CONTROL	0x80C
 #define PORT_LOGIC_SPEED_CHANGE		(0x1 << 17)

 /* PHY registers (not memory-mapped) */
 #define PCIE_PHY_RX_ASIC_OUT 0x100D

 #define PHY_RX_OVRD_IN_LO 0x1005
 #define PHY_RX_OVRD_IN_LO_RX_DATA_EN (1 << 5)
 #define PHY_RX_OVRD_IN_LO_RX_PLL_EN (1 << 3)

 static int pcie_phy_poll_ack(void __iomem *dbi_base, int exp_val)
 {
 	u32 val;
 	u32 max_iterations = 10;
 	u32 wait_counter = 0;

 	do {
 		val = readl(dbi_base + PCIE_PHY_STAT);
 		val = (val >> PCIE_PHY_STAT_ACK_LOC) & 0x1;
 		wait_counter++;

 		if (val == exp_val)
 			return 0;

 		udelay(1);
 	} while (wait_counter < max_iterations);

 	return -ETIMEDOUT;
 }

 static int pcie_phy_wait_ack(void __iomem *dbi_base, int addr)
 {
 	u32 val;
 	int ret;

 	val = addr << PCIE_PHY_CTRL_DATA_LOC;
 	writel(val, dbi_base + PCIE_PHY_CTRL);

 	val |= (0x1 << PCIE_PHY_CTRL_CAP_ADR_LOC);
 	writel(val, dbi_base + PCIE_PHY_CTRL);

 	ret = pcie_phy_poll_ack(dbi_base, 1);
 	if (ret)
 		return ret;

 	val = addr << PCIE_PHY_CTRL_DATA_LOC;
 	writel(val, dbi_base + PCIE_PHY_CTRL);

 	return pcie_phy_poll_ack(dbi_base, 0);
 }

 /* Read from the 16-bit PCIe PHY control registers (not memory-mapped) */
 static int pcie_phy_read(void __iomem *dbi_base, int addr , int *data)
 {
 	u32 val, phy_ctl;
 	int ret;

 	ret = pcie_phy_wait_ack(dbi_base, addr);
 	if (ret)
 		return ret;

 	/* assert Read signal */
 	phy_ctl = 0x1 << PCIE_PHY_CTRL_RD_LOC;
 	writel(phy_ctl, dbi_base + PCIE_PHY_CTRL);

 	ret = pcie_phy_poll_ack(dbi_base, 1);
 	if (ret)
 		return ret;

 	val = readl(dbi_base + PCIE_PHY_STAT);
 	*data = val & 0xffff;

 	/* deassert Read signal */
 	writel(0x00, dbi_base + PCIE_PHY_CTRL);

 	return pcie_phy_poll_ack(dbi_base, 0);
 }

 static int pcie_phy_write(void __iomem *dbi_base, int addr, int data)
 {
 	u32 var;
 	int ret;

 	/* write addr */
 	/* cap addr */
 	ret = pcie_phy_wait_ack(dbi_base, addr);
 	if (ret)
 		return ret;

 	var = data << PCIE_PHY_CTRL_DATA_LOC;
 	writel(var, dbi_base + PCIE_PHY_CTRL);

 	/* capture data */
 	var |= (0x1 << PCIE_PHY_CTRL_CAP_DAT_LOC);
 	writel(var, dbi_base + PCIE_PHY_CTRL);

 	ret = pcie_phy_poll_ack(dbi_base, 1);
 	if (ret)
 		return ret;

 	/* deassert cap data */
 	var = data << PCIE_PHY_CTRL_DATA_LOC;
 	writel(var, dbi_base + PCIE_PHY_CTRL);

 	/* wait for ack de-assertion */
 	ret = pcie_phy_poll_ack(dbi_base, 0);
 	if (ret)
 		return ret;

 	/* assert wr signal */
 	var = 0x1 << PCIE_PHY_CTRL_WR_LOC;
 	writel(var, dbi_base + PCIE_PHY_CTRL);

 	/* wait for ack */
 	ret = pcie_phy_poll_ack(dbi_base, 1);
 	if (ret)
 		return ret;

 	/* deassert wr signal */
 	var = data << PCIE_PHY_CTRL_DATA_LOC;
 	writel(var, dbi_base + PCIE_PHY_CTRL);

 	/* wait for ack de-assertion */
 	ret = pcie_phy_poll_ack(dbi_base, 0);
 	if (ret)
 		return ret;

 	writel(0x0, dbi_base + PCIE_PHY_CTRL);

 	return 0;
 }

 /*  Added for PCI abort handling */
 static int imx6q_pcie_abort_handler(unsigned long addr,
 		unsigned int fsr, struct pt_regs *regs)
 {
 	return 0;
 }

 static int imx6_pcie_assert_core_reset(struct pcie_port *pp)
 {
 	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
 	u32 val, gpr1, gpr12;

 	/*
 	 * If the bootloader already enabled the link we need some special
 	 * handling to get the core back into a state where it is safe to
 	 * touch it for configuration.  As there is no dedicated reset signal
 	 * wired up for MX6QDL, we need to manually force LTSSM into "detect"
 	 * state before completely disabling LTSSM, which is a prerequisite
 	 * for core configuration.
 	 *
 	 * If both LTSSM_ENABLE and REF_SSP_ENABLE are active we have a strong
 	 * indication that the bootloader activated the link.
 	 */
 	regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1, &gpr1);
 	regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12, &gpr12);

 	if ((gpr1 & IMX6Q_GPR1_PCIE_REF_CLK_EN) &&
 	    (gpr12 & IMX6Q_GPR12_PCIE_CTL_2)) {
 		val = readl(pp->dbi_base + PCIE_PL_PFLR);
 		val &= ~PCIE_PL_PFLR_LINK_STATE_MASK;
 		val |= PCIE_PL_PFLR_FORCE_LINK;
 		writel(val, pp->dbi_base + PCIE_PL_PFLR);

 		regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
 				IMX6Q_GPR12_PCIE_CTL_2, 0 << 10);
 	}

 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
 			IMX6Q_GPR1_PCIE_TEST_PD, 1 << 18);
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
 			IMX6Q_GPR1_PCIE_REF_CLK_EN, 0 << 16);

 	return 0;
 }

 static int imx6_pcie_deassert_core_reset(struct pcie_port *pp)
 {
 	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
 	int ret;

 	ret = clk_prepare_enable(imx6_pcie->pcie_phy);
 	if (ret) {
 		dev_err(pp->dev, "unable to enable pcie_phy clock\n");
 		goto err_pcie_phy;
 	}

 	ret = clk_prepare_enable(imx6_pcie->pcie_bus);
 	if (ret) {
 		dev_err(pp->dev, "unable to enable pcie_bus clock\n");
 		goto err_pcie_bus;
 	}

 	ret = clk_prepare_enable(imx6_pcie->pcie);
 	if (ret) {
 		dev_err(pp->dev, "unable to enable pcie clock\n");
 		goto err_pcie;
 	}

 	/* power up core phy and enable ref clock */
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
 			IMX6Q_GPR1_PCIE_TEST_PD, 0 << 18);
 	/*
 	 * the async reset input need ref clock to sync internally,
 	 * when the ref clock comes after reset, internal synced
 	 * reset time is too short, cannot meet the requirement.
 	 * add one ~10us delay here.
 	 */
 	udelay(10);
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
 			IMX6Q_GPR1_PCIE_REF_CLK_EN, 1 << 16);

 	/* allow the clocks to stabilize */
 	usleep_range(200, 500);

 	/* Some boards don't have PCIe reset GPIO. */
 	if (gpio_is_valid(imx6_pcie->reset_gpio)) {
 		gpio_set_value(imx6_pcie->reset_gpio, 0);
 		msleep(100);
 		gpio_set_value(imx6_pcie->reset_gpio, 1);
 	}
 	return 0;

 err_pcie:
 	clk_disable_unprepare(imx6_pcie->pcie_bus);
 err_pcie_bus:
 	clk_disable_unprepare(imx6_pcie->pcie_phy);
 err_pcie_phy:
 	return ret;

 }

 static void imx6_pcie_init_phy(struct pcie_port *pp)
 {
 	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);

 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
 			IMX6Q_GPR12_PCIE_CTL_2, 0 << 10);

 	/* configure constant input signal to the pcie ctrl and phy */
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
 			IMX6Q_GPR12_DEVICE_TYPE, PCI_EXP_TYPE_ROOT_PORT << 12);
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
 			IMX6Q_GPR12_LOS_LEVEL, 9 << 4);

 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
 			IMX6Q_GPR8_TX_DEEMPH_GEN1, 0 << 0);
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
 			IMX6Q_GPR8_TX_DEEMPH_GEN2_3P5DB, 0 << 6);
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
 			IMX6Q_GPR8_TX_DEEMPH_GEN2_6DB, 20 << 12);
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
 			IMX6Q_GPR8_TX_SWING_FULL, 127 << 18);
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
 			IMX6Q_GPR8_TX_SWING_LOW, 127 << 25);
 }

 static int imx6_pcie_wait_for_link(struct pcie_port *pp)
 {
 	unsigned int retries;

 	for (retries = 0; retries < 200; retries++) {
 		if (dw_pcie_link_up(pp))
 			return 0;
 		usleep_range(100, 1000);
 	}

 	dev_err(pp->dev, "phy link never came up\n");
 	dev_dbg(pp->dev, "DEBUG_R0: 0x%08x, DEBUG_R1: 0x%08x\n",
 		readl(pp->dbi_base + PCIE_PHY_DEBUG_R0),
 		readl(pp->dbi_base + PCIE_PHY_DEBUG_R1));
 	return -EINVAL;
 }

 static int imx6_pcie_wait_for_speed_change(struct pcie_port *pp)
 {
 	u32 tmp;
 	unsigned int retries;

 	for (retries = 0; retries < 200; retries++) {
 		tmp = readl(pp->dbi_base + PCIE_LINK_WIDTH_SPEED_CONTROL);
 		/* Test if the speed change finished. */
 		if (!(tmp & PORT_LOGIC_SPEED_CHANGE))
 			return 0;
 		usleep_range(100, 1000);
 	}

 	dev_err(pp->dev, "Speed change timeout\n");
 	return -EINVAL;
 }

 static irqreturn_t imx6_pcie_msi_handler(int irq, void *arg)
 {
 	struct pcie_port *pp = arg;

 	return dw_handle_msi_irq(pp);
 }

 static int imx6_pcie_establish_link(struct pcie_port *pp)
 {
 	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
 	u32 tmp;
 	int ret;

 	/*
 	 * Force Gen1 operation when starting the link.  In case the link is
 	 * started in Gen2 mode, there is a possibility the devices on the
 	 * bus will not be detected at all.  This happens with PCIe switches.
 	 */
 	tmp = readl(pp->dbi_base + PCIE_RC_LCR);
 	tmp &= ~PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK;
 	tmp |= PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1;
 	writel(tmp, pp->dbi_base + PCIE_RC_LCR);

 	/* Start LTSSM. */
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
 			IMX6Q_GPR12_PCIE_CTL_2, 1 << 10);

 	ret = imx6_pcie_wait_for_link(pp);
 	if (ret)
 		return ret;

 	/* Allow Gen2 mode after the link is up. */
 	tmp = readl(pp->dbi_base + PCIE_RC_LCR);
 	tmp &= ~PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK;
 	tmp |= PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN2;
 	writel(tmp, pp->dbi_base + PCIE_RC_LCR);

 	/*
 	 * Start Directed Speed Change so the best possible speed both link
 	 * partners support can be negotiated.
 	 */
 	tmp = readl(pp->dbi_base + PCIE_LINK_WIDTH_SPEED_CONTROL);
 	tmp |= PORT_LOGIC_SPEED_CHANGE;
 	writel(tmp, pp->dbi_base + PCIE_LINK_WIDTH_SPEED_CONTROL);

 	ret = imx6_pcie_wait_for_speed_change(pp);
 	if (ret) {
 		dev_err(pp->dev, "Failed to bring link up!\n");
 		return ret;
 	}

 	/* Make sure link training is finished as well! */
 	ret = imx6_pcie_wait_for_link(pp);
 	if (ret) {
 		dev_err(pp->dev, "Failed to bring link up!\n");
 		return ret;
 	}

 	tmp = readl(pp->dbi_base + PCIE_RC_LCSR);
 	dev_dbg(pp->dev, "Link up, Gen=%i\n", (tmp >> 16) & 0xf);
 	return 0;
 }

 static void imx6_pcie_host_init(struct pcie_port *pp)
 {
 	imx6_pcie_assert_core_reset(pp);

 	imx6_pcie_init_phy(pp);

 	imx6_pcie_deassert_core_reset(pp);

 	dw_pcie_setup_rc(pp);

 	imx6_pcie_establish_link(pp);

 	if (IS_ENABLED(CONFIG_PCI_MSI))
 		dw_pcie_msi_init(pp);
 }

 static void imx6_pcie_reset_phy(struct pcie_port *pp)
 {
 	u32 tmp;

 	pcie_phy_read(pp->dbi_base, PHY_RX_OVRD_IN_LO, &tmp);
 	tmp |= (PHY_RX_OVRD_IN_LO_RX_DATA_EN |
 		PHY_RX_OVRD_IN_LO_RX_PLL_EN);
 	pcie_phy_write(pp->dbi_base, PHY_RX_OVRD_IN_LO, tmp);

 	usleep_range(2000, 3000);

 	pcie_phy_read(pp->dbi_base, PHY_RX_OVRD_IN_LO, &tmp);
 	tmp &= ~(PHY_RX_OVRD_IN_LO_RX_DATA_EN |
 		  PHY_RX_OVRD_IN_LO_RX_PLL_EN);
 	pcie_phy_write(pp->dbi_base, PHY_RX_OVRD_IN_LO, tmp);
 }

 static int imx6_pcie_link_up(struct pcie_port *pp)
 {
 	u32 rc, debug_r0, rx_valid;
 	int count = 5;

 	/*
 	 * Test if the PHY reports that the link is up and also that the LTSSM
 	 * training finished. There are three possible states of the link when
 	 * this code is called:
 	 * 1) The link is DOWN (unlikely)
 	 *     The link didn't come up yet for some reason. This usually means
 	 *     we have a real problem somewhere. Reset the PHY and exit. This
 	 *     state calls for inspection of the DEBUG registers.
 	 * 2) The link is UP, but still in LTSSM training
 	 *     Wait for the training to finish, which should take a very short
 	 *     time. If the training does not finish, we have a problem and we
 	 *     need to inspect the DEBUG registers. If the training does finish,
 	 *     the link is up and operating correctly.
 	 * 3) The link is UP and no longer in LTSSM training
 	 *     The link is up and operating correctly.
 	 */
 	while (1) {
 		rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
 		if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP))
 			break;
 		if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
 			return 1;
 		if (!count--)
 			break;
 		dev_dbg(pp->dev, "Link is up, but still in training\n");
 		/*
 		 * Wait a little bit, then re-check if the link finished
 		 * the training.
 		 */
 		usleep_range(1000, 2000);
 	}
 	/*
 	 * From L0, initiate MAC entry to gen2 if EP/RC supports gen2.
 	 * Wait 2ms (LTSSM timeout is 24ms, PHY lock is ~5us in gen2).
 	 * If (MAC/LTSSM.state == Recovery.RcvrLock)
 	 * && (PHY/rx_valid==0) then pulse PHY/rx_reset. Transition
 	 * to gen2 is stuck
 	 */
 	pcie_phy_read(pp->dbi_base, PCIE_PHY_RX_ASIC_OUT, &rx_valid);
 	debug_r0 = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0);

 	if (rx_valid & 0x01)
 		return 0;

 	if ((debug_r0 & 0x3f) != 0x0d)
 		return 0;

 	dev_err(pp->dev, "transition to gen2 is stuck, reset PHY!\n");
 	dev_dbg(pp->dev, "debug_r0=%08x debug_r1=%08x\n", debug_r0, rc);

 	imx6_pcie_reset_phy(pp);

 	return 0;
 }

 static struct pcie_host_ops imx6_pcie_host_ops = {
 	.link_up = imx6_pcie_link_up,
 	.host_init = imx6_pcie_host_init,
 };

 static int __init imx6_add_pcie_port(struct pcie_port *pp,
 			struct platform_device *pdev)
 {
 	int ret;

 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
 		pp->msi_irq = platform_get_irq_byname(pdev, "msi");
 		if (pp->msi_irq <= 0) {
 			dev_err(&pdev->dev, "failed to get MSI irq\n");
 			return -ENODEV;
 		}

 		ret = devm_request_irq(&pdev->dev, pp->msi_irq,
 				       imx6_pcie_msi_handler,
 				       IRQF_SHARED, "mx6-pcie-msi", pp);
 		if (ret) {
 			dev_err(&pdev->dev, "failed to request MSI irq\n");
 			return -ENODEV;
 		}
 	}

 	pp->root_bus_nr = -1;
 	pp->ops = &imx6_pcie_host_ops;

 	ret = dw_pcie_host_init(pp);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to initialize host\n");
 		return ret;
 	}

 	return 0;
 }

 static int __init imx6_pcie_probe(struct platform_device *pdev)
 {
 	struct imx6_pcie *imx6_pcie;
 	struct pcie_port *pp;
 	struct device_node *np = pdev->dev.of_node;
 	struct resource *dbi_base;
 	int ret;

 	imx6_pcie = devm_kzalloc(&pdev->dev, sizeof(*imx6_pcie), GFP_KERNEL);
 	if (!imx6_pcie)
 		return -ENOMEM;

 	pp = &imx6_pcie->pp;
 	pp->dev = &pdev->dev;

 	/* Added for PCI abort handling */
 	hook_fault_code(16 + 6, imx6q_pcie_abort_handler, SIGBUS, 0,
 		"imprecise external abort");

 	dbi_base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	pp->dbi_base = devm_ioremap_resource(&pdev->dev, dbi_base);
 	if (IS_ERR(pp->dbi_base))
 		return PTR_ERR(pp->dbi_base);

 	/* Fetch GPIOs */
 	imx6_pcie->reset_gpio = of_get_named_gpio(np, "reset-gpio", 0);
 	if (gpio_is_valid(imx6_pcie->reset_gpio)) {
 		ret = devm_gpio_request_one(&pdev->dev, imx6_pcie->reset_gpio,
 					    GPIOF_OUT_INIT_LOW, "PCIe reset");
 		if (ret) {
 			dev_err(&pdev->dev, "unable to get reset gpio\n");
 			return ret;
 		}
 	}

 	/* Fetch clocks */
 	imx6_pcie->pcie_phy = devm_clk_get(&pdev->dev, "pcie_phy");
 	if (IS_ERR(imx6_pcie->pcie_phy)) {
 		dev_err(&pdev->dev,
 			"pcie_phy clock source missing or invalid\n");
 		return PTR_ERR(imx6_pcie->pcie_phy);
 	}

 	imx6_pcie->pcie_bus = devm_clk_get(&pdev->dev, "pcie_bus");
 	if (IS_ERR(imx6_pcie->pcie_bus)) {
 		dev_err(&pdev->dev,
 			"pcie_bus clock source missing or invalid\n");
 		return PTR_ERR(imx6_pcie->pcie_bus);
 	}

 	imx6_pcie->pcie = devm_clk_get(&pdev->dev, "pcie");
 	if (IS_ERR(imx6_pcie->pcie)) {
 		dev_err(&pdev->dev,
 			"pcie clock source missing or invalid\n");
 		return PTR_ERR(imx6_pcie->pcie);
 	}

 	/* Grab GPR config register range */
 	imx6_pcie->iomuxc_gpr =
 		 syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr");
 	if (IS_ERR(imx6_pcie->iomuxc_gpr)) {
 		dev_err(&pdev->dev, "unable to find iomuxc registers\n");
 		return PTR_ERR(imx6_pcie->iomuxc_gpr);
 	}

 	ret = imx6_add_pcie_port(pp, pdev);
 	if (ret < 0)
 		return ret;

 	platform_set_drvdata(pdev, imx6_pcie);
 	return 0;
 }

 static void imx6_pcie_shutdown(struct platform_device *pdev)
 {
 	struct imx6_pcie *imx6_pcie = platform_get_drvdata(pdev);

 	/* bring down link, so bootloader gets clean state in case of reboot */
 	imx6_pcie_assert_core_reset(&imx6_pcie->pp);
 }

 static const struct of_device_id imx6_pcie_of_match[] = {
 	{ .compatible = "fsl,imx6q-pcie", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, imx6_pcie_of_match);

 static struct platform_driver imx6_pcie_driver = {
 	.driver = {
 		.name	= "imx6q-pcie",
 		.of_match_table = imx6_pcie_of_match,
 	},
 	.shutdown = imx6_pcie_shutdown,
 };

 /* Freescale PCIe driver does not allow module unload */

 static int __init imx6_pcie_init(void)
 {
 	return platform_driver_probe(&imx6_pcie_driver, imx6_pcie_probe);
 }
 module_init(imx6_pcie_init);

 MODULE_AUTHOR("Sean Cross <xobs@kosagi.com>");
 MODULE_DESCRIPTION("Freescale i.MX6 PCIe host controller driver");
 MODULE_LICENSE("GPL v2");
	/*
	* PCIe host controller driver for Freescale i.MX6 SoCs
	*
	* Copyright (C) 2013 Kosagi
	* http://www.kosagi.com
	*
	* Author: Sean Cross <xobs@kosagi.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/gpio.h>
	#include <linux/kernel.h>
	#include <linux/mfd/syscon.h>
	#include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
	#include <linux/module.h>
	#include <linux/of_gpio.h>
	#include <linux/pci.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>
	#include <linux/resource.h>
	#include <linux/signal.h>
	#include <linux/types.h>
	#include <linux/interrupt.h>

	#include "pcie-designware.h"

	#define to_imx6_pcie(x) container_of(x, struct imx6_pcie, pp)

	struct imx6_pcie {
	int reset_gpio;
	struct clk *pcie_bus;
	struct clk *pcie_phy;
	struct clk *pcie;
	struct pcie_port pp;
	struct regmap *iomuxc_gpr;
	void __iomem *mem_base;
	};

	/* PCIe Root Complex registers (memory-mapped) */
	#define PCIE_RC_LCR 0x7c
	#define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1 0x1
	#define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN2 0x2
	#define PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK 0xf

	#define PCIE_RC_LCSR 0x80

	/* PCIe Port Logic registers (memory-mapped) */
	#define PL_OFFSET 0x700
	#define PCIE_PL_PFLR (PL_OFFSET + 0x08)
	#define PCIE_PL_PFLR_LINK_STATE_MASK (0x3f << 16)
	#define PCIE_PL_PFLR_FORCE_LINK (1 << 15)
	#define PCIE_PHY_DEBUG_R0 (PL_OFFSET + 0x28)
	#define PCIE_PHY_DEBUG_R1 (PL_OFFSET + 0x2c)
	#define PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING (1 << 29)
	#define PCIE_PHY_DEBUG_R1_XMLH_LINK_UP (1 << 4)

	#define PCIE_PHY_CTRL (PL_OFFSET + 0x114)
	#define PCIE_PHY_CTRL_DATA_LOC 0
	#define PCIE_PHY_CTRL_CAP_ADR_LOC 16
	#define PCIE_PHY_CTRL_CAP_DAT_LOC 17
	#define PCIE_PHY_CTRL_WR_LOC 18
	#define PCIE_PHY_CTRL_RD_LOC 19

	#define PCIE_PHY_STAT (PL_OFFSET + 0x110)
	#define PCIE_PHY_STAT_ACK_LOC 16

	#define PCIE_LINK_WIDTH_SPEED_CONTROL 0x80C
	#define PORT_LOGIC_SPEED_CHANGE (0x1 << 17)

	/* PHY registers (not memory-mapped) */
	#define PCIE_PHY_RX_ASIC_OUT 0x100D

	#define PHY_RX_OVRD_IN_LO 0x1005
	#define PHY_RX_OVRD_IN_LO_RX_DATA_EN (1 << 5)
	#define PHY_RX_OVRD_IN_LO_RX_PLL_EN (1 << 3)

	static int pcie_phy_poll_ack(void __iomem *dbi_base, int exp_val)
	{
	u32 val;
	u32 max_iterations = 10;
	u32 wait_counter = 0;

	do {
	val = readl(dbi_base + PCIE_PHY_STAT);
	val = (val >> PCIE_PHY_STAT_ACK_LOC) & 0x1;
	wait_counter++;

	if (val == exp_val)
	return 0;

	udelay(1);
	} while (wait_counter < max_iterations);

	return -ETIMEDOUT;
	}

	static int pcie_phy_wait_ack(void __iomem *dbi_base, int addr)
	{
	u32 val;
	int ret;

	val = addr << PCIE_PHY_CTRL_DATA_LOC;
	writel(val, dbi_base + PCIE_PHY_CTRL);

	val \|= (0x1 << PCIE_PHY_CTRL_CAP_ADR_LOC);
	writel(val, dbi_base + PCIE_PHY_CTRL);

	ret = pcie_phy_poll_ack(dbi_base, 1);
	if (ret)
	return ret;

	val = addr << PCIE_PHY_CTRL_DATA_LOC;
	writel(val, dbi_base + PCIE_PHY_CTRL);

	return pcie_phy_poll_ack(dbi_base, 0);
	}

	/* Read from the 16-bit PCIe PHY control registers (not memory-mapped) */
	static int pcie_phy_read(void __iomem dbi_base, int addr , int data)
	{
	u32 val, phy_ctl;
	int ret;

	ret = pcie_phy_wait_ack(dbi_base, addr);
	if (ret)
	return ret;

	/* assert Read signal */
	phy_ctl = 0x1 << PCIE_PHY_CTRL_RD_LOC;
	writel(phy_ctl, dbi_base + PCIE_PHY_CTRL);

	ret = pcie_phy_poll_ack(dbi_base, 1);
	if (ret)
	return ret;

	val = readl(dbi_base + PCIE_PHY_STAT);
	*data = val & 0xffff;

	/* deassert Read signal */
	writel(0x00, dbi_base + PCIE_PHY_CTRL);

	return pcie_phy_poll_ack(dbi_base, 0);
	}

	static int pcie_phy_write(void __iomem *dbi_base, int addr, int data)
	{
	u32 var;
	int ret;

	/* write addr */
	/* cap addr */
	ret = pcie_phy_wait_ack(dbi_base, addr);
	if (ret)
	return ret;

	var = data << PCIE_PHY_CTRL_DATA_LOC;
	writel(var, dbi_base + PCIE_PHY_CTRL);

	/* capture data */
	var \|= (0x1 << PCIE_PHY_CTRL_CAP_DAT_LOC);
	writel(var, dbi_base + PCIE_PHY_CTRL);

	ret = pcie_phy_poll_ack(dbi_base, 1);
	if (ret)
	return ret;

	/* deassert cap data */
	var = data << PCIE_PHY_CTRL_DATA_LOC;
	writel(var, dbi_base + PCIE_PHY_CTRL);

	/* wait for ack de-assertion */
	ret = pcie_phy_poll_ack(dbi_base, 0);
	if (ret)
	return ret;

	/* assert wr signal */
	var = 0x1 << PCIE_PHY_CTRL_WR_LOC;
	writel(var, dbi_base + PCIE_PHY_CTRL);

	/* wait for ack */
	ret = pcie_phy_poll_ack(dbi_base, 1);
	if (ret)
	return ret;

	/* deassert wr signal */
	var = data << PCIE_PHY_CTRL_DATA_LOC;
	writel(var, dbi_base + PCIE_PHY_CTRL);

	/* wait for ack de-assertion */
	ret = pcie_phy_poll_ack(dbi_base, 0);
	if (ret)
	return ret;

	writel(0x0, dbi_base + PCIE_PHY_CTRL);

	return 0;
	}

	/* Added for PCI abort handling */
	static int imx6q_pcie_abort_handler(unsigned long addr,
	unsigned int fsr, struct pt_regs *regs)
	{
	return 0;
	}

	static int imx6_pcie_assert_core_reset(struct pcie_port *pp)
	{
	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
	u32 val, gpr1, gpr12;

	/*
	* If the bootloader already enabled the link we need some special
	* handling to get the core back into a state where it is safe to
	* touch it for configuration. As there is no dedicated reset signal
	* wired up for MX6QDL, we need to manually force LTSSM into "detect"
	* state before completely disabling LTSSM, which is a prerequisite
	* for core configuration.
	*
	* If both LTSSM_ENABLE and REF_SSP_ENABLE are active we have a strong
	* indication that the bootloader activated the link.
	*/
	regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1, &gpr1);
	regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12, &gpr12);

	if ((gpr1 & IMX6Q_GPR1_PCIE_REF_CLK_EN) &&
	(gpr12 & IMX6Q_GPR12_PCIE_CTL_2)) {
	val = readl(pp->dbi_base + PCIE_PL_PFLR);
	val &= ~PCIE_PL_PFLR_LINK_STATE_MASK;
	val \|= PCIE_PL_PFLR_FORCE_LINK;
	writel(val, pp->dbi_base + PCIE_PL_PFLR);

	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
	IMX6Q_GPR12_PCIE_CTL_2, 0 << 10);
	}

	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
	IMX6Q_GPR1_PCIE_TEST_PD, 1 << 18);
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
	IMX6Q_GPR1_PCIE_REF_CLK_EN, 0 << 16);

	return 0;
	}

	static int imx6_pcie_deassert_core_reset(struct pcie_port *pp)
	{
	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
	int ret;

	ret = clk_prepare_enable(imx6_pcie->pcie_phy);
	if (ret) {
	dev_err(pp->dev, "unable to enable pcie_phy clock\n");
	goto err_pcie_phy;
	}

	ret = clk_prepare_enable(imx6_pcie->pcie_bus);
	if (ret) {
	dev_err(pp->dev, "unable to enable pcie_bus clock\n");
	goto err_pcie_bus;
	}

	ret = clk_prepare_enable(imx6_pcie->pcie);
	if (ret) {
	dev_err(pp->dev, "unable to enable pcie clock\n");
	goto err_pcie;
	}

	/* power up core phy and enable ref clock */
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
	IMX6Q_GPR1_PCIE_TEST_PD, 0 << 18);
	/*
	* the async reset input need ref clock to sync internally,
	* when the ref clock comes after reset, internal synced
	* reset time is too short, cannot meet the requirement.
	* add one ~10us delay here.
	*/
	udelay(10);
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
	IMX6Q_GPR1_PCIE_REF_CLK_EN, 1 << 16);

	/* allow the clocks to stabilize */
	usleep_range(200, 500);

	/* Some boards don't have PCIe reset GPIO. */
	if (gpio_is_valid(imx6_pcie->reset_gpio)) {
	gpio_set_value(imx6_pcie->reset_gpio, 0);
	msleep(100);
	gpio_set_value(imx6_pcie->reset_gpio, 1);
	}
	return 0;

	err_pcie:
	clk_disable_unprepare(imx6_pcie->pcie_bus);
	err_pcie_bus:
	clk_disable_unprepare(imx6_pcie->pcie_phy);
	err_pcie_phy:
	return ret;

	}

	static void imx6_pcie_init_phy(struct pcie_port *pp)
	{
	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);

	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
	IMX6Q_GPR12_PCIE_CTL_2, 0 << 10);

	/* configure constant input signal to the pcie ctrl and phy */
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
	IMX6Q_GPR12_DEVICE_TYPE, PCI_EXP_TYPE_ROOT_PORT << 12);
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
	IMX6Q_GPR12_LOS_LEVEL, 9 << 4);

	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
	IMX6Q_GPR8_TX_DEEMPH_GEN1, 0 << 0);
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
	IMX6Q_GPR8_TX_DEEMPH_GEN2_3P5DB, 0 << 6);
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
	IMX6Q_GPR8_TX_DEEMPH_GEN2_6DB, 20 << 12);
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
	IMX6Q_GPR8_TX_SWING_FULL, 127 << 18);
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
	IMX6Q_GPR8_TX_SWING_LOW, 127 << 25);
	}

	static int imx6_pcie_wait_for_link(struct pcie_port *pp)
	{
	unsigned int retries;

	for (retries = 0; retries < 200; retries++) {
	if (dw_pcie_link_up(pp))
	return 0;
	usleep_range(100, 1000);
	}

	dev_err(pp->dev, "phy link never came up\n");
	dev_dbg(pp->dev, "DEBUG_R0: 0x%08x, DEBUG_R1: 0x%08x\n",
	readl(pp->dbi_base + PCIE_PHY_DEBUG_R0),
	readl(pp->dbi_base + PCIE_PHY_DEBUG_R1));
	return -EINVAL;
	}

	static int imx6_pcie_wait_for_speed_change(struct pcie_port *pp)
	{
	u32 tmp;
	unsigned int retries;

	for (retries = 0; retries < 200; retries++) {
	tmp = readl(pp->dbi_base + PCIE_LINK_WIDTH_SPEED_CONTROL);
	/* Test if the speed change finished. */
	if (!(tmp & PORT_LOGIC_SPEED_CHANGE))
	return 0;
	usleep_range(100, 1000);
	}

	dev_err(pp->dev, "Speed change timeout\n");
	return -EINVAL;
	}

	static irqreturn_t imx6_pcie_msi_handler(int irq, void *arg)
	{
	struct pcie_port *pp = arg;

	return dw_handle_msi_irq(pp);
	}

	static int imx6_pcie_establish_link(struct pcie_port *pp)
	{
	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
	u32 tmp;
	int ret;

	/*
	* Force Gen1 operation when starting the link. In case the link is
	* started in Gen2 mode, there is a possibility the devices on the
	* bus will not be detected at all. This happens with PCIe switches.
	*/
	tmp = readl(pp->dbi_base + PCIE_RC_LCR);
	tmp &= ~PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK;
	tmp \|= PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1;
	writel(tmp, pp->dbi_base + PCIE_RC_LCR);

	/* Start LTSSM. */
	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
	IMX6Q_GPR12_PCIE_CTL_2, 1 << 10);

	ret = imx6_pcie_wait_for_link(pp);
	if (ret)
	return ret;

	/* Allow Gen2 mode after the link is up. */
	tmp = readl(pp->dbi_base + PCIE_RC_LCR);
	tmp &= ~PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK;
	tmp \|= PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN2;
	writel(tmp, pp->dbi_base + PCIE_RC_LCR);

	/*
	* Start Directed Speed Change so the best possible speed both link
	* partners support can be negotiated.
	*/
	tmp = readl(pp->dbi_base + PCIE_LINK_WIDTH_SPEED_CONTROL);
	tmp \|= PORT_LOGIC_SPEED_CHANGE;
	writel(tmp, pp->dbi_base + PCIE_LINK_WIDTH_SPEED_CONTROL);

	ret = imx6_pcie_wait_for_speed_change(pp);
	if (ret) {
	dev_err(pp->dev, "Failed to bring link up!\n");
	return ret;
	}

	/* Make sure link training is finished as well! */
	ret = imx6_pcie_wait_for_link(pp);
	if (ret) {
	dev_err(pp->dev, "Failed to bring link up!\n");
	return ret;
	}

	tmp = readl(pp->dbi_base + PCIE_RC_LCSR);
	dev_dbg(pp->dev, "Link up, Gen=%i\n", (tmp >> 16) & 0xf);
	return 0;
	}

	static void imx6_pcie_host_init(struct pcie_port *pp)
	{
	imx6_pcie_assert_core_reset(pp);

	imx6_pcie_init_phy(pp);

	imx6_pcie_deassert_core_reset(pp);

	dw_pcie_setup_rc(pp);

	imx6_pcie_establish_link(pp);

	if (IS_ENABLED(CONFIG_PCI_MSI))
	dw_pcie_msi_init(pp);
	}

	static void imx6_pcie_reset_phy(struct pcie_port *pp)
	{
	u32 tmp;

	pcie_phy_read(pp->dbi_base, PHY_RX_OVRD_IN_LO, &tmp);
	tmp \|= (PHY_RX_OVRD_IN_LO_RX_DATA_EN \|
	PHY_RX_OVRD_IN_LO_RX_PLL_EN);
	pcie_phy_write(pp->dbi_base, PHY_RX_OVRD_IN_LO, tmp);

	usleep_range(2000, 3000);

	pcie_phy_read(pp->dbi_base, PHY_RX_OVRD_IN_LO, &tmp);
	tmp &= ~(PHY_RX_OVRD_IN_LO_RX_DATA_EN \|
	PHY_RX_OVRD_IN_LO_RX_PLL_EN);
	pcie_phy_write(pp->dbi_base, PHY_RX_OVRD_IN_LO, tmp);
	}

	static int imx6_pcie_link_up(struct pcie_port *pp)
	{
	u32 rc, debug_r0, rx_valid;
	int count = 5;

	/*
	* Test if the PHY reports that the link is up and also that the LTSSM
	* training finished. There are three possible states of the link when
	* this code is called:
	* 1) The link is DOWN (unlikely)
	* The link didn't come up yet for some reason. This usually means
	* we have a real problem somewhere. Reset the PHY and exit. This
	* state calls for inspection of the DEBUG registers.
	* 2) The link is UP, but still in LTSSM training
	* Wait for the training to finish, which should take a very short
	* time. If the training does not finish, we have a problem and we
	* need to inspect the DEBUG registers. If the training does finish,
	* the link is up and operating correctly.
	* 3) The link is UP and no longer in LTSSM training
	* The link is up and operating correctly.
	*/
	while (1) {
	rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
	if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP))
	break;
	if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
	return 1;
	if (!count--)
	break;
	dev_dbg(pp->dev, "Link is up, but still in training\n");
	/*
	* Wait a little bit, then re-check if the link finished
	* the training.
	*/
	usleep_range(1000, 2000);
	}
	/*
	* From L0, initiate MAC entry to gen2 if EP/RC supports gen2.
	* Wait 2ms (LTSSM timeout is 24ms, PHY lock is ~5us in gen2).
	* If (MAC/LTSSM.state == Recovery.RcvrLock)
	* && (PHY/rx_valid==0) then pulse PHY/rx_reset. Transition
	* to gen2 is stuck
	*/
	pcie_phy_read(pp->dbi_base, PCIE_PHY_RX_ASIC_OUT, &rx_valid);
	debug_r0 = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0);

	if (rx_valid & 0x01)
	return 0;

	if ((debug_r0 & 0x3f) != 0x0d)
	return 0;

	dev_err(pp->dev, "transition to gen2 is stuck, reset PHY!\n");
	dev_dbg(pp->dev, "debug_r0=%08x debug_r1=%08x\n", debug_r0, rc);

	imx6_pcie_reset_phy(pp);

	return 0;
	}

	static struct pcie_host_ops imx6_pcie_host_ops = {
	.link_up = imx6_pcie_link_up,
	.host_init = imx6_pcie_host_init,
	};

	static int __init imx6_add_pcie_port(struct pcie_port *pp,
	struct platform_device *pdev)
	{
	int ret;

	if (IS_ENABLED(CONFIG_PCI_MSI)) {
	pp->msi_irq = platform_get_irq_byname(pdev, "msi");
	if (pp->msi_irq <= 0) {
	dev_err(&pdev->dev, "failed to get MSI irq\n");
	return -ENODEV;
	}

	ret = devm_request_irq(&pdev->dev, pp->msi_irq,
	imx6_pcie_msi_handler,
	IRQF_SHARED, "mx6-pcie-msi", pp);
	if (ret) {
	dev_err(&pdev->dev, "failed to request MSI irq\n");
	return -ENODEV;
	}
	}

	pp->root_bus_nr = -1;
	pp->ops = &imx6_pcie_host_ops;

	ret = dw_pcie_host_init(pp);
	if (ret) {
	dev_err(&pdev->dev, "failed to initialize host\n");
	return ret;
	}

	return 0;
	}

	static int __init imx6_pcie_probe(struct platform_device *pdev)
	{
	struct imx6_pcie *imx6_pcie;
	struct pcie_port *pp;
	struct device_node *np = pdev->dev.of_node;
	struct resource *dbi_base;
	int ret;

	imx6_pcie = devm_kzalloc(&pdev->dev, sizeof(*imx6_pcie), GFP_KERNEL);
	if (!imx6_pcie)
	return -ENOMEM;

	pp = &imx6_pcie->pp;
	pp->dev = &pdev->dev;

	/* Added for PCI abort handling */
	hook_fault_code(16 + 6, imx6q_pcie_abort_handler, SIGBUS, 0,
	"imprecise external abort");

	dbi_base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	pp->dbi_base = devm_ioremap_resource(&pdev->dev, dbi_base);
	if (IS_ERR(pp->dbi_base))
	return PTR_ERR(pp->dbi_base);

	/* Fetch GPIOs */
	imx6_pcie->reset_gpio = of_get_named_gpio(np, "reset-gpio", 0);
	if (gpio_is_valid(imx6_pcie->reset_gpio)) {
	ret = devm_gpio_request_one(&pdev->dev, imx6_pcie->reset_gpio,
	GPIOF_OUT_INIT_LOW, "PCIe reset");
	if (ret) {
	dev_err(&pdev->dev, "unable to get reset gpio\n");
	return ret;
	}
	}

	/* Fetch clocks */
	imx6_pcie->pcie_phy = devm_clk_get(&pdev->dev, "pcie_phy");
	if (IS_ERR(imx6_pcie->pcie_phy)) {
	dev_err(&pdev->dev,
	"pcie_phy clock source missing or invalid\n");
	return PTR_ERR(imx6_pcie->pcie_phy);
	}

	imx6_pcie->pcie_bus = devm_clk_get(&pdev->dev, "pcie_bus");
	if (IS_ERR(imx6_pcie->pcie_bus)) {
	dev_err(&pdev->dev,
	"pcie_bus clock source missing or invalid\n");
	return PTR_ERR(imx6_pcie->pcie_bus);
	}

	imx6_pcie->pcie = devm_clk_get(&pdev->dev, "pcie");
	if (IS_ERR(imx6_pcie->pcie)) {
	dev_err(&pdev->dev,
	"pcie clock source missing or invalid\n");
	return PTR_ERR(imx6_pcie->pcie);
	}

	/* Grab GPR config register range */
	imx6_pcie->iomuxc_gpr =
	syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr");
	if (IS_ERR(imx6_pcie->iomuxc_gpr)) {
	dev_err(&pdev->dev, "unable to find iomuxc registers\n");
	return PTR_ERR(imx6_pcie->iomuxc_gpr);
	}

	ret = imx6_add_pcie_port(pp, pdev);
	if (ret < 0)
	return ret;

	platform_set_drvdata(pdev, imx6_pcie);
	return 0;
	}

	static void imx6_pcie_shutdown(struct platform_device *pdev)
	{
	struct imx6_pcie *imx6_pcie = platform_get_drvdata(pdev);

	/* bring down link, so bootloader gets clean state in case of reboot */
	imx6_pcie_assert_core_reset(&imx6_pcie->pp);
	}

	static const struct of_device_id imx6_pcie_of_match[] = {
	{ .compatible = "fsl,imx6q-pcie", },
	{},
	};
	MODULE_DEVICE_TABLE(of, imx6_pcie_of_match);

	static struct platform_driver imx6_pcie_driver = {
	.driver = {
	.name = "imx6q-pcie",
	.of_match_table = imx6_pcie_of_match,
	},
	.shutdown = imx6_pcie_shutdown,
	};

	/* Freescale PCIe driver does not allow module unload */

	static int __init imx6_pcie_init(void)
	{
	return platform_driver_probe(&imx6_pcie_driver, imx6_pcie_probe);
	}
	module_init(imx6_pcie_init);

	MODULE_AUTHOR("Sean Cross <xobs@kosagi.com>");
	MODULE_DESCRIPTION("Freescale i.MX6 PCIe host controller driver");
	MODULE_LICENSE("GPL v2");