Re: [RFC PATCH 5/6] PCI: designware: Add SiFive FU740 PCIe host controller driver

[Bjorn Helgaas <helgaas@kernel.org>]

Make the subject like this:

  PCI: fu740: Add SiFive FU740 PCIe host controller driver

since you're adding a "fu740" driver, not a "designware" driver.
Future commits will then look like:

  PCI: fu740: ...

On Tue, Mar 02, 2021 at 06:59:16PM +0800, Greentime Hu wrote:
> From: Paul Walmsley <paul.walmsley@sifive.com>
> 
> Add driver for the SiFive FU740 PCIe host controller.
> This controller is based on the DesignWare PCIe core.
> 
> Co-developed-by: Henry Styles <hes@sifive.com>
> Signed-off-by: Henry Styles <hes@sifive.com>
> Co-developed-by: Erik Danie <erik.danie@sifive.com>
> Signed-off-by: Erik Danie <erik.danie@sifive.com>
> Co-developed-by: Greentime Hu <greentime.hu@sifive.com>
> Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
> Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
> ---
>  drivers/pci/controller/dwc/Kconfig      |   9 +
>  drivers/pci/controller/dwc/Makefile     |   1 +
>  drivers/pci/controller/dwc/pcie-fu740.c | 455 ++++++++++++++++++++++++
>  3 files changed, 465 insertions(+)
>  create mode 100644 drivers/pci/controller/dwc/pcie-fu740.c
> 
> diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
> index 22c5529e9a65..0a37d21ed64e 100644
> --- a/drivers/pci/controller/dwc/Kconfig
> +++ b/drivers/pci/controller/dwc/Kconfig
> @@ -318,4 +318,13 @@ config PCIE_AL
>  	  required only for DT-based platforms. ACPI platforms with the
>  	  Annapurna Labs PCIe controller don't need to enable this.
>  
> +config PCIE_FU740
> +	bool "SiFive FU740 PCIe host controller"
> +	depends on PCI_MSI_IRQ_DOMAIN
> +	depends on SOC_SIFIVE || COMPILE_TEST
> +	select PCIE_DW_HOST
> +	help
> +	  Say Y here if you want PCIe controller support for the SiFive
> +	  FU740.
> +
>  endmenu
> diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
> index a751553fa0db..625f6aaeb5b8 100644
> --- a/drivers/pci/controller/dwc/Makefile
> +++ b/drivers/pci/controller/dwc/Makefile
> @@ -5,6 +5,7 @@ obj-$(CONFIG_PCIE_DW_EP) += pcie-designware-ep.o
>  obj-$(CONFIG_PCIE_DW_PLAT) += pcie-designware-plat.o
>  obj-$(CONFIG_PCI_DRA7XX) += pci-dra7xx.o
>  obj-$(CONFIG_PCI_EXYNOS) += pci-exynos.o
> +obj-$(CONFIG_PCIE_FU740) += pcie-fu740.o
>  obj-$(CONFIG_PCI_IMX6) += pci-imx6.o
>  obj-$(CONFIG_PCIE_SPEAR13XX) += pcie-spear13xx.o
>  obj-$(CONFIG_PCI_KEYSTONE) += pci-keystone.o
> diff --git a/drivers/pci/controller/dwc/pcie-fu740.c b/drivers/pci/controller/dwc/pcie-fu740.c
> new file mode 100644
> index 000000000000..6916eea40ea5
> --- /dev/null
> +++ b/drivers/pci/controller/dwc/pcie-fu740.c
> @@ -0,0 +1,455 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * FU740 DesignWare PCIe Controller integration
> + * Copyright (C) 2019-2021 SiFive, Inc.
> + * Paul Walmsley
> + * Greentime Hu
> + *
> + * Based in part on the i.MX6 PCIe host controller shim which is:
> + *
> + * Copyright (C) 2013 Kosagi
> + *		https://www.kosagi.com
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/gpio.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of_gpio.h>
> +#include <linux/of_device.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/resource.h>
> +#include <linux/signal.h>
> +#include <linux/types.h>
> +#include <linux/interrupt.h>
> +#include <linux/reset.h>
> +#include <linux/pm_domain.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "pcie-designware.h"
> +
> +#define to_fu740_pcie(x)	dev_get_drvdata((x)->dev)
> +
> +struct fu740_pcie {
> +	struct dw_pcie *pci;
> +	void __iomem *mgmt_base;
> +	int perstn_gpio;
> +	int pwren_gpio;
> +	struct clk *pcie_aux;
> +	struct reset_control *rst;
> +};
> +
> +#define SIFIVE_DEVICESRESETREG			0x28
> +
> +#define PCIEX8MGMT_PERST_N			0x0
> +#define PCIEX8MGMT_APP_LTSSM_ENABLE		0x10
> +#define PCIEX8MGMT_APP_HOLD_PHY_RST		0x18
> +#define PCIEX8MGMT_DEVICE_TYPE			0x708
> +#define PCIEX8MGMT_PHY0_CR_PARA_ADDR		0x860
> +#define PCIEX8MGMT_PHY0_CR_PARA_RD_EN		0x870
> +#define PCIEX8MGMT_PHY0_CR_PARA_RD_DATA		0x878
> +#define PCIEX8MGMT_PHY0_CR_PARA_SEL		0x880
> +#define PCIEX8MGMT_PHY0_CR_PARA_WR_DATA		0x888
> +#define PCIEX8MGMT_PHY0_CR_PARA_WR_EN		0x890
> +#define PCIEX8MGMT_PHY0_CR_PARA_ACK		0x898
> +#define PCIEX8MGMT_PHY1_CR_PARA_ADDR		0x8a0
> +#define PCIEX8MGMT_PHY1_CR_PARA_RD_EN		0x8b0
> +#define PCIEX8MGMT_PHY1_CR_PARA_RD_DATA		0x8b8
> +#define PCIEX8MGMT_PHY1_CR_PARA_SEL		0x8c0
> +#define PCIEX8MGMT_PHY1_CR_PARA_WR_DATA		0x8c8
> +#define PCIEX8MGMT_PHY1_CR_PARA_WR_EN		0x8d0
> +#define PCIEX8MGMT_PHY1_CR_PARA_ACK		0x8d8
> +
> +/* PCIe Port Logic registers (memory-mapped) */
> +#define PL_OFFSET				0x700
> +#define PCIE_PL_GEN2_CTRL_OFF			(PL_OFFSET + 0x10c)
> +#define PCIE_PL_DIRECTED_SPEED_CHANGE_OFF	0x20000
> +
> +#define PCIE_PHY_MAX_RETRY_CNT			1000
> +
> +static void fu740_pcie_assert_perstn(struct fu740_pcie *afp)
> +{
> +	/* PERST_N GPIO */
> +	if (gpio_is_valid(afp->perstn_gpio))
> +		gpio_direction_output(afp->perstn_gpio, 0);
> +
> +	/* Controller PERST_N */
> +	__raw_writel(0x0, afp->mgmt_base + PCIEX8MGMT_PERST_N);
> +}
> +
> +static void fu740_pcie_deassert_perstn(struct fu740_pcie *afp)
> +{
> +	/* Controller PERST_N */
> +	__raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_PERST_N);
> +	/* PERST_N GPIO */
> +	if (gpio_is_valid(afp->perstn_gpio))
> +		gpio_direction_output(afp->perstn_gpio, 1);
> +}
> +
> +static void fu740_pcie_power_on(struct fu740_pcie *afp)
> +{
> +	if (gpio_is_valid(afp->pwren_gpio)) {
> +		gpio_direction_output(afp->pwren_gpio, 1);
> +		mdelay(100);

Can you add a note about where the 100ms value comes from?

> +	}
> +}
> +
> +static void fu740_pcie_drive_perstn(struct fu740_pcie *afp)
> +{
> +	fu740_pcie_assert_perstn(afp);
> +	fu740_pcie_power_on(afp);
> +	fu740_pcie_deassert_perstn(afp);
> +}
> +
> +static void fu740_phyregreadwrite(const uint8_t phy, const uint8_t write,
> +				const uint16_t addr,
> +				const uint16_t wrdata, uint16_t *rddata,
> +				struct fu740_pcie *afp)
> +{
> +	unsigned char ack = 0;
> +	unsigned int cnt = 0;
> +	struct device *dev = afp->pci->dev;
> +
> +	/* setup */

Most of your single-line comments start with a capital letter.  It's
nice if they all use the same style.

> +	__raw_writel(addr,
> +		     afp->mgmt_base +
> +		     (phy ? PCIEX8MGMT_PHY1_CR_PARA_ADDR :
> +		      PCIEX8MGMT_PHY0_CR_PARA_ADDR));

All these "phy ? x : y" expressions are really ugly and maybe could be
factored out ahead of time.

> +	if (write)
> +		__raw_writel(wrdata,
> +			     afp->mgmt_base +
> +			     (phy ? PCIEX8MGMT_PHY1_CR_PARA_WR_DATA :
> +			      PCIEX8MGMT_PHY0_CR_PARA_WR_DATA));
> +	if (write)
> +		__raw_writel(1,
> +			     afp->mgmt_base +
> +			     (phy ? PCIEX8MGMT_PHY1_CR_PARA_WR_EN :
> +			      PCIEX8MGMT_PHY0_CR_PARA_WR_EN));
> +	else
> +		__raw_writel(1,
> +			     afp->mgmt_base +
> +			     (phy ? PCIEX8MGMT_PHY1_CR_PARA_RD_EN :
> +			      PCIEX8MGMT_PHY0_CR_PARA_RD_EN));
> +
> +	/* wait for wait_idle */
> +	do {
> +		if (__raw_readl
> +		    (afp->mgmt_base +
> +		     (phy ? PCIEX8MGMT_PHY1_CR_PARA_ACK :
> +		      PCIEX8MGMT_PHY0_CR_PARA_ACK))) {
> +			ack = 1;
> +			if (!write)
> +				__raw_readl(afp->mgmt_base +
> +					    (phy ?
> +					     PCIEX8MGMT_PHY1_CR_PARA_RD_DATA :
> +					     PCIEX8MGMT_PHY0_CR_PARA_RD_DATA));
> +		}
> +	} while (!ack);

Possible infinite loop.  We should try to avoid depending on hardware
doing the right thing.  If the hardware breaks or is removed, we don't
want to hang.

> +	/* clear */
> +	if (write)
> +		__raw_writel(0,
> +			     afp->mgmt_base +
> +			     (phy ? PCIEX8MGMT_PHY1_CR_PARA_WR_EN :
> +			      PCIEX8MGMT_PHY0_CR_PARA_WR_EN));
> +	else
> +		__raw_writel(0,
> +			     afp->mgmt_base +
> +			     (phy ? PCIEX8MGMT_PHY1_CR_PARA_RD_EN :
> +			      PCIEX8MGMT_PHY0_CR_PARA_RD_EN));
> +
> +	/* wait for ~wait_idle */
> +	while (__raw_readl
> +	       (afp->mgmt_base +
> +		(phy ? PCIEX8MGMT_PHY1_CR_PARA_ACK :
> +		 PCIEX8MGMT_PHY0_CR_PARA_ACK))) {
> +		cpu_relax();
> +		cnt++;
> +		if (cnt > PCIE_PHY_MAX_RETRY_CNT) {
> +			dev_err(dev, "PCIE phy doesn't enter idle state.\n");
> +			break;
> +		}
> +	}
> +}
> +
> +static void fu740_pcie_init_phy(struct fu740_pcie *afp)
> +{
> +	int lane;
> +
> +	/* enable phy cr_para_sel interfaces */
> +	__raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_PHY0_CR_PARA_SEL);
> +	__raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_PHY1_CR_PARA_SEL);
> +
> +	/* wait 10 cr_para cycles */
> +	msleep(1);

A reference to the spec section that requires the 1ms would be
helpful.

> +	/* set PHY AC termination mode */
> +	for (lane = 0; lane < 4; lane++) {
> +		fu740_phyregreadwrite(0, 1,
> +				     0x1008 + (0x100 * lane),
> +				     0x0e21, NULL, afp);
> +		fu740_phyregreadwrite(1, 1,
> +				     0x1008 + (0x100 * lane),
> +				     0x0e21, NULL, afp);

Rewrap to use more of the 80-column line.  Each will fit on two
lines.

Maybe add #defines for the 0x1008, 0x100, 0x0e21 magic numbers?  Could
compute the "0x1008 + (0x100 * lane)" expression once instead of
repeating it.

> +	}
> +
> +}
> +
> +static void fu740_pcie_ltssm_enable(struct device *dev)
> +{
> +	struct fu740_pcie *afp = dev_get_drvdata(dev);
> +
> +	/* Enable LTSSM */
> +	__raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_APP_LTSSM_ENABLE);
> +}
> +
> +static int fu740_pcie_start_link(struct dw_pcie *pci)
> +{
> +	struct device *dev = pci->dev;
> +	u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> +	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.
> +	 */
> +	dw_pcie_dbi_ro_wr_en(pci);
> +	tmp = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> +	tmp &= ~PCI_EXP_LNKCAP_SLS;
> +	tmp |= PCI_EXP_LNKCAP_SLS_2_5GB;
> +	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, tmp);
> +	dw_pcie_dbi_ro_wr_dis(pci);
> +
> +	/* Start LTSSM. */
> +	fu740_pcie_ltssm_enable(dev);
> +
> +	ret = dw_pcie_wait_for_link(pci);
> +	if (ret)
> +		goto err_reset_phy;
> +
> +	/* Now set it to operate in Gen3 */
> +	dw_pcie_dbi_ro_wr_en(pci);
> +	tmp = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> +	tmp &= ~PCI_EXP_LNKCAP_SLS;
> +	tmp |= PCI_EXP_LNKCAP_SLS_8_0GB;
> +	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, tmp);
> +	/* Enable DIRECTED SPEED CHANGE bit of GEN2_CTRL_OFF register */
> +	tmp = dw_pcie_readl_dbi(pci, PCIE_PL_GEN2_CTRL_OFF);
> +	tmp |= PCIE_PL_DIRECTED_SPEED_CHANGE_OFF;
> +	dw_pcie_writel_dbi(pci, PCIE_PL_GEN2_CTRL_OFF, tmp);
> +	dw_pcie_dbi_ro_wr_dis(pci);
> +
> +	ret = dw_pcie_wait_for_link(pci);
> +	if (ret)
> +		goto err_reset_phy;
> +
> +	/*
> +	 * Reenable DIRECTED SPEED CHANGE.
> +	 *
> +	 * You need to set this bit after each speed change, but after
> +	 * reaching G1, setting it once doesn't seem to work (it reaches G3
> +	 * equalization states and then times out, falls back to G1). But
> +	 * If after that, you set it again, it then reaches G3 perfectly

s/If after/if after/

> +	 * fine.
> +	 */
> +	dw_pcie_dbi_ro_wr_en(pci);
> +	tmp = dw_pcie_readl_dbi(pci, PCIE_PL_GEN2_CTRL_OFF);
> +	tmp |= PCIE_PL_DIRECTED_SPEED_CHANGE_OFF;
> +	dw_pcie_writel_dbi(pci, PCIE_PL_GEN2_CTRL_OFF, tmp);
> +	dw_pcie_dbi_ro_wr_dis(pci);
> +
> +	ret = dw_pcie_wait_for_link(pci);
> +	if (ret)
> +		goto err_reset_phy;
> +
> +	tmp = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
> +	dev_info(dev, "Link up, Gen%i\n", tmp & PCI_EXP_LNKSTA_CLS);
> +	return 0;
> +
> + err_reset_phy:
> +	dev_err(dev, "Failed to bring link up!\n"
> +		"PHY DEBUG_R0=0x%08x DEBUG_R1=0x%08x\n",
> +		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0),
> +		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1));
> +	return ret;
> +}
> +
> +static int fu740_pcie_host_init(struct pcie_port *pp)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	struct fu740_pcie *afp = to_fu740_pcie(pci);
> +	struct device *dev = pci->dev;
> +	int ret = 0;

Unnecessary init of "ret".

> +
> +	/* power on reset */
> +	fu740_pcie_drive_perstn(afp);
> +
> +	/* enable pcieauxclk */
> +	ret = clk_prepare_enable(afp->pcie_aux);
> +	if (ret)
> +		dev_err(dev, "unable to enable pcie_aux clock\n");
> +
> +	/*
> +	 * assert hold_phy_rst (hold the controller LTSSM in reset after
> +	 * power_up_rst_n
> +	 * for register programming with cr_para)

Rewrap text to fill lines.

> +	 */
> +	__raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_APP_HOLD_PHY_RST);
> +
> +	/* deassert power_up_rst_n */
> +	ret = reset_control_deassert(afp->rst);
> +	if (ret)
> +		dev_err(dev, "unable to deassert pcie_power_up_rst_n\n");
> +
> +	fu740_pcie_init_phy(afp);
> +
> +	/* disable pcieauxclk */
> +	clk_disable_unprepare(afp->pcie_aux);
> +	/* clear hold_phy_rst */
> +	__raw_writel(0x0, afp->mgmt_base + PCIEX8MGMT_APP_HOLD_PHY_RST);
> +	/* enable pcieauxclk */
> +	ret = clk_prepare_enable(afp->pcie_aux);
> +	/* set RC mode */
> +	__raw_writel(0x4, afp->mgmt_base + PCIEX8MGMT_DEVICE_TYPE);
> +
> +	return 0;
> +}
> +
> +static const struct dw_pcie_host_ops fu740_pcie_host_ops = {
> +	.host_init = fu740_pcie_host_init,
> +};
> +
> +static const struct dw_pcie_ops dw_pcie_ops = {
> +	.start_link = fu740_pcie_start_link,
> +};
> +
> +static const struct dev_pm_ops fu740_pcie_pm_ops = {
> +	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(fu740_pcie_suspend_noirq,
> +				      fu740_pcie_resume_noirq)

fu740_pcie_suspend_noirq() and fu740_pcie_resume_noirq() don't exist.
Am I missing something?

> +};
> +
> +static int fu740_pcie_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct dw_pcie *pci;
> +	struct fu740_pcie *afp;
> +	struct resource *mgmt_res;
> +	struct device_node *node = dev->of_node;
> +	int ret;
> +	u16 val;
> +
> +	afp = devm_kzalloc(dev, sizeof(*afp), GFP_KERNEL);
> +	if (!afp)
> +		return -ENOMEM;
> +
> +	pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
> +	if (!pci)
> +		return -ENOMEM;
> +
> +	pci->dev = dev;
> +	pci->ops = &dw_pcie_ops;
> +	pci->pp.ops = &fu740_pcie_host_ops;
> +
> +	afp->pci = pci;
> +
> +	mgmt_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mgmt");

Does every driver make up a new name for this register space?  I see
"mem", "cfg", "app", "dbics", "regs", "config", "ctrl", "dbi", "dbi2",
"addr_space", "atu", "cs", "csr", breg", "cfg", "pcireg", etc.  I know
there *are* different kinds of registers that need different names,
but I don't believe there are *this many* different kinds.  It'd be
nice if different drivers could use the same name for the same
registers.

> +	if (!mgmt_res) {
> +		dev_warn(dev, "missing required mgmt address range");
> +		return -ENOENT;
> +	}
> +	afp->mgmt_base = devm_ioremap_resource(dev, mgmt_res);
> +	if (IS_ERR(afp->mgmt_base))
> +		return PTR_ERR(afp->mgmt_base);
> +
> +	/* Fetch GPIOs */
> +	afp->perstn_gpio = of_get_named_gpio(node, "perstn-gpios", 0);
> +	if (gpio_is_valid(afp->perstn_gpio)) {
> +		ret = devm_gpio_request_one(dev, afp->perstn_gpio,
> +					    GPIOF_OUT_INIT_LOW, "perstn-gpios");
> +		if (ret) {
> +			dev_err(dev, "unable to get perstn gpio\n");

Maybe make the message match the DT property, i.e., "perstn-gpios"?

> +			return ret;
> +		}
> +	} else if (afp->perstn_gpio == -EPROBE_DEFER) {
> +		dev_err(dev, "perst-gpios EPROBE_DEFER\n");
> +		return afp->perstn_gpio;
> +	}

This structure is a little awkward, partly because it makes the implicit
assumption that -EPROBE_DEFER is not a valid GPIO number.  I think
this structure would be better:

  afp->perstn_gpio = of_get_named_gpio(...);
  if (afp->perstn_gpio == -EPROBE_DEFER)
    return perstn_gpio;

  if (gpio_is_valid(afp->perstn_gpio)) {
    ret = devm_gpio_request_one(...);
    if (ret)
      return ret;
  }

Also, similar code in mvebu_pcie_parse_port() suggests that
devm_gpio_request_one() itself can return -EPROBE_DEFER, which seems
to be true.  I have no idea whether you want to do anything special
with -EPROBE_DEFER in that case here.

> +	afp->pwren_gpio = of_get_named_gpio(node, "pwren-gpios", 0);
> +	if (gpio_is_valid(afp->pwren_gpio)) {
> +		ret = devm_gpio_request_one(dev, afp->pwren_gpio,
> +					    GPIOF_OUT_INIT_LOW, "pwren-gpios");
> +		if (ret) {
> +			dev_err(dev, "unable to get pwren gpio\n");
> +			return ret;
> +		}
> +	} else if (afp->pwren_gpio == -EPROBE_DEFER) {
> +		dev_err(dev, "pwren-gpios EPROBE_DEFER\n");
> +		return afp->pwren_gpio;
> +	}
> +
> +	/* Fetch clocks */
> +	afp->pcie_aux = devm_clk_get(dev, "pcie_aux");
> +	if (IS_ERR(afp->pcie_aux))
> +		return dev_err_probe(dev, PTR_ERR(afp->pcie_aux),
> +					     "pcie_aux clock source missing or invalid\n");
> +
> +	/* Fetch reset */
> +	afp->rst = devm_reset_control_get(dev, NULL);
> +	if (IS_ERR(afp->rst))
> +		return dev_err_probe(dev, PTR_ERR(afp->rst), "unable to get reset\n");
> +
> +	platform_set_drvdata(pdev, afp);
> +
> +	ret = dw_pcie_host_init(&pci->pp);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (pci_msi_enabled()) {
> +		u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
> +
> +		val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
> +		val |= PCI_MSI_FLAGS_ENABLE;
> +		dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
> +	}
> +
> +	return 0;
> +}
> +
> +static void fu740_pcie_shutdown(struct platform_device *pdev)
> +{
> +	struct fu740_pcie *afp = platform_get_drvdata(pdev);
> +
> +	/* bring down link, so bootloader gets clean state in case of reboot */
> +	fu740_pcie_assert_perstn(afp);
> +}
> +
> +static const struct of_device_id fu740_pcie_of_match[] = {
> +	{.compatible = "sifive,fu740-pcie"},

Typically there are a couple spaces inserted here, i.e.,

  { .compatible = "sifive,fu740-pcie", },

> +	{},
> +};
> +
> +static struct platform_driver fu740_pcie_driver = {
> +	.driver = {
> +		   .name = "fu740-pcie",
> +		   .of_match_table = fu740_pcie_of_match,
> +		   .suppress_bind_attrs = true,
> +		   .pm = &fu740_pcie_pm_ops,
> +		   },

Typical indentation would remove a tab before the "}".  Match other
drivers.

> +	.probe = fu740_pcie_probe,
> +	.shutdown = fu740_pcie_shutdown,
> +};
> +
> +static int __init fu740_pcie_init(void)
> +{
> +	return platform_driver_register(&fu740_pcie_driver);
> +}
> +
> +device_initcall(fu740_pcie_init);

pci-imx6.c is the only other driver that uses device_initcall().

Use builtin_platform_driver() or similar if possible, as other drivers
do.