Message-ID: <c5715abea71d8988b542216804c35853de168e9a.camel@baylibre.com>
Date:   Tue, 14 Aug 2018 12:41:14 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Hanjie Lin <hanjie.lin@...ogic.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Yue Wang <yue.wang@...ogic.com>,
        Kevin Hilman <khilman@...libre.com>,
        Rob Herring <robh@...nel.org>, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH 2/2] PCI: meson: add the Amlogic Meson PCIe controller
 driver

On Tue, 2018-08-14 at 02:18 -0400, Hanjie Lin wrote:
> From: Yue Wang <yue.wang@...ogic.com>
> 
> The Amlogic Meson PCIe host controller is based on the Synopsys DesignWare
> PCI core. This patch adds the driver support for Meson PCIe controller.
> 
> Signed-off-by: Yue Wang <yue.wang@...ogic.com>
> Signed-off-by: Hanjie Lin <hanjie.lin@...ogic.com>
> ---
>  drivers/pci/controller/dwc/Kconfig     |  12 +
>  drivers/pci/controller/dwc/Makefile    |   1 +
>  drivers/pci/controller/dwc/pci-meson.c | 588 +++++++++++++++++++++++++++++++++
>  3 files changed, 601 insertions(+)
>  create mode 100644 drivers/pci/controller/dwc/pci-meson.c
> 
> diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
> index 91b0194..6cb36f6 100644
> --- a/drivers/pci/controller/dwc/Kconfig
> +++ b/drivers/pci/controller/dwc/Kconfig
> @@ -193,4 +193,16 @@ config PCIE_HISI_STB
>  	help
>            Say Y here if you want PCIe controller support on HiSilicon STB SoCs
>  
> +config PCI_MESON
> +	bool "MESON PCIe controller"
> +	depends on PCI
> +	depends on PCI_MSI_IRQ_DOMAIN
> +	select PCIEPORTBUS
> +	select PCIE_DW_HOST
> +	help
> +	  Say Y here if you want to enable PCI controller support on Amlogic
> +	  SoCs. The PCI controller on Amlogic is based on DesignWare hardware
> +	  and therefore the driver re-uses the DesignWare core functions to
> +	  implement the driver.
> +
>  endmenu
> diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
> index 5d2ce72..cf676bd 100644
> --- a/drivers/pci/controller/dwc/Makefile
> +++ b/drivers/pci/controller/dwc/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_PCIE_ARMADA_8K) += pcie-armada8k.o
>  obj-$(CONFIG_PCIE_ARTPEC6) += pcie-artpec6.o
>  obj-$(CONFIG_PCIE_KIRIN) += pcie-kirin.o
>  obj-$(CONFIG_PCIE_HISI_STB) += pcie-histb.o
> +obj-$(CONFIG_PCI_MESON) += pci-meson.o
>  
>  # The following drivers are for devices that use the generic ACPI
>  # pci_root.c driver but don't support standard ECAM config access.
> diff --git a/drivers/pci/controller/dwc/pci-meson.c b/drivers/pci/controller/dwc/pci-meson.c
> new file mode 100644
> index 0000000..1e96e45
> --- /dev/null
> +++ b/drivers/pci/controller/dwc/pci-meson.c
> @@ -0,0 +1,588 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * PCIe host controller driver for Amlogic MESON SoCs
> + *
> + * Copyright (c) 2018 Amlogic, inc.
> + * Author: Yue Wang <yue.wang@...ogic.com>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/of_device.h>
> +#include <linux/of_gpio.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/phy/phy.h>
> +#include <linux/resource.h>
> +#include <linux/types.h>
> +
> +#include "pcie-designware.h"
> +
> +#define to_meson_pcie(x) dev_get_drvdata((x)->dev)
> +
> +/* External local bus interface registers */
> +#define PLR_OFFSET			0x700
> +#define PCIE_PORT_LINK_CTRL_OFF		(PLR_OFFSET + 0x10)
> +#define FAST_LINK_MODE			BIT(7)
> +#define LINK_CAPABLE_MASK		GENMASK(21, 16)
> +#define LINK_CAPABLE_X1			BIT(16)
> +
> +#define PCIE_GEN2_CTRL_OFF		(PLR_OFFSET + 0x10c)
> +#define NUM_OF_LANES_MASK		GENMASK(12, 8)
> +#define NUM_OF_LANES_X1			BIT(8)
> +#define DIRECT_SPEED_CHANGE		BIT(17)
> +
> +#define TYPE1_HDR_OFFSET		0x0
> +#define PCIE_STATUS_COMMAND		(TYPE1_HDR_OFFSET + 0x04)
> +#define PCI_IO_EN			BIT(0)
> +#define PCI_MEM_SPACE_EN		BIT(1)
> +#define PCI_BUS_MASTER_EN		BIT(2)
> +
> +#define PCIE_BASE_ADDR0			(TYPE1_HDR_OFFSET + 0x10)
> +#define PCIE_BASE_ADDR1			(TYPE1_HDR_OFFSET + 0x14)
> +
> +#define PCIE_CAP_OFFSET			0x70
> +#define PCIE_DEV_CTRL_DEV_STUS		(PCIE_CAP_OFFSET + 0x08)
> +#define PCIE_CAP_MAX_PAYLOAD_MASK	GENMASK(7, 5)
> +#define PCIE_CAP_MAX_PAYLOAD_SIZE(x)	((x) << 5)
> +#define PCIE_CAP_MAX_READ_REQ_MASK	GENMASK(14, 12)
> +#define PCIE_CAP_MAX_READ_REQ_SIZE(x)	((x) << 12)
> +
> +#define PCI_CLASS_REVISION_MASK		GENMASK(7, 0)
> +
> +/* PCIe specific config registers */
> +#define PCIE_CFG0			0x0
> +#define APP_LTSSM_ENABLE		BIT(7)
> +
> +#define PCIE_CFG_STATUS12		0x30
> +#define IS_SMLH_LINK_UP(x)		((x) & (1 << 6) ? 1 : 0)
> +#define IS_RDLH_LINK_UP(x)		((x) & (1 << 16) ? 1 : 0)
> +#define IS_LTSSM_UP(x)			((((x) >> 10) & 0x1f) == 0x11 ? 1 : 0)

those ternary ops are overkill

> +
> +#define PCIE_CFG_STATUS17		0x44
> +#define PM_CURRENT_STATE(x)		(((x) >> 7) & 0x1)
> +
> +#define WAIT_LINKUP_TIMEOUT		2000
> +#define PORT_CLK_RATE			100000000UL
> +#define MAX_PAYLOAD_SIZE		256
> +#define MAX_READ_REQ_SIZE		256
> +
> +enum pcie_data_rate {
> +	PCIE_GEN1,
> +	PCIE_GEN2,
> +	PCIE_GEN3,
> +	PCIE_GEN4
> +};
> +
> +struct meson_pcie_mem_res {
> +	void __iomem *elbi_base; /* DT 0th resource */
> +	void __iomem *cfg_base; /* DT 2nd resource */
> +};
> +
> +struct meson_pcie_clk_res {
> +	struct clk *clk;
> +	struct clk *mipi_gate;
> +	struct clk *port_clk;
> +	struct clk *general_clk;
> +};
> +
> +struct meson_pcie {
> +	struct dw_pcie pci;
> +	struct meson_pcie_mem_res mem_res;
> +	struct meson_pcie_clk_res clk_res;
> +	int reset_gpio;
> +
> +	struct phy *phy;
> +	enum of_gpio_flags gpio_flag;
> +	int pcie_num;
> +	u32 port_num;
> +	u32 device_attch;
> +};
> +
> +static int meson_pcie_get_mem(struct platform_device *pdev,
> +			      struct meson_pcie *mp)
> +{
> +	struct device *dev = mp->pci.dev;
> +	struct resource *res;
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "elbi");
> +	if (!res)
> +		return -ENODEV;
> +
> +	mp->mem_res.elbi_base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(mp->mem_res.elbi_base))
> +		return PTR_ERR(mp->mem_res.elbi_base);
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "cfg");
> +	if (!res)
> +		return -ENODEV;
> +
> +	mp->mem_res.cfg_base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(mp->mem_res.cfg_base))
> +		return PTR_ERR(mp->mem_res.cfg_base);
> +
> +	return 0;
> +}
> +
> +static int meson_pcie_init_clk(struct meson_pcie *mp)
> +{
> +	struct device *dev = mp->pci.dev;
> +	struct meson_pcie_clk_res *res = &mp->clk_res;
> +	int ret;
> +
> +	res->port_clk = devm_clk_get(dev, "port");
> +	if (IS_ERR(res->port_clk)) {
> +		if (PTR_ERR(res->port_clk) != -EPROBE_DEFER)
> +			dev_err(dev, "Failed to get pcie port clock\n");
> +
> +		return PTR_ERR(res->port_clk);
> +	}
> +
> +	res->mipi_gate = devm_clk_get(dev, "pcie_mipi_en");
> +	if (IS_ERR(res->mipi_gate)) {
> +		if (PTR_ERR(res->mipi_gate) != -EPROBE_DEFER)
> +			dev_err(dev, "Failed to get pcie mipi clock\n");
> +
> +		return PTR_ERR(res->mipi_gate);
> +	}
> +
> +	res->general_clk = devm_clk_get(dev, "pcie_general");
> +	if (IS_ERR(res->general_clk)) {
> +		if (PTR_ERR(res->general_clk) != -EPROBE_DEFER)
> +			dev_err(dev, "Failed to get pcie general clock\n");
> +
> +		return PTR_ERR(res->general_clk);
> +	}
> +
> +	res->clk = devm_clk_get(dev, "pcie");
> +	if (IS_ERR(res->clk)) {
> +		if (PTR_ERR(res->clk) != -EPROBE_DEFER)
> +			dev_err(dev, "Failed to get pcie rc clock\n");
> +
> +		return PTR_ERR(res->clk);
> +	}
> +
> +	phy_init(mp->phy);
> +
> +	ret = clk_set_rate(res->port_clk, PORT_CLK_RATE);
> +	if (ret) {
> +		dev_err(dev, "set bus clk rate failed, ret = %d", ret);
> +		goto err_clk;
> +	}
> +
> +	ret = clk_prepare_enable(res->port_clk);
> +	if (ret) {
> +		dev_err(dev, "cannot enable pcie port clock");
> +		goto err_clk;
> +	}
> +
> +	ret = clk_prepare_enable(res->mipi_gate);
> +	if (ret) {
> +		dev_err(dev, "cannot enable pcie mipi gate clock");
> +		goto err_port_clk;
> +	}
> +
> +	ret = clk_prepare_enable(res->general_clk);
> +	if (ret) {
> +		dev_err(dev, "cannot enable pcie general clock");
> +		goto err_mipi_gate;
> +	}
> +
> +	ret = clk_prepare_enable(res->clk);
> +	if (ret) {
> +		dev_err(dev, "cannot enable pcie rc clock");
> +		goto err_general_clk;
> +	}
> +
> +	return 0;
> +
> +err_general_clk:
> +	clk_disable_unprepare(res->general_clk);
> +err_mipi_gate:
> +	clk_disable_unprepare(res->mipi_gate);
> +err_port_clk:
> +	clk_disable_unprepare(res->port_clk);
> +err_clk:
> +	return ret;
> +}
> +
> +static void meson_pcie_deinit_clk(struct meson_pcie *mp)
> +{
> +	clk_disable_unprepare(mp->clk_res.clk);
> +	clk_disable_unprepare(mp->clk_res.general_clk);
> +	clk_disable_unprepare(mp->clk_res.mipi_gate);
> +	clk_disable_unprepare(mp->clk_res.port_clk);
> +}
> +
> +static inline void meson_elb_writel(struct meson_pcie *mp, u32 val, u32 reg)
> +{
> +	writel(val, mp->mem_res.elbi_base + reg);
> +}
> +
> +static inline u32 meson_elb_readl(struct meson_pcie *mp, u32 reg)
> +{
> +	return readl(mp->mem_res.elbi_base + reg);
> +}
> +
> +static inline u32 meson_cfg_readl(struct meson_pcie *mp, u32 reg)
> +{
> +	return readl(mp->mem_res.cfg_base + reg);
> +}
> +
> +static inline void meson_cfg_writel(struct meson_pcie *mp, u32 val, u32 reg)
> +{
> +	writel(val, mp->mem_res.cfg_base + reg);
> +}
> +
> +static void meson_pcie_assert_reset(struct meson_pcie *mp)
> +{
> +	int val;
> +
> +	if (!(gpio_is_valid(mp->reset_gpio)))
> +		return;

if you use devm_gpiod_get() to get the gpio, this is not required

> +
> +	if (mp->gpio_flag & OF_GPIO_OPEN_DRAIN) {
> +		val = mp->gpio_flag & OF_GPIO_ACTIVE_LOW ? 1 : 0;

handling active low should be up to gpiolib ... not open coded

> +		gpio_direction_output(mp->reset_gpio, val);
> +		udelay(500);
> +		gpio_direction_input(mp->reset_gpio);
> +	} else {
> +		val = mp->gpio_flag & OF_GPIO_ACTIVE_LOW ? 1 : 0;
> +		gpio_set_value_cansleep(mp->reset_gpio, val);
> +		udelay(500);
> +		val = mp->gpio_flag & OF_GPIO_ACTIVE_LOW ? 0 : 1;
> +		gpio_set_value_cansleep(mp->reset_gpio, val);
> +	}

I'm a bit puzzled by this. Should this OPEN_DRAIN thing be handled in the
GPIO/PINCTRL driver ?

> +}
> +
> +static void meson_pcie_init_dw(struct meson_pcie *mp)
> +{
> +	u32 val = 0;
> +
> +	val = meson_cfg_readl(mp, PCIE_CFG0);
> +	val |= APP_LTSSM_ENABLE;
> +	meson_cfg_writel(mp, val, PCIE_CFG0);
> +
> +	val = meson_elb_readl(mp, PCIE_PORT_LINK_CTRL_OFF);
> +	val &= ~LINK_CAPABLE_MASK;
> +	meson_elb_writel(mp, val, PCIE_PORT_LINK_CTRL_OFF);
> +
> +	val = meson_elb_readl(mp, PCIE_PORT_LINK_CTRL_OFF);
> +	val |= LINK_CAPABLE_X1 | FAST_LINK_MODE;
> +	meson_elb_writel(mp, val, PCIE_PORT_LINK_CTRL_OFF);
> +
> +	val = meson_elb_readl(mp, PCIE_GEN2_CTRL_OFF);
> +	val &= ~NUM_OF_LANES_MASK;
> +	meson_elb_writel(mp, val, PCIE_GEN2_CTRL_OFF);
> +
> +	val = meson_elb_readl(mp, PCIE_GEN2_CTRL_OFF);
> +	val |= NUM_OF_LANES_X1 | DIRECT_SPEED_CHANGE;
> +	meson_elb_writel(mp, val, PCIE_GEN2_CTRL_OFF);
> +
> +	meson_elb_writel(mp, 0x0, PCIE_BASE_ADDR0);
> +	meson_elb_writel(mp, 0x0, PCIE_BASE_ADDR1);
> +}
> +
> +static int meson_size_to_payload(int size)
> +{
> +	if (size & (size - 1) || size < 128 || size > 4096)
> +		return 1;
> +
> +	return fls(size) - 8;
> +}
> +
> +static void meson_set_max_payload(struct meson_pcie *mp, int size)
> +{
> +	u32 val = 0;
> +	int max_payload_size = meson_size_to_payload(size);
> +
> +	val = meson_elb_readl(mp, PCIE_DEV_CTRL_DEV_STUS);
> +	val &= ~PCIE_CAP_MAX_PAYLOAD_MASK;
> +	meson_elb_writel(mp, val, PCIE_DEV_CTRL_DEV_STUS);
> +
> +	val = meson_elb_readl(mp, PCIE_DEV_CTRL_DEV_STUS);
> +	val |= PCIE_CAP_MAX_PAYLOAD_SIZE(max_payload_size);
> +	meson_elb_writel(mp, val, PCIE_DEV_CTRL_DEV_STUS);
> +}
> +
> +static void meson_set_max_rd_req_size(struct meson_pcie *mp, int size)
> +{
> +	u32 val = 0;
> +	int max_rd_req_size = meson_size_to_payload(size);
> +
> +	val = meson_elb_readl(mp, PCIE_DEV_CTRL_DEV_STUS);
> +	val &= ~PCIE_CAP_MAX_READ_REQ_MASK;
> +	meson_elb_writel(mp, val, PCIE_DEV_CTRL_DEV_STUS);
> +
> +	val = meson_elb_readl(mp, PCIE_DEV_CTRL_DEV_STUS);
> +	val |= PCIE_CAP_MAX_READ_REQ_SIZE(max_rd_req_size);
> +	meson_elb_writel(mp, val, PCIE_DEV_CTRL_DEV_STUS);
> +}
> +
> +static inline void meson_enable_memory_space(struct meson_pcie *mp)
> +{
> +	/* Set the RC Bus Master, Memory Space and I/O Space enables */
> +	meson_elb_writel(mp, PCI_IO_EN | PCI_MEM_SPACE_EN | PCI_BUS_MASTER_EN,
> +			 PCIE_STATUS_COMMAND);
> +}
> +
> +static int meson_pcie_establish_link(struct meson_pcie *mp)
> +{
> +	struct dw_pcie *pci = &mp->pci;
> +	struct pcie_port *pp = &pci->pp;
> +
> +	meson_pcie_init_dw(mp);
> +	meson_set_max_payload(mp, MAX_PAYLOAD_SIZE);
> +	meson_set_max_rd_req_size(mp, MAX_READ_REQ_SIZE);
> +
> +	dw_pcie_setup_rc(pp);
> +	meson_enable_memory_space(mp);
> +
> +	meson_pcie_assert_reset(mp);
> +
> +	/* check if the link is up or not */
> +	if (!dw_pcie_wait_for_link(pci))
> +		return 0;
> +
> +	return -ETIMEDOUT;
> +}
> +
> +static void meson_pcie_msi_init(struct meson_pcie *mp)
> +{
> +	struct pcie_port *pp = &mp->pci.pp;
> +
> +	dw_pcie_msi_init(pp);
> +}
> +
> +static void meson_pcie_enable_interrupts(struct meson_pcie *mp)
> +{
> +	if (IS_ENABLED(CONFIG_PCI_MSI))
> +		meson_pcie_msi_init(mp);
> +}
> +
> +static u32 meson_pcie_read_dbi(struct dw_pcie *pci, void __iomem *base,
> +			       u32 reg, size_t size)
> +{
> +	u32 val;
> +
> +	dw_pcie_read(base + reg, size, &val);
> +
> +	return val;
> +}
> +
> +static void meson_pcie_write_dbi(struct dw_pcie *pci, void __iomem *base,
> +				 u32 reg, size_t size, u32 val)
> +{
> +	dw_pcie_write(base + reg, size, val);
> +}
> +
> +static int meson_pcie_rd_own_conf(struct pcie_port *pp, int where, int size,
> +				  u32 *val)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	struct meson_pcie *mp = to_meson_pcie(pci);
> +
> +	if (!mp->device_attch)
> +		return 0;
> +
> +	/* the device class is not reported correctly from the register */
> +	if (where == PCI_CLASS_REVISION) {
> +		*val = readl(pci->dbi_base + PCI_CLASS_REVISION);
> +		/* keep revision id */
> +		*val &= PCI_CLASS_REVISION_MASK;
> +		*val |= PCI_CLASS_BRIDGE_PCI << 16;
> +		return PCIBIOS_SUCCESSFUL;
> +	}
> +
> +	return dw_pcie_read(pci->dbi_base + where, size, val);
> +}
> +
> +static int meson_pcie_wr_own_conf(struct pcie_port *pp, int where,
> +				  int size, u32 val)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	struct meson_pcie *mp = to_meson_pcie(pci);
> +
> +	if (!mp->device_attch)
> +		return 0;
> +
> +	return dw_pcie_write(pci->dbi_base + where, size, val);
> +}
> +
> +static int meson_pcie_link_up(struct dw_pcie *pci)
> +{
> +	struct meson_pcie *mp = to_meson_pcie(pci);
> +	struct device *dev = pci->dev;
> +	u32 smlh_up = 0;
> +	u32 ltssm_up = 0;
> +	u32 rdlh_up = 0;
> +	u32 speed_okay = 0;
> +	u32 cnt = 0;
> +	u32 state12, state17;
> +
> +	while (smlh_up == 0 || rdlh_up == 0 || ltssm_up == 0 ||
> +	       speed_okay == 0) {
> +		udelay(20);
> +
> +		state12 = meson_cfg_readl(mp, PCIE_CFG_STATUS12);
> +		state17 = meson_cfg_readl(mp, PCIE_CFG_STATUS17);
> +		smlh_up = IS_SMLH_LINK_UP(state12);
> +		rdlh_up = IS_RDLH_LINK_UP(state12);
> +		ltssm_up = IS_LTSSM_UP(state12);
> +
> +		if (PM_CURRENT_STATE(state17) < PCIE_GEN3)
> +			speed_okay = 1;
> +
> +		if (smlh_up)
> +			dev_dbg(dev, "smlh_link_up is on\n");
> +		if (rdlh_up)
> +			dev_dbg(dev, "rdlh_link_up is on\n");
> +		if (ltssm_up)
> +			dev_dbg(dev, "ltssm_up is on\n");
> +		if (speed_okay)
> +			dev_dbg(dev, "speed_okay\n");
> +
> +		cnt++;
> +
> +		if (cnt >= WAIT_LINKUP_TIMEOUT) {
> +			dev_err(dev, "Error: Wait linkup timeout.\n");
> +			return 0;
> +		}
> +	}
> +
> +	return 1;
> +}
> +
> +static int meson_pcie_host_init(struct pcie_port *pp)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	struct meson_pcie *mp = to_meson_pcie(pci);
> +	int ret;
> +
> +	ret = meson_pcie_establish_link(mp);
> +
> +	if (ret)
> +		return ret;
> +
> +	mp->device_attch = 1;
> +	meson_pcie_enable_interrupts(mp);
> +
> +	return 0;
> +}
> +
> +static const struct dw_pcie_host_ops meson_pcie_host_ops = {
> +	.rd_own_conf = meson_pcie_rd_own_conf,
> +	.wr_own_conf = meson_pcie_wr_own_conf,
> +	.host_init = meson_pcie_host_init,
> +};
> +
> +static int meson_add_pcie_port(struct meson_pcie *mp,
> +			       struct platform_device *pdev)
> +{
> +	struct dw_pcie *pci = &mp->pci;
> +	struct pcie_port *pp = &pci->pp;
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	if (IS_ENABLED(CONFIG_PCI_MSI)) {
> +		pp->msi_irq = platform_get_irq(pdev, 0);
> +		if (pp->msi_irq < 0) {
> +			dev_err(dev, "failed to get msi irq\n");
> +			return pp->msi_irq;
> +		}
> +	}
> +
> +	pp->root_bus_nr = -1;
> +	pp->ops = &meson_pcie_host_ops;
> +	pci->dbi_base = mp->mem_res.elbi_base;
> +
> +	ret = dw_pcie_host_init(pp);
> +	if (ret) {
> +		dev_err(dev, "failed to initialize host\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct dw_pcie_ops dw_pcie_ops = {
> +	.read_dbi = meson_pcie_read_dbi,
> +	.write_dbi = meson_pcie_write_dbi,
> +	.link_up = meson_pcie_link_up,
> +};
> +
> +static int meson_pcie_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct dw_pcie *pci;
> +	struct meson_pcie *mp;
> +	int ret;
> +
> +	mp = devm_kzalloc(dev, sizeof(*mp), GFP_KERNEL);
> +	if (!mp)
> +		return -ENOMEM;
> +
> +	pci = &mp->pci;
> +	pci->dev = dev;
> +	pci->ops = &dw_pcie_ops;
> +
> +	mp->reset_gpio = of_get_named_gpio_flags(np, "reset-gpio", 0,
> +						 &mp->gpio_flag);
> +	if (mp->reset_gpio >= 0)
> +		devm_gpio_request(dev, mp->reset_gpio, "RESET");

devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);


> +
> +	if (of_property_read_u32(np, "pcie-num", &mp->pcie_num))
> +		dev_err(dev, "Get pcie-num failed, set default %d\n",
> +			mp->pcie_num);

What's the use of this ?

> +
> +	mp->phy = devm_of_phy_get(dev, np, NULL);
> +	if (IS_ERR(mp->phy)) {
> +		if (PTR_ERR(mp->phy) != -EPROBE_DEFER)
> +			dev_err(dev, "Get phy failed, set default %ld\n",
> +				PTR_ERR(mp->phy));
> +
> +		return PTR_ERR(mp->phy);
> +	}
> +
> +	phy_power_on(mp->phy);
> +
> +	ret = meson_pcie_init_clk(mp);
> +	if (ret) {
> +		dev_err(dev, "Init clock resources failed, %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = meson_pcie_get_mem(pdev, mp);
> +	if (ret) {
> +		dev_err(dev, "Get memory resource failed, %d\n", ret);
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, mp);
> +
> +	ret = meson_add_pcie_port(mp, pdev);
> +	if (ret < 0) {
> +		dev_err(dev, "Add PCIE port failed, %d\n", ret);
> +		meson_pcie_deinit_clk(mp);
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct of_device_id meson_pcie_of_match[] = {
> +	{
> +		.compatible = "amlogic,axg-pcie",
> +	},
> +	{},
> +};
> +
> +static struct platform_driver meson_pcie_driver = {
> +	.probe = meson_pcie_probe,
> +	.driver = {
> +		.name = "meson-pcie",
> +		.of_match_table = meson_pcie_of_match,
> +	},
> +};
> +
> +builtin_platform_driver(meson_pcie_driver);

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