Message-ID: <ae4592d3-872a-4e47-ac71-b5a4e43d246b@oss.qualcomm.com>
Date: Mon, 8 Dec 2025 19:43:13 +0530
From: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
To: zhangsenchuan <zhangsenchuan@...incomputing.com>
Cc: bhelgaas@...gle.com, mani@...nel.org, krzk+dt@...nel.org,
        conor+dt@...nel.org, lpieralisi@...nel.org, kwilczynski@...nel.org,
        robh@...nel.org, p.zabel@...gutronix.de, jingoohan1@...il.com,
        gustavo.pimentel@...opsys.com, linux-pci@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        christian.bruel@...s.st.com, mayank.rana@....qualcomm.com,
        shradha.t@...sung.com, thippeswamy.havalige@....com,
        inochiama@...il.com, Frank.li@....com, ningyu@...incomputing.com,
        linmin@...incomputing.com, pinkesh.vaghela@...fochips.com,
        ouyanghui@...incomputing.com
Subject: Re: [PATCH v7 2/3] PCI: eic7700: Add Eswin PCIe host controller
 driver



On 12/8/2025 6:07 PM, zhangsenchuan wrote:
>
>
>> -----Original Messages-----
>> From: "Krishna Chaitanya Chundru" <krishna.chundru@....qualcomm.com>
>> Send time:Friday, 05/12/2025 20:40:53
>> To: zhangsenchuan@...incomputing.com, bhelgaas@...gle.com, mani@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, lpieralisi@...nel.org, kwilczynski@...nel.org, robh@...nel.org, p.zabel@...gutronix.de, jingoohan1@...il.com, gustavo.pimentel@...opsys.com, linux-pci@...r.kernel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, christian.bruel@...s.st.com, mayank.rana@....qualcomm.com, shradha.t@...sung.com, thippeswamy.havalige@....com, inochiama@...il.com, Frank.li@....com
>> Cc: ningyu@...incomputing.com, linmin@...incomputing.com, pinkesh.vaghela@...fochips.com, ouyanghui@...incomputing.com
>> Subject: Re: [PATCH v7 2/3] PCI: eic7700: Add Eswin PCIe host controller driver
>>
>>
>>
>> On 12/2/2025 2:34 PM, zhangsenchuan@...incomputing.com wrote:
>>> From: Senchuan Zhang <zhangsenchuan@...incomputing.com>
>>>
>>> Add driver for the Eswin EIC7700 PCIe host controller, which is based on
>>> the DesignWare PCIe core, IP revision 5.96a. The PCIe Gen.3 controller
>>> supports a data rate of 8 GT/s and 4 channels, support INTx and MSI
>>> interrupts.
>>>
>>> Signed-off-by: Yu Ning <ningyu@...incomputing.com>
>>> Signed-off-by: Yanghui Ou <ouyanghui@...incomputing.com>
>>> Signed-off-by: Senchuan Zhang <zhangsenchuan@...incomputing.com>
>>> ---
>>>    drivers/pci/controller/dwc/Kconfig        |  11 +
>>>    drivers/pci/controller/dwc/Makefile       |   1 +
>>>    drivers/pci/controller/dwc/pcie-eic7700.c | 378 ++++++++++++++++++++++
>>>    3 files changed, 390 insertions(+)
>>>    create mode 100644 drivers/pci/controller/dwc/pcie-eic7700.c
>>>
>>> diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
>>> index 519b59422b47..c837cb5947b6 100644
>>> --- a/drivers/pci/controller/dwc/Kconfig
>>> +++ b/drivers/pci/controller/dwc/Kconfig
>>> @@ -93,6 +93,17 @@ config PCIE_BT1
>>>    	  Enables support for the PCIe controller in the Baikal-T1 SoC to work
>>>    	  in host mode. It's based on the Synopsys DWC PCIe v4.60a IP-core.
>>>    
>>> +config PCIE_EIC7700
>>> +	tristate "Eswin EIC7700 PCIe controller"
>>> +	depends on ARCH_ESWIN || COMPILE_TEST
>>> +	depends on PCI_MSI
>>> +	select PCIE_DW_HOST
>>> +	help
>>> +	  Say Y here if you want PCIe controller support for the Eswin EIC7700.
>>> +	  The PCIe controller on EIC7700 is based on DesignWare hardware,
>>> +	  enables support for the PCIe controller in the EIC7700 SoC to work in
>>> +	  host mode.
>>> +
>>>    config PCI_IMX6
>>>    	bool
>>>    
>>> diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
>>> index 67ba59c02038..7c5a5186ea83 100644
>>> --- a/drivers/pci/controller/dwc/Makefile
>>> +++ b/drivers/pci/controller/dwc/Makefile
>>> @@ -6,6 +6,7 @@ obj-$(CONFIG_PCIE_DW_EP) += pcie-designware-ep.o
>>>    obj-$(CONFIG_PCIE_DW_PLAT) += pcie-designware-plat.o
>>>    obj-$(CONFIG_PCIE_AMD_MDB) += pcie-amd-mdb.o
>>>    obj-$(CONFIG_PCIE_BT1) += pcie-bt1.o
>>> +obj-$(CONFIG_PCIE_EIC7700) += pcie-eic7700.o
>>>    obj-$(CONFIG_PCI_DRA7XX) += pci-dra7xx.o
>>>    obj-$(CONFIG_PCI_EXYNOS) += pci-exynos.o
>>>    obj-$(CONFIG_PCIE_FU740) += pcie-fu740.o
>>> diff --git a/drivers/pci/controller/dwc/pcie-eic7700.c b/drivers/pci/controller/dwc/pcie-eic7700.c
>>> new file mode 100644
>>> index 000000000000..cb7cdea6a94b
>>> --- /dev/null
>>> +++ b/drivers/pci/controller/dwc/pcie-eic7700.c
>>> @@ -0,0 +1,378 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * ESWIN EIC7700 PCIe root complex driver
>>> + *
>>> + * Copyright 2025, Beijing ESWIN Computing Technology Co., Ltd.
>>> + *
>>> + * Authors: Yu Ning <ningyu@...incomputing.com>
>>> + *          Senchuan Zhang <zhangsenchuan@...incomputing.com>
>>> + *          Yanghui Ou <ouyanghui@...incomputing.com>
>>> + */
>>> +
>>> +#include <linux/interrupt.h>
>>> +#include <linux/iopoll.h>
>>> +#include <linux/module.h>
>>> +#include <linux/of.h>
>>> +#include <linux/pci.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/pm_runtime.h>
>>> +#include <linux/resource.h>
>>> +#include <linux/reset.h>
>>> +#include <linux/types.h>
>>> +
>>> +#include "pcie-designware.h"
>>> +
>>> +/* ELBI registers */
>>> +#define PCIEELBI_CTRL0_OFFSET		0x0
>>> +#define PCIEELBI_STATUS0_OFFSET		0x100
>>> +
>>> +/* LTSSM register fields */
>>> +#define PCIEELBI_APP_LTSSM_ENABLE	BIT(5)
>>> +
>>> +/* APP_HOLD_PHY_RST register fields */
>>> +#define PCIEELBI_APP_HOLD_PHY_RST	BIT(6)
>>> +
>>> +/* PM_SEL_AUX_CLK register fields */
>>> +#define PCIEELBI_PM_SEL_AUX_CLK		BIT(16)
>>> +
>>> +/* DEV_TYPE register fields */
>>> +#define PCIEELBI_CTRL0_DEV_TYPE		GENMASK(3, 0)
>>> +
>>> +/* Vendor and device ID value */
>>> +#define PCI_VENDOR_ID_ESWIN		0x1fe1
>>> +#define PCI_DEVICE_ID_ESWIN		0x2030
>>> +
>>> +#define EIC7700_NUM_RSTS		ARRAY_SIZE(eic7700_pcie_rsts)
>>> +
>>> +static const char * const eic7700_pcie_rsts[] = {
>>> +	"pwr",
>>> +	"dbi",
>>> +};
>>> +
>>> +struct eic7700_pcie_data {
>>> +	bool no_pme_handshake;
>>> +};
>>> +
>>> +struct eic7700_pcie_port {
>>> +	struct list_head list;
>>> +	struct reset_control *perst;
>>> +	int num_lanes;
>>> +};
>>> +
>>> +struct eic7700_pcie {
>>> +	struct dw_pcie pci;
>>> +	struct clk_bulk_data *clks;
>>> +	struct reset_control_bulk_data resets[EIC7700_NUM_RSTS];
>>> +	struct list_head ports;
>>> +	const struct eic7700_pcie_data *data;
>>> +	int num_clks;
>>> +};
>>> +
>>> +#define to_eic7700_pcie(x) dev_get_drvdata((x)->dev)
>>> +
>>> +static int eic7700_pcie_start_link(struct dw_pcie *pci)
>>> +{
>>> +	u32 val;
>>> +
>>> +	/* Enable LTSSM */
>>> +	val = readl_relaxed(pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
>>> +	val |= PCIEELBI_APP_LTSSM_ENABLE;
>>> +	writel_relaxed(val, pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static bool eic7700_pcie_link_up(struct dw_pcie *pci)
>>> +{
>>> +	u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
>>> +	u16 val = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
>>> +
>>> +	return val & PCI_EXP_LNKSTA_DLLLA;
>>> +}
>>> +
>>> +static int eic7700_pcie_perst_reset(struct eic7700_pcie_port *port,
>>> +				    struct eic7700_pcie *pcie)
>>> +{
>>> +	int ret;
>>> +
>>> +	ret = reset_control_assert(port->perst);
>>> +	if (ret) {
>>> +		dev_err(pcie->pci.dev, "Failed to assert PERST#\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	/* Ensure that PERST# has been asserted for at least 100 ms */
>>> +	msleep(PCIE_T_PVPERL_MS);
>>> +
>>> +	ret = reset_control_deassert(port->perst);
>>> +	if (ret) {
>>> +		dev_err(pcie->pci.dev, "Failed to deassert PERST#\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int eic7700_pcie_parse_port(struct eic7700_pcie *pcie,
>>> +				   struct device_node *node)
>>> +{
>>> +	struct device *dev = pcie->pci.dev;
>>> +	struct eic7700_pcie_port *port;
>>> +
>>> +	port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
>>> +	if (!port)
>>> +		return -ENOMEM;
>>> +
>>> +	port->perst = of_reset_control_get_exclusive(node, "perst");
>>> +	if (IS_ERR(port->perst)) {
>>> +		dev_err(dev, "Failed to get PERST# reset\n");
>>> +		return PTR_ERR(port->perst);
>>> +	}
>>> +
>>> +	/*
>>> +	 * TODO: Since the Root Port node is separated out by pcie devicetree,
>>> +	 * the DWC core initialization code can't parse the num-lanes attribute
>>> +	 * in the Root Port. Before entering the DWC core initialization code,
>>> +	 * the platform driver code parses the Root Port node. The EIC7700 only
>>> +	 * supports one Root Port node, and the num-lanes attribute is suitable
>>> +	 * for the case of one Root Rort.
>>> +	 */
>>> +	if (!of_property_read_u32(node, "num-lanes", &port->num_lanes))
>>> +		pcie->pci.num_lanes = port->num_lanes;
>>> +
>>> +	INIT_LIST_HEAD(&port->list);
>>> +	list_add_tail(&port->list, &pcie->ports);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int eic7700_pcie_parse_ports(struct eic7700_pcie *pcie)
>>> +{
>>> +	struct eic7700_pcie_port *port, *tmp;
>>> +	struct device *dev = pcie->pci.dev;
>>> +	int ret;
>>> +
>>> +	for_each_available_child_of_node_scoped(dev->of_node, of_port) {
>>> +		ret = eic7700_pcie_parse_port(pcie, of_port);
>>> +		if (ret)
>>> +			goto err_port;
>>> +	}
>>> +
>>> +	return 0;
>>> +
>>> +err_port:
>>> +	list_for_each_entry_safe(port, tmp, &pcie->ports, list)
>>> +		list_del(&port->list);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int eic7700_pcie_host_init(struct dw_pcie_rp *pp)
>>> +{
>>> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>>> +	struct eic7700_pcie *pcie = to_eic7700_pcie(pci);
>>> +	struct eic7700_pcie_port *port;
>>> +	u32 val;
>>> +	int ret;
>>> +
>>> +	pcie->num_clks = devm_clk_bulk_get_all_enabled(pci->dev, &pcie->clks);
>>> +	if (pcie->num_clks < 0)
>>> +		return dev_err_probe(pci->dev, pcie->num_clks,
>>> +				     "Failed to get pcie clocks\n");
>>> +
>>> +	/*
>>> +	 * The PWR and DBI Reset signals are respectively used to reset the
>>> +	 * PCIe controller and the DBI registers.
>>> +	 * The PERST# signal is a reset signal that simultaneously controls the
>>> +	 * PCIe controller, PHY, and Endpoint.
>>> +	 * Before configuring the PHY, the PERST# signal must first be
>>> +	 * deasserted.
>>> +	 * The external reference clock is supplied simultaneously to the PHY
>>> +	 * and EP. When the PHY is configurable, the entire chip already has
>>> +	 * stable power and reference clock.
>>> +	 * The PHY will be ready within 20ms after writing app_hold_phy_rst
>>> +	 * register of ELBI register space.
>>> +	 */
>>> +	ret = reset_control_bulk_deassert(EIC7700_NUM_RSTS, pcie->resets);
>>> +	if (ret) {
>>> +		dev_err(pcie->pci.dev, "Failed to deassert resets\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	/* Configure Root Port type */
>>> +	val = readl_relaxed(pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
>>> +	val &= ~PCIEELBI_CTRL0_DEV_TYPE;
>>> +	val |= FIELD_PREP(PCIEELBI_CTRL0_DEV_TYPE, PCI_EXP_TYPE_ROOT_PORT);
>>> +	writel_relaxed(val, pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
>>> +
>>> +	list_for_each_entry(port, &pcie->ports, list) {
>>> +		ret = eic7700_pcie_perst_reset(port, pcie);
>>> +		if (ret)
>>> +			goto err_perst;
>>> +	}
>>> +
>>> +	/* Configure app_hold_phy_rst */
>>> +	val = readl_relaxed(pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
>>> +	val &= ~PCIEELBI_APP_HOLD_PHY_RST;
>>> +	writel_relaxed(val, pci->elbi_base + PCIEELBI_CTRL0_OFFSET);
>>> +
>>> +	/* The maximum waiting time for the clock switch lock is 20ms */
>>> +	ret = readl_poll_timeout(pci->elbi_base + PCIEELBI_STATUS0_OFFSET,
>>> +				 val, !(val & PCIEELBI_PM_SEL_AUX_CLK), 1000,
>>> +				 20000);
>>> +	if (ret) {
>>> +		dev_err(pci->dev, "Timeout waiting for PM_SEL_AUX_CLK ready\n");
>>> +		goto err_phy_init;
>>> +	}
>>> +
>>> +	/*
>>> +	 * Configure ESWIN VID:DID for Root Port as the default values are
>>> +	 * invalid.
>>> +	 */
>> we need to make dbi registers writeable before this through this API
>> dw_pcie_dbi_ro_wr_en().
> Hi, Krishna Chaitanya
>
> Thank you for your comment.
> When our driver initialization starts, the BIT(0) of the
> PCIE_MISC_CONTROL_1_OFF address defaults to 1, allowing for the reading
> and writing of dbi registers.
Thanks for the info, then in that case do we need to clear it before 
enumeration?

-  Krishna Chaitanya.
>>> +	dw_pcie_writew_dbi(pci, PCI_VENDOR_ID, PCI_VENDOR_ID_ESWIN);
>>> +	dw_pcie_writew_dbi(pci, PCI_DEVICE_ID, PCI_DEVICE_ID_ESWIN);
>>> +
>>> +	return 0;
>>> +
>>> +err_phy_init:
>>> +	list_for_each_entry(port, &pcie->ports, list)
>>> +		reset_control_assert(port->perst);
>>> +err_perst:
>>> +	reset_control_bulk_assert(EIC7700_NUM_RSTS, pcie->resets);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static void eic7700_pcie_host_deinit(struct dw_pcie_rp *pp)
>>> +{
>>> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>>> +	struct eic7700_pcie *pcie = to_eic7700_pcie(pci);
>>> +	struct eic7700_pcie_port *port;
>>> +
>>> +	list_for_each_entry(port, &pcie->ports, list)
>>> +		reset_control_assert(port->perst);
>>> +	reset_control_bulk_assert(EIC7700_NUM_RSTS, pcie->resets);
>>> +	clk_bulk_disable_unprepare(pcie->num_clks, pcie->clks);
>>> +}
>>> +
>>> +static const struct dw_pcie_host_ops eic7700_pcie_host_ops = {
>>> +	.init = eic7700_pcie_host_init,
>>> +	.deinit = eic7700_pcie_host_deinit,
>>> +};
>>> +
>>> +static const struct dw_pcie_ops dw_pcie_ops = {
>>> +	.start_link = eic7700_pcie_start_link,
>>> +	.link_up = eic7700_pcie_link_up,
>>> +};
>>> +
>>> +static int eic7700_pcie_probe(struct platform_device *pdev)
>>> +{
>>> +	const struct eic7700_pcie_data *data;
>>> +	struct eic7700_pcie_port *port, *tmp;
>>> +	struct device *dev = &pdev->dev;
>>> +	struct eic7700_pcie *pcie;
>>> +	struct dw_pcie *pci;
>>> +	int ret, i;
>>> +
>>> +	data = of_device_get_match_data(dev);
>>> +	if (!data)
>>> +		return dev_err_probe(dev, -ENODATA, "OF data missing\n");
>>> +
>>> +	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
>>> +	if (!pcie)
>>> +		return -ENOMEM;
>>> +
>>> +	INIT_LIST_HEAD(&pcie->ports);
>>> +
>>> +	pci = &pcie->pci;
>>> +	pci->dev = dev;
>>> +	pci->ops = &dw_pcie_ops;
>>> +	pci->pp.ops = &eic7700_pcie_host_ops;
>>> +	pcie->data = data;
>>> +	pci->no_pme_handshake = pcie->data->no_pme_handshake;
>>> +
>>> +	for (i = 0; i < EIC7700_NUM_RSTS; i++)
>>> +		pcie->resets[i].id = eic7700_pcie_rsts[i];
>>> +
>>> +	ret = devm_reset_control_bulk_get_exclusive(dev, EIC7700_NUM_RSTS,
>>> +						    pcie->resets);
>>> +	if (ret)
>>> +		return dev_err_probe(dev, ret, "Failed to get resets\n");
>>> +
>>> +	ret = eic7700_pcie_parse_ports(pcie);
>>> +	if (ret)
>>> +		return dev_err_probe(dev, ret,
>>> +				     "Failed to parse Root Port: %d\n", ret);
>>> +
>>> +	platform_set_drvdata(pdev, pcie);
>>> +
>>> +	pm_runtime_no_callbacks(dev);
>>> +	devm_pm_runtime_enable(dev);
>>> +	ret = pm_runtime_get_sync(dev);
>>> +	if (ret < 0)
>>> +		goto err_pm_runtime_put;
>> Any specific reason why we are enabling runtime pm and doing
>> pm_runtime_get_sync()
> To avoid warnings when the driver starts, pm_runtime_get_sync()
> has been added. Warnings as follows:
>
> "pci0000:00: runtime PM trying to activate child device pci0000:00
> but parent (54000000.pcie) is not active"
>
> Kind regards,
> Senchuan Zhang
>
>>> +
>>> +	ret = dw_pcie_host_init(&pci->pp);
>>> +	if (ret) {
>>> +		dev_err(dev, "Failed to initialize host\n");
>>> +		goto err_init;
>>> +	}
>>> +
>>> +	return 0;
>>> +
>>> +err_init:
>>> +	list_for_each_entry_safe(port, tmp, &pcie->ports, list) {
>>> +		list_del(&port->list);
>>> +		reset_control_put(port->perst);
>>> +	}
>>> +err_pm_runtime_put:
>>> +	pm_runtime_put(dev);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int eic7700_pcie_suspend_noirq(struct device *dev)
>>> +{
>>> +	struct eic7700_pcie *pcie = dev_get_drvdata(dev);
>>> +
>>> +	return dw_pcie_suspend_noirq(&pcie->pci);
>>> +}
>>> +
>>> +static int eic7700_pcie_resume_noirq(struct device *dev)
>>> +{
>>> +	struct eic7700_pcie *pcie = dev_get_drvdata(dev);
>>> +
>>> +	return dw_pcie_resume_noirq(&pcie->pci);
>>> +}
>>> +
>>> +static const struct dev_pm_ops eic7700_pcie_pm_ops = {
>>> +	NOIRQ_SYSTEM_SLEEP_PM_OPS(eic7700_pcie_suspend_noirq,
>>> +				  eic7700_pcie_resume_noirq)
>>> +};
>>> +
>>> +static const struct eic7700_pcie_data eic7700_data = {
>>> +	.no_pme_handshake = true,
>>> +};
>>> +
>>> +static const struct of_device_id eic7700_pcie_of_match[] = {
>>> +	{ .compatible = "eswin,eic7700-pcie", .data = &eic7700_data },
>>> +	{},
>>> +};
>>> +
>>> +static struct platform_driver eic7700_pcie_driver = {
>>> +	.probe = eic7700_pcie_probe,
>>> +	.driver = {
>>> +		.name = "eic7700-pcie",
>>> +		.of_match_table = eic7700_pcie_of_match,
>>> +		.suppress_bind_attrs = true,
>>> +		.pm = &eic7700_pcie_pm_ops,
>>> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
>>> +	},
>>> +};
>>> +builtin_platform_driver(eic7700_pcie_driver);
>>> +
>>> +MODULE_DESCRIPTION("Eswin EIC7700 PCIe host controller driver");
>>> +MODULE_AUTHOR("Yu Ning <ningyu@...incomputing.com>");
>>> +MODULE_AUTHOR("Senchuan Zhang <zhangsenchuan@...incomputing.com>");
>>> +MODULE_AUTHOR("Yanghui Ou <ouyanghui@...incomputing.com>");
>>> +MODULE_LICENSE("GPL");

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