Date:   Mon, 6 Mar 2023 19:24:28 +0100
From:   Emil Renner Berthing <kernel@...il.dk>
To:     Minda Chen <minda.chen@...rfivetech.com>
Cc:     Pawel Laszczak <pawell@...ence.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Chen <peter.chen@...nel.org>,
        Roger Quadros <rogerq@...nel.org>,
        Aswath Govindraju <a-govindraju@...com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH 2/3] usb: cdns3: add StarFive JH7110 USB glue layer

On Mon, 6 Mar 2023 at 10:53, Minda Chen <minda.chen@...rfivetech.com> wrote:
>
> There is a Cadence USB3 core for JH7110 SoCs, the cdns
> core is the child for this glue layer device.
>
> Signed-off-by: Minda Chen <minda.chen@...rfivetech.com>
> ---
>  MAINTAINERS                        |   7 +
>  drivers/usb/cdns3/Kconfig          |  11 +
>  drivers/usb/cdns3/Makefile         |   1 +
>  drivers/usb/cdns3/cdns3-starfive.c | 399 +++++++++++++++++++++++++++++
>  4 files changed, 418 insertions(+)
>  create mode 100644 drivers/usb/cdns3/cdns3-starfive.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ee21213d4388..2a9e89922cad 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19957,6 +19957,13 @@ M:     William Qiu <william.qiu@...rfivetech.com>
>  S:     Supported
>  F:     Documentation/devicetree/bindings/soc/starfive/jh7110-syscon.yaml
>
> +STARFIVE JH71X0 USB PHY DRIVERS
> +M:     Emil Renner Berthing <kernel@...il.dk>
> +M:     Minda Chen <minda.chen@...rfivetech.com>
> +S:     Maintained
> +F:     Documentation/devicetree/bindings/phy/starfive,jh7110-usb*.yaml
> +F:     drivers/usb/cdns3/cdns3-starfive.c
> +
>  STATIC BRANCH/CALL
>  M:     Peter Zijlstra <peterz@...radead.org>
>  M:     Josh Poimboeuf <jpoimboe@...nel.org>
> diff --git a/drivers/usb/cdns3/Kconfig b/drivers/usb/cdns3/Kconfig
> index b98ca0a1352a..a0b0a2c5430b 100644
> --- a/drivers/usb/cdns3/Kconfig
> +++ b/drivers/usb/cdns3/Kconfig
> @@ -78,6 +78,17 @@ config USB_CDNS3_IMX
>
>           For example, imx8qm and imx8qxp.
>
> +config USB_CDNS3_STARFIVE
> +       tristate "Cadence USB3 support on StarFive SoC platforms"
> +       depends on SOC_STARFIVE || COMPILE_TEST || USB_CDNS3

This entry is already under "if USB_CDNS3" and SOC_STARFIVE will
become ARCH_STARFIVE in 6.3, so
depends ARCH_STARFIVE || COMPILE_TEST

> +       help
> +         Say 'Y' or 'M' here if you are building for StarFive SoCs
> +         platforms that contain Cadence USB3 controller core.
> +
> +         e.g. JH7110.
> +
> +         If you choose to build this driver as module it will
> +         be dynamically linked and module will be called cdns3-starfive.ko
>  endif
>
>  if USB_CDNS_SUPPORT
> diff --git a/drivers/usb/cdns3/Makefile b/drivers/usb/cdns3/Makefile
> index 61edb2f89276..48dfae75b5aa 100644
> --- a/drivers/usb/cdns3/Makefile
> +++ b/drivers/usb/cdns3/Makefile
> @@ -24,6 +24,7 @@ endif
>  obj-$(CONFIG_USB_CDNS3_PCI_WRAP)               += cdns3-pci-wrap.o
>  obj-$(CONFIG_USB_CDNS3_TI)                     += cdns3-ti.o
>  obj-$(CONFIG_USB_CDNS3_IMX)                    += cdns3-imx.o
> +obj-$(CONFIG_USB_CDNS3_STARFIVE)               += cdns3-starfive.o
>
>  cdnsp-udc-pci-y                                        := cdnsp-pci.o
>
> diff --git a/drivers/usb/cdns3/cdns3-starfive.c b/drivers/usb/cdns3/cdns3-starfive.c
> new file mode 100644
> index 000000000000..54d9978cfa59
> --- /dev/null
> +++ b/drivers/usb/cdns3/cdns3-starfive.c
> @@ -0,0 +1,399 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/**
> + * cdns-starfive.c - StarFive specific Glue layer for Cadence USB Controller
> + *
> + * Copyright (C) 2022 Starfive, Inc.
> + * Author:     yanhong <yanhong.wang@...rfivetech.com>

Here their name is "yanhong", but below it's "YanHong Wang". I'm
guessing the 2nd version is correct, but please make sure.

> + * Author:     Mason Huo <mason.huo@...rfivetech.com>
> + * Author:     Minda Chen <minda.chen@...rfivetech.com>
> + */
> +
> +#include <linux/bits.h>
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/io.h>
> +#include <linux/of_platform.h>
> +#include <linux/regmap.h>
> +#include <linux/reset.h>
> +#include <linux/usb/otg.h>
> +#include "core.h"
> +
> +#define USB_STRAP_HOST                 BIT(17)
> +#define USB_STRAP_DEVICE               BIT(18)
> +#define USB_STRAP_MASK                 GENMASK(18, 16)
> +
> +#define USB_SUSPENDM_HOST              BIT(19)
> +#define USB_SUSPENDM_DEVICE            (0 << 19)
> +#define USB_SUSPENDM_MASK              BIT(19)
> +
> +#define USB_SUSPENDM_BYPS              BIT(20)
> +#define USB_REFCLK_MODE                        BIT(23)
> +#define USB_PLL_EN                     BIT(22)
> +#define USB_PDRSTN_SPLIT               BIT(17)
> +
> +#define PCIE_CKREF_SRC_MASK            GENMASK(19, 18)
> +#define PCIE_CLK_SEL_MASK              GENMASK(21, 20)
> +#define PCIE_PHY_MODE                  BIT(20)
> +#define PCIE_PHY_MODE_MASK             GENMASK(21, 20)
> +#define PCIE_USB3_BUS_WIDTH_MASK       GENMASK(3, 2)
> +#define PCIE_USB3_RATE_MASK            GENMASK(6, 5)
> +#define PCIE_USB3_RX_STANDBY_MASK      BIT(7)
> +#define PCIE_USB3_PHY_ENABLE           BIT(4)
> +#define PCIE_USB3_PHY_PLL_CTL_OFF      (0x1f * 4)
> +
> +#define USB_125M_CLK_RATE              125000000
> +
> +#define USB_LS_KEEPALIVE_OFF           0x4
> +#define USB_LS_KEEPALIVE_ENABLE                BIT(4)
> +
> +#define USB3_DOWN_SS_MODE              BIT(4)
> +
> +struct cdns_starfive {
> +       struct device *dev;
> +       struct regmap *stg_syscon;
> +       struct regmap *sys_syscon;
> +       struct reset_control *resets;
> +       struct clk_bulk_data *clks;
> +       int num_clks;
> +       struct clk *usb_125m_clk;
> +       u32 sys_offset;
> +       u32 stg_offset_4;
> +       u32 stg_offset_196;
> +       u32 stg_offset_328;
> +       u32 stg_offset_500;
> +       bool usb2_only;
> +       enum usb_dr_mode mode;
> +       void __iomem *phybase_20;
> +       void __iomem *phybase_30;
> +};
> +
> +static int cdns_mode_init(struct platform_device *pdev,
> +                               struct cdns_starfive *data)
> +{
> +       enum usb_dr_mode mode;
> +
> +       /* Init usb 2.0 utmi phy */
> +       regmap_update_bits(data->stg_syscon, data->stg_offset_4,
> +               USB_SUSPENDM_BYPS, USB_SUSPENDM_BYPS);
> +       regmap_update_bits(data->stg_syscon, data->stg_offset_4,
> +               USB_PLL_EN, USB_PLL_EN);
> +       regmap_update_bits(data->stg_syscon, data->stg_offset_4,
> +               USB_REFCLK_MODE, USB_REFCLK_MODE);
> +
> +       if (data->usb2_only) {
> +               /* Disconnect usb 3.0 phy mode */
> +               regmap_update_bits(data->sys_syscon, data->sys_offset,
> +                       USB_PDRSTN_SPLIT, USB_PDRSTN_SPLIT);
> +       } else {
> +               /* Config usb 3.0 pipe phy */
> +               regmap_update_bits(data->stg_syscon, data->stg_offset_196,
> +                       PCIE_CKREF_SRC_MASK, 0);
> +               regmap_update_bits(data->stg_syscon, data->stg_offset_196,
> +                       PCIE_CLK_SEL_MASK, 0);
> +               regmap_update_bits(data->stg_syscon, data->stg_offset_328,
> +                       PCIE_PHY_MODE_MASK, PCIE_PHY_MODE);
> +               regmap_update_bits(data->stg_syscon, data->stg_offset_500,
> +                       PCIE_USB3_BUS_WIDTH_MASK, 0);
> +               regmap_update_bits(data->stg_syscon, data->stg_offset_500,
> +                       PCIE_USB3_RATE_MASK, 0);
> +               regmap_update_bits(data->stg_syscon, data->stg_offset_500,
> +                       PCIE_USB3_RX_STANDBY_MASK, 0);
> +               regmap_update_bits(data->stg_syscon, data->stg_offset_500,
> +                       PCIE_USB3_PHY_ENABLE, PCIE_USB3_PHY_ENABLE);
> +
> +               /* Connect usb 3.0 phy mode */
> +               regmap_update_bits(data->sys_syscon, data->sys_offset,
> +                       USB_PDRSTN_SPLIT, 0);
> +       }
> +       mode = usb_get_dr_mode(&pdev->dev);
> +       data->mode = mode;
> +
> +       switch (mode) {
> +       case USB_DR_MODE_HOST:
> +               regmap_update_bits(data->stg_syscon,
> +                       data->stg_offset_4,
> +                       USB_STRAP_MASK,
> +                       USB_STRAP_HOST);
> +               regmap_update_bits(data->stg_syscon,
> +                       data->stg_offset_4,
> +                       USB_SUSPENDM_MASK,
> +                       USB_SUSPENDM_HOST);
> +               break;
> +
> +       case USB_DR_MODE_PERIPHERAL:
> +               regmap_update_bits(data->stg_syscon, data->stg_offset_4,
> +                       USB_STRAP_MASK, USB_STRAP_DEVICE);
> +               regmap_update_bits(data->stg_syscon, data->stg_offset_4,
> +                       USB_SUSPENDM_MASK, USB_SUSPENDM_DEVICE);
> +               break;
> +
> +       case USB_DR_MODE_UNKNOWN:
> +       case USB_DR_MODE_OTG:
> +       default:
> +               break;
> +       }
> +
> +       return 0;
> +}
> +
> +
> +static int cdns_clk_rst_init(struct cdns_starfive *data)
> +{
> +       int ret;
> +
> +       data->usb_125m_clk = devm_clk_get(data->dev, "usb_125m");
> +       if (IS_ERR(data->usb_125m_clk)) {
> +               dev_err(data->dev, "Failed to get usb 125m clock\n");
> +               ret = PTR_ERR(data->usb_125m_clk);
> +               goto exit;
> +       }

This can be
if (IS_ERR(data->usb_125m_clk))
  return dev_err_probe(data->dev, PTR_ERR(data->usb_125m_clk), "Failed
to get usb 125m clock\n");

This will also silence errors on -EPROBE_DEFER.

> +
> +       data->num_clks = devm_clk_bulk_get_all(data->dev, &data->clks);
> +       if (data->num_clks < 0) {
> +               dev_err(data->dev, "Failed to get usb clocks\n");
> +               ret = -ENODEV;
> +               goto exit;
> +       }

Again return dev_err_probe(data->dev, -ENODEV, ..

> +
> +       /* Needs to set the USB_125M clock explicitly,
> +        * since it's divided from pll0 clock, and the pll0 clock
> +        * changes per the cpu frequency.
> +        */
> +       ret = clk_set_rate(data->usb_125m_clk, USB_125M_CLK_RATE);
> +       if (ret) {
> +               dev_err(data->dev, "Failed to set usb 125m clock\n");
> +               goto exit;
> +       }

return dev_err_probe

> +       ret = clk_bulk_prepare_enable(data->num_clks, data->clks);
> +       if (ret) {
> +               dev_err(data->dev, "Failed to enable clocks\n");
> +               goto exit;
> +       }

return dev_err_probe

> +
> +       data->resets = devm_reset_control_array_get_exclusive(data->dev);
> +       if (IS_ERR(data->resets)) {
> +               ret = PTR_ERR(data->resets);
> +               dev_err(data->dev, "Failed to get usb resets");
> +               goto err_clk_init;
> +       }

This can be
ret = dev_err_probe(data->dev, PTR_ERR(data->resets), ..)
goto err_clk_init;

> +       ret = reset_control_deassert(data->resets);

This is where the driver fails for me, but the only place you don't
write why. Add return dev_err_probe to be consistent.

> +       goto exit;
> +
> +err_clk_init:
> +       clk_bulk_disable_unprepare(data->num_clks, data->clks);
> +exit:
> +       return ret;
> +}
> +
> +static void cdns_starfive_set_phy(struct cdns_starfive *data)
> +{
> +       unsigned int val;
> +
> +       if (data->mode != USB_DR_MODE_PERIPHERAL) {
> +               /* Enable the LS speed keep-alive signal */
> +               val = readl(data->phybase_20 + USB_LS_KEEPALIVE_OFF);
> +               val |= USB_LS_KEEPALIVE_ENABLE;
> +               writel(val, data->phybase_20 + USB_LS_KEEPALIVE_OFF);
> +       }
> +
> +       if (!data->usb2_only) {
> +               /* Configuare spread-spectrum mode: down-spread-spectrum */
> +               writel(USB3_DOWN_SS_MODE, data->phybase_30 + PCIE_USB3_PHY_PLL_CTL_OFF);
> +       }
> +}
> +
> +static int cdns_starfive_phy_init(struct platform_device *pdev,
> +                                                       struct cdns_starfive *data)
> +{
> +       struct device *dev = &pdev->dev;
> +       int ret = 0;
> +
> +       data->phybase_20 = devm_platform_ioremap_resource_byname(pdev, "usb2");
> +       if (IS_ERR(data->phybase_20)) {
> +               dev_err(dev, "Can't map phybase_20 IOMEM resource\n");
> +               ret = PTR_ERR(data->phybase_20);
> +               goto get_res_err;
> +       }

return dev_err_probe(dev, PTR_ERROR(...

> +
> +       data->phybase_30 = devm_platform_ioremap_resource_byname(pdev, "usb3");
> +       if (IS_ERR(data->phybase_30)) {
> +               dev_err(dev, "Can't map phybase_30 IOMEM resource\n");
> +               ret = PTR_ERR(data->phybase_30);
> +               goto get_res_err;
> +       }

return dev_err_probe

> +
> +       cdns_starfive_set_phy(data);
> +
> +get_res_err:
> +       return ret;

now this can just be return 0;

> +}
> +
> +static int cdns_starfive_probe(struct platform_device *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct device_node *node = pdev->dev.of_node;
> +       struct cdns_starfive *data;
> +       struct of_phandle_args args;
> +       int ret;
> +
> +       data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +       if (!data)
> +               return -ENOMEM;
> +
> +       platform_set_drvdata(pdev, data);
> +
> +       data->dev = dev;
> +
> +       data->usb2_only = device_property_read_bool(dev, "starfive,usb2-only");
> +       ret = of_parse_phandle_with_fixed_args(pdev->dev.of_node,
> +                                               "starfive,stg-syscon", 4, 0, &args);

This looks like syscon_regmap_lookup_by_phandle_args

> +       if (ret < 0) {
> +               dev_err(dev, "Failed to parse starfive,stg-syscon\n");
> +               return -EINVAL;
> +       }

return dev_err_probe(dev, ret, ..

> +       data->stg_syscon = syscon_node_to_regmap(args.np);
> +       of_node_put(args.np);
> +       if (IS_ERR(data->stg_syscon))
> +               return PTR_ERR(data->stg_syscon);
> +       data->stg_offset_4 = args.args[0];
> +       data->stg_offset_196 = args.args[1];
> +       data->stg_offset_328 = args.args[2];
> +       data->stg_offset_500 = args.args[3];
> +
> +       ret = of_parse_phandle_with_fixed_args(pdev->dev.of_node,
> +                                               "starfive,sys-syscon", 1, 0, &args);

syscon_regmap_lookup_by_phandle_args

> +       if (ret < 0) {
> +               dev_err(dev, "Failed to parse starfive,sys-syscon\n");
> +               return -EINVAL;
> +       }
> +
> +       data->sys_syscon = syscon_node_to_regmap(args.np);
> +       of_node_put(args.np);
> +       if (IS_ERR(data->sys_syscon))
> +               return PTR_ERR(data->sys_syscon);
> +       data->sys_offset = args.args[0];
> +
> +       cdns_mode_init(pdev, data);
> +
> +       ret = cdns_clk_rst_init(data);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "Failed to init usb clk reset: %d\n", ret);
> +               goto exit;
> +       }

cdns_clk_rst_init already logs errors, so just
if (ret)
  return ret;

> +       ret = cdns_starfive_phy_init(pdev, data);
> +       if (ret) {
> +               dev_err(dev, "Failed to init sratfive usb phy: %d\n", ret);
> +               goto exit;
> +       }

if (ret)
  return ret;

> +       ret = of_platform_populate(node, NULL, NULL, dev);
> +       if (ret) {
> +               dev_err(dev, "Failed to create children: %d\n", ret);
> +               goto exit;
> +       }

return dev_err_probe(dev, ret, "Failed to create children\n")

> +       device_set_wakeup_capable(dev, true);
> +       pm_runtime_set_active(dev);
> +       pm_runtime_enable(dev);
> +
> +       dev_info(dev, "usb mode %d %s probe success\n",
> +               data->mode, data->usb2_only ? "2.0" : "3.0");
> +
> +       return 0;
> +exit:
> +       return ret;
> +}
> +
> +static int cdns_starfive_remove_core(struct device *dev, void *c)
> +{
> +       struct platform_device *pdev = to_platform_device(dev);
> +
> +       platform_device_unregister(pdev);
> +
> +       return 0;
> +}
> +
> +static int cdns_starfive_remove(struct platform_device *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct cdns_starfive *data = dev_get_drvdata(dev);
> +
> +       pm_runtime_get_sync(dev);
> +       device_for_each_child(dev, NULL, cdns_starfive_remove_core);
> +
> +       reset_control_assert(data->resets);
> +       clk_bulk_disable_unprepare(data->num_clks, data->clks);
> +       pm_runtime_disable(dev);
> +       pm_runtime_put_noidle(dev);
> +       platform_set_drvdata(pdev, NULL);
> +
> +       return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int cdns_starfive_resume(struct device *dev)
> +{
> +       struct cdns_starfive *data = dev_get_drvdata(dev);
> +       int ret;
> +
> +       ret = clk_set_rate(data->usb_125m_clk, USB_125M_CLK_RATE);
> +       if (ret)
> +               goto err;

return ret;

> +
> +       ret = clk_bulk_prepare_enable(data->num_clks, data->clks);
> +       if (ret)
> +               goto err;

return ret;

> +       ret = reset_control_deassert(data->resets);
> +       if (ret)
> +               goto err;

return ret;
> +       cdns_starfive_set_phy(data);
> +err:
> +       return ret;
now this can just be return 0;
> +}
> +
> +static int cdns_starfive_suspend(struct device *dev)
> +{
> +       struct cdns_starfive *data = dev_get_drvdata(dev);
> +
> +       clk_bulk_disable_unprepare(data->num_clks, data->clks);
> +       reset_control_assert(data->resets);
> +
> +       return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops cdns_starfive_pm_ops = {
> +       SET_RUNTIME_PM_OPS(cdns_starfive_suspend, cdns_starfive_resume, NULL)
> +       SET_SYSTEM_SLEEP_PM_OPS(cdns_starfive_suspend, cdns_starfive_resume)
> +};
> +
> +static const struct of_device_id cdns_starfive_of_match[] = {
> +       { .compatible = "starfive,jh7110-usb", },
> +       {},

I like the idiom of using { /* sentinel */ } here

> +};
> +MODULE_DEVICE_TABLE(of, cdns_starfive_of_match);
> +
> +static struct platform_driver cdns_starfive_driver = {
> +       .probe          = cdns_starfive_probe,
> +       .remove         = cdns_starfive_remove,
> +       .driver         = {
> +               .name   = "cdns3-starfive",
> +               .of_match_table = cdns_starfive_of_match,
> +               .pm     = &cdns_starfive_pm_ops,
> +       },
> +};
> +

Empty line not needed like above.

> +module_platform_driver(cdns_starfive_driver);
> +
> +MODULE_ALIAS("platform:cdns3-starfive");
> +MODULE_AUTHOR("YanHong Wang <yanhong.wang@...rfivetech.com>");
> +MODULE_AUTHOR("Mason Huo <mason.huo@...rfivetech.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Cadence USB3 StarFive Glue Layer");
> --
> 2.17.1
>

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