Re: [PATCH v3 2/3] usb: dwc3: add common driver to support flattened DT

Ze Huang
2025-05-21T14:42:09Z

On Mon, May 19, 2025 at 11:37:35PM +0000, Thinh Nguyen wrote:
> On Sun, May 18, 2025, Ze Huang wrote:
> > To support flattened dwc3 dt model and drop the glue layer, introduce the
> > `dwc3-common` driver. This enables direct binding of the DWC3 core driver
> > and offers an alternative to the existing glue driver `dwc3-of-simple`.
> >
> > Signed-off-by: Ze Huang <huangze@whut.edu.cn>
> > ---
> > drivers/usb/dwc3/Kconfig | 9 ++
> > drivers/usb/dwc3/Makefile | 1 +
> > drivers/usb/dwc3/dwc3-common.c | 191 +++++++++++++++++++++++++++++++++++++++++
>
> Let's rename the dwc3-common to dwc3-generic-plat. I'd associate
> "common" to common code that exists in all drivers; where as this is
> mainly for generic platform driver.
>

You're right, will do.

> > 3 files changed, 201 insertions(+)
> >
> > diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig
> > index 310d182e10b50b253d7e5a51674806e6ec442a2a..852f94f906e4f339dcbb562e1ce708409ba77b76 100644
> > --- a/drivers/usb/dwc3/Kconfig
> > +++ b/drivers/usb/dwc3/Kconfig
> > @@ -118,6 +118,15 @@ config USB_DWC3_OF_SIMPLE
> > Currently supports Xilinx and Qualcomm DWC USB3 IP.
> > Say 'Y' or 'M' if you have one such device.
> >
> > +config USB_DWC3_COMMON
>
> Let's rename to USB_DWC3_GENERIC_PLAT.

Will do

> I would expect to also have USB_DWC3_GENERIC_PCI at some point in the future.
>
> Side note: flattened driver for PCI driver will allow the dwc3
> host controllers to take advantage of MSIX interrupts going through the
> dwc3 code path.
>

Thanks for pointing that out.

I don’t have a convenient setup to test PCI-based DWC3 controllers by the time,
but I’ll definitely look into it when the opportunity arises.

>
> > + tristate "DWC3 Platform common Driver"
> > + depends on OF && COMMON_CLK
> > + default USB_DWC3
> > + help
> > + Support USB3 functionality in simple SoC integrations.
> > + Currently supports SpacemiT DWC USB3 IP.
> > + Say 'Y' or 'M' if you have one such device.
> > +
> > config USB_DWC3_ST
> > tristate "STMicroelectronics Platforms"
> > depends on (ARCH_STI || COMPILE_TEST) && OF
> > diff --git a/drivers/usb/dwc3/Makefile b/drivers/usb/dwc3/Makefile
> > index 830e6c9e5fe073c1f662ce34b6a4a2da34c407a2..ad1b0705c4d464f19e79ed0c3c63d942446e4742 100644
> > --- a/drivers/usb/dwc3/Makefile
> > +++ b/drivers/usb/dwc3/Makefile
> > @@ -57,3 +57,4 @@ obj-$(CONFIG_USB_DWC3_IMX8MP) += dwc3-imx8mp.o
> > obj-$(CONFIG_USB_DWC3_XILINX) += dwc3-xilinx.o
> > obj-$(CONFIG_USB_DWC3_OCTEON) += dwc3-octeon.o
> > obj-$(CONFIG_USB_DWC3_RTK) += dwc3-rtk.o
> > +obj-$(CONFIG_USB_DWC3_COMMON) += dwc3-common.o
> > diff --git a/drivers/usb/dwc3/dwc3-common.c b/drivers/usb/dwc3/dwc3-common.c
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..afd9a7bec14b68dfd4f2353d714041882660a1a4
> > --- /dev/null
> > +++ b/drivers/usb/dwc3/dwc3-common.c
> > @@ -0,0 +1,191 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * dwc3-common.c - DesignWare USB3 common driver
> > + *
> > + * Copyright (C) 2025 Ze Huang <huangze@whut.edu.cn>
> > + *
> > + * Inspired by dwc3-qcom.c and dwc3-of-simple.c
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/of_address.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/reset.h>
> > +#include "glue.h"
> > +
> > +struct dwc3_common {
> > + struct device *dev;
> > + struct dwc3 dwc;
> > + struct clk_bulk_data *clks;
> > + int num_clocks;
> > + struct reset_control *resets;
> > +};
> > +
> > +static int dwc3_common_probe(struct platform_device *pdev)
> > +{
> > + struct dwc3_probe_data probe_data = {};
> > + struct device *dev = &pdev->dev;
> > + struct dwc3_common *dwc3c;
> > + struct resource *res;
> > + int ret;
> > +
> > + dwc3c = devm_kzalloc(dev, sizeof(*dwc3c), GFP_KERNEL);
> > + if (!dwc3c)
> > + return -ENOMEM;
> > +
> > + dwc3c->dev = dev;
> > +
> > + platform_set_drvdata(pdev, dwc3c);
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + if (!res) {
> > + dev_err(&pdev->dev, "missing memory resource\n");
> > + return -ENODEV;
> > + }
> > +
> > + dwc3c->resets = of_reset_control_array_get_optional_exclusive(dev->of_node);
> > + if (IS_ERR(dwc3c->resets))
> > + return dev_err_probe(dev, PTR_ERR(dwc3c->resets), "failed to get reset\n");
> > +
> > + ret = reset_control_assert(dwc3c->resets);
> > + if (ret)
> > + return dev_err_probe(dev, ret, "failed to assert reset\n");
> > +
> > + usleep_range(10, 1000);
> > +
> > + ret = reset_control_deassert(dwc3c->resets);
> > + if (ret) {
> > + dev_err(dev, "failed to deassert reset\n");
> > + goto reset_assert;
> > + }
> > +
> > + ret = clk_bulk_get_all(dwc3c->dev, &dwc3c->clks);
> > + if (ret < 0) {
> > + dev_err(dev, "failed to get clocks\n");
> > + goto reset_assert;
> > + }
> > +
> > + dwc3c->num_clocks = ret;
> > +
> > + ret = clk_bulk_prepare_enable(dwc3c->num_clocks, dwc3c->clks);
> > + if (ret) {
> > + dev_err(dev, "failed to enable clocks\n");
> > + goto reset_assert;
> > + }
> > +
> > + dwc3c->dwc.dev = dev;
> > + probe_data.dwc = &dwc3c->dwc;
> > + probe_data.res = res;
> > + probe_data.ignore_clocks_and_resets = true;
> > + ret = dwc3_core_probe(&probe_data);
> > + if (ret) {
> > + dev_err(dev, "failed to register DWC3 Core\n");
> > + goto clk_disable;
> > + }
> > +
> > + return 0;
> > +
> > +clk_disable:
> > + clk_bulk_disable_unprepare(dwc3c->num_clocks, dwc3c->clks);
> > + clk_bulk_put_all(dwc3c->num_clocks, dwc3c->clks);
> > +
> > +reset_assert:
> > + reset_control_assert(dwc3c->resets);
> > +
> > + return ret;
> > +}
> > +
> > +static void dwc3_common_remove(struct platform_device *pdev)
> > +{
> > + struct dwc3_common *dwc3c = platform_get_drvdata(pdev);
> > +
> > + dwc3_core_remove(&dwc3c->dwc);
> > +
> > + clk_bulk_disable_unprepare(dwc3c->num_clocks, dwc3c->clks);
> > + clk_bulk_put_all(dwc3c->num_clocks, dwc3c->clks);
> > +
> > + reset_control_assert(dwc3c->resets);
> > +}
> > +
> > +#ifdef CONFIG_PM_SLEEP
>
> Use the new SYSTEM_SLEEP_PM_OPS macros and we can do away with these PM
> guards.
>

Will follow, thanks

> > +static int dwc3_common_suspend(struct device *dev)
> > +{
> > + struct dwc3_common *dwc3c = dev_get_drvdata(dev);
> > + int ret;
> > +
> > + ret = dwc3_pm_suspend(&dwc3c->dwc);
> > + if (ret)
> > + return ret;
> > +
> > + clk_bulk_disable_unprepare(dwc3c->num_clocks, dwc3c->clks);
> > +
> > + return 0;
> > +}
> > +
> > +static int dwc3_common_resume(struct device *dev)
> > +{
> > + struct dwc3_common *dwc3c = dev_get_drvdata(dev);
> > + int ret;
> > +
> > + ret = clk_bulk_prepare_enable(dwc3c->num_clocks, dwc3c->clks);
> > + if (ret)
> > + return ret;
> > +
> > + ret = dwc3_pm_resume(&dwc3c->dwc);
> > + if (ret)
> > + return ret;
> > +
> > + return 0;
> > +}
> > +
> > +static int dwc3_common_runtime_suspend(struct device *dev)
> > +{
> > + struct dwc3_common *dwc3c = dev_get_drvdata(dev);
> > +
> > + return dwc3_runtime_suspend(&dwc3c->dwc);
> > +}
> > +
> > +static int dwc3_common_runtime_resume(struct device *dev)
> > +{
> > + struct dwc3_common *dwc3c = dev_get_drvdata(dev);
> > +
> > + return dwc3_runtime_resume(&dwc3c->dwc);
> > +}
> > +
> > +static int dwc3_common_runtime_idle(struct device *dev)
> > +{
> > + struct dwc3_common *dwc3c = dev_get_drvdata(dev);
> > +
> > + return dwc3_runtime_idle(&dwc3c->dwc);
> > +}
> > +
> > +static const struct dev_pm_ops dwc3_common_dev_pm_ops = {
> > + SET_SYSTEM_SLEEP_PM_OPS(dwc3_common_suspend, dwc3_common_resume)
> > + RUNTIME_PM_OPS(dwc3_common_runtime_suspend, dwc3_common_runtime_resume,
> > + dwc3_common_runtime_idle)
> > +};
> > +#endif /* CONFIG_PM_SLEEP */
> > +
> > +static const struct of_device_id dwc3_common_of_match[] = {
> > + { .compatible = "spacemit,k1-dwc3", },
> > + { /* sentinel */ }
> > +};
> > +MODULE_DEVICE_TABLE(of, dwc3_common_of_match);
> > +
> > +static struct platform_driver dwc3_common_driver = {
> > + .probe = dwc3_common_probe,
> > + .remove = dwc3_common_remove,
> > + .driver = {
> > + .name = "dwc3-common",
> > + .of_match_table = dwc3_common_of_match,
> > +#ifdef CONFIG_PM_SLEEP
> > + .pm = &dwc3_common_dev_pm_ops,
> > +#endif /* CONFIG_PM_SLEEP */
> > + },
> > +};
> > +module_platform_driver(dwc3_common_driver);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_DESCRIPTION("DesignWare USB3 common driver");
> >
> > --
> > 2.49.0
> >
>
> Thanks for the work. Going forward, I hope more platforms will move to
> this and take advantage of this new flattened model.
>

Thanks for the feedback! Looking forward to seeing it adopted more widely :-)

> Thanks,
> Thinh