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From: Ze Huang To: Alex Elder , Ze Huang , Greg Kroah-Hartman , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Yixun Lan , Thinh Nguyen , Philipp Zabel Cc: linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-riscv@lists.infradead.org, spacemit@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 2/2] usb: dwc3: add generic driver to support flattened Message-ID: References: <20250712-dwc3_generic-v6-0-cc87737cc936@linux.dev> <20250712-dwc3_generic-v6-2-cc87737cc936@linux.dev> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT On Tue, Jul 15, 2025 at 03:50:54PM -0500, Alex Elder wrote: > On 7/12/25 2:49 AM, Ze Huang wrote: > > To support flattened dwc3 dt model and drop the glue layer, introduce the > > `dwc3-generic` driver. This enables direct binding of the DWC3 core driver > > and offers an alternative to the existing glue driver `dwc3-of-simple`. > > I'm not familiar with dwc-of-simple.c, and won't comment on > how this differs from that (or does not). > > Given you're implementing an alternative though, can you explain > in a little more detail what's different between the two? Why > would someone choose to use this driver rather than the other one? They are basically the same. dwc-generic use a plain dt node while dwc-of-simple will nest the dwc3 node as its child. Both will use dwc3_core_probe() to finish the probe process. But now we can simplify the process by just calling it, instead of calling of_platform_populate() and create another snps,dwc3 device driver. > > > > > Signed-off-by: Ze Huang > > --- > > drivers/usb/dwc3/Kconfig | 11 +++ > > drivers/usb/dwc3/Makefile | 1 + > > drivers/usb/dwc3/dwc3-generic-plat.c | 182 +++++++++++++++++++++++++++++++++++ > > 3 files changed, 194 insertions(+) > > > > diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig > > index 310d182e10b50b253d7e5a51674806e6ec442a2a..4925d15084f816d3ff92059b476ebcc799b56b51 100644 > > --- a/drivers/usb/dwc3/Kconfig > > +++ b/drivers/usb/dwc3/Kconfig > > @@ -189,4 +189,15 @@ config USB_DWC3_RTK > > or dual-role mode. > > Say 'Y' or 'M' if you have such device. > > +config USB_DWC3_GENERIC_PLAT > > + tristate "DWC3 Generic Platform Driver" > > + depends on OF && COMMON_CLK > > + default USB_DWC3 > > + help > > + Support USB3 functionality in simple SoC integrations. > > + Currently supports SpacemiT DWC USB3. Platforms using > > + dwc3-of-simple can easily switch to dwc3-generic by flattening > > + the dwc3 child node in the device tree. > > + Say 'Y' or 'M' here if your platform integrates DWC3 in a similar way. > > + > > endif > > diff --git a/drivers/usb/dwc3/Makefile b/drivers/usb/dwc3/Makefile > > index 830e6c9e5fe073c1f662ce34b6a4a2da34c407a2..96469e48ff9d189cc8d0b65e65424eae2158bcfe 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_GENERIC_PLAT) += dwc3-generic-plat.o > > diff --git a/drivers/usb/dwc3/dwc3-generic-plat.c b/drivers/usb/dwc3/dwc3-generic-plat.c > > new file mode 100644 > > index 0000000000000000000000000000000000000000..766f4cf17b6909793956f44660d3b3febad50a23 > > --- /dev/null > > +++ b/drivers/usb/dwc3/dwc3-generic-plat.c > > @@ -0,0 +1,182 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +/* > > + * dwc3-generic-plat.c - DesignWare USB3 generic platform driver > > + * > > + * Copyright (C) 2025 Ze Huang > > + * > > + * Inspired by dwc3-qcom.c and dwc3-of-simple.c > > + */ > > + > > +#include > > +#include > > +#include > > +#include "glue.h" > > + > > +struct dwc3_generic { > > + struct device *dev; > > + struct dwc3 dwc; > > + struct clk_bulk_data *clks; > > + int num_clocks; > > + struct reset_control *resets; > > +}; > > + > > +static void dwc3_generic_reset_control_assert(void *data) > > +{ > > + reset_control_assert(data); > > +} > > + > > The next function can go away. (See below.) > OK > > +static void dwc3_generic_clk_bulk_disable_unprepare(void *data) > > +{ > > + struct dwc3_generic *dwc3 = data; > > + > > + clk_bulk_disable_unprepare(dwc3->num_clocks, dwc3->clks); > > +} > > + > > +static int dwc3_generic_probe(struct platform_device *pdev) > > +{ > > + struct dwc3_probe_data probe_data = {}; > > + struct device *dev = &pdev->dev; > > + struct dwc3_generic *dwc3; > > + struct resource *res; > > + int ret; > > + > > + dwc3 = devm_kzalloc(dev, sizeof(*dwc3), GFP_KERNEL); > > + if (!dwc3) > > + return -ENOMEM; > > + > > + dwc3->dev = dev; > > + > > + platform_set_drvdata(pdev, dwc3); > > + > > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > > + if (!res) { > > + dev_err(&pdev->dev, "missing memory resource\n"); > > + return -ENODEV; > > + } > > + > > + dwc3->resets = devm_reset_control_array_get_optional_exclusive(dev); > > + if (IS_ERR(dwc3->resets)) > > + return dev_err_probe(dev, PTR_ERR(dwc3->resets), "failed to get resets\n"); > > + > > It isn't enforced on exclusive resets, but I'm pretty sure > resets are assumed to be asserted initially. > I'd like to keep it. We cannot guarantee what environment was passed in (from bootloader), right? > > + ret = reset_control_assert(dwc3->resets); > > + if (ret) > > + return dev_err_probe(dev, ret, "failed to assert resets\n"); > > + > > + ret = devm_add_action_or_reset(dev, dwc3_generic_reset_control_assert, dwc3->resets); > > + if (ret) > > + return ret; > > The re-assert shouldn't be set up unless the deassert below > succeeds. > Will move behind the deassert. > > + usleep_range(10, 1000); > > This seems like a large range. You could just do msleep(1); > Also, can you add a comment explaining why a delay is needed, > and why 1 millisecond is the right amount of time to sleep? > I will check the range with spacemit and reply soon. > > + ret = reset_control_deassert(dwc3->resets); > > + if (ret) > > + return dev_err_probe(dev, ret, "failed to deassert resets\n"); > > + > > + ret = devm_clk_bulk_get_all(dwc3->dev, &dwc3->clks); > > + if (ret < 0) > > + return dev_err_probe(dev, ret, "failed to get clocks\n"); > > Call devm_clk_bulk_get_all_enabled() instead of doing the two > steps separately here. > Will do, thanks. > -Alex > > > + dwc3->num_clocks = ret; > > + > > + ret = clk_bulk_prepare_enable(dwc3->num_clocks, dwc3->clks); > > + if (ret) > j> + return dev_err_probe(dev, ret, "failed to enable clocks\n"); > > + > > + ret = devm_add_action_or_reset(dev, dwc3_generic_clk_bulk_disable_unprepare, dwc3); > > + if (ret) > > + return ret; > > + > > + dwc3->dwc.dev = dev; > > + probe_data.dwc = &dwc3->dwc; > > + probe_data.res = res; > > + probe_data.ignore_clocks_and_resets = true; > > + ret = dwc3_core_probe(&probe_data); > > + if (ret) > > + return dev_err_probe(dev, ret, "failed to register DWC3 Core\n"); > > + > > + return 0; > > +} > > + > > +static void dwc3_generic_remove(struct platform_device *pdev) > > +{ > > + struct dwc3_generic *dwc3 = platform_get_drvdata(pdev); > > + > > + dwc3_core_remove(&dwc3->dwc); > > +} > > + > > +static int dwc3_generic_suspend(struct device *dev) > > +{ > > + struct dwc3_generic *dwc3 = dev_get_drvdata(dev); > > + int ret; > > + > > + ret = dwc3_pm_suspend(&dwc3->dwc); > > + if (ret) > > + return ret; > > + > > + clk_bulk_disable_unprepare(dwc3->num_clocks, dwc3->clks); > > + > > + return 0; > > +} > > + > > +static int dwc3_generic_resume(struct device *dev) > > +{ > > + struct dwc3_generic *dwc3 = dev_get_drvdata(dev); > > + int ret; > > + > > + ret = clk_bulk_prepare_enable(dwc3->num_clocks, dwc3->clks); > > + if (ret) > > + return ret; > > + > > + ret = dwc3_pm_resume(&dwc3->dwc); > > + if (ret) > > + return ret; > > + > > + return 0; > > +} > > + > > +static int dwc3_generic_runtime_suspend(struct device *dev) > > +{ > > + struct dwc3_generic *dwc3 = dev_get_drvdata(dev); > > + > > + return dwc3_runtime_suspend(&dwc3->dwc); > > +} > > + > > +static int dwc3_generic_runtime_resume(struct device *dev) > > +{ > > + struct dwc3_generic *dwc3 = dev_get_drvdata(dev); > > + > > + return dwc3_runtime_resume(&dwc3->dwc); > > +} > > + > > +static int dwc3_generic_runtime_idle(struct device *dev) > > +{ > > + struct dwc3_generic *dwc3 = dev_get_drvdata(dev); > > + > > + return dwc3_runtime_idle(&dwc3->dwc); > > +} > > + > > +static const struct dev_pm_ops dwc3_generic_dev_pm_ops = { > > + SYSTEM_SLEEP_PM_OPS(dwc3_generic_suspend, dwc3_generic_resume) > > + RUNTIME_PM_OPS(dwc3_generic_runtime_suspend, dwc3_generic_runtime_resume, > > + dwc3_generic_runtime_idle) > > +}; > > + > > +static const struct of_device_id dwc3_generic_of_match[] = { > > + { .compatible = "spacemit,k1-dwc3", }, > > + { /* sentinel */ } > > +}; > > +MODULE_DEVICE_TABLE(of, dwc3_generic_of_match); > > + > > +static struct platform_driver dwc3_generic_driver = { > > + .probe = dwc3_generic_probe, > > + .remove = dwc3_generic_remove, > > + .driver = { > > + .name = "dwc3-generic-plat", > > + .of_match_table = dwc3_generic_of_match, > > + .pm = pm_ptr(&dwc3_generic_dev_pm_ops), > > + }, > > +}; > > +module_platform_driver(dwc3_generic_driver); > > + > > +MODULE_LICENSE("GPL"); > > +MODULE_DESCRIPTION("DesignWare USB3 generic platform driver"); > > >