linux-kernel - Re: [PATCH v3 08/12] usb: dwc3: core: Expose core driver as library

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Message-ID: <Z4a+fyhInS7ETgKh@lizhi-Precision-Tower-5810>
Date: Tue, 14 Jan 2025 14:43:59 -0500
From: Frank Li <Frank.li@....com>
To: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Felipe Balbi <balbi@...nel.org>,
	Wesley Cheng <quic_wcheng@...cinc.com>,
	Saravana Kannan <saravanak@...gle.com>,
	Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 08/12] usb: dwc3: core: Expose core driver as library

On Mon, Jan 13, 2025 at 09:11:41PM -0800, Bjorn Andersson wrote:
> The DWC3 IP block is handled by three distinct device drivers: XHCI,
> DWC3 core and a platform specific (optional) DWC3 glue driver.
>
> This has resulted in, at least in the case of the Qualcomm glue, the
> presence of a number of layering violations, where the glue code either
> can't handle, or has to work around, the fact that core might not probe
> deterministically.
>
> An example of this is that the suspend path should operate slightly
> different depending on the device operating in host or peripheral mode,
> and the only way to determine the operating state is to peek into the
> core's drvdata.
>
> The Qualcomm glue driver is expected to make updates in the qscratch
> register region (the "glue" region) during role switch events, but with
> the glue and core split using the driver model, there is no reasonable
> way to introduce listeners for mode changes.
>
> Split the dwc3 core platform_driver callbacks and their implementation
> and export the implementation, to make it possible to deterministically
> instantiate the dwc3 core as part of the dwc3 glue drivers and to
> allow flattening of the DeviceTree representation.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
> ---
>  drivers/usb/dwc3/core.c | 149 ++++++++++++++++++++++++++++++------------------
>  drivers/usb/dwc3/glue.h |  22 +++++++
>  2 files changed, 117 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index c22b8678e02e..930d812a9fbb 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -36,6 +36,7 @@
>
>  #include "core.h"
>  #include "gadget.h"
> +#include "glue.h"
>  #include "io.h"
>
>  #include "debug.h"
> @@ -2129,27 +2130,14 @@ static int dwc3_get_num_ports(struct dwc3 *dwc)
>  	return 0;
>  }
>
> -static int dwc3_probe(struct platform_device *pdev)
> +int dwc3_init(struct dwc3 *dwc, struct resource *res)

Maybe need data struct, which included res. It may need pass down more
information in future.

>  {
> -	struct device		*dev = &pdev->dev;
> -	struct resource		*res, dwc_res;
> +	struct device		*dev = dwc->dev;
> +	struct resource		dwc_res;
>  	unsigned int		hw_mode;
>  	void __iomem		*regs;
> -	struct dwc3		*dwc;
>  	int			ret;
>
...

> +++ b/drivers/usb/dwc3/glue.h
> @@ -0,0 +1,22 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * glue.h - DesignWare USB3 DRD glue header
> + */
> +
> +#ifndef __DRIVERS_USB_DWC3_GLUE_H
> +#define __DRIVERS_USB_DWC3_GLUE_H
> +
> +#include <linux/types.h>
> +#include "core.h"
> +
> +int dwc3_init(struct dwc3 *dwc, struct resource *res);
> +void dwc3_uninit(struct dwc3 *dwc);
> +
> +int dwc3_runtime_suspend(struct dwc3 *dwc);
> +int dwc3_runtime_resume(struct dwc3 *dwc);
> +int dwc3_runtime_idle(struct dwc3 *dwc);
> +int dwc3_suspend(struct dwc3 *dwc);
> +int dwc3_resume(struct dwc3 *dwc);
> +void dwc3_complete(struct dwc3 *dwc);

dwc3_usb_*()? There may be name polution in future. There are many IPs
created by dwc.

Frank

> +
> +#endif
>
> --
> 2.45.2
>