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From:   Peter Chen <peter.chen@nxp.com>
To:     Matthias Kaehlcke <mka@chromium.org>
CC:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Bastien Nocera <hadess@hadess.net>,
        Ravi Chandra Sadineni <ravisadineni@chromium.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        Stephen Boyd <swboyd@chromium.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Douglas Anderson <dianders@chromium.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Alexander A. Klimov" <grandmaster@al2klimov.de>,
        Masahiro Yamada <masahiroy@kernel.org>
Subject: Re: [PATCH 2/2] USB: misc: Add onboard_usb_hub driver
Thread-Topic: [PATCH 2/2] USB: misc: Add onboard_usb_hub driver
Thread-Index: AQHWisa8s1Sayn6UyUeJIx1ZNmduw6lpAX4A
Date:   Tue, 15 Sep 2020 02:55:06 +0000
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On 20-09-14 11:27:49, Matthias Kaehlcke wrote:
> The main issue this driver addresses is that a USB hub needs to be
> powered before it can be discovered. For onboard hubs this is often
> solved by supplying the hub with an 'always-on' regulator, which is
> kind of a hack. Some onboard hubs may require further initialization
> steps, like changing the state of a GPIO or enabling a clock, which
> requires further hacks. This driver creates a platform device
> representing the hub which performs the necessary initialization.
> Currently it only supports switching on a single regulator, support
> for multiple regulators or other actions can be added as needed.
> Different initialization sequences can be supported based on the
> compatible string.
>=20
> Besides performing the initialization the driver can be configured
> to power the hub off during system suspend. This can help to extend
> battery life on battery powered devices, which have no requirements
> to keep the hub powered during suspend. The driver can also be
> configured to leave the hub powered when a wakeup capable USB device
> is connected when suspending, and keeping it powered otherwise.
>=20
> Technically the driver consists of two drivers, the platform driver
> described above and a very thin USB driver that subclasses the
> generic hub driver. The purpose of this driver is to provide the
> platform driver with the USB devices corresponding to the hub(s)
> (a hub controller may provide multiple 'logical' hubs, e.g. one
> to support USB 2.0 and another for USB 3.x).

I agree with Alan, you may change this driver to apply for generic
onboard USB devices.

> +static int onboard_hub_probe(struct platform_device *pdev)
> +{
> +	struct device *dev =3D &pdev->dev;
> +	struct onboard_hub *hub;
> +
> +	hub =3D devm_kzalloc(dev, sizeof(*hub), GFP_KERNEL);
> +	if (!hub)
> +		return -ENOMEM;
> +
> +	hub->vdd =3D devm_regulator_get(dev, "vdd");
> +	if (IS_ERR(hub->vdd))
> +		return PTR_ERR(hub->vdd);
> +
> +	hub->dev =3D dev;
> +	mutex_init(&hub->lock);
> +	INIT_LIST_HEAD(&hub->udev_list);
> +
> +	hub->cfg.power_off_in_suspend =3D of_property_read_bool(dev->of_node, "=
power-off-in-suspend");
> +	hub->cfg.wakeup_source =3D of_property_read_bool(dev->of_node, "wakeup-=
source");

Do you really need these two properties? If the device (and its children
if existed) has wakeup enabled, you keep power in suspend, otherwise,
you could close it, any exceptions?

Peter


> +
> +	dev_set_drvdata(dev, hub);
> +
> +	return onboard_hub_power_on(hub);
> +}
> +
> +static int onboard_hub_remove(struct platform_device *pdev)
> +{
> +	struct onboard_hub *hub =3D dev_get_drvdata(&pdev->dev);
> +
> +	return onboard_hub_power_off(hub);
> +}
> +
> +static const struct of_device_id onboard_hub_match[] =3D {
> +	{ .compatible =3D "onboard-usb-hub" },
> +	{ .compatible =3D "realtek,rts5411" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, onboard_hub_match);
> +
> +static struct platform_driver onboard_hub_driver =3D {
> +	.probe =3D onboard_hub_probe,
> +	.remove =3D onboard_hub_remove,
> +#ifdef CONFIG_PM
> +	.suspend =3D onboard_hub_suspend,
> +	.resume =3D onboard_hub_resume,
> +#endif
> +	.driver =3D {
> +		.name =3D "onboard-usb-hub",
> +		.of_match_table =3D onboard_hub_match,
> +	},
> +};
> +
> +/************************** USB driver **************************/
> +
> +#define VENDOR_ID_REALTEK	0x0bda
> +
> +static struct onboard_hub *_find_onboard_hub(struct device *dev)
> +{
> +	const phandle *ph;
> +	struct device_node *np;
> +	struct platform_device *pdev;
> +
> +	ph =3D of_get_property(dev->of_node, "hub", NULL);
> +	if (!ph) {
> +		dev_err(dev, "failed to read 'hub' property\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	np =3D of_find_node_by_phandle(be32_to_cpu(*ph));
> +	if (!np) {
> +		dev_err(dev, "failed find device node for onboard hub\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	pdev =3D of_find_device_by_node(np);
> +	of_node_put(np);
> +	if (!pdev)
> +		return ERR_PTR(-EPROBE_DEFER);
> +
> +	return dev_get_drvdata(&pdev->dev);
> +}
> +
> +static int onboard_hub_usbdev_probe(struct usb_device *udev)
> +{
> +	struct device *dev =3D &udev->dev;
> +	struct onboard_hub *hub;
> +
> +	/* ignore supported hubs without device tree node */
> +	if (!dev->of_node)
> +		return -ENODEV;
> +
> +	hub =3D _find_onboard_hub(dev);
> +	if (IS_ERR(hub))
> +		return PTR_ERR(dev);
> +
> +	dev_set_drvdata(dev, hub);
> +
> +	onboard_hub_add_usbdev(hub, udev);
> +
> +	return 0;
> +}
> +
> +static void onboard_hub_usbdev_disconnect(struct usb_device *udev)
> +{
> +	struct onboard_hub *hub =3D dev_get_drvdata(&udev->dev);
> +
> +	onboard_hub_remove_usbdev(hub, udev);
> +
> +	put_device(hub->dev);
> +}
> +
> +static const struct usb_device_id onboard_hub_id_table[] =3D {
> +	{ .idVendor =3D VENDOR_ID_REALTEK,
> +	  .idProduct =3D 0x0411, /* RTS5411 USB 3.0 */
> +	  .match_flags =3D USB_DEVICE_ID_MATCH_DEVICE },
> +	{ .idVendor =3D VENDOR_ID_REALTEK,
> +	  .idProduct =3D 0x5411, /* RTS5411 USB 2.0 */
> +	  .match_flags =3D USB_DEVICE_ID_MATCH_DEVICE },
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(usb, onboard_hub_id_table);
> +
> +static struct usb_device_driver onboard_hub_usbdev_driver =3D {
> +
> +	.name =3D "onboard-usb-hub",
> +	.probe =3D onboard_hub_usbdev_probe,
> +	.disconnect =3D onboard_hub_usbdev_disconnect,
> +	.generic_subclass =3D 1,
> +	.supports_autosuspend =3D	1,
> +	.id_table =3D onboard_hub_id_table,
> +};
> +
> +/************************** Driver (de)registration ********************=
******/
> +
> +static int __init onboard_hub_init(void)
> +{
> +	int rc;
> +
> +	rc =3D platform_driver_register(&onboard_hub_driver);
> +	if (rc)
> +		return rc;
> +
> +	return usb_register_device_driver(&onboard_hub_usbdev_driver, THIS_MODU=
LE);
> +}
> +device_initcall(onboard_hub_init);
> +
> +static void __exit onboard_hub_exit(void)
> +{
> +	usb_deregister_device_driver(&onboard_hub_usbdev_driver);
> +	platform_driver_unregister(&onboard_hub_driver);
> +}
> +module_exit(onboard_hub_exit);
> +
> +MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
> +MODULE_DESCRIPTION("Onboard USB Hub driver");
> +MODULE_LICENSE("GPL v2");
> --=20
> 2.28.0.618.gf4bc123cb7-goog
>=20

--=20

Thanks,
Peter Chen=