Re: [PATCH 2/2] USB: misc: Add onboard_usb_hub driver

Peter Chen
2020-09-15T02:55:17Z

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.
>
> 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.
>
> 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 = &pdev->dev;
> + struct onboard_hub *hub;
> +
> + hub = devm_kzalloc(dev, sizeof(*hub), GFP_KERNEL);
> + if (!hub)
> + return -ENOMEM;
> +
> + hub->vdd = devm_regulator_get(dev, "vdd");
> + if (IS_ERR(hub->vdd))
> + return PTR_ERR(hub->vdd);
> +
> + hub->dev = dev;
> + mutex_init(&hub->lock);
> + INIT_LIST_HEAD(&hub->udev_list);
> +
> + hub->cfg.power_off_in_suspend = of_property_read_bool(dev->of_node, "power-off-in-suspend");
> + hub->cfg.wakeup_source = 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 = dev_get_drvdata(&pdev->dev);
> +
> + return onboard_hub_power_off(hub);
> +}
> +
> +static const struct of_device_id onboard_hub_match[] = {
> + { .compatible = "onboard-usb-hub" },
> + { .compatible = "realtek,rts5411" },
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, onboard_hub_match);
> +
> +static struct platform_driver onboard_hub_driver = {
> + .probe = onboard_hub_probe,
> + .remove = onboard_hub_remove,
> +#ifdef CONFIG_PM
> + .suspend = onboard_hub_suspend,
> + .resume = onboard_hub_resume,
> +#endif
> + .driver = {
> + .name = "onboard-usb-hub",
> + .of_match_table = 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 = of_get_property(dev->of_node, "hub", NULL);
> + if (!ph) {
> + dev_err(dev, "failed to read 'hub' property\n");
> + return ERR_PTR(-EINVAL);
> + }
> +
> + np = 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 = 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 = &udev->dev;
> + struct onboard_hub *hub;
> +
> + /* ignore supported hubs without device tree node */
> + if (!dev->of_node)
> + return -ENODEV;
> +
> + hub = _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 = 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[] = {
> + { .idVendor = VENDOR_ID_REALTEK,
> + .idProduct = 0x0411, /* RTS5411 USB 3.0 */
> + .match_flags = USB_DEVICE_ID_MATCH_DEVICE },
> + { .idVendor = VENDOR_ID_REALTEK,
> + .idProduct = 0x5411, /* RTS5411 USB 2.0 */
> + .match_flags = USB_DEVICE_ID_MATCH_DEVICE },
> + {},
> +};
> +
> +MODULE_DEVICE_TABLE(usb, onboard_hub_id_table);
> +
> +static struct usb_device_driver onboard_hub_usbdev_driver = {
> +
> + .name = "onboard-usb-hub",
> + .probe = onboard_hub_usbdev_probe,
> + .disconnect = onboard_hub_usbdev_disconnect,
> + .generic_subclass = 1,
> + .supports_autosuspend = 1,
> + .id_table = onboard_hub_id_table,
> +};
> +
> +/************************** Driver (de)registration **************************/
> +
> +static int __init onboard_hub_init(void)
> +{
> + int rc;
> +
> + rc = platform_driver_register(&onboard_hub_driver);
> + if (rc)
> + return rc;
> +
> + return usb_register_device_driver(&onboard_hub_usbdev_driver, THIS_MODULE);
> +}
> +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");
> --
> 2.28.0.618.gf4bc123cb7-goog
>

--

Thanks,
Peter Chen