Re: [RFC PATCH] USB: misc: Add usb_hub_pwr driver

Peter Chen
2020-09-02T05:31:17Z

On 20-09-01 13:21:43, Matthias Kaehlcke wrote:
> The driver combo usb_hub_pwr/usb_hub_psupply allows to control
> the power supply of an onboard USB hub.
>
> The drivers address two issues:
> - a USB hub needs to be powered before it can be discovered
> - battery powered devices may want to switch the USB hub off
> during suspend to extend battery life
>
> The regulator of the hub is controlled by the usb_hub_psupply
> platform driver. The regulator is switched on when the platform
> device is initialized, which enables discovery of the hub. The
> driver provides an external interface to enable/disable the
> power supply which is used by the usb_hub_pwr driver.
>
> The usb_hub_pwr extends the generic USB hub driver. The device is
> initialized when the hub is discovered by the USB subsystem. It
> uses the usb_hub_psupply interface to make its own request to
> enable the regulator (increasing the use count to 2).
>
> During system suspend usb_hub_pwr checks if any wakeup capable
> devices are connected to the hub. If not it 'disables' the hub
> regulator (decreasing the use count to 1, hence the regulator
> stays enabled for now). When the usb_hub_psupply device suspends
> it disables the hub regulator unconditionally (decreasing the use
> count to 0 or 1, depending on the actions of usb_hub_pwr). This
> is done to allow the usb_hub_pwr device to control the state of
> the regulator during system suspend.
>
> Upon resume usb_hub_psupply enables the regulator again, the
> usb_hub_pwr device does the same if it disabled the regulator
> during resume.

Hi Matthias,

I did similar several years ago [1], but the concept (power sequence)
doesn't be accepted by power maintainer. Your patch introduce an new
way to fix this long-term issue, I have an idea to fix it more generally.

- Create a table (say usb_pm_table) for USB device which needs to do
initial power on and power management during suspend suspend/resume based
on VID and PID, example: usb/core/quirks.c
- After hub (both roothub and intermediate hub) device is created, search
the DT node under this hub, and see if the device is in usb_pm_table. If
it is in it, create a platform device, say usb-power-supply, and the
related driver is like your usb_hub_psupply.c, the parent of this device
is controller device.
- After this usb-power-supply device is probed, do initial power on at
probe, eg, clock, regulator, reset-gpio.
- This usb-power-supply device system suspend operation should be called after
onboard device has suspended since it is created before it. No runtime PM ops
are needed for it.
- When the hub is removed, delete this platform device.

What's your opinion?

[1] https://lore.kernel.org/lkml/1498027328-25078-1-git-send-email-peter.chen@nxp.com/

Peter
>
> Co-developed-by: Ravi Chandra Sadineni <ravisadineni@chromium.org>
> Signed-off-by: Ravi Chandra Sadineni <ravisadineni@chromium.org>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> The driver currently only supports a single power supply. This should
> work for most/many configurations/hubs, support for multiple power
> supplies can be added later if needed.
>
> No DT bindings are included since this is just a RFC. Here is a DT
> example:
>
> usb_hub_psupply: usb-hub-psupply {
> compatible = "linux,usb_hub_psupply";
> vdd-supply = <&pp3300_hub>;
> };
>
> &usb_1_dwc3 {
> /* 2.0 hub on port 1 */
> hub@1 {
> compatible = "usbbda,5411";
> reg = <1>;
> psupply = <&usb_hub_psupply>;
> };
>
> /* 3.0 hub on port 2 */
> hub@2 {
> compatible = "usbbda,411";
> reg = <2>;
> psupply = <&usb_hub_psupply>;
> };
> };
>
> drivers/usb/misc/Kconfig | 14 +++
> drivers/usb/misc/Makefile | 1 +
> drivers/usb/misc/usb_hub_psupply.c | 112 ++++++++++++++++++
> drivers/usb/misc/usb_hub_psupply.h | 9 ++
> drivers/usb/misc/usb_hub_pwr.c | 177 +++++++++++++++++++++++++++++
> 5 files changed, 313 insertions(+)
> create mode 100644 drivers/usb/misc/usb_hub_psupply.c
> create mode 100644 drivers/usb/misc/usb_hub_psupply.h
> create mode 100644 drivers/usb/misc/usb_hub_pwr.c
>
> diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
> index 6818ea689cd9..79ed50e6a7bf 100644
> --- a/drivers/usb/misc/Kconfig
> +++ b/drivers/usb/misc/Kconfig
> @@ -275,3 +275,17 @@ config USB_CHAOSKEY
>
> To compile this driver as a module, choose M here: the
> module will be called chaoskey.
> +
> +config USB_HUB_PWR
> + tristate "Control power supply for onboard USB hubs"
> + depends on PM
> + help
> + Say Y here if you want to control the power supply of an
> + onboard USB hub. The driver switches the power supply of the
> + hub on, to make sure the hub can be discovered. During system
> + suspend the power supply is switched off, unless a wakeup
> + capable device is connected to the hub. This may reduce power
> + consumption on battery powered devices.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called usb_hub_pwr.
> diff --git a/drivers/usb/misc/Makefile b/drivers/usb/misc/Makefile
> index da39bddb0604..2bd02388ca62 100644
> --- a/drivers/usb/misc/Makefile
> +++ b/drivers/usb/misc/Makefile
> @@ -31,3 +31,4 @@ obj-$(CONFIG_USB_CHAOSKEY) += chaoskey.o
>
> obj-$(CONFIG_USB_SISUSBVGA) += sisusbvga/
> obj-$(CONFIG_USB_LINK_LAYER_TEST) += lvstest.o
> +obj-$(CONFIG_USB_HUB_PWR) += usb_hub_pwr.o usb_hub_psupply.o
> diff --git a/drivers/usb/misc/usb_hub_psupply.c b/drivers/usb/misc/usb_hub_psupply.c
> new file mode 100644
> index 000000000000..6a155ae1f831
> --- /dev/null
> +++ b/drivers/usb/misc/usb_hub_psupply.c
> @@ -0,0 +1,112 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2020, Google LLC
> + */
> +
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +
> +struct usb_hub_psupply_dev {
> + struct regulator *vdd;
> +};
> +
> +int usb_hub_psupply_on(struct device *dev)
> +{
> + struct usb_hub_psupply_dev *usb_hub_psupply = dev_get_drvdata(dev);
> + int err;
> +
> + err = regulator_enable(usb_hub_psupply->vdd);
> + if (err) {
> + dev_err(dev, "failed to enable regulator: %d\n", err);
> + return err;
> + }
> +
> + return 0;
> +
> +}
> +EXPORT_SYMBOL_GPL(usb_hub_psupply_on);
> +
> +int usb_hub_psupply_off(struct device *dev)
> +{
> + struct usb_hub_psupply_dev *usb_hub_psupply = dev_get_drvdata(dev);
> + int err;
> +
> + err = regulator_disable(usb_hub_psupply->vdd);
> + if (err) {
> + dev_err(dev, "failed to enable regulator: %d\n", err);
> + return err;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_hub_psupply_off);
> +
> +static int usb_hub_psupply_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct usb_hub_psupply_dev *usb_hub_psupply;
> +
> + usb_hub_psupply = devm_kzalloc(dev, sizeof(*usb_hub_psupply), GFP_KERNEL);
> + if (!usb_hub_psupply)
> + return -ENOMEM;
> +
> + dev_set_drvdata(dev, usb_hub_psupply);
> +
> + usb_hub_psupply->vdd = devm_regulator_get(dev, "vdd");
> + if (IS_ERR(usb_hub_psupply->vdd))
> + return PTR_ERR(usb_hub_psupply->vdd);
> +
> + return usb_hub_psupply_on(dev);
> +}
> +
> +static int usb_hub_psupply_remove(struct platform_device *pdev)
> +{
> + return usb_hub_psupply_off(&pdev->dev);
> +}
> +
> +static int usb_hub_psupply_suspend(struct platform_device *pdev, pm_message_t msg)
> +{
> + return usb_hub_psupply_off(&pdev->dev);
> +}
> +
> +static int usb_hub_psupply_resume(struct platform_device *pdev)
> +{
> + return usb_hub_psupply_on(&pdev->dev);
> +}
> +
> +static const struct of_device_id usb_hub_psupply_match[] = {
> + { .compatible = "linux,usb_hub_psupply" },
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, usb_hub_psupply_match);
> +
> +static struct platform_driver usb_hub_psupply_driver = {
> + .probe = usb_hub_psupply_probe,
> + .remove = usb_hub_psupply_remove,
> + .suspend = usb_hub_psupply_suspend,
> + .resume = usb_hub_psupply_resume,
> + .driver = {
> + .name = "usb-hub-psupply",
> + .of_match_table = usb_hub_psupply_match,
> + },
> +};
> +
> +static int __init usb_hub_psupply_init(void)
> +{
> + return platform_driver_register(&usb_hub_psupply_driver);
> +}
> +device_initcall(usb_hub_psupply_init);
> +
> +static void __exit usb_hub_psupply_exit(void)
> +{
> + platform_driver_unregister(&usb_hub_psupply_driver);
> +}
> +module_exit(usb_hub_psupply_exit);
> +
> +MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
> +MODULE_DESCRIPTION("USB Hub Power Supply");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/usb/misc/usb_hub_psupply.h b/drivers/usb/misc/usb_hub_psupply.h
> new file mode 100644
> index 000000000000..284e88f45fcf
> --- /dev/null
> +++ b/drivers/usb/misc/usb_hub_psupply.h
> @@ -0,0 +1,9 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#ifndef _USB_HUB_PSUPPLY_H
> +#define _USB_HUB_PSUPPLY_H
> +
> +int usb_hub_psupply_on(struct device *dev);
> +int usb_hub_psupply_off(struct device *dev);
> +
> +#endif /* _USB_HUB_PSUPPLY_H */
> diff --git a/drivers/usb/misc/usb_hub_pwr.c b/drivers/usb/misc/usb_hub_pwr.c
> new file mode 100644
> index 000000000000..33945ca4a8c0
> --- /dev/null
> +++ b/drivers/usb/misc/usb_hub_pwr.c
> @@ -0,0 +1,177 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * USB hub power control
> + *
> + * Copyright (c) 2020, Google LLC
> + */
> +
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/power_supply.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +#include <linux/usb/hcd.h>
> +#include "../core/usb.h"
> +#include "usb_hub_psupply.h"
> +
> +#define VENDOR_ID_REALTEK 0x0bda
> +
> +struct usb_hub_pwr_dev {
> + struct regulator *vdd;
> + struct device *psupply_dev;
> + bool powered_off;
> +};
> +
> +static struct device *usb_pwr_find_psupply_dev(struct device *dev)
> +{
> + const phandle *ph;
> + struct device_node *np;
> + struct platform_device *pdev;
> +
> + ph = of_get_property(dev->of_node, "psupply", NULL);
> + if (!ph) {
> + dev_err(dev, "failed to read 'psupply' 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 power supply\n");
> + return ERR_PTR(-EINVAL);
> + }
> +
> + pdev = of_find_device_by_node(np);
> + of_node_put(np);
> + if (!pdev)
> + return ERR_PTR(-EPROBE_DEFER);
> +
> + return &pdev->dev;
> +}
> +
> +static int usb_hub_pwr_probe(struct usb_device *udev)
> +{
> + struct device *dev = &udev->dev;
> + struct usb_hub_pwr_dev *uhpw;
> + struct device *psupply_dev;
> + int err;
> +
> + /* ignore supported hubs without device tree node */
> + if (!dev->of_node)
> + return -ENODEV;
> +
> + psupply_dev = usb_pwr_find_psupply_dev(dev);
> + if (IS_ERR(psupply_dev))
> + return PTR_ERR(psupply_dev);
> +
> + err = usb_generic_driver_probe(udev);
> + if (err) {
> + put_device(psupply_dev);
> + return err;
> + }
> +
> + uhpw = devm_kzalloc(dev, sizeof(*uhpw), GFP_KERNEL);
> + if (!uhpw) {
> + put_device(psupply_dev);
> + return -ENOMEM;
> + }
> +
> + dev_set_drvdata(&udev->dev, uhpw);
> +
> + uhpw->psupply_dev = psupply_dev;
> +
> + err = usb_hub_psupply_on(psupply_dev);
> + if (err) {
> + dev_err(dev, "failed to enable regulator: %d\n", err);
> + put_device(psupply_dev);
> + return err;
> + }
> +
> + return 0;
> +}
> +
> +static void usb_hub_pwr_disconnect(struct usb_device *udev)
> +{
> + struct usb_hub_pwr_dev *uhpw = dev_get_drvdata(&udev->dev);
> +
> + usb_hub_psupply_off(uhpw->psupply_dev);
> + put_device(uhpw->psupply_dev);
> +}
> +
> +static int usb_hub_pwr_suspend(struct usb_device *udev, pm_message_t msg)
> +{
> + struct usb_hub_pwr_dev *uhpw = dev_get_drvdata(&udev->dev);
> + int err;
> +
> + err = usb_generic_driver_suspend(udev, msg);
> + if (err)
> + return err;
> +
> + if (!usb_wakeup_enabled_descendants(udev)) {
> + usb_port_disable(udev);
> +
> + err = usb_hub_psupply_off(uhpw->psupply_dev);
> + if (err)
> + return err;
> +
> + uhpw->powered_off = true;
> + }
> +
> + return 0;
> +}
> +
> +static int usb_hub_pwr_resume(struct usb_device *udev, pm_message_t msg)
> +{
> + struct usb_hub_pwr_dev *uhpw = dev_get_drvdata(&udev->dev);
> + int err;
> +
> + if (uhpw->powered_off) {
> + err = usb_hub_psupply_on(uhpw->psupply_dev);
> + if (err)
> + return err;
> +
> + uhpw->powered_off = false;
> + }
> +
> + return usb_generic_driver_resume(udev, msg);
> +}
> +
> +static const struct usb_device_id 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, hub_id_table);
> +
> +static struct usb_device_driver usb_hub_pwr_driver = {
> +
> + .name = "usb-hub-pwr",
> + .probe = usb_hub_pwr_probe,
> + .disconnect = usb_hub_pwr_disconnect,
> + .suspend = usb_hub_pwr_suspend,
> + .resume = usb_hub_pwr_resume,
> + .id_table = hub_id_table,
> +};
> +
> +static int __init usb_hub_pwr_driver_init(void)
> +{
> + return usb_register_device_driver(&usb_hub_pwr_driver, THIS_MODULE);
> +}
> +
> +static void __exit usb_hub_pwr_driver_exit(void)
> +{
> + usb_deregister_device_driver(&usb_hub_pwr_driver);
> +}
> +
> +module_init(usb_hub_pwr_driver_init);
> +module_exit(usb_hub_pwr_driver_exit);
> +
> +MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
> +MODULE_DESCRIPTION("USB Hub Power Control");
> +MODULE_LICENSE("GPL v2");
> --
> 2.28.0.402.g5ffc5be6b7-goog
>

--

Thanks,
Peter Chen