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SubjectRe: [PATCH v7 09/10] usb: roles: add USB Type-B GPIO connector driver
Hi Chunfeng,

On Tue, Jun 11, 2019 at 04:44:39PM +0800, Chunfeng Yun wrote:
> Due to the requirement of usb-connector.txt binding, the old way
> using extcon to support USB Dual-Role switch is now deprecated
> when use Type-B connector.
> This patch introduces a driver of Type-B connector which typically
> uses an input GPIO to detect USB ID pin, and try to replace the
> function provided by extcon-usb-gpio driver

I'm sorry for asking this so late, but why is this driver a Type-B
specific driver (I really thought somebody had already asked this
question)?

I don't see anything Type-B specific in the driver. Basically it looks
to me like just a gpio based connection detection driver that would
work fine with for example uAB connectors..

> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> Tested-by: Nagarjuna Kristam <nkristam@nvidia.com>
> ---
> v7 changes:
> 1. remove macro DEV_PMS_OPS suggested by Andy
> 2. add tested-by Nagarjuna
>
> v6 changes:
> 1. get usb-role-swtich by usb_role_switch_get()
>
> v5 changes:
> 1. put usb_role_switch when error happens suggested by Biju
> 2. don't treat bype-B connector as a virtual device suggested by Rob
>
> v4 changes:
> 1. remove linux/gpio.h suggested by Linus
> 2. put node when error happens
>
> v3 changes:
> 1. treat bype-B connector as a virtual device;
> 2. change file name again
>
> v2 changes:
> 1. file name is changed
> 2. use new compatible
> ---
> drivers/usb/roles/Kconfig | 11 ++
> drivers/usb/roles/Makefile | 1 +
> drivers/usb/roles/typeb-conn-gpio.c | 284 ++++++++++++++++++++++++++++

..It also drives me crazy that you've put this driver under this
folder. It does not create a role switch so ideally it should not go
under driver/usb/roles/. I think a better place for it would be
drivers/usb/misc/, or actually, maybe it should go under
drivers/usb/common/?

Could you still rename the driver to something like "usb-gpio.c" or
conn-gpio.c, or something else, and also move it under
drivers/usb/misc/ or drivers/usb/common/?

> 3 files changed, 296 insertions(+)
> create mode 100644 drivers/usb/roles/typeb-conn-gpio.c
>
> diff --git a/drivers/usb/roles/Kconfig b/drivers/usb/roles/Kconfig
> index f8b31aa67526..d1156e18a81a 100644
> --- a/drivers/usb/roles/Kconfig
> +++ b/drivers/usb/roles/Kconfig
> @@ -26,4 +26,15 @@ config USB_ROLES_INTEL_XHCI
> To compile the driver as a module, choose M here: the module will
> be called intel-xhci-usb-role-switch.
>
> +config TYPEB_CONN_GPIO
> + tristate "USB Type-B GPIO Connector"

USB GPIO connection detection driver?

> + depends on GPIOLIB
> + help
> + The driver supports USB role switch between host and device via GPIO
> + based USB cable detection, used typically if an input GPIO is used
> + to detect USB ID pin.
> +
> + To compile the driver as a module, choose M here: the module will
> + be called typeb-conn-gpio.ko
> +
> endif # USB_ROLE_SWITCH
> diff --git a/drivers/usb/roles/Makefile b/drivers/usb/roles/Makefile
> index 757a7d2797eb..5d5620d9d113 100644
> --- a/drivers/usb/roles/Makefile
> +++ b/drivers/usb/roles/Makefile
> @@ -3,3 +3,4 @@
> obj-$(CONFIG_USB_ROLE_SWITCH) += roles.o
> roles-y := class.o
> obj-$(CONFIG_USB_ROLES_INTEL_XHCI) += intel-xhci-usb-role-switch.o
> +obj-$(CONFIG_TYPEB_CONN_GPIO) += typeb-conn-gpio.o
> diff --git a/drivers/usb/roles/typeb-conn-gpio.c b/drivers/usb/roles/typeb-conn-gpio.c
> new file mode 100644
> index 000000000000..e3fba1656069
> --- /dev/null
> +++ b/drivers/usb/roles/typeb-conn-gpio.c
> @@ -0,0 +1,284 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * USB Type-B GPIO Connector Driver
> + *
> + * Copyright (C) 2019 MediaTek Inc.
> + *
> + * Author: Chunfeng Yun <chunfeng.yun@mediatek.com>
> + *
> + * Some code borrowed from drivers/extcon/extcon-usb-gpio.c
> + */
> +
> +#include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/usb/role.h>
> +
> +#define USB_GPIO_DEB_MS 20 /* ms */
> +#define USB_GPIO_DEB_US ((USB_GPIO_DEB_MS) * 1000) /* us */
> +
> +#define USB_CONN_IRQF \
> + (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT)
> +
> +struct usb_conn_info {
> + struct device *dev;
> + struct usb_role_switch *role_sw;
> + enum usb_role last_role;
> + struct regulator *vbus;
> + struct delayed_work dw_det;
> + unsigned long debounce_jiffies;
> +
> + struct gpio_desc *id_gpiod;
> + struct gpio_desc *vbus_gpiod;
> + int id_irq;
> + int vbus_irq;
> +};
> +
> +/**
> + * "DEVICE" = VBUS and "HOST" = !ID, so we have:
> + * Both "DEVICE" and "HOST" can't be set as active at the same time
> + * so if "HOST" is active (i.e. ID is 0) we keep "DEVICE" inactive
> + * even if VBUS is on.
> + *
> + * Role | ID | VBUS
> + * ------------------------------------
> + * [1] DEVICE | H | H
> + * [2] NONE | H | L
> + * [3] HOST | L | H
> + * [4] HOST | L | L
> + *
> + * In case we have only one of these signals:
> + * - VBUS only - we want to distinguish between [1] and [2], so ID is always 1
> + * - ID only - we want to distinguish between [1] and [4], so VBUS = ID
> + */
> +static void usb_conn_detect_cable(struct work_struct *work)
> +{
> + struct usb_conn_info *info;
> + enum usb_role role;
> + int id, vbus, ret;
> +
> + info = container_of(to_delayed_work(work),
> + struct usb_conn_info, dw_det);
> +
> + /* check ID and VBUS */
> + id = info->id_gpiod ?
> + gpiod_get_value_cansleep(info->id_gpiod) : 1;
> + vbus = info->vbus_gpiod ?
> + gpiod_get_value_cansleep(info->vbus_gpiod) : id;
> +
> + if (!id)
> + role = USB_ROLE_HOST;
> + else if (vbus)
> + role = USB_ROLE_DEVICE;
> + else
> + role = USB_ROLE_NONE;
> +
> + dev_dbg(info->dev, "role %d/%d, gpios: id %d, vbus %d\n",
> + info->last_role, role, id, vbus);
> +
> + if (info->last_role == role) {
> + dev_warn(info->dev, "repeated role: %d\n", role);
> + return;
> + }
> +
> + if (info->last_role == USB_ROLE_HOST)
> + regulator_disable(info->vbus);
> +
> + ret = usb_role_switch_set_role(info->role_sw, role);
> + if (ret)
> + dev_err(info->dev, "failed to set role: %d\n", ret);
> +
> + if (role == USB_ROLE_HOST) {
> + ret = regulator_enable(info->vbus);
> + if (ret)
> + dev_err(info->dev, "enable vbus regulator failed\n");
> + }
> +
> + info->last_role = role;
> +
> + dev_dbg(info->dev, "vbus regulator is %s\n",
> + regulator_is_enabled(info->vbus) ? "enabled" : "disabled");
> +}
> +
> +static void usb_conn_queue_dwork(struct usb_conn_info *info,
> + unsigned long delay)
> +{
> + queue_delayed_work(system_power_efficient_wq, &info->dw_det, delay);
> +}
> +
> +static irqreturn_t usb_conn_isr(int irq, void *dev_id)
> +{
> + struct usb_conn_info *info = dev_id;
> +
> + usb_conn_queue_dwork(info, info->debounce_jiffies);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int usb_conn_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct usb_conn_info *info;
> + int ret = 0;
> +
> + info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
> + if (!info)
> + return -ENOMEM;
> +
> + info->dev = dev;
> + info->id_gpiod = devm_gpiod_get_optional(dev, "id", GPIOD_IN);
> + if (IS_ERR(info->id_gpiod))
> + return PTR_ERR(info->id_gpiod);
> +
> + info->vbus_gpiod = devm_gpiod_get_optional(dev, "vbus", GPIOD_IN);
> + if (IS_ERR(info->vbus_gpiod))
> + return PTR_ERR(info->vbus_gpiod);
> +
> + if (!info->id_gpiod && !info->vbus_gpiod) {
> + dev_err(dev, "failed to get gpios\n");
> + return -ENODEV;
> + }
> +
> + if (info->id_gpiod)
> + ret = gpiod_set_debounce(info->id_gpiod, USB_GPIO_DEB_US);
> + if (!ret && info->vbus_gpiod)
> + ret = gpiod_set_debounce(info->vbus_gpiod, USB_GPIO_DEB_US);
> + if (ret < 0)
> + info->debounce_jiffies = msecs_to_jiffies(USB_GPIO_DEB_MS);
> +
> + INIT_DELAYED_WORK(&info->dw_det, usb_conn_detect_cable);
> +
> + info->vbus = devm_regulator_get(dev, "vbus");
> + if (IS_ERR(info->vbus)) {
> + dev_err(dev, "failed to get vbus\n");
> + return PTR_ERR(info->vbus);
> + }
> +
> + info->role_sw = usb_role_switch_get(dev);
> + if (IS_ERR(info->role_sw)) {
> + if (PTR_ERR(info->role_sw) != -EPROBE_DEFER)
> + dev_err(dev, "failed to get role switch\n");
> +
> + return PTR_ERR(info->role_sw);
> + }
> +
> + if (info->id_gpiod) {
> + info->id_irq = gpiod_to_irq(info->id_gpiod);
> + if (info->id_irq < 0) {
> + dev_err(dev, "failed to get ID IRQ\n");
> + ret = info->id_irq;
> + goto put_role_sw;
> + }
> +
> + ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
> + usb_conn_isr, USB_CONN_IRQF,
> + pdev->name, info);
> + if (ret < 0) {
> + dev_err(dev, "failed to request ID IRQ\n");
> + goto put_role_sw;
> + }
> + }
> +
> + if (info->vbus_gpiod) {
> + info->vbus_irq = gpiod_to_irq(info->vbus_gpiod);
> + if (info->vbus_irq < 0) {
> + dev_err(dev, "failed to get VBUS IRQ\n");
> + ret = info->vbus_irq;
> + goto put_role_sw;
> + }
> +
> + ret = devm_request_threaded_irq(dev, info->vbus_irq, NULL,
> + usb_conn_isr, USB_CONN_IRQF,
> + pdev->name, info);
> + if (ret < 0) {
> + dev_err(dev, "failed to request VBUS IRQ\n");
> + goto put_role_sw;
> + }
> + }
> +
> + platform_set_drvdata(pdev, info);
> +
> + /* Perform initial detection */
> + usb_conn_queue_dwork(info, 0);
> +
> + return 0;
> +
> +put_role_sw:
> + usb_role_switch_put(info->role_sw);
> + return ret;
> +}
> +
> +static int usb_conn_remove(struct platform_device *pdev)
> +{
> + struct usb_conn_info *info = platform_get_drvdata(pdev);
> +
> + cancel_delayed_work_sync(&info->dw_det);
> +
> + if (info->last_role == USB_ROLE_HOST)
> + regulator_disable(info->vbus);
> +
> + usb_role_switch_put(info->role_sw);
> +
> + return 0;
> +}
> +
> +static int __maybe_unused usb_conn_suspend(struct device *dev)
> +{
> + struct usb_conn_info *info = dev_get_drvdata(dev);
> +
> + if (info->id_gpiod)
> + disable_irq(info->id_irq);
> + if (info->vbus_gpiod)
> + disable_irq(info->vbus_irq);
> +
> + pinctrl_pm_select_sleep_state(dev);
> +
> + return 0;
> +}
> +
> +static int __maybe_unused usb_conn_resume(struct device *dev)
> +{
> + struct usb_conn_info *info = dev_get_drvdata(dev);
> +
> + pinctrl_pm_select_default_state(dev);
> +
> + if (info->id_gpiod)
> + enable_irq(info->id_irq);
> + if (info->vbus_gpiod)
> + enable_irq(info->vbus_irq);
> +
> + usb_conn_queue_dwork(info, 0);
> +
> + return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(usb_conn_pm_ops,
> + usb_conn_suspend, usb_conn_resume);
> +
> +static const struct of_device_id usb_conn_dt_match[] = {
> + { .compatible = "linux,typeb-conn-gpio", },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, usb_conn_dt_match);
> +
> +static struct platform_driver usb_conn_driver = {
> + .probe = usb_conn_probe,
> + .remove = usb_conn_remove,
> + .driver = {
> + .name = "typeb-conn-gpio",
> + .pm = &usb_conn_pm_ops,
> + .of_match_table = usb_conn_dt_match,
> + },
> +};
> +
> +module_platform_driver(usb_conn_driver);
> +
> +MODULE_AUTHOR("Chunfeng Yun <chunfeng.yun@mediatek.com>");
> +MODULE_DESCRIPTION("USB Type-B GPIO connector driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.21.0

thanks,

--
heikki

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