Message-ID: <20190624095827.GA6501@kuha.fi.intel.com>
Date:   Mon, 24 Jun 2019 12:58:27 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        Li Jun <jun.li@....com>,
        Badhri Jagan Sridharan <badhri@...gle.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Min Guo <min.guo@...iatek.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Biju Das <biju.das@...renesas.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Yu Chen <chenyu56@...wei.com>,
        Nagarjuna Kristam <nkristam@...dia.com>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>
Subject: Re: [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@...iatek.com>
> Tested-by: Nagarjuna Kristam <nkristam@...dia.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@...iatek.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@...iatek.com>");
> +MODULE_DESCRIPTION("USB Type-B GPIO connector driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.21.0

thanks,

-- 
heikki

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