Message-id: <54BF3918.2000300@samsung.com>
Date:	Wed, 21 Jan 2015 14:28:56 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Roger Quadros <rogerq@...com>
Cc:	balbi@...com, tony@...mide.com, myungjoo.ham@...sung.com,
	george.cherian@...com, nsekhar@...com, devicetree@...r.kernel.org,
	linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] extcon: gpio-usb: Introduce gpio usb extcon driver

Hi Roger,

On 01/20/2015 02:52 AM, Roger Quadros wrote:
> This driver observes the USB ID pin connected over a GPIO and
> updates the USB cable extcon states accordingly.
> 
> The existing GPIO extcon driver is not suitable for this purpose
> as it needs to be taught to understand USB cable states and it
> can't handle more than one cable per instance.
> 
> For the USB case we need to handle 2 cable states.
> 1) USB (attach/detach)
> 2) USB-Host (attach/detach)
> 
> This driver can be easily updated in the future to handle VBUS
> events in case it happens to be available on GPIO for any platform.
> 
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
>  .../devicetree/bindings/extcon/extcon-usb.txt      |  20 ++
>  drivers/extcon/Kconfig                             |   7 +
>  drivers/extcon/Makefile                            |   1 +
>  drivers/extcon/extcon-gpio-usb.c                   | 225 +++++++++++++++++++++
>  4 files changed, 253 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/extcon/extcon-usb.txt
>  create mode 100644 drivers/extcon/extcon-gpio-usb.c
> 
> diff --git a/Documentation/devicetree/bindings/extcon/extcon-usb.txt b/Documentation/devicetree/bindings/extcon/extcon-usb.txt
> new file mode 100644
> index 0000000..171c5a4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/extcon/extcon-usb.txt

Need to rename from extcon-usb.txt to extcon-gpio-usb.txt.

> @@ -0,0 +1,20 @@
> +USB Extcon device
> +
> +This is a virtual device used to generate USB cable states from the USB ID pin
> +connected to a GPIO pin.
> +
> +Required properties:
> +- compatible: Should be "linux,extcon-usb"

I think you better use "linux,extcon-gpio-usb"
because the point of this driver use the gpio for usb cable.

> +- id-gpio: gpio for USB ID pin. See gpio binding.
> +
> +Example:
> +	extcon_usb1 {
> +		compatible = "linux,extcon-usb";

ditto.

> +		id-gpio = <&gpio6 1 GPIO_ACTIVE_HIGH>;
> +	}
> +
> +	usb@1 {
> +		...
> +		extcon = <&extcon_usb1>;
> +		...
> +	};
> diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
> index 6a1f7de..8106a83 100644
> --- a/drivers/extcon/Kconfig
> +++ b/drivers/extcon/Kconfig
> @@ -35,6 +35,13 @@ config EXTCON_GPIO
>  	  Say Y here to enable GPIO based extcon support. Note that GPIO
>  	  extcon supports single state per extcon instance.
>  
> +config EXTCON_GPIO_USB
> +	tristate "USB GPIO extcon support"
> +	depends on GPIOLIB
> +	help
> +	  Say Y here to enable GPIO based USB cable detection extcon support.
> +	  Used typically if GPIO is used for USB ID pin detection.
> +
>  config EXTCON_MAX14577
>  	tristate "MAX14577/77836 EXTCON Support"
>  	depends on MFD_MAX14577
> diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
> index 0370b42..bae594b 100644
> --- a/drivers/extcon/Makefile
> +++ b/drivers/extcon/Makefile
> @@ -12,3 +12,4 @@ obj-$(CONFIG_EXTCON_MAX8997)	+= extcon-max8997.o
>  obj-$(CONFIG_EXTCON_PALMAS)	+= extcon-palmas.o
>  obj-$(CONFIG_EXTCON_RT8973A)	+= extcon-rt8973a.o
>  obj-$(CONFIG_EXTCON_SM5502)	+= extcon-sm5502.o
> +obj-$(CONFIG_EXTCON_GPIO_USB)	+= extcon-gpio-usb.o

Need to re-order it alphabetically.

> diff --git a/drivers/extcon/extcon-gpio-usb.c b/drivers/extcon/extcon-gpio-usb.c
> new file mode 100644
> index 0000000..aeb2298
> --- /dev/null
> +++ b/drivers/extcon/extcon-gpio-usb.c
> @@ -0,0 +1,225 @@
> +/**
> + * drivers/extcon/extcon_gpio_usb.c - USB GPIO extcon driver
> + *
> + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
> + *

Remove un-necessary blank line.

> + * Author: Roger Quadros <rogerq@...com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/extcon.h>
> +#include <linux/extcon/extcon-gpio.h>

Is it necessary? I think it is your mistake?

> +#include <linux/gpio.h>

Don't need it because 'of_gpio.h' includes already 'gpio.h'.

> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/workqueue.h>
> +
> +#define USB_GPIO_DEBOUNCE_MS	20	/* ms */
> +
> +struct usb_extcon_info {
> +	struct device *dev;
> +	struct extcon_dev *edev;
> +
> +	struct gpio_desc *id_gpiod;
> +	int id_irq;
> +
> +	unsigned long debounce_jiffies;
> +	struct delayed_work wq_detcable;
> +};
> +
> +/* List of detectable cables */
> +enum {
> +	EXTCON_CABLE_USB = 0,
> +	EXTCON_CABLE_USB_HOST,
> +
> +	EXTCON_CABLE_END,
> +};
> +
> +static const char *usb_extcon_cable[] = {
> +	[EXTCON_CABLE_USB] = "USB",
> +	[EXTCON_CABLE_USB_HOST] = "USB-Host",
> +	NULL,
> +};
> +
> +static void usb_extcon_detect_cable(struct work_struct *work)
> +{
> +	int id;
> +	struct usb_extcon_info *info;
> +	const char **cable_names;
> +
> +	info  = container_of(to_delayed_work(work), struct usb_extcon_info,
> +			     wq_detcable);
> +	cable_names = info->edev->supported_cable;

I think you can use 'usb_extcon_cable' instead of 'cable_names'.
So, you will remove 'cable_names' variable.

> +
> +	/* check ID and update cable state */
> +	id = gpiod_get_value_cansleep(info->id_gpiod);
> +
> +	if (id) {
> +		/*
> +		 * ID = 1 means USB HOST cable detached.
> +		 * As we don't have event for USB peripheral cable attached,
> +		 * we simulate USB peripheral attach here.
> +		 */
> +		extcon_set_cable_state(info->edev,
> +				       cable_names[EXTCON_CABLE_USB_HOST],
> +				       false);
> +		extcon_set_cable_state(info->edev,
> +				       cable_names[EXTCON_CABLE_USB], true);
> +	} else {
> +		/*
> +		 * ID = 0 means USB HOST cable attached.
> +		 * As we don't have event for USB peripheral cable detached,
> +		 * we simulate USB peripheral detach here.
> +		 */
> +		extcon_set_cable_state(info->edev,
> +				       cable_names[EXTCON_CABLE_USB], false);
> +		extcon_set_cable_state(info->edev,
> +				       cable_names[EXTCON_CABLE_USB_HOST],
> +				       true);
> +	}
> +}
> +
> +static irqreturn_t usb_irq_handler(int irq, void *dev_id)
> +{
> +	struct usb_extcon_info *info = dev_id;
> +
> +	/* debounce the GPIO via delayed work */

I think this comment is not necessary.

> +	queue_delayed_work(system_power_efficient_wq, &info->wq_detcable,
> +			   info->debounce_jiffies);
> +	return IRQ_HANDLED;
> +}
> +
> +static int usb_extcon_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct usb_extcon_info *info;
> +	int ret;
> +
> +	if (!np)
> +		return -EINVAL;
> +
> +	info = devm_kzalloc(&pdev->dev, sizeof(struct usb_extcon_info),

sizeof(struct usb_extcon_info) -> sizeof(*info)

> +			    GFP_KERNEL);
> +	if (!info)
> +		return -ENOMEM;
> +
> +	info->dev = dev;
> +	info->id_gpiod = devm_gpiod_get(&pdev->dev, "id");
> +	if (IS_ERR(info->id_gpiod)) {
> +		dev_err(dev, "failed to get ID GPIO\n");
> +		return PTR_ERR(info->id_gpiod);
> +	}
> +
> +	ret = gpiod_set_debounce(info->id_gpiod,
> +				 USB_GPIO_DEBOUNCE_MS * 1000);
> +	if (ret < 0)
> +		info->debounce_jiffies = msecs_to_jiffies(USB_GPIO_DEBOUNCE_MS);
> +
> +	INIT_DELAYED_WORK(&info->wq_detcable, usb_extcon_detect_cable);
> +
> +	info->id_irq = gpiod_to_irq(info->id_gpiod);
> +	if (info->id_irq < 0) {
> +		dev_err(dev, "failed to get ID IRQ\n");
> +		return info->id_irq;
> +	}
> +
> +	ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
> +					usb_irq_handler,
> +					IRQF_SHARED | IRQF_ONESHOT,

I prefer to add IRQF_NO_SUSPEND flag because IRQF_NO_SUSPEND flag is necessary
for wake-up from freeze pm state.

> +					pdev->name, info);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to request handler for ID IRQ\n");
> +		return ret;
> +	}
> +
> +	info->edev = devm_extcon_dev_allocate(dev, usb_extcon_cable);
> +	if (IS_ERR(info->edev)) {
> +		dev_err(dev, "failed to allocate extcon device\n");
> +		return -ENOMEM;
> +	}
> +
> +	ret = devm_extcon_dev_register(dev, info->edev);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to allocate extcon device\n");

Wrong error information, you have to change verb (allocate -> register)

> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, info);

Need blank line.

> +	/* Perform initial detection */
> +	usb_extcon_detect_cable(&info->wq_detcable.work);
> +
> +	return 0;
> +}
> +
> +static int usb_extcon_remove(struct platform_device *pdev)
> +{
> +	struct usb_extcon_info *info = platform_get_drvdata(pdev);
> +
> +	cancel_delayed_work_sync(&info->wq_detcable);
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int usb_extcon_suspend(struct device *dev)
> +{
> +	struct usb_extcon_info *info;
> +
> +	info = dev_get_drvdata(dev);

Simplify this code as following:
	struct usb_extcon_info *info = dev_get_drvdata(dev);

> +
> +	if (!IS_ERR(info->id_gpiod))

I think that it is sufficient cheking without IS_ERR macro as following:
	if (info->id_gpiod)

> +		enable_irq_wake(info->id_irq);
> +
> +	return 0;
> +}
> +
> +static int usb_extcon_resume(struct device *dev)
> +{
> +	struct usb_extcon_info *info;
> +
> +	info = dev_get_drvdata(dev);

ditto.

> +
> +	if (!IS_ERR(info->id_gpiod))

ditto.

> +		disable_irq_wake(info->id_irq);
> +
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(usb_extcon_pm_ops,
> +			 usb_extcon_suspend, usb_extcon_resume);
> +
> +static struct of_device_id usb_extcon_dt_match[] = {
> +	{ .compatible = "linux,extcon-usb", },

Change compatible name from "linux,extcon-usb", to "linux,extcon-gpio-usb".

> +	{ /* end */ }
> +};
> +
> +static struct platform_driver usb_extcon_driver = {
> +	.probe		= usb_extcon_probe,
> +	.remove		= usb_extcon_remove,
> +	.driver		= {
> +		.name	= "extcon-usb",
> +		.pm	= &usb_extcon_pm_ops,
> +		.of_match_table = usb_extcon_dt_match,
> +	},
> +};
> +
> +module_platform_driver(usb_extcon_driver);
> +
> +MODULE_AUTHOR("Roger Quadros <rogerq@...com>");
> +MODULE_DESCRIPTION("USB GPIO extcon driver");
> +MODULE_LICENSE("GPL v2");
> 

Thanks,
Chanwoo Cho

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