Re: [PATCH v3 1/7] extcon: usb-gpio: Introduce gpio usb extcon driver

[Chanwoo Choi]

Hi Roger,

We need to discuss one point about 'id_irqwake'.
I don't recommend to use 'id_irqwake' field.

And I catch build warning by using "select" keywork in Kconfig.
It is my wrong guide of "select" keyword. So, I'll change it 
as 'depends on' keyword.

Looks good to me except for 'id_irqwake'. 
I'll apply this patch on 3.21 queue after completing this discussion.

On 01/28/2015 09:15 PM, 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@xxxxxx>
> ---
> v3:
> - removed IRQF_NO_SUSPEND flag. Added IRQF_TRIGGER_RISING and
>   IRQF_TRIGGER_FALLING
> - Added disable_irq() to suspend() and enable_irq() to resume()
> 
>  .../devicetree/bindings/extcon/extcon-usb-gpio.txt |  18 ++
>  drivers/extcon/Kconfig                             |   7 +
>  drivers/extcon/Makefile                            |   1 +
>  drivers/extcon/extcon-usb-gpio.c                   | 233 +++++++++++++++++++++
>  4 files changed, 259 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
>  create mode 100644 drivers/extcon/extcon-usb-gpio.c
> 
> diff --git a/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt b/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
> new file mode 100644
> index 0000000..85fe6b0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
> @@ -0,0 +1,18 @@
> +USB GPIO 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-gpio"
> +- id-gpio: gpio for USB ID pin. See gpio binding.
> +
> +Example:
> +	extcon_usb1 {
> +		compatible = "linux,extcon-usb-gpio";
> +		id-gpio = <&gpio6 1 GPIO_ACTIVE_HIGH>;
> +	}
> +
> +	&omap_dwc3_1 {
> +		extcon = <&extcon_usb1>;
> +	};
> diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
> index 6a1f7de..fd11536 100644
> --- a/drivers/extcon/Kconfig
> +++ b/drivers/extcon/Kconfig
> @@ -93,4 +93,11 @@ config EXTCON_SM5502
>  	  Silicon Mitus SM5502. The SM5502 is a USB port accessory
>  	  detector and switch.
>  
> +config EXTCON_USB_GPIO
> +	tristate "USB GPIO extcon support"
> +	select GPIOLIB

I catch the build warning if using 'select' instead of 'depends on' as following:
It is my wrong guide to you. So, I'll modify it by using "depends on" as your original patch.

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- zImage  -j 8
scripts/kconfig/conf --silentoldconfig Kconfig
drivers/gpio/Kconfig:34:error: recursive dependency detected!
drivers/gpio/Kconfig:34:	symbol GPIOLIB is selected by EXTCON_USB_GPIO
drivers/extcon/Kconfig:96:	symbol EXTCON_USB_GPIO depends on EXTCON
drivers/extcon/Kconfig:1:	symbol EXTCON is selected by CHARGER_MANAGER
drivers/power/Kconfig:316:	symbol CHARGER_MANAGER depends on POWER_SUPPLY
drivers/power/Kconfig:1:	symbol POWER_SUPPLY is selected by HID_SONY
drivers/hid/Kconfig:670:	symbol HID_SONY depends on NEW_LEDS
drivers/leds/Kconfig:8:	symbol NEW_LEDS is selected by BCMA_DRIVER_GPIO
drivers/bcma/Kconfig:75:	symbol BCMA_DRIVER_GPIO 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.
> +
>  endif # MULTISTATE_SWITCH
> diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
> index 0370b42..6a08a98 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_USB_GPIO)	+= extcon-usb-gpio.o
> diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
> new file mode 100644
> index 0000000..99a58b2
> --- /dev/null
> +++ b/drivers/extcon/extcon-usb-gpio.c
> @@ -0,0 +1,233 @@
> +/**
> + * drivers/extcon/extcon-usb-gpio.c - USB GPIO extcon driver
> + *
> + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
> + * Author: Roger Quadros <rogerq@xxxxxx>
> + *
> + * 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/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;
> +	bool id_irqwake;		/* ID wakeup enabled flag */

Do you really think id_irqwake is necessary?
I think it is not necessary.

> +
> +	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,
> +};
> +

[snip]

> +
> +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 = dev_get_drvdata(dev);
> +
> +	if (device_may_wakeup(dev))
> +		if (!enable_irq_wake(info->id_irq))
> +			info->id_irqwake = true;
> +

You can simplify this code as following without 'id_irqwake':

	if (device_may_wakeup(dev))
		enable_irq_wake(info->id_irq);

> +	/*
> +	 * We don't want to process any IRQs after this point
> +	 * as GPIOs used behind I2C subsystem might not be
> +	 * accessible until resume completes. So disable IRQ.
> +	 */
> +	disable_irq(info->id_irq);
> +
> +	return 0;
> +}
> +
> +static int usb_extcon_resume(struct device *dev)
> +{
> +	struct usb_extcon_info *info = dev_get_drvdata(dev);
> +
> +	if (info->id_irqwake) {
> +		disable_irq_wake(info->id_irq);
> +		info->id_irqwake = false;
> +	}

ditto.

	if (device_may_wakeup(dev))
		disable_irq_wake(info->id_irq);

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

Thanks,
Chanwoo Choi

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