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

[Chanwoo Choi <cw00.choi@samsung.com>]

Hi Roger,

On 01/30/2015 11:03 PM, Roger Quadros wrote:
> On 30/01/15 02:11, Chanwoo Choi wrote:
>> Hi Roger,
>>
>> 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@ti.com>
>>> ---
>>> 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
>>> +	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@ti.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/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 */
>>> +
>>> +	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",
>>
>> I'll use the defined name for extcon cable name as soon because 
>> it has potential isseu about the conflict of extcon cable name between subsystems.
>> So, I recommend to use a captical letter as "USB-HOST" instead of "USB-Host".
>> If other extcon driver don't use the captical letter, I'll fix it.
> 
> Did you see patch 2 in this series?
> In that I had fixed all instances to use "USB-Host" based on
> http://lxr.free-electrons.com/source/drivers/extcon/extcon-class.c#L45
> 
> What do you suggest?
> Skip patch 2 and convert all "USB-Host" to "USB-HOST"?

I replied my opinion about this on following patch[1].
[1] Re: [PATCH v2 2/7] usb: extcon: Fix USB-Host cable name

Thanks,
Chanwoo Choi