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Message-id: <54CACC28.3050306@samsung.com>
Date: Fri, 30 Jan 2015 09:11:20 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: Roger Quadros <rogerq@...com>
Cc: myungjoo.ham@...sung.com, balbi@...com, tony@...mide.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 v3 1/7] extcon: usb-gpio: Introduce gpio usb extcon driver
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@...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@...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.
[snip]
Thanks,
Chanwoo Choi
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