Re: [PATCH v2 1/7] extcon: usb-gpio: Introduce gpio usb extcon driver

[Chanwoo Choi <cwchoi00@gmail.com>]

Hi Roger,

This patch looks good to me. But I add some comment.
If you modify some comment, I'll apply this patch on 3.21 queue.

On Mon, Jan 26, 2015 at 9:15 PM, Roger Quadros <rogerq@ti.com> 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>
> ---
>  .../devicetree/bindings/extcon/extcon-usb-gpio.txt |  20 ++
>  drivers/extcon/Kconfig                             |   7 +
>  drivers/extcon/Makefile                            |   1 +
>  drivers/extcon/extcon-usb-gpio.c                   | 214 +++++++++++++++++++++
>  4 files changed, 242 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..ab52a85
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
> @@ -0,0 +1,20 @@
> +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>;
> +       }
> +
> +       usb@1 {
> +               ...
> +               extcon = <&extcon_usb1>;
> +               ...

I don' want to use '...' for example.
How about using omap usecase in your patch4[1] as following?
[1] ARM: dts: dra72-evm: Add extcon nodes for USB

            &omap_dwc3_1 {
                        extcon = <&extcon_usb1>;
            };

> +       };
> diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
> index 6a1f7de..e4c01ab 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"
> +       depends on GPIOLIB

How about use 'select' keyword instead of 'depends on'?
- depends on GPIOLIB -> 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..a20aa39
> --- /dev/null
> +++ b/drivers/extcon/extcon-usb-gpio.c
> @@ -0,0 +1,214 @@
> +/**
> + * drivers/extcon/extcon_usb_gpio.c - USB GPIO extcon driver

You should use the '-' instead of '_'.
- s/extcon_usb_gpio.c/extcon-usb-gpio.c

> + *
> + * 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;
> +
> +       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;
> +
> +       info  = container_of(to_delayed_work(work), struct usb_extcon_info,
> +                            wq_detcable);

Simplify container_of statement as following:
            struct usb_extcon_info *info  = container_of(to_delayed_work(work),
                                                                struct
usb_extcon_info, wq_detcable);

> +
> +       /* 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,
> +                                      usb_extcon_cable[EXTCON_CABLE_USB_HOST],
> +                                      false);
> +               extcon_set_cable_state(info->edev,
> +                                      usb_extcon_cable[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,
> +                                      usb_extcon_cable[EXTCON_CABLE_USB],
> +                                      false);
> +               extcon_set_cable_state(info->edev,
> +                                      usb_extcon_cable[EXTCON_CABLE_USB_HOST],
> +                                      true);
> +       }
> +}
> +
> +static irqreturn_t usb_irq_handler(int irq, void *dev_id)
> +{
> +       struct usb_extcon_info *info = dev_id;
> +
> +       queue_delayed_work(system_power_efficient_wq, &info->wq_detcable,
> +                          info->debounce_jiffies);

Need to add blank line.

> +       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(*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 |
> +                                       IRQF_NO_SUSPEND,
> +                                       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 register extcon device\n");
> +               return ret;
> +       }
> +
> +       platform_set_drvdata(pdev, info);

I prefer to execute the device_init_wakeup() function as following
for suspend/resume function:
            device_init_wakeup(&pdev->dev, 1);

> +
> +       /* 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);

Need to add blank line.

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

I prefer to use device_may_wakeup() function for whether
executing enable_irq_wake() or not. Also, The disable_irq()
in the suspend function would prevent us from discarding interrupt
before wakeup from suspend completely.

            if (device_may_wakeup(dev))
                     enable_irq_wake(info->id_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);
> +
> +       disable_irq_wake(info->id_irq);

ditto as following:

            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", },
> +       { /* end */ }

I prefer to use 'sentinel' word instead of 'end'

> +};
> +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@ti.com>");
> +MODULE_DESCRIPTION("USB GPIO extcon driver");
> +MODULE_LICENSE("GPL v2");

Thanks,
Chanwoo Choi