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Date:	Thu, 19 Mar 2015 14:20:17 +0530
From:	George Cherian <gcherianv@...il.com>
To:	Robert Baldyga <r.baldyga@...sung.com>
Cc:	balbi@...com, gregkh@...uxfoundation.org, myungjoo.ham@...sung.com,
	cw00.choi@...sung.com, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, m.szyprowski@...sung.com,
	Łukasz Stelmach <l.stelmach@...sung.com>
Subject: Re: [RFC 01/19] extcon: add extcon-odroid-usbotg driver

Hi Robert,

This looks like a extcon driver based on gpio for USB.

Roger posted a generic one a while back.
https://lkml.org/lkml/2015/2/2/187

Doesn't this serve the purpose rather than adding this driver?

-George

On Wed, Mar 18, 2015 at 7:34 PM, Robert Baldyga <r.baldyga@...sung.com> wrote:
> This patch adds extcon driver for Odroid U3, U3+ and X boards.
> It recognizes type of USB cable connected to Odroid board basing on
> two signal lines VBUS_DET and OTG_ID (the second one is present only
> on Odroid U3+ board).
>
> Following table of states presents relationship between this signals
> and detected cable type:
>
> state    | VBUS_DET |  OTG_ID
> -------------------------------
> USB      |    H     |    H
> USB_HOST |    H     |    L
> disconn. |    L     |    H
> USB-HOST |    L     |    L
>
> This driver is based on extcon-gpio driver.
>
> Signed-off-by: Łukasz Stelmach <l.stelmach@...sung.com>
> Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>
> ---
>  drivers/extcon/Kconfig                |   4 +
>  drivers/extcon/Makefile               |   1 +
>  drivers/extcon/extcon-odroid-usbotg.c | 256 ++++++++++++++++++++++++++++++++++
>  3 files changed, 261 insertions(+)
>  create mode 100644 drivers/extcon/extcon-odroid-usbotg.c
>
> diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
> index 6a1f7de..891dca3 100644
> --- a/drivers/extcon/Kconfig
> +++ b/drivers/extcon/Kconfig
> @@ -93,4 +93,8 @@ config EXTCON_SM5502
>           Silicon Mitus SM5502. The SM5502 is a USB port accessory
>           detector and switch.
>
> +config EXTCON_ODROID_USBOTG
> +       tristate "Extcon Odroid U3, U3+, X and XU USB OTG port"
> +       depends on OF_GPIO
> +
>  endif # MULTISTATE_SWITCH
> diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
> index 0370b42..514384e 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_ODROID_USBOTG) += extcon-odroid-usbotg.o
> diff --git a/drivers/extcon/extcon-odroid-usbotg.c b/drivers/extcon/extcon-odroid-usbotg.c
> new file mode 100644
> index 0000000..7f71c48
> --- /dev/null
> +++ b/drivers/extcon/extcon-odroid-usbotg.c
> @@ -0,0 +1,256 @@
> +/*
> + *  drivers/extcon/extcon-odroid-usbotg.c
> + *
> + *  USB cable extcon driver for Odroid U3, Odroid U3+ and Odroid X
> + *
> + * Copyright (C) 2014 Samsung Electronics
> + * Author: Lukasz Stelmach <l.stelmach@...sung.com>
> + * Author: Robert Baldyga <r.baldyga@...sung.com>
> + *
> + * based on drivers/extcon/extcon-gpio.c
> + * Copyright (C) 2008 Google, Inc.
> + * Author: Mike Lockwood <lockwood@...roid.com>
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * 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/module.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/gpio.h>
> +#include <linux/of_gpio.h>
> +#include <linux/extcon.h>
> +#include <linux/extcon/extcon-gpio.h>
> +#include <linux/delay.h>
> +
> +enum {
> +       EXTCON_CABLE_USB = 0,
> +       EXTCON_CABLE_USB_HOST,
> +
> +       _EXTCON_CABLE_NUM,
> +};
> +
> +static const char * const odroid_usbotg_cable[] = {
> +       [EXTCON_CABLE_USB] = "USB",
> +       [EXTCON_CABLE_USB_HOST] = "USB-HOST",
> +
> +       NULL,
> +};
> +
> +struct odroid_usbotg_data {
> +       struct extcon_dev *edev;
> +       struct gpio_desc *otg_id;
> +       struct gpio_desc *vbus_det;
> +       int otg_id_irq;
> +       int vbus_det_irq;
> +       unsigned long debounce_ms;
> +};
> +
> +/*
> + * state    | VBUS_DET |  OTG_ID
> + * -------------------------------
> + * USB      |    H     |    H
> + * USB-HOST |    H     |    L
> + * disconn. |    L     |    H
> + * USB-HOST |    L     |    L
> + *
> + * Only Odroid U3+ has OTG_ID line. U3 and X versions can detect only
> + * USB slave cable.
> + */
> +
> +static void odroid_usbotg_detect_cable(struct odroid_usbotg_data *extcon_data)
> +{
> +       int state;
> +
> +       mdelay(extcon_data->debounce_ms);
> +
> +       if (extcon_data->otg_id)
> +               state = (gpiod_get_value(extcon_data->vbus_det) << 1) |
> +                       gpiod_get_value(extcon_data->otg_id);
> +       else
> +               state = (gpiod_get_value(extcon_data->vbus_det) << 1) | 1;
> +
> +       dev_dbg(&extcon_data->edev->dev, "cable state changed to %d\n", state);
> +
> +       if (state & 0x1)
> +               extcon_set_cable_state_(extcon_data->edev,
> +                       EXTCON_CABLE_USB_HOST, false);
> +       if (state != 0x3)
> +               extcon_set_cable_state_(extcon_data->edev,
> +                       EXTCON_CABLE_USB, false);
> +
> +       if (!(state & 0x1))
> +               extcon_set_cable_state_(extcon_data->edev,
> +                       EXTCON_CABLE_USB_HOST, true);
> +       else if (state == 0x3)
> +               extcon_set_cable_state_(extcon_data->edev,
> +                       EXTCON_CABLE_USB, true);
> +}
> +
> +static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
> +{
> +       struct odroid_usbotg_data *extcon_data = dev_id;
> +
> +       odroid_usbotg_detect_cable(extcon_data);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static int odroid_usbotg_parse_dt(struct platform_device *pdev,
> +                                   struct odroid_usbotg_data *extcon_data)
> +{
> +       struct device_node *np = pdev->dev.of_node;
> +       u32 val;
> +
> +       if (!np)
> +               return -ENODEV;
> +
> +       extcon_data->edev->name = np->name;
> +
> +       if (of_property_read_u32(np, "debounce", &val) != 0)
> +               val = 50;
> +       extcon_data->debounce_ms = val;
> +
> +       return 0;
> +}
> +
> +static int odroid_usbotg_probe(struct platform_device *pdev)
> +{
> +       struct odroid_usbotg_data *extcon_data;
> +       int ret = 0;
> +
> +       extcon_data = devm_kzalloc(&pdev->dev,
> +               sizeof(struct odroid_usbotg_data), GFP_KERNEL);
> +       if (!extcon_data)
> +               return -ENOMEM;
> +
> +       extcon_data->edev = devm_kzalloc(&pdev->dev, sizeof(struct extcon_dev),
> +                                        GFP_KERNEL);
> +       if (IS_ERR(extcon_data->edev)) {
> +               dev_err(&pdev->dev, "failed to allocate extcon device\n");
> +               return -ENOMEM;
> +       }
> +       extcon_data->edev->supported_cable = odroid_usbotg_cable;
> +
> +       ret = odroid_usbotg_parse_dt(pdev, extcon_data);
> +       if (IS_ERR_VALUE(ret)) {
> +               dev_err(&pdev->dev, "failed to get data from device tree\n");
> +               return ret;
> +       }
> +
> +       /* gpios */
> +       extcon_data->vbus_det = devm_gpiod_get(&pdev->dev, "vbus-det");
> +       if (IS_ERR(extcon_data->vbus_det)) {
> +               dev_err(&pdev->dev, "failed to get vbus_det gpio\n");
> +               return PTR_ERR(extcon_data->vbus_det);
> +       }
> +       extcon_data->otg_id = devm_gpiod_get_optional(&pdev->dev, "otg-id");
> +
> +       extcon_data->edev->dev.parent = &pdev->dev;
> +       ret = extcon_dev_register(extcon_data->edev);
> +       if (ret < 0)
> +               return ret;
> +
> +       /* irq */
> +       extcon_data->vbus_det_irq = gpiod_to_irq(extcon_data->vbus_det);
> +       if (extcon_data->vbus_det_irq < 0) {
> +               dev_err(&pdev->dev, "failed to get irq from vbus_det\n");
> +               ret = extcon_data->vbus_det_irq;
> +               goto err;
> +       }
> +       ret = request_threaded_irq(extcon_data->vbus_det_irq, NULL,
> +                                  gpio_irq_handler, IRQF_ONESHOT |
> +                                  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
> +                                  pdev->name, extcon_data);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "failed to request vbus_det irq\n");
> +               goto err;
> +       }
> +
> +       if (extcon_data->otg_id) {
> +               extcon_data->otg_id_irq = gpiod_to_irq(extcon_data->otg_id);
> +               if (extcon_data->otg_id_irq < 0) {
> +                       dev_err(&pdev->dev, "failed to get irq from otg_id\n");
> +                       ret = extcon_data->otg_id_irq;
> +                       goto err;
> +               }
> +               ret = request_threaded_irq(extcon_data->otg_id_irq, NULL,
> +                               gpio_irq_handler, IRQF_ONESHOT |
> +                               IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
> +                               pdev->name, extcon_data);
> +               if (ret < 0) {
> +                       dev_err(&pdev->dev, "failed to request otg_id irq\n");
> +                       goto err;
> +               }
> +       }
> +
> +       platform_set_drvdata(pdev, extcon_data);
> +       /* Perform initial detection */
> +       odroid_usbotg_detect_cable(extcon_data);
> +
> +       dev_dbg(&pdev->dev, "probe: success\n");
> +
> +       return 0;
> +
> +err:
> +       extcon_dev_unregister(extcon_data->edev);
> +
> +       return ret;
> +}
> +
> +static int odroid_usbotg_remove(struct platform_device *pdev)
> +{
> +       struct odroid_usbotg_data *extcon_data = platform_get_drvdata(pdev);
> +
> +       free_irq(extcon_data->vbus_det_irq, extcon_data);
> +       if (extcon_data->otg_id)
> +               free_irq(extcon_data->otg_id_irq, extcon_data);
> +       extcon_dev_unregister(extcon_data->edev);
> +
> +       return 0;
> +}
> +
> +static const struct of_device_id odroid_usbotg_of_match[] = {
> +       { .compatible = "extcon-odroid-usbotg" },
> +       { },
> +};
> +MODULE_DEVICE_TABLE(of, odroid_usbotg_of_match);
> +
> +static struct platform_driver odroid_usbotg_driver = {
> +       .probe          = odroid_usbotg_probe,
> +       .remove         = odroid_usbotg_remove,
> +       .driver         = {
> +               .name   = "odroid-usbotg",
> +               .owner  = THIS_MODULE,
> +               .of_match_table = of_match_ptr(odroid_usbotg_of_match)
> +       },
> +};
> +
> +static int __init odroid_usbotg_init(void)
> +{
> +       return platform_driver_register(&odroid_usbotg_driver);
> +}
> +
> +subsys_initcall(odroid_usbotg_init);
> +
> +static void __exit odroid_usbotg_cleanup(void)
> +{
> +       platform_driver_unregister(&odroid_usbotg_driver);
> +}
> +
> +module_exit(odroid_usbotg_cleanup);
> +
> +MODULE_AUTHOR("Lukasz Stelmach <l.stelmach@...sung.com>, Robert Baldyga <r.baldyga@...sung.com>");
> +MODULE_DESCRIPTION("USB OTG extcon driver for Odroid U3, U3+ and X");
> +MODULE_LICENSE("GPL");
> --
> 1.9.1
>
> --
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