Date:	Mon, 27 Jun 2016 10:39:51 +0300
From:	Roger Quadros <rogerq@...com>
To:	Stephen Boyd <stephen.boyd@...aro.org>,
	Chanwoo Choi <cw00.choi@...sung.com>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] extcon: Add support for qcom SPMI PMIC USB id detection
 hardware

Hi Stephen,

On 26/06/16 08:56, Stephen Boyd wrote:
> Some Qualcomm PMICs have a misc device that performs USB id pin
> detection via an interrupt. When the interrupt triggers, we
> should read the interrupt line to see if it has gone high or low.
> If the interrupt is low then the ID pin is grounded, and if the
> interrupt is high then the ID pin is being held high.

Does this depend on any other drivers to configure the USB ID
interrupt or it works automatically once the interrupt is enabled?

> 
> Cc: Roger Quadros <rogerq@...com>
> Cc: Chanwoo Choi <cw00.choi@...sung.com>
> Signed-off-by: Stephen Boyd <stephen.boyd@...aro.org>
> ---
>  .../bindings/extcon/qcom,pm8941-misc.txt           |  41 +++++
>  drivers/extcon/Kconfig                             |   6 +
>  drivers/extcon/Makefile                            |   1 +
>  drivers/extcon/extcon-qcom-spmi-misc.c             | 170 +++++++++++++++++++++

Should we make this driver more generic so that it can support
any other platforms as well that can give USB ID over interrupt.

What about USB_VBUS? How is that delivered?

>  4 files changed, 218 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/extcon/qcom,pm8941-misc.txt
>  create mode 100644 drivers/extcon/extcon-qcom-spmi-misc.c
> 
> diff --git a/Documentation/devicetree/bindings/extcon/qcom,pm8941-misc.txt b/Documentation/devicetree/bindings/extcon/qcom,pm8941-misc.txt
> new file mode 100644
> index 000000000000..35383adb10f1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/extcon/qcom,pm8941-misc.txt
> @@ -0,0 +1,41 @@
> +Qualcomm's PM8941 USB ID Extcon device
> +
> +Some Qualcomm PMICs have a "misc" module that can be used to detect when
> +the USB ID pin has been pulled low or high.
> +
> +PROPERTIES
> +
> +- compatible:
> +    Usage: required
> +    Value type: <string>
> +    Definition: Should contain "qcom,pm8941-misc";
> +
> +- reg:
> +    Usage: required
> +    Value type: <u32>
> +    Definition: Should contain the offset to the misc address space
> +
> +- interrupts:
> +    Usage: required
> +    Value type: <prop-encoded-array>
> +    Definition: Should contain the usb id interrupt
> +
> +- interrupt-names:
> +    Usage: required
> +    Value type: <stringlist>
> +    Definition: Should contain the string "usb_id" for the usb id interrupt
> +
> +Example:
> +
> +	pmic {
> +		usb_id: misc@900 {
> +			compatible = "qcom,pm8941-misc";
> +			reg = <0x900>;
> +			interrupts = <0x0 0x9 0 IRQ_TYPE_EDGE_BOTH>;
> +			interrupt-names = "usb_id";
> +		};
> +	}
> +
> +	usb-controller {
> +		extcon = <&usb_id>;
> +	};
> diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
> index 3d89e60a3e71..b2ee47cb10ca 100644
> --- a/drivers/extcon/Kconfig
> +++ b/drivers/extcon/Kconfig
> @@ -119,6 +119,12 @@ config EXTCON_SM5502
>  	  Silicon Mitus SM5502. The SM5502 is a USB port accessory
>  	  detector and switch.
>  
> +config EXTCON_QCOM_SPMI_MISC
> +	tristate "Qualcomm USB extcon support"
> +	help
> +	  Say Y here to enable SPMI PMIC based USB cable detection
> +	  support on Qualcomm PMICs such as PM8941.
> +
>  config EXTCON_USB_GPIO
>  	tristate "USB GPIO extcon support"
>  	depends on GPIOLIB || COMPILE_TEST
> diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
> index 2a0e4f45d5b2..8cf6eb068d34 100644
> --- a/drivers/extcon/Makefile
> +++ b/drivers/extcon/Makefile
> @@ -15,4 +15,5 @@ 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-$(CONFIG_EXTCON_QCOM_SPMI_MISC) += extcon-qcom-spmi-misc.o
>  obj-$(CONFIG_EXTCON_USB_GPIO)	+= extcon-usb-gpio.o
> diff --git a/drivers/extcon/extcon-qcom-spmi-misc.c b/drivers/extcon/extcon-qcom-spmi-misc.c
> new file mode 100644
> index 000000000000..f0ec6f1541e1
> --- /dev/null
> +++ b/drivers/extcon/extcon-qcom-spmi-misc.c
> @@ -0,0 +1,170 @@
> +/**
> + * Based on extcon-usb-gpio.c
> + *
> + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
> + * Author: Roger Quadros <rogerq@...com>

You don't need to carry the original (C) here.

> + *
> + * Copyright (C) 2016 Linaro Ltd
> + *
> + * 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/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/workqueue.h>
> +
> +#define USB_ID_DEBOUNCE_MS	5	/* ms */
> +
> +struct qcom_usb_extcon_info {
> +	struct extcon_dev *edev;
> +	int irq;
> +	struct delayed_work wq_detcable;
> +	unsigned long debounce_jiffies;
> +};
> +
> +static const unsigned int qcom_usb_extcon_cable[] = {
> +	EXTCON_USB_HOST,
> +	EXTCON_NONE,
> +};
> +
> +static void qcom_usb_extcon_detect_cable(struct work_struct *work)
> +{
> +	bool id;
> +	int ret;
> +	struct qcom_usb_extcon_info *info = container_of(to_delayed_work(work),
> +						    struct qcom_usb_extcon_info,
> +						    wq_detcable);
> +
> +	/* check ID and update cable state */
> +	ret = irq_get_irqchip_state(info->irq, IRQCHIP_STATE_LINE_LEVEL, &id);
> +	if (ret)
> +		return;
> +
> +	extcon_set_cable_state_(info->edev, EXTCON_USB_HOST, !id);
> +}
> +
> +static irqreturn_t qcom_usb_irq_handler(int irq, void *dev_id)
> +{
> +	struct qcom_usb_extcon_info *info = dev_id;
> +
> +	queue_delayed_work(system_power_efficient_wq, &info->wq_detcable,
> +			   info->debounce_jiffies);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int qcom_usb_extcon_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct qcom_usb_extcon_info *info;
> +	int ret;
> +
> +	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
> +	if (!info)
> +		return -ENOMEM;
> +
> +	info->edev = devm_extcon_dev_allocate(dev, qcom_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;
> +	}
> +
> +	info->debounce_jiffies = msecs_to_jiffies(USB_ID_DEBOUNCE_MS);
> +	INIT_DELAYED_WORK(&info->wq_detcable, qcom_usb_extcon_detect_cable);
> +
> +	info->irq = platform_get_irq_byname(pdev, "usb_id");
> +	if (info->irq < 0)
> +		return info->irq;
> +
> +	ret = devm_request_threaded_irq(dev, info->irq, NULL,
> +					qcom_usb_irq_handler,
> +					IRQF_TRIGGER_RISING |
> +					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> +					pdev->name, info);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to request handler for ID IRQ\n");
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, info);
> +	device_init_wakeup(dev, 1);
> +
> +	/* Perform initial detection */
> +	qcom_usb_extcon_detect_cable(&info->wq_detcable.work);
> +
> +	return 0;
> +}
> +
> +static int qcom_usb_extcon_remove(struct platform_device *pdev)
> +{
> +	struct qcom_usb_extcon_info *info = platform_get_drvdata(pdev);
> +
> +	cancel_delayed_work_sync(&info->wq_detcable);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int qcom_usb_extcon_suspend(struct device *dev)
> +{
> +	struct qcom_usb_extcon_info *info = dev_get_drvdata(dev);
> +	int ret = 0;
> +
> +	if (device_may_wakeup(dev))
> +		ret = enable_irq_wake(info->irq);
> +
> +	return ret;
> +}
> +
> +static int qcom_usb_extcon_resume(struct device *dev)
> +{
> +	struct qcom_usb_extcon_info *info = dev_get_drvdata(dev);
> +	int ret = 0;
> +
> +	if (device_may_wakeup(dev))
> +		ret = disable_irq_wake(info->irq);
> +
> +	return ret;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(qcom_usb_extcon_pm_ops,
> +			 qcom_usb_extcon_suspend, qcom_usb_extcon_resume);
> +
> +static const struct of_device_id qcom_usb_extcon_dt_match[] = {
> +	{ .compatible = "qcom,pm8941-misc", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, qcom_usb_extcon_dt_match);
> +
> +static struct platform_driver qcom_usb_extcon_driver = {
> +	.probe		= qcom_usb_extcon_probe,
> +	.remove		= qcom_usb_extcon_remove,
> +	.driver		= {
> +		.name	= "extcon-pm8941-misc",
> +		.pm	= &qcom_usb_extcon_pm_ops,
> +		.of_match_table = qcom_usb_extcon_dt_match,
> +	},
> +};
> +module_platform_driver(qcom_usb_extcon_driver);
> +
> +MODULE_DESCRIPTION("QCOM USB ID extcon driver");
> +MODULE_LICENSE("GPL v2");
> 

--
cheers,
-roger

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