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    From: anish kumar <anish198519851985@gmail.com>

    External connector devices that decides connection information based on
    ADC values may use adc-jack device driver. The user simply needs to
    provide a table of adc range and connection states. Then, extcon
    framework will automatically notify others.

    Changes in this version:
    added Lars-Peter Clausen suggested changes:
    Using macros to get rid of boiler plate code such as devm_kzalloc
    and module_platform_driver.Other changes suggested are related to
    coding guidelines.

    Signed-off-by: anish kumar <anish.singh@samsung.com>
    Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
    ---
    drivers/extcon/Kconfig | 5 +
    drivers/extcon/Makefile | 1 +
    drivers/extcon/adc_jack.c | 193 +++++++++++++++++++++++++++++++++++++++
    include/linux/extcon/adc_jack.h | 77 ++++++++++++++++
    4 files changed, 276 insertions(+), 0 deletions(-)
    create mode 100644 drivers/extcon/adc_jack.c
    create mode 100644 include/linux/extcon/adc_jack.h

    diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
    index e175c8e..596e277 100644
    --- a/drivers/extcon/Kconfig
    +++ b/drivers/extcon/Kconfig
    @@ -21,6 +21,11 @@ config EXTCON_GPIO
    Say Y here to enable GPIO based extcon support. Note that GPIO
    extcon supports single state per extcon instance.

    +config EXTCON_ADC_JACK
    + tristate "ADC Jack extcon support"
    + help
    + Say Y here to enable extcon device driver based on ADC values.
    +
    config EXTCON_MAX77693
    tristate "MAX77693 EXTCON Support"
    depends on MFD_MAX77693
    diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
    index 88961b3..d95c5ea 100644
    --- a/drivers/extcon/Makefile
    +++ b/drivers/extcon/Makefile
    @@ -4,6 +4,7 @@

    obj-$(CONFIG_EXTCON) += extcon_class.o
    obj-$(CONFIG_EXTCON_GPIO) += extcon_gpio.o
    +obj-$(CONFIG_EXTCON_ADC_JACK) += adc_jack.o
    obj-$(CONFIG_EXTCON_MAX77693) += extcon-max77693.o
    obj-$(CONFIG_EXTCON_MAX8997) += extcon-max8997.o
    obj-$(CONFIG_EXTCON_ARIZONA) += extcon-arizona.o
    diff --git a/drivers/extcon/adc_jack.c b/drivers/extcon/adc_jack.c
    new file mode 100644
    index 0000000..8b80af0
    --- /dev/null
    +++ b/drivers/extcon/adc_jack.c
    @@ -0,0 +1,193 @@
    +/*
    + * drivers/extcon/adc_jack.c
    + *
    + * Analog Jack extcon driver with ADC-based detection capability.
    + *
    + * Copyright (C) 2012 Samsung Electronics
    + * MyungJoo Ham <myungjoo.ham@samsung.com>
    + *
    + * Modified for calling to IIO to get adc by <anish.singh@samsung.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.
    + *
    + */
    +
    +#include <linux/slab.h>
    +#include <linux/device.h>
    +#include <linux/platform_device.h>
    +#include <linux/interrupt.h>
    +#include <linux/workqueue.h>
    +#include <linux/iio/consumer.h>
    +#include <linux/extcon/adc_jack.h>
    +#include <linux/extcon.h>
    +
    +/**
    + * struct adc_jack_data - internal data for adc_jack device driver
    + * @edev - extcon device.
    + * @cable_names - list of supported cables.
    + * @num_cables - size of cable_names.
    + * @adc_condition - list of adc value conditions.
    + * @num_condition - size of adc_condition.
    + * @irq - irq number of attach/detach event (0 if not exist).
    + * @handling_delay - interrupt handler will schedule extcon event
    + * handling at handling_delay jiffies.
    + * @handler - extcon event handler called by interrupt handler.
    + * @get_adc - a callback to get ADC value to identify state.
    + */
    +struct adc_jack_data {
    + struct extcon_dev edev;
    +
    + const char **cable_names;
    + int num_cables;
    + struct adc_jack_cond *adc_condition;
    + int num_conditions;
    +
    + int irq;
    + unsigned long handling_delay; /* in jiffies */
    + struct delayed_work handler;
    +
    + struct iio_channel *chan;
    +};
    +
    +static void adc_jack_handler(struct work_struct *work)
    +{
    + struct adc_jack_data *data = container_of(to_delayed_work(work),
    + struct adc_jack_data,
    + handler);
    + u32 state = 0;
    + int ret, adc_val;
    + int i;
    +
    + ret = iio_read_channel_raw(data->chan, &adc_val);
    + if (ret < 0) {
    + dev_err(data->edev.dev, "read channel() error: %d\n", ret);
    + return;
    + }
    +
    + /* Get state from adc value with adc_condition */
    + for (i = 0; i < data->num_conditions; i++) {
    + struct adc_jack_cond *def = &data->adc_condition[i];
    + if (!def->state)
    + break;
    + if (def->min_adc <= adc_val && def->max_adc >= adc_val) {
    + state = def->state;
    + break;
    + }
    + }
    + /* if no def has met, it means state = 0 (no cables attached) */
    +
    + extcon_set_state(&data->edev, state);
    +}
    +
    +static irqreturn_t adc_jack_irq_thread(int irq, void *_data)
    +{
    + struct adc_jack_data *data = _data;
    +
    + schedule_delayed_work(&data->handler, data->handling_delay);
    + return IRQ_HANDLED;
    +}
    +
    +static int adc_jack_probe(struct platform_device *pdev)
    +{
    + struct adc_jack_data *data;
    + struct adc_jack_pdata *pdata = pdev->dev.platform_data;
    + int i, err = 0;
    +
    + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
    + if (!data)
    + return -ENOMEM;
    +
    + data->edev.name = pdata->name;
    +
    + if (pdata->cable_names)
    + data->edev.supported_cable = pdata->cable_names;
    + else
    + data->edev.supported_cable = extcon_cable_name;
    +
    + /* Check the length of array and set num_cables */
    + for (i = 0; data->edev.supported_cable[i]; i++)
    + ;
    + if (i == 0 || i > SUPPORTED_CABLE_MAX) {
    + err = -EINVAL;
    + dev_err(&pdev->dev, "error: pdata->cable_names size = %d\n",
    + i - 1);
    + goto err_alloc;
    + }
    + data->num_cables = i;
    +
    + if (!pdata->adc_condition ||
    + !pdata->adc_condition[0].state) {
    + err = -EINVAL;
    + dev_err(&pdev->dev, "error: adc_condition not defined.\n");
    + goto err_alloc;
    + }
    + data->adc_condition = pdata->adc_condition;
    +
    + /* Check the length of array and set num_conditions */
    + for (i = 0; data->adc_condition[i].state; i++)
    + ;
    + data->num_conditions = i;
    +
    + data->chan = iio_channel_get(dev_name(&pdev->dev),
    + pdata->consumer_channel);
    + if (IS_ERR(data->chan)) {
    + err = PTR_ERR(data->chan);
    + goto err_alloc;
    + }
    +
    + data->handling_delay = msecs_to_jiffies(pdata->handling_delay_ms);
    +
    + INIT_DELAYED_WORK_DEFERRABLE(&data->handler, adc_jack_handler);
    +
    + platform_set_drvdata(pdev, data);
    +
    + err = extcon_dev_register(&data->edev, &pdev->dev);
    + if (err)
    + goto err_initwork;
    +
    + data->irq = platform_get_irq(pdev, 0);
    +
    + err = request_any_context_irq(data->irq, adc_jack_irq_thread,
    + pdata->irq_flags, pdata->name, data);
    +
    + if (err) {
    + dev_err(&pdev->dev, "error: irq %d\n", data->irq);
    + err = -EINVAL;
    + goto err_irq;
    + }
    +
    + goto out;
    +
    +err_irq:
    + extcon_dev_unregister(&data->edev);
    +err_initwork:
    + cancel_delayed_work_sync(&data->handler);
    +err_alloc:
    + kfree(data);
    +out:
    + return err;
    +}
    +
    +static int __devexit adc_jack_remove(struct platform_device *pdev)
    +{
    + struct adc_jack_data *data = platform_get_drvdata(pdev);
    +
    + extcon_dev_unregister(&data->edev);
    + if (data->irq)
    + free_irq(data->irq, data);
    +
    + return 0;
    +}
    +
    +static struct platform_driver adc_jack_driver = {
    + .probe = adc_jack_probe,
    + .remove = __devexit_p(adc_jack_remove),
    + .driver = {
    + .name = "adc-jack",
    + .owner = THIS_MODULE,
    + },
    +};
    +
    +module_platform_driver(adc_jack_driver);
    diff --git a/include/linux/extcon/adc_jack.h b/include/linux/extcon/adc_jack.h
    new file mode 100644
    index 0000000..ca4d1cd
    --- /dev/null
    +++ b/include/linux/extcon/adc_jack.h
    @@ -0,0 +1,77 @@
    +/*
    + * include/linux/extcon/adc_jack.h
    + *
    + * Analog Jack extcon driver with ADC-based detection capability.
    + *
    + * Copyright (C) 2012 Samsung Electronics
    + * MyungJoo Ham <myungjoo.ham@samsung.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.
    + *
    + */
    +
    +#ifndef _EXTCON_ADC_JACK_H_
    +#define _EXTCON_ADC_JACK_H_ __FILE__
    +
    +#include <linux/module.h>
    +#include <linux/extcon.h>
    +
    +/**
    + * struct adc_jack_cond - condition to use an extcon state
    + * @state - the corresponding extcon state (if 0, this struct denotes
    + * the last adc_jack_cond element among the array)
    + * @min_adc - min adc value for this condition
    + * @max_adc - max adc value for this condition
    + *
    + * For example, if { .state = 0x3, .min_adc = 100, .max_adc = 200}, it means
    + * that if ADC value is between (inclusive) 100 and 200, than the cable 0 and
    + * 1 are attached (1<<0 | 1<<1 == 0x3)
    + *
    + * Note that you don't need to describe condition for "no cable attached"
    + * because when no adc_jack_cond is met, state = 0 is automatically chosen.
    + */
    +struct adc_jack_cond {
    + u32 state; /* extcon state value. 0 if invalid */
    + u32 min_adc;
    + u32 max_adc;
    +};
    +
    +/**
    + * struct adc_jack_pdata - platform data for adc jack device.
    + * @name - name of the extcon device. If null, "adc-jack" is used.
    + * @cable_names - array of cable names ending with null. If the array itself
    + * if null, extcon standard cable names are chosen.
    + * @adc_contition - array of struct adc_jack_cond conditions ending
    + * with .state = 0 entry. This describes how to decode
    + * adc values into extcon state.
    + * @irq - IRQ number that is triggerred by cable attach/detach
    + * events. If irq = 0, use should manually update extcon state
    + * with extcon APIs.
    + * @irq_flags - irq flags used for the @irq
    + * @handling_delay_ms - in some devices, we need to read ADC value some
    + * milli-seconds after the interrupt occurs. You may
    + * describe such delays with @handling_delay_ms, which
    + * is rounded-off by jiffies.
    + * @get_adc - the callback to read ADC value to identify cable states.
    + */
    +struct adc_jack_pdata {
    + const char *name;
    + const char *consumer_channel;
    + /*
    + * NULL if standard extcon names are used.
    + * The last entry should be NULL
    + */
    + const char **cable_names;
    + /* The last entry's state should be 0 */
    + struct adc_jack_cond *adc_condition;
    +
    + unsigned long irq_flags;
    + unsigned long handling_delay_ms; /* in ms */
    +
    + /* When we have ADC subsystem, this can be generalized. */
    + int (*get_adc)(u32 *value);
    +};
    +
    +#endif /* _EXTCON_ADC_JACK_H */
    --
    1.7.1


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