extcon: adc_jack: adc-jack driver to support 3.5 pi or simliar devices

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 V1:
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.

Changes in V2:
Removed some unnecessary checks and changed the way we are un-regitering
extcon and freeing the irq while removing.

Changes in V3:
Renamed the files to comply with extcon naming.

Changes in V4:
Added the cancel_work_sync during removing of driver.

Changes in V5:
Added the dependency of IIO in Kconfig.

Changes in V6:
Some nitpicks related to naming.

Changes in this version:
V6 patch version patch broke the build:
ERROR: "extcon_cable_name" [drivers/extcon/extcon-adc-jack.ko] undefined!

Fixed it in this version.

Acked-by: Jonathan Cameron <jic23@kernel.org>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: anish kumar <anish.singh@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 276 insertions, 0 deletions

diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
index e175c8ed4ec4..dd5b01b957aa 100644
--- a/drivers/extcon/Kconfig
+++ b/drivers/extcon/Kconfig
@@ -21,6 +21,12 @@ 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"
+        depends on IIO
+        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 9c0682daefb8..f98a3c4d46e0 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-$(CONFIG_EXTCON_ADC_JACK)   += extcon-adc-jack.o
 obj-$(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/extcon-adc-jack.c b/drivers/extcon/extcon-adc-jack.c
new file mode 100644
index 000000000000..60ac3fbb4cde
--- /dev/null
+++ b/drivers/extcon/extcon-adc-jack.c
@@ -0,0 +1,198 @@
+/*
+ * drivers/extcon/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/err.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/iio/consumer.h>
+#include <linux/extcon/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_conditions       - list of adc value conditions.
+ * @num_conditions       - size of adc_conditions.
+ * @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.
+ * @chan       - iio channel being queried.
+ */
+struct adc_jack_data {
+        struct extcon_dev edev;
+
+        const char **cable_names;
+        int num_cables;
+        struct adc_jack_cond *adc_conditions;
+        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_conditions */
+        for (i = 0; i < data->num_conditions; i++) {
+                struct adc_jack_cond *def = &data->adc_conditions[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 __devinit 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) {
+                err = -EINVAL;
+                dev_err(&pdev->dev, "error: cable_names not defined.\n");
+                goto out;
+        }
+
+        data->edev.supported_cable = pdata->cable_names;
+
+        /* 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 out;
+        }
+        data->num_cables = i;
+
+        if (!pdata->adc_conditions ||
+                        !pdata->adc_conditions[0].state) {
+                err = -EINVAL;
+                dev_err(&pdev->dev, "error: adc_conditions not defined.\n");
+                goto out;
+        }
+        data->adc_conditions = pdata->adc_conditions;
+
+        /* Check the length of array and set num_conditions */
+        for (i = 0; data->adc_conditions[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 out;
+        }
+
+        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 out;
+
+        data->irq = platform_get_irq(pdev, 0);
+        if (!data->irq) {
+                dev_err(&pdev->dev, "platform_get_irq failed\n");
+                err = -ENODEV;
+                goto err_irq;
+        }
+
+        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);
+out:
+        return err;
+}
+
+static int __devexit adc_jack_remove(struct platform_device *pdev)
+{
+        struct adc_jack_data *data = platform_get_drvdata(pdev);
+
+        free_irq(data->irq, data);
+        cancel_work_sync(&data->handler.work);
+        extcon_dev_unregister(&data->edev);
+
+        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/extcon-adc-jack.h b/include/linux/extcon/extcon-adc-jack.h
new file mode 100644
index 000000000000..20e9eef25d4c
--- /dev/null
+++ b/include/linux/extcon/extcon-adc-jack.h
@@ -0,0 +1,71 @@
+/*
+ * include/linux/extcon/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.
+ * @consumer_channel - Unique name to identify the channel on the consumer
+ *                   side. This typically describes the channels used within
+ *                   the consumer. E.g. 'battery_voltage'
+ * @cable_names        - array of cable names ending with null.
+ * @adc_contitions     - array of struct adc_jack_cond conditions ending
+ *                     with .state = 0 entry. This describes how to decode
+ *                     adc values into extcon state.
+ * @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.
+ */
+struct adc_jack_pdata {
+        const char *name;
+        const char *consumer_channel;
+        /*
+         * The last entry should be NULL
+         */
+        const char **cable_names;
+        /* The last entry's state should be 0 */
+        struct adc_jack_cond *adc_conditions;
+
+        unsigned long irq_flags;
+        unsigned long handling_delay_ms; /* in ms */
+};
+
+#endif /* _EXTCON_ADC_JACK_H */