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Subject[PATCH v5 5/5] Extcon: adc-jack driver to support 3.5 pi or simliar devices
Date
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.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
drivers/extcon/Kconfig | 7 ++-
drivers/extcon/Makefile | 1 +
drivers/extcon/adc_jack.c | 188 +++++++++++++++++++++++++++++++++++++++
include/linux/extcon/adc_jack.h | 107 ++++++++++++++++++++++
4 files changed, 302 insertions(+), 1 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 3fa3c22..7487384 100644
--- a/drivers/extcon/Kconfig
+++ b/drivers/extcon/Kconfig
@@ -19,4 +19,9 @@ config EXTCON_GPIO
Say Y here to enable GPIO based extcon support. Note that GPIO
extcon supports single state per extcon instance.

-endif # MULTISTATE_SWITCH
+config EXTCON_ADC_JACK
+ tristate "ADC Jack extcon support"
+ help
+ Say Y here to enable extcon device driver based on ADC values.
+
+endif # EXTCON
diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
index 2c46d41..ca558a0 100644
--- a/drivers/extcon/Makefile
+++ b/drivers/extcon/Makefile
@@ -4,3 +4,4 @@

obj-$(CONFIG_EXTCON) += extcon_class.o
obj-$(CONFIG_EXTCON_GPIO) += extcon_gpio.o
+obj-$(CONFIG_EXTCON_ADC_JACK) += adc_jack.o
diff --git a/drivers/extcon/adc_jack.c b/drivers/extcon/adc_jack.c
new file mode 100644
index 0000000..9cad565
--- /dev/null
+++ b/drivers/extcon/adc_jack.c
@@ -0,0 +1,188 @@
+/*
+ * 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>
+ *
+ * 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/extcon.h>
+#include <linux/extcon/adc_jack.h>
+
+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 adc, state = 0;
+ int ret;
+ int i;
+
+ if (!data->ready)
+ return;
+
+ ret = data->get_adc(&adc);
+ if (ret) {
+ dev_err(data->edev.dev, "get_adc() 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 && def->max_adc >= adc) {
+ 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 = kzalloc(sizeof(struct adc_jack_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;
+
+ if (!pdata->get_adc) {
+ dev_err(&pdev->dev, "error: get_adc() is mandatory.\n");
+ err = -EINVAL;
+ goto err_alloc;
+ }
+ data->get_adc = pdata->get_adc;
+ data->handling_delay = msecs_to_jiffies(pdata->handling_delay_ms);
+
+ INIT_DELAYED_WORK_DEFERRABLE(&data->handler, adc_jack_handler);
+
+ platform_set_drvdata(pdev, data);
+
+ if (pdata->irq) {
+ data->irq = pdata->irq;
+
+ err = request_threaded_irq(data->irq, NULL,
+ 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_initwork;
+ }
+ }
+ err = extcon_dev_register(&data->edev, &pdev->dev);
+ if (err)
+ goto err_irq;
+
+ data->ready = true;
+
+ goto out;
+
+err_irq:
+ if (data->irq)
+ free_irq(data->irq, data);
+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);
+ platform_set_drvdata(pdev, NULL);
+ kfree(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,
+ },
+};
+
+static int __init adc_jack_init(void)
+{
+ return platform_driver_register(&adc_jack_driver);
+}
+
+static void __exit adc_jack_exit(void)
+{
+ platform_driver_unregister(&adc_jack_driver);
+}
+
+module_init(adc_jack_init);
+module_exit(adc_jack_exit);
+
+MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
+MODULE_DESCRIPTION("ADC jack extcon driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/extcon/adc_jack.h b/include/linux/extcon/adc_jack.h
new file mode 100644
index 0000000..1650b85
--- /dev/null
+++ b/include/linux/extcon/adc_jack.h
@@ -0,0 +1,107 @@
+/*
+ * 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/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.
+ * @ready - true if it is safe to run handler.
+ */
+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;
+
+ int (*get_adc)(u32 *value);
+
+ bool ready;
+};
+
+/**
+ * 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;
+ /*
+ * 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;
+
+ int irq; /* Jack insertion/removal interrupt */
+ 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 */
--
1.7.4.1


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