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>

1 files changed, 71 insertions, 0 deletions

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 */