-Cirrus Logic EP93xx ADC driver.
+==============================
+Cirrus Logic EP93xx ADC driver
+==============================
1. Overview
+===========
The driver is intended to work on both low-end (EP9301, EP9302) devices with
5-channel ADC and high-end (EP9307, EP9312, EP9315) devices with 10-channel
touchscreen/ADC module.
2. Channel numbering
+====================
Numbering scheme for channels 0..4 is defined in EP9301 and EP9302 datasheets.
EP9307, EP9312 and EP9312 have 3 channels more (total 8), but the numbering is
+-----------------+---------------+
| sysfs entry | ball/pin name |
- +-----------------+---------------+
+ +=================+===============+
| in_voltage0_raw | YM |
+ +-----------------+---------------+
| in_voltage1_raw | SXP |
+ +-----------------+---------------+
| in_voltage2_raw | SXM |
+ +-----------------+---------------+
| in_voltage3_raw | SYP |
+ +-----------------+---------------+
| in_voltage4_raw | SYM |
+ +-----------------+---------------+
| in_voltage5_raw | XP |
+ +-----------------+---------------+
| in_voltage6_raw | XM |
+ +-----------------+---------------+
| in_voltage7_raw | YP |
+-----------------+---------------+
+===============================
Industrial IIO configfs support
+===============================
1. Overview
+===========
Configfs is a filesystem-based manager of kernel objects. IIO uses some
objects that could be easily configured using configfs (e.g.: devices,
about how configfs works.
2. Usage
+========
In order to use configfs support in IIO we need to select it at compile
time via CONFIG_IIO_CONFIGFS config option.
-Then, mount the configfs filesystem (usually under /config directory):
+Then, mount the configfs filesystem (usually under /config directory)::
-$ mkdir /config
-$ mount -t configfs none /config
+ $ mkdir /config
+ $ mount -t configfs none /config
At this point, all default IIO groups will be created and can be accessed
under /config/iio. Next chapters will describe available IIO configuration
objects.
3. Software triggers
+====================
One of the IIO default configfs groups is the "triggers" group. It is
automagically accessible when the configfs is mounted and can be found
IIO software triggers implementation offers support for creating multiple
trigger types. A new trigger type is usually implemented as a separate
-kernel module following the interface in include/linux/iio/sw_trigger.h:
+kernel module following the interface in include/linux/iio/sw_trigger.h::
-/*
- * drivers/iio/trigger/iio-trig-sample.c
- * sample kernel module implementing a new trigger type
- */
-#include <linux/iio/sw_trigger.h>
+ /*
+ * drivers/iio/trigger/iio-trig-sample.c
+ * sample kernel module implementing a new trigger type
+ */
+ #include <linux/iio/sw_trigger.h>
-static struct iio_sw_trigger *iio_trig_sample_probe(const char *name)
-{
+ static struct iio_sw_trigger *iio_trig_sample_probe(const char *name)
+ {
/*
* This allocates and registers an IIO trigger plus other
* trigger type specific initialization.
*/
-}
+ }
-static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
-{
+ static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
+ {
/*
* This undoes the actions in iio_trig_sample_probe
*/
-}
+ }
-static const struct iio_sw_trigger_ops iio_trig_sample_ops = {
+ static const struct iio_sw_trigger_ops iio_trig_sample_ops = {
.probe = iio_trig_sample_probe,
.remove = iio_trig_sample_remove,
-};
+ };
-static struct iio_sw_trigger_type iio_trig_sample = {
+ static struct iio_sw_trigger_type iio_trig_sample = {
.name = "trig-sample",
.owner = THIS_MODULE,
.ops = &iio_trig_sample_ops,
-};
+ };
module_iio_sw_trigger_driver(iio_trig_sample);
/config/iio/triggers/trig-sample.
We support the following interrupt sources (trigger types):
+
* hrtimer, uses high resolution timers as interrupt source
3.1 Hrtimer triggers creation and destruction
+---------------------------------------------
Loading iio-trig-hrtimer module will register hrtimer trigger types allowing
users to create hrtimer triggers under /config/iio/triggers/hrtimer.
-e.g:
+e.g::
-$ mkdir /config/iio/triggers/hrtimer/instance1
-$ rmdir /config/iio/triggers/hrtimer/instance1
+ $ mkdir /config/iio/triggers/hrtimer/instance1
+ $ rmdir /config/iio/triggers/hrtimer/instance1
Each trigger can have one or more attributes specific to the trigger type.
3.2 "hrtimer" trigger types attributes
+--------------------------------------
"hrtimer" trigger type doesn't have any configurable attribute from /config dir.
It does introduce the sampling_frequency attribute to trigger directory.