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| -rw-r--r-- | Documentation/iio/ep93xx_adc.txt | 29 | ||||
| -rw-r--r-- | Documentation/iio/iio_configfs.txt | 93 |
2 files changed, 122 insertions, 0 deletions
diff --git a/Documentation/iio/ep93xx_adc.txt b/Documentation/iio/ep93xx_adc.txt new file mode 100644 index 000000000..23053e781 --- /dev/null +++ b/Documentation/iio/ep93xx_adc.txt @@ -0,0 +1,29 @@ +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 +not defined. So the last three are numbered randomly, let's say. + +Assuming ep93xx_adc is IIO device0, you'd find the following entries under +/sys/bus/iio/devices/iio:device0/: + + +-----------------+---------------+ + | 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 | + +-----------------+---------------+ diff --git a/Documentation/iio/iio_configfs.txt b/Documentation/iio/iio_configfs.txt new file mode 100644 index 000000000..4e5f10183 --- /dev/null +++ b/Documentation/iio/iio_configfs.txt @@ -0,0 +1,93 @@ +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, +triggers). + +See Documentation/filesystems/configfs/configfs.txt for more information +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): + +$ 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 +under /config/iio/triggers. + +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: + +/* + * 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) +{ + /* + * This allocates and registers an IIO trigger plus other + * trigger type specific initialization. + */ +} + +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 = { + .probe = iio_trig_sample_probe, + .remove = iio_trig_sample_remove, +}; + +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); + +Each trigger type has its own directory under /config/iio/triggers. Loading +iio-trig-sample module will create 'trig-sample' trigger type directory +/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: + +$ 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. |