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Diffstat (limited to 'Documentation/iio')
| -rw-r--r-- | Documentation/iio/bno055.rst | 51 | ||||
| -rw-r--r-- | Documentation/iio/ep93xx_adc.rst | 40 | ||||
| -rw-r--r-- | Documentation/iio/iio_configfs.rst | 102 | ||||
| -rw-r--r-- | Documentation/iio/index.rst | 14 |
4 files changed, 207 insertions, 0 deletions
diff --git a/Documentation/iio/bno055.rst b/Documentation/iio/bno055.rst new file mode 100644 index 000000000..9a489a79d --- /dev/null +++ b/Documentation/iio/bno055.rst @@ -0,0 +1,51 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================== +BNO055 driver +============================== + +1. Overview +=========== + +This driver supports Bosch BNO055 IMUs (on both serial and I2C busses). + +Accelerometer, magnetometer and gyroscope measures are always provided. +When "fusion_enable" sysfs attribute is set to 1, orientation (both Euler +angles and quaternion), linear velocity and gravity vector are also +provided, but some sensor settings (e.g. low pass filtering and range) +became locked (the IMU firmware controls them). + +This driver supports also IIO buffers. + +2. Calibration +============== + +The IMU continuously performs an autocalibration procedure if (and only if) +operating in fusion mode. The magnetometer autocalibration can however be +disabled writing 0 in the sysfs in_magn_calibration_fast_enable attribute. + +The driver provides access to autocalibration flags (i.e. you can known if +the IMU has successfully autocalibrated) and to the calibration data blob. + +The user can save this blob in a firmware file (i.e. in /lib/firmware) that +the driver looks for at probe time. If found, then the IMU is initialized +with this calibration data. This saves the user from performing the +calibration procedure every time (which consist of moving the IMU in +various way). + +The driver looks for calibration data file using two different names: first +a file whose name is suffixed with the IMU unique ID (exposed in sysfs as +serial_number) is searched for; this is useful when there is more than one +IMU instance. If this file is not found, then a "generic" calibration file +is searched for (which can be used when only one IMU is present, without +struggling with fancy names, that change on each device). + +Valid calibration file names would be e.g. + bno055-caldata-0e7c26a33541515120204a35342b04ff.dat + bno055-caldata.dat + +In non-fusion mode the IIO 'offset' attributes provide access to the +offsets from calibration data (if any), so that the user can apply them to +the accel, angvel and magn IIO attributes. In fusion mode they are not +needed (the IMU firmware internally applies those corrections) and they +read as zero. diff --git a/Documentation/iio/ep93xx_adc.rst b/Documentation/iio/ep93xx_adc.rst new file mode 100644 index 000000000..0af0e9040 --- /dev/null +++ b/Documentation/iio/ep93xx_adc.rst @@ -0,0 +1,40 @@ +============================== +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 EP9315 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.rst b/Documentation/iio/iio_configfs.rst new file mode 100644 index 000000000..b276397af --- /dev/null +++ b/Documentation/iio/iio_configfs.rst @@ -0,0 +1,102 @@ +=============================== +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.rst 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_sample_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. +That attribute sets the polling frequency in Hz, with mHz precision. diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst new file mode 100644 index 000000000..1b7292c58 --- /dev/null +++ b/Documentation/iio/index.rst @@ -0,0 +1,14 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============== +Industrial I/O +============== + +.. toctree:: + :maxdepth: 1 + + iio_configfs + + ep93xx_adc + + bno055 |