1*4882a593Smuzhiyun======== 2*4882a593SmuzhiyunTriggers 3*4882a593Smuzhiyun======== 4*4882a593Smuzhiyun 5*4882a593Smuzhiyun* struct iio_trigger — industrial I/O trigger device 6*4882a593Smuzhiyun* :c:func:`devm_iio_trigger_alloc` — Resource-managed iio_trigger_alloc 7*4882a593Smuzhiyun* :c:func:`devm_iio_trigger_register` — Resource-managed iio_trigger_register 8*4882a593Smuzhiyun iio_trigger_unregister 9*4882a593Smuzhiyun* :c:func:`iio_trigger_validate_own_device` — Check if a trigger and IIO 10*4882a593Smuzhiyun device belong to the same device 11*4882a593Smuzhiyun 12*4882a593SmuzhiyunIn many situations it is useful for a driver to be able to capture data based 13*4882a593Smuzhiyunon some external event (trigger) as opposed to periodically polling for data. 14*4882a593SmuzhiyunAn IIO trigger can be provided by a device driver that also has an IIO device 15*4882a593Smuzhiyunbased on hardware generated events (e.g. data ready or threshold exceeded) or 16*4882a593Smuzhiyunprovided by a separate driver from an independent interrupt source (e.g. GPIO 17*4882a593Smuzhiyunline connected to some external system, timer interrupt or user space writing 18*4882a593Smuzhiyuna specific file in sysfs). A trigger may initiate data capture for a number of 19*4882a593Smuzhiyunsensors and also it may be completely unrelated to the sensor itself. 20*4882a593Smuzhiyun 21*4882a593SmuzhiyunIIO trigger sysfs interface 22*4882a593Smuzhiyun=========================== 23*4882a593Smuzhiyun 24*4882a593SmuzhiyunThere are two locations in sysfs related to triggers: 25*4882a593Smuzhiyun 26*4882a593Smuzhiyun* :file:`/sys/bus/iio/devices/trigger{Y}/*`, this file is created once an 27*4882a593Smuzhiyun IIO trigger is registered with the IIO core and corresponds to trigger 28*4882a593Smuzhiyun with index Y. 29*4882a593Smuzhiyun Because triggers can be very different depending on type there are few 30*4882a593Smuzhiyun standard attributes that we can describe here: 31*4882a593Smuzhiyun 32*4882a593Smuzhiyun * :file:`name`, trigger name that can be later used for association with a 33*4882a593Smuzhiyun device. 34*4882a593Smuzhiyun * :file:`sampling_frequency`, some timer based triggers use this attribute to 35*4882a593Smuzhiyun specify the frequency for trigger calls. 36*4882a593Smuzhiyun 37*4882a593Smuzhiyun* :file:`/sys/bus/iio/devices/iio:device{X}/trigger/*`, this directory is 38*4882a593Smuzhiyun created once the device supports a triggered buffer. We can associate a 39*4882a593Smuzhiyun trigger with our device by writing the trigger's name in the 40*4882a593Smuzhiyun :file:`current_trigger` file. 41*4882a593Smuzhiyun 42*4882a593SmuzhiyunIIO trigger setup 43*4882a593Smuzhiyun================= 44*4882a593Smuzhiyun 45*4882a593SmuzhiyunLet's see a simple example of how to setup a trigger to be used by a driver:: 46*4882a593Smuzhiyun 47*4882a593Smuzhiyun struct iio_trigger_ops trigger_ops = { 48*4882a593Smuzhiyun .set_trigger_state = sample_trigger_state, 49*4882a593Smuzhiyun .validate_device = sample_validate_device, 50*4882a593Smuzhiyun } 51*4882a593Smuzhiyun 52*4882a593Smuzhiyun struct iio_trigger *trig; 53*4882a593Smuzhiyun 54*4882a593Smuzhiyun /* first, allocate memory for our trigger */ 55*4882a593Smuzhiyun trig = iio_trigger_alloc(dev, "trig-%s-%d", name, idx); 56*4882a593Smuzhiyun 57*4882a593Smuzhiyun /* setup trigger operations field */ 58*4882a593Smuzhiyun trig->ops = &trigger_ops; 59*4882a593Smuzhiyun 60*4882a593Smuzhiyun /* now register the trigger with the IIO core */ 61*4882a593Smuzhiyun iio_trigger_register(trig); 62*4882a593Smuzhiyun 63*4882a593SmuzhiyunIIO trigger ops 64*4882a593Smuzhiyun=============== 65*4882a593Smuzhiyun 66*4882a593Smuzhiyun* struct iio_trigger_ops — operations structure for an iio_trigger. 67*4882a593Smuzhiyun 68*4882a593SmuzhiyunNotice that a trigger has a set of operations attached: 69*4882a593Smuzhiyun 70*4882a593Smuzhiyun* :file:`set_trigger_state`, switch the trigger on/off on demand. 71*4882a593Smuzhiyun* :file:`validate_device`, function to validate the device when the current 72*4882a593Smuzhiyun trigger gets changed. 73*4882a593Smuzhiyun 74*4882a593SmuzhiyunMore details 75*4882a593Smuzhiyun============ 76*4882a593Smuzhiyun.. kernel-doc:: include/linux/iio/trigger.h 77*4882a593Smuzhiyun.. kernel-doc:: drivers/iio/industrialio-trigger.c 78*4882a593Smuzhiyun :export: 79