1 =============================== 1 ===============================
2 Industrial IIO configfs support 2 Industrial IIO configfs support
3 =============================== 3 ===============================
4 4
5 1. Overview 5 1. Overview
6 =========== 6 ===========
7 7
8 Configfs is a filesystem-based manager of kern 8 Configfs is a filesystem-based manager of kernel objects. IIO uses some
9 objects that could be easily configured using 9 objects that could be easily configured using configfs (e.g.: devices,
10 triggers). 10 triggers).
11 11
12 See Documentation/filesystems/configfs.rst for 12 See Documentation/filesystems/configfs.rst for more information
13 about how configfs works. 13 about how configfs works.
14 14
15 2. Usage 15 2. Usage
16 ======== 16 ========
17 17
18 In order to use configfs support in IIO we nee 18 In order to use configfs support in IIO we need to select it at compile
19 time via CONFIG_IIO_CONFIGFS config option. 19 time via CONFIG_IIO_CONFIGFS config option.
20 20
21 Then, mount the configfs filesystem (usually u 21 Then, mount the configfs filesystem (usually under /config directory)::
22 22
23 $ mkdir /config 23 $ mkdir /config
24 $ mount -t configfs none /config 24 $ mount -t configfs none /config
25 25
26 At this point, all default IIO groups will be 26 At this point, all default IIO groups will be created and can be accessed
27 under /config/iio. Next chapters will describe 27 under /config/iio. Next chapters will describe available IIO configuration
28 objects. 28 objects.
29 29
30 3. Software triggers 30 3. Software triggers
31 ==================== 31 ====================
32 32
33 One of the IIO default configfs groups is the 33 One of the IIO default configfs groups is the "triggers" group. It is
34 automagically accessible when the configfs is 34 automagically accessible when the configfs is mounted and can be found
35 under /config/iio/triggers. 35 under /config/iio/triggers.
36 36
37 IIO software triggers implementation offers su 37 IIO software triggers implementation offers support for creating multiple
38 trigger types. A new trigger type is usually i 38 trigger types. A new trigger type is usually implemented as a separate
39 kernel module following the interface in inclu 39 kernel module following the interface in include/linux/iio/sw_trigger.h::
40 40
41 /* 41 /*
42 * drivers/iio/trigger/iio-trig-sample.c 42 * drivers/iio/trigger/iio-trig-sample.c
43 * sample kernel module implementing a new t 43 * sample kernel module implementing a new trigger type
44 */ 44 */
45 #include <linux/iio/sw_trigger.h> 45 #include <linux/iio/sw_trigger.h>
46 46
47 47
48 static struct iio_sw_trigger *iio_trig_sampl 48 static struct iio_sw_trigger *iio_trig_sample_probe(const char *name)
49 { 49 {
50 /* 50 /*
51 * This allocates and registers an IIO 51 * This allocates and registers an IIO trigger plus other
52 * trigger type specific initializatio 52 * trigger type specific initialization.
53 */ 53 */
54 } 54 }
55 55
56 static int iio_trig_sample_remove(struct iio 56 static int iio_trig_sample_remove(struct iio_sw_trigger *swt)
57 { 57 {
58 /* 58 /*
59 * This undoes the actions in iio_trig 59 * This undoes the actions in iio_trig_sample_probe
60 */ 60 */
61 } 61 }
62 62
63 static const struct iio_sw_trigger_ops iio_t 63 static const struct iio_sw_trigger_ops iio_trig_sample_ops = {
64 .probe = iio_trig_sample_prob 64 .probe = iio_trig_sample_probe,
65 .remove = iio_trig_sample_remo 65 .remove = iio_trig_sample_remove,
66 }; 66 };
67 67
68 static struct iio_sw_trigger_type iio_trig_s 68 static struct iio_sw_trigger_type iio_trig_sample = {
69 .name = "trig-sample", 69 .name = "trig-sample",
70 .owner = THIS_MODULE, 70 .owner = THIS_MODULE,
71 .ops = &iio_trig_sample_ops, 71 .ops = &iio_trig_sample_ops,
72 }; 72 };
73 73
74 module_iio_sw_trigger_driver(iio_trig_sample 74 module_iio_sw_trigger_driver(iio_trig_sample);
75 75
76 Each trigger type has its own directory under 76 Each trigger type has its own directory under /config/iio/triggers. Loading
77 iio-trig-sample module will create 'trig-sampl 77 iio-trig-sample module will create 'trig-sample' trigger type directory
78 /config/iio/triggers/trig-sample. 78 /config/iio/triggers/trig-sample.
79 79
80 We support the following interrupt sources (tr 80 We support the following interrupt sources (trigger types):
81 81
82 * hrtimer, uses high resolution timers 82 * hrtimer, uses high resolution timers as interrupt source
83 83
84 3.1 Hrtimer triggers creation and destruction 84 3.1 Hrtimer triggers creation and destruction
85 --------------------------------------------- 85 ---------------------------------------------
86 86
87 Loading iio-trig-hrtimer module will register 87 Loading iio-trig-hrtimer module will register hrtimer trigger types allowing
88 users to create hrtimer triggers under /config 88 users to create hrtimer triggers under /config/iio/triggers/hrtimer.
89 89
90 e.g:: 90 e.g::
91 91
92 $ mkdir /config/iio/triggers/hrtimer/instanc 92 $ mkdir /config/iio/triggers/hrtimer/instance1
93 $ rmdir /config/iio/triggers/hrtimer/instanc 93 $ rmdir /config/iio/triggers/hrtimer/instance1
94 94
95 Each trigger can have one or more attributes s 95 Each trigger can have one or more attributes specific to the trigger type.
96 96
97 3.2 "hrtimer" trigger types attributes 97 3.2 "hrtimer" trigger types attributes
98 -------------------------------------- 98 --------------------------------------
99 99
100 "hrtimer" trigger type doesn't have any config 100 "hrtimer" trigger type doesn't have any configurable attribute from /config dir.
101 It does introduce the sampling_frequency attri 101 It does introduce the sampling_frequency attribute to trigger directory.
102 That attribute sets the polling frequency in H 102 That attribute sets the polling frequency in Hz, with mHz precision.
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