1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright 2016 Jonathan Cameron <jic23@kernel.org> |
4 | * |
5 | * Based on a mashup of the hrtimer trigger and continuous sampling proposal of |
6 | * Gregor Boirie <gregor.boirie@parrot.com> |
7 | * |
8 | * Note this is still rather experimental and may eat babies. |
9 | * |
10 | * Todo |
11 | * * Protect against connection of devices that 'need' the top half |
12 | * handler. |
13 | * * Work out how to run top half handlers in this context if it is |
14 | * safe to do so (timestamp grabbing for example) |
15 | * |
16 | * Tested against a max1363. Used about 33% cpu for the thread and 20% |
17 | * for generic_buffer piping to /dev/null. Watermark set at 64 on a 128 |
18 | * element kfifo buffer. |
19 | */ |
20 | |
21 | #include <linux/kernel.h> |
22 | #include <linux/module.h> |
23 | #include <linux/platform_device.h> |
24 | #include <linux/slab.h> |
25 | #include <linux/irq_work.h> |
26 | #include <linux/kthread.h> |
27 | #include <linux/freezer.h> |
28 | |
29 | #include <linux/iio/iio.h> |
30 | #include <linux/iio/trigger.h> |
31 | #include <linux/iio/sw_trigger.h> |
32 | |
33 | struct iio_loop_info { |
34 | struct iio_sw_trigger swt; |
35 | struct task_struct *task; |
36 | }; |
37 | |
38 | static const struct config_item_type iio_loop_type = { |
39 | .ct_owner = THIS_MODULE, |
40 | }; |
41 | |
42 | static int iio_loop_thread(void *data) |
43 | { |
44 | struct iio_trigger *trig = data; |
45 | |
46 | set_freezable(); |
47 | |
48 | do { |
49 | iio_trigger_poll_nested(trig); |
50 | } while (likely(!kthread_freezable_should_stop(NULL))); |
51 | |
52 | return 0; |
53 | } |
54 | |
55 | static int iio_loop_trigger_set_state(struct iio_trigger *trig, bool state) |
56 | { |
57 | struct iio_loop_info *loop_trig = iio_trigger_get_drvdata(trig); |
58 | |
59 | if (state) { |
60 | loop_trig->task = kthread_run(iio_loop_thread, |
61 | trig, trig->name); |
62 | if (IS_ERR(ptr: loop_trig->task)) { |
63 | dev_err(&trig->dev, |
64 | "failed to create trigger loop thread\n" ); |
65 | return PTR_ERR(ptr: loop_trig->task); |
66 | } |
67 | } else { |
68 | kthread_stop(k: loop_trig->task); |
69 | } |
70 | |
71 | return 0; |
72 | } |
73 | |
74 | static const struct iio_trigger_ops iio_loop_trigger_ops = { |
75 | .set_trigger_state = iio_loop_trigger_set_state, |
76 | }; |
77 | |
78 | static struct iio_sw_trigger *iio_trig_loop_probe(const char *name) |
79 | { |
80 | struct iio_loop_info *trig_info; |
81 | int ret; |
82 | |
83 | trig_info = kzalloc(size: sizeof(*trig_info), GFP_KERNEL); |
84 | if (!trig_info) |
85 | return ERR_PTR(error: -ENOMEM); |
86 | |
87 | trig_info->swt.trigger = iio_trigger_alloc(NULL, "%s" , name); |
88 | if (!trig_info->swt.trigger) { |
89 | ret = -ENOMEM; |
90 | goto err_free_trig_info; |
91 | } |
92 | |
93 | iio_trigger_set_drvdata(trig: trig_info->swt.trigger, data: trig_info); |
94 | trig_info->swt.trigger->ops = &iio_loop_trigger_ops; |
95 | |
96 | ret = iio_trigger_register(trig_info: trig_info->swt.trigger); |
97 | if (ret) |
98 | goto err_free_trigger; |
99 | |
100 | iio_swt_group_init_type_name(t: &trig_info->swt, name, type: &iio_loop_type); |
101 | |
102 | return &trig_info->swt; |
103 | |
104 | err_free_trigger: |
105 | iio_trigger_free(trig: trig_info->swt.trigger); |
106 | err_free_trig_info: |
107 | kfree(objp: trig_info); |
108 | |
109 | return ERR_PTR(error: ret); |
110 | } |
111 | |
112 | static int iio_trig_loop_remove(struct iio_sw_trigger *swt) |
113 | { |
114 | struct iio_loop_info *trig_info; |
115 | |
116 | trig_info = iio_trigger_get_drvdata(trig: swt->trigger); |
117 | |
118 | iio_trigger_unregister(trig_info: swt->trigger); |
119 | iio_trigger_free(trig: swt->trigger); |
120 | kfree(objp: trig_info); |
121 | |
122 | return 0; |
123 | } |
124 | |
125 | static const struct iio_sw_trigger_ops iio_trig_loop_ops = { |
126 | .probe = iio_trig_loop_probe, |
127 | .remove = iio_trig_loop_remove, |
128 | }; |
129 | |
130 | static struct iio_sw_trigger_type iio_trig_loop = { |
131 | .name = "loop" , |
132 | .owner = THIS_MODULE, |
133 | .ops = &iio_trig_loop_ops, |
134 | }; |
135 | |
136 | module_iio_sw_trigger_driver(iio_trig_loop); |
137 | |
138 | MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>" ); |
139 | MODULE_DESCRIPTION("Loop based trigger for the iio subsystem" ); |
140 | MODULE_LICENSE("GPL v2" ); |
141 | MODULE_ALIAS("platform:iio-trig-loop" ); |
142 | |