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bc2e1126 JC |
1 | /* |
2 | * Copyright 2016 Jonathan Cameron <jic23@kernel.org> | |
3 | * | |
4 | * Licensed under the GPL-2. | |
5 | * | |
6 | * Based on a mashup of the hrtimer trigger and continuous sampling proposal of | |
7 | * Gregor Boirie <gregor.boirie@parrot.com> | |
8 | * | |
9 | * Note this is still rather experimental and may eat babies. | |
10 | * | |
11 | * Todo | |
12 | * * Protect against connection of devices that 'need' the top half | |
13 | * handler. | |
14 | * * Work out how to run top half handlers in this context if it is | |
15 | * safe to do so (timestamp grabbing for example) | |
16 | * | |
17 | * Tested against a max1363. Used about 33% cpu for the thread and 20% | |
18 | * for generic_buffer piping to /dev/null. Watermark set at 64 on a 128 | |
19 | * element kfifo buffer. | |
20 | */ | |
21 | ||
22 | #include <linux/kernel.h> | |
23 | #include <linux/module.h> | |
24 | #include <linux/platform_device.h> | |
25 | #include <linux/slab.h> | |
26 | #include <linux/irq_work.h> | |
27 | #include <linux/kthread.h> | |
28 | #include <linux/freezer.h> | |
29 | ||
30 | #include <linux/iio/iio.h> | |
31 | #include <linux/iio/trigger.h> | |
32 | #include <linux/iio/sw_trigger.h> | |
33 | ||
34 | struct iio_loop_info { | |
35 | struct iio_sw_trigger swt; | |
36 | struct task_struct *task; | |
37 | }; | |
38 | ||
612a462a | 39 | static const struct config_item_type iio_loop_type = { |
bc2e1126 JC |
40 | .ct_owner = THIS_MODULE, |
41 | }; | |
42 | ||
43 | static int iio_loop_thread(void *data) | |
44 | { | |
45 | struct iio_trigger *trig = data; | |
46 | ||
47 | set_freezable(); | |
48 | ||
49 | do { | |
50 | iio_trigger_poll_chained(trig); | |
51 | } while (likely(!kthread_freezable_should_stop(NULL))); | |
52 | ||
53 | return 0; | |
54 | } | |
55 | ||
56 | static int iio_loop_trigger_set_state(struct iio_trigger *trig, bool state) | |
57 | { | |
58 | struct iio_loop_info *loop_trig = iio_trigger_get_drvdata(trig); | |
59 | ||
60 | if (state) { | |
61 | loop_trig->task = kthread_run(iio_loop_thread, | |
62 | trig, trig->name); | |
63 | if (unlikely(IS_ERR(loop_trig->task))) { | |
64 | dev_err(&trig->dev, | |
65 | "failed to create trigger loop thread\n"); | |
66 | return PTR_ERR(loop_trig->task); | |
67 | } | |
68 | } else { | |
69 | kthread_stop(loop_trig->task); | |
70 | } | |
71 | ||
72 | return 0; | |
73 | } | |
74 | ||
75 | static const struct iio_trigger_ops iio_loop_trigger_ops = { | |
76 | .set_trigger_state = iio_loop_trigger_set_state, | |
bc2e1126 JC |
77 | }; |
78 | ||
79 | static struct iio_sw_trigger *iio_trig_loop_probe(const char *name) | |
80 | { | |
81 | struct iio_loop_info *trig_info; | |
82 | int ret; | |
83 | ||
84 | trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL); | |
85 | if (!trig_info) | |
86 | return ERR_PTR(-ENOMEM); | |
87 | ||
88 | trig_info->swt.trigger = iio_trigger_alloc("%s", name); | |
89 | if (!trig_info->swt.trigger) { | |
90 | ret = -ENOMEM; | |
91 | goto err_free_trig_info; | |
92 | } | |
93 | ||
94 | iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info); | |
95 | trig_info->swt.trigger->ops = &iio_loop_trigger_ops; | |
96 | ||
97 | ret = iio_trigger_register(trig_info->swt.trigger); | |
98 | if (ret) | |
99 | goto err_free_trigger; | |
100 | ||
101 | iio_swt_group_init_type_name(&trig_info->swt, name, &iio_loop_type); | |
102 | ||
103 | return &trig_info->swt; | |
104 | ||
105 | err_free_trigger: | |
106 | iio_trigger_free(trig_info->swt.trigger); | |
107 | err_free_trig_info: | |
108 | kfree(trig_info); | |
109 | ||
110 | return ERR_PTR(ret); | |
111 | } | |
112 | ||
113 | static int iio_trig_loop_remove(struct iio_sw_trigger *swt) | |
114 | { | |
115 | struct iio_loop_info *trig_info; | |
116 | ||
117 | trig_info = iio_trigger_get_drvdata(swt->trigger); | |
118 | ||
119 | iio_trigger_unregister(swt->trigger); | |
120 | iio_trigger_free(swt->trigger); | |
121 | kfree(trig_info); | |
122 | ||
123 | return 0; | |
124 | } | |
125 | ||
126 | static const struct iio_sw_trigger_ops iio_trig_loop_ops = { | |
127 | .probe = iio_trig_loop_probe, | |
128 | .remove = iio_trig_loop_remove, | |
129 | }; | |
130 | ||
131 | static struct iio_sw_trigger_type iio_trig_loop = { | |
132 | .name = "loop", | |
133 | .owner = THIS_MODULE, | |
134 | .ops = &iio_trig_loop_ops, | |
135 | }; | |
136 | ||
137 | module_iio_sw_trigger_driver(iio_trig_loop); | |
138 | ||
139 | MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>"); | |
140 | MODULE_DESCRIPTION("Loop based trigger for the iio subsystem"); | |
141 | MODULE_LICENSE("GPL v2"); | |
142 | MODULE_ALIAS("platform:iio-trig-loop"); |