1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * STM32 Low-Power Timer Trigger driver
4  *
5  * Copyright (C) STMicroelectronics 2017
6  *
7  * Author: Fabrice Gasnier <fabrice.gasnier@st.com>.
8  *
9  * Inspired by Benjamin Gaignard's stm32-timer-trigger driver
10  */
11 
12 #include <linux/iio/timer/stm32-lptim-trigger.h>
13 #include <linux/mfd/stm32-lptimer.h>
14 #include <linux/mod_devicetable.h>
15 #include <linux/module.h>
16 #include <linux/platform_device.h>
17 #include <linux/property.h>
18 
19 /* List Low-Power Timer triggers */
20 static const char * const stm32_lptim_triggers[] = {
21 	LPTIM1_OUT,
22 	LPTIM2_OUT,
23 	LPTIM3_OUT,
24 };
25 
26 struct stm32_lptim_trigger {
27 	struct device *dev;
28 	const char *trg;
29 };
30 
31 static int stm32_lptim_validate_device(struct iio_trigger *trig,
32 				       struct iio_dev *indio_dev)
33 {
34 	if (indio_dev->modes & INDIO_HARDWARE_TRIGGERED)
35 		return 0;
36 
37 	return -EINVAL;
38 }
39 
40 static const struct iio_trigger_ops stm32_lptim_trigger_ops = {
41 	.validate_device = stm32_lptim_validate_device,
42 };
43 
44 /**
45  * is_stm32_lptim_trigger
46  * @trig: trigger to be checked
47  *
48  * return true if the trigger is a valid STM32 IIO Low-Power Timer Trigger
49  * either return false
50  */
51 bool is_stm32_lptim_trigger(struct iio_trigger *trig)
52 {
53 	return (trig->ops == &stm32_lptim_trigger_ops);
54 }
55 EXPORT_SYMBOL(is_stm32_lptim_trigger);
56 
57 static int stm32_lptim_setup_trig(struct stm32_lptim_trigger *priv)
58 {
59 	struct iio_trigger *trig;
60 
61 	trig = devm_iio_trigger_alloc(priv->dev, "%s", priv->trg);
62 	if  (!trig)
63 		return -ENOMEM;
64 
65 	trig->dev.parent = priv->dev->parent;
66 	trig->ops = &stm32_lptim_trigger_ops;
67 	iio_trigger_set_drvdata(trig, priv);
68 
69 	return devm_iio_trigger_register(priv->dev, trig);
70 }
71 
72 static int stm32_lptim_trigger_probe(struct platform_device *pdev)
73 {
74 	struct stm32_lptim_trigger *priv;
75 	u32 index;
76 
77 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
78 	if (!priv)
79 		return -ENOMEM;
80 
81 	if (device_property_read_u32(&pdev->dev, "reg", &index))
82 		return -EINVAL;
83 
84 	if (index >= ARRAY_SIZE(stm32_lptim_triggers))
85 		return -EINVAL;
86 
87 	priv->dev = &pdev->dev;
88 	priv->trg = stm32_lptim_triggers[index];
89 
90 	return stm32_lptim_setup_trig(priv);
91 }
92 
93 static const struct of_device_id stm32_lptim_trig_of_match[] = {
94 	{ .compatible = "st,stm32-lptimer-trigger", },
95 	{},
96 };
97 MODULE_DEVICE_TABLE(of, stm32_lptim_trig_of_match);
98 
99 static struct platform_driver stm32_lptim_trigger_driver = {
100 	.probe = stm32_lptim_trigger_probe,
101 	.driver = {
102 		.name = "stm32-lptimer-trigger",
103 		.of_match_table = stm32_lptim_trig_of_match,
104 	},
105 };
106 module_platform_driver(stm32_lptim_trigger_driver);
107 
108 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
109 MODULE_ALIAS("platform:stm32-lptimer-trigger");
110 MODULE_DESCRIPTION("STMicroelectronics STM32 LPTIM trigger driver");
111 MODULE_LICENSE("GPL v2");
112