1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Generic sigma delta modulator driver
4 *
5 * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
6 * Author: Arnaud Pouliquen <arnaud.pouliquen@st.com>.
7 */
8
9 #include <linux/iio/backend.h>
10 #include <linux/iio/iio.h>
11 #include <linux/iio/triggered_buffer.h>
12 #include <linux/module.h>
13 #include <linux/mod_devicetable.h>
14 #include <linux/platform_device.h>
15 #include <linux/property.h>
16 #include <linux/regulator/consumer.h>
17
18 static const struct iio_info iio_sd_mod_iio_info;
19
20 static const struct iio_chan_spec iio_sd_mod_ch = {
21 .type = IIO_VOLTAGE,
22 .indexed = 1,
23 .scan_type = {
24 .sign = 'u',
25 .realbits = 1,
26 .shift = 0,
27 },
28 };
29
30 struct iio_sd_backend_priv {
31 struct regulator *vref;
32 int vref_mv;
33 };
34
iio_sd_mod_enable(struct iio_backend * backend)35 static int iio_sd_mod_enable(struct iio_backend *backend)
36 {
37 struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);
38
39 if (priv->vref)
40 return regulator_enable(priv->vref);
41
42 return 0;
43 };
44
iio_sd_mod_disable(struct iio_backend * backend)45 static void iio_sd_mod_disable(struct iio_backend *backend)
46 {
47 struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);
48
49 if (priv->vref)
50 regulator_disable(priv->vref);
51 };
52
iio_sd_mod_read(struct iio_backend * backend,struct iio_chan_spec const * chan,int * val,int * val2,long mask)53 static int iio_sd_mod_read(struct iio_backend *backend, struct iio_chan_spec const *chan, int *val,
54 int *val2, long mask)
55 {
56 struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);
57
58 switch (mask) {
59 case IIO_CHAN_INFO_SCALE:
60 *val = priv->vref_mv;
61 return IIO_VAL_INT;
62
63 case IIO_CHAN_INFO_OFFSET:
64 *val = 0;
65 return IIO_VAL_INT;
66 }
67
68 return -EOPNOTSUPP;
69 };
70
71 static const struct iio_backend_ops sd_backend_ops = {
72 .enable = iio_sd_mod_enable,
73 .disable = iio_sd_mod_disable,
74 .read_raw = iio_sd_mod_read,
75 };
76
77 static const struct iio_backend_info sd_backend_info = {
78 .name = "sd-modulator",
79 .ops = &sd_backend_ops,
80 };
81
iio_sd_mod_register(struct platform_device * pdev)82 static int iio_sd_mod_register(struct platform_device *pdev)
83 {
84 struct device *dev = &pdev->dev;
85 struct iio_dev *iio;
86
87 iio = devm_iio_device_alloc(dev, 0);
88 if (!iio)
89 return -ENOMEM;
90
91 iio->name = dev_name(dev);
92 iio->info = &iio_sd_mod_iio_info;
93 iio->modes = INDIO_BUFFER_HARDWARE;
94
95 iio->num_channels = 1;
96 iio->channels = &iio_sd_mod_ch;
97
98 platform_set_drvdata(pdev, iio);
99
100 return devm_iio_device_register(&pdev->dev, iio);
101 }
102
iio_sd_mod_probe(struct platform_device * pdev)103 static int iio_sd_mod_probe(struct platform_device *pdev)
104 {
105 struct device *dev = &pdev->dev;
106 struct regulator *vref;
107 struct iio_sd_backend_priv *priv;
108 int ret;
109
110 /* If sd modulator is not defined as an IIO backend device, fallback to legacy */
111 if (!device_property_present(dev, "#io-backend-cells"))
112 return iio_sd_mod_register(pdev);
113
114 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
115 if (!priv)
116 return -ENOMEM;
117
118 /*
119 * Get regulator reference if any, but don't enable regulator right now.
120 * Rely on enable and disable callbacks to manage regulator power.
121 */
122 vref = devm_regulator_get_optional(dev, "vref");
123 if (IS_ERR(vref)) {
124 if (PTR_ERR(vref) != -ENODEV)
125 return dev_err_probe(dev, PTR_ERR(vref), "Failed to get vref\n");
126 } else {
127 /*
128 * Retrieve voltage right now, as regulator_get_voltage() provides it whatever
129 * the state of the regulator.
130 */
131 ret = regulator_get_voltage(vref);
132 if (ret < 0)
133 return ret;
134
135 priv->vref = vref;
136 priv->vref_mv = ret / 1000;
137 }
138
139 return devm_iio_backend_register(&pdev->dev, &sd_backend_info, priv);
140 };
141
142 static const struct of_device_id sd_adc_of_match[] = {
143 { .compatible = "sd-modulator" },
144 { .compatible = "ads1201" },
145 { }
146 };
147 MODULE_DEVICE_TABLE(of, sd_adc_of_match);
148
149 static struct platform_driver iio_sd_mod_adc = {
150 .driver = {
151 .name = "iio_sd_adc_mod",
152 .of_match_table = sd_adc_of_match,
153 },
154 .probe = iio_sd_mod_probe,
155 };
156
157 module_platform_driver(iio_sd_mod_adc);
158
159 MODULE_DESCRIPTION("Basic sigma delta modulator");
160 MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>");
161 MODULE_LICENSE("GPL v2");
162 MODULE_IMPORT_NS(IIO_BACKEND);
163