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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * iio/adc/max11100.c
4 * Maxim max11100 ADC Driver with IIO interface
5 *
6 * Copyright (C) 2016-17 Renesas Electronics Corporation
7 * Copyright (C) 2016-17 Jacopo Mondi
8 */
9#include <linux/delay.h>
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/regulator/consumer.h>
13#include <linux/spi/spi.h>
14
15#include <linux/iio/iio.h>
16#include <linux/iio/driver.h>
17
18/*
19 * LSB is the ADC single digital step
20 * 1 LSB = (vref_mv / 2 ^ 16)
21 *
22 * LSB is used to calculate analog voltage value
23 * from the number of ADC steps count
24 *
25 * Ain = (count * LSB)
26 */
27#define MAX11100_LSB_DIV (1 << 16)
28
29struct max11100_state {
30 struct regulator *vref_reg;
31 struct spi_device *spi;
32
33 /*
34 * DMA (thus cache coherency maintenance) requires the
35 * transfer buffers to live in their own cache lines.
36 */
37 u8 buffer[3] ____cacheline_aligned;
38};
39
40static struct iio_chan_spec max11100_channels[] = {
41 { /* [0] */
42 .type = IIO_VOLTAGE,
43 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
44 BIT(IIO_CHAN_INFO_SCALE),
45 },
46};
47
48static int max11100_read_single(struct iio_dev *indio_dev, int *val)
49{
50 int ret;
51 struct max11100_state *state = iio_priv(indio_dev);
52
53 ret = spi_read(state->spi, state->buffer, sizeof(state->buffer));
54 if (ret) {
55 dev_err(&indio_dev->dev, "SPI transfer failed\n");
56 return ret;
57 }
58
59 /* the first 8 bits sent out from ADC must be 0s */
60 if (state->buffer[0]) {
61 dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n");
62 return -EINVAL;
63 }
64
65 *val = (state->buffer[1] << 8) | state->buffer[2];
66
67 return 0;
68}
69
70static int max11100_read_raw(struct iio_dev *indio_dev,
71 struct iio_chan_spec const *chan,
72 int *val, int *val2, long info)
73{
74 int ret, vref_uv;
75 struct max11100_state *state = iio_priv(indio_dev);
76
77 switch (info) {
78 case IIO_CHAN_INFO_RAW:
79 ret = max11100_read_single(indio_dev, val);
80 if (ret)
81 return ret;
82
83 return IIO_VAL_INT;
84
85 case IIO_CHAN_INFO_SCALE:
86 vref_uv = regulator_get_voltage(state->vref_reg);
87 if (vref_uv < 0)
88 /* dummy regulator "get_voltage" returns -EINVAL */
89 return -EINVAL;
90
91 *val = vref_uv / 1000;
92 *val2 = MAX11100_LSB_DIV;
93 return IIO_VAL_FRACTIONAL;
94 }
95
96 return -EINVAL;
97}
98
99static const struct iio_info max11100_info = {
100 .read_raw = max11100_read_raw,
101};
102
103static int max11100_probe(struct spi_device *spi)
104{
105 int ret;
106 struct iio_dev *indio_dev;
107 struct max11100_state *state;
108
109 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
110 if (!indio_dev)
111 return -ENOMEM;
112
113 spi_set_drvdata(spi, indio_dev);
114
115 state = iio_priv(indio_dev);
116 state->spi = spi;
117
118 indio_dev->dev.parent = &spi->dev;
119 indio_dev->dev.of_node = spi->dev.of_node;
120 indio_dev->name = "max11100";
121 indio_dev->info = &max11100_info;
122 indio_dev->modes = INDIO_DIRECT_MODE;
123 indio_dev->channels = max11100_channels;
124 indio_dev->num_channels = ARRAY_SIZE(max11100_channels);
125
126 state->vref_reg = devm_regulator_get(&spi->dev, "vref");
127 if (IS_ERR(state->vref_reg))
128 return PTR_ERR(state->vref_reg);
129
130 ret = regulator_enable(state->vref_reg);
131 if (ret)
132 return ret;
133
134 ret = iio_device_register(indio_dev);
135 if (ret)
136 goto disable_regulator;
137
138 return 0;
139
140disable_regulator:
141 regulator_disable(state->vref_reg);
142
143 return ret;
144}
145
146static int max11100_remove(struct spi_device *spi)
147{
148 struct iio_dev *indio_dev = spi_get_drvdata(spi);
149 struct max11100_state *state = iio_priv(indio_dev);
150
151 iio_device_unregister(indio_dev);
152 regulator_disable(state->vref_reg);
153
154 return 0;
155}
156
157static const struct of_device_id max11100_ids[] = {
158 {.compatible = "maxim,max11100"},
159 { },
160};
161MODULE_DEVICE_TABLE(of, max11100_ids);
162
163static struct spi_driver max11100_driver = {
164 .driver = {
165 .name = "max11100",
166 .of_match_table = of_match_ptr(max11100_ids),
167 },
168 .probe = max11100_probe,
169 .remove = max11100_remove,
170};
171
172module_spi_driver(max11100_driver);
173
174MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
175MODULE_DESCRIPTION("Maxim max11100 ADC Driver");
176MODULE_LICENSE("GPL v2");
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * iio/adc/max11100.c
4 * Maxim max11100 ADC Driver with IIO interface
5 *
6 * Copyright (C) 2016-17 Renesas Electronics Corporation
7 * Copyright (C) 2016-17 Jacopo Mondi
8 */
9#include <linux/delay.h>
10#include <linux/kernel.h>
11#include <linux/mod_devicetable.h>
12#include <linux/module.h>
13#include <linux/regulator/consumer.h>
14#include <linux/spi/spi.h>
15
16#include <linux/iio/iio.h>
17#include <linux/iio/driver.h>
18
19/*
20 * LSB is the ADC single digital step
21 * 1 LSB = (vref_mv / 2 ^ 16)
22 *
23 * LSB is used to calculate analog voltage value
24 * from the number of ADC steps count
25 *
26 * Ain = (count * LSB)
27 */
28#define MAX11100_LSB_DIV (1 << 16)
29
30struct max11100_state {
31 struct regulator *vref_reg;
32 struct spi_device *spi;
33
34 /*
35 * DMA (thus cache coherency maintenance) requires the
36 * transfer buffers to live in their own cache lines.
37 */
38 u8 buffer[3] ____cacheline_aligned;
39};
40
41static const struct iio_chan_spec max11100_channels[] = {
42 { /* [0] */
43 .type = IIO_VOLTAGE,
44 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
45 BIT(IIO_CHAN_INFO_SCALE),
46 },
47};
48
49static int max11100_read_single(struct iio_dev *indio_dev, int *val)
50{
51 int ret;
52 struct max11100_state *state = iio_priv(indio_dev);
53
54 ret = spi_read(state->spi, state->buffer, sizeof(state->buffer));
55 if (ret) {
56 dev_err(&indio_dev->dev, "SPI transfer failed\n");
57 return ret;
58 }
59
60 /* the first 8 bits sent out from ADC must be 0s */
61 if (state->buffer[0]) {
62 dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n");
63 return -EINVAL;
64 }
65
66 *val = (state->buffer[1] << 8) | state->buffer[2];
67
68 return 0;
69}
70
71static int max11100_read_raw(struct iio_dev *indio_dev,
72 struct iio_chan_spec const *chan,
73 int *val, int *val2, long info)
74{
75 int ret, vref_uv;
76 struct max11100_state *state = iio_priv(indio_dev);
77
78 switch (info) {
79 case IIO_CHAN_INFO_RAW:
80 ret = max11100_read_single(indio_dev, val);
81 if (ret)
82 return ret;
83
84 return IIO_VAL_INT;
85
86 case IIO_CHAN_INFO_SCALE:
87 vref_uv = regulator_get_voltage(state->vref_reg);
88 if (vref_uv < 0)
89 /* dummy regulator "get_voltage" returns -EINVAL */
90 return -EINVAL;
91
92 *val = vref_uv / 1000;
93 *val2 = MAX11100_LSB_DIV;
94 return IIO_VAL_FRACTIONAL;
95 }
96
97 return -EINVAL;
98}
99
100static const struct iio_info max11100_info = {
101 .read_raw = max11100_read_raw,
102};
103
104static int max11100_probe(struct spi_device *spi)
105{
106 int ret;
107 struct iio_dev *indio_dev;
108 struct max11100_state *state;
109
110 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
111 if (!indio_dev)
112 return -ENOMEM;
113
114 spi_set_drvdata(spi, indio_dev);
115
116 state = iio_priv(indio_dev);
117 state->spi = spi;
118
119 indio_dev->name = "max11100";
120 indio_dev->info = &max11100_info;
121 indio_dev->modes = INDIO_DIRECT_MODE;
122 indio_dev->channels = max11100_channels;
123 indio_dev->num_channels = ARRAY_SIZE(max11100_channels);
124
125 state->vref_reg = devm_regulator_get(&spi->dev, "vref");
126 if (IS_ERR(state->vref_reg))
127 return PTR_ERR(state->vref_reg);
128
129 ret = regulator_enable(state->vref_reg);
130 if (ret)
131 return ret;
132
133 ret = iio_device_register(indio_dev);
134 if (ret)
135 goto disable_regulator;
136
137 return 0;
138
139disable_regulator:
140 regulator_disable(state->vref_reg);
141
142 return ret;
143}
144
145static int max11100_remove(struct spi_device *spi)
146{
147 struct iio_dev *indio_dev = spi_get_drvdata(spi);
148 struct max11100_state *state = iio_priv(indio_dev);
149
150 iio_device_unregister(indio_dev);
151 regulator_disable(state->vref_reg);
152
153 return 0;
154}
155
156static const struct of_device_id max11100_ids[] = {
157 {.compatible = "maxim,max11100"},
158 { },
159};
160MODULE_DEVICE_TABLE(of, max11100_ids);
161
162static struct spi_driver max11100_driver = {
163 .driver = {
164 .name = "max11100",
165 .of_match_table = max11100_ids,
166 },
167 .probe = max11100_probe,
168 .remove = max11100_remove,
169};
170
171module_spi_driver(max11100_driver);
172
173MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
174MODULE_DESCRIPTION("Maxim max11100 ADC Driver");
175MODULE_LICENSE("GPL v2");