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 | #include <asm/unaligned.h> |
16 | |
17 | #include <linux/iio/iio.h> |
18 | #include <linux/iio/driver.h> |
19 | |
20 | /* |
21 | * LSB is the ADC single digital step |
22 | * 1 LSB = (vref_mv / 2 ^ 16) |
23 | * |
24 | * LSB is used to calculate analog voltage value |
25 | * from the number of ADC steps count |
26 | * |
27 | * Ain = (count * LSB) |
28 | */ |
29 | #define MAX11100_LSB_DIV (1 << 16) |
30 | |
31 | struct max11100_state { |
32 | struct regulator *vref_reg; |
33 | struct spi_device *spi; |
34 | |
35 | /* |
36 | * DMA (thus cache coherency maintenance) may require the |
37 | * transfer buffers to live in their own cache lines. |
38 | */ |
39 | u8 buffer[3] __aligned(IIO_DMA_MINALIGN); |
40 | }; |
41 | |
42 | static const struct iio_chan_spec max11100_channels[] = { |
43 | { /* [0] */ |
44 | .type = IIO_VOLTAGE, |
45 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | |
46 | BIT(IIO_CHAN_INFO_SCALE), |
47 | }, |
48 | }; |
49 | |
50 | static int max11100_read_single(struct iio_dev *indio_dev, int *val) |
51 | { |
52 | int ret; |
53 | struct max11100_state *state = iio_priv(indio_dev); |
54 | |
55 | ret = spi_read(spi: state->spi, buf: state->buffer, len: sizeof(state->buffer)); |
56 | if (ret) { |
57 | dev_err(&indio_dev->dev, "SPI transfer failed\n" ); |
58 | return ret; |
59 | } |
60 | |
61 | /* the first 8 bits sent out from ADC must be 0s */ |
62 | if (state->buffer[0]) { |
63 | dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n" ); |
64 | return -EINVAL; |
65 | } |
66 | |
67 | *val = get_unaligned_be16(p: &state->buffer[1]); |
68 | |
69 | return 0; |
70 | } |
71 | |
72 | static int max11100_read_raw(struct iio_dev *indio_dev, |
73 | struct iio_chan_spec const *chan, |
74 | int *val, int *val2, long info) |
75 | { |
76 | int ret, vref_uv; |
77 | struct max11100_state *state = iio_priv(indio_dev); |
78 | |
79 | switch (info) { |
80 | case IIO_CHAN_INFO_RAW: |
81 | ret = max11100_read_single(indio_dev, val); |
82 | if (ret) |
83 | return ret; |
84 | |
85 | return IIO_VAL_INT; |
86 | |
87 | case IIO_CHAN_INFO_SCALE: |
88 | vref_uv = regulator_get_voltage(regulator: state->vref_reg); |
89 | if (vref_uv < 0) |
90 | /* dummy regulator "get_voltage" returns -EINVAL */ |
91 | return -EINVAL; |
92 | |
93 | *val = vref_uv / 1000; |
94 | *val2 = MAX11100_LSB_DIV; |
95 | return IIO_VAL_FRACTIONAL; |
96 | } |
97 | |
98 | return -EINVAL; |
99 | } |
100 | |
101 | static const struct iio_info max11100_info = { |
102 | .read_raw = max11100_read_raw, |
103 | }; |
104 | |
105 | static void max11100_regulator_disable(void *reg) |
106 | { |
107 | regulator_disable(regulator: reg); |
108 | } |
109 | |
110 | static int max11100_probe(struct spi_device *spi) |
111 | { |
112 | int ret; |
113 | struct iio_dev *indio_dev; |
114 | struct max11100_state *state; |
115 | |
116 | indio_dev = devm_iio_device_alloc(parent: &spi->dev, sizeof_priv: sizeof(*state)); |
117 | if (!indio_dev) |
118 | return -ENOMEM; |
119 | |
120 | state = iio_priv(indio_dev); |
121 | state->spi = spi; |
122 | |
123 | indio_dev->name = "max11100" ; |
124 | indio_dev->info = &max11100_info; |
125 | indio_dev->modes = INDIO_DIRECT_MODE; |
126 | indio_dev->channels = max11100_channels; |
127 | indio_dev->num_channels = ARRAY_SIZE(max11100_channels); |
128 | |
129 | state->vref_reg = devm_regulator_get(dev: &spi->dev, id: "vref" ); |
130 | if (IS_ERR(ptr: state->vref_reg)) |
131 | return PTR_ERR(ptr: state->vref_reg); |
132 | |
133 | ret = regulator_enable(regulator: state->vref_reg); |
134 | if (ret) |
135 | return ret; |
136 | |
137 | ret = devm_add_action_or_reset(&spi->dev, max11100_regulator_disable, |
138 | state->vref_reg); |
139 | if (ret) |
140 | return ret; |
141 | |
142 | return devm_iio_device_register(&spi->dev, indio_dev); |
143 | } |
144 | |
145 | static const struct of_device_id max11100_ids[] = { |
146 | {.compatible = "maxim,max11100" }, |
147 | { }, |
148 | }; |
149 | MODULE_DEVICE_TABLE(of, max11100_ids); |
150 | |
151 | static struct spi_driver max11100_driver = { |
152 | .driver = { |
153 | .name = "max11100" , |
154 | .of_match_table = max11100_ids, |
155 | }, |
156 | .probe = max11100_probe, |
157 | }; |
158 | |
159 | module_spi_driver(max11100_driver); |
160 | |
161 | MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>" ); |
162 | MODULE_DESCRIPTION("Maxim max11100 ADC Driver" ); |
163 | MODULE_LICENSE("GPL v2" ); |
164 | |