1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S90 |
4 | * |
5 | * Copyright (c) 2010-2010 Analog Devices Inc. |
6 | */ |
7 | #include <linux/types.h> |
8 | #include <linux/mutex.h> |
9 | #include <linux/device.h> |
10 | #include <linux/spi/spi.h> |
11 | #include <linux/slab.h> |
12 | #include <linux/sysfs.h> |
13 | #include <linux/module.h> |
14 | |
15 | #include <linux/iio/iio.h> |
16 | #include <linux/iio/sysfs.h> |
17 | |
18 | /* |
19 | * Although chip's max frequency is 2Mhz, it needs 600ns between CS and the |
20 | * first falling edge of SCLK, so frequency should be at most 1 / (2 * 6e-7) |
21 | */ |
22 | #define AD2S90_MAX_SPI_FREQ_HZ 830000 |
23 | |
24 | struct ad2s90_state { |
25 | struct mutex lock; /* lock to protect rx buffer */ |
26 | struct spi_device *sdev; |
27 | u8 rx[2] __aligned(IIO_DMA_MINALIGN); |
28 | }; |
29 | |
30 | static int ad2s90_read_raw(struct iio_dev *indio_dev, |
31 | struct iio_chan_spec const *chan, |
32 | int *val, |
33 | int *val2, |
34 | long m) |
35 | { |
36 | int ret; |
37 | struct ad2s90_state *st = iio_priv(indio_dev); |
38 | |
39 | if (chan->type != IIO_ANGL) |
40 | return -EINVAL; |
41 | |
42 | switch (m) { |
43 | case IIO_CHAN_INFO_SCALE: |
44 | /* 2 * Pi / 2^12 */ |
45 | *val = 6283; /* mV */ |
46 | *val2 = 12; |
47 | return IIO_VAL_FRACTIONAL_LOG2; |
48 | case IIO_CHAN_INFO_RAW: |
49 | mutex_lock(&st->lock); |
50 | ret = spi_read(spi: st->sdev, buf: st->rx, len: 2); |
51 | if (ret < 0) { |
52 | mutex_unlock(lock: &st->lock); |
53 | return ret; |
54 | } |
55 | *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4); |
56 | |
57 | mutex_unlock(lock: &st->lock); |
58 | |
59 | return IIO_VAL_INT; |
60 | default: |
61 | break; |
62 | } |
63 | |
64 | return -EINVAL; |
65 | } |
66 | |
67 | static const struct iio_info ad2s90_info = { |
68 | .read_raw = ad2s90_read_raw, |
69 | }; |
70 | |
71 | static const struct iio_chan_spec ad2s90_chan = { |
72 | .type = IIO_ANGL, |
73 | .indexed = 1, |
74 | .channel = 0, |
75 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), |
76 | }; |
77 | |
78 | static int ad2s90_probe(struct spi_device *spi) |
79 | { |
80 | struct iio_dev *indio_dev; |
81 | struct ad2s90_state *st; |
82 | |
83 | if (spi->max_speed_hz > AD2S90_MAX_SPI_FREQ_HZ) { |
84 | dev_err(&spi->dev, "SPI CLK, %d Hz exceeds %d Hz\n" , |
85 | spi->max_speed_hz, AD2S90_MAX_SPI_FREQ_HZ); |
86 | return -EINVAL; |
87 | } |
88 | |
89 | indio_dev = devm_iio_device_alloc(parent: &spi->dev, sizeof_priv: sizeof(*st)); |
90 | if (!indio_dev) |
91 | return -ENOMEM; |
92 | st = iio_priv(indio_dev); |
93 | spi_set_drvdata(spi, data: indio_dev); |
94 | |
95 | mutex_init(&st->lock); |
96 | st->sdev = spi; |
97 | indio_dev->info = &ad2s90_info; |
98 | indio_dev->modes = INDIO_DIRECT_MODE; |
99 | indio_dev->channels = &ad2s90_chan; |
100 | indio_dev->num_channels = 1; |
101 | indio_dev->name = spi_get_device_id(sdev: spi)->name; |
102 | |
103 | return devm_iio_device_register(indio_dev->dev.parent, indio_dev); |
104 | } |
105 | |
106 | static const struct of_device_id ad2s90_of_match[] = { |
107 | { .compatible = "adi,ad2s90" , }, |
108 | {} |
109 | }; |
110 | MODULE_DEVICE_TABLE(of, ad2s90_of_match); |
111 | |
112 | static const struct spi_device_id ad2s90_id[] = { |
113 | { "ad2s90" }, |
114 | {} |
115 | }; |
116 | MODULE_DEVICE_TABLE(spi, ad2s90_id); |
117 | |
118 | static struct spi_driver ad2s90_driver = { |
119 | .driver = { |
120 | .name = "ad2s90" , |
121 | .of_match_table = ad2s90_of_match, |
122 | }, |
123 | .probe = ad2s90_probe, |
124 | .id_table = ad2s90_id, |
125 | }; |
126 | module_spi_driver(ad2s90_driver); |
127 | |
128 | MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>" ); |
129 | MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver" ); |
130 | MODULE_LICENSE("GPL v2" ); |
131 | |