1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Maxim Integrated MAX5481-MAX5484 digital potentiometer driver |
4 | * Copyright 2016 Rockwell Collins |
5 | * |
6 | * Datasheet: |
7 | * https://datasheets.maximintegrated.com/en/ds/MAX5481-MAX5484.pdf |
8 | */ |
9 | |
10 | #include <linux/iio/iio.h> |
11 | #include <linux/iio/sysfs.h> |
12 | #include <linux/module.h> |
13 | #include <linux/mod_devicetable.h> |
14 | #include <linux/property.h> |
15 | #include <linux/spi/spi.h> |
16 | |
17 | /* write wiper reg */ |
18 | #define MAX5481_WRITE_WIPER (0 << 4) |
19 | /* copy wiper reg to NV reg */ |
20 | #define MAX5481_COPY_AB_TO_NV (2 << 4) |
21 | /* copy NV reg to wiper reg */ |
22 | #define MAX5481_COPY_NV_TO_AB (3 << 4) |
23 | |
24 | #define MAX5481_MAX_POS 1023 |
25 | |
26 | enum max5481_variant { |
27 | max5481, |
28 | max5482, |
29 | max5483, |
30 | max5484, |
31 | }; |
32 | |
33 | struct max5481_cfg { |
34 | int kohms; |
35 | }; |
36 | |
37 | static const struct max5481_cfg max5481_cfg[] = { |
38 | [max5481] = { .kohms = 10, }, |
39 | [max5482] = { .kohms = 50, }, |
40 | [max5483] = { .kohms = 10, }, |
41 | [max5484] = { .kohms = 50, }, |
42 | }; |
43 | |
44 | struct max5481_data { |
45 | struct spi_device *spi; |
46 | const struct max5481_cfg *cfg; |
47 | u8 msg[3] __aligned(IIO_DMA_MINALIGN); |
48 | }; |
49 | |
50 | #define MAX5481_CHANNEL { \ |
51 | .type = IIO_RESISTANCE, \ |
52 | .indexed = 1, \ |
53 | .output = 1, \ |
54 | .channel = 0, \ |
55 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ |
56 | .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ |
57 | } |
58 | |
59 | static const struct iio_chan_spec max5481_channels[] = { |
60 | MAX5481_CHANNEL, |
61 | }; |
62 | |
63 | static int max5481_write_cmd(struct max5481_data *data, u8 cmd, u16 val) |
64 | { |
65 | struct spi_device *spi = data->spi; |
66 | |
67 | data->msg[0] = cmd; |
68 | |
69 | switch (cmd) { |
70 | case MAX5481_WRITE_WIPER: |
71 | data->msg[1] = val >> 2; |
72 | data->msg[2] = (val & 0x3) << 6; |
73 | return spi_write(spi, buf: data->msg, len: 3); |
74 | |
75 | case MAX5481_COPY_AB_TO_NV: |
76 | case MAX5481_COPY_NV_TO_AB: |
77 | return spi_write(spi, buf: data->msg, len: 1); |
78 | |
79 | default: |
80 | return -EIO; |
81 | } |
82 | } |
83 | |
84 | static int max5481_read_raw(struct iio_dev *indio_dev, |
85 | struct iio_chan_spec const *chan, |
86 | int *val, int *val2, long mask) |
87 | { |
88 | struct max5481_data *data = iio_priv(indio_dev); |
89 | |
90 | if (mask != IIO_CHAN_INFO_SCALE) |
91 | return -EINVAL; |
92 | |
93 | *val = 1000 * data->cfg->kohms; |
94 | *val2 = MAX5481_MAX_POS; |
95 | |
96 | return IIO_VAL_FRACTIONAL; |
97 | } |
98 | |
99 | static int max5481_write_raw(struct iio_dev *indio_dev, |
100 | struct iio_chan_spec const *chan, |
101 | int val, int val2, long mask) |
102 | { |
103 | struct max5481_data *data = iio_priv(indio_dev); |
104 | |
105 | if (mask != IIO_CHAN_INFO_RAW) |
106 | return -EINVAL; |
107 | |
108 | if (val < 0 || val > MAX5481_MAX_POS) |
109 | return -EINVAL; |
110 | |
111 | return max5481_write_cmd(data, MAX5481_WRITE_WIPER, val); |
112 | } |
113 | |
114 | static const struct iio_info max5481_info = { |
115 | .read_raw = max5481_read_raw, |
116 | .write_raw = max5481_write_raw, |
117 | }; |
118 | |
119 | static const struct of_device_id max5481_match[] = { |
120 | { .compatible = "maxim,max5481" , .data = &max5481_cfg[max5481] }, |
121 | { .compatible = "maxim,max5482" , .data = &max5481_cfg[max5482] }, |
122 | { .compatible = "maxim,max5483" , .data = &max5481_cfg[max5483] }, |
123 | { .compatible = "maxim,max5484" , .data = &max5481_cfg[max5484] }, |
124 | { } |
125 | }; |
126 | MODULE_DEVICE_TABLE(of, max5481_match); |
127 | |
128 | static void max5481_wiper_save(void *data) |
129 | { |
130 | max5481_write_cmd(data, MAX5481_COPY_AB_TO_NV, val: 0); |
131 | } |
132 | |
133 | static int max5481_probe(struct spi_device *spi) |
134 | { |
135 | struct iio_dev *indio_dev; |
136 | struct max5481_data *data; |
137 | const struct spi_device_id *id = spi_get_device_id(sdev: spi); |
138 | int ret; |
139 | |
140 | indio_dev = devm_iio_device_alloc(parent: &spi->dev, sizeof_priv: sizeof(*data)); |
141 | if (!indio_dev) |
142 | return -ENOMEM; |
143 | |
144 | data = iio_priv(indio_dev); |
145 | |
146 | data->spi = spi; |
147 | |
148 | data->cfg = device_get_match_data(dev: &spi->dev); |
149 | if (!data->cfg) |
150 | data->cfg = &max5481_cfg[id->driver_data]; |
151 | |
152 | indio_dev->name = id->name; |
153 | indio_dev->modes = INDIO_DIRECT_MODE; |
154 | |
155 | /* variant specific configuration */ |
156 | indio_dev->info = &max5481_info; |
157 | indio_dev->channels = max5481_channels; |
158 | indio_dev->num_channels = ARRAY_SIZE(max5481_channels); |
159 | |
160 | /* restore wiper from NV */ |
161 | ret = max5481_write_cmd(data, MAX5481_COPY_NV_TO_AB, val: 0); |
162 | if (ret < 0) |
163 | return ret; |
164 | |
165 | ret = devm_add_action(&spi->dev, max5481_wiper_save, data); |
166 | if (ret < 0) |
167 | return ret; |
168 | |
169 | return devm_iio_device_register(&spi->dev, indio_dev); |
170 | } |
171 | |
172 | static const struct spi_device_id max5481_id_table[] = { |
173 | { .name: "max5481" , .driver_data: max5481 }, |
174 | { "max5482" , max5482 }, |
175 | { "max5483" , max5483 }, |
176 | { "max5484" , max5484 }, |
177 | { } |
178 | }; |
179 | MODULE_DEVICE_TABLE(spi, max5481_id_table); |
180 | |
181 | static struct spi_driver max5481_driver = { |
182 | .driver = { |
183 | .name = "max5481" , |
184 | .of_match_table = max5481_match, |
185 | }, |
186 | .probe = max5481_probe, |
187 | .id_table = max5481_id_table, |
188 | }; |
189 | |
190 | module_spi_driver(max5481_driver); |
191 | |
192 | MODULE_AUTHOR("Maury Anderson <maury.anderson@rockwellcollins.com>" ); |
193 | MODULE_DESCRIPTION("max5481 SPI driver" ); |
194 | MODULE_LICENSE("GPL v2" ); |
195 | |