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14#include <linux/acpi.h>
15#include <linux/iio/iio.h>
16#include <linux/iio/sysfs.h>
17#include <linux/module.h>
18#include <linux/of.h>
19#include <linux/of_device.h>
20#include <linux/spi/spi.h>
21
22
23#define MAX5481_WRITE_WIPER (0 << 4)
24
25#define MAX5481_COPY_AB_TO_NV (2 << 4)
26
27#define MAX5481_COPY_NV_TO_AB (3 << 4)
28
29#define MAX5481_MAX_POS 1023
30
31enum max5481_variant {
32 max5481,
33 max5482,
34 max5483,
35 max5484,
36};
37
38struct max5481_cfg {
39 int kohms;
40};
41
42static const struct max5481_cfg max5481_cfg[] = {
43 [max5481] = { .kohms = 10, },
44 [max5482] = { .kohms = 50, },
45 [max5483] = { .kohms = 10, },
46 [max5484] = { .kohms = 50, },
47};
48
49struct max5481_data {
50 struct spi_device *spi;
51 const struct max5481_cfg *cfg;
52 u8 msg[3] ____cacheline_aligned;
53};
54
55#define MAX5481_CHANNEL { \
56 .type = IIO_RESISTANCE, \
57 .indexed = 1, \
58 .output = 1, \
59 .channel = 0, \
60 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
61 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
62}
63
64static const struct iio_chan_spec max5481_channels[] = {
65 MAX5481_CHANNEL,
66};
67
68static int max5481_write_cmd(struct max5481_data *data, u8 cmd, u16 val)
69{
70 struct spi_device *spi = data->spi;
71
72 data->msg[0] = cmd;
73
74 switch (cmd) {
75 case MAX5481_WRITE_WIPER:
76 data->msg[1] = val >> 2;
77 data->msg[2] = (val & 0x3) << 6;
78 return spi_write(spi, data->msg, 3);
79
80 case MAX5481_COPY_AB_TO_NV:
81 case MAX5481_COPY_NV_TO_AB:
82 return spi_write(spi, data->msg, 1);
83
84 default:
85 return -EIO;
86 }
87}
88
89static int max5481_read_raw(struct iio_dev *indio_dev,
90 struct iio_chan_spec const *chan,
91 int *val, int *val2, long mask)
92{
93 struct max5481_data *data = iio_priv(indio_dev);
94
95 if (mask != IIO_CHAN_INFO_SCALE)
96 return -EINVAL;
97
98 *val = 1000 * data->cfg->kohms;
99 *val2 = MAX5481_MAX_POS;
100
101 return IIO_VAL_FRACTIONAL;
102}
103
104static int max5481_write_raw(struct iio_dev *indio_dev,
105 struct iio_chan_spec const *chan,
106 int val, int val2, long mask)
107{
108 struct max5481_data *data = iio_priv(indio_dev);
109
110 if (mask != IIO_CHAN_INFO_RAW)
111 return -EINVAL;
112
113 if (val < 0 || val > MAX5481_MAX_POS)
114 return -EINVAL;
115
116 return max5481_write_cmd(data, MAX5481_WRITE_WIPER, val);
117}
118
119static const struct iio_info max5481_info = {
120 .read_raw = max5481_read_raw,
121 .write_raw = max5481_write_raw,
122 .driver_module = THIS_MODULE,
123};
124
125#if defined(CONFIG_OF)
126static const struct of_device_id max5481_match[] = {
127 { .compatible = "maxim,max5481", .data = &max5481_cfg[max5481] },
128 { .compatible = "maxim,max5482", .data = &max5481_cfg[max5482] },
129 { .compatible = "maxim,max5483", .data = &max5481_cfg[max5483] },
130 { .compatible = "maxim,max5484", .data = &max5481_cfg[max5484] },
131 { }
132};
133MODULE_DEVICE_TABLE(of, max5481_match);
134#endif
135
136static int max5481_probe(struct spi_device *spi)
137{
138 struct iio_dev *indio_dev;
139 struct max5481_data *data;
140 const struct spi_device_id *id = spi_get_device_id(spi);
141 const struct of_device_id *match;
142 int ret;
143
144 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
145 if (!indio_dev)
146 return -ENOMEM;
147
148 dev_set_drvdata(&spi->dev, indio_dev);
149 data = iio_priv(indio_dev);
150
151 data->spi = spi;
152
153 match = of_match_device(of_match_ptr(max5481_match), &spi->dev);
154 if (match)
155 data->cfg = of_device_get_match_data(&spi->dev);
156 else
157 data->cfg = &max5481_cfg[id->driver_data];
158
159 indio_dev->name = id->name;
160 indio_dev->dev.parent = &spi->dev;
161 indio_dev->modes = INDIO_DIRECT_MODE;
162
163
164 indio_dev->info = &max5481_info;
165 indio_dev->channels = max5481_channels;
166 indio_dev->num_channels = ARRAY_SIZE(max5481_channels);
167
168
169 ret = max5481_write_cmd(data, MAX5481_COPY_NV_TO_AB, 0);
170 if (ret < 0)
171 return ret;
172
173 return iio_device_register(indio_dev);
174}
175
176static int max5481_remove(struct spi_device *spi)
177{
178 struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
179 struct max5481_data *data = iio_priv(indio_dev);
180
181 iio_device_unregister(indio_dev);
182
183
184 return max5481_write_cmd(data, MAX5481_COPY_AB_TO_NV, 0);
185}
186
187static const struct spi_device_id max5481_id_table[] = {
188 { "max5481", max5481 },
189 { "max5482", max5482 },
190 { "max5483", max5483 },
191 { "max5484", max5484 },
192 { }
193};
194MODULE_DEVICE_TABLE(spi, max5481_id_table);
195
196#if defined(CONFIG_ACPI)
197static const struct acpi_device_id max5481_acpi_match[] = {
198 { "max5481", max5481 },
199 { "max5482", max5482 },
200 { "max5483", max5483 },
201 { "max5484", max5484 },
202 { }
203};
204MODULE_DEVICE_TABLE(acpi, max5481_acpi_match);
205#endif
206
207static struct spi_driver max5481_driver = {
208 .driver = {
209 .name = "max5481",
210 .owner = THIS_MODULE,
211 .of_match_table = of_match_ptr(max5481_match),
212 .acpi_match_table = ACPI_PTR(max5481_acpi_match),
213 },
214 .probe = max5481_probe,
215 .remove = max5481_remove,
216 .id_table = max5481_id_table,
217};
218
219module_spi_driver(max5481_driver);
220
221MODULE_AUTHOR("Maury Anderson <maury.anderson@rockwellcollins.com>");
222MODULE_DESCRIPTION("max5481 SPI driver");
223MODULE_LICENSE("GPL v2");
224
