1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
4 *
5 * Copyright (C) 2016 Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>
6 */
7 #include <linux/module.h>
8 #include <linux/mod_devicetable.h>
9 #include <linux/spi/spi.h>
10
11 #include <linux/iio/sysfs.h>
12 #include <linux/iio/iio.h>
13
14 #define MAX5487_WRITE_WIPER_A (0x01 << 8)
15 #define MAX5487_WRITE_WIPER_B (0x02 << 8)
16
17 /* copy both wiper regs to NV regs */
18 #define MAX5487_COPY_AB_TO_NV (0x23 << 8)
19 /* copy both NV regs to wiper regs */
20 #define MAX5487_COPY_NV_TO_AB (0x33 << 8)
21
22 #define MAX5487_MAX_POS 255
23
24 struct max5487_data {
25 struct spi_device *spi;
26 int kohms;
27 };
28
29 #define MAX5487_CHANNEL(ch, addr) { \
30 .type = IIO_RESISTANCE, \
31 .indexed = 1, \
32 .output = 1, \
33 .channel = ch, \
34 .address = addr, \
35 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
36 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
37 }
38
39 static const struct iio_chan_spec max5487_channels[] = {
40 MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A),
41 MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B),
42 };
43
max5487_write_cmd(struct spi_device * spi,u16 cmd)44 static int max5487_write_cmd(struct spi_device *spi, u16 cmd)
45 {
46 return spi_write(spi, (const void *) &cmd, sizeof(u16));
47 }
48
max5487_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)49 static int max5487_read_raw(struct iio_dev *indio_dev,
50 struct iio_chan_spec const *chan,
51 int *val, int *val2, long mask)
52 {
53 struct max5487_data *data = iio_priv(indio_dev);
54
55 if (mask != IIO_CHAN_INFO_SCALE)
56 return -EINVAL;
57
58 *val = 1000 * data->kohms;
59 *val2 = MAX5487_MAX_POS;
60
61 return IIO_VAL_FRACTIONAL;
62 }
63
max5487_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)64 static int max5487_write_raw(struct iio_dev *indio_dev,
65 struct iio_chan_spec const *chan,
66 int val, int val2, long mask)
67 {
68 struct max5487_data *data = iio_priv(indio_dev);
69
70 if (mask != IIO_CHAN_INFO_RAW)
71 return -EINVAL;
72
73 if (val < 0 || val > MAX5487_MAX_POS)
74 return -EINVAL;
75
76 return max5487_write_cmd(data->spi, chan->address | val);
77 }
78
79 static const struct iio_info max5487_info = {
80 .read_raw = max5487_read_raw,
81 .write_raw = max5487_write_raw,
82 };
83
max5487_spi_probe(struct spi_device * spi)84 static int max5487_spi_probe(struct spi_device *spi)
85 {
86 struct iio_dev *indio_dev;
87 struct max5487_data *data;
88 const struct spi_device_id *id = spi_get_device_id(spi);
89 int ret;
90
91 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
92 if (!indio_dev)
93 return -ENOMEM;
94
95 spi_set_drvdata(spi, indio_dev);
96 data = iio_priv(indio_dev);
97
98 data->spi = spi;
99 data->kohms = id->driver_data;
100
101 indio_dev->info = &max5487_info;
102 indio_dev->name = id->name;
103 indio_dev->modes = INDIO_DIRECT_MODE;
104 indio_dev->channels = max5487_channels;
105 indio_dev->num_channels = ARRAY_SIZE(max5487_channels);
106
107 /* restore both wiper regs from NV regs */
108 ret = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB);
109 if (ret < 0)
110 return ret;
111
112 return iio_device_register(indio_dev);
113 }
114
max5487_spi_remove(struct spi_device * spi)115 static void max5487_spi_remove(struct spi_device *spi)
116 {
117 struct iio_dev *indio_dev = spi_get_drvdata(spi);
118 int ret;
119
120 iio_device_unregister(indio_dev);
121
122 /* save both wiper regs to NV regs */
123 ret = max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV);
124 if (ret)
125 dev_warn(&spi->dev, "Failed to save wiper regs to NV regs\n");
126 }
127
128 static const struct spi_device_id max5487_id[] = {
129 { "MAX5487", 10 },
130 { "MAX5488", 50 },
131 { "MAX5489", 100 },
132 { }
133 };
134 MODULE_DEVICE_TABLE(spi, max5487_id);
135
136 static const struct acpi_device_id max5487_acpi_match[] = {
137 { "MAX5487", 10 },
138 { "MAX5488", 50 },
139 { "MAX5489", 100 },
140 { },
141 };
142 MODULE_DEVICE_TABLE(acpi, max5487_acpi_match);
143
144 static struct spi_driver max5487_driver = {
145 .driver = {
146 .name = "max5487",
147 .acpi_match_table = max5487_acpi_match,
148 },
149 .id_table = max5487_id,
150 .probe = max5487_spi_probe,
151 .remove = max5487_spi_remove
152 };
153 module_spi_driver(max5487_driver);
154
155 MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>");
156 MODULE_DESCRIPTION("max5487 SPI driver");
157 MODULE_LICENSE("GPL v2");
158