2 * Maxim Integrated MAX5481-MAX5484 digital potentiometer driver
3 * Copyright 2016 Rockwell Collins
6 * http://datasheets.maximintegrated.com/en/ds/MAX5481-MAX5484.pdf
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the gnu general public license version 2 as
10 * published by the free software foundation.
14 #include <linux/acpi.h>
15 #include <linux/iio/iio.h>
16 #include <linux/iio/sysfs.h>
17 #include <linux/module.h>
19 #include <linux/of_device.h>
20 #include <linux/spi/spi.h>
23 #define MAX5481_WRITE_WIPER (0 << 4)
24 /* copy wiper reg to NV reg */
25 #define MAX5481_COPY_AB_TO_NV (2 << 4)
26 /* copy NV reg to wiper reg */
27 #define MAX5481_COPY_NV_TO_AB (3 << 4)
29 #define MAX5481_MAX_POS 1023
31 enum max5481_variant {
42 static const struct max5481_cfg max5481_cfg[] = {
43 [max5481] = { .kohms = 10, },
44 [max5482] = { .kohms = 50, },
45 [max5483] = { .kohms = 10, },
46 [max5484] = { .kohms = 50, },
50 struct spi_device *spi;
51 const struct max5481_cfg *cfg;
52 u8 msg[3] ____cacheline_aligned;
55 #define MAX5481_CHANNEL { \
56 .type = IIO_RESISTANCE, \
60 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
61 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
64 static const struct iio_chan_spec max5481_channels[] = {
68 static int max5481_write_cmd(struct max5481_data *data, u8 cmd, u16 val)
70 struct spi_device *spi = data->spi;
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);
80 case MAX5481_COPY_AB_TO_NV:
81 case MAX5481_COPY_NV_TO_AB:
82 return spi_write(spi, data->msg, 1);
89 static int max5481_read_raw(struct iio_dev *indio_dev,
90 struct iio_chan_spec const *chan,
91 int *val, int *val2, long mask)
93 struct max5481_data *data = iio_priv(indio_dev);
95 if (mask != IIO_CHAN_INFO_SCALE)
98 *val = 1000 * data->cfg->kohms;
99 *val2 = MAX5481_MAX_POS;
101 return IIO_VAL_FRACTIONAL;
104 static int max5481_write_raw(struct iio_dev *indio_dev,
105 struct iio_chan_spec const *chan,
106 int val, int val2, long mask)
108 struct max5481_data *data = iio_priv(indio_dev);
110 if (mask != IIO_CHAN_INFO_RAW)
113 if (val < 0 || val > MAX5481_MAX_POS)
116 return max5481_write_cmd(data, MAX5481_WRITE_WIPER, val);
119 static const struct iio_info max5481_info = {
120 .read_raw = max5481_read_raw,
121 .write_raw = max5481_write_raw,
124 #if defined(CONFIG_OF)
125 static const struct of_device_id max5481_match[] = {
126 { .compatible = "maxim,max5481", .data = &max5481_cfg[max5481] },
127 { .compatible = "maxim,max5482", .data = &max5481_cfg[max5482] },
128 { .compatible = "maxim,max5483", .data = &max5481_cfg[max5483] },
129 { .compatible = "maxim,max5484", .data = &max5481_cfg[max5484] },
132 MODULE_DEVICE_TABLE(of, max5481_match);
135 static int max5481_probe(struct spi_device *spi)
137 struct iio_dev *indio_dev;
138 struct max5481_data *data;
139 const struct spi_device_id *id = spi_get_device_id(spi);
142 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
146 dev_set_drvdata(&spi->dev, indio_dev);
147 data = iio_priv(indio_dev);
151 data->cfg = of_device_get_match_data(&spi->dev);
153 data->cfg = &max5481_cfg[id->driver_data];
155 indio_dev->name = id->name;
156 indio_dev->dev.parent = &spi->dev;
157 indio_dev->modes = INDIO_DIRECT_MODE;
159 /* variant specific configuration */
160 indio_dev->info = &max5481_info;
161 indio_dev->channels = max5481_channels;
162 indio_dev->num_channels = ARRAY_SIZE(max5481_channels);
164 /* restore wiper from NV */
165 ret = max5481_write_cmd(data, MAX5481_COPY_NV_TO_AB, 0);
169 return iio_device_register(indio_dev);
172 static int max5481_remove(struct spi_device *spi)
174 struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
175 struct max5481_data *data = iio_priv(indio_dev);
177 iio_device_unregister(indio_dev);
179 /* save wiper reg to NV reg */
180 return max5481_write_cmd(data, MAX5481_COPY_AB_TO_NV, 0);
183 static const struct spi_device_id max5481_id_table[] = {
184 { "max5481", max5481 },
185 { "max5482", max5482 },
186 { "max5483", max5483 },
187 { "max5484", max5484 },
190 MODULE_DEVICE_TABLE(spi, max5481_id_table);
192 #if defined(CONFIG_ACPI)
193 static const struct acpi_device_id max5481_acpi_match[] = {
194 { "max5481", max5481 },
195 { "max5482", max5482 },
196 { "max5483", max5483 },
197 { "max5484", max5484 },
200 MODULE_DEVICE_TABLE(acpi, max5481_acpi_match);
203 static struct spi_driver max5481_driver = {
206 .of_match_table = of_match_ptr(max5481_match),
207 .acpi_match_table = ACPI_PTR(max5481_acpi_match),
209 .probe = max5481_probe,
210 .remove = max5481_remove,
211 .id_table = max5481_id_table,
214 module_spi_driver(max5481_driver);
216 MODULE_AUTHOR("Maury Anderson <maury.anderson@rockwellcollins.com>");
217 MODULE_DESCRIPTION("max5481 SPI driver");
218 MODULE_LICENSE("GPL v2");