Slawomir Stepien | fbbc5e7 | 2016-04-10 13:23:09 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Maxim Integrated DS1803 digital potentiometer driver |
| 3 | * Copyright (c) 2016 Slawomir Stepien |
| 4 | * |
| 5 | * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf |
| 6 | * |
| 7 | * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address |
| 8 | * ds1803 2 256 10, 50, 100 0101xxx |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or modify it |
| 11 | * under the terms of the GNU General Public License version 2 as published by |
| 12 | * the Free Software Foundation. |
| 13 | */ |
| 14 | |
| 15 | #include <linux/err.h> |
| 16 | #include <linux/export.h> |
| 17 | #include <linux/i2c.h> |
| 18 | #include <linux/iio/iio.h> |
| 19 | #include <linux/module.h> |
| 20 | #include <linux/of.h> |
| 21 | |
| 22 | #define DS1803_MAX_POS 255 |
| 23 | #define DS1803_WRITE(chan) (0xa8 | ((chan) + 1)) |
| 24 | |
| 25 | enum ds1803_type { |
| 26 | DS1803_010, |
| 27 | DS1803_050, |
| 28 | DS1803_100, |
| 29 | }; |
| 30 | |
| 31 | struct ds1803_cfg { |
| 32 | int kohms; |
| 33 | }; |
| 34 | |
| 35 | static const struct ds1803_cfg ds1803_cfg[] = { |
| 36 | [DS1803_010] = { .kohms = 10, }, |
| 37 | [DS1803_050] = { .kohms = 50, }, |
| 38 | [DS1803_100] = { .kohms = 100, }, |
| 39 | }; |
| 40 | |
| 41 | struct ds1803_data { |
| 42 | struct i2c_client *client; |
| 43 | const struct ds1803_cfg *cfg; |
| 44 | }; |
| 45 | |
| 46 | #define DS1803_CHANNEL(ch) { \ |
| 47 | .type = IIO_RESISTANCE, \ |
| 48 | .indexed = 1, \ |
| 49 | .output = 1, \ |
| 50 | .channel = (ch), \ |
| 51 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ |
| 52 | .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ |
| 53 | } |
| 54 | |
| 55 | static const struct iio_chan_spec ds1803_channels[] = { |
| 56 | DS1803_CHANNEL(0), |
| 57 | DS1803_CHANNEL(1), |
| 58 | }; |
| 59 | |
| 60 | static int ds1803_read_raw(struct iio_dev *indio_dev, |
| 61 | struct iio_chan_spec const *chan, |
| 62 | int *val, int *val2, long mask) |
| 63 | { |
| 64 | struct ds1803_data *data = iio_priv(indio_dev); |
| 65 | int pot = chan->channel; |
| 66 | int ret; |
| 67 | u8 result[indio_dev->num_channels]; |
| 68 | |
| 69 | switch (mask) { |
| 70 | case IIO_CHAN_INFO_RAW: |
| 71 | ret = i2c_master_recv(data->client, result, |
| 72 | indio_dev->num_channels); |
| 73 | if (ret < 0) |
| 74 | return ret; |
| 75 | |
| 76 | *val = result[pot]; |
| 77 | return IIO_VAL_INT; |
| 78 | |
| 79 | case IIO_CHAN_INFO_SCALE: |
| 80 | *val = 1000 * data->cfg->kohms; |
| 81 | *val2 = DS1803_MAX_POS; |
| 82 | return IIO_VAL_FRACTIONAL; |
| 83 | } |
| 84 | |
| 85 | return -EINVAL; |
| 86 | } |
| 87 | |
| 88 | static int ds1803_write_raw(struct iio_dev *indio_dev, |
| 89 | struct iio_chan_spec const *chan, |
| 90 | int val, int val2, long mask) |
| 91 | { |
| 92 | struct ds1803_data *data = iio_priv(indio_dev); |
| 93 | int pot = chan->channel; |
| 94 | |
| 95 | if (val2 != 0) |
| 96 | return -EINVAL; |
| 97 | |
| 98 | switch (mask) { |
| 99 | case IIO_CHAN_INFO_RAW: |
| 100 | if (val > DS1803_MAX_POS || val < 0) |
| 101 | return -EINVAL; |
| 102 | break; |
| 103 | default: |
| 104 | return -EINVAL; |
| 105 | } |
| 106 | |
| 107 | return i2c_smbus_write_byte_data(data->client, DS1803_WRITE(pot), val); |
| 108 | } |
| 109 | |
| 110 | static const struct iio_info ds1803_info = { |
| 111 | .read_raw = ds1803_read_raw, |
| 112 | .write_raw = ds1803_write_raw, |
| 113 | .driver_module = THIS_MODULE, |
| 114 | }; |
| 115 | |
| 116 | static int ds1803_probe(struct i2c_client *client, |
| 117 | const struct i2c_device_id *id) |
| 118 | { |
| 119 | struct device *dev = &client->dev; |
| 120 | struct ds1803_data *data; |
| 121 | struct iio_dev *indio_dev; |
| 122 | |
| 123 | indio_dev = devm_iio_device_alloc(dev, sizeof(*data)); |
| 124 | if (!indio_dev) |
| 125 | return -ENOMEM; |
| 126 | |
| 127 | i2c_set_clientdata(client, indio_dev); |
| 128 | |
| 129 | data = iio_priv(indio_dev); |
| 130 | data->client = client; |
| 131 | data->cfg = &ds1803_cfg[id->driver_data]; |
| 132 | |
| 133 | indio_dev->dev.parent = dev; |
| 134 | indio_dev->info = &ds1803_info; |
| 135 | indio_dev->channels = ds1803_channels; |
| 136 | indio_dev->num_channels = ARRAY_SIZE(ds1803_channels); |
| 137 | indio_dev->name = client->name; |
| 138 | |
| 139 | return devm_iio_device_register(dev, indio_dev); |
| 140 | } |
| 141 | |
| 142 | #if defined(CONFIG_OF) |
| 143 | static const struct of_device_id ds1803_dt_ids[] = { |
| 144 | { .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] }, |
| 145 | { .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] }, |
| 146 | { .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] }, |
| 147 | {} |
| 148 | }; |
| 149 | MODULE_DEVICE_TABLE(of, ds1803_dt_ids); |
| 150 | #endif /* CONFIG_OF */ |
| 151 | |
| 152 | static const struct i2c_device_id ds1803_id[] = { |
| 153 | { "ds1803-010", DS1803_010 }, |
| 154 | { "ds1803-050", DS1803_050 }, |
| 155 | { "ds1803-100", DS1803_100 }, |
| 156 | {} |
| 157 | }; |
| 158 | MODULE_DEVICE_TABLE(i2c, ds1803_id); |
| 159 | |
| 160 | static struct i2c_driver ds1803_driver = { |
| 161 | .driver = { |
| 162 | .name = "ds1803", |
| 163 | .of_match_table = of_match_ptr(ds1803_dt_ids), |
| 164 | }, |
| 165 | .probe = ds1803_probe, |
| 166 | .id_table = ds1803_id, |
| 167 | }; |
| 168 | |
| 169 | module_i2c_driver(ds1803_driver); |
| 170 | |
| 171 | MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>"); |
| 172 | MODULE_DESCRIPTION("DS1803 digital potentiometer"); |
| 173 | MODULE_LICENSE("GPL v2"); |