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[ARRAY_SIZE(ds1803_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 }; 114 115 static int ds1803_probe(struct i2c_client *client, 116 const struct i2c_device_id *id) 117 { 118 struct device *dev = &client->dev; 119 struct ds1803_data *data; 120 struct iio_dev *indio_dev; 121 122 indio_dev = devm_iio_device_alloc(dev, sizeof(*data)); 123 if (!indio_dev) 124 return -ENOMEM; 125 126 i2c_set_clientdata(client, indio_dev); 127 128 data = iio_priv(indio_dev); 129 data->client = client; 130 data->cfg = &ds1803_cfg[id->driver_data]; 131 132 indio_dev->dev.parent = dev; 133 indio_dev->info = &ds1803_info; 134 indio_dev->channels = ds1803_channels; 135 indio_dev->num_channels = ARRAY_SIZE(ds1803_channels); 136 indio_dev->name = client->name; 137 138 return devm_iio_device_register(dev, indio_dev); 139 } 140 141 #if defined(CONFIG_OF) 142 static const struct of_device_id ds1803_dt_ids[] = { 143 { .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] }, 144 { .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] }, 145 { .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] }, 146 {} 147 }; 148 MODULE_DEVICE_TABLE(of, ds1803_dt_ids); 149 #endif /* CONFIG_OF */ 150 151 static const struct i2c_device_id ds1803_id[] = { 152 { "ds1803-010", DS1803_010 }, 153 { "ds1803-050", DS1803_050 }, 154 { "ds1803-100", DS1803_100 }, 155 {} 156 }; 157 MODULE_DEVICE_TABLE(i2c, ds1803_id); 158 159 static struct i2c_driver ds1803_driver = { 160 .driver = { 161 .name = "ds1803", 162 .of_match_table = of_match_ptr(ds1803_dt_ids), 163 }, 164 .probe = ds1803_probe, 165 .id_table = ds1803_id, 166 }; 167 168 module_i2c_driver(ds1803_driver); 169 170 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>"); 171 MODULE_DESCRIPTION("DS1803 digital potentiometer"); 172 MODULE_LICENSE("GPL v2"); 173