1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Maxim Integrated MAX5432-MAX5435 digital potentiometer driver 4 * Copyright (C) 2019 Martin Kaiser <martin@kaiser.cx> 5 * 6 * Datasheet: 7 * https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf 8 */ 9 10 #include <linux/i2c.h> 11 #include <linux/iio/iio.h> 12 #include <linux/limits.h> 13 #include <linux/module.h> 14 #include <linux/mod_devicetable.h> 15 #include <linux/property.h> 16 17 /* All chip variants have 32 wiper positions. */ 18 #define MAX5432_MAX_POS 31 19 20 #define MAX5432_OHM_50K (50 * 1000) 21 #define MAX5432_OHM_100K (100 * 1000) 22 23 /* Update the volatile (currently active) setting. */ 24 #define MAX5432_CMD_VREG 0x11 25 26 struct max5432_data { 27 struct i2c_client *client; 28 unsigned long ohm; 29 }; 30 31 static const struct iio_chan_spec max5432_channels[] = { 32 { 33 .type = IIO_RESISTANCE, 34 .indexed = 1, 35 .output = 1, 36 .channel = 0, 37 .address = MAX5432_CMD_VREG, 38 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), 39 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), 40 } 41 }; 42 43 static int max5432_read_raw(struct iio_dev *indio_dev, 44 struct iio_chan_spec const *chan, 45 int *val, int *val2, long mask) 46 { 47 struct max5432_data *data = iio_priv(indio_dev); 48 49 if (mask != IIO_CHAN_INFO_SCALE) 50 return -EINVAL; 51 52 if (unlikely(data->ohm > INT_MAX)) 53 return -ERANGE; 54 55 *val = data->ohm; 56 *val2 = MAX5432_MAX_POS; 57 58 return IIO_VAL_FRACTIONAL; 59 } 60 61 static int max5432_write_raw(struct iio_dev *indio_dev, 62 struct iio_chan_spec const *chan, 63 int val, int val2, long mask) 64 { 65 struct max5432_data *data = iio_priv(indio_dev); 66 u8 data_byte; 67 68 if (mask != IIO_CHAN_INFO_RAW) 69 return -EINVAL; 70 71 if (val < 0 || val > MAX5432_MAX_POS) 72 return -EINVAL; 73 74 if (val2 != 0) 75 return -EINVAL; 76 77 /* Wiper position is in bits D7-D3. (D2-D0 are don't care bits.) */ 78 data_byte = val << 3; 79 return i2c_smbus_write_byte_data(data->client, chan->address, 80 data_byte); 81 } 82 83 static const struct iio_info max5432_info = { 84 .read_raw = max5432_read_raw, 85 .write_raw = max5432_write_raw, 86 }; 87 88 static int max5432_probe(struct i2c_client *client, 89 const struct i2c_device_id *id) 90 { 91 struct device *dev = &client->dev; 92 struct iio_dev *indio_dev; 93 struct max5432_data *data; 94 95 indio_dev = devm_iio_device_alloc(dev, sizeof(struct max5432_data)); 96 if (!indio_dev) 97 return -ENOMEM; 98 99 i2c_set_clientdata(client, indio_dev); 100 101 data = iio_priv(indio_dev); 102 data->client = client; 103 data->ohm = (unsigned long)device_get_match_data(dev); 104 105 indio_dev->info = &max5432_info; 106 indio_dev->channels = max5432_channels; 107 indio_dev->num_channels = ARRAY_SIZE(max5432_channels); 108 indio_dev->name = client->name; 109 110 return devm_iio_device_register(dev, indio_dev); 111 } 112 113 static const struct of_device_id max5432_dt_ids[] = { 114 { .compatible = "maxim,max5432", .data = (void *)MAX5432_OHM_50K }, 115 { .compatible = "maxim,max5433", .data = (void *)MAX5432_OHM_100K }, 116 { .compatible = "maxim,max5434", .data = (void *)MAX5432_OHM_50K }, 117 { .compatible = "maxim,max5435", .data = (void *)MAX5432_OHM_100K }, 118 { /* sentinel */ } 119 }; 120 MODULE_DEVICE_TABLE(of, max5432_dt_ids); 121 122 static struct i2c_driver max5432_driver = { 123 .driver = { 124 .name = "max5432", 125 .of_match_table = max5432_dt_ids, 126 }, 127 .probe = max5432_probe, 128 }; 129 130 module_i2c_driver(max5432_driver); 131 132 MODULE_AUTHOR("Martin Kaiser <martin@kaiser.cx>"); 133 MODULE_DESCRIPTION("max5432-max5435 digital potentiometers"); 134 MODULE_LICENSE("GPL v2"); 135