1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors 4 * Copyright (c) 2013,2014 Uplogix, Inc. 5 * David Barksdale <dbarksdale@uplogix.com> 6 */ 7 8 /* 9 * The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors 10 * are i2c devices which have an identical programming interface for 11 * measuring relative humidity and temperature. The Si7013 has an additional 12 * temperature input which this driver does not support. 13 * 14 * Data Sheets: 15 * Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf 16 * Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf 17 * Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf 18 */ 19 20 #include <linux/delay.h> 21 #include <linux/i2c.h> 22 #include <linux/module.h> 23 #include <linux/mod_devicetable.h> 24 #include <linux/slab.h> 25 #include <linux/sysfs.h> 26 27 #include <linux/iio/iio.h> 28 #include <linux/iio/sysfs.h> 29 30 /* Measure Relative Humidity, Hold Master Mode */ 31 #define SI7020CMD_RH_HOLD 0xE5 32 /* Measure Temperature, Hold Master Mode */ 33 #define SI7020CMD_TEMP_HOLD 0xE3 34 /* Software Reset */ 35 #define SI7020CMD_RESET 0xFE 36 37 static int si7020_read_raw(struct iio_dev *indio_dev, 38 struct iio_chan_spec const *chan, int *val, 39 int *val2, long mask) 40 { 41 struct i2c_client **client = iio_priv(indio_dev); 42 int ret; 43 44 switch (mask) { 45 case IIO_CHAN_INFO_RAW: 46 ret = i2c_smbus_read_word_swapped(*client, 47 chan->type == IIO_TEMP ? 48 SI7020CMD_TEMP_HOLD : 49 SI7020CMD_RH_HOLD); 50 if (ret < 0) 51 return ret; 52 *val = ret >> 2; 53 /* 54 * Humidity values can slightly exceed the 0-100%RH 55 * range and should be corrected by software 56 */ 57 if (chan->type == IIO_HUMIDITYRELATIVE) 58 *val = clamp_val(*val, 786, 13893); 59 return IIO_VAL_INT; 60 case IIO_CHAN_INFO_SCALE: 61 if (chan->type == IIO_TEMP) 62 *val = 175720; /* = 175.72 * 1000 */ 63 else 64 *val = 125 * 1000; 65 *val2 = 65536 >> 2; 66 return IIO_VAL_FRACTIONAL; 67 case IIO_CHAN_INFO_OFFSET: 68 /* 69 * Since iio_convert_raw_to_processed_unlocked assumes offset 70 * is an integer we have to round these values and lose 71 * accuracy. 72 * Relative humidity will be 0.0032959% too high and 73 * temperature will be 0.00277344 degrees too high. 74 * This is no big deal because it's within the accuracy of the 75 * sensor. 76 */ 77 if (chan->type == IIO_TEMP) 78 *val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */ 79 else 80 *val = -786; /* = -6 * (65536 >> 2) / 125 */ 81 return IIO_VAL_INT; 82 default: 83 break; 84 } 85 86 return -EINVAL; 87 } 88 89 static const struct iio_chan_spec si7020_channels[] = { 90 { 91 .type = IIO_HUMIDITYRELATIVE, 92 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | 93 BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), 94 }, 95 { 96 .type = IIO_TEMP, 97 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | 98 BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), 99 } 100 }; 101 102 static const struct iio_info si7020_info = { 103 .read_raw = si7020_read_raw, 104 }; 105 106 static int si7020_probe(struct i2c_client *client) 107 { 108 struct iio_dev *indio_dev; 109 struct i2c_client **data; 110 int ret; 111 112 if (!i2c_check_functionality(client->adapter, 113 I2C_FUNC_SMBUS_WRITE_BYTE | 114 I2C_FUNC_SMBUS_READ_WORD_DATA)) 115 return -EOPNOTSUPP; 116 117 /* Reset device, loads default settings. */ 118 ret = i2c_smbus_write_byte(client, SI7020CMD_RESET); 119 if (ret < 0) 120 return ret; 121 /* Wait the maximum power-up time after software reset. */ 122 msleep(15); 123 124 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); 125 if (!indio_dev) 126 return -ENOMEM; 127 128 data = iio_priv(indio_dev); 129 *data = client; 130 131 indio_dev->name = dev_name(&client->dev); 132 indio_dev->modes = INDIO_DIRECT_MODE; 133 indio_dev->info = &si7020_info; 134 indio_dev->channels = si7020_channels; 135 indio_dev->num_channels = ARRAY_SIZE(si7020_channels); 136 137 return devm_iio_device_register(&client->dev, indio_dev); 138 } 139 140 static const struct i2c_device_id si7020_id[] = { 141 { "si7020", 0 }, 142 { "th06", 0 }, 143 { } 144 }; 145 MODULE_DEVICE_TABLE(i2c, si7020_id); 146 147 static const struct of_device_id si7020_dt_ids[] = { 148 { .compatible = "silabs,si7020" }, 149 { } 150 }; 151 MODULE_DEVICE_TABLE(of, si7020_dt_ids); 152 153 static struct i2c_driver si7020_driver = { 154 .driver = { 155 .name = "si7020", 156 .of_match_table = si7020_dt_ids, 157 }, 158 .probe_new = si7020_probe, 159 .id_table = si7020_id, 160 }; 161 162 module_i2c_driver(si7020_driver); 163 MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors"); 164 MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>"); 165 MODULE_LICENSE("GPL"); 166