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/slab.h> 24 #include <linux/sysfs.h> 25 26 #include <linux/iio/iio.h> 27 #include <linux/iio/sysfs.h> 28 29 /* Measure Relative Humidity, Hold Master Mode */ 30 #define SI7020CMD_RH_HOLD 0xE5 31 /* Measure Temperature, Hold Master Mode */ 32 #define SI7020CMD_TEMP_HOLD 0xE3 33 /* Software Reset */ 34 #define SI7020CMD_RESET 0xFE 35 36 static int si7020_read_raw(struct iio_dev *indio_dev, 37 struct iio_chan_spec const *chan, int *val, 38 int *val2, long mask) 39 { 40 struct i2c_client **client = iio_priv(indio_dev); 41 int ret; 42 43 switch (mask) { 44 case IIO_CHAN_INFO_RAW: 45 ret = i2c_smbus_read_word_swapped(*client, 46 chan->type == IIO_TEMP ? 47 SI7020CMD_TEMP_HOLD : 48 SI7020CMD_RH_HOLD); 49 if (ret < 0) 50 return ret; 51 *val = ret >> 2; 52 /* 53 * Humidity values can slightly exceed the 0-100%RH 54 * range and should be corrected by software 55 */ 56 if (chan->type == IIO_HUMIDITYRELATIVE) 57 *val = clamp_val(*val, 786, 13893); 58 return IIO_VAL_INT; 59 case IIO_CHAN_INFO_SCALE: 60 if (chan->type == IIO_TEMP) 61 *val = 175720; /* = 175.72 * 1000 */ 62 else 63 *val = 125 * 1000; 64 *val2 = 65536 >> 2; 65 return IIO_VAL_FRACTIONAL; 66 case IIO_CHAN_INFO_OFFSET: 67 /* 68 * Since iio_convert_raw_to_processed_unlocked assumes offset 69 * is an integer we have to round these values and lose 70 * accuracy. 71 * Relative humidity will be 0.0032959% too high and 72 * temperature will be 0.00277344 degrees too high. 73 * This is no big deal because it's within the accuracy of the 74 * sensor. 75 */ 76 if (chan->type == IIO_TEMP) 77 *val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */ 78 else 79 *val = -786; /* = -6 * (65536 >> 2) / 125 */ 80 return IIO_VAL_INT; 81 default: 82 break; 83 } 84 85 return -EINVAL; 86 } 87 88 static const struct iio_chan_spec si7020_channels[] = { 89 { 90 .type = IIO_HUMIDITYRELATIVE, 91 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | 92 BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), 93 }, 94 { 95 .type = IIO_TEMP, 96 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | 97 BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), 98 } 99 }; 100 101 static const struct iio_info si7020_info = { 102 .read_raw = si7020_read_raw, 103 }; 104 105 static int si7020_probe(struct i2c_client *client, 106 const struct i2c_device_id *id) 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->dev.parent = &client->dev; 132 indio_dev->name = dev_name(&client->dev); 133 indio_dev->modes = INDIO_DIRECT_MODE; 134 indio_dev->info = &si7020_info; 135 indio_dev->channels = si7020_channels; 136 indio_dev->num_channels = ARRAY_SIZE(si7020_channels); 137 138 return devm_iio_device_register(&client->dev, indio_dev); 139 } 140 141 static const struct i2c_device_id si7020_id[] = { 142 { "si7020", 0 }, 143 { "th06", 0 }, 144 { } 145 }; 146 MODULE_DEVICE_TABLE(i2c, si7020_id); 147 148 static const struct of_device_id si7020_dt_ids[] = { 149 { .compatible = "silabs,si7020" }, 150 { } 151 }; 152 MODULE_DEVICE_TABLE(of, si7020_dt_ids); 153 154 static struct i2c_driver si7020_driver = { 155 .driver = { 156 .name = "si7020", 157 .of_match_table = of_match_ptr(si7020_dt_ids), 158 }, 159 .probe = si7020_probe, 160 .id_table = si7020_id, 161 }; 162 163 module_i2c_driver(si7020_driver); 164 MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors"); 165 MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>"); 166 MODULE_LICENSE("GPL"); 167