David Barksdale | 064a746 | 2014-09-29 13:28:55 -0500 | [diff] [blame] | 1 | /* |
| 2 | * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors |
| 3 | * Copyright (c) 2013,2014 Uplogix, Inc. |
| 4 | * David Barksdale <dbarksdale@uplogix.com> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify it |
| 7 | * under the terms and conditions of the GNU General Public License, |
| 8 | * version 2, as published by the Free Software Foundation. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | */ |
| 15 | |
| 16 | /* |
| 17 | * The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors |
| 18 | * are i2c devices which have an identical programming interface for |
| 19 | * measuring relative humidity and temperature. The Si7013 has an additional |
| 20 | * temperature input which this driver does not support. |
| 21 | * |
| 22 | * Data Sheets: |
| 23 | * Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf |
| 24 | * Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf |
| 25 | * Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf |
| 26 | */ |
| 27 | |
| 28 | #include <linux/delay.h> |
| 29 | #include <linux/i2c.h> |
| 30 | #include <linux/module.h> |
| 31 | #include <linux/slab.h> |
| 32 | #include <linux/sysfs.h> |
| 33 | |
| 34 | #include <linux/iio/iio.h> |
| 35 | #include <linux/iio/sysfs.h> |
| 36 | |
| 37 | /* Measure Relative Humidity, Hold Master Mode */ |
| 38 | #define SI7020CMD_RH_HOLD 0xE5 |
| 39 | /* Measure Temperature, Hold Master Mode */ |
| 40 | #define SI7020CMD_TEMP_HOLD 0xE3 |
| 41 | /* Software Reset */ |
| 42 | #define SI7020CMD_RESET 0xFE |
| 43 | |
| 44 | static int si7020_read_raw(struct iio_dev *indio_dev, |
| 45 | struct iio_chan_spec const *chan, int *val, |
| 46 | int *val2, long mask) |
| 47 | { |
Jonathan Cameron | e765537 | 2015-02-14 11:32:17 +0000 | [diff] [blame] | 48 | struct i2c_client **client = iio_priv(indio_dev); |
David Barksdale | 064a746 | 2014-09-29 13:28:55 -0500 | [diff] [blame] | 49 | int ret; |
| 50 | |
| 51 | switch (mask) { |
| 52 | case IIO_CHAN_INFO_RAW: |
Jonathan Cameron | e765537 | 2015-02-14 11:32:17 +0000 | [diff] [blame] | 53 | ret = i2c_smbus_read_word_data(*client, |
David Barksdale | 064a746 | 2014-09-29 13:28:55 -0500 | [diff] [blame] | 54 | chan->type == IIO_TEMP ? |
| 55 | SI7020CMD_TEMP_HOLD : |
| 56 | SI7020CMD_RH_HOLD); |
| 57 | if (ret < 0) |
| 58 | return ret; |
Hartmut Knaack | 345b483 | 2014-10-25 20:09:11 +0200 | [diff] [blame] | 59 | *val = ret >> 2; |
| 60 | if (chan->type == IIO_HUMIDITYRELATIVE) |
| 61 | *val &= GENMASK(11, 0); |
David Barksdale | 064a746 | 2014-09-29 13:28:55 -0500 | [diff] [blame] | 62 | return IIO_VAL_INT; |
| 63 | case IIO_CHAN_INFO_SCALE: |
| 64 | if (chan->type == IIO_TEMP) |
| 65 | *val = 175720; /* = 175.72 * 1000 */ |
| 66 | else |
| 67 | *val = 125 * 1000; |
| 68 | *val2 = 65536 >> 2; |
| 69 | return IIO_VAL_FRACTIONAL; |
| 70 | case IIO_CHAN_INFO_OFFSET: |
| 71 | /* |
| 72 | * Since iio_convert_raw_to_processed_unlocked assumes offset |
| 73 | * is an integer we have to round these values and lose |
| 74 | * accuracy. |
| 75 | * Relative humidity will be 0.0032959% too high and |
| 76 | * temperature will be 0.00277344 degrees too high. |
| 77 | * This is no big deal because it's within the accuracy of the |
| 78 | * sensor. |
| 79 | */ |
| 80 | if (chan->type == IIO_TEMP) |
| 81 | *val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */ |
| 82 | else |
| 83 | *val = -786; /* = -6 * (65536 >> 2) / 125 */ |
| 84 | return IIO_VAL_INT; |
| 85 | default: |
| 86 | break; |
| 87 | } |
| 88 | |
| 89 | return -EINVAL; |
| 90 | } |
| 91 | |
| 92 | static const struct iio_chan_spec si7020_channels[] = { |
| 93 | { |
| 94 | .type = IIO_HUMIDITYRELATIVE, |
| 95 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | |
| 96 | BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), |
| 97 | }, |
| 98 | { |
| 99 | .type = IIO_TEMP, |
| 100 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | |
| 101 | BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), |
| 102 | } |
| 103 | }; |
| 104 | |
| 105 | static const struct iio_info si7020_info = { |
| 106 | .read_raw = si7020_read_raw, |
| 107 | .driver_module = THIS_MODULE, |
| 108 | }; |
| 109 | |
| 110 | static int si7020_probe(struct i2c_client *client, |
| 111 | const struct i2c_device_id *id) |
| 112 | { |
| 113 | struct iio_dev *indio_dev; |
| 114 | struct i2c_client **data; |
| 115 | int ret; |
| 116 | |
| 117 | if (!i2c_check_functionality(client->adapter, |
| 118 | I2C_FUNC_SMBUS_WRITE_BYTE | |
| 119 | I2C_FUNC_SMBUS_READ_WORD_DATA)) |
| 120 | return -ENODEV; |
| 121 | |
| 122 | /* Reset device, loads default settings. */ |
| 123 | ret = i2c_smbus_write_byte(client, SI7020CMD_RESET); |
| 124 | if (ret < 0) |
| 125 | return ret; |
| 126 | /* Wait the maximum power-up time after software reset. */ |
| 127 | msleep(15); |
| 128 | |
Andrey Smirnov | e01becb | 2015-02-12 23:58:41 -0800 | [diff] [blame] | 129 | indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); |
David Barksdale | 064a746 | 2014-09-29 13:28:55 -0500 | [diff] [blame] | 130 | if (!indio_dev) |
| 131 | return -ENOMEM; |
| 132 | |
| 133 | data = iio_priv(indio_dev); |
| 134 | *data = client; |
David Barksdale | 064a746 | 2014-09-29 13:28:55 -0500 | [diff] [blame] | 135 | |
| 136 | indio_dev->dev.parent = &client->dev; |
| 137 | indio_dev->name = dev_name(&client->dev); |
| 138 | indio_dev->modes = INDIO_DIRECT_MODE; |
| 139 | indio_dev->info = &si7020_info; |
| 140 | indio_dev->channels = si7020_channels; |
| 141 | indio_dev->num_channels = ARRAY_SIZE(si7020_channels); |
| 142 | |
| 143 | return devm_iio_device_register(&client->dev, indio_dev); |
| 144 | } |
| 145 | |
| 146 | static const struct i2c_device_id si7020_id[] = { |
| 147 | { "si7020", 0 }, |
| 148 | { } |
| 149 | }; |
| 150 | MODULE_DEVICE_TABLE(i2c, si7020_id); |
| 151 | |
| 152 | static struct i2c_driver si7020_driver = { |
| 153 | .driver.name = "si7020", |
| 154 | .probe = si7020_probe, |
| 155 | .id_table = si7020_id, |
| 156 | }; |
| 157 | |
| 158 | module_i2c_driver(si7020_driver); |
| 159 | MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors"); |
| 160 | MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>"); |
| 161 | MODULE_LICENSE("GPL"); |