--- /dev/null
+/*
+ * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
+ * Copyright (c) 2013,2014 Uplogix, Inc.
+ * David Barksdale <dbarksdale@uplogix.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+/*
+ * The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors
+ * are i2c devices which have an identical programming interface for
+ * measuring relative humidity and temperature. The Si7013 has an additional
+ * temperature input which this driver does not support.
+ *
+ * Data Sheets:
+ * Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf
+ * Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf
+ * Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf
+ */
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+/* Measure Relative Humidity, Hold Master Mode */
+#define SI7020CMD_RH_HOLD 0xE5
+/* Measure Temperature, Hold Master Mode */
+#define SI7020CMD_TEMP_HOLD 0xE3
+/* Software Reset */
+#define SI7020CMD_RESET 0xFE
+
+static int si7020_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int *val,
+ int *val2, long mask)
+{
+ struct i2c_client **client = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ ret = i2c_smbus_read_word_data(*client,
+ chan->type == IIO_TEMP ?
+ SI7020CMD_TEMP_HOLD :
+ SI7020CMD_RH_HOLD);
+ if (ret < 0)
+ return ret;
+ *val = ret >> 2;
+ if (chan->type == IIO_HUMIDITYRELATIVE)
+ *val &= GENMASK(11, 0);
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ if (chan->type == IIO_TEMP)
+ *val = 175720; /* = 175.72 * 1000 */
+ else
+ *val = 125 * 1000;
+ *val2 = 65536 >> 2;
+ return IIO_VAL_FRACTIONAL;
+ case IIO_CHAN_INFO_OFFSET:
+ /*
+ * Since iio_convert_raw_to_processed_unlocked assumes offset
+ * is an integer we have to round these values and lose
+ * accuracy.
+ * Relative humidity will be 0.0032959% too high and
+ * temperature will be 0.00277344 degrees too high.
+ * This is no big deal because it's within the accuracy of the
+ * sensor.
+ */
+ if (chan->type == IIO_TEMP)
+ *val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */
+ else
+ *val = -786; /* = -6 * (65536 >> 2) / 125 */
+ return IIO_VAL_INT;
+ default:
+ break;
+ }
+
+ return -EINVAL;
+}
+
+static const struct iio_chan_spec si7020_channels[] = {
+ {
+ .type = IIO_HUMIDITYRELATIVE,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
+ },
+ {
+ .type = IIO_TEMP,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
+ }
+};
+
+static const struct iio_info si7020_info = {
+ .read_raw = si7020_read_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static int si7020_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct iio_dev *indio_dev;
+ struct i2c_client **data;
+ int ret;
+
+ if (!i2c_check_functionality(client->adapter,
+ I2C_FUNC_SMBUS_WRITE_BYTE |
+ I2C_FUNC_SMBUS_READ_WORD_DATA))
+ return -ENODEV;
+
+ /* Reset device, loads default settings. */
+ ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
+ if (ret < 0)
+ return ret;
+ /* Wait the maximum power-up time after software reset. */
+ msleep(15);
+
+ indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ data = iio_priv(indio_dev);
+ *data = client;
+
+ indio_dev->dev.parent = &client->dev;
+ indio_dev->name = dev_name(&client->dev);
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->info = &si7020_info;
+ indio_dev->channels = si7020_channels;
+ indio_dev->num_channels = ARRAY_SIZE(si7020_channels);
+
+ return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id si7020_id[] = {
+ { "si7020", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, si7020_id);
+
+static struct i2c_driver si7020_driver = {
+ .driver.name = "si7020",
+ .probe = si7020_probe,
+ .id_table = si7020_id,
+};
+
+module_i2c_driver(si7020_driver);
+MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors");
+MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff