Fist commit

.gitignore

+# Prerequisites
+*.d
+
+# Object files
+*.o
+*.ko
+*.obj
+*.elf
+
+# Linker output
+*.ilk
+*.map
+*.exp
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Libraries
+*.lib
+*.a
+*.la
+*.lo
+
+# Shared objects (inc. Windows DLLs)
+*.dll
+*.so
+*.so.*
+*.dylib
+
+# Executables
+*.exe
+*.out
+*.app
+*.i*86
+*.x86_64
+*.hex
+
+# Debug files
+*.dSYM/
+*.su
+*.idb
+*.pdb
+
+# Kernel Module Compile Results
+*.mod*
+*.cmd
+.tmp_versions/
+modules.order
+Module.symvers
+Mkfile.old
+
+# Swap
+[._]*.s[a-v][a-z]
+[._]*.sw[a-p]
+[._]s[a-v][a-z]
+[._]sw[a-p]
+
+# Session
+Session.vim
+
+# Temporary
+.netrwhist
+*~
+# Auto-generated tag files
+tags
+

Makefile

+obj-m += si7020.o
+
+all:
+	$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+	$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
+

README.md

+Out of tree module for the si7020 humidity+temperature sensor
+this is a temporary fix until corna upstreams the non-blocking wait mode

si7020.c

+/*
+ * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
+ * Copyright (c) 2013,2014  Uplogix, Inc.
+ * David Barksdale <dbarksdale@uplogix.com>
+ * Copyright (c) 2015 Nicola Corna <nicola@corna.info>
+ *
+ * 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/jiffies.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include "si7020.h"
+
+/* Measure Relative Humidity, Hold Master Mode */
+#define SI7020CMD_RH_HOLD	0xE5
+/* Measure Relative Humidity, No Hold Master Mode */
+#define SI7020CMD_RH_NO_HOLD	0xF5
+/* Measure Temperature, Hold Master Mode */
+#define SI7020CMD_TEMP_HOLD	0xE3
+/* Measure Temperature, No Hold Master Mode */
+#define SI7020CMD_TEMP_NO_HOLD	0xF3
+/* Software Reset */
+#define SI7020CMD_RESET		0xFE
+/* Relative humidity measurement timeout (us) */
+#define SI7020_RH_TIMEOUT	22800
+/* Temperature measurement timeout (us) */
+#define SI7020_TEMP_TIMEOUT	10800
+/* Minimum delay between retries (No Hold Mode) in us */
+#define SI7020_NOHOLD_SLEEP_MIN	2000
+/* Maximum delay between retries (No Hold Mode) in us */
+#define SI7020_NOHOLD_SLEEP_MAX	6000
+
+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);
+	struct si7020_platform_data *pdata;
+	int ret;
+	bool holdmode;
+	unsigned char buf[2];
+	unsigned long start;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		pdata = dev_get_platdata(&(*client)->dev);
+		if (pdata)
+			holdmode = pdata->blocking_io;
+		else
+			holdmode = !i2c_check_quirks((*client)->adapter,
+				   I2C_AQ_NO_CLK_STRETCH);
+		if (holdmode) {
+			ret = i2c_smbus_read_word_swapped(*client,
+						  chan->type == IIO_TEMP ?
+						  SI7020CMD_TEMP_HOLD :
+						  SI7020CMD_RH_HOLD);
+			if (ret < 0)
+				return ret;
+			*val = ret >> 2;
+		} else {
+			ret = i2c_smbus_write_byte(*client,
+						   chan->type == IIO_TEMP ?
+						   SI7020CMD_TEMP_NO_HOLD :
+						   SI7020CMD_RH_NO_HOLD);
+			if (ret < 0)
+				return ret;
+			start = jiffies;
+			while ((ret = i2c_master_recv(*client, buf, 2)) < 0) {
+				if (time_after(jiffies, start +
+					       usecs_to_jiffies(
+							chan->type == IIO_TEMP ?
+							SI7020_TEMP_TIMEOUT :
+							SI7020_RH_TIMEOUT)))
+					return ret;
+				usleep_range(SI7020_NOHOLD_SLEEP_MIN,
+					     SI7020_NOHOLD_SLEEP_MAX);
+			}
+			*val = ((buf[0] << 8) | buf[1]) >> 2;
+		}
+		/*
+		 * Humidity values can slightly exceed the 0-100%RH
+		 * range and should be corrected by software
+		 */
+		if (chan->type == IIO_HUMIDITYRELATIVE)
+			*val = clamp_val(*val, 786, 13893);
+		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;
+	struct si7020_platform_data *pdata;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_WRITE_BYTE |
+				     I2C_FUNC_SMBUS_READ_WORD_DATA))
+		return -ENODEV;
+
+	pdata = dev_get_platdata(&client->dev);
+	if (pdata) {
+		if (pdata->blocking_io) {
+			if (i2c_check_quirks(client->adapter,
+			   I2C_AQ_NO_CLK_STRETCH))
+				return -ENODEV;
+		} else if (!i2c_check_functionality(client->adapter,
+			  I2C_FUNC_I2C))
+			return -ENODEV;
+	} else
+		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C) &&
+		   i2c_check_quirks(client->adapter, I2C_AQ_NO_CLK_STRETCH))
+			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");

si7020.h

+/*
+ * Copyright (C) 2015 Nicola Corna <nicola@corna.info>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#ifndef __SI7020_H_
+#define __SI7020_H_
+
+struct si7020_platform_data {
+	bool blocking_io;
+};
+#endif /* __SI7020_H_ */