drivers/hwmon/shtc1.c - kernel/quantenna - Git at Google

 /* Sensirion SHTC1 humidity and temperature sensor driver
  *
  * Copyright (C) 2014 Sensirion AG, Switzerland
  * Author: Johannes Winkelmann <johannes.winkelmann@sensirion.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * 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.
  *
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
 #include <linux/delay.h>
 #include <linux/platform_data/shtc1.h>

 /* commands (high precision mode) */
 static const unsigned char shtc1_cmd_measure_blocking_hpm[]    = { 0x7C, 0xA2 };
 static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };

 /* commands (low precision mode) */
 static const unsigned char shtc1_cmd_measure_blocking_lpm[]    = { 0x64, 0x58 };
 static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c };

 /* command for reading the ID register */
 static const unsigned char shtc1_cmd_read_id_reg[]	       = { 0xef, 0xc8 };

 /* constants for reading the ID register */
 #define SHTC1_ID	  0x07
 #define SHTC1_ID_REG_MASK 0x1f

 /* delays for non-blocking i2c commands, both in us */
 #define SHTC1_NONBLOCKING_WAIT_TIME_HPM  14400
 #define SHTC1_NONBLOCKING_WAIT_TIME_LPM   1000

 #define SHTC1_CMD_LENGTH      2
 #define SHTC1_RESPONSE_LENGTH 6

 struct shtc1_data {
 	struct i2c_client *client;
 	struct mutex update_lock;
 	bool valid;
 	unsigned long last_updated; /* in jiffies */

 	const unsigned char *command;
 	unsigned int nonblocking_wait_time; /* in us */

 	struct shtc1_platform_data setup;

 	int temperature; /* 1000 * temperature in dgr C */
 	int humidity; /* 1000 * relative humidity in %RH */
 };

 static int shtc1_update_values(struct i2c_client *client,
 			       struct shtc1_data *data,
 			       char *buf, int bufsize)
 {
 	int ret = i2c_master_send(client, data->command, SHTC1_CMD_LENGTH);
 	if (ret != SHTC1_CMD_LENGTH) {
 		dev_err(&client->dev, "failed to send command: %d\n", ret);
 		return ret < 0 ? ret : -EIO;
 	}

 	/*
 	 * In blocking mode (clock stretching mode) the I2C bus
 	 * is blocked for other traffic, thus the call to i2c_master_recv()
 	 * will wait until the data is ready. For non blocking mode, we
 	 * have to wait ourselves.
 	 */
 	if (!data->setup.blocking_io)
 		usleep_range(data->nonblocking_wait_time,
 			     data->nonblocking_wait_time + 1000);

 	ret = i2c_master_recv(client, buf, bufsize);
 	if (ret != bufsize) {
 		dev_err(&client->dev, "failed to read values: %d\n", ret);
 		return ret < 0 ? ret : -EIO;
 	}

 	return 0;
 }

 /* sysfs attributes */
 static struct shtc1_data *shtc1_update_client(struct device *dev)
 {
 	struct shtc1_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	unsigned char buf[SHTC1_RESPONSE_LENGTH];
 	int val;
 	int ret = 0;

 	mutex_lock(&data->update_lock);

 	if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
 		ret = shtc1_update_values(client, data, buf, sizeof(buf));
 		if (ret)
 			goto out;

 		/*
 		 * From datasheet:
 		 * T = -45 + 175 * ST / 2^16
 		 * RH = 100 * SRH / 2^16
 		 *
 		 * Adapted for integer fixed point (3 digit) arithmetic.
 		 */
 		val = be16_to_cpup((__be16 *)buf);
 		data->temperature = ((21875 * val) >> 13) - 45000;
 		val = be16_to_cpup((__be16 *)(buf + 3));
 		data->humidity = ((12500 * val) >> 13);

 		data->last_updated = jiffies;
 		data->valid = true;
 	}

 out:
 	mutex_unlock(&data->update_lock);

 	return ret == 0 ? data : ERR_PTR(ret);
 }

 static ssize_t temp1_input_show(struct device *dev,
 				struct device_attribute *attr,
 				char *buf)
 {
 	struct shtc1_data *data = shtc1_update_client(dev);
 	if (IS_ERR(data))
 		return PTR_ERR(data);

 	return sprintf(buf, "%d\n", data->temperature);
 }

 static ssize_t humidity1_input_show(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
 	struct shtc1_data *data = shtc1_update_client(dev);
 	if (IS_ERR(data))
 		return PTR_ERR(data);

 	return sprintf(buf, "%d\n", data->humidity);
 }

 static DEVICE_ATTR_RO(temp1_input);
 static DEVICE_ATTR_RO(humidity1_input);

 static struct attribute *shtc1_attrs[] = {
 	&dev_attr_temp1_input.attr,
 	&dev_attr_humidity1_input.attr,
 	NULL
 };

 ATTRIBUTE_GROUPS(shtc1);

 static void shtc1_select_command(struct shtc1_data *data)
 {
 	if (data->setup.high_precision) {
 		data->command = data->setup.blocking_io ?
 				shtc1_cmd_measure_blocking_hpm :
 				shtc1_cmd_measure_nonblocking_hpm;
 		data->nonblocking_wait_time = SHTC1_NONBLOCKING_WAIT_TIME_HPM;

 	} else {
 		data->command = data->setup.blocking_io ?
 				shtc1_cmd_measure_blocking_lpm :
 				shtc1_cmd_measure_nonblocking_lpm;
 		data->nonblocking_wait_time = SHTC1_NONBLOCKING_WAIT_TIME_LPM;
 	}
 }

 static int shtc1_probe(struct i2c_client *client,
 		       const struct i2c_device_id *id)
 {
 	int ret;
 	char id_reg[2];
 	struct shtc1_data *data;
 	struct device *hwmon_dev;
 	struct i2c_adapter *adap = client->adapter;
 	struct device *dev = &client->dev;

 	if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
 		dev_err(dev, "plain i2c transactions not supported\n");
 		return -ENODEV;
 	}

 	ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
 	if (ret != SHTC1_CMD_LENGTH) {
 		dev_err(dev, "could not send read_id_reg command: %d\n", ret);
 		return ret < 0 ? ret : -ENODEV;
 	}
 	ret = i2c_master_recv(client, id_reg, sizeof(id_reg));
 	if (ret != sizeof(id_reg)) {
 		dev_err(dev, "could not read ID register: %d\n", ret);
 		return -ENODEV;
 	}
 	if ((id_reg[1] & SHTC1_ID_REG_MASK) != SHTC1_ID) {
 		dev_err(dev, "ID register doesn't match\n");
 		return -ENODEV;
 	}

 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->setup.blocking_io = false;
 	data->setup.high_precision = true;
 	data->client = client;

 	if (client->dev.platform_data)
 		data->setup = *(struct shtc1_platform_data *)dev->platform_data;
 	shtc1_select_command(data);
 	mutex_init(&data->update_lock);

 	hwmon_dev = devm_hwmon_device_register_with_groups(dev,
 							   client->name,
 							   data,
 							   shtc1_groups);
 	if (IS_ERR(hwmon_dev))
 		dev_dbg(dev, "unable to register hwmon device\n");

 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 /* device ID table */
 static const struct i2c_device_id shtc1_id[] = {
 	{ "shtc1", 0 },
 	{ "shtw1", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, shtc1_id);

 static struct i2c_driver shtc1_i2c_driver = {
 	.driver.name  = "shtc1",
 	.probe        = shtc1_probe,
 	.id_table     = shtc1_id,
 };

 module_i2c_driver(shtc1_i2c_driver);

 MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>");
 MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
 MODULE_LICENSE("GPL");
	/* Sensirion SHTC1 humidity and temperature sensor driver
	*
	* Copyright (C) 2014 Sensirion AG, Switzerland
	* Author: Johannes Winkelmann <johannes.winkelmann@sensirion.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* 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.
	*
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/i2c.h>
	#include <linux/hwmon.h>
	#include <linux/hwmon-sysfs.h>
	#include <linux/err.h>
	#include <linux/delay.h>
	#include <linux/platform_data/shtc1.h>

	/* commands (high precision mode) */
	static const unsigned char shtc1_cmd_measure_blocking_hpm[] = { 0x7C, 0xA2 };
	static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };

	/* commands (low precision mode) */
	static const unsigned char shtc1_cmd_measure_blocking_lpm[] = { 0x64, 0x58 };
	static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c };

	/* command for reading the ID register */
	static const unsigned char shtc1_cmd_read_id_reg[] = { 0xef, 0xc8 };

	/* constants for reading the ID register */
	#define SHTC1_ID 0x07
	#define SHTC1_ID_REG_MASK 0x1f

	/* delays for non-blocking i2c commands, both in us */
	#define SHTC1_NONBLOCKING_WAIT_TIME_HPM 14400
	#define SHTC1_NONBLOCKING_WAIT_TIME_LPM 1000

	#define SHTC1_CMD_LENGTH 2
	#define SHTC1_RESPONSE_LENGTH 6

	struct shtc1_data {
	struct i2c_client *client;
	struct mutex update_lock;
	bool valid;
	unsigned long last_updated; /* in jiffies */

	const unsigned char *command;
	unsigned int nonblocking_wait_time; /* in us */

	struct shtc1_platform_data setup;

	int temperature; /* 1000 * temperature in dgr C */
	int humidity; /* 1000 * relative humidity in %RH */
	};

	static int shtc1_update_values(struct i2c_client *client,
	struct shtc1_data *data,
	char *buf, int bufsize)
	{
	int ret = i2c_master_send(client, data->command, SHTC1_CMD_LENGTH);
	if (ret != SHTC1_CMD_LENGTH) {
	dev_err(&client->dev, "failed to send command: %d\n", ret);
	return ret < 0 ? ret : -EIO;
	}

	/*
	* In blocking mode (clock stretching mode) the I2C bus
	* is blocked for other traffic, thus the call to i2c_master_recv()
	* will wait until the data is ready. For non blocking mode, we
	* have to wait ourselves.
	*/
	if (!data->setup.blocking_io)
	usleep_range(data->nonblocking_wait_time,
	data->nonblocking_wait_time + 1000);

	ret = i2c_master_recv(client, buf, bufsize);
	if (ret != bufsize) {
	dev_err(&client->dev, "failed to read values: %d\n", ret);
	return ret < 0 ? ret : -EIO;
	}

	return 0;
	}

	/* sysfs attributes */
	static struct shtc1_data shtc1_update_client(struct device dev)
	{
	struct shtc1_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	unsigned char buf[SHTC1_RESPONSE_LENGTH];
	int val;
	int ret = 0;

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + HZ / 10) \|\| !data->valid) {
	ret = shtc1_update_values(client, data, buf, sizeof(buf));
	if (ret)
	goto out;

	/*
	* From datasheet:
	* T = -45 + 175 * ST / 2^16
	* RH = 100 * SRH / 2^16
	*
	* Adapted for integer fixed point (3 digit) arithmetic.
	*/
	val = be16_to_cpup((__be16 *)buf);
	data->temperature = ((21875 * val) >> 13) - 45000;
	val = be16_to_cpup((__be16 *)(buf + 3));
	data->humidity = ((12500 * val) >> 13);

	data->last_updated = jiffies;
	data->valid = true;
	}

	out:
	mutex_unlock(&data->update_lock);

	return ret == 0 ? data : ERR_PTR(ret);
	}

	static ssize_t temp1_input_show(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	struct shtc1_data *data = shtc1_update_client(dev);
	if (IS_ERR(data))
	return PTR_ERR(data);

	return sprintf(buf, "%d\n", data->temperature);
	}

	static ssize_t humidity1_input_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct shtc1_data *data = shtc1_update_client(dev);
	if (IS_ERR(data))
	return PTR_ERR(data);

	return sprintf(buf, "%d\n", data->humidity);
	}

	static DEVICE_ATTR_RO(temp1_input);
	static DEVICE_ATTR_RO(humidity1_input);

	static struct attribute *shtc1_attrs[] = {
	&dev_attr_temp1_input.attr,
	&dev_attr_humidity1_input.attr,
	NULL
	};

	ATTRIBUTE_GROUPS(shtc1);

	static void shtc1_select_command(struct shtc1_data *data)
	{
	if (data->setup.high_precision) {
	data->command = data->setup.blocking_io ?
	shtc1_cmd_measure_blocking_hpm :
	shtc1_cmd_measure_nonblocking_hpm;
	data->nonblocking_wait_time = SHTC1_NONBLOCKING_WAIT_TIME_HPM;

	} else {
	data->command = data->setup.blocking_io ?
	shtc1_cmd_measure_blocking_lpm :
	shtc1_cmd_measure_nonblocking_lpm;
	data->nonblocking_wait_time = SHTC1_NONBLOCKING_WAIT_TIME_LPM;
	}
	}

	static int shtc1_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	int ret;
	char id_reg[2];
	struct shtc1_data *data;
	struct device *hwmon_dev;
	struct i2c_adapter *adap = client->adapter;
	struct device *dev = &client->dev;

	if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
	dev_err(dev, "plain i2c transactions not supported\n");
	return -ENODEV;
	}

	ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
	if (ret != SHTC1_CMD_LENGTH) {
	dev_err(dev, "could not send read_id_reg command: %d\n", ret);
	return ret < 0 ? ret : -ENODEV;
	}
	ret = i2c_master_recv(client, id_reg, sizeof(id_reg));
	if (ret != sizeof(id_reg)) {
	dev_err(dev, "could not read ID register: %d\n", ret);
	return -ENODEV;
	}
	if ((id_reg[1] & SHTC1_ID_REG_MASK) != SHTC1_ID) {
	dev_err(dev, "ID register doesn't match\n");
	return -ENODEV;
	}

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->setup.blocking_io = false;
	data->setup.high_precision = true;
	data->client = client;

	if (client->dev.platform_data)
	data->setup = (struct shtc1_platform_data )dev->platform_data;
	shtc1_select_command(data);
	mutex_init(&data->update_lock);

	hwmon_dev = devm_hwmon_device_register_with_groups(dev,
	client->name,
	data,
	shtc1_groups);
	if (IS_ERR(hwmon_dev))
	dev_dbg(dev, "unable to register hwmon device\n");

	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	/* device ID table */
	static const struct i2c_device_id shtc1_id[] = {
	{ "shtc1", 0 },
	{ "shtw1", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, shtc1_id);

	static struct i2c_driver shtc1_i2c_driver = {
	.driver.name = "shtc1",
	.probe = shtc1_probe,
	.id_table = shtc1_id,
	};

	module_i2c_driver(shtc1_i2c_driver);

	MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>");
	MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
	MODULE_LICENSE("GPL");