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Date: Thu, 01 May 2014 16:05:30 -0700
From: Tomas Pop <tomas.pop.mff@...il.com>
To: "jdelvare@...e.de" <jdelvare@...e.de>
Cc: "linux@...ck-us.net" <linux@...ck-us.net>,
lm-sensors@...sensors.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [RFC][PATCH v2] hwmon: add support for Sensirion SHTC1 sensor
One more time this patch sent with correct settings of my email client
- I'm sorry for this.
This is a second version of the driver for Sensirion SHTC1 humidity and
temperature sensor. Initial version was submitted in July 2012.
http://www.gossamer-threads.com/lists/linux/kernel/1569130#1569130
We included suggested corrections formerly discussed in this list after
initial submission, but since it is quite a while, we are re-submitting
it again as a request for comments. Here is a list of important changes
to the initial version:
* returning real error codes instead of -1 or -ENODEV
* using boolean variables instead of bitmaps where possible
* macros be16_to_cpup used for conversion of indianneess
* corrected formula for decoding of humidity and temperature values
* documentation update
Patch was generated against kernel v3.15-rc3
Signed-off-by: Tomas Pop <tomas.pop@...sirion.com>
---
Documentation/hwmon/shtc1 | 38 +++++
drivers/hwmon/Kconfig | 10 ++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/shtc1.c | 323 ++++++++++++++++++++++++++++++++++++
include/linux/platform_data/shtc1.h | 24 +++
5 files changed, 396 insertions(+)
create mode 100644 Documentation/hwmon/shtc1
create mode 100644 drivers/hwmon/shtc1.c
create mode 100644 include/linux/platform_data/shtc1.h
diff --git a/Documentation/hwmon/shtc1 b/Documentation/hwmon/shtc1
new file mode 100644
index 0000000..6a72ae2d
--- /dev/null
+++ b/Documentation/hwmon/shtc1
@@ -0,0 +1,38 @@
+Kernel driver shtc1
+===================
+
+Supported chips:
+ * Sensirion SHTC1
+ Prefix: 'shtc1'
+ Addresses scanned: none
+ Datasheet: Publicly available at the Sensirion website
+ http://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/Humidity/Sensirion_Humidity_SHTC1_Datasheet.pdf
+
+Author:
+ Johannes Winkelmann <johannes.winkelmann@...sirion.com>
+
+Description
+-----------
+
+This driver implements support for the Sensirion SHTC1 chip, a humidity and
+temperature sensor. Temperature is measured in degrees celsius, relative
+humidity is expressed as a percentage. Driver can be used as well for SHTW1
+chip, that has the same electrical interface, but datasheet has not been
+yet published.
+
+The device communicates with the I2C protocol. All sensors are set to the same
+I2C address 0x70, so an entry with I2C_BOARD_INFO("shtc1", 0x70) can be used
+in the board setup code. See Documentation/i2c/instantiating-devices for
+other methods to instantiate the device.
+
+Furthermore, there are two configuration options by means of platform_data:
+1. blocking (pull the I2C clock line down while performing the measurement) or
+ non-blocking, mode. Blocking mode will guarantee the fastest result, but
+ the I2C bus will be busy during that time
+2. high or low accuracy. Using high accuracy is always recommended.
+
+sysfs-Interface
+---------------
+
+temp1_input - temperature input
+humidity1_input - humidity input
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index bc196f4..4d58149 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1114,6 +1114,16 @@ config SENSORS_SHT21
This driver can also be built as a module. If so, the module
will be called sht21.
+config SENSORS_SHTC1
+ tristate "Sensiron humidity and temperature sensors. SHTC1 and compat."
+ depends on I2C
+ help
+ If you say yes here you get support for the Sensiron SHTC1 humidity
+ and temperature sensor.
+
+ This driver can also be built as a module. If so, the module
+ will be called shtc1.
+
config SENSORS_S3C
tristate "Samsung built-in ADC"
depends on S3C_ADC
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index c48f987..1cc5273 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -125,6 +125,7 @@ obj-$(CONFIG_SENSORS_SCH5627) += sch5627.o
obj-$(CONFIG_SENSORS_SCH5636) += sch5636.o
obj-$(CONFIG_SENSORS_SHT15) += sht15.o
obj-$(CONFIG_SENSORS_SHT21) += sht21.o
+obj-$(CONFIG_SENSORS_SHTC1) += shtc1.o
obj-$(CONFIG_SENSORS_SIS5595) += sis5595.o
obj-$(CONFIG_SENSORS_SMM665) += smm665.o
obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
diff --git a/drivers/hwmon/shtc1.c b/drivers/hwmon/shtc1.c
new file mode 100644
index 0000000..96d398b
--- /dev/null
+++ b/drivers/hwmon/shtc1.c
@@ -0,0 +1,323 @@
+/* Sensirion SHTC1 humidity and temperature sensor driver
+ *
+ * Copyright (C) 2012 Sensirion AG, Switzerland
+ * Author: Johannes Winkelmann <johannes.winkelmann@...sirion.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.
+ *
+ * Data sheet available soon
+ * TODO: add link
+ */
+
+#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 and constants for reading the ID register */
+static const unsigned char shtc1_cmd_read_id_reg[] = { 0xef, 0xc8 };
+static const unsigned char shtc1_id_reg_content = 0x07;
+static const unsigned char shtc1_id_reg_mask = 0x1f;
+
+/* delays for non-blocking i2c commands */
+/* TODO: use max timings */
+#define SHTC1_NONBLOCKING_WAIT_TIME_HPM 10
+#define SHTC1_NONBLOCKING_WAIT_TIME_LPM 1
+
+#define SHTC1_CMD_LENGTH 2
+#define SHTC1_RESPONSE_LENGTH 6
+
+struct shtc1_data {
+ struct device *hwmon_dev;
+ struct mutex update_lock;
+ bool valid;
+ unsigned long last_updated; /* In jiffies */
+
+ const unsigned char *command;
+ unsigned int nonblocking_wait_time;
+
+ struct shtc1_platform_data setup;
+
+ int temperature;
+ int humidity;
+};
+
+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_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 < 0) {
+ dev_err(&client->dev, "failed to send command: %d", ret);
+ return ret;
+ }
+
+ /*
+ * 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, thus the msleep().
+ *
+ * TODO: consider usleep_range
+ */
+ if (!data->setup.blocking_io)
+ msleep(data->nonblocking_wait_time);
+
+ ret = i2c_master_recv(client, buf, bufsize);
+ if (ret != bufsize) {
+ dev_err(&client->dev, "failed to read values: %d", ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+/* sysfs attributes */
+static struct shtc1_data *shtc1_update_client(struct device *dev)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct shtc1_data *data = i2c_get_clientdata(client);
+
+ unsigned char buf[SHTC1_RESPONSE_LENGTH];
+ int val;
+ int ret;
+
+ mutex_lock(&data->update_lock);
+
+ /*
+ * Initialize 'ret' in case we had a valid result before, but
+ * read too quickly in which case we return the last values.
+ */
+ ret = !data->valid;
+
+ 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 = 1;
+ }
+
+out:
+ mutex_unlock(&data->update_lock);
+
+ return ret == 0 ? data : ERR_PTR(ret);
+}
+
+static ssize_t shtc1_show_temperature(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 shtc1_show_humidity(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 SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
+ shtc1_show_temperature, NULL, 0);
+static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO,
+ shtc1_show_humidity, NULL, 0);
+
+static struct attribute *shtc1_attributes[] = {
+ &sensor_dev_attr_temp1_input.dev_attr.attr,
+ &sensor_dev_attr_humidity1_input.dev_attr.attr,
+ NULL
+};
+
+static const struct attribute_group shtc1_attr_group = {
+ .attrs = shtc1_attributes,
+};
+
+static int shtc1_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct shtc1_data *data;
+ int err;
+ struct i2c_adapter *adap = client->adapter;
+ char id_reg[2];
+
+ if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
+ dev_err(&client->dev,
+ "adapter does not support plain i2c transactions\n");
+ return -ENODEV;
+ }
+
+ err = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
+
+ if (err < 0) {
+ dev_err(&client->dev, "could not send read command: %d\n", err);
+ return -ENODEV;
+ }
+ err = i2c_master_recv(client, id_reg, sizeof(id_reg));
+ if (err != sizeof(id_reg)) {
+ dev_err(&client->dev, "could not read ID register: %d\n", err);
+ return -ENODEV;
+ }
+ if ((id_reg[1] & shtc1_id_reg_mask) != shtc1_id_reg_content) {
+ dev_err(&client->dev, "ID register doesn't match\n");
+ return -ENODEV;
+ }
+
+ data = devm_kzalloc(&client->dev, sizeof(struct shtc1_data),
+ GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ /* defaults: blocking, high precision mode */
+ data->setup.blocking_io = 1;
+ data->setup.high_precision = 1;
+
+ if (client->dev.platform_data)
+ data->setup = *(struct shtc1_platform_data *)client->dev.platform_data;
+ shtc1_select_command(data);
+
+ i2c_set_clientdata(client, data);
+ mutex_init(&data->update_lock);
+
+ err = sysfs_create_group(&client->dev.kobj, &shtc1_attr_group);
+ if (err) {
+ dev_dbg(&client->dev, "could not create sysfs files\n");
+ goto fail_free;
+ return err;
+ }
+ data->hwmon_dev = hwmon_device_register(&client->dev);
+ if (IS_ERR(data->hwmon_dev)) {
+ dev_dbg(&client->dev, "unable to register hwmon device\n");
+ err = PTR_ERR(data->hwmon_dev);
+ goto fail_remove_sysfs;
+ }
+
+
+ dev_info(&client->dev, "initialized\n");
+
+ return 0;
+
+fail_remove_sysfs:
+ sysfs_remove_group(&client->dev.kobj, &shtc1_attr_group);
+fail_free:
+ kfree(data);
+
+ return err;
+}
+
+/**
+ * shtc1_remove() - remove device
+ * @client: I2C client device
+ */
+static int shtc1_remove(struct i2c_client *client)
+{
+ struct shtc1_data *data = i2c_get_clientdata(client);
+
+ hwmon_device_unregister(data->hwmon_dev);
+ sysfs_remove_group(&client->dev.kobj, &shtc1_attr_group);
+
+ return 0;
+}
+
+/* device ID table */
+static const struct i2c_device_id shtc1_id[] = {
+ { "shtc1", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, shtc1_id);
+
+static struct i2c_driver shtc1_i2c_driver = {
+ .driver.name = "shtc1",
+ .probe = shtc1_probe,
+ .remove = shtc1_remove,
+ .id_table = shtc1_id,
+};
+
+/**
+ * shtc1_init() - initialize driver
+ *
+ * Called when kernel is booted or module is inserted.
+ * Returns 0 on success.
+ */
+static int __init shtc1_init(void)
+{
+ return i2c_add_driver(&shtc1_i2c_driver);
+}
+module_init(shtc1_init);
+
+/*
+ * shtc1_exit() - clean up driver
+ *
+ * Called when module is removed.
+ */
+static void __exit shtc1_exit(void)
+{
+ i2c_del_driver(&shtc1_i2c_driver);
+}
+
+module_exit(shtc1_exit);
+
+
+MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@...sirion.com>");
+MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/platform_data/shtc1.h b/include/linux/platform_data/shtc1.h
new file mode 100644
index 0000000..4629364
--- /dev/null
+++ b/include/linux/platform_data/shtc1.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2012 Sensirion AG, Switzerland
+ * Author: Johannes Winkelmann <johannes.winkelmann@...sirion.com>
+ *
+ * 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 __SHTC1_H_
+#define __SHTC1_H_
+
+struct shtc1_platform_data {
+ bool blocking_io;
+ bool high_precision;
+};
+
+#endif
--
1.8.3.2
--
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