Hi Jonathan, > Is there actualy a use case that means these can't both be set > by platform data? Also, if these are acceptable, should they have > some means of indicating which combination of values are available? I can imagine a use case where an embedded device wants to operate in a low-power mode while still monitoring humidity and/or temperature. Measurement time and thus power consumption of the SHT21 are significantly smaller when using a low resolution. Or you can use a low resolution while waiting for a significant change in humidity and/or temperature and then switch to a higher resolution to actually report the measurement values. > Rely on platform data to get this right rather than an adhoc test that > might well pass on some random devices. I removed that probing stuff. As read and write addresses for the user register are different, it would probably not pass on another device, but it could disturb another device. > Sorry to say I missed some error handling issues the first time around. > Please always provide userspace with the most detailed and correct error > possible. Normally this is the one comming up from the bus subsystem. All error codes should now be passed up to userspace. Thanks again, Urs Signed-off-by: Urs Fleisch <urs.fleisch@xxxxxxxxxxxxx> --- diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig index 95ccbe3..4a96429 100644 --- a/drivers/hwmon/Kconfig +++ b/drivers/hwmon/Kconfig @@ -688,6 +688,16 @@ config SENSORS_SHT15 This driver can also be built as a module. If so, the module will be called sht15. +config SENSORS_SHT21 + tristate "Sensiron humidity and temperature sensors. SHT21 and compat." + depends on I2C + help + If you say yes here you get support for the Sensiron SHT21, SHT25 + humidity and temperature sensors. + + This driver can also be built as a module. If so, the module + will be called sht21. + config SENSORS_S3C tristate "S3C24XX/S3C64XX Inbuilt ADC" depends on ARCH_S3C2410 diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile index 33c2ee1..7439653 100644 --- a/drivers/hwmon/Makefile +++ b/drivers/hwmon/Makefile @@ -80,6 +80,7 @@ obj-$(CONFIG_SENSORS_PC87427) += pc87427.o obj-$(CONFIG_SENSORS_PCF8591) += pcf8591.o obj-$(CONFIG_SENSORS_S3C) += s3c-hwmon.o obj-$(CONFIG_SENSORS_SHT15) += sht15.o +obj-$(CONFIG_SENSORS_SHT21) += sht21.o obj-$(CONFIG_SENSORS_SIS5595) += sis5595.o obj-$(CONFIG_SENSORS_SMM665) += smm665.o obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o diff --git a/drivers/hwmon/sht21.c b/drivers/hwmon/sht21.c new file mode 100644 index 0000000..7d3ec82 --- /dev/null +++ b/drivers/hwmon/sht21.c @@ -0,0 +1,592 @@ +/* Sensirion SHT21 humidity and temperature sensor driver + * + * Copyright (C) 2010 Urs Fleisch <urs.fleisch@xxxxxxxxxxxxx> + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA + * + * Data sheet available (5/2010) at + * http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT21.pdf + */ + +#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/mutex.h> +#include <linux/device.h> + +/* I2C commands bytes */ +#define SHT21_TRIG_T_MEASUREMENT_HM 0xe3 +#define SHT21_TRIG_RH_MEASUREMENT_HM 0xe5 +#define SHT21_USER_REG_W 0xe6 +#define SHT21_USER_REG_R 0xe7 + +/* User register bit masks */ +#define SHT21_RES_12_14BIT 0x00 +#define SHT21_RES_8_12BIT 0x01 +#define SHT21_RES_10_13BIT 0x80 +#define SHT21_RES_11_11BIT 0x81 +#define SHT21_RES_MASK 0x81 +#define SHT21_END_OF_BATTERY 0x40 +#define SHT21_ENABLE_HEATER 0x04 + +/** + * struct sht21 - SHT21 device specific data + * @hwmon_dev: device registered with hwmon + * @lock: mutex to protect measurement values and read-modify-write access to + * user register + * @valid: only 0 before first measurement is taken + * @last_update: time of last update (jiffies) + * @temperature: cached temperature measurement value + * @humidity: cached humidity measurement value + */ +struct sht21 { + struct device *hwmon_dev; + struct mutex lock; + char valid; + unsigned long last_update; + int temperature; + int humidity; +}; + +/** + * sht21_temp_ticks_to_millicelsius() - convert raw temperature ticks to + * milli celsius + * @ticks: temperature ticks value received from sensor + */ +static inline int sht21_temp_ticks_to_millicelsius(int ticks) +{ + ticks &= ~0x0003; /* clear status bits */ + /* Formula T = -46.85 + 175.72 * ST / 2^16 from data sheet 6.2, + optimized for integer fixed point (3 digits) arithmetic */ + return ((21965 * ticks) >> 13) - 46850; +} + +/** + * sht21_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to + * one-thousandths of a percent relative humidity + * @ticks: humidity ticks value received from sensor + */ +static inline int sht21_rh_ticks_to_per_cent_mille(int ticks) +{ + ticks &= ~0x0003; /* clear status bits */ + /* Formula RH = -6 + 125 * SRH / 2^16 from data sheet 6.1, + optimized for integer fixed point (3 digits) arithmetic */ + return ((15625 * ticks) >> 13) - 6000; +} + +/** + * sht21_update_measurements() - get updated measurements from device + * @client: I2C client device + * + * Returns 0 on success, else negative errno. + */ +static int sht21_update_measurements(struct i2c_client *client) +{ + int result = 0; + struct sht21 *sht21 = i2c_get_clientdata(client); + + mutex_lock(&sht21->lock); + /* Data sheet 2.4: + * SHT2x should not be active for more than 10% of the time - e.g. + * maximum two measurements per second at 12bit accuracy shall be made. + */ + if (time_after(jiffies, sht21->last_update + HZ / 2) || !sht21->valid) { + result = i2c_smbus_read_word_data(client, + SHT21_TRIG_T_MEASUREMENT_HM); + /* SMBus specifies low byte first, but the SHT21 returns MSB + * first, so we have to swab16 the values */ + if (result >= 0) { + sht21->temperature = sht21_temp_ticks_to_millicelsius( + swab16(result)); + result = i2c_smbus_read_word_data(client, + SHT21_TRIG_RH_MEASUREMENT_HM); + if (result >= 0) { + sht21->humidity = + sht21_rh_ticks_to_per_cent_mille( + swab16(result)); + sht21->last_update = jiffies; + sht21->valid = 1; + } + } + } + mutex_unlock(&sht21->lock); + + return result >= 0 ? 0 : result; +} + +/** + * sht21_show_temperature() - show temperature measurement value in sysfs + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to + * + * Will be called on read access to temp1_input sysfs attribute. + * Returns number of bytes written into buffer, negative errno on error. + */ +static ssize_t sht21_show_temperature(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + int result = sht21_update_measurements(client); + if (result >= 0) { + struct sht21 *sht21 = i2c_get_clientdata(client); + + return sprintf(buf, "%d\n", sht21->temperature); + } + return result; +} + +/** + * sht21_show_humidity() - show humidity measurement value in sysfs + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to + * + * Will be called on read access to humidity1_input sysfs attribute. + * Returns number of bytes written into buffer, negative errno on error. + */ +static ssize_t sht21_show_humidity(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + int result = sht21_update_measurements(client); + if (result >= 0) { + struct sht21 *sht21 = i2c_get_clientdata(client); + + return sprintf(buf, "%d\n", sht21->humidity); + } + return result; +} + +/** + * sht21_read_user_register() - read user register + * @dev: device + * + * Returns byte value of user register, negative errno on error. + */ +static s32 sht21_read_user_register(struct device *dev) +{ + struct i2c_client *client = to_i2c_client(dev); + struct sht21 *sht21 = i2c_get_clientdata(client); + s32 result; + mutex_lock(&sht21->lock); + result = i2c_smbus_read_byte_data(client, SHT21_USER_REG_R); + mutex_unlock(&sht21->lock); + return result; +} + +/** + * sht21_modify_user_register() - modify user register + * @dev: device + * @mask: mask of bits to modify + * @value: bits to write into user register + * + * Returns 0 on success, negative errno on error. + */ +static s32 sht21_modify_user_register(struct device *dev, u8 mask, u8 value) +{ + struct i2c_client *client = to_i2c_client(dev); + struct sht21 *sht21 = i2c_get_clientdata(client); + s32 result; + + mutex_lock(&sht21->lock); + result = i2c_smbus_read_byte_data(client, SHT21_USER_REG_R); + if (result >= 0) + result = i2c_smbus_write_byte_data(client, SHT21_USER_REG_W, + (result & ~mask) | (value & mask)); + mutex_unlock(&sht21->lock); + + return result; +} + +/** + * sht21_show_temperature_resolution() - show temperature measurement resolution + * bits in sysfs + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer (PAGE_SIZE) where user register value is written to + * + * Will be called on read access to temp1_resolution_bits sysfs attribute. + * Writes "11", "12", "13" or "14". + * Returns number of bytes written into buffer, negative errno on error. + */ +static ssize_t sht21_show_temperature_resolution(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + s32 userreg = sht21_read_user_register(dev); + if (userreg >= 0) { + int resolution; + switch (userreg & SHT21_RES_MASK) { + case SHT21_RES_8_12BIT: + resolution = 12; + break; + case SHT21_RES_10_13BIT: + resolution = 13; + break; + case SHT21_RES_11_11BIT: + resolution = 11; + break; + case SHT21_RES_12_14BIT: + default: + resolution = 14; + } + return sprintf(buf, "%d\n", resolution); + } + return userreg; +} + +/** + * sht21_store_temperature_resolution() - set temperature measurement resolution + * bits from sysfs value + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer containing value "11", "12", "13" or "14" + * @count: number of characters in @buf + * + * Will be called on write access to temp1_resolution_bits sysfs attribute. + * Returns @count, negative errno on error. + */ +static ssize_t sht21_store_temperature_resolution(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + s32 result; + u8 res_bits; + unsigned long value; + if (strict_strtoul(buf, 10, &value)) + return -EINVAL; + + switch (value) { + case 11: + res_bits = SHT21_RES_11_11BIT; + break; + case 12: + res_bits = SHT21_RES_8_12BIT; + break; + case 13: + res_bits = SHT21_RES_10_13BIT; + break; + case 14: + res_bits = SHT21_RES_12_14BIT; + break; + default: + return -EINVAL; + } + + result = sht21_modify_user_register(dev, SHT21_RES_MASK, res_bits); + + return result >= 0 ? count : result; +} + +/** + * sht21_show_humidity_resolution() - show humidity measurement resolution + * bits in sysfs + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer (PAGE_SIZE) where user register value is written to + * + * Will be called on read access to humidity1_resolution_bits sysfs attribute. + * Writes "8", "10", "11" or "12". + * Returns number of bytes written into buffer, negative errno on error. + */ +static ssize_t sht21_show_humidity_resolution(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + s32 userreg = sht21_read_user_register(dev); + if (userreg >= 0) { + int resolution; + switch (userreg & SHT21_RES_MASK) { + case SHT21_RES_8_12BIT: + resolution = 8; + break; + case SHT21_RES_10_13BIT: + resolution = 10; + break; + case SHT21_RES_11_11BIT: + resolution = 11; + break; + case SHT21_RES_12_14BIT: + default: + resolution = 12; + } + return sprintf(buf, "%d\n", resolution); + } + return userreg; +} + +/** + * sht21_store_humidity_resolution() - set humidity measurement resolution + * bits from sysfs value + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer containing value "8", "10", "11" or "12" + * @count: number of characters in @buf + * + * Will be called on write access to humidity1_resolution_bits sysfs attribute. + * Returns @count, negative errno on error. + */ +static ssize_t sht21_store_humidity_resolution(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + s32 result; + u8 res_bits; + unsigned long value; + if (strict_strtoul(buf, 10, &value)) + return -EINVAL; + + switch (value) { + case 8: + res_bits = SHT21_RES_8_12BIT; + break; + case 10: + res_bits = SHT21_RES_10_13BIT; + break; + case 11: + res_bits = SHT21_RES_11_11BIT; + break; + case 12: + res_bits = SHT21_RES_12_14BIT; + break; + default: + return -EINVAL; + } + + result = sht21_modify_user_register(dev, SHT21_RES_MASK, res_bits); + + return result >= 0 ? count : result; +} + +/** + * sht21_show_end_of_battery() - show end of battery state in sysfs + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer (PAGE_SIZE) where user register value is written to + * + * Will be called on read access to in0_min_alarm sysfs attribute. + * Writes "1" if VDD < 2.25V, else "0". + * Returns number of bytes written into buffer, negative errno on error. + */ +static ssize_t sht21_show_end_of_battery(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + s32 userreg = sht21_read_user_register(dev); + if (userreg >= 0) + return sprintf(buf, "%u\n", !!(userreg & SHT21_END_OF_BATTERY)); + else + return userreg; +} + +/** + * sht21_show_heater_enable() - show on-chip heater state in sysfs + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer (PAGE_SIZE) where user register value is written to + * + * Will be called on read access to heater_enable sysfs attribute. + * Writes "1" if heater is enabled, else "0". + * Returns number of bytes written into buffer, negative errno on error. + */ +static ssize_t sht21_show_heater_enable(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + s32 userreg = sht21_read_user_register(dev); + if (userreg >= 0) + return sprintf(buf, "%u\n", !!(userreg & SHT21_ENABLE_HEATER)); + else + return userreg; +} + +/** + * sht21_store_heater_enable() - enable or disable heater from sysfs value + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer containing value "0" or "1" + * @count: number of characters in @buf + * + * Will be called on write access to heater_enable sysfs attribute. + * Returns @count, negative errno on error. + */ +static ssize_t sht21_store_heater_enable(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + s32 result; + unsigned long value; + if (strict_strtoul(buf, 10, &value) || value > 1) + return -EINVAL; + + result = sht21_modify_user_register(dev, SHT21_ENABLE_HEATER, + value ? SHT21_ENABLE_HEATER : 0); + + return result >= 0 ? count : result; +} + + +/* sysfs attributes */ +static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, sht21_show_temperature, + NULL, 0); +static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, sht21_show_humidity, + NULL, 0); +static SENSOR_DEVICE_ATTR(temp1_resolution_bits, S_IRUGO | S_IWUSR, + sht21_show_temperature_resolution, sht21_store_temperature_resolution, + 0); +static SENSOR_DEVICE_ATTR(humidity1_resolution_bits, S_IRUGO | S_IWUSR, + sht21_show_humidity_resolution, sht21_store_humidity_resolution, 0); +static SENSOR_DEVICE_ATTR(in0_min_alarm, S_IRUGO, sht21_show_end_of_battery, + NULL, 0); +static SENSOR_DEVICE_ATTR(heater_enable, S_IRUGO | S_IWUSR, + sht21_show_heater_enable, sht21_store_heater_enable, 0); + +static struct attribute *sht21_attributes[] = { + &sensor_dev_attr_temp1_input.dev_attr.attr, + &sensor_dev_attr_humidity1_input.dev_attr.attr, + &sensor_dev_attr_temp1_resolution_bits.dev_attr.attr, + &sensor_dev_attr_humidity1_resolution_bits.dev_attr.attr, + &sensor_dev_attr_in0_min_alarm.dev_attr.attr, + &sensor_dev_attr_heater_enable.dev_attr.attr, + NULL +}; + +static const struct attribute_group sht21_attr_group = { + .attrs = sht21_attributes, +}; + +/** + * sht21_probe() - probe device + * @client: I2C client device + * @id: device ID + * + * Called by the I2C core when an entry in the ID table matches a + * device's name. + * Returns 0 on success. + */ +static int __devinit sht21_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct sht21 *sht21; + int status; + + if (!i2c_check_functionality(client->adapter, + I2C_FUNC_SMBUS_WORD_DATA)) { + dev_err(&client->dev, + "adapter does not support SMBus word transactions\n"); + return -ENODEV; + } + + sht21 = kzalloc(sizeof(*sht21), GFP_KERNEL); + if (!sht21) { + dev_dbg(&client->dev, "kzalloc failed\n"); + return -ENOMEM; + } + i2c_set_clientdata(client, sht21); + + status = i2c_smbus_read_byte_data(client, SHT21_USER_REG_R); + if (status < 0) { + dev_err(&client->dev, "error reading user register\n"); + goto fail_free; + } + + mutex_init(&sht21->lock); + + status = sysfs_create_group(&client->dev.kobj, &sht21_attr_group); + if (status) { + dev_dbg(&client->dev, "could not create sysfs files\n"); + goto fail_free; + } + sht21->hwmon_dev = hwmon_device_register(&client->dev); + if (IS_ERR(sht21->hwmon_dev)) { + dev_dbg(&client->dev, "unable to register hwmon device\n"); + status = PTR_ERR(sht21->hwmon_dev); + goto fail_remove_sysfs; + } + + dev_info(&client->dev, "initialized\n"); + + return 0; + +fail_remove_sysfs: + sysfs_remove_group(&client->dev.kobj, &sht21_attr_group); +fail_free: + kfree(sht21); + + return status; +} + +/** + * sht21_remove() - remove device + * @client: I2C client device + */ +static int __devexit sht21_remove(struct i2c_client *client) +{ + struct sht21 *sht21 = i2c_get_clientdata(client); + + hwmon_device_unregister(sht21->hwmon_dev); + sysfs_remove_group(&client->dev.kobj, &sht21_attr_group); + kfree(sht21); + + return 0; +} + +/* Device ID table */ +static const struct i2c_device_id sht21_id[] = { + { "sht21", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, sht21_id); + +static struct i2c_driver sht21_driver = { + .driver.name = "sht21", + .probe = sht21_probe, + .remove = __devexit_p(sht21_remove), + .id_table = sht21_id, +}; + +/** + * sht21_init() - initialize driver + * + * Called when kernel is booted or module is inserted. + * Returns 0 on success. + */ +static int __init sht21_init(void) +{ + return i2c_add_driver(&sht21_driver); +} +module_init(sht21_init); + +/** + * sht21_init() - clean up driver + * + * Called when module is removed. + */ +static void __exit sht21_exit(void) +{ + i2c_del_driver(&sht21_driver); +} +module_exit(sht21_exit); + +MODULE_AUTHOR("Urs Fleisch <urs.fleisch@xxxxxxxxxxxxx>"); +MODULE_DESCRIPTION("Sensirion SHT21 humidity and temperature sensor driver"); +MODULE_LICENSE("GPL"); _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
