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hwmon: (sht15) add support for the status register
* Add support for: - Heater. - End of battery notice. - Ability not to reload from OTP. - Low resolution (12bit temp, 8bit humidity). * Add an utility function to read individual bytes from the device. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Acked-by: Jonathan Cameron <jic23@cam.ac.uk> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
This commit is contained in:
Vivien Didelot
Guenter Roeck
parent
181148ae68
commit
cc15c7ebb4
@ -4,6 +4,7 @@ Kernel driver sht15
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Authors:
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* Wouter Horre
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* Jonathan Cameron
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* Vivien Didelot <vivien.didelot@savoirfairelinux.com>
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Supported chips:
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* Sensirion SHT10
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@ -30,13 +31,37 @@ Description
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The SHT10, SHT11, SHT15, SHT71, and SHT75 are humidity and temperature
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sensors.
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The devices communicate using two GPIO lines and use the default
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resolution settings of 14 bits for temperature and 12 bits for humidity.
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The devices communicate using two GPIO lines.
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Supported resolutions for the measurements are 14 bits for temperature and 12
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bits for humidity, or 12 bits for temperature and 8 bits for humidity.
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The humidity calibration coefficients are programmed into an OTP memory on the
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chip. These coefficients are used to internally calibrate the signals from the
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sensors. Disabling the reload of those coefficients allows saving 10ms for each
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measurement and decrease power consumption, while loosing on precision.
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Some options may be set directly in the sht15_platform_data structure
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or via sysfs attributes.
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Note: The regulator supply name is set to "vcc".
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Platform data
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-------------
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* no_otp_reload:
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flag to indicate not to reload from OTP (default to false).
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* low_resolution:
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flag to indicate the temp/humidity resolution to use (default to false).
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Sysfs interface
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---------------
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* temp1_input: temperature input
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* humidity1_input: humidity input
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* heater_enable: write 1 in this attribute to enable the on-chip heater,
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0 to disable it. Be careful not to enable the heater
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for too long.
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* temp1_fault: if 1, this means that the voltage is low (below 2.47V) and
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measurement may be invalid.
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* humidity1_fault: same as temp1_fault.
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@ -1,6 +1,9 @@
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/*
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* sht15.c - support for the SHT15 Temperature and Humidity Sensor
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*
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* Portions Copyright (c) 2010-2011 Savoir-faire Linux Inc.
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* Vivien Didelot <vivien.didelot@savoirfairelinux.com>
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*
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* Copyright (c) 2009 Jonathan Cameron
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*
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* Copyright (c) 2007 Wouter Horre
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@ -33,6 +36,8 @@
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/* Commands */
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#define SHT15_MEASURE_TEMP 0x03
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#define SHT15_MEASURE_RH 0x05
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#define SHT15_WRITE_STATUS 0x06
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#define SHT15_READ_STATUS 0x07
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#define SHT15_SOFT_RESET 0x1E
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/* Min timings */
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@ -41,6 +46,12 @@
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#define SHT15_TSU 150 /* (nsecs) data setup time */
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#define SHT15_TSRST 11 /* (msecs) soft reset time */
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/* Status Register Bits */
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#define SHT15_STATUS_LOW_RESOLUTION 0x01
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#define SHT15_STATUS_NO_OTP_RELOAD 0x02
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#define SHT15_STATUS_HEATER 0x04
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#define SHT15_STATUS_LOW_BATTERY 0x40
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/* Actions the driver may be doing */
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enum sht15_state {
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SHT15_READING_NOTHING,
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@ -74,9 +85,12 @@ static const struct sht15_temppair temppoints[] = {
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* @wait_queue: wait queue for getting values from device.
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* @val_temp: last temperature value read from device.
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* @val_humid: last humidity value read from device.
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* @val_status: last status register value read from device.
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* @state: state identifying the action the driver is doing.
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* @measurements_valid: are the current stored measures valid (start condition).
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* @status_valid: is the current stored status valid (start condition).
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* @last_measurement: time of last measure.
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* @last_status: time of last status reading.
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* @read_lock: mutex to ensure only one read in progress at a time.
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* @dev: associate device structure.
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* @hwmon_dev: device associated with hwmon subsystem.
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@ -97,9 +111,12 @@ struct sht15_data {
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wait_queue_head_t wait_queue;
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uint16_t val_temp;
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uint16_t val_humid;
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u8 val_status;
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enum sht15_state state;
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bool measurements_valid;
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bool status_valid;
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unsigned long last_measurement;
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unsigned long last_status;
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struct mutex read_lock;
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struct device *dev;
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struct device *hwmon_dev;
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@ -244,10 +261,105 @@ static int sht15_soft_reset(struct sht15_data *data)
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if (ret)
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return ret;
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msleep(SHT15_TSRST);
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/* device resets default hardware status register value */
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data->val_status = 0;
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return ret;
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}
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/**
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* sht15_end_transmission() - notify device of end of transmission
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* @data: device state.
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*
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* This is basically a NAK (single clock pulse, data high).
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*/
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static void sht15_end_transmission(struct sht15_data *data)
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{
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gpio_direction_output(data->pdata->gpio_data, 1);
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ndelay(SHT15_TSU);
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gpio_set_value(data->pdata->gpio_sck, 1);
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ndelay(SHT15_TSCKH);
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gpio_set_value(data->pdata->gpio_sck, 0);
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ndelay(SHT15_TSCKL);
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}
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/**
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* sht15_read_byte() - Read a byte back from the device
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* @data: device state.
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*/
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static u8 sht15_read_byte(struct sht15_data *data)
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{
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int i;
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u8 byte = 0;
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for (i = 0; i < 8; ++i) {
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byte <<= 1;
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gpio_set_value(data->pdata->gpio_sck, 1);
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ndelay(SHT15_TSCKH);
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byte |= !!gpio_get_value(data->pdata->gpio_data);
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gpio_set_value(data->pdata->gpio_sck, 0);
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ndelay(SHT15_TSCKL);
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}
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return byte;
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}
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/**
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* sht15_send_status() - write the status register byte
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* @data: sht15 specific data.
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* @status: the byte to set the status register with.
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*
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* As described in figure 14 and table 5 of the datasheet.
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*/
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static int sht15_send_status(struct sht15_data *data, u8 status)
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{
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int ret;
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ret = sht15_send_cmd(data, SHT15_WRITE_STATUS);
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if (ret)
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return ret;
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gpio_direction_output(data->pdata->gpio_data, 1);
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ndelay(SHT15_TSU);
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sht15_send_byte(data, status);
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ret = sht15_wait_for_response(data);
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if (ret)
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return ret;
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data->val_status = status;
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return 0;
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}
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/**
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* sht15_update_status() - get updated status register from device if too old
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* @data: device instance specific data.
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*
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* As described in figure 15 and table 5 of the datasheet.
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*/
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static int sht15_update_status(struct sht15_data *data)
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{
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int ret = 0;
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u8 status;
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int timeout = HZ;
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mutex_lock(&data->read_lock);
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if (time_after(jiffies, data->last_status + timeout)
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|| !data->status_valid) {
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ret = sht15_send_cmd(data, SHT15_READ_STATUS);
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if (ret)
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goto error_ret;
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status = sht15_read_byte(data);
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sht15_end_transmission(data);
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data->val_status = status;
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data->status_valid = true;
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data->last_status = jiffies;
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}
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error_ret:
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mutex_unlock(&data->read_lock);
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return ret;
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}
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/**
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* sht15_measurement() - get a new value from device
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* @data: device instance specific data
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@ -324,6 +436,7 @@ error_ret:
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static inline int sht15_calc_temp(struct sht15_data *data)
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{
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int d1 = temppoints[0].d1;
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int d2 = (data->val_status & SHT15_STATUS_LOW_RESOLUTION) ? 40 : 10;
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int i;
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for (i = ARRAY_SIZE(temppoints) - 1; i > 0; i--)
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@ -336,7 +449,7 @@ static inline int sht15_calc_temp(struct sht15_data *data)
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break;
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}
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return data->val_temp * 10 + d1;
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return data->val_temp * d2 + d1;
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}
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/**
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@ -353,18 +466,85 @@ static inline int sht15_calc_humid(struct sht15_data *data)
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{
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int rh_linear; /* milli percent */
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int temp = sht15_calc_temp(data);
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int c2, c3;
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int t2;
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const int c1 = -4;
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const int c2 = 40500; /* x 10 ^ -6 */
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const int c3 = -28; /* x 10 ^ -7 */
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if (data->val_status & SHT15_STATUS_LOW_RESOLUTION) {
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c2 = 648000; /* x 10 ^ -6 */
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c3 = -7200; /* x 10 ^ -7 */
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t2 = 1280;
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} else {
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c2 = 40500; /* x 10 ^ -6 */
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c3 = -28; /* x 10 ^ -7 */
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t2 = 80;
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}
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rh_linear = c1 * 1000
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+ c2 * data->val_humid / 1000
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+ (data->val_humid * data->val_humid * c3) / 10000;
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return (temp - 25000) * (10000 + 80 * data->val_humid)
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return (temp - 25000) * (10000 + t2 * data->val_humid)
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/ 1000000 + rh_linear;
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}
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/**
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* sht15_show_status() - show status information in sysfs
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* @dev: device.
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* @attr: device attribute.
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* @buf: sysfs buffer where information is written to.
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*
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* Will be called on read access to temp1_fault, humidity1_fault
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* and heater_enable sysfs attributes.
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* Returns number of bytes written into buffer, negative errno on error.
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*/
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static ssize_t sht15_show_status(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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int ret;
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struct sht15_data *data = dev_get_drvdata(dev);
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u8 bit = to_sensor_dev_attr(attr)->index;
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ret = sht15_update_status(data);
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return ret ? ret : sprintf(buf, "%d\n", !!(data->val_status & bit));
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}
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/**
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* sht15_store_heater() - change heater state via sysfs
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* @dev: device.
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* @attr: device attribute.
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* @buf: sysfs buffer to read the new heater state from.
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* @count: length of the data.
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*
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* Will be called on read access to heater_enable sysfs attribute.
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* Returns number of bytes actually decoded, negative errno on error.
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*/
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static ssize_t sht15_store_heater(struct device *dev,
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struct device_attribute *attr,
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const char *buf, size_t count)
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{
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int ret;
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struct sht15_data *data = dev_get_drvdata(dev);
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long value;
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u8 status;
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if (strict_strtol(buf, 10, &value))
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return -EINVAL;
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mutex_lock(&data->read_lock);
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status = data->val_status & 0x07;
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if (!!value)
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status |= SHT15_STATUS_HEATER;
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else
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status &= ~SHT15_STATUS_HEATER;
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ret = sht15_send_status(data, status);
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mutex_unlock(&data->read_lock);
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return ret ? ret : count;
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}
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/**
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* sht15_show_temp() - show temperature measurement value in sysfs
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* @dev: device.
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@ -407,7 +587,6 @@ static ssize_t sht15_show_humidity(struct device *dev,
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ret = sht15_update_measurements(data);
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return ret ? ret : sprintf(buf, "%d\n", sht15_calc_humid(data));
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}
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static ssize_t show_name(struct device *dev,
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@ -422,10 +601,19 @@ static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
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sht15_show_temp, NULL, 0);
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static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO,
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sht15_show_humidity, NULL, 0);
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static SENSOR_DEVICE_ATTR(temp1_fault, S_IRUGO, sht15_show_status, NULL,
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SHT15_STATUS_LOW_BATTERY);
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static SENSOR_DEVICE_ATTR(humidity1_fault, S_IRUGO, sht15_show_status, NULL,
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SHT15_STATUS_LOW_BATTERY);
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static SENSOR_DEVICE_ATTR(heater_enable, S_IRUGO | S_IWUSR, sht15_show_status,
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sht15_store_heater, SHT15_STATUS_HEATER);
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static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
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static struct attribute *sht15_attrs[] = {
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&sensor_dev_attr_temp1_input.dev_attr.attr,
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&sensor_dev_attr_humidity1_input.dev_attr.attr,
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&sensor_dev_attr_temp1_fault.dev_attr.attr,
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&sensor_dev_attr_humidity1_fault.dev_attr.attr,
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&sensor_dev_attr_heater_enable.dev_attr.attr,
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&dev_attr_name.attr,
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NULL,
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};
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@ -466,25 +654,8 @@ static void sht15_ack(struct sht15_data *data)
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gpio_direction_input(data->pdata->gpio_data);
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}
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/**
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* sht15_end_transmission() - notify device of end of transmission
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* @data: device state
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*
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* This is basically a NAK. (single clock pulse, data high)
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*/
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static void sht15_end_transmission(struct sht15_data *data)
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{
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gpio_direction_output(data->pdata->gpio_data, 1);
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ndelay(SHT15_TSU);
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gpio_set_value(data->pdata->gpio_sck, 1);
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ndelay(SHT15_TSCKH);
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gpio_set_value(data->pdata->gpio_sck, 0);
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ndelay(SHT15_TSCKL);
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}
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static void sht15_bh_read_data(struct work_struct *work_s)
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{
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int i;
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uint16_t val = 0;
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struct sht15_data *data
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= container_of(work_s, struct sht15_data,
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@ -505,16 +676,10 @@ static void sht15_bh_read_data(struct work_struct *work_s)
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}
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/* Read the data back from the device */
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for (i = 0; i < 16; ++i) {
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val <<= 1;
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gpio_set_value(data->pdata->gpio_sck, 1);
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ndelay(SHT15_TSCKH);
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val |= !!gpio_get_value(data->pdata->gpio_data);
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gpio_set_value(data->pdata->gpio_sck, 0);
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ndelay(SHT15_TSCKL);
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if (i == 7)
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sht15_ack(data);
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}
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val = sht15_read_byte(data);
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val <<= 8;
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sht15_ack(data);
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val |= sht15_read_byte(data);
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/* Tell the device we are done */
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sht15_end_transmission(data);
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@ -568,6 +733,7 @@ static int __devinit sht15_probe(struct platform_device *pdev)
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{
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int ret = 0;
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struct sht15_data *data = kzalloc(sizeof(*data), GFP_KERNEL);
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u8 status = 0;
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if (!data) {
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ret = -ENOMEM;
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@ -588,6 +754,10 @@ static int __devinit sht15_probe(struct platform_device *pdev)
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}
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data->pdata = pdev->dev.platform_data;
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data->supply_uV = data->pdata->supply_mv * 1000;
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if (data->pdata->no_otp_reload)
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status |= SHT15_STATUS_NO_OTP_RELOAD;
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if (data->pdata->low_resolution)
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status |= SHT15_STATUS_LOW_RESOLUTION;
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/*
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* If a regulator is available,
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@ -646,6 +816,13 @@ static int __devinit sht15_probe(struct platform_device *pdev)
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if (ret)
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goto err_release_irq;
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/* write status with platform data options */
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if (status) {
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ret = sht15_send_status(data, status);
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if (ret)
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goto err_release_irq;
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}
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ret = sysfs_create_group(&pdev->dev.kobj, &sht15_attr_group);
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if (ret) {
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dev_err(&pdev->dev, "sysfs create failed\n");
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@ -689,6 +866,10 @@ static int __devexit sht15_remove(struct platform_device *pdev)
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* prevent new ones beginning
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*/
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mutex_lock(&data->read_lock);
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if (sht15_soft_reset(data)) {
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mutex_unlock(&data->read_lock);
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return -EFAULT;
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}
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hwmon_device_unregister(data->hwmon_dev);
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sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group);
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if (!IS_ERR(data->reg)) {
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@ -19,10 +19,14 @@
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* @gpio_sck: no. of gpio to which the data clock is connected.
|
||||
* @supply_mv: supply voltage in mv. Overridden by regulator if
|
||||
* available.
|
||||
* @no_otp_reload: flag to indicate no reload from OTP.
|
||||
* @low_resolution: flag to indicate the temp/humidity resolution to use.
|
||||
*/
|
||||
struct sht15_platform_data {
|
||||
int gpio_data;
|
||||
int gpio_sck;
|
||||
int supply_mv;
|
||||
bool no_otp_reload;
|
||||
bool low_resolution;
|
||||
};
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user