Add support to read the sht15 status register. Explicitly:
* The measurement resolution through the temp_resolution and
humidity_resolution sysfs attributes;
* An end of battery indicator through the battery_alarm sysfs attribute;
* Embedded heater support using the heater_enable sysfs attribute;
* Reload from OTP available through the otp_reload sysfs attribute.
Signed-off-by: Vivien Didelot <vivien.didelot@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jerome Oufella <jerome.oufella@xxxxxxxxxxxxxxxxxxxx>
To: lm-sensors@xxxxxxxxxxxxxx
Cc: khali@xxxxxxxxxxxx
---
drivers/hwmon/sht15.c | 168 ++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 167 insertions(+), 1 deletions(-)
diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c
index 83822a6..62a1a03 100644
--- a/drivers/hwmon/sht15.c
+++ b/drivers/hwmon/sht15.c
@@ -3,6 +3,7 @@
*
* Portions Copyright (c) 2010-2011 Savoir-faire Linux Inc.
* Jerome Oufella <jerome.oufella@xxxxxxxxxxxxxxxxxxxx>
+ * Vivien Didelot <vivien.didelot@xxxxxxxxxxxxxxxxxxxx>
*
* Copyright (c) 2009 Jonathan Cameron
*
@@ -14,7 +15,6 @@
*
* Default resolution only (14bit temp, 12bit humidity)
* Checksum validation can be enabled via the checksumming sysfs attribute
- * Ignoring battery status.
* Heater not enabled.
* Timings are all conservative.
*
@@ -45,6 +45,7 @@
#define SHT15_MEASURE_TEMP 0x03
#define SHT15_MEASURE_RH 0x05
#define SHT15_SOFT_RESET 0x1E
+#define SHT15_READ_STATUS 0x07
#define SHT15_READING_NOTHING 0
#define SHT15_READING_TEMP 1
@@ -58,6 +59,12 @@
/* Min timings in msecs */
#define SHT15_TSRST 11 /* soft reset time */
+/* Status Register Bits */
+#define SHT15_STATUS_BATTERY 0x40
+#define SHT15_STATUS_HEATER 0x04
+#define SHT15_STATUS_OTP_RELOAD 0x02
+#define SHT15_STATUS_RESOLUTION 0x01
+
/**
* struct sht15_temppair - elements of voltage dependant temp calc
* @vdd: supply voltage in microvolts
@@ -114,6 +121,7 @@ static const u8 sht15_crc8_table[] = {
* @wait_queue: wait queue for getting values from device
* @val_temp: last temperature value read from device
* @val_humid: last humidity value read from device
+ * @val_status: last status register value read from device
* @checksum_ok:last value read from device passed checksum verification
* @flag: status flag used to identify what the last request was
* @valid: are the current stored values valid (start condition)
@@ -132,6 +140,11 @@ static const u8 sht15_crc8_table[] = {
* @update_supply_work: work struct that is used to update the supply_uV
* @interrupt_handled: flag used to indicate a hander has been scheduled
* @checksumming: flag used to indicate the data checksum must be validated
+ * @end_of_battery: flag used to indicate the low voltage detection
+ * @heater: flag used to indicate the heater status
+ * @no_otp_reload: flag used to indicate no reloading from OTP
+ * @temp_resolution: the temperature measurement resolution
+ * @humidity_resolution: the humidity measurement resolution
*/
struct sht15_data {
struct sht15_platform_data *pdata;
@@ -139,6 +152,7 @@ struct sht15_data {
wait_queue_head_t wait_queue;
uint16_t val_temp;
uint16_t val_humid;
+ u8 val_status;
u8 checksum_ok;
u8 flag;
u8 valid;
@@ -153,6 +167,11 @@ struct sht15_data {
struct work_struct update_supply_work;
atomic_t interrupt_handled;
u8 checksumming;
+ u8 end_of_battery;
+ u8 heater;
+ u8 no_otp_reload;
+ u8 temp_resolution;
+ u8 humidity_resolution;
};
static u8 sht15_read_byte(struct sht15_data *);
@@ -193,6 +212,26 @@ static u8 sht15_crc8(const unsigned char *data, unsigned char len)
}
/**
+ * sht15_apply_status() - update data attributes from the status
+ * @data: sht15 specific data.
+ * @status: new status to set to data.
+ */
+static void sht15_apply_status(struct sht15_data *data, u8 status)
+{
+ data->val_status = status;
+ data->end_of_battery = (status & SHT15_STATUS_BATTERY) >> 6;
+ data->heater = (status & SHT15_STATUS_HEATER) >> 2;
+ data->no_otp_reload = (status & SHT15_STATUS_OTP_RELOAD) >> 1;
+ if (status & SHT15_STATUS_RESOLUTION) {
+ data->temp_resolution = 12;
+ data->humidity_resolution = 8;
+ } else {
+ data->temp_resolution = 14;
+ data->humidity_resolution = 12;
+ }
+}
+
+/**
* sht15_connection_reset() - reset the comms interface
* @data: sht15 specific data
*
@@ -316,6 +355,49 @@ static inline void sht15_soft_reset(struct sht15_data *data)
{
sht15_send_cmd(data, SHT15_SOFT_RESET);
msleep(SHT15_TSRST);
+ /* reset attributes with default register value */
+ sht15_apply_status(data, 0);
+}
+
+/**
+ * sht15_update_status() - get the status register from device
+ * @data: device instance specific data.
+ *
+ * As described in figure 15 and table 5 of the data sheet.
+ */
+static int sht15_update_status(struct sht15_data *data)
+{
+ int ret;
+ u8 status;
+ u8 dev_checksum = 0;
+ u8 checksum_values[2];
+
+ ret = sht15_send_cmd(data, SHT15_READ_STATUS);
+ if (ret)
+ return ret;
+ status = sht15_read_byte(data);
+
+ if (data->checksumming) {
+ sht15_ack(data);
+ dev_checksum = reverse(sht15_read_byte(data));
+ checksum_values[0] = SHT15_READ_STATUS;
+ checksum_values[1] = status;
+ data->checksum_ok = (sht15_crc8(checksum_values, 2) == dev_checksum);
+ }
+
+ sht15_end_transmission(data);
+
+ /*
+ * Perform checksum validation on the received data.
+ * Specification mentions that in case a checksum verification fails,
+ * a soft reset command must be sent to the device.
+ */
+ if (data->checksumming && !data->checksum_ok) {
+ sht15_soft_reset(data);
+ return -EAGAIN;
+ }
+ sht15_apply_status(data, status);
+ return 0;
}
/**
@@ -378,6 +460,9 @@ static int sht15_update_vals(struct sht15_data *data)
mutex_lock(&data->read_lock);
if (time_after(jiffies, data->last_updat + timeout)
|| !data->valid) {
+ ret = sht15_update_status(data);
+ if (ret)
+ goto error_ret;
data->flag = SHT15_READING_HUMID;
ret = sht15_update_single_val(data, SHT15_MEASURE_RH, 160);
if (ret)
@@ -442,6 +527,71 @@ static inline int sht15_calc_humid(struct sht15_data *data)
/ 1000000 + RHlinear;
}
+static ssize_t sht15_show_battery(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret;
+ struct sht15_data *data = dev_get_drvdata(dev);
+
+ /* Technically no need to read temperature and humidity as well */
+ ret = sht15_update_vals(data);
+
+ return ret ? ret : sprintf(buf, "%d\n", data->end_of_battery);
+}
+
+static ssize_t sht15_show_heater(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret;
+ struct sht15_data *data = dev_get_drvdata(dev);
+
+ /* Technically no need to read temperature and humidity as well */
+ ret = sht15_update_vals(data);
+
+ return ret ? ret : sprintf(buf, "%d\n", data->heater);
+}
+
+static ssize_t sht15_show_otp_reload(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret;
+ struct sht15_data *data = dev_get_drvdata(dev);
+
+ /* Technically no need to read temperature and humidity as well */
+ ret = sht15_update_vals(data);
+
+ return ret ? ret : sprintf(buf, "%d\n", !(data->no_otp_reload));
+}
+
+static ssize_t sht15_show_temp_resolution(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret;
+ struct sht15_data *data = dev_get_drvdata(dev);
+
+ /* Technically no need to read temperature and humidity as well */
+ ret = sht15_update_vals(data);
+
+ return ret ? ret : sprintf(buf, "%d\n", data->temp_resolution);
+}
+
+static ssize_t sht15_show_humidity_resolution(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret;
+ struct sht15_data *data = dev_get_drvdata(dev);
+
+ /* Technically no need to read temperature and humidity as well */
+ ret = sht15_update_vals(data);
+
+ return ret ? ret : sprintf(buf, "%d\n", data->humidity_resolution);
+}
+
static ssize_t sht15_show_temp(struct device *dev,
struct device_attribute *attr,
char *buf)
@@ -510,6 +660,17 @@ static SENSOR_DEVICE_ATTR(temp1_input,
static SENSOR_DEVICE_ATTR(humidity1_input,
S_IRUGO, sht15_show_humidity,
NULL, 0);
+static DEVICE_ATTR(battery_alarm, S_IRUGO, sht15_show_battery, NULL);
+static DEVICE_ATTR(heater_enable, S_IRUGO, sht15_show_heater, NULL);
+static DEVICE_ATTR(otp_reload, S_IRUGO, sht15_show_otp_reload, NULL);
+static DEVICE_ATTR(temp_resolution,
+ S_IRUGO,
+ sht15_show_temp_resolution,
+ NULL);
+static DEVICE_ATTR(humidity_resolution,
+ S_IRUGO,
+ sht15_show_humidity_resolution,
+ NULL);
static DEVICE_ATTR(checksumming,
S_IRUGO | S_IWUSR,
sht15_show_checksum,
@@ -518,6 +679,11 @@ static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
static struct attribute *sht15_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_humidity1_input.dev_attr.attr,
+ &dev_attr_battery_alarm.attr,
+ &dev_attr_heater_enable.attr,
+ &dev_attr_otp_reload.attr,
+ &dev_attr_temp_resolution.attr,
+ &dev_attr_humidity_resolution.attr,
&dev_attr_checksumming.attr,
&dev_attr_name.attr,
NULL,
--
1.7.1
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