Expose the per-chip unique identifier so it can be used to identify the
sensor producing the measurements.
Signed-off-by: Peter A. Bigot <pab@xxxxxxxxxxx>
---
Documentation/hwmon/sht21 | 6 ++--
drivers/hwmon/sht21.c | 92 +++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 94 insertions(+), 4 deletions(-)
diff --git a/Documentation/hwmon/sht21 b/Documentation/hwmon/sht21
index db17fda..a0db761 100644
--- a/Documentation/hwmon/sht21
+++ b/Documentation/hwmon/sht21
@@ -16,6 +16,7 @@ Supported chips:
Author:
Urs Fleisch <urs.fleisch@xxxxxxxxxxxxx>
+ Peter A. Bigot <pab@xxxxxxxxxxx>
Description
-----------
@@ -35,6 +36,7 @@ sysfs-Interface
temp1_input - temperature input
humidity1_input - humidity input
+eic1_input - Electronic Identification Code
Notes
-----
@@ -45,5 +47,5 @@ humidity and 66 ms for temperature. To keep self heating below 0.1 degree
Celsius, the device should not be active for more than 10% of the time,
e.g. maximum two measurements per second at the given resolution.
-Different resolutions, the on-chip heater, using the CRC checksum and reading
-the serial number are not supported yet.
+Different resolutions, the on-chip heater, and using the CRC checksum
+are not supported yet.
diff --git a/drivers/hwmon/sht21.c b/drivers/hwmon/sht21.c
index 84cdb1c..530350b 100644
--- a/drivers/hwmon/sht21.c
+++ b/drivers/hwmon/sht21.c
@@ -1,6 +1,7 @@
/* Sensirion SHT21 humidity and temperature sensor driver
*
* Copyright (C) 2010 Urs Fleisch <urs.fleisch@xxxxxxxxxxxxx>
+ * Copyright (C) 2016 Peter A. Bigot <pab@xxxxxxxxxxx>
*
* 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
@@ -35,6 +36,10 @@
#define SHT21_TRIG_T_MEASUREMENT_HM 0xe3
#define SHT21_TRIG_RH_MEASUREMENT_HM 0xe5
+/* Valid flags */
+#define SHT21_MEASUREMENT_VALID 0x01
+#define SHT21_EIC_VALID 0x02
+
/**
* struct sht21 - SHT21 device specific data
* @hwmon_dev: device registered with hwmon
@@ -43,6 +48,7 @@
* @last_update: time of last update (jiffies)
* @temperature: cached temperature measurement value
* @humidity: cached humidity measurement value
+ * @eic: cached electronic identification code
*/
struct sht21 {
struct i2c_client *client;
@@ -51,6 +57,7 @@ struct sht21 {
unsigned long last_update;
int temperature;
int humidity;
+ u8 eic[8];
};
/**
@@ -101,7 +108,8 @@ static int sht21_update_measurements(struct device *dev)
* 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) {
+ if (time_after(jiffies, sht21->last_update + HZ / 2)
+ || !(SHT21_MEASUREMENT_VALID & sht21->valid)) {
ret = i2c_smbus_read_word_swapped(client,
SHT21_TRIG_T_MEASUREMENT_HM);
if (ret < 0)
@@ -113,7 +121,7 @@ static int sht21_update_measurements(struct device *dev)
goto out;
sht21->humidity = sht21_rh_ticks_to_per_cent_mille(ret);
sht21->last_update = jiffies;
- sht21->valid = 1;
+ sht21->valid |= SHT21_MEASUREMENT_VALID;
}
out:
mutex_unlock(&sht21->lock);
@@ -165,15 +173,95 @@ static ssize_t sht21_show_humidity(struct device *dev,
return sprintf(buf, "%d\n", sht21->humidity);
}
+/**
+ * sht21_show_eic() - show Electronic Identification Code 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 eic1_input sysfs attribute.
+ * Returns number of bytes written into buffer, negative errno on error.
+ */
+static ssize_t sht21_show_eic(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct sht21 *sht21 = dev_get_drvdata(dev);
+ struct i2c_client *client = sht21->client;
+ int ret = 0;
+ int i;
+ char *bp = buf;
+ mutex_lock(&sht21->lock);
+ if (!(SHT21_EIC_VALID & sht21->valid)) {
+ u8 tx[4];
+ u8 rx[8];
+ struct i2c_msg msgs[2] = {
+ {
+ .addr = client->addr,
+ .flags = 0,
+ .len = 0,
+ .buf = tx,
+ },
+ {
+ .addr = client->addr,
+ .flags = I2C_M_RD,
+ .len = 0,
+ .buf = rx,
+ },
+ };
+ u8 *dp = tx;
+ *dp++ = 0xFA;
+ *dp++ = 0x0F;
+ msgs[0].len = dp-tx;
+ msgs[1].len = 8;
+ ret = i2c_transfer(client->adapter, msgs, 2);
+ if (ret < 0)
+ goto out;
+ sht21->eic[2] = rx[0];
+ sht21->eic[3] = rx[2];
+ sht21->eic[4] = rx[4];
+ sht21->eic[5] = rx[6];
+ dp = tx;
+ *dp++ = 0xFC;
+ *dp++ = 0xC9;
+ msgs[0].len = dp-tx;
+ msgs[1].len = 6;
+ ret = i2c_transfer(client->adapter, msgs, 2);
+ if (ret < 0)
+ goto out;
+ sht21->eic[0] = rx[3];
+ sht21->eic[1] = rx[4];
+ sht21->eic[6] = rx[0];
+ sht21->eic[7] = rx[1];
+ sht21->valid |= SHT21_EIC_VALID;
+ }
+
+ for (i = 0; i < sizeof(sht21->eic); ++i) {
+ ret = sprintf(bp, "%02x", sht21->eic[i]);
+ if (ret < 0)
+ goto out;
+ bp += ret;
+ }
+out:
+ mutex_unlock(&sht21->lock);
+ if (ret >= 0) {
+ *bp++ = '\n';
+ ret = bp - buf;
+ }
+ return ret;
+}
+
/* 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(eic1_input, S_IRUGO, sht21_show_eic, NULL, 0);
static struct attribute *sht21_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_humidity1_input.dev_attr.attr,
+ &sensor_dev_attr_eic1_input.dev_attr.attr,
NULL
};
--
2.7.4
--
To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
