diff options
| -rw-r--r-- | Documentation/hwmon/sht21 | 5 | ||||
| -rw-r--r-- | drivers/hwmon/sht21.c | 92 |
2 files changed, 93 insertions, 4 deletions
diff --git a/Documentation/hwmon/sht21 b/Documentation/hwmon/sht21 index db17fda45c3e..47f4765db256 100644 --- a/Documentation/hwmon/sht21 +++ b/Documentation/hwmon/sht21 @@ -35,6 +35,7 @@ sysfs-Interface temp1_input - temperature input humidity1_input - humidity input +eic - Electronic Identification Code Notes ----- @@ -45,5 +46,5 @@ 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 84cdb1cf0fb4..06706d288355 100644 --- a/drivers/hwmon/sht21.c +++ b/drivers/hwmon/sht21.c @@ -34,23 +34,29 @@ /* I2C command bytes */ #define SHT21_TRIG_T_MEASUREMENT_HM 0xe3 #define SHT21_TRIG_RH_MEASUREMENT_HM 0xe5 +#define SHT21_READ_SNB_CMD1 0xFA +#define SHT21_READ_SNB_CMD2 0x0F +#define SHT21_READ_SNAC_CMD1 0xFC +#define SHT21_READ_SNAC_CMD2 0xC9 /** * struct sht21 - SHT21 device specific data * @hwmon_dev: device registered with hwmon * @lock: mutex to protect measurement values - * @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 + * @valid: only 0 before first measurement is taken + * @eic: cached electronic identification code text */ struct sht21 { struct i2c_client *client; struct mutex lock; - char valid; unsigned long last_update; int temperature; int humidity; + char valid; + char eic[18]; }; /** @@ -165,15 +171,97 @@ static ssize_t sht21_show_humidity(struct device *dev, return sprintf(buf, "%d\n", sht21->humidity); } +static ssize_t eic_read(struct sht21 *sht21) +{ + struct i2c_client *client = sht21->client; + u8 tx[2]; + u8 rx[8]; + u8 eic[8]; + struct i2c_msg msgs[2] = { + { + .addr = client->addr, + .flags = 0, + .len = 2, + .buf = tx, + }, + { + .addr = client->addr, + .flags = I2C_M_RD, + .len = 8, + .buf = rx, + }, + }; + int ret; + + tx[0] = SHT21_READ_SNB_CMD1; + tx[1] = SHT21_READ_SNB_CMD2; + ret = i2c_transfer(client->adapter, msgs, 2); + if (ret < 0) + goto out; + eic[2] = rx[0]; + eic[3] = rx[2]; + eic[4] = rx[4]; + eic[5] = rx[6]; + + tx[0] = SHT21_READ_SNAC_CMD1; + tx[1] = SHT21_READ_SNAC_CMD2; + msgs[1].len = 6; + ret = i2c_transfer(client->adapter, msgs, 2); + if (ret < 0) + goto out; + eic[0] = rx[3]; + eic[1] = rx[4]; + eic[6] = rx[0]; + eic[7] = rx[1]; + + ret = snprintf(sht21->eic, sizeof(sht21->eic), + "%02x%02x%02x%02x%02x%02x%02x%02x\n", + eic[0], eic[1], eic[2], eic[3], + eic[4], eic[5], eic[6], eic[7]); +out: + if (ret < 0) + sht21->eic[0] = 0; + + return ret; +} + +/** + * eic_show() - show Electronic Identification Code in sysfs + * @dev: device + * @attr: device attribute + * @buf: sysfs buffer (PAGE_SIZE) where EIC is written + * + * Will be called on read access to eic sysfs attribute. + * Returns number of bytes written into buffer, negative errno on error. + */ +static ssize_t eic_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sht21 *sht21 = dev_get_drvdata(dev); + int ret; + + ret = sizeof(sht21->eic) - 1; + mutex_lock(&sht21->lock); + if (!sht21->eic[0]) + ret = eic_read(sht21); + if (ret > 0) + memcpy(buf, sht21->eic, ret); + mutex_unlock(&sht21->lock); + 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 DEVICE_ATTR_RO(eic); static struct attribute *sht21_attrs[] = { &sensor_dev_attr_temp1_input.dev_attr.attr, &sensor_dev_attr_humidity1_input.dev_attr.attr, + &dev_attr_eic.attr, NULL }; |