diff options
Diffstat (limited to 'Documentation/ABI/testing/sysfs-driver-w1_therm')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-driver-w1_therm | 75 |
1 files changed, 51 insertions, 24 deletions
diff --git a/Documentation/ABI/testing/sysfs-driver-w1_therm b/Documentation/ABI/testing/sysfs-driver-w1_therm index 8873bbb075cb..6a37dc33ffdb 100644 --- a/Documentation/ABI/testing/sysfs-driver-w1_therm +++ b/Documentation/ABI/testing/sysfs-driver-w1_therm @@ -22,8 +22,10 @@ Description: device data to its embedded EEPROM, either restore data embedded in device EEPROM. Be aware that devices support limited EEPROM writing cycles (typical 50k) + * 'save': save device RAM to EEPROM * 'restore': restore EEPROM data in device RAM + Users: any user space application which wants to communicate with w1_term device @@ -33,9 +35,11 @@ Date: May 2020 Contact: Akira Shimahara <akira215corp@gmail.com> Description: (RO) return the power status by asking the device + * '0': device parasite powered * '1': device externally powered * '-xx': xx is kernel error when reading power status + Users: any user space application which wants to communicate with w1_term device @@ -49,10 +53,12 @@ Description: will be changed only in device RAM, so it will be cleared when power is lost. Trigger a 'save' to EEPROM command to keep values after power-on. Read or write are : + * '9..14': device resolution in bit - or resolution to set in bit + or resolution to set in bit * '-xx': xx is kernel error when reading the resolution * Anything else: do nothing + Some DS18B20 clones are fixed in 12-bit resolution, so the actual resolution is read back from the chip and verified. Error is reported if the results differ. @@ -65,16 +71,18 @@ Date: May 2020 Contact: Akira Shimahara <akira215corp@gmail.com> Description: (RO) return the temperature in 1/1000 degC. + * If a bulk read has been triggered, it will directly - return the temperature computed when the bulk read - occurred, if available. If not yet available, nothing - is returned (a debug kernel message is sent), you - should retry later on. + return the temperature computed when the bulk read + occurred, if available. If not yet available, nothing + is returned (a debug kernel message is sent), you + should retry later on. * If no bulk read has been triggered, it will trigger - a conversion and send the result. Note that the - conversion duration depend on the resolution (if - device support this feature). It takes 94ms in 9bits - resolution, 750ms for 12bits. + a conversion and send the result. Note that the + conversion duration depend on the resolution (if + device support this feature). It takes 94ms in 9bits + resolution, 750ms for 12bits. + Users: any user space application which wants to communicate with w1_term device @@ -86,12 +94,14 @@ Description: (RW) return the temperature in 1/1000 degC. *read*: return 2 lines with the hexa output data sent on the bus, return the CRC check and temperature in 1/1000 degC - *write* : + *write*: + * '0' : save the 2 or 3 bytes to the device EEPROM - (i.e. TH, TL and config register) + (i.e. TH, TL and config register) * '9..14' : set the device resolution in RAM - (if supported) + (if supported) * Anything else: do nothing + refer to Documentation/w1/slaves/w1_therm.rst for detailed information. Users: any user space application which wants to communicate with @@ -103,14 +113,21 @@ Date: May 2020 Contact: Akira Shimahara <akira215corp@gmail.com> Description: (RW) trigger a bulk read conversion. read the status + *read*: - * '-1': conversion in progress on at least 1 sensor - * '1' : conversion complete but at least one sensor + * '-1': + conversion in progress on at least 1 sensor + * '1' : + conversion complete but at least one sensor value has not been read yet - * '0' : no bulk operation. Reading temperature will + * '0' : + no bulk operation. Reading temperature will trigger a conversion on each device - *write*: 'trigger': trigger a bulk read on all supporting + + *write*: + 'trigger': trigger a bulk read on all supporting devices on the bus + Note that if a bulk read is sent but one sensor is not read immediately, the next access to temperature on this device will return the temperature measured at the time of issue @@ -128,14 +145,19 @@ Description: reset to default (datasheet) conversion time for a new resolution. - *read*: Actual conversion time in milliseconds. *write*: - '0': Set the default conversion time from the datasheet. - '1': Measure and set the conversion time. Make a single + *read*: + Actual conversion time in milliseconds. + + *write*: + * '0': + Set the default conversion time from the datasheet. + * '1': + Measure and set the conversion time. Make a single temperature conversion, measure an actual value. Increase it by 20% for temperature range. A new conversion time can be obtained by reading this same attribute. - other positive value: + * other positive value: Set the conversion time in milliseconds. Users: An application using the w1_term device @@ -148,16 +170,21 @@ Description: (RW) Control optional driver settings. Bit masks to read/write (bitwise OR): - 1: Enable check for conversion success. If byte 6 of + == ============================================================ + 1 Enable check for conversion success. If byte 6 of scratchpad memory is 0xC after conversion, and temperature reads 85.00 (powerup value) or 127.94 (insufficient power) - return a conversion error. - 2: Enable poll for conversion completion. Generate read cycles + 2 Enable poll for conversion completion. Generate read cycles after the conversion start and wait for 1's. In parasite power mode this feature is not available. + == ============================================================ + + *read*: + Currently selected features. - *read*: Currently selected features. - *write*: Select features. + *write*: + Select features. Users: An application using the w1_term device |