Content-Disposition: inline; filename=hwmon-sysfs-interface-update-2.patch Reword and complete certain parts of the hwmon sysfs-interface documentation file. Hopefully this will make things clearer for new driver authors. Signed-off-by: Jean Delvare <khali at linux-fr.org> --- Documentation/hwmon/sysfs-interface | 39 +++++++++++++++++++++++------------ 1 file changed, 26 insertions(+), 13 deletions(-) --- linux-2.6.17-rc5.orig/Documentation/hwmon/sysfs-interface 2006-06-04 09:05:52.000000000 +0200 +++ linux-2.6.17-rc5/Documentation/hwmon/sysfs-interface 2006-06-04 09:16:38.000000000 +0200 @@ -3,7 +3,7 @@ The libsensors library offers an interface to the raw sensors data through the sysfs interface. See libsensors documentation and source for -more further information. As of writing this document, libsensors +further information. As of writing this document, libsensors (from lm_sensors 2.8.3) is heavily chip-dependant. Adding or updating support for any given chip requires modifying the library's code. This is because libsensors was written for the procfs interface @@ -39,15 +39,16 @@ this standard. Note that this standard isn't completely established yet, so it is subject -to changes, even important ones. One more reason to use the library instead -of accessing sysfs files directly. +to changes. If you are writing a new hardware monitoring driver those +features can't seem to fit in this interface, please contact us with your +extension proposal. Keep in mind that backward compatibility must be +preserved. Each chip gets its own directory in the sysfs /sys/devices tree. To -find all sensor chips, it is easier to follow the symlinks from -/sys/i2c/devices/ +find all sensor chips, it is easier to follow the device symlinks from +/sys/class/hwmon/hwmon*. -All sysfs values are fixed point numbers. To get the true value of some -of the values, you should divide by the specified value. +All sysfs values are fixed point numbers. There is only one value per file, unlike the older /proc specification. The common scheme for files naming is: <type><number>_<item>. Usual @@ -77,6 +78,9 @@ Read/write values may be read-only for some chips, depending on the hardware implementation. +All entries are optional, and should only be created in a given driver +if the chip has the feature. + ************ * Voltages * ************ @@ -213,32 +217,32 @@ Not all types are supported by all chips temp[1-*]_max Temperature max value. - Unit: millidegree Celcius + Unit: millidegree Celsius (or millivolt, see below) RW temp[1-*]_min Temperature min value. - Unit: millidegree Celcius + Unit: millidegree Celsius RW temp[1-*]_max_hyst Temperature hysteresis value for max limit. - Unit: millidegree Celcius + Unit: millidegree Celsius Must be reported as an absolute temperature, NOT a delta from the max value. RW temp[1-*]_input Temperature input value. - Unit: millidegree Celcius + Unit: millidegree Celsius RO temp[1-*]_crit Temperature critical value, typically greater than corresponding temp_max values. - Unit: millidegree Celcius + Unit: millidegree Celsius RW temp[1-*]_crit_hyst Temperature hysteresis value for critical limit. - Unit: millidegree Celcius + Unit: millidegree Celsius Must be reported as an absolute temperature, NOT a delta from the critical value. RW @@ -256,6 +260,15 @@ itself, for example the thermal diode inside the CPU or a thermistor nearby. +Some chips measure temperature using external thermistors and an ADC, and +report the temperature measurement as a voltage. Converting this voltage +back to a temperature (or the other way around for limits) requires +mathematical functions not available in the kernel, so the conversion +must occur in user space. For these chips, all temp* files described +above should contain values expressed in millivolt instead of millidegree +Celsius. In other words, such temperature channels are handled as voltage +channels by the driver. + Also see the Alarms section for status flags associated with temperatures. -- Jean Delvare
