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| author | Akira Shimahara <akira215corp@gmail.com> | 2020-05-11 23:38:20 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-05-15 17:29:00 +0300 |
| commit | 57c76221d5af648c8355a55c09b050c5d8d38189 (patch) | |
| tree | 7b07dd6dbd2a5d8b42247b778ceeccb348f083da /Documentation/ABI/testing/sysfs-driver-w1_therm | |
| parent | e2c94d6f572079511945e64537eb1218643f2e68 (diff) | |
| download | linux-57c76221d5af648c8355a55c09b050c5d8d38189.tar.xz | |
w1_therm: adding bulk read support to trigger multiple conversion on bus
Adding bulk read support:
Sending a 'trigger' command in the dedicated sysfs entry of bus master
device send a conversion command for all the slaves on the bus. The sysfs
entry is added as soon as at least one device supporting this feature
is detected on the bus.
The behavior of the sysfs reading temperature on the device is as follow:
* If no bulk read pending, trigger a conversion on the device, wait for
the conversion to be done, read the temperature in device RAM
* If a bulk read has been trigger, access directly the device RAM
This behavior is the same on the 2 sysfs entries ('temperature' and
'w1_slave').
Reading the therm_bulk_read sysfs give the status of bulk operations:
* '-1': conversion in progress on at least 1 sensor
* '1': conversion complete but at least one sensor has not been read yet
* '0': no bulk operation. Reading temperature on ecah device will trigger
a conversion
As not all devices support bulk read feature, it has been added in device
family structure.
The attribute is set at master level as soon as a supporting device is
discover. It is removed when the last supported device leave the bus.
The count of supported device is kept with the static counter
bulk_read_device_counter.
A strong pull up is apply on the line if at least one device required it.
The duration of the pull up is the max time required by a device on the
line, which depends on the resolution settings of each device. The strong
pull up could be adjust with the a module parameter.
Updating documentation in Documentation/ABI/testing/sysfs-driver-w1_therm
and Documentation/w1/slaves/w1_therm.rst accordingly.
Signed-off-by: Akira Shimahara <akira215corp@gmail.com>
Link: https://lore.kernel.org/r/20200511203820.411483-1-akira215corp@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/ABI/testing/sysfs-driver-w1_therm')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-driver-w1_therm | 36 |
1 files changed, 32 insertions, 4 deletions
diff --git a/Documentation/ABI/testing/sysfs-driver-w1_therm b/Documentation/ABI/testing/sysfs-driver-w1_therm index f2895205a515..076659d506f2 100644 --- a/Documentation/ABI/testing/sysfs-driver-w1_therm +++ b/Documentation/ABI/testing/sysfs-driver-w1_therm @@ -62,9 +62,16 @@ Date: May 2020 Contact: Akira Shimahara <akira215corp@gmail.com> Description: (RO) return the temperature in 1/1000 degC. - Note that the conversion duration depend on the resolution (if - device support this feature). It takes 94ms in 9bits - resolution, 750ms for 12bits. + * 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. + * 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. Users: any user space application which wants to communicate with w1_term device @@ -85,4 +92,25 @@ Description: refer to Documentation/w1/slaves/w1_therm.rst for detailed information. Users: any user space application which wants to communicate with - w1_term device
\ No newline at end of file + w1_term device + + +What: /sys/bus/w1/devices/w1_bus_masterXX/therm_bulk_read +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 + value has not been read yet + * '0' : no bulk operation. Reading temperature will + trigger a conversion on each device + *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 + of the bulk read command (not the current temperature). +Users: any user space application which wants to communicate with + w1_term device |