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SubjectRe: [PATCH v2 1/2] Changes in w1_therm.c and adding w1_therm.h
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Date
Le dimanche 26 avril 2020 à 19:09 +0200, Greg KH a écrit :
> On Sun, Apr 26, 2020 at 02:36:52PM +0200, Akira shimahara wrote:
> > Le dimanche 26 avril 2020 à 09:51 +0200, Greg KH a écrit :
> > > On Sat, Apr 25, 2020 at 05:31:41PM +0200, Akira Shimahara wrote:
> > > > From: Akira SHIMAHARA <akira215corp@gmail.com>
> > > >
> > > > Patch for enhacement of w1_therm module. Added features :
> > > > - Bulk read : send one command for all the slaves
> > > > on the bus to trigger temperature conversion
> > > > - Optimized conversion time regarding to device resolution
> > > > - Dedicated sysfs entry for powering read,
> > > > resolution set/get, eeprom save/restore
> > > > - Alarms settings and reading
> > > > - Code optimization to mitigate bus traffic
> > > > (devices information are stored to avoid
> > > > interrogating each device every-time)
> > > >
> > > > Following sysfs entry are added :
> > > > - temperature (RO) : return the temperature in 1/1000°
> > > > - ext_power (RO) : return the power status of the device
> > > > - resolution (RW) : get or set the device resolution
> > > > (supported
> > > > devices)
> > > > - eeprom (WO) :trigger a save or restore to/from device EEPROM
> > > > - alarms (RW) : read or write TH and TL in the device RAM
> > > > - therm_bulk_read (RW) : Attribute at master level to trigger
> > > > bulk read and to survey the progress of devices
> > > > conversions
> > > > - w1_slave has been kept for compatibility
> > > >
> > > > Main motivation was to improve temperature reading speed, which
> > > > depend
> > > > on resolution settings of devices. The module store the powwer
> > > > status and
> > > > the resolution of each device so that during reading operation,
> > > > no
> > > > transaction is required on the bus, which improve speed.
> > > > The hardware status is checked as soon as a new device is
> > > > detected,
> > > > when a user change occurred, or when the corresponding sys file
> > > > is
> > > > accessed by user.
> > > >
> > > > The bulk read allow to trigger convserion of all devices on the
> > > > bus
> > > > at
> > > > the same time. It will apply a strong pull up 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.
> > > >
> > > > Please let me know any feedback you have on this patch.
> > > >
> > > > Thanks ahead,
> > > >
> > > > Signed-off-by: Akira Shimahara <akira215corp@gmail.com>
> > > > ---
> > > > Changes in v2:
> > > > - Adding documentation in Documentatin/ABI/testing/sysfs-
> > > > driver-
> > > > w1_therm
> > > > - Updating existing documentation in
> > > > Documentation/w1/slaves/w1_therm.rst
> > > >
> > > > drivers/w1/slaves/w1_therm.c | 1406
> > > > ++++++++++++++++++++++++++--
> > > > ------
> > > > drivers/w1/slaves/w1_therm.h | 386 ++++++++++
> > > > 2 files changed, 1470 insertions(+), 322 deletions(-)
> > > > create mode 100644 drivers/w1/slaves/w1_therm.h
> > >
> > > No documentation files are added here :(
> > >
> >
> > It's in the PATCH 2/2 included in the previous mail. You want me to
> > merge in one commit ?. I thought it was easier for you to keep a
> > track
> > of the v1.
>
> What previous mail? I don't see a patch 2/2 here, did you not cc:
> me?
>
> thanks,
>
> greg kh

I'm so sorry Greg, I made a mistake. Please find hereby the patch 2/2.
Let me know if you want me to merge into 1 commit.

Thanks,

Akira SHIMAHARA

From 084addf560b771b54c2f977904f2139f818ecca7 Mon Sep 17 00:00:00 2001
From: Akira SHIMAHARA <akira215corp@gmail.com>
Date: Sat, 25 Apr 2020 16:30:45 +0200
Subject: [PATCH v2 2/2] w1_therm documentation

* updating w1_therm.rst documentation

* adding sysfs-driver-w1_therm documentation

Signed-off-by: Akira Shimahara <akira215corp@gmail.com>
---
Changes in v2:
- Adding documentation in Documentatin/ABI/testing/sysfs-driver-
w1_therm
- Updating existing documentation in
Documentation/w1/slaves/w1_therm.rst

.../ABI/testing/sysfs-driver-w1_therm | 115 ++++++++++++++++++
Documentation/w1/slaves/w1_therm.rst | 52 ++++++--
2 files changed, 157 insertions(+), 10 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-driver-w1_therm

diff --git a/Documentation/ABI/testing/sysfs-driver-w1_therm
b/Documentation/ABI/testing/sysfs-driver-w1_therm
new file mode 100644
index 0000000000000..e18261189684c
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-w1_therm
@@ -0,0 +1,115 @@
+What: /sys/bus/w1/devices/.../alarms
+Date: Apr 2020
+Contact: Akira Shimahara <akira215corp@gmail.com>
+Description:
+ (RW) read or write TH and TL (Temperature High an Low)
alarms.
+ Values shall be space separated and in the device range
+ (typical -55 degC to 125 degC). Values are integer as
they
+ are store in a 8bit register in the device.
+ Lowest value is automatically put to TL.
+ Once set, alarms could be search at master level, refer
to
+ Documentation/w1/w1_generic.rst for detailed
information
+Users: any user space application which wants to communicate
with
+ w1_term device
+
+
+What: /sys/bus/w1/devices/.../eeprom
+Date: Apr 2020
+Contact: Akira Shimahara <akira215corp@gmail.com>
+Description:
+ (WO) writing that file will either trigger a save of
the
+ 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
+
+
+What: /sys/bus/w1/devices/.../ext_power
+Date: Apr 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
+
+
+What: /sys/bus/w1/devices/.../resolution
+Date: Apr 2020
+Contact: Akira Shimahara <akira215corp@gmail.com>
+Description:
+ (RW) get or set the device resolution (on supported
devices,
+ if not, this entry is not present). Note that the
resolution
+ 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..12`: device resolution in bit
+ or resolution to set in bit
+ * `-xx`: xx is kernel error when reading the
resolution
+ * Anything else: do nothing
+Users: any user space application which wants to communicate
with
+ w1_term device
+
+
+What: /sys/bus/w1/devices/.../temperature
+Date: Apr 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.
+ * 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
+
+
+What: /sys/bus/w1/devices/.../w1_slave
+Date: Apr 2020
+Contact: Akira Shimahara <akira215corp@gmail.com>
+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* :
+ * `0` : save the 2 or 3 bytes to the device
EEPROM
+ (i.e. TH, TL and config register)
+ * `9..12` : set the device resolution in RAM
+ (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
+ w1_term device
+
+
+What: /sys/bus/w1/devices/w1_bus_masterXX/therm_bulk_read
+Date: Apr 2020
+Contact: Akira Shimahara <akira215corp@gmail.com>
+Description:
+ (RW) return the temperature in 1/1000 degC.
+ *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
diff --git a/Documentation/w1/slaves/w1_therm.rst
b/Documentation/w1/slaves/w1_therm.rst
index 90531c340a07a..06eaff1a05c08 100644
--- a/Documentation/w1/slaves/w1_therm.rst
+++ b/Documentation/w1/slaves/w1_therm.rst
@@ -26,20 +26,31 @@ W1_THERM_DS1825 0x3B
W1_THERM_DS28EA00 0x42
==================== ====

-Support is provided through the sysfs w1_slave file. Each open and
+Support is provided through the sysfs w1_slave file. Each open and
read sequence will initiate a temperature conversion then provide two
-lines of ASCII output. The first line contains the nine hex bytes
+lines of ASCII output. The first line contains the nine hex bytes
read along with a calculated crc value and YES or NO if it matched.
-If the crc matched the returned values are retained. The second line
+If the crc matched the returned values are retained. The second line
displays the retained values along with a temperature in millidegrees
Centigrade after t=.

-Parasite powered devices are limited to one slave performing a
-temperature conversion at a time. If none of the devices are parasite
-powered it would be possible to convert all the devices at the same
-time and then go back to read individual sensors. That isn't
-currently supported. The driver also doesn't support reduced
-precision (which would also reduce the conversion time) when reading
values.
+Alternatively, temperature can be read using temperature sysfs, it
+return only temperature in millidegrees Centigrade.
+
+A bulk read of all devices on the bus could be done writing 'trigger'
+in the therm_bulk_read sysfs entry at w1_bus_master level. This will
+sent the convert command on all devices on the bus, and if parasite
+powered devices are detected on the bus (and strong pullup is enable
+in the module), it will drive the line high during the longer
conversion
+time required by parasited powered device on the line. Reading
+therm_bulk_read will return 0 if no bulk conversion pending,
+-1 if at least one sensor still in conversion, 1 if conversion is
complete
+but at least one sensor value has not been read yet. Result
temperature is
+then accessed by reading the temperature sysfs entry of each device,
which
+may return empty if conversion is still in progress. 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).

Writing a value between 9 and 12 to the sysfs w1_slave file will
change the
precision of the sensor for the next readings. This value is in
(volatile)
@@ -49,6 +60,27 @@ To store the current precision configuration into
EEPROM, the value 0
has to be written to the sysfs w1_slave file. Since the EEPROM has a
limited
amount of writes (>50k), this command should be used wisely.

+Alternatively, resolution can be set or read (value from 9 to 12)
using the
+dedicated resolution sysfs entry on each device. This sysfs entry is
not
+present for devices not supporting this feature. Driver will adjust
the
+correct conversion time for each device regarding to its resolution
setting.
+In particular, strong pullup will be applied if required during the
conversion
+duration.
+
+The write-only sysfs entry eeprom is an alternative for EEPROM
operations:
+ * `save`: will save device RAM to EEPROM
+ * `restore`: will restore EEPROM data in device RAM.
+
+ext_power syfs entry allow tho check the power status of each device.
+ * `0`: device parasite powered
+ * `1`: device externally powered
+
+sysfs alarms allow read or write TH and TL (Temperature High an Low)
alarms.
+Values shall be space separated and in the device range (typical -55
degC
+to 125 degC). Values are integer as they are store in a 8bit register
in
+the device. Lowest value is automatically put to TL.Once set, alarms
could
+be search at master level.
+
The module parameter strong_pullup can be set to 0 to disable the
strong pullup, 1 to enable autodetection or 2 to force strong pullup.
In case of autodetection, the driver will use the "READ POWER SUPPLY"
@@ -71,4 +103,4 @@ detection algorithm. This feature allows you to
determine the physical
location of the chip in the 1-wire bus without needing pre-existing
knowledge of the bus ordering. Support is provided through the sysfs
w1_seq file. The file will contain a single line with an integer
value
-representing the device index in the bus starting at 0.
+representing the device index in the bus starting at 0.
\ No newline at end of file
\
 
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