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authorDaniel Matyas <daniel.matyas@analog.com>2023-10-31 21:21:57 +0300
committerGuenter Roeck <linux@roeck-us.net>2023-12-11 17:42:58 +0300
commit29a9ac6414abd634e7f460a250b70a452d9a04b9 (patch)
tree1c21f26532c296844bcfdf7323763abcd3b22730 /Documentation/hwmon
parent64176bde4645686590bb0e5efcbcd18497ee4389 (diff)
downloadlinux-29a9ac6414abd634e7f460a250b70a452d9a04b9.tar.xz
hwmon: (max31827) Add custom attribute for resolution
Added custom channel-specific (temp1) attribute for resolution. The wait time for a conversion in one-shot mode (enable = 0) depends on the resolution. When resolution is 12-bit, the conversion time is 140ms, but the minimum update_interval is 125ms. Handled this problem by waiting an additional 15ms (125ms + 15ms = 140ms). Added 'mask' parameter to the shutdown_write() function. Now it can either write or update bits, depending on the value of mask. This is needed, because for alarms a write is necessary, but for resolution only the resolution bits should be updated. Signed-off-by: Daniel Matyas <daniel.matyas@analog.com> Link: https://lore.kernel.org/r/20231031182158.124608-5-daniel.matyas@analog.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Diffstat (limited to 'Documentation/hwmon')
-rw-r--r--Documentation/hwmon/max31827.rst29
1 files changed, 23 insertions, 6 deletions
diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
index a8bbfb85dd02..44ab9dc064cb 100644
--- a/Documentation/hwmon/max31827.rst
+++ b/Documentation/hwmon/max31827.rst
@@ -90,11 +90,28 @@ the data sheet are:
Enabling the device when it is already enabled has the side effect of setting
the conversion frequency to 1 conv/s. The conversion time varies depending on
-the resolution. The conversion time doubles with every bit of increased
-resolution. For 10 bit resolution 35ms are needed, while for 12 bit resolution
-(default) 140ms. When chip is in shutdown mode and a read operation is
-requested, one-shot is triggered, the device waits for 140 (conversion time) ms,
-and only after that is the temperature value register read.
+the resolution.
+
+The conversion time doubles with every bit of increased resolution. The
+available resolutions are:
+
+- 8 bit -> 8.75 ms conversion time
+- 9 bit -> 17.5 ms conversion time
+- 10 bit -> 35 ms conversion time
+- 12 bit (default) -> 140 ms conversion time
+
+There is a temp1_resolution attribute which indicates the unit change in the
+input temperature in milli-degrees C.
+
+- 1000 mC -> 8 bit
+- 500 mC -> 9 bit
+- 250 mC -> 10 bit
+- 62 mC -> 12 bit (default) - actually this is 62.5, but the fil returns 62
+
+When chip is in shutdown mode and a read operation is requested, one-shot is
+triggered, the device waits for <conversion time> ms, and only after that is
+the temperature value register read. Note that the conversion times are rounded
+up to the nearest possible integer.
The LSB of the temperature values is 0.0625 degrees Celsius, but the values of
the temperatures are displayed in milli-degrees. This means, that some data is
@@ -117,4 +134,4 @@ corresponding status bits.
Notes
-----
-PEC and resolution are not implemented.
+PEC is not implemented.