hwmon: (max31827) Handle new properties from the devicetree

Used fwnode to retrieve data from the devicetree in the init_client
function.

If the uint32 properties are not present, the default values are used
for max31827 chip.

Signed-off-by: Daniel Matyas <daniel.matyas@analog.com>
Link: https://lore.kernel.org/r/20231031182158.124608-1-daniel.matyas@analog.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 39 insertions, 9 deletions

diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
index 9a1055a007cf..a8bbfb85dd02 100644
--- a/Documentation/hwmon/max31827.rst
+++ b/Documentation/hwmon/max31827.rst
@@ -52,13 +52,21 @@ MAX31827 has low and over temperature alarms with an effective value and a
 hysteresis value: -40 and -30 degrees for under temperature alarm and +100 and
 +90 degrees for over temperature alarm.
 
-The alarm can be configured in comparator and interrupt mode. Currently only
-comparator mode is implemented. In Comparator mode, the OT/UT status bits have a
-value of 1 when the temperature rises above the TH value or falls below TL,
-which is also subject to the Fault Queue selection. OT status returns to 0 when
-the temperature drops below the TH_HYST value or when shutdown mode is entered.
-Similarly, UT status returns to 0 when the temperature rises above TL_HYST value
-or when shutdown mode is entered.
+The alarm can be configured in comparator and interrupt mode from the
+devicetree. In Comparator mode, the OT/UT status bits have a value of 1 when the
+temperature rises above the TH value or falls below TL, which is also subject to
+the Fault Queue selection. OT status returns to 0 when the temperature drops
+below the TH_HYST value or when shutdown mode is entered. Similarly, UT status
+returns to 0 when the temperature rises above TL_HYST value or when shutdown
+mode is entered.
+
+In interrupt mode exceeding TH also sets OT status to 1, which remains set until
+a read operation is performed on the configuration/status register (max or min
+attribute); at this point, it returns to 0. Once OT status is set to 1 from
+exceeding TH and reset, it is set to 1 again only when the temperature drops
+below TH_HYST. The output remains asserted until it is reset by a read. It is
+set again if the temperature rises above TH, and so on. The same logic applies
+to the operation of the UT status bit.
 
 Putting the MAX31827 into shutdown mode also resets the OT/UT status bits. Note
 that if the mode is changed while OT/UT status bits are set, an OT/UT status
@@ -68,6 +76,18 @@ clear the status bits before changing the operating mode.
 
 The conversions can be manual with the one-shot functionality and automatic with
 a set frequency. When powered on, the chip measures temperatures with 1 conv/s.
+The conversion rate can be modified with update_interval attribute of the chip.
+Conversion/second = 1/update_interval. Thus, the available options according to
+the data sheet are:
+
+- 64000 (ms) = 1 conv/64 sec
+- 32000 (ms) = 1 conv/32 sec
+- 16000 (ms) = 1 conv/16 sec
+- 4000 (ms) = 1 conv/4 sec
+- 1000 (ms) = 1 conv/sec (default)
+- 250 (ms) = 4 conv/sec
+- 125 (ms) = 8 conv/sec
+
 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
@@ -83,8 +103,18 @@ in the writing of alarm values too. For positive numbers the user-input value
 will always be rounded down to the nearest possible value, for negative numbers
 the user-input will always be rounded up to the nearest possible value.
 
+Bus timeout resets the I2C-compatible interface when SCL is low for more than
+30ms (nominal).
+
+Alarm polarity determines if the active state of the alarm is low or high. The
+behavior for both settings is dependent on the Fault Queue setting. The ALARM
+pin is an open-drain output and requires a pullup resistor to operate.
+
+The Fault Queue bits select how many consecutive temperature faults must occur
+before overtemperature or undertemperature faults are indicated in the
+corresponding status bits.
+
 Notes
 -----
 
-Currently fault queue, alarm polarity and resolution cannot be modified.
-PEC is not implemented either.
+PEC and resolution are not implemented.