hwmon: Add support for ltc2947
The ltc2947 is a high precision power and energy monitor with an
internal sense resistor supporting up to +/- 30A. Three internal no
Latency ADCs ensure accurate measurement of voltage and current, while
high-bandwidth analog multiplication of voltage and current provides
accurate power measurement in a wide range of applications. Internal or
external clocking options enable precise charge and energy measurements.
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20191021154115.319073-1-nuno.sa@analog.com
[groeck: Removed unnecessary checks when reading temperature and energy;
PAGE{0,1} -> LTC2947_PAGE_{0,1}]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
diff --git a/Documentation/hwmon/ltc2947.rst b/Documentation/hwmon/ltc2947.rst
new file mode 100644
index 0000000..419fc84
--- /dev/null
+++ b/Documentation/hwmon/ltc2947.rst
@@ -0,0 +1,100 @@
+Kernel drivers ltc2947-i2c and ltc2947-spi
+==========================================
+
+Supported chips:
+
+ * Analog Devices LTC2947
+
+ Prefix: 'ltc2947'
+
+ Addresses scanned: -
+
+ Datasheet:
+
+ https://www.analog.com/media/en/technical-documentation/data-sheets/LTC2947.pdf
+
+Author: Nuno Sá <nuno.sa@analog.com>
+
+Description
+___________
+
+The LTC2947 is a high precision power and energy monitor that measures current,
+voltage, power, temperature, charge and energy. The device supports both SPI
+and I2C depending on the chip configuration.
+The device also measures accumulated quantities as energy. It has two banks of
+register's to read/set energy related values. These banks can be configured
+independently to have setups like: energy1 accumulates always and enrgy2 only
+accumulates if current is positive (to check battery charging efficiency for
+example). The device also supports a GPIO pin that can be configured as output
+to control a fan as a function of measured temperature. Then, the GPIO becomes
+active as soon as a temperature reading is higher than a defined threshold. The
+temp2 channel is used to control this thresholds and to read the respective
+alarms.
+
+Sysfs entries
+_____________
+
+The following attributes are supported. Limits are read-write, reset_history
+is write-only and all the other attributes are read-only.
+
+======================= ==========================================
+in0_input VP-VM voltage (mV).
+in0_min Undervoltage threshold
+in0_max Overvoltage threshold
+in0_lowest Lowest measured voltage
+in0_highest Highest measured voltage
+in0_reset_history Write 1 to reset in1 history
+in0_min_alarm Undervoltage alarm
+in0_max_alarm Overvoltage alarm
+in0_label Channel label (VP-VM)
+
+in1_input DVCC voltage (mV)
+in1_min Undervoltage threshold
+in1_max Overvoltage threshold
+in1_lowest Lowest measured voltage
+in1_highest Highest measured voltage
+in1_reset_history Write 1 to reset in2 history
+in1_min_alarm Undervoltage alarm
+in1_max_alarm Overvoltage alarm
+in1_label Channel label (DVCC)
+
+curr1_input IP-IM Sense current (mA)
+curr1_min Undercurrent threshold
+curr1_max Overcurrent threshold
+curr1_lowest Lowest measured current
+curr1_highest Highest measured current
+curr1_reset_history Write 1 to reset curr1 history
+curr1_min_alarm Undercurrent alarm
+curr1_max_alarm Overcurrent alarm
+curr1_label Channel label (IP-IM)
+
+power1_input Power (in uW)
+power1_min Low power threshold
+power1_max High power threshold
+power1_input_lowest Historical minimum power use
+power1_input_highest Historical maximum power use
+power1_reset_history Write 1 to reset power1 history
+power1_min_alarm Low power alarm
+power1_max_alarm High power alarm
+power1_label Channel label (Power)
+
+temp1_input Chip Temperature (in milliC)
+temp1_min Low temperature threshold
+temp1_max High temperature threshold
+temp1_input_lowest Historical minimum temperature use
+temp1_input_highest Historical maximum temperature use
+temp1_reset_history Write 1 to reset temp1 history
+temp1_min_alarm Low temperature alarm
+temp1_max_alarm High temperature alarm
+temp1_label Channel label (Ambient)
+
+temp2_min Low temperature threshold for fan control
+temp2_max High temperature threshold for fan control
+temp2_min_alarm Low temperature fan control alarm
+temp2_max_alarm High temperature fan control alarm
+temp2_label Channel label (TEMPFAN)
+
+energy1_input Measured energy over time (in microJoule)
+
+energy2_input Measured energy over time (in microJoule)
+======================= ==========================================