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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-08-07 13:11:27 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-08-07 13:11:27 +0000
commit34996e42f82bfd60bc2c191e5cae3c6ab233ec6c (patch)
tree62db60558cbf089714b48daeabca82bf2b20b20e /Documentation/hwmon/ltc4282.rst
parentAdding debian version 6.8.12-1. (diff)
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Merging upstream version 6.9.7.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel drivers ltc4282
+==========================================
+
+Supported chips:
+
+ * Analog Devices LTC4282
+
+ Prefix: 'ltc4282'
+
+ Addresses scanned: - I2C 0x40 - 0x5A (7-bit)
+ Addresses scanned: - I2C 0x80 - 0xB4 with a step of 2 (8-bit)
+
+ Datasheet:
+
+ https://www.analog.com/media/en/technical-documentation/data-sheets/ltc4282.pdf
+
+Author: Nuno Sá <nuno.sa@analog.com>
+
+Description
+___________
+
+The LTC4282 hot swap controller allows a board to be safely inserted and removed
+from a live backplane. Using one or more external N-channel pass transistors,
+board supply voltage and inrush current are ramped up at an adjustable rate. An
+I2C interface and onboard ADC allows for monitoring of board current, voltage,
+power, energy and fault status. The device features analog foldback current
+limiting and supply monitoring for applications from 2.9V to 33V. Dual 12V gate
+drive allows high power applications to either share safe operating area across
+parallel MOSFETs or support a 2-stage start-up that first charges the load
+capacitance followed by enabling a low on-resistance path to the load. The
+LTC4282 is well suited to high power applications because the precise monitoring
+capability and accurate current limiting reduce the extremes in which both loads
+and power supplies must safely operate. Non-volatile configuration allows for
+flexibility in the autonomous generation of alerts and response to faults.
+
+Sysfs entries
+_____________
+
+The following attributes are supported. Limits are read-write and all the other
+attributes are read-only. Note that in0 and in1 are mutually exclusive. Enabling
+one disables the other and disabling one enables the other.
+
+======================= ==========================================
+in0_input Output 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 in0 history.
+ Also clears fet bad and short fault logs.
+in0_min_alarm Undervoltage alarm
+in0_max_alarm Overvoltage alarm
+in0_enable Enable/Disable VSOURCE monitoring
+in0_fault Failure in the MOSFETs. Either bad or shorted FET.
+in0_label Channel label (VSOURCE)
+
+in1_input Input 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 in1 history.
+ Also clears over/undervoltage fault logs.
+in1_min_alarm Undervoltage alarm
+in1_max_alarm Overvoltage alarm
+in1_lcrit_alarm Critical Undervoltage alarm
+in1_crit_alarm Critical Overvoltage alarm
+in1_enable Enable/Disable VDD monitoring
+in1_label Channel label (VDD)
+
+in2_input GPIO voltage (mV)
+in2_min Undervoltage threshold
+in2_max Overvoltage threshold
+in2_lowest Lowest measured voltage
+in2_highest Highest measured voltage
+in2_reset_history Write 1 to reset in2 history
+in2_min_alarm Undervoltage alarm
+in2_max_alarm Overvoltage alarm
+in2_label Channel label (VGPIO)
+
+curr1_input 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.
+ Also clears overcurrent fault logs.
+curr1_min_alarm Undercurrent alarm
+curr1_max_alarm Overcurrent alarm
+curr1_crit_alarm Critical Overcurrent alarm
+curr1_label Channel label (ISENSE)
+
+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.
+ Also clears power bad fault logs.
+power1_min_alarm Low power alarm
+power1_max_alarm High power alarm
+power1_label Channel label (Power)
+
+energy1_input Measured energy over time (in microJoule)
+energy1_enable Enable/Disable Energy accumulation
+======================= ==========================================
+
+DebugFs entries
+_______________
+
+The chip also has a fault log register where failures can be logged. Hence,
+as these are logging events, we give access to them in debugfs. Note that
+even if some failure is detected in these logs, it does necessarily mean
+that the failure is still present. As mentioned in the proper Sysfs entries,
+these logs can be cleared by writing in the proper reset_history attribute.
+
+.. warning:: The debugfs interface is subject to change without notice
+ and is only available when the kernel is compiled with
+ ``CONFIG_DEBUG_FS`` defined.
+
+``/sys/kernel/debug/ltc4282-hwmon[X]/``
+contains the following attributes:
+
+======================= ==========================================
+power1_bad_fault_log Set to 1 by a power1 bad fault occurring.
+in0_fet_short_fault_log Set to 1 when the ADC detects a FET-short fault.
+in0_fet_bad_fault_log Set to 1 when a FET-BAD fault occurs.
+in1_crit_fault_log Set to 1 by a VDD overvoltage fault occurring.
+in1_lcrit_fault_log Set to 1 by a VDD undervoltage fault occurring.
+curr1_crit_fault_log Set to 1 by an overcurrent fault occurring.
+======================= ==========================================