Merging upstream version 6.9.7.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 133 insertions, 0 deletions

diff --git a/Documentation/hwmon/ltc4282.rst b/Documentation/hwmon/ltc4282.rst
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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.
+=======================  ==========================================