| .. 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 Sรก <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. |
| ======================= ========================================== |
