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This driver adds support for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller. Reviewed-by: Ira W. Snyder <iws@ovro.caltech.edu> Reviewed-by: Tom Grennan <tom.grennan@ericsson.com> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
64 lines
2.1 KiB
Plaintext
64 lines
2.1 KiB
Plaintext
Kernel driver ltc4261
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=====================
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Supported chips:
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* Linear Technology LTC4261
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Prefix: 'ltc4261'
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Addresses scanned: -
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Datasheet:
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http://cds.linear.com/docs/Datasheet/42612fb.pdf
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Author: Guenter Roeck <guenter.roeck@ericsson.com>
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Description
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-----------
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The LTC4261/LTC4261-2 negative voltage Hot Swap controllers allow a board
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to be safely inserted and removed from a live backplane.
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Usage Notes
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-----------
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This driver does not probe for LTC4261 devices, since there is no register
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which can be safely used to identify the chip. You will have to instantiate
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the devices explicitly.
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Example: the following will load the driver for an LTC4261 at address 0x10
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on I2C bus #1:
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$ modprobe ltc4261
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$ echo ltc4261 0x10 > /sys/bus/i2c/devices/i2c-1/new_device
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Sysfs entries
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-------------
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Voltage readings provided by this driver are reported as obtained from the ADC
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registers. If a set of voltage divider resistors is installed, calculate the
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real voltage by multiplying the reported value with (R1+R2)/R2, where R1 is the
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value of the divider resistor against the measured voltage and R2 is the value
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of the divider resistor against Ground.
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Current reading provided by this driver is reported as obtained from the ADC
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Current Sense register. The reported value assumes that a 1 mOhm sense resistor
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is installed. If a different sense resistor is installed, calculate the real
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current by dividing the reported value by the sense resistor value in mOhm.
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The chip has two voltage sensors, but only one set of voltage alarm status bits.
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In many many designs, those alarms are associated with the ADIN2 sensor, due to
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the proximity of the ADIN2 pin to the OV pin. ADIN2 is, however, not available
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on all chip variants. To ensure that the alarm condition is reported to the user,
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report it with both voltage sensors.
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in1_input ADIN2 voltage (mV)
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in1_min_alarm ADIN/ADIN2 Undervoltage alarm
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in1_max_alarm ADIN/ADIN2 Overvoltage alarm
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in2_input ADIN voltage (mV)
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in2_min_alarm ADIN/ADIN2 Undervoltage alarm
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in2_max_alarm ADIN/ADIN2 Overvoltage alarm
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curr1_input SENSE current (mA)
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curr1_alarm SENSE overcurrent alarm
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