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- Kernel driver ltc4245
- =====================
- Supported chips:
- * Linear Technology LTC4245
- Prefix: 'ltc4245'
- Addresses scanned: 0x20-0x3f
- Datasheet:
- http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
- Author: Ira W. Snyder <iws@ovro.caltech.edu>
- Description
- -----------
- The LTC4245 controller allows a board to be safely inserted and removed
- from a live backplane in multiple supply systems such as CompactPCI and
- PCI Express.
- Usage Notes
- -----------
- This driver does not probe for LTC4245 devices, due to the fact that some
- of the possible addresses are unfriendly to probing. You will have to
- instantiate the devices explicitly.
- Example: the following will load the driver for an LTC4245 at address 0x23
- on I2C bus #1:
- $ modprobe ltc4245
- $ echo ltc4245 0x23 > /sys/bus/i2c/devices/i2c-1/new_device
- Sysfs entries
- -------------
- The LTC4245 has built-in limits for over and under current warnings. This
- makes it very likely that the reference circuit will be used.
- This driver uses the values in the datasheet to change the register values
- into the values specified in the sysfs-interface document. The current readings
- rely on the sense resistors listed in Table 2: "Sense Resistor Values".
- in1_input 12v input voltage (mV)
- in2_input 5v input voltage (mV)
- in3_input 3v input voltage (mV)
- in4_input Vee (-12v) input voltage (mV)
- in1_min_alarm 12v input undervoltage alarm
- in2_min_alarm 5v input undervoltage alarm
- in3_min_alarm 3v input undervoltage alarm
- in4_min_alarm Vee (-12v) input undervoltage alarm
- curr1_input 12v current (mA)
- curr2_input 5v current (mA)
- curr3_input 3v current (mA)
- curr4_input Vee (-12v) current (mA)
- curr1_max_alarm 12v overcurrent alarm
- curr2_max_alarm 5v overcurrent alarm
- curr3_max_alarm 3v overcurrent alarm
- curr4_max_alarm Vee (-12v) overcurrent alarm
- in5_input 12v output voltage (mV)
- in6_input 5v output voltage (mV)
- in7_input 3v output voltage (mV)
- in8_input Vee (-12v) output voltage (mV)
- in5_min_alarm 12v output undervoltage alarm
- in6_min_alarm 5v output undervoltage alarm
- in7_min_alarm 3v output undervoltage alarm
- in8_min_alarm Vee (-12v) output undervoltage alarm
- in9_input GPIO voltage data (see note 1)
- in10_input GPIO voltage data (see note 1)
- in11_input GPIO voltage data (see note 1)
- power1_input 12v power usage (mW)
- power2_input 5v power usage (mW)
- power3_input 3v power usage (mW)
- power4_input Vee (-12v) power usage (mW)
- Note 1
- ------
- If you have NOT configured the driver to sample all GPIO pins as analog
- voltages, then the in10_input and in11_input sysfs attributes will not be
- created. The driver will sample the GPIO pin that is currently connected to the
- ADC as an analog voltage, and report the value in in9_input.
- If you have configured the driver to sample all GPIO pins as analog voltages,
- then they will be sampled in round-robin fashion. If userspace reads too
- slowly, -EAGAIN will be returned when you read the sysfs attribute containing
- the sensor reading.
- The LTC4245 chip can be configured to sample all GPIO pins with two methods:
- 1) platform data -- see include/linux/i2c/ltc4245.h
- 2) OF device tree -- add the "ltc4245,use-extra-gpios" property to each chip
- The default mode of operation is to sample a single GPIO pin.
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