path: root/Documentation/hwmon/ltc4245
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authorFathi Boudra <fathi.boudra@linaro.org>2013-04-28 09:33:08 +0300
committerFathi Boudra <fathi.boudra@linaro.org>2013-04-28 09:33:08 +0300
commit3b4bd47f8f4ed3aaf7c81c9b5d2d37ad79fadf4a (patch)
treeb9996006addfd7ae70a39672b76843b49aebc189 /Documentation/hwmon/ltc4245
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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>
+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.