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linux/Documentation/hwmon/ltc4245

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hwmon: Add LTC4245 driver Add Linux support for the Linear Technology LTC4245 Multiple Supply Hot Swap controller I2C monitoring interface. Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu> Acked-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Jean Delvare <khali@linux-fr.org>
2009-01-07 15:37:32 +00:00
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
ltc4215/ltc4245: Discard obsolete detect methods There is no point in implementing a detect callback for the LTC4215 and LTC4245, as these devices can't be detected. It was there solely to handle "force" module parameters to instantiate devices, but now we have a better sysfs interface that can do the same. So we can get rid of the ugly module parameters and the detect callbacks. This shrinks the binary module sizes by 36% and 46%, respectively. Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Ira W. Snyder <iws@ovro.caltech.edu>
2009-10-04 20:53:42 +00:00
of the possible addresses are unfriendly to probing. You will have to
instantiate the devices explicitly.
hwmon: Add LTC4245 driver Add Linux support for the Linear Technology LTC4245 Multiple Supply Hot Swap controller I2C monitoring interface. Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu> Acked-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Jean Delvare <khali@linux-fr.org>
2009-01-07 15:37:32 +00:00
Example: the following will load the driver for an LTC4245 at address 0x23
on I2C bus #1:
ltc4215/ltc4245: Discard obsolete detect methods There is no point in implementing a detect callback for the LTC4215 and LTC4245, as these devices can't be detected. It was there solely to handle "force" module parameters to instantiate devices, but now we have a better sysfs interface that can do the same. So we can get rid of the ugly module parameters and the detect callbacks. This shrinks the binary module sizes by 36% and 46%, respectively. Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Ira W. Snyder <iws@ovro.caltech.edu>
2009-10-04 20:53:42 +00:00
$ modprobe ltc4245
$ echo ltc4245 0x23 > /sys/bus/i2c/devices/i2c-1/new_device
hwmon: Add LTC4245 driver Add Linux support for the Linear Technology LTC4245 Multiple Supply Hot Swap controller I2C monitoring interface. Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu> Acked-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Jean Delvare <khali@linux-fr.org>
2009-01-07 15:37:32 +00:00
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
hwmon: (ltc4245) Expose all GPIO pins as analog voltages Add support for exposing all GPIO pins as analog voltages. Though this is not an ideal use of the chip, some hardware engineers may decide that the LTC4245 meets their design requirements when studying the datasheet. The GPIO pins are sampled in round-robin fashion, meaning that a slow reader will see stale data. A userspace application can detect this, because it will get -EAGAIN when reading from a sysfs file which contains stale data. Users can choose to use this feature on a per-chip basis by using either platform data or the OF device tree (where applicable). Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu> Signed-off-by: Jean Delvare <khali@linux-fr.org>
2010-08-14 19:08:49 +00:00
in9_input GPIO voltage data (see note 1)
in10_input GPIO voltage data (see note 1)
in11_input GPIO voltage data (see note 1)
hwmon: Add LTC4245 driver Add Linux support for the Linear Technology LTC4245 Multiple Supply Hot Swap controller I2C monitoring interface. Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu> Acked-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Jean Delvare <khali@linux-fr.org>
2009-01-07 15:37:32 +00:00
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)
hwmon: (ltc4245) Expose all GPIO pins as analog voltages Add support for exposing all GPIO pins as analog voltages. Though this is not an ideal use of the chip, some hardware engineers may decide that the LTC4245 meets their design requirements when studying the datasheet. The GPIO pins are sampled in round-robin fashion, meaning that a slow reader will see stale data. A userspace application can detect this, because it will get -EAGAIN when reading from a sysfs file which contains stale data. Users can choose to use this feature on a per-chip basis by using either platform data or the OF device tree (where applicable). Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu> Signed-off-by: Jean Delvare <khali@linux-fr.org>
2010-08-14 19:08:49 +00:00
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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