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android_kernel_samsung_msm8976/Documentation/hwmon/ltc4215

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hwmon: Add LTC4215 driver Add Linux support for the Linear Technology LTC4215 Hot Swap controller I2C monitoring interface. I have tested the driver with my board, and it appears to work fine. With the power supplies disabled, it reads 11.93V input, 1.93V output, no current and no power. With the supplies enabled, it reads 11.93V input, 11.98V output, no current, no power. I'm not drawing any current at the moment, so this is reasonable. The value in the sense register never reads anything except 0, so I expect to get zero from the current and power calculations. I didn't attempt to support changing any of the chip's settings or enabling the FET. I'm not sure even how to do that and still fit within the hwmon framework. :) Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu> Cc: Jean Delvare <khali@linux-fr.org> Cc: "Mark M. Hoffman" <mhoffman@lightlink.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-03-31 22:24:29 +00:00
Kernel driver ltc4215
=====================
Supported chips:
* Linear Technology LTC4215
Prefix: 'ltc4215'
Addresses scanned: 0x44
Datasheet:
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697
Author: Ira W. Snyder <iws@ovro.caltech.edu>
Description
-----------
The LTC4215 controller allows a board to be safely inserted and removed
from a live backplane.
Usage Notes
-----------
This driver does not probe for LTC4215 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 LTC4215 driver Add Linux support for the Linear Technology LTC4215 Hot Swap controller I2C monitoring interface. I have tested the driver with my board, and it appears to work fine. With the power supplies disabled, it reads 11.93V input, 1.93V output, no current and no power. With the supplies enabled, it reads 11.93V input, 11.98V output, no current, no power. I'm not drawing any current at the moment, so this is reasonable. The value in the sense register never reads anything except 0, so I expect to get zero from the current and power calculations. I didn't attempt to support changing any of the chip's settings or enabling the FET. I'm not sure even how to do that and still fit within the hwmon framework. :) Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu> Cc: Jean Delvare <khali@linux-fr.org> Cc: "Mark M. Hoffman" <mhoffman@lightlink.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-03-31 22:24:29 +00:00
Example: the following will load the driver for an LTC4215 at address 0x44
on I2C bus #0:
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 ltc4215
$ echo ltc4215 0x44 > /sys/bus/i2c/devices/i2c-0/new_device
hwmon: Add LTC4215 driver Add Linux support for the Linear Technology LTC4215 Hot Swap controller I2C monitoring interface. I have tested the driver with my board, and it appears to work fine. With the power supplies disabled, it reads 11.93V input, 1.93V output, no current and no power. With the supplies enabled, it reads 11.93V input, 11.98V output, no current, no power. I'm not drawing any current at the moment, so this is reasonable. The value in the sense register never reads anything except 0, so I expect to get zero from the current and power calculations. I didn't attempt to support changing any of the chip's settings or enabling the FET. I'm not sure even how to do that and still fit within the hwmon framework. :) Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu> Cc: Jean Delvare <khali@linux-fr.org> Cc: "Mark M. Hoffman" <mhoffman@lightlink.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-03-31 22:24:29 +00:00
Sysfs entries
-------------
The LTC4215 has built-in limits for overvoltage, undervoltage, and
undercurrent warnings. This makes it very likely that the reference
circuit will be used.
in1_input input voltage
in2_input output voltage
in1_min_alarm input undervoltage alarm
in1_max_alarm input overvoltage alarm
curr1_input current
curr1_max_alarm overcurrent alarm
power1_input power usage
power1_alarm power bad alarm
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