1Kernel driver ltc4245
2=====================
3
4Supported chips:
5
6  * Linear Technology LTC4245
7
8    Prefix: 'ltc4245'
9
10    Addresses scanned: 0x20-0x3f
11
12    Datasheet:
13
14	http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
15
16Author: Ira W. Snyder <iws@ovro.caltech.edu>
17
18
19Description
20-----------
21
22The LTC4245 controller allows a board to be safely inserted and removed
23from a live backplane in multiple supply systems such as CompactPCI and
24PCI Express.
25
26
27Usage Notes
28-----------
29
30This driver does not probe for LTC4245 devices, due to the fact that some
31of the possible addresses are unfriendly to probing. You will have to
32instantiate the devices explicitly.
33
34Example: the following will load the driver for an LTC4245 at address 0x23
35on I2C bus #1::
36
37	$ modprobe ltc4245
38	$ echo ltc4245 0x23 > /sys/bus/i2c/devices/i2c-1/new_device
39
40
41Sysfs entries
42-------------
43
44The LTC4245 has built-in limits for over and under current warnings. This
45makes it very likely that the reference circuit will be used.
46
47This driver uses the values in the datasheet to change the register values
48into the values specified in the sysfs-interface document. The current readings
49rely on the sense resistors listed in Table 2: "Sense Resistor Values".
50
51======================= =======================================================
52in1_input		12v input voltage (mV)
53in2_input		5v  input voltage (mV)
54in3_input		3v  input voltage (mV)
55in4_input		Vee (-12v) input voltage (mV)
56
57in1_min_alarm		12v input undervoltage alarm
58in2_min_alarm		5v  input undervoltage alarm
59in3_min_alarm		3v  input undervoltage alarm
60in4_min_alarm		Vee (-12v) input undervoltage alarm
61
62curr1_input		12v current (mA)
63curr2_input		5v  current (mA)
64curr3_input		3v  current (mA)
65curr4_input		Vee (-12v) current (mA)
66
67curr1_max_alarm		12v overcurrent alarm
68curr2_max_alarm		5v  overcurrent alarm
69curr3_max_alarm		3v  overcurrent alarm
70curr4_max_alarm		Vee (-12v) overcurrent alarm
71
72in5_input		12v output voltage (mV)
73in6_input		5v  output voltage (mV)
74in7_input		3v  output voltage (mV)
75in8_input		Vee (-12v) output voltage (mV)
76
77in5_min_alarm		12v output undervoltage alarm
78in6_min_alarm		5v  output undervoltage alarm
79in7_min_alarm		3v  output undervoltage alarm
80in8_min_alarm		Vee (-12v) output undervoltage alarm
81
82in9_input		GPIO voltage data (see note 1)
83in10_input		GPIO voltage data (see note 1)
84in11_input		GPIO voltage data (see note 1)
85
86power1_input		12v power usage (mW)
87power2_input		5v  power usage (mW)
88power3_input		3v  power usage (mW)
89power4_input		Vee (-12v) power usage (mW)
90======================= =======================================================
91
92
93Note 1
94------
95
96If you have NOT configured the driver to sample all GPIO pins as analog
97voltages, then the in10_input and in11_input sysfs attributes will not be
98created. The driver will sample the GPIO pin that is currently connected to the
99ADC as an analog voltage, and report the value in in9_input.
100
101If you have configured the driver to sample all GPIO pins as analog voltages,
102then they will be sampled in round-robin fashion. If userspace reads too
103slowly, -EAGAIN will be returned when you read the sysfs attribute containing
104the sensor reading.
105
106The LTC4245 chip can be configured to sample all GPIO pins with two methods:
107
1081) platform data -- see include/linux/platform_data/ltc4245.h
1092) OF device tree -- add the "ltc4245,use-extra-gpios" property to each chip
110
111The default mode of operation is to sample a single GPIO pin.
112