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1 | Kernel driver ltc4261 | ||
2 | ===================== | ||
3 | |||
4 | Supported chips: | ||
5 | * Linear Technology LTC4261 | ||
6 | Prefix: 'ltc4261' | ||
7 | Addresses scanned: - | ||
8 | Datasheet: | ||
9 | http://cds.linear.com/docs/Datasheet/42612fb.pdf | ||
10 | |||
11 | Author: Guenter Roeck <guenter.roeck@ericsson.com> | ||
12 | |||
13 | |||
14 | Description | ||
15 | ----------- | ||
16 | |||
17 | The LTC4261/LTC4261-2 negative voltage Hot Swap controllers allow a board | ||
18 | to be safely inserted and removed from a live backplane. | ||
19 | |||
20 | |||
21 | Usage Notes | ||
22 | ----------- | ||
23 | |||
24 | This driver does not probe for LTC4261 devices, since there is no register | ||
25 | which can be safely used to identify the chip. You will have to instantiate | ||
26 | the devices explicitly. | ||
27 | |||
28 | Example: the following will load the driver for an LTC4261 at address 0x10 | ||
29 | on I2C bus #1: | ||
30 | $ modprobe ltc4261 | ||
31 | $ echo ltc4261 0x10 > /sys/bus/i2c/devices/i2c-1/new_device | ||
32 | |||
33 | |||
34 | Sysfs entries | ||
35 | ------------- | ||
36 | |||
37 | Voltage readings provided by this driver are reported as obtained from the ADC | ||
38 | registers. If a set of voltage divider resistors is installed, calculate the | ||
39 | real voltage by multiplying the reported value with (R1+R2)/R2, where R1 is the | ||
40 | value of the divider resistor against the measured voltage and R2 is the value | ||
41 | of the divider resistor against Ground. | ||
42 | |||
43 | Current reading provided by this driver is reported as obtained from the ADC | ||
44 | Current Sense register. The reported value assumes that a 1 mOhm sense resistor | ||
45 | is installed. If a different sense resistor is installed, calculate the real | ||
46 | current by dividing the reported value by the sense resistor value in mOhm. | ||
47 | |||
48 | The chip has two voltage sensors, but only one set of voltage alarm status bits. | ||
49 | In many many designs, those alarms are associated with the ADIN2 sensor, due to | ||
50 | the proximity of the ADIN2 pin to the OV pin. ADIN2 is, however, not available | ||
51 | on all chip variants. To ensure that the alarm condition is reported to the user, | ||
52 | report it with both voltage sensors. | ||
53 | |||
54 | in1_input ADIN2 voltage (mV) | ||
55 | in1_min_alarm ADIN/ADIN2 Undervoltage alarm | ||
56 | in1_max_alarm ADIN/ADIN2 Overvoltage alarm | ||
57 | |||
58 | in2_input ADIN voltage (mV) | ||
59 | in2_min_alarm ADIN/ADIN2 Undervoltage alarm | ||
60 | in2_max_alarm ADIN/ADIN2 Overvoltage alarm | ||
61 | |||
62 | curr1_input SENSE current (mA) | ||
63 | curr1_alarm SENSE overcurrent alarm | ||