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e5f5c99a GR |
1 | Kernel driver ltc4261 |
2 | ===================== | |
3 | ||
4 | Supported chips: | |
b32570a4 | 5 | |
e5f5c99a | 6 | * Linear Technology LTC4261 |
b32570a4 | 7 | |
e5f5c99a | 8 | Prefix: 'ltc4261' |
b32570a4 | 9 | |
e5f5c99a | 10 | Addresses scanned: - |
b32570a4 | 11 | |
e5f5c99a | 12 | Datasheet: |
b32570a4 MCC |
13 | |
14 | http://cds.linear.com/docs/Datasheet/42612fb.pdf | |
e5f5c99a | 15 | |
e3333e57 | 16 | Author: Guenter Roeck <linux@roeck-us.net> |
e5f5c99a GR |
17 | |
18 | ||
19 | Description | |
20 | ----------- | |
21 | ||
22 | The LTC4261/LTC4261-2 negative voltage Hot Swap controllers allow a board | |
23 | to be safely inserted and removed from a live backplane. | |
24 | ||
25 | ||
26 | Usage Notes | |
27 | ----------- | |
28 | ||
29 | This driver does not probe for LTC4261 devices, since there is no register | |
30 | which can be safely used to identify the chip. You will have to instantiate | |
31 | the devices explicitly. | |
32 | ||
33 | Example: the following will load the driver for an LTC4261 at address 0x10 | |
b32570a4 MCC |
34 | on I2C bus #1:: |
35 | ||
36 | $ modprobe ltc4261 | |
37 | $ echo ltc4261 0x10 > /sys/bus/i2c/devices/i2c-1/new_device | |
e5f5c99a GR |
38 | |
39 | ||
40 | Sysfs entries | |
41 | ------------- | |
42 | ||
43 | Voltage readings provided by this driver are reported as obtained from the ADC | |
44 | registers. If a set of voltage divider resistors is installed, calculate the | |
45 | real voltage by multiplying the reported value with (R1+R2)/R2, where R1 is the | |
46 | value of the divider resistor against the measured voltage and R2 is the value | |
47 | of the divider resistor against Ground. | |
48 | ||
49 | Current reading provided by this driver is reported as obtained from the ADC | |
50 | Current Sense register. The reported value assumes that a 1 mOhm sense resistor | |
51 | is installed. If a different sense resistor is installed, calculate the real | |
52 | current by dividing the reported value by the sense resistor value in mOhm. | |
53 | ||
54 | The chip has two voltage sensors, but only one set of voltage alarm status bits. | |
55 | In many many designs, those alarms are associated with the ADIN2 sensor, due to | |
56 | the proximity of the ADIN2 pin to the OV pin. ADIN2 is, however, not available | |
57 | on all chip variants. To ensure that the alarm condition is reported to the user, | |
58 | report it with both voltage sensors. | |
59 | ||
b32570a4 | 60 | ======================= ============================= |
e5f5c99a GR |
61 | in1_input ADIN2 voltage (mV) |
62 | in1_min_alarm ADIN/ADIN2 Undervoltage alarm | |
63 | in1_max_alarm ADIN/ADIN2 Overvoltage alarm | |
64 | ||
65 | in2_input ADIN voltage (mV) | |
66 | in2_min_alarm ADIN/ADIN2 Undervoltage alarm | |
67 | in2_max_alarm ADIN/ADIN2 Overvoltage alarm | |
68 | ||
69 | curr1_input SENSE current (mA) | |
70 | curr1_alarm SENSE overcurrent alarm | |
b32570a4 | 71 | ======================= ============================= |