projects / mirror_ubuntu-kernels.git / blame
| Commit | Line | Data |
|---|---|---|
| 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 | ======================= ============================= |