projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| e5f5c99a GR |
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 <[email protected]> | |
| 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 |