Kernel driver pmbus

Supported chips:

Author: Guenter Roeck <linux@roeck-us.net>

Description

This driver supports hardware monitoring for various PMBus compliant devices. It supports voltage, current, power, and temperature sensors as supported by the device.

Each monitored channel has its own high and low limits, plus a critical limit.

Fan support will be added in a later version of this driver.

Usage Notes

This driver does not probe for PMBus devices, since there is no register which can be safely used to identify the chip (The MFG_ID register is not supported by all chips), and since there is no well defined address range for PMBus devices. You will have to instantiate the devices explicitly.

Example: the following will load the driver for an LTC2978 at address 0x60 on I2C bus #1:

$ modprobe pmbus
$ echo ltc2978 0x60 > /sys/bus/i2c/devices/i2c-1/new_device

Platform data support

Support for additional PMBus chips can be added by defining chip parameters in a new chip specific driver file. For example, (untested) code to add support for Emerson DS1200 power modules might look as follows:

static struct pmbus_driver_info ds1200_info = {
      .pages = 1,
      /* Note: All other sensors are in linear mode */
      .direct[PSC_VOLTAGE_OUT] = true,
      .direct[PSC_TEMPERATURE] = true,
      .direct[PSC_CURRENT_OUT] = true,
      .m[PSC_VOLTAGE_IN] = 1,
      .b[PSC_VOLTAGE_IN] = 0,
      .R[PSC_VOLTAGE_IN] = 3,
      .m[PSC_VOLTAGE_OUT] = 1,
      .b[PSC_VOLTAGE_OUT] = 0,
      .R[PSC_VOLTAGE_OUT] = 3,
      .m[PSC_TEMPERATURE] = 1,
      .b[PSC_TEMPERATURE] = 0,
      .R[PSC_TEMPERATURE] = 3,
      .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN | PMBUS_HAVE_STATUS_INPUT
                 | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
                 | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
                 | PMBUS_HAVE_PIN | PMBUS_HAVE_POUT
                 | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP
                 | PMBUS_HAVE_FAN12 | PMBUS_HAVE_STATUS_FAN12,
};

static int ds1200_probe(struct i2c_client *client)
{
      return pmbus_do_probe(client, &ds1200_info);
}

static const struct i2c_device_id ds1200_id[] = {
      {"ds1200"},
      {}
};

MODULE_DEVICE_TABLE(i2c, ds1200_id);

/* This is the driver that will be inserted */
static struct i2c_driver ds1200_driver = {
      .driver = {
                 .name = "ds1200",
                 },
      .probe = ds1200_probe,
      .id_table = ds1200_id,
};

static int __init ds1200_init(void)
{
      return i2c_add_driver(&ds1200_driver);
}

static void __exit ds1200_exit(void)
{
      i2c_del_driver(&ds1200_driver);
}

Sysfs entries

When probing the chip, the driver identifies which PMBus registers are supported, and determines available sensors from this information. Attribute files only exist if respective sensors are supported by the chip. Labels are provided to inform the user about the sensor associated with a given sysfs entry.

The following attributes are supported. Limits are read-write; all other attributes are read-only.

inX_input

Measured voltage. From READ_VIN or READ_VOUT register.

inX_min

Minimum Voltage. From VIN_UV_WARN_LIMIT or VOUT_UV_WARN_LIMIT register.

inX_max

Maximum voltage. From VIN_OV_WARN_LIMIT or VOUT_OV_WARN_LIMIT register.

inX_lcrit

Critical minimum Voltage. From VIN_UV_FAULT_LIMIT or VOUT_UV_FAULT_LIMIT register.

inX_crit

Critical maximum voltage. From VIN_OV_FAULT_LIMIT or VOUT_OV_FAULT_LIMIT register.

inX_min_alarm

Voltage low alarm. From VOLTAGE_UV_WARNING status.

inX_max_alarm

Voltage high alarm. From VOLTAGE_OV_WARNING status.

inX_lcrit_alarm

Voltage critical low alarm. From VOLTAGE_UV_FAULT status.

inX_crit_alarm

Voltage critical high alarm. From VOLTAGE_OV_FAULT status.

inX_label

“vin”, “vcap”, or “voutY”

inX_rated_min

Minimum rated voltage. From MFR_VIN_MIN or MFR_VOUT_MIN register.

inX_rated_max

Maximum rated voltage. From MFR_VIN_MAX or MFR_VOUT_MAX register.

currX_input

Measured current. From READ_IIN or READ_IOUT register.

currX_max

Maximum current. From IIN_OC_WARN_LIMIT or IOUT_OC_WARN_LIMIT register.

currX_lcrit

Critical minimum output current. From IOUT_UC_FAULT_LIMIT register.

currX_crit

Critical maximum current. From IIN_OC_FAULT_LIMIT or IOUT_OC_FAULT_LIMIT register.

currX_alarm

Current high alarm. From IIN_OC_WARNING or IOUT_OC_WARNING status.

currX_max_alarm

Current high alarm. From IIN_OC_WARN_LIMIT or IOUT_OC_WARN_LIMIT status.

currX_lcrit_alarm

Output current critical low alarm. From IOUT_UC_FAULT status.

currX_crit_alarm

Current critical high alarm. From IIN_OC_FAULT or IOUT_OC_FAULT status.

currX_label

“iin”, “iinY”, “iinY.Z”, “ioutY”, or “ioutY.Z”, where Y reflects the page number and Z reflects the phase.

currX_rated_max

Maximum rated current. From MFR_IIN_MAX or MFR_IOUT_MAX register.

powerX_input

Measured power. From READ_PIN or READ_POUT register.

powerX_cap

Output power cap. From POUT_MAX register.

powerX_max

Power limit. From PIN_OP_WARN_LIMIT or POUT_OP_WARN_LIMIT register.

powerX_crit

Critical output power limit. From POUT_OP_FAULT_LIMIT register.

powerX_alarm

Power high alarm. From PIN_OP_WARNING or POUT_OP_WARNING status.

powerX_crit_alarm

Output power critical high alarm. From POUT_OP_FAULT status.

powerX_label

“pin”, “pinY”, “pinY.Z”, “poutY”, or “poutY.Z”, where Y reflects the page number and Z reflects the phase.

powerX_rated_max

Maximum rated power. From MFR_PIN_MAX or MFR_POUT_MAX register.

tempX_input

Measured temperature. From READ_TEMPERATURE_X register.

tempX_min

Minimum temperature. From UT_WARN_LIMIT register.

tempX_max

Maximum temperature. From OT_WARN_LIMIT register.

tempX_lcrit

Critical low temperature. From UT_FAULT_LIMIT register.

tempX_crit

Critical high temperature. From OT_FAULT_LIMIT register.

tempX_min_alarm

Chip temperature low alarm. Set by comparing READ_TEMPERATURE_X with UT_WARN_LIMIT if TEMP_UT_WARNING status is set.

tempX_max_alarm

Chip temperature high alarm. Set by comparing READ_TEMPERATURE_X with OT_WARN_LIMIT if TEMP_OT_WARNING status is set.

tempX_lcrit_alarm

Chip temperature critical low alarm. Set by comparing READ_TEMPERATURE_X with UT_FAULT_LIMIT if TEMP_UT_FAULT status is set.

tempX_crit_alarm

Chip temperature critical high alarm. Set by comparing READ_TEMPERATURE_X with OT_FAULT_LIMIT if TEMP_OT_FAULT status is set.

tempX_rated_min

Minimum rated temperature. From MFR_TAMBIENT_MIN register.

tempX_rated_max

Maximum rated temperature. From MFR_TAMBIENT_MAX, MFR_MAX_TEMP_1, MFR_MAX_TEMP_2 or MFR_MAX_TEMP_3 register.