1e4b76830SShawn McCarney# rail 2e4b76830SShawn McCarney 3e4b76830SShawn McCarney## Description 4e4b76830SShawn McCarney 5e4b76830SShawn McCarneyA voltage rail that is enabled or monitored by the power sequencer device. 6e4b76830SShawn McCarney 79ec0d43dSShawn McCarneyThe "check_status_vout", "compare_voltage_to_limit", and "gpio" properties 8e4b76830SShawn McCarneyspecify how to obtain the pgood status of the rail. You can specify more than 9*dd6c3661SShawn McCarneyone of these properties. 10*dd6c3661SShawn McCarney 11*dd6c3661SShawn McCarneyThe "check_status_vout" method is usually the most accurate. For example, if a 12*dd6c3661SShawn McCarneypgood fault occurs, the power sequencer device may automatically shut off 13*dd6c3661SShawn McCarneyrelated rails. Ideally the device will only set fault bits in STATUS_VOUT for 14*dd6c3661SShawn McCarneythe rail with the pgood fault. However, all the related rails will likely appear 15*dd6c3661SShawn McCarneyto be faulted by the other methods. 16*dd6c3661SShawn McCarney 17*dd6c3661SShawn McCarneyThe "compare_voltage_to_limit" method is helpful when a rail fails to power on 18*dd6c3661SShawn McCarneyduring the power on sequence and the power sequencer device waits indefinitely 19*dd6c3661SShawn McCarneyfor it to power on. 20*dd6c3661SShawn McCarney 21*dd6c3661SShawn McCarneyThe "gpio" method is necessary when no PMBus information is available for the 22*dd6c3661SShawn McCarneyrail. It is also helpful when a rail fails to power on during the power on 23*dd6c3661SShawn McCarneysequence and the power sequencer device waits indefinitely for it to power on. 24e4b76830SShawn McCarney 25e4b76830SShawn McCarney## Properties 26e4b76830SShawn McCarney 27e4b76830SShawn McCarney| Name | Required | Type | Description | 289ec0d43dSShawn McCarney| :----------------------- | :-----------------: | :---------------------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | 29e4b76830SShawn McCarney| name | yes | string | Unique name for the rail. Can only contain letters (A-Z, a-z), numbers (0-9), period (.), and underscore (\_). | 30e4b76830SShawn McCarney| presence | no | string | D-Bus inventory path of a system component which must be present in order for the rail to be present. If this property is not specified, the rail is assumed to always be present. | 31e4b76830SShawn McCarney| page | see [notes](#notes) | number | PMBus PAGE number of the rail. | 3216e493afSShawn McCarney| is_power_supply_rail | no | boolean (true or false) | If true, this rail is produced by a power supply. Power supply rails require special error handling. If an error is detected in a power supply device, and the pgood status is false for a power supply rail, the power supply error is logged as the cause of the pgood failure. The default value of this property is false. | 33e4b76830SShawn McCarney| check_status_vout | no | boolean (true or false) | If true, determine the pgood status of the rail by checking the value of the PMBus STATUS_VOUT command. If one of the error bits is set, the rail pgood will be considered false. The default value of this property is false. | 349ec0d43dSShawn McCarney| compare_voltage_to_limit | no | boolean (true or false) | If true, determine the pgood status of the rail by comparing the output voltage (READ_VOUT) to the undervoltage fault limit (VOUT_UV_FAULT_LIMIT). If the output voltage is below this limit, the rail pgood will be considered false. The default value of this property is false. | 35e4b76830SShawn McCarney| gpio | no | [gpio](gpio.md) | Determine the pgood status of the rail by reading a GPIO. | 36e4b76830SShawn McCarney 37e4b76830SShawn McCarney### Notes 38e4b76830SShawn McCarney 39e4b76830SShawn McCarney- The "page" property is required if the "check_status_vout" or 409ec0d43dSShawn McCarney "compare_voltage_to_limit" property is true. 41e4b76830SShawn McCarney 42e4b76830SShawn McCarney## Examples 43e4b76830SShawn McCarney 44e4b76830SShawn McCarney``` 45e4b76830SShawn McCarney{ 46e4b76830SShawn McCarney "name": "VDD_CPU0", 47e4b76830SShawn McCarney "page": 11, 48e4b76830SShawn McCarney "check_status_vout": true 49e4b76830SShawn McCarney} 50e4b76830SShawn McCarney``` 51e4b76830SShawn McCarney 52e4b76830SShawn McCarney``` 53e4b76830SShawn McCarney{ 54e4b76830SShawn McCarney "name": "VCS_CPU1", 55e4b76830SShawn McCarney "presence": "/xyz/openbmc_project/inventory/system/chassis/motherboard/cpu1", 56e4b76830SShawn McCarney "gpio": { "line": 60 } 57e4b76830SShawn McCarney} 58e4b76830SShawn McCarney``` 59