EC Time Alarm Service

The following sections define the operation and definition of the optional control method-based Time and Alarm device, which provides a hardware independent abstraction and a more robust alternative to the Real Time Clock (RTC)

ACPI specification details are in version 6.5 Chapter 9.

9. ACPI-Defined Devices and Device-Specific Objects — ACPI Specification 6.5 documentation (uefi.org)

EC_TAS_GET_GCP

This object is required and provides the OSPM with a bit mask of the device capabilities.

9. ACPI-Defined Devices and Device-Specific Objects — ACPI Specification 6.5 documentation

Input Parameters

Input parameters as described in ACPI specification.

Output Parameters

Should return structure as defined by ACPI specification

FFA ACPI

Method (_GCP) {
  // Check to make sure FFA is available and not unloaded
  If(LEqual(\\_SB.FFA0.AVAL,One)) {
    CreateQwordField(BUFF,0,STAT) // Out – Status for req/rsp
    CreateField(BUFF,128,128,UUID) // UUID of service
    CreateByteField(BUFF,32, CMDD) // In – First byte of command
    CreateDwordField(BUFF,32,GCPD) // Out – 32-bit integer described above
  
    Store(0x1, CMDD) // EC_TAS_GET_GCP
    Store(ToUUID("23ea63ed-b593-46ea-b027-8924df88e92f"), UUID) // RTC
    Store(Store(BUFF, \_SB_.FFA0.FFAC), BUFF)

    If(LEqual(STAT,0x0) ) // Check FF-A successful?
    {
      Return (GCDD)
    }
  }
  Return(Zero)
}

EC_TAS_GET_GRT

This object is required if the capabilities bit 2 is set to 1. The OSPM can use this object to get time. The return value is a buffer containing the time information as described below.

9. ACPI-Defined Devices and Device-Specific Objects — ACPI Specification 6.5 documentation

Input Parameters

Input parameters as described in ACPI specification.

Output Parameters

Should return structure as defined by ACPI specification

FFA ACPI Example

Method (_GRT) {
  // Check to make sure FFA is available and not unloaded
  If(LEqual(\\_SB.FFA0.AVAL,One)) {
    CreateQwordField(BUFF,0,STAT) // Out – Status for req/rsp
    CreateField(BUFF,128,128,UUID) // UUID of service
    CreateByteField(BUFF,32, CMDD) // In – First byte of command
    CreateWordField(BUFF,32,GRT0)  // Out Year
    CreateByteField(BUFF,36,GRT1)  // Out Month
    CreateByteField(BUFF,37,GRT2)  // Out Day
    CreateByteField(BUFF,38,GRT3)  // Out Hour
    CreateByteField(BUFF,39,GRT4)  // Out Minute
    CreateByteField(BUFF,40,GRT5)  // Out Second
    CreateByteField(BUFF,41,GRT6)  // Out Valid
    CreateWordField(BUFF,42,GRT7)  // Out milliseconds
    CreateWordField(BUFF,44,GRT8)  // Out Timezone
    CreateByteField(BUFF,46,GRT9)  // Out Daylight
    CreateField(BUFF,376,24,PAD0)  // Out 3 bytes padding


    Store(0x2, CMDD) // EC_TAS_GET_GRT
    Store(ToUUID("23ea63ed-b593-46ea-b027-8924df88e92f"), UUID) // RTC
    Store(Store(BUFF, \_SB_.FFA0.FFAC), BUFF)

    If(LEqual(STAT,0x0) ) // Check FF-A successful?
    {
      Return (Package() {GRT0,GRT1,GRT2,GRT3,GRT4,GRT5,GRT6,GRT7,GRT8,GRT9, PAD0})
    }
  }
  Return(Package() {0,0,0,0,0,0,0,0,0,0,Buffer(){0,0,0}})
}

EC_TAS_SET_SRT

This object is required if the capabilities bit 2 is set to 1. The OSPM can use this object to set the time.

9. ACPI-Defined Devices and Device-Specific Objects — ACPI Specification 6.5 documentation

Input Parameters

Input parameters as described in ACPI specification.

Output Parameters

Should return structure as defined by ACPI specification

FFA ACPI Example

Method (_SRT) {
  // Check to make sure FFA is available and not unloaded
  If(LEqual(\\_SB.FFA0.AVAL,One)) {
    CreateQwordField(BUFF,0,STAT) // Out – Status for req/rsp
    CreateField(BUFF,128,128,UUID) // UUID of service
    CreateByteField(BUFF,32, CMDD) // In – First byte of command
    CreateField(BUFF,264,128,SRTD)  // 16 bytes of data

    Store(0x3, CMDD) // EC_TAS_SET_SRT
    Store(ToUUID("23ea63ed-b593-46ea-b027-8924df88e92f"), UUID) // RTC
    Store(Arg0, SRTD) // Copy over the RTC data
    Store(Store(BUFF, \_SB_.FFA0.FFAC), BUFF)

    If(LEqual(STAT,0x0) ) // Check FF-A successful?
    {
      Return (One)
    }
  }
  Return(Zero)}
}

EC_TAS_GET_GWS

This object is required if the capabilities bit 0 is set to 1. It enables the OSPM to read the status of wake alarms

9. ACPI-Defined Devices and Device-Specific Objects — ACPI Specification 6.5 documentation

Input Parameters

Input parameters as described in ACPI specification.

Output Parameters

Should return structure as defined by ACPI specification

FFA ACPI Example

Method (_GWS) {
  // Check to make sure FFA is available and not unloaded
  If(LEqual(\\_SB.FFA0.AVAL,One)) {
    CreateQwordField(BUFF,0,STAT) // Out – Status for req/rsp
    CreateField(BUFF,128,128,UUID) // UUID of service
    CreateByteField(BUFF,32, CMDD) // In – First byte of command
    CreateDwordField(BUFF,33,GWS1) // In – Dword for timer type AC/DC
    CreateDwordField(BUFF,32,GWSD) // Out – Dword timer state

    Store(20, LENG)
    Store(0x4, CMDD) // EC_TAS_GET_GWS
    Store(Arg0, GWS1)
    Store(ToUUID("23ea63ed-b593-46ea-b027-8924df88e92f"), UUID) // RTC
    Store(Store(BUFF, \_SB_.FFA0.FFAC), BUFF)

    If(LEqual(STAT,0x0) ) // Check FF-A successful?
    {
      Return (GWSD)
    } 
  } 
  Return(Zero)
}

EC_TAS_SET_CWS

This object is required if the capabilities bit 0 is set to 1. It enables the OSPM to clear the status of wake alarms

9. ACPI-Defined Devices and Device-Specific Objects — ACPI Specification 6.5 documentation

Input Parameters

Input parameters as described in ACPI specification.

Output Parameters

Should return structure as defined by ACPI specification

FFA ACPI Example

Method (_CWS) {
  // Check to make sure FFA is available and not unloaded
  If(LEqual(\\_SB.FFA0.AVAL,One)) {
    CreateQwordField(BUFF,0,STAT) // Out – Status for req/rsp
    CreateField(BUFF,128,128,UUID) // UUID of service
    CreateByteField(BUFF,32, CMDD) // In – First byte of command
    CreateDwordField(BUFF,33, CWS1) // In – Dword for timer type AC/DC
    CreateDwordField(BUFF,32,CWSD) // Out – Dword timer state
 
    Store(20, LENG)
    Store(0x5, CMDD) // EC_TAS_SET_CWS
    Store(Arg0,CWS1)
    Store(ToUUID("23ea63ed-b593-46ea-b027-8924df88e92f"), UUID) // RTC
    Store(Store(BUFF, \_SB_.FFA0.FFAC), BUFF)

    If(LEqual(STAT,0x0) ) // Check FF-A successful?
    {
      Return (CWSD)
    }
  } 
  Return(Zero)
}

EC_TAS_SET_STV

This object is required if the capabilities bit 0 is set to 1. It sets the timer to the specified value. 

9. ACPI-Defined Devices and Device-Specific Objects — ACPI Specification 6.5 documentation

Input Parameters

Input parameters as described in ACPI specification.

Output Parameters

Should return structure as defined by ACPI specification

FFA ACPI Example

Method (_STV) {
  // Check to make sure FFA is available and not unloaded
  If(LEqual(\\_SB.FFA0.AVAL,One)) {
    CreateQwordField(BUFF,0,STAT) // Out – Status for req/rsp
    CreateField(BUFF,128,128,UUID) // UUID of service
    CreateByteField(BUFF,32, CMDD) // In – First byte of command
    CreateDwordField(BUFF,33, STV1) // In – Dword for timer type AC/DC
    CreateDwordField(BUFF,37, STV2) // In – Dword Timer Value
    CreateDwordField(BUFF,2,STVD) // Out – Dword timer state

    Store(0x6, CMDD) // EC_TAS_SET_STV
    Store(Arg0,STV1)
    Store(Arg1,STV2)
    Store(ToUUID("23ea63ed-b593-46ea-b027-8924df88e92f"), UUID) // RTC
    Store(Store(BUFF, \_SB_.FFA0.FFAC), BUFF)
  
    If(LEqual(STAT,0x0) ) // Check FF-A successful?
    {
      Return (STVD)
    }
  }
  Return(Zero)
}

EC_TAS_GET_TIV

This object is required if the capabilities bit 0 is set to 1. It returns the remaining time of the specified timer before that expires.

9. ACPI-Defined Devices and Device-Specific Objects — ACPI Specification 6.5 documentation

Input Parameters

Input parameters as described in ACPI specification.

Output Parameters

Should return structure as defined by ACPI specification

FFA ACPI Example

Method (_TIV) {
  // Check to make sure FFA is available and not unloaded
  If(LEqual(\\_SB.FFA0.AVAL,One)) {
    CreateQwordField(BUFF,0,STAT) // Out – Status for req/rsp
    CreateField(BUFF,128,128,UUID) // UUID of service
    CreateByteField(BUFF,32, CMDD) // In – First byte of command
    CreateDwordField(BUFF,33, TIV1) // In – Dword for timer type AC/DC
    CreateDwordField(BUFF,32,TIVD) // Out – Dword timer state

    Store(0x7, CMDD) // EC_TAS_GET_TIV
    Store(Arg0,TIV1)
    Store(ToUUID("23ea63ed-b593-46ea-b027-8924df88e92f"), UUID) // RTC
    Store(Store(BUFF, \_SB_.FFA0.FFAC), BUFF)

    If(LEqual(STAT,0x0) ) // Check FF-A successful?
    {
      Return (TIVD)
    }
  }
  Return(Zero)
}