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platform-interrupt-controller-API.rst

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Platform Interrupt Controller API documentation

Contents

This document lists the optional platform interrupt controller API that abstracts the runtime configuration and control of interrupt controller from the generic code. The mandatory APIs are described in the porting guide.

1.   Function: unsigned int plat_ic_get_running_priority(void); [optional]

Argument : void
Return   : unsigned int

This API should return the priority of the interrupt the PE is currently servicing. This must be be called only after an interrupt has already been acknowledged via. plat_ic_acknowledge_interrupt.

In the case of Arm standard platforms using GIC, the Running Priority Register is read to determine the priority of the interrupt.

2.   Function: int plat_ic_is_spi(unsigned int id); [optional]

Argument : unsigned int
Return   : int

The API should return whether the interrupt ID (first parameter) is categorized as a Shared Peripheral Interrupt. Shared Peripheral Interrupts are typically associated to system-wide peripherals, and these interrupts can target any PE in the system.

3.   Function: int plat_ic_is_ppi(unsigned int id); [optional]

Argument : unsigned int
Return   : int

The API should return whether the interrupt ID (first parameter) is categorized as a Private Peripheral Interrupt. Private Peripheral Interrupts are typically associated with peripherals that are private to each PE. Interrupts from private peripherals target to that PE only.

4.   Function: int plat_ic_is_sgi(unsigned int id); [optional]

Argument : unsigned int
Return   : int

The API should return whether the interrupt ID (first parameter) is categorized as a Software Generated Interrupt. Software Generated Interrupts are raised by explicit programming by software, and are typically used in inter-PE communication. Secure SGIs are reserved for use by Secure world software.

5.   Function: unsigned int plat_ic_get_interrupt_active(unsigned int id); [optional]

Argument : unsigned int
Return   : int

This API should return the active status of the interrupt ID specified by the first parameter, id.

In case of Arm standard platforms using GIC, the implementation of the API reads the GIC Set Active Register to read and return the active status of the interrupt.

6.   Function: void plat_ic_enable_interrupt(unsigned int id); [optional]

Argument : unsigned int
Return   : void

This API should enable the interrupt ID specified by the first parameter, id. PEs in the system are expected to receive only enabled interrupts.

In case of Arm standard platforms using GIC, the implementation of the API inserts barrier to make memory updates visible before enabling interrupt, and then writes to GIC Set Enable Register to enable the interrupt.

7.   Function: void plat_ic_disable_interrupt(unsigned int id); [optional]

Argument : unsigned int
Return   : void

This API should disable the interrupt ID specified by the first parameter, id. PEs in the system are not expected to receive disabled interrupts.

In case of Arm standard platforms using GIC, the implementation of the API writes to GIC Clear Enable Register to disable the interrupt, and inserts barrier to make memory updates visible afterwards.

8.   Function: void plat_ic_set_interrupt_priority(unsigned int id, unsigned int priority); [optional]

Argument : unsigned int
Argument : unsigned int
Return   : void

This API should set the priority of the interrupt specified by first parameter id to the value set by the second parameter priority.

In case of Arm standard platforms using GIC, the implementation of the API writes to GIC Priority Register set interrupt priority.

9.   Function: int plat_ic_has_interrupt_type(unsigned int type); [optional]

Argument : unsigned int
Return   : int

This API should return whether the platform supports a given interrupt type. The parameter type shall be one of INTR_TYPE_EL3, INTR_TYPE_S_EL1, or INTR_TYPE_NS.

In case of Arm standard platforms using GICv3, the implementation of the API returns 1 for all interrupt types.

In case of Arm standard platforms using GICv2, the API always return 1 for INTR_TYPE_NS. Return value for other types depends on the value of build option GICV2_G0_FOR_EL3:

  • For interrupt type INTR_TYPE_EL3:
    • When GICV2_G0_FOR_EL3 is 0, it returns 0, indicating no support for EL3 interrupts.
    • When GICV2_G0_FOR_EL3 is 1, it returns 1, indicating support for EL3 interrupts.
  • For interrupt type INTR_TYPE_S_EL1:
    • When GICV2_G0_FOR_EL3 is 0, it returns 1, indicating support for Secure EL1 interrupts.
    • When GICV2_G0_FOR_EL3 is 1, it returns 0, indicating no support for Secure EL1 interrupts.

10.   Function: void plat_ic_set_interrupt_type(unsigned int id, unsigned int type); [optional]

Argument : unsigned int
Argument : unsigned int
Return   : void

This API should set the interrupt specified by first parameter id to the type specified by second parameter type. The type parameter can be one of:

  • INTR_TYPE_NS: interrupt is meant to be consumed by the Non-secure world.
  • INTR_TYPE_S_EL1: interrupt is meant to be consumed by Secure EL1.
  • INTR_TYPE_EL3: interrupt is meant to be consumed by EL3.

In case of Arm standard platforms using GIC, the implementation of the API writes to the GIC Group Register and Group Modifier Register (only GICv3) to assign the interrupt to the right group.

For GICv3:

  • INTR_TYPE_NS maps to Group 1 interrupt.
  • INTR_TYPE_S_EL1 maps to Secure Group 1 interrupt.
  • INTR_TYPE_EL3 maps to Secure Group 0 interrupt.

For GICv2:

  • INTR_TYPE_NS maps to Group 1 interrupt.
  • When the build option GICV2_G0_FOR_EL3 is set to 0 (the default), INTR_TYPE_S_EL1 maps to Group 0. Otherwise, INTR_TYPE_EL3 maps to Group 0 interrupt.

11.   Function: void plat_ic_raise_el3_sgi(int sgi_num, u_register_t target); [optional]

Argument : int
Argument : u_register_t
Return   : void

This API should raise an EL3 SGI. The first parameter, sgi_num, specifies the ID of the SGI. The second parameter, target, must be the MPIDR of the target PE.

In case of Arm standard platforms using GIC, the implementation of the API inserts barrier to make memory updates visible before raising SGI, then writes to appropriate SGI Register in order to raise the EL3 SGI.

12.   Function: void plat_ic_set_spi_routing(unsigned int id, unsigned int routing_mode, u_register_t mpidr); [optional]

Argument : unsigned int
Argument : unsigned int
Argument : u_register_t
Return   : void

This API should set the routing mode of Share Peripheral Interrupt (SPI) specified by first parameter id to that specified by the second parameter routing_mode.

The routing_mode parameter can be one of:

  • INTR_ROUTING_MODE_ANY means the interrupt can be routed to any PE in the system. The mpidr parameter is ignored in this case.
  • INTR_ROUTING_MODE_PE means the interrupt is routed to the PE whose MPIDR value is specified by the parameter mpidr.

In case of Arm standard platforms using GIC, the implementation of the API writes to the GIC Target Register (GICv2) or Route Register (GICv3) to set the routing.

13.   Function: void plat_ic_set_interrupt_pending(unsigned int id); [optional]

Argument : unsigned int
Return   : void

This API should set the interrupt specified by first parameter id to Pending.

In case of Arm standard platforms using GIC, the implementation of the API inserts barrier to make memory updates visible before setting interrupt pending, and writes to the GIC Set Pending Register to set the interrupt pending status.

14.   Function: void plat_ic_clear_interrupt_pending(unsigned int id); [optional]

Argument : unsigned int
Return   : void

This API should clear the Pending status of the interrupt specified by first parameter id.

In case of Arm standard platforms using GIC, the implementation of the API writes to the GIC Clear Pending Register to clear the interrupt pending status, and inserts barrier to make memory updates visible afterwards.

15.   Function: unsigned int plat_ic_set_priority_mask(unsigned int id); [optional]

Argument : unsigned int
Return   : int

This API should set the priority mask (first parameter) in the interrupt controller such that only interrupts of higher priority than the supplied one may be signalled to the PE. The API should return the current priority value that it's overwriting.

In case of Arm standard platforms using GIC, the implementation of the API inserts to order memory updates before updating mask, then writes to the GIC Priority Mask Register, and make sure memory updates are visible before potential trigger due to mask update.

16.   Function: unsigned int plat_ic_get_interrupt_id(unsigned int raw); [optional]

Argument : unsigned int
Return   : unsigned int

This API should extract and return the interrupt number from the raw value obtained by the acknowledging the interrupt (read using plat_ic_acknowledge_interrupt()). If the interrupt ID is invalid, this API should return INTR_ID_UNAVAILABLE.

In case of Arm standard platforms using GIC, the implementation of the API masks out the interrupt ID field from the acknowledged value from GIC.

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