The mobile computing market incorporates end-devices across smartphones, laptops, wearables, and eXtended Reality (XR). The advanced range of Arm Cortex-A processors power these devices, with the Arm A-profile architecture as the underlying foundation to each processor. This page provides an overview of Arm system architecture specifications in the mobile computing market, focusing on three key areas: system architecture for System on Chip (SoC) design, software standards, and security.
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System architecture for SoC design | Software standards | Security

System architecture for SoC design

Successful SoC implementation requires attention to many aspects of integration and system architecture. Arm offers SoC standardization and system architecture in key areas including interconnect standards, security implementation, and power control integration.

Trusted Base System Architecture for Armv8-A

Trusted Base System Architecture (TBSA) for the A-profile architecture provides trusted SoC infrastructure requirements and implementation guidance, compliant with key industry standards and specifications.

The TBSA-A specification covers:

  • TrustZone technology
  • TBSA system architecture
  • Security implementation requirements
  • Lifecycle management
  • Debug, peripheral, and memory considerations
  • Requirements checklist

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Power Control System Architecture

Power Control System Architecture (PCSA) provides power control system architecture for SoCs, based on Arm components.

This specification is useful to architects and designers of SoCs based on Arm components, and component designers incorporating Arm low-power interfaces for clock and power control.

The PCSA specification covers:

  • Voltage, power, and clock partitioning and dependencies
  • Power states and modes
  • Arm power control framework and integration principles
  • Arm component-specific power and clock integration
  • Designing IP with Arm low-power Q-Channel and P-Channel interfaces

The PCSA specification (DEN0050) is under development and can be accessed through an NDA by contacting Arm and quoting the document number: DEN0050.

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Advanced Microcontroller Bus Architecture

Advanced Microcontroller Bus Architecture (AMBA) is an open standard for the connection and management of functional blocks in an SoC.

AMBA protocols and interfaces are used extensively in mobile computing. AMBA provides a common standard to connect various components, enabling design reuse and a low friction SoC integration. SoC designers also have access to a comprehensive marketplace of third-party IP products, tools and services, reducing risk, cost of ownership, and time-to-market.

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Software standards

The use of software standards and their adoption by operating systems and standard firmware vendors provides common interfaces. This eases integration and reduces the per-implementation cost of ownership.

Secure Monitor Call Calling Convention

The Secure Monitor Call Calling Convention (SMCCC) specification defines a common calling mechanism to be used with the Secure Monitor Call (SMC) and Hypervisor Call (HVC) instructions, in both the Armv7 and Armv8 architectures.

The SMCCC specification aims to ease integration and reduce fragmentation between software layers, including: 

  • Operating Systems (OS)
  • Hypervisors
  • Trusted OSs
  • Secure Monitors
  • System Firmware

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Power State Coordination Interface (PSCI)

Power State Coordination Interface (PSCI) is a standard interface for power management that OS vendors can use for supervisory software, working at different levels of privilege on Arm. The aim of this standard is to ease the integration of supervisory software from different vendors.

The PSCI specification defines an interface for:

  • Core idle management
  • Dynamic addition and removal of cores, and secondary core boot
  • System shutdown and reset

PSCI layers onto SCMI and works alongside hardware discovery technologies, for example Flattened Device Tree (FDT), and Advanced Configuration and Power Interface (ACPI).

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System Control and Management Interface

System Control and Management Interface (SCMI) is a standard interface between an OS and a System Control Processor (SCP). SCMI is extensible and provides protocols to access functions which are often implemented in firmware.

The SCMI specification currently provides protocols for:

  • Discovery of supported interfaces
  • Power domain management
  • Performance management
  • Clock management
  • Sensor management
  • Reset management

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Arm software standards

Access all Arm software standards for use in mobile computing, including the SCMI specifications through the software standards page:



Building on Arm TrustZone technology, our security documentation - part of the Platform Security Architecture (PSA) program - provides the foundations for trusted execution environments.

Download our security documentation below:

Trusted Boot and Firmware Update

The Trusted Boot and Firmware Update (TBFU) Specification provides the system and firmware technical requirements for firmware boot and update.

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Firmware Framework for A-profile architecture

The Firmware Framework for A (FF-A) specification provides a standard programming environment and fundamental Root of Trust (RoT) for secure applications on an A-profile product.

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Trusted Firmware-A

Trusted Firmware-A (TF-A) is an open-source reference implementation of Secure world software for Arm A-profile architectures.

TF-A implements Arm interface standards, including:

  • Power State Coordination Interface (PSCI)
  • Trusted Board Boot Requirements for Client (TBBR-CLIENT)
  • SMC Calling Convention (SMCCC)
  • System Control and Management Interface (SCMI)
  • Software Delegated Exception Interface (SDEI)

The code is portable and reusable across hardware platforms and software models that are based on the Armv8-A and Armv7-A architectures.

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