The FSP layer provides common set of on chip and bus peripheral drivers such as but not limited to gpio, i2c, spi, hsp, ast, aodmic for the various auxiliary processors present in the Jetson. This guide pertains to SPE or AON auxiliary processor. The FSP also provides operating system abstraction layer (OSA) to support different type and flavors of the operating systems, here we are only concerned about FreeRTOS. Since FSP houses common set of drivers across multiple of processors, it implements CPU abstraction layer (CPL) which abstracts away CPU primitives such as but not limited to cache management, barriers, memory managements. More details will be followed in later sections.

OSA Layer

The OSA provides the abstraction to underlying Real Time Operating System (RTOS) (FreeRTOS in this case). This helps in porting the firmware drivers/applications into different RTOS with little to no changes at the firmware drivers/application level. The following files that implement the FreeRTOS OSA can be found in the fsp/source/include/osa/freertosv10/osa directory:

• Semaphore
  • follow osa-semaphore.h for API details.
• Mutex
  • follow osa-mutex.h for API details.
• Event Group
  • follow osa-event-group.h for API details.
• Queue
  • follow osa-queue.h for API details.
• Threads and real time scheduling
  • follow osa-task.h for API details.
• Timer
  • follow osa-timer.h for API details.

CPL Layer

The FSP provides an abstraction to CPU configuration via CPL library. This library includes:

• Cache configuration and control for enable/disable/flush/invalidate the caches
  • follow fsp/source/include/cpu/arm/common/cpu/cache.h for API details.
• Register access
  • follow fsp/source/include/cpu/arm/armv7/cortex-r5/reg-access/reg-access.h for API details.
• CPU synchronization barriers
  • follow fsp/source/include/cpu/arm//common/cpu/barriers.h for API details.
• Vector Interrupt Control (VIC) for configuring, enabling and disabling interrupt and its handlers
  • follow fsp/source/include/cpu/arm/common/cpu/arm-vic.h for API details.
• Chip-ID to get SoC version and SKUs
  • follow fsp/source/include/chipid/chip-id.h for API details.

Drivers

This layer implements common set up peripherals and on chip hardware module drivers. The drivers use OSA and CPL layers to implement CPU or OS specific primitives. For brevity this guide will not detail various drivers' APIs as it can be accessed from their respective header files. For example, API details to use GPIO driver are found at fsp/source/include/gpio/tegra-gpio.h. Additionally, some drivers use port layer implemented at fsp/source/soc/<soc number>/port/aon to abstract away processor specific implementation. Each driver or peripheral has associated ID structure implemented at fsp/source/soc/<soc number>/ids/aon which details peripheral instance related information like base address, irq.