HAL I/O

The header file cyg/hal/var_io.h provides definitions of all on-chip peripherals, except for some UART definitions which are provided by the PNX83xx support HAL instead. This header file is automatically included by the architectural header cyg/hal/hal_io.h, so typically application code and other packages will just include the latter. The register addresses are all in kseg1 so will be accessed uncached.

Interrupt Handling

The header file cyg/hal/var_intr.h provides ISR vector numbers for all interrupt sources, for example CYGNUM_HAL_ISR_I2C0 and CYGNUM_HAL_ISR_PIO_1. These vector numbers should be used for calls like cyg_interrupt_create. The header file is automatically included by the architectural header cyg/hal/hal_intr.h, and other packages and application code will normally just include the latter.

The interrupt vectors come in three groups. There are three vectors for the timers implemented by the PR1910 core's coprocessor 0. There are 20 vectors for the other on-chip peripherals, managed by the priority interrupt controller. One of these, CYGNUM_HAL_ISR_PIO is reserved for use by the HAL's interrupt decoding code to detect PIO interrupts. Finally there are 16 vectors for interrupts on the PIO pins.

The eCos HAL macros HAL_INTERRUPT_MASK, HAL_INTERRUPT_UNMASK, HAL_INTERRUPT_ACKNOWLEDGE, HAL_INTERRUPT_CONFIGURE and HAL_INTERRUPT_SET_LEVEL are implemented by the processor HAL. The implementations depend on the interrupt vector. HAL_INTERRUPT_ACKNOWLEDGE is only needed for PIO interrupts, otherwise it is a no-op. HAL_INTERRUPT_CONFIGURE is also only relevant for PIO interrupts.

Interrupt priorities should be in the range 1 to 14, and correspond to the int_priority fields in the pic_int_reg registers. 1 is the lowest priority and 14 the highest. Interrupt priorities are ignored for the three timer interrupts. All PIO interrupt sources operate at the same priority, which is the highest priority assigned to any of the PIO vectors.

Interrupt chaining via the common HAL's configuration option CYGIMP_HAL_COMMON_INTERRUPTS_CHAIN is supported for PIO interrupts only. This makes it possible to connect several external peripherals' interrupt lines to a single PIO pin if desired.

Clock Support

The PR1910 core provides three timers, TMR1, TMR2 and TMR3. TMR1 is used for the eCos system clock. TMR2 is used for gprof-based profiling if enabled, otherwise it can be used by the application. TMR3 is normally used only for the watchdog device driver.

Cache Handling

The PNX8310 has an 8K unified cache, which is automatically initialized and enabled by the eCos startup code. The standard macros HAL_UCACHE_INVALIDATE_ALL and HAL_UCACHE_SYNC are supported, and both the DCACHE and ICACHE variants are just mapped on to these. Working ENABLE, DISABLE and IS_ENABLED macros are provided as well but these are not generally useful on a MIPS processor.

Profiling Support

The PNX8310 HAL provides a profiling timer for use with the gprof profiling package. This uses the PR1910 coprocessor 0 timer TMR2, so application code should not manipulate this timer if profiling is enabled. The MIPS architectural HAL implements the mcount function so profiling is fully supported on all PNX8310-based platforms.

Linker Script

During a build the PNX8310 HAL provides a linker script suitable for use with all C and C++ applications. This also allows parts of the application code and data to be placed in the on-chip deeply embedded memory, using ELF linker sections .dem_text for code, .dem_data for statically initialized data, and .dem_bss for uninitialized data. The dem1.c testcase in this package illustrates how to use this functionality.

Other Issues

The HAL_PLATFORM_RESET is implemented via the PNX8310's system reset unit, and involves a full reset of the core and all peripherals. Hence, whenever a soft reset is performed by the application or via a gdb command, the system should start up again in a clean state, and there is no need for the system to reinitialize all the peripherals.

The PNX8310 HAL does not affect the implementation of data types, stack size definitions, bit indexing, idle thread processing, SMP support, system startup, or debug support.

Other Functionality

The PNX8310 processor HAL only implements functionality defined in the eCos HAL specification and does not export any additional functions.