PIC device API

A) General principles

The PIC generic device describes an external interrupt Controler, that translates N input IRQs generated by external peripherals to N WTI IRQs, that will be routed to a dynamically allocated WTI mailbox in a given cluster.

The max number of input IRQs is defined by the CONFIG_IRQ_PIC_MAX parameter. The actual number of connected IRQs is defined in the arch_info file, and stored in the PIC device extension.

The "source" device for each input IRQ is also defined in the arch_info file, and are stored in the devices_irq global variable in the kernel initialization phase.

This external peripheral does not execute I/O operations, but is just acting as a dynamically configurable interrupt router for another I/O operation. Therefore, ALMOS-MK does not use the PIC device waiting queue, but call directly the PIC driver blocking functions to dynamically configure the PIC component.

B) Access Functions

1) void dev_pic_init( xptr_t xp_dev , uint32_t irq_nr )

This function makes two initializations: It initializes the PIC specific fields of the device descriptor. It call the PIC driver to initialize the PIC hardware device. It is executed once in the kernel initialisation phase.

2) void dev_pic_bind_irq( uint32_t irq_id , cxy_t cxy , uint32_t wti_id )

This function link a WTI mailbox to the PIC input IRQ identified by its index, and unmask the selected input IRQ. The <irq_id> argument is the input IRQ index. The <cxy> argument is the WTI mailbox cluster. The <wti_id> argument is the WTI mailbox index in cluster.

3) void dev_pic_unbind_irq( uint32_t irq_id )

This function mask a PIC input IRQ identified by its index. The <irq_id> argument is the input IRQ index.