= GIET_VM / PIC Driver =

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The [source:soft/giet_vm/giet_drivers/pic_driver.c pic_driver.c] and [source:soft/giet_vm/giet_drivers/pic_driver.h pic_driver.h] files define the PIC driver.

The ''vci_pic'' component is a multi-channels interrupt controller, available in the SoCLib components library. This component translate an hardware interrupt generated by an external peripheral (HWI) to a write-triggered interrupt (WTI) that will be sent to an internal ''vci_xcu'' in a given cluster. The PIC component is therefore an external, non replicated peripheral.  

The SEG_PIC_BASE value must be defined in the hard_config.h file.

The addressable registers map is defined [source:soft/giet_vm/giet_drivers/pic_driver.h here].

== __Low level access functions__ ==

 === void '''_pic_set_register'''( unsigned int irq_id,   unsigned int index,   unsigned int value ) ===
This function set a new value in register identified by (irq_id / index).
 * '''irq_id''' : input IRQ index.
 * '''index''' : register offset.
 * '''value''' : value to be written.

 === unsigned int '''_pic_get_register'''( unsigned int irq_id,   unsigned int index ) ===
This function returns the value of register identified by (channel / index).
 * '''irq_id''' : input IRQ index.
 * '''index''' : register offset.

== __access functions__ ==

 === void '''_pic_init'''( unsigned int irq_id,  unsigned int vaddr,  unsigned int extend ) ===
This function initializes and activates a given external IRQ in the PIC component. It writes an XCU mailbox physical address in  the IOPIC_ADDRESS and IOPIC_EXTEND registers, and enables the channel.
 * '''irq_id''' : input IRQ index.
 * '''vaddr''' :  address of the destination XCU register
 * '''extend''' :  cluster_xy for the destination XCU

 === void '''_pic_enable'''( unsigned int irq_id ) ===
This function enables a given external IRQ. The associated WTI maibox address is not modified.
 * '''irq_id''' : source PIC HWI channel

 === void '''_pic_disable'''( unsigned int irq_id) ===
This function disables a given given external IRQ. The associated WTI maibox address is not modified.
 * '''irq_id''' : source PIC HWI channel

 === unsigned int '''_pic_get_status'''( unsigned int irq_id ) === 
This function returns the status of a given HWI.
 * '''irq_id''' : source PIC HWI channel