= GIET-VM / CMA Driver =

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

It supports the SOLIB ''vci_chbuf_dma'' component, that is a multi channels, chained buffer DMA controller.
This component can be used in conjonction with the SOCLIB ''vci_frame_buffer'' to display images, or with the SOCLIB ''vci_multi_nic controller'' to transfer both RX and TX packets between NIC and memory buffers.

The SEG_CMA_BASE address must be defined in the hard_config.h file

All accesses to CMA registers are done by the two _cma_set_register() and _cma_get_register() low-level functions, that are handling the extended physical addresses.
The higher level access functions are defined in the [wiki:fbf_driver fbf_driver] and [wiki:nic_driver nic_driver] files.

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

 === unsigned int '''_cma_get_register'''( unsigned int channel,  unsigned int index ) ===
This low_level function returns the value contained in register (index).

 === void '''_cma_set_register'''( unsigned int channel,  unsigned int index,  unsigned int value ) ===
This low_level function returns the value contained in register (index).

 === void '''_cma_isr'''( unsigned int irq_type,  unsigned int irq_id,  unsigned int channel ) ===
This Interrupt Service Routine handles the IRQ generated by a CMA channel.