Changes between Version 2 and Version 3 of dma_driver

Timestamp:

Oct 8, 2014, 5:57:50 PM (10 years ago)

Author:

alain

Comment:

--

dma_driver

@@ -19 +19 @@
 The SEG_DMA_BASE virtual address and PERI_CLUSTER_INCREMENT values must be defined in the hard_config.h file.
 
-The addressable registers map is defined [source:soft/giet_vm/giet_drivers/dma_driver.h here].
+The addressable registers map, and the status possible values are defined [source:soft/giet_vm/giet_drivers/dma_driver.h here].
+
+
+==   Low level access functions  ==
+
+ === unsigned int '''_dma_init'''( unsigned int cluster_xy,  unsigned int channel_id ) ===
+This function disables interrupts for one DMA channel in one cluster.As the GIET-VM uses a polling policy to detect DMA transfer completion,
+the DMA component initialisation must disable interrupts.
+Returns 0 if success, returns > 0 if error.
+
+ === unsigned int '''_dma_reset'''( unsigned int  cluster_xy,  unsigned int  channel_id ) ===
+This function re-initialises one DMA channel in one cluster after transfer completion. It actually forces the channel to return in IDLE state.
+
+ === unsigned int '''_dma_get_status'''( unsigned int  cluster_xy,   unsigned int  channel_id );
+This function returns the status of a DMA channel in a given cluster.
+
+ === void '''_dma_start_transfer'''( unsigned int       cluster_xy,  unsigned int channel_id,  unsigned long long dst_paddr,  unsigned long long src_paddr,   unsigned int size ) ===
+This function sets the physical address (including 64 bits extension) of the source and destination buffers for a DMA channel in a given cluster, and sets the transfer size to lauch the transfer.
+
+==  High level access functions ==
+
+ === void '''_dma_copy'''( unsigned int cluster_xy,  unsigned int channel_id,  unsigned int dst_vaddr,  unsigned int src_vaddr,    unsigned int size ) ===
+This function copies a source memory buffer to a destination memory buffer, using virtual addresses. This requires a virtual to physical address translation.
+This blocking function is supposed to be used by the kernel only, and uses a polling policy on DMA_STATUS register to detect completion.
+Therefore, the DMA_IRQ is NOT used.
+The source and destination buffers base addresses must be word aligned, and the buffer's size must be multiple of 4.
+In case of error (buffer unmapped, unaligned, or DMA_STATUS error), an error message is displayed on TTY0, and system crash.
+
+ === void '''_dma_physical_copy'''( unsigned int cluster_xy,  unsigned int channel_id,  unsigned long long dst_paddr,  unsigned long long src_paddr,   unsigned int size ) ===
+This function copies a source memory buffer to a destination memory buffer, using physical addresses.
+This blocking function is supposed to be used by the kernel only, and uses a polling policy on DMA_STATUS register to detect completion.
+Therefore, the DMA_IRQ is NOT used.
+The source and destination buffers base addresses must be word aligned, and the buffer's size must be multiple of 4.
+In case of error (buffer unmapped, unaligned, or DMA_STATUS error), an error message is displayed on TTY0, and system crash.
+
+ === void _dma_isr( unsigned int irq_type,  unsigned int irq_id,  unsigned int channel ) ===
+This Interrupt Service Routine should not be used by the GIET_VM, because the DMA is only used by the kernel in the boot phase, with a polling strategy.
+
+