raspberrypi-dma.c File Reference

Raspberry Pi specific DMA definitions. More...

#include <bsp/raspberrypi-dma.h>

Data Structures
struct	rpi_dma_control_block
struct	rpi_dma_lite_control_block
struct	rpi_dma4_control_block

Macros
#define	DMA4_AD_SHIFT(addr)   ( addr >> 5 )
#define	DMA4_AD_UNSHIFT(addr)   ( addr << 5 )
#define	ADDRESS_LOW(addr)   ( (uintptr_t) ( addr ) & 0xFFFFFFFF )
#define	ADDRESS_HIGH(addr)   ( ( (uintptr_t) ( addr ) >> 32 ) & 0xFF )
#define	BUS_ADDR(addr)   ( ( ( addr ) & ~0xC0000000 ) | 0xC0000000 )

Functions
rtems_status_code	rpi_dma_start_transfer (rpi_dma_channel channel)
	Start a previously initialized DMA transfer on channel.
rtems_status_code	rpi_dma_wait (rpi_dma_channel channel)
	Block until the current DMA transfer on channel completes.
rtems_status_code	rpi_dma_mem_to_mem_init (rpi_dma_channel channel, void *source_address, void *destination_address, uint32_t transfer_length)
	Initialize a memcpy-style DMA transfer from source_address to destination_address of transfer_length bytes on channel.

Detailed Description

Raspberry Pi specific DMA definitions.

Function Documentation

rpi_dma_mem_to_mem_init()

rtems_status_code rpi_dma_mem_to_mem_init	(	rpi_dma_channel	channel,
		void *	source_address,
		void *	destination_address,
		uint32_t	transfer_length
	)

Initialize a memcpy-style DMA transfer from source_address to destination_address of transfer_length bytes on channel.

Allocates and prepares the channel-specific control block, performs required cache maintenance (flush control block and source; invalidate destination), issues CS reset/abort, and writes CONBLK_AD (with DMA4 address packing via DMA4_AD_SHIFT). This function does not start the transfer; call rpi_dma_start_transfer() and then rpi_dma_wait().

Parameters

channel	DMA channel to use (0–6 noarmal DMA, 7–10 lite, 11–14 DMA4).
source_address	Source buffer (must be CPU_CACHE_LINE_BYTES aligned).
destination_address	Destination buffer (must be CPU_CACHE_LINE_BYTES aligned).
transfer_length	Number of bytes to copy.

Return values

RTEMS_SUCCESSFUL	on success.
RTEMS_INVALID_NUMBER	if channel is invalid/unsupported or has no base address.
RTEMS_INVALID_ADDRESS	if source_address or destination_address are misaligned.
RTEMS_NO_MEMORY	if control block allocation failed.

rpi_dma_start_transfer()

rtems_status_code rpi_dma_start_transfer

(

rpi_dma_channel

channel

)

Start a previously initialized DMA transfer on channel.

Expects the channel's CONBLK_AD to point to a valid control block. Sets ACTIVE and required priorities.

Parameters

channel

DMA channel to start.

Return values

RTEMS_SUCCESSFUL	on success.
RTEMS_INVALID_NUMBER	if channel is invalid.

rpi_dma_wait()

rtems_status_code rpi_dma_wait

(

rpi_dma_channel

channel

)

Block until the current DMA transfer on channel completes.

Busy-waits for ACTIVE to clear and frees the control block previously programmed into CONBLK_AD (including DMA4 address unshifting). Does not invalidate/flush user buffers beyond setup done by the init helpers.

Parameters

channel

DMA channel to wait on.

Return values

RTEMS_SUCCESSFUL	on success.
RTEMS_INVALID_NUMBER	if channel is invalid.
RTEMS_UNSATISFIED	if the channel reports an error.