The Linux kernel is configured to select the console by passing it the console parameter, for example:

  console=ttyLTQ0,115200
  

It can be checked via cat /proc/cmdline

DMA Engine/LTQ HW Memcpy(ltq_hwmcpy.c)/netowrk: CONFIG_NET_DMA – Asynchronous Transfers/Transforms API

amba-pl08x.c: /driver/dma/—example of memcpy and dma-slave two examples

dma_cap_set(DMA_MEMCPY, pl08x->memcpy.cap_mask);
	pl08x->memcpy.dev = &adev->dev;
	pl08x->memcpy.device_alloc_chan_resources = pl08x_alloc_chan_resources;
	pl08x->memcpy.device_free_chan_resources = pl08x_free_chan_resources;
	pl08x->memcpy.device_prep_dma_memcpy = pl08x_prep_dma_memcpy;
	pl08x->memcpy.device_prep_dma_interrupt = pl08x_prep_dma_interrupt;
	pl08x->memcpy.device_tx_status = pl08x_dma_tx_status;
	pl08x->memcpy.device_issue_pending = pl08x_issue_pending;
	pl08x->memcpy.device_control = pl08x_control;

	/* Initialize slave engine */
	dma_cap_set(DMA_SLAVE, pl08x->slave.cap_mask);
	pl08x->slave.dev = &adev->dev;
	pl08x->slave.device_alloc_chan_resources = pl08x_alloc_chan_resources;
	pl08x->slave.device_free_chan_resources = pl08x_free_chan_resources;
	pl08x->slave.device_prep_dma_interrupt = pl08x_prep_dma_interrupt;
	pl08x->slave.device_tx_status = pl08x_dma_tx_status;
	pl08x->slave.device_issue_pending = pl08x_issue_pending;
	pl08x->slave.device_prep_slave_sg = pl08x_prep_slave_sg;
	pl08x->slave.device_control = pl08x_control;

Linux Module Initialization sequence