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Hi EveryOne! This is first time I send a letter to everyone. If I make mistake, please free to correct me. :) I'm trying to write the first driver which is concerned with DMA. I'm reading dmatest.c and have some confused problem. Oh! No! I have many problem..:D MPC8349's DMA controller like ISA controller but with more features? I want to mean that MPC8349E's DMA controller will send -MEMR, -MEMW, -IOR, -IOW ?. So in DMA APIs such as dma_addr_t dma_map_single(struct device *dev, void *cpu_addr, size_t size, enum dma_data_direction direction) *dev will pointer to DMA controller or to peripheral device(FPGA, ISA device)? From dmatest.c , *dev seem to pointer to a channel of DMA controller. The channel is connected to a peripheral device. So calling the API, DMA controller will be able to access memory from cpu_addr, and peripheral device does too? Look struct dma_async_tx_descriptor *(*device_prep_dma_memcpy)(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src, size_t len, unsigned long flags); I want to DMA from device to memory. So how to I can get address of peripheral device ? Regards! |
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