详解linux dma驱动编写

drivers/dma 

config S3C24XX_DMAC 
  bool "Samsung S3C24XX DMA support" 
  depends on ARCH_S3C24XX || COMPILE_TEST 
  select DMA_ENGINE 
  select DMA_VIRTUAL_CHANNELS 
  help 
   Support for the Samsung S3C24XX DMA controller driver. The 
   DMA controller is having multiple DMA channels which can be 
   configured for different peripherals like audio, UART, SPI. 
   The DMA controller can transfer data from memory to peripheral, 
   periphal to memory, periphal to periphal and memory to memory. 

obj-$(CONFIG_S3C24XX_DMAC) += s3c24xx-dma.o 

static struct platform_driver s3c24xx_dma_driver = { 
  .driver   = { 
    .name  = "s3c24xx-dma", 
  }, 
  .id_table  = s3c24xx_dma_driver_ids, 
  .probe   = s3c24xx_dma_probe, 
  .remove   = s3c24xx_dma_remove, 
}; 
 
module_platform_driver(s3c24xx_dma_driver); 

/* Initialize memcpy engine */ 
dma_cap_set(DMA_MEMCPY, s3cdma->memcpy.cap_mask); 
dma_cap_set(DMA_PRIVATE, s3cdma->memcpy.cap_mask); 
s3cdma->memcpy.dev = &pdev->dev; 
s3cdma->memcpy.device_free_chan_resources = 
        s3c24xx_dma_free_chan_resources; 
s3cdma->memcpy.device_prep_dma_memcpy = s3c24xx_dma_prep_memcpy; 
s3cdma->memcpy.device_tx_status = s3c24xx_dma_tx_status; 
s3cdma->memcpy.device_issue_pending = s3c24xx_dma_issue_pending; 
s3cdma->memcpy.device_config = s3c24xx_dma_set_runtime_config; 
s3cdma->memcpy.device_terminate_all = s3c24xx_dma_terminate_all; 
s3cdma->memcpy.device_synchronize = s3c24xx_dma_synchronize; 
 
/* Initialize slave engine for SoC internal dedicated peripherals */ 
dma_cap_set(DMA_SLAVE, s3cdma->slave.cap_mask); 
dma_cap_set(DMA_CYCLIC, s3cdma->slave.cap_mask); 
dma_cap_set(DMA_PRIVATE, s3cdma->slave.cap_mask); 
s3cdma->slave.dev = &pdev->dev; 
s3cdma->slave.device_free_chan_resources = 
        s3c24xx_dma_free_chan_resources; 
s3cdma->slave.device_tx_status = s3c24xx_dma_tx_status; 
s3cdma->slave.device_issue_pending = s3c24xx_dma_issue_pending; 
s3cdma->slave.device_prep_slave_sg = s3c24xx_dma_prep_slave_sg; 
s3cdma->slave.device_prep_dma_cyclic = s3c24xx_dma_prep_dma_cyclic; 
s3cdma->slave.device_config = s3c24xx_dma_set_runtime_config; 
s3cdma->slave.device_terminate_all = s3c24xx_dma_terminate_all; 
s3cdma->slave.device_synchronize = s3c24xx_dma_synchronize; 
s3cdma->slave.filter.map = pdata->slave_map; 
s3cdma->slave.filter.mapcnt = pdata->slavecnt; 
s3cdma->slave.filter.fn = s3c24xx_dma_filter; 

ret = dma_async_device_register(&s3cdma->memcpy); 
if (ret) { 
  dev_warn(&pdev->dev, 
    "%s failed to register memcpy as an async device - %d\n", 
    __func__, ret); 
  goto err_memcpy_reg; 
} 
 
ret = dma_async_device_register(&s3cdma->slave); 
if (ret) { 
  dev_warn(&pdev->dev, 
    "%s failed to register slave as an async device - %d\n", 
    __func__, ret); 
  goto err_slave_reg; 
}