linux dma 物理地址

#include <linux/module.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>

static int dma_setup(struct device *dev) {
    struct dma_chan *chan;
    dma_cookie_t cookie;
    struct scatterlist sg;
    void *buf;
    dma_addr_t dma_addr;

    // 分配内存
    buf = kmalloc(BUF_SIZE, GFP_KERNEL);
    if (!buf)
        return -ENOMEM;

    // 映射内存为DMA地址
    dma_addr = dma_map_single(dev, buf, BUF_SIZE, DMA_FROM_DEVICE);
    if (dma_mapping_error(dev, dma_addr)) {
        kfree(buf);
        return -EFAULT;
    }

    // 获取DMA通道
    chan = dma_request_channel(mask, filter_fn, filter_param);
    if (!chan) {
        dma_unmap_single(dev, dma_addr, BUF_SIZE, DMA_FROM_DEVICE);
        kfree(buf);
        return -EBUSY;
    }

    // 设置scatterlist
    sg_init_one(&sg, buf, BUF_SIZE);

    // 提交DMA传输
    cookie = dmaengine_prep_slave_single(chan, dma_addr, BUF_SIZE, DMA_FROM_DEVICE, DMA_PREP_INTERRUPT);
    if (!cookie) {
        dma_release_channel(chan);
        dma_unmap_single(dev, dma_addr, BUF_SIZE, DMA_FROM_DEVICE);
        kfree(buf);
        return -EFAULT;
    }

    // 启动传输并等待完成
    dmaengine_submit(chan, &sg);
    dma_async_issue_pending(chan);

    // 等待DMA传输完成
    wait_for_completion(&dma_complete);

    // 清理
    dmaengine_terminate_all(chan);
    dma_unmap_single(dev, dma_addr, BUF_SIZE, DMA_FROM_DEVICE);
    kfree(buf);

    return 0;
}

module_init(dma_setup);
module_exit(dma_cleanup);