a question about DMA ON I.MX31 CSPI

huangdexiang · ‎07-09-2012

We are developing a system based on i.mx31, and the software is based on linux 2.6.28 release by freescale.
In our system, the cspi port is configured as a slave port, 32bit mode. As the released source code does not
support CSPI DMA., we re-write a linux driver to make it work. The driver do work ,but we get the big-endian
data.That is ,in the master data 0x44332211 was sent,but we get 0x11223344 in our dma callback. I don't know
whether if the i.mx31 can solve the byte-order.

Some codes are listed below. The driver is a char driver. Every time we open the device, the function "mxcspi_initdma" is called.

In our system the master port is work on 16MHz CLOCKs, 8 BIT MODE.

We have tried the "SWAP" bit in the TESTREG, but it doesn't work.

#define RXDMA_BUF_NUM   10
#define RXDMA_BUF_SIZE 32*1024 //(600 *1024)//(5120)
#define TXDMA_BUF_SIZE 32*1024

static void mxcspi_dmaread_callback(void *arg, int error, unsigned int cnt)
{
    mxc_dma_requestbuf_t *readchnl_reqelem;
    mxc_cspi_dmamap_t rx_buf_elem;
    volatile unsigned int status;
    int buff_id, num_bufs, i;
    int len;
    int ret;
#ifdef DEBUG_SPI_DRIVER
    int usedspace, freespace;
#endif

    cspi_driver_data_t *drv_data = (cspi_driver_data_t *)arg;

    if (error != MXC_DMA_DONE)
        printk("dma read error\n");

    num_bufs = drv_data->num_rxdma_bufs;
    buff_id = drv_data->dma_rxbuf_id;
    readchnl_reqelem = drv_data->readchnl_reqelem;

    if ((++drv_data->dma_rxbuf_id ) % (num_bufs) == 0){
        drv_data->dma_rxbuf_id = 0;
    }

    rx_buf_elem = (mxc_cspi_dmamap_t *) (drv_data->rx_dmamap + buff_id);

    status = __raw_readl(drv_data->regs + MXC_CSPISTAT);
    if (status & MXC_CSPISTAT_RO){
        printk("in dma read callback:rx fifo overflow\n");
    }
/*
    printk("dma read:0x%x,0x%x,0x%x,0x%x,0x%x,0x%x,0x%x,0x%x\n", \
                rx_buf_elem->buf[0], rx_buf_elem->buf[1], rx_buf_elem->buf[2], rx_buf_elem->buf[3],
                  rx_buf_elem->buf[4], rx_buf_elem->buf[5], rx_buf_elem->buf[6], rx_buf_elem->buf[7]);
*/
#ifdef DEBUG_SPI_DRIVER
        usedspace = kfifo_len(drv_data->readbuffer);
        freespace = max_bufsiz - usedspace;
        if (freespace <= cnt){
            printk("kfifo free space is not enough(free:%d,required:%d)\n", freespace, cnt);
        }
#endif

#if 1
//   i = kfifo_put(drv_data->readbuffer, (unsigned char *)rx_buf_elem->buf, cnt);
#else
    int loop = 0;
    u32 tmp_data;
   // printk("dma cnt:%d,cur buf:%d, rxbuf_id:%d\n", cnt, buff_id, drv_data->dma_rxbuf_id);
    for (loop = 0; loop < cnt/4; loop++) {
        tmp_data = (((rx_buf_elem->buf[loop] >> 24) & 0x000000FFL)
                | ((rx_buf_elem->buf[loop] >> 8) & 0x0000FF00L)
                | ((rx_buf_elem->buf[loop] << 8) & 0x00FF0000L)
                | ((rx_buf_elem->buf[loop] << 24) & 0xFF000000L));
        kfifo_put(drv_data->readbuffer, (char *)&tmp_data, 4);
    }

#endif
    if (kfifo_len(drv_data->readbuffer) >= drv_data->rx_cnt){
        len = kfifo_len(drv_data->readbuffer);
        wake_up_interruptible(&drv_data->rx_buf_wq);
    }

      /* Setup the DMA read request structures */
      rx_buf_elem.src_addr = drv_data->mapbase;
      rx_buf_elem.dst_addr = rx_buf_elem->dma_handle;
      rx_buf_elem.num_of_bytes = = RXDMA_BUF_SIZE;
      ret = mxc_dma_config(drv_data->rx_dma_channel, &readchnl_reqelem, 1 ,
                  MXC_DMA_MODE_READ);
      if (ret != 0) {
          printk("in dma read callback,error config dma\n");
          return ;
      }

      ret = mxc_dma_callback_set(drv_data->rx_dma_channel, mxcspi_dmaread_callback,
                      drv_data);
      if (ret != 0) {
          printk("in dma read callback,error set dma callback\n");
          return;
      }
      ret = mxc_dma_enable(drv_data->rx_dma_channel);
      if (ret != 0){
          printk("Can not enable dma channel:%d\n", drv_data->rx_dma_channel);
          return;
      }

}

static int mxcspi_initdma(cspi_driver_data_t *drv_data)
{
    int status = 0, rxbufs, i;
    struct device *dev;
    mxc_dma_requestbuf_t *readchnl_reqelem;
    mxc_cspi_dmamap_t *rx_buf_elem;

    if (drv_data == NULL){
        printk("drv_data is NULL\n");
        return -1;
    }

    dev = &drv_data->pdev->dev;

    drv_data->dma_rxbuf_id = 0;

    drv_data->rx_dma_channel = mxc_dma_request(drv_data->dma_rx_id, "MXC CSPI Read");
    if (drv_data->rx_dma_channel < 0) {
        dev_err(dev, "Can not get CSPI DMA Read channel\n");
        status = -ENODEV;
        goto err_no_rxchan;
    }

    drv_data->tx_dma_channel = mxc_dma_request(drv_data->dma_tx_id, "MXC CSPI Write");
    if (drv_data->tx_dma_channel < 0) {
        dev_err(dev, "Can not get CSPI DMA Write channel\n");
        status = -ENODEV;
        goto err_no_txchan;
    }

    /* Setup the DMA read request structures */
    readchnl_reqelem = drv_data->readchnl_reqelem;
    rxbufs = drv_data->num_rxdma_bufs;
    for (i = 0; i < rxbufs; i++) {
        rx_buf_elem = (mxc_cspi_dmamap_t *) (drv_data->rx_dmamap + i);
        (readchnl_reqelem + i)->src_addr = drv_data->mapbase;
        (readchnl_reqelem + i)->dst_addr = rx_buf_elem->dma_handle;
        (readchnl_reqelem + i)->num_of_bytes = RXDMA_BUF_SIZE;
    }
    status = mxc_dma_config(drv_data->rx_dma_channel, readchnl_reqelem, rxbufs,
                MXC_DMA_MODE_READ);
    if (status !=0 ){
        dev_err(dev, "Can not config channel:%d\n", drv_data->rx_dma_channel);
        goto err_config_dma;
    }

    status = mxc_dma_callback_set(drv_data->rx_dma_channel, mxcspi_dmaread_callback,
                    drv_data);
    if (status != 0) {
        dev_err(dev, "Can not set dma Callback\n");
        goto err_set_dma_callback;
    }
    status = mxc_dma_enable(drv_data->rx_dma_channel);
    if (status != 0){
        dev_err(dev, "Can not enable dma channel:%d\n", drv_data->rx_dma_channel);
        goto err_en_dma;
    }
    //NOTE!!!!!!!!!!!!
//    tasklet_init(&drv_data->dma_rx_tasklet, dma_rx_do_tasklet, (unsigned long)drv_data);

    drv_data->dma_txchnl_inuse = 0;
    return status;

err_en_dma:
err_set_dma_callback:
err_config_dma:
    mxc_dma_free(drv_data->tx_dma_channel);
    drv_data->tx_dma_channel = -1;
err_no_txchan:
    mxc_dma_free(drv_data->rx_dma_channel);
    drv_data->rx_dma_channel = -1;
err_no_rxchan:
    return status;
}

static int mxcspi_freedma(cspi_driver_data_t *drv_data)
{
    mxc_dma_free(drv_data->tx_dma_channel);
    mxc_dma_free(drv_data->rx_dma_channel);
    drv_data->tx_dma_channel = -1;
    drv_data->rx_dma_channel = -1;
    return 0;
}

static int dma_mem_init(cspi_driver_data_t *drv_data)
{
    int status = 0;
    int rxbufs = 0;
    int i,j;
    struct device *dev;
    mxc_cspi_dmamap_t *rx_buf_elem;

    if (drv_data == NULL){
        printk("drv_data is NULL\n");
        return -1;
    }

    dev = &drv_data->pdev->dev;

    drv_data->tx_buf = kmalloc(TXDMA_BUF_SIZE, GFP_KERNEL);
    if (drv_data->tx_buf == NULL) {
        dev_err(dev, "Can not allocate tx_buf\n");
        status = -ENOMEM;
        goto err_no_txbuff;
    }

    rxbufs = drv_data->num_rxdma_bufs = RXDMA_BUF_NUM;

    drv_data->rx_dmamap = kmalloc(rxbufs * sizeof(mxc_cspi_dmamap_t), GFP_KERNEL);
    if (drv_data->rx_dmamap == NULL) {
        dev_err(dev, "Can not allocate rx_dmamap\n");
        status = -ENOMEM;
        goto err_no_rxbuff;
    }

    /* Allocate the DMA Receive Request structures */
    drv_data->readchnl_reqelem = kmalloc(rxbufs * sizeof(mxc_dma_requestbuf_t), GFP_KERNEL);
    if (drv_data->readchnl_reqelem == NULL) {
        dev_err(dev, "Can not allocate readchnl_reqelem\n");
        status = -ENOMEM;
        goto err_no_dmareq;
    }

    for (i = 0; i< rxbufs; i++) {
        rx_buf_elem = (mxc_cspi_dmamap_t *)(drv_data->rx_dmamap + i);
        rx_buf_elem->buf =
            dma_alloc_coherent(NULL, PAGE_ALIGN(RXDMA_BUF_SIZE),
                       &rx_buf_elem->dma_handle, GFP_DMA);
        if (rx_buf_elem->buf == NULL) {
            dev_err(dev, "Can not allocate rx_buf_elem->buf\n");
            for (j = 0; j< i; j++){
                rx_buf_elem =
                    (mxc_cspi_dmamap_t *)(drv_data->rx_dmamap + j);
                dma_free_coherent(NULL, RXDMA_BUF_SIZE,
                            rx_buf_elem->buf,
                            rx_buf_elem->dma_handle);
            }
            status = -ENOMEM;
            goto err_no_dmamem;
        }
    }

    return status;

err_no_dmamem:
    kfree(drv_data->readchnl_reqelem);
    drv_data->readchnl_reqelem = NULL;
err_no_dmareq:
    kfree(drv_data->rx_dmamap);
    drv_data->rx_dmamap = NULL;

err_no_rxbuff:
    kfree(drv_data->tx_buf);
    drv_data->tx_buf = NULL;
err_no_txbuff:
    return status;
}

static int dma_mem_free(cspi_driver_data_t *drv_data)
{
    int i, rxbufs;
    mxc_cspi_dmamap_t *rx_buf_elem;

    if (drv_data == NULL){
        printk("drv_data is NULL\n");
        return -1;
    }

    rxbufs = drv_data->num_rxdma_bufs;

    if (drv_data->rx_dmamap != NULL){
        for (i = 0; i < rxbufs; i++) {
            rx_buf_elem = (mxc_cspi_dmamap_t *) (drv_data->rx_dmamap + i);
            dma_free_coherent(NULL, RXDMA_BUF_SIZE,
                      rx_buf_elem->buf, rx_buf_elem->dma_handle);
        }
    }
    kfree(drv_data->readchnl_reqelem);
    drv_data->readchnl_reqelem = NULL;

    kfree(drv_data->rx_dmamap);
    drv_data->rx_dmamap = NULL;

    kfree(drv_data->tx_buf);
    drv_data->tx_buf = NULL;

    return 0;
   }

Codes below are added to the arch/arm/mach-mx3/dma.c

static mxc_sdma_channel_params_t mxc_sdma_cspi1_rx_params = {
   .chnl_params = {
           .watermark_level = 32,
           .per_address = CSPI1_BASE_ADDR,
           .peripheral_type = CSPI,
           .transfer_type = per_2_emi,
           .event_id = DMA_REQ_CSPI1_RX,
           .bd_number = 32,
           .word_size = TRANSFER_32BIT,
           },
   .channel_num = MXC_DMA_CHANNEL_CSPI1RX,
   .chnl_priority = MXC_SDMA_DEFAULT_PRIORITY,
};

static mxc_sdma_channel_params_t mxc_sdma_cspi1_tx_params = {
   .chnl_params = {
           .watermark_level = 32,
           .per_address = CSPI1_BASE_ADDR + 0x4,
           .peripheral_type = CSPI,
           .transfer_type = emi_2_per,
           .event_id = DMA_REQ_CSPI1_TX,
           .bd_number = 32,
           .word_size = TRANSFER_32BIT,
           },
   .channel_num = MXC_DMA_CHANNEL_CSPI1_TX,
   .chnl_priority = MXC_SDMA_DEFAULT_PRIORITY,
};

{MXC_DMA_CSPI1_RX, &mxc_sdma_cspi1_rx_params},
{MXC_DMA_CSPI1_TX, &mxc_sdma_cspi1_tx_params},