MTK SPI控制器驱动分析

一.SPI控制器驱动程序

Spi.c (kernel-3.18\drivers\spi\mediatek\mt6735)

   

static const struct of_device_id mt_spi_of_match[] = {

/*{.compatible = "mediatek,SPI1",},*/

{.compatible = "mediatek,mt6735-spi",},

{.compatible = "mediatek,mt6735m-spi",},

{.compatible = "mediatek,mt6753-spi",},

{.compatible = "mediatek,mt6797-spi",},

{},

};

 

MODULE_DEVICE_TABLE(of, mt_spi_of_match);

 

struct platform_driver mt_spi_driver = {

.driver = {

  .name = "mt-spi",

  .owner = THIS_MODULE,

  .of_match_table = mt_spi_of_match,

  },

.probe = mt_spi_probe,

.suspend = mt_spi_suspend,

.resume = mt_spi_resume,

.remove = __exit_p(mt_spi_remove),

};

    

 

mt_spi_init

    ret = platform_driver_register(&mt_spi_driver); //通过匹配DTS里面的{.compatible = "mediatek,mt6735-spi",},进入probe

 

 

mt_spi_probe

    master = spi_alloc_master(&pdev->dev, sizeof(struct mt_spi_t)); //分配mt_spi_t内存,allocate SPI master controller

    regs = platform_get_resource(pdev, IORESOURCE_MEM, 0); //得到IO资源

    irq = platform_get_irq(pdev, 0); //得到平台的中断

    request_mem_region(regs->start, resource_size(regs), pdev->name) //申请内存

    ms->clk_main = devm_clk_get(&pdev->dev, "spi-main"); //得到SPI的clk

    master->mode_bits = (SPI_CPOL | SPI_CPHA); //给spi控制器属性赋值

    master->bus_num = pdev->id;

    master->setup = mt_spi_setup;

    master->transfer = mt_spi_transfer;

    master->cleanup = mt_spi_cleanup;

    ret = request_irq(irq, mt_spi_interrupt, IRQF_TRIGGER_LOW, dev_name(&pdev->dev), ms);//注册SPI控制器中断函数，单独分析1

    enable_clk(ms); //使能时钟

    reset_spi(ms); //重启SPI

    ret = spi_register_master(master); //注册SPI控制器，单独分析2

 

 

 

 

注册SPI控制器中断函数，单独分析1

mt_spi_interrupt

    xfer = ms->cur_transfer;

    msg = list_entry(ms->queue.next, struct spi_message, queue); //从队列获取spi_message

    /*Clear interrupt status first by reading the register */

    reg_val = spi_readl(ms, SPI_STATUS0_REG);

    if (is_fifo_read(msg) && xfer->rx_buf)  //如果是FIFO，读取数据

        reg_val = spi_readl(ms, SPI_RX_DATA_REG);/*get the data from rx */ 

    if (is_last_xfer(msg, xfer))  //如果是最后的spi_message数据 ,就停止读取

mt_spi_msg_done(ms, msg, 0); 

            list_del(&msg->queue); //删除队列

            spi_disable_dma(ms); //关闭DMA

            msg->complete(msg->context); //调用spi_message的complete函数

    else  //如果不是最后的spi_message数据

ms->cur_transfer = ms->next_transfer;

mt_spi_next_xfer(ms, msg); //读取下一个spi_message

            ms->next_transfer = list_entry(xfer->transfer_list.next, struct spi_transfer, transfer_list); //读取spi_transfer

            spi_disable_dma(ms);

            ret = spi_setup_packet(ms);

            /*Using DMA to send data */

    if ((mode == DMA_TRANSFER) || (mode == OTHER1) || (mode == OTHER2)) 

spi_enable_dma(ms, mode); //使能DMA

   

            

 

//注册SPI控制器，单独分析2

spi_register_master(master);

    status = device_add(&master->dev); //加入设备

    list_add_tail(&master->list, &spi_master_list); //加入spi_master_list链表

    list_for_each_entry(bi, &board_list, list) //spi_device的信息的集合,找到用这个设备控制器的设备

spi_match_master_to_boardinfo(master, &bi->board_info);

            if (master->bus_num != bi->bus_num) //如果有spi设备，就进入下一步

            dev = spi_new_device(master, bi); //new 一个spi设备,单独分析3

 

 

new 一个spi设备,单独分析3

spi_new_device

    proxy = spi_alloc_device(master); //分配一个SPI设备

        spi = kzalloc(sizeof(*spi), GFP_KERNEL); 

        spi->master = master;

spi->dev.parent = &master->dev;

spi->dev.bus = &spi_bus_type;

spi->dev.release = spidev_release;

spi->cs_gpio = -ENOENT;

device_initialize(&spi->dev);

    proxy->chip_select = chip->chip_select; //设置这个设备的一些属性，由spi_device里面得到

    proxy->max_speed_hz = chip->max_speed_hz;

    proxy->mode = chip->mode;

    proxy->irq = chip->irq;

    status = spi_add_device(proxy); //加入设备

        status = spi_setup(spi); //setup SPI mode and clock rate

        /* Device may be bound to an active driver when this returns */

status = device_add(&spi->dev);