uart串口驱动

发布时间：2023-03-01 18:00

/dev/ttymxcX=UART1作为终端

两个重要结构体：uart_driver和uart_port 的

每个串口驱动都需要定义一个 uart_driver，

struct uart_driver {
   struct module       *owner;
   const char       *driver_name;
   const char       *dev_name;
   int           major;
   int           minor;
   int           nr;
   struct console       *cons;

   /*
   * these are private; the low level driver should not
   * touch these; they should be initialised to NULL
   */
   struct uart_state   *state;
   struct tty_driver   *tty_driver;
};

加载驱动向系统注册这个 uart_driver:int uart_register_driver(struct uart_driver *drv)

注销驱动的时候也需要注销掉前面注册的 uart_driver：void uart_unregister_driver(struct uart_driver *drv)

——————————————————————————

uart_port(描述具体的串口端口串口外设在内核中的具体的表现)

struct uart_port {
   spinlock_t       lock;           /* port lock */
   unsigned long       iobase;           /* in/out[bwl] */
   unsigned char __iomem   *membase;       /* read/write[bwl] */
   unsigned int       (*serial_in)(struct uart_port *, int);
   void           (*serial_out)(struct uart_port *, int, int);
   void           (*set_termios)(struct uart_port *,
               struct ktermios *new,
               struct ktermios *old);
   void           (*set_mctrl)(struct uart_port *, unsigned int);
   int           (*startup)(struct uart_port *port);
   void           (*shutdown)(struct uart_port *port);
   void           (*throttle)(struct uart_port *port);
   void           (*unthrottle)(struct uart_port *port);
   int           (*handle_irq)(struct uart_port *);
   void           (*pm)(struct uart_port *, unsigned int state,
               unsigned int old);
   void           (*handle_break)(struct uart_port *);
   int           (*rs485_config)(struct uart_port *,
                       struct serial_rs485 *rs485);···

const struct uart_ops *ops;//包含了对串口操作的函数需要我们实现

。。。。。。。。

}

向内核添加一个uart端口

int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)

卸载

int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)

——————————————————————————————

从设备树开始

$\"uart串口驱动_第1张图片\"$

根据属性找到匹配的驱动文件（可以看出串口驱动是和TTY联系在一起的）

$\"uart串口驱动_第2张图片\"$

static struct platform_driver serial_imx_driver = {
.probe = serial_imx_probe,//匹配成功后probe函数要执行此为原版的驱动文件
.remove = serial_imx_remove,

   .suspend   = serial_imx_suspend,
   .resume       = serial_imx_resume,
   .id_table   = imx_uart_devtype,
   .driver       = {
       .name   = \"imx-uart\",
       .of_match_table = imx_uart_dt_ids,
   },
};

//模仿原版的驱动文件

为什么IMX6ULL的串口为dev/ttymxc0,1

int ret = uart_register_driver(&imx_reg);

->static struct uart_driver imx_reg = {
   .owner = THIS_MODULE,
   .driver_name = DRIVER_NAME,#define DRIVER_NAME \"IMX-uart\"
   .dev_name = DEV_NAME,
   .major = SERIAL_IMX_MAJOR,207
   .minor = MINOR_START,16
   .nr = ARRAY_SIZE(imx_ports),
   .cons = IMX_CONSOLE,
};

->#define DEV_NAME \"ttymxc\"

uart_unregister_driver(&imx_reg);

_______________________________________

学习模仿probe函数

//struct imx_port {NXP自定义的
struct uart_port port;。。。。。。。。。}

static int serial_imx_probe(struct platform_device *pdev)
{
   struct imx_port *sport;
   void __iomem *base;
   int ret = 0;
   struct resource *res;
   int txirq, rxirq, rtsirq;

sport = devm_kzalloc//给imx_port 申请内存

serial_imx_probe_dt//处理设备树

platform_get_resource//获取内存

devm_ioremap_resource//得到外设基地址（可以得到所有寄存器地址）

-》uart_port 处理

   sport->port.dev = &pdev->dev;
   sport->port.mapbase = res->start;
   sport->port.membase = base;
   sport->port.type = PORT_IMX,
   sport->port.iotype = UPIO_MEM;
   sport->port.irq = rxirq;
   sport->port.fifosize = 32;
   sport->port.ops = &imx_pops;

ret = devm_request_irq(&pdev->dev, txirq, imx_txint, 0,
dev_name(&pdev->dev), sport);

devm_request_irq---串口接收中断，中断处理函数中获得串口接收到的数据，然后使用tty_flip_buffer_push将其放到tty里面

】

static struct uart_ops imx_pops = {
   .tx_empty   = imx_tx_empty,//与寄存器相关
   .set_mctrl   = imx_set_mctrl,
   .get_mctrl   = imx_get_mctrl,
   .stop_tx   = imx_stop_tx,
   .start_tx   = imx_start_tx,
   .stop_rx   = imx_stop_rx,
   .enable_ms   = imx_enable_ms,
   .break_ctl   = imx_break_ctl,
   .startup   = imx_startup,
   .shutdown   = imx_shutdown,
   .flush_buffer   = imx_flush_buffer,
   .set_termios   = imx_set_termios,
   .type       = imx_type,
   .config_port   = imx_config_port,
   .verify_port   = imx_verify_port,
#if defined(CONFIG_CONSOLE_POLL)
   .poll_init = imx_poll_init,
   .poll_get_char = imx_poll_get_char,
   .poll_put_char = imx_poll_put_char,
#endif
};

uart串口驱动

相关推荐