从内核空间配置串行端口

Question

如何在内核模块中配置串口。我在初始化模块函数中执行此操作。相同的配置在用户PSACE中工作。我正在使用以下代码来配置串行端口。

mm_segment_t oldfs;
oldfs = get_fs();
set_fs(KERNEL_DS);
fp = filp_open("/dev/ttyS0",O_RDWR | O_NOCTTY | O_NDELAY);
tty = (struct tty_struct *)fp->private_data;
setting the required configuration(tty->termios)
set_fs(oldfs);

Answer 1

串口操作的几乎所有功能都是由drivers/tty/serial/serial_core.c实现的。如果您想以不同的方式执行此操作，请提供您自己的函数以进行uart_ops include/linux/serial_core.h

struct uart_ops {
        unsigned int    (*tx_empty)(struct uart_port *);
        void            (*set_mctrl)(struct uart_port *, unsigned int mctrl);
        unsigned int    (*get_mctrl)(struct uart_port *);
        void            (*stop_tx)(struct uart_port *);
        void            (*start_tx)(struct uart_port *);
        void            (*send_xchar)(struct uart_port *, char ch);
        void            (*stop_rx)(struct uart_port *);
        void            (*enable_ms)(struct uart_port *);
        void            (*break_ctl)(struct uart_port *, int ctl);
        int             (*startup)(struct uart_port *);
        void            (*shutdown)(struct uart_port *);
        void            (*flush_buffer)(struct uart_port *);
        void            (*set_termios)(struct uart_port *, struct ktermios *new,
                                       struct ktermios *old);
        void            (*set_ldisc)(struct uart_port *, int new);
        void            (*pm)(struct uart_port *, unsigned int state,
                              unsigned int oldstate);
        int             (*set_wake)(struct uart_port *, unsigned int state);
        const char *    (*type)(struct uart_port *);
        void            (*release_port)(struct uart_port *);
        int             (*request_port)(struct uart_port *);
        void            (*config_port)(struct uart_port *, int);
        int             (*verify_port)(struct uart_port *, struct serial_struct *);
        int             (*ioctl)(struct uart_port *, unsigned int, unsigned long);
#ifdef CONFIG_CONSOLE_POLL
        void    (*poll_put_char)(struct uart_port *, unsigned char);
        int             (*poll_get_char)(struct uart_port *);
#endif
};

在您的情况下，您需要实现set_termios函数。另外，请查看uart_get_divisor()以了解如何设置波特率。