函数源码

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source File:arch\x86\boot\early_serial_console.c Create Date:2022-07-27 08:25:53
首页 Copyright©Brick

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static void parse_earlyprintk(void)
{
    int baud = DEFAULT_BAUD;
    char arg[32];
    int pos = 0;
    int port = 0;
 
    if (cmdline_find_option("earlyprintk", arg, sizeof(arg)) > 0) {
        char *e;
 
        if (!strncmp(arg, "serial", 6)) {
            port = DEFAULT_SERIAL_PORT;
            pos += 6;
        }
 
        if (arg[pos] == ',')
            pos++;
 
        /*
         * make sure we have
         *  "serial,0x3f8,115200"
         *  "serial,ttyS0,115200"
         *  "ttyS0,115200"
         */
        if (pos == 7 && !strncmp(arg + pos, "0x", 2)) {
            port = simple_strtoull(arg + pos, &e, 16);
            if (port == 0 || arg + pos == e)
                port = DEFAULT_SERIAL_PORT;
            else
                pos = e - arg;
        } else if (!strncmp(arg + pos, "ttyS", 4)) {
            static const int bases[] = { 0x3f8, 0x2f8 };
            int idx = 0;
 
            /* += strlen("ttyS"); */
            pos += 4;
 
            if (arg[pos++] == '1')
                idx = 1;
 
            port = bases[idx];
        }
 
        if (arg[pos] == ',')
            pos++;
 
        baud = simple_strtoull(arg + pos, &e, 0);
        if (baud == 0 || arg + pos == e)
            baud = DEFAULT_BAUD;
    }
 
    if (port)
        early_serial_init(port, baud);
}