linux-imx

/*

 *  linux/drivers/char/ttyprintk.c

 *

 *  Copyright (C) 2010  Samo Pogacnik

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the smems of the GNU General Public License as published by

 * the Free Software Foundation; version 2 of the License.

 */

​

/*

 * This pseudo device allows user to make printk messages. It is possible

 * to store "console" messages inline with kernel messages for better analyses

 * of the boot process, for example.

 */

​

#include <linux/device.h>

#include <linux/serial.h>

#include <linux/tty.h>

#include <linux/module.h>

​

struct ttyprintk_port {

    struct tty_port port;

    struct mutex port_write_mutex;

};

​

static struct ttyprintk_port tpk_port;

​

/*

 * Our simple preformatting supports transparent output of (time-stamped)

 * printk messages (also suitable for logging service):

 * - any cr is replaced by nl

 * - adds a ttyprintk source tag in front of each line

 * - too long message is fragmented, with '\'nl between fragments

 * - TPK_STR_SIZE isn't really the write_room limiting factor, because

 *   it is emptied on the fly during preformatting.

 */

#define TPK_STR_SIZE 508 /* should be bigger then max expected line length */

#define TPK_MAX_ROOM 4096 /* we could assume 4K for instance */

#define TPK_PREFIX KERN_SOH __stringify(CONFIG_TTY_PRINTK_LEVEL)

​

static int tpk_curr;

​

static char tpk_buffer[TPK_STR_SIZE + 4];

​

static void tpk_flush(void)

{

    if (tpk_curr > 0) {

        tpk_buffer[tpk_curr] = '\0';

        printk(TPK_PREFIX "[U] %s\n", tpk_buffer);

        tpk_curr = 0;

    }

}

​

static int tpk_printk(const unsigned char *buf, int count)

{

    int i = tpk_curr;

​

    if (buf == NULL) {

        tpk_flush();

        return i;

    }

​