--- /dev/null
+/*
+ * 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 fragmeted, with '\'nl between fragments
+ * - TPK_STR_SIZE isn't really the write_room limiting factor, bcause
+ * 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 */
+static const char *tpk_tag = "[U] "; /* U for User */
+static int tpk_curr;
+
+static int tpk_printk(const unsigned char *buf, int count)
+{
+ static char tmp[TPK_STR_SIZE + 4];
+ int i = tpk_curr;
+
+ if (buf == NULL) {
+ /* flush tmp[] */
+ if (tpk_curr > 0) {
+ /* non nl or cr terminated message - add nl */
+ tmp[tpk_curr + 0] = '\n';
+ tmp[tpk_curr + 1] = '\0';
+ printk(KERN_INFO "%s%s", tpk_tag, tmp);
+ tpk_curr = 0;
+ }
+ return i;
+ }
+
+ for (i = 0; i < count; i++) {
+ tmp[tpk_curr] = buf[i];
+ if (tpk_curr < TPK_STR_SIZE) {
+ switch (buf[i]) {
+ case '\r':
+ /* replace cr with nl */
+ tmp[tpk_curr + 0] = '\n';
+ tmp[tpk_curr + 1] = '\0';
+ printk(KERN_INFO "%s%s", tpk_tag, tmp);
+ tpk_curr = 0;
+ if ((i + 1) < count && buf[i + 1] == '\n')
+ i++;
+ break;
+ case '\n':
+ tmp[tpk_curr + 1] = '\0';
+ printk(KERN_INFO "%s%s", tpk_tag, tmp);
+ tpk_curr = 0;
+ break;
+ default:
+ tpk_curr++;
+ }
+ } else {
+ /* end of tmp buffer reached: cut the message in two */
+ tmp[tpk_curr + 1] = '\\';
+ tmp[tpk_curr + 2] = '\n';
+ tmp[tpk_curr + 3] = '\0';
+ printk(KERN_INFO "%s%s", tpk_tag, tmp);
+ tpk_curr = 0;
+ }
+ }
+
+ return count;
+}
+
+/*
+ * TTY operations open function.
+ */
+static int tpk_open(struct tty_struct *tty, struct file *filp)
+{
+ tty->driver_data = &tpk_port;
+
+ return tty_port_open(&tpk_port.port, tty, filp);
+}
+
+/*
+ * TTY operations close function.
+ */
+static void tpk_close(struct tty_struct *tty, struct file *filp)
+{
+ struct ttyprintk_port *tpkp = tty->driver_data;
+
+ mutex_lock(&tpkp->port_write_mutex);
+ /* flush tpk_printk buffer */
+ tpk_printk(NULL, 0);
+ mutex_unlock(&tpkp->port_write_mutex);
+
+ tty_port_close(&tpkp->port, tty, filp);
+}
+
+/*
+ * TTY operations write function.
+ */
+static int tpk_write(struct tty_struct *tty,
+ const unsigned char *buf, int count)
+{
+ struct ttyprintk_port *tpkp = tty->driver_data;
+ int ret;
+
+
+ /* exclusive use of tpk_printk within this tty */
+ mutex_lock(&tpkp->port_write_mutex);
+ ret = tpk_printk(buf, count);
+ mutex_unlock(&tpkp->port_write_mutex);
+
+ return ret;
+}
+
+/*
+ * TTY operations write_room function.
+ */
+static int tpk_write_room(struct tty_struct *tty)
+{
+ return TPK_MAX_ROOM;
+}
+
+/*
+ * TTY operations ioctl function.
+ */
+static int tpk_ioctl(struct tty_struct *tty,
+ unsigned int cmd, unsigned long arg)
+{
+ struct ttyprintk_port *tpkp = tty->driver_data;
+
+ if (!tpkp)
+ return -EINVAL;
+
+ switch (cmd) {
+ /* Stop TIOCCONS */
+ case TIOCCONS:
+ return -EOPNOTSUPP;
+ default:
+ return -ENOIOCTLCMD;
+ }
+ return 0;
+}
+
+static const struct tty_operations ttyprintk_ops = {
+ .open = tpk_open,
+ .close = tpk_close,
+ .write = tpk_write,
+ .write_room = tpk_write_room,
+ .ioctl = tpk_ioctl,
+};
+
+static struct tty_port_operations null_ops = { };
+
+static struct tty_driver *ttyprintk_driver;
+
+static int __init ttyprintk_init(void)
+{
+ int ret = -ENOMEM;
+
+ mutex_init(&tpk_port.port_write_mutex);
+
+ ttyprintk_driver = tty_alloc_driver(1,
+ TTY_DRIVER_RESET_TERMIOS |
+ TTY_DRIVER_REAL_RAW |
+ TTY_DRIVER_UNNUMBERED_NODE);
+ if (IS_ERR(ttyprintk_driver))
+ return PTR_ERR(ttyprintk_driver);
+
+ tty_port_init(&tpk_port.port);
+ tpk_port.port.ops = &null_ops;
+
+ ttyprintk_driver->driver_name = "ttyprintk";
+ ttyprintk_driver->name = "ttyprintk";
+ ttyprintk_driver->major = TTYAUX_MAJOR;
+ ttyprintk_driver->minor_start = 3;
+ ttyprintk_driver->type = TTY_DRIVER_TYPE_CONSOLE;
+ ttyprintk_driver->init_termios = tty_std_termios;
+ ttyprintk_driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET;
+ tty_set_operations(ttyprintk_driver, &ttyprintk_ops);
+ tty_port_link_device(&tpk_port.port, ttyprintk_driver, 0);
+
+ ret = tty_register_driver(ttyprintk_driver);
+ if (ret < 0) {
+ printk(KERN_ERR "Couldn't register ttyprintk driver\n");
+ goto error;
+ }
+
+ return 0;
+
+error:
+ put_tty_driver(ttyprintk_driver);
+ tty_port_destroy(&tpk_port.port);
+ return ret;
+}
+
+static void __exit ttyprintk_exit(void)
+{
+ tty_unregister_driver(ttyprintk_driver);
+ put_tty_driver(ttyprintk_driver);
+ tty_port_destroy(&tpk_port.port);
+}
+
+device_initcall(ttyprintk_init);
+module_exit(ttyprintk_exit);
+
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff