Initial import

1 files changed, 228 insertions, 0 deletions

diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
new file mode 100644
index 000000000..a15ce4ef3
--- /dev/null
+++ b/drivers/char/ttyprintk.c
@@ -0,0 +1,228 @@
+/*
+ *  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");