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-rw-r--r--drivers/char/ttyprintk.c231
1 files changed, 231 insertions, 0 deletions
diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
new file mode 100644
index 0000000000..5af804c17a
--- /dev/null
+++ b/drivers/char/ttyprintk.c
@@ -0,0 +1,231 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/drivers/char/ttyprintk.c
+ *
+ * Copyright (C) 2010 Samo Pogacnik
+ */
+
+/*
+ * 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/console.h>
+#include <linux/device.h>
+#include <linux/serial.h>
+#include <linux/tty.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+
+struct ttyprintk_port {
+ struct tty_port port;
+ spinlock_t spinlock;
+};
+
+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 u8 *buf, int count)
+{
+ int i;
+
+ for (i = 0; i < count; i++) {
+ if (tpk_curr >= TPK_STR_SIZE) {
+ /* end of tmp buffer reached: cut the message in two */
+ tpk_buffer[tpk_curr++] = '\\';
+ tpk_flush();
+ }
+
+ switch (buf[i]) {
+ case '\r':
+ tpk_flush();
+ if ((i + 1) < count && buf[i + 1] == '\n')
+ i++;
+ break;
+ case '\n':
+ tpk_flush();
+ break;
+ default:
+ tpk_buffer[tpk_curr++] = buf[i];
+ break;
+ }
+ }
+
+ 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;
+
+ tty_port_close(&tpkp->port, tty, filp);
+}
+
+/*
+ * TTY operations write function.
+ */
+static ssize_t tpk_write(struct tty_struct *tty, const u8 *buf, size_t count)
+{
+ struct ttyprintk_port *tpkp = tty->driver_data;
+ unsigned long flags;
+ int ret;
+
+ /* exclusive use of tpk_printk within this tty */
+ spin_lock_irqsave(&tpkp->spinlock, flags);
+ ret = tpk_printk(buf, count);
+ spin_unlock_irqrestore(&tpkp->spinlock, flags);
+
+ return ret;
+}
+
+/*
+ * TTY operations write_room function.
+ */
+static unsigned int tpk_write_room(struct tty_struct *tty)
+{
+ return TPK_MAX_ROOM;
+}
+
+/*
+ * TTY operations hangup function.
+ */
+static void tpk_hangup(struct tty_struct *tty)
+{
+ struct ttyprintk_port *tpkp = tty->driver_data;
+
+ tty_port_hangup(&tpkp->port);
+}
+
+/*
+ * TTY port operations shutdown function.
+ */
+static void tpk_port_shutdown(struct tty_port *tport)
+{
+ struct ttyprintk_port *tpkp =
+ container_of(tport, struct ttyprintk_port, port);
+ unsigned long flags;
+
+ spin_lock_irqsave(&tpkp->spinlock, flags);
+ tpk_flush();
+ spin_unlock_irqrestore(&tpkp->spinlock, flags);
+}
+
+static const struct tty_operations ttyprintk_ops = {
+ .open = tpk_open,
+ .close = tpk_close,
+ .write = tpk_write,
+ .write_room = tpk_write_room,
+ .hangup = tpk_hangup,
+};
+
+static const struct tty_port_operations tpk_port_ops = {
+ .shutdown = tpk_port_shutdown,
+};
+
+static struct tty_driver *ttyprintk_driver;
+
+static struct tty_driver *ttyprintk_console_device(struct console *c,
+ int *index)
+{
+ *index = 0;
+ return ttyprintk_driver;
+}
+
+static struct console ttyprintk_console = {
+ .name = "ttyprintk",
+ .device = ttyprintk_console_device,
+};
+
+static int __init ttyprintk_init(void)
+{
+ int ret;
+
+ spin_lock_init(&tpk_port.spinlock);
+
+ 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 = &tpk_port_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;
+ }
+
+ register_console(&ttyprintk_console);
+
+ return 0;
+
+error:
+ tty_driver_kref_put(ttyprintk_driver);
+ tty_port_destroy(&tpk_port.port);
+ return ret;
+}
+
+static void __exit ttyprintk_exit(void)
+{
+ unregister_console(&ttyprintk_console);
+ tty_unregister_driver(ttyprintk_driver);
+ tty_driver_kref_put(ttyprintk_driver);
+ tty_port_destroy(&tpk_port.port);
+}
+
+device_initcall(ttyprintk_init);
+module_exit(ttyprintk_exit);
+
+MODULE_LICENSE("GPL");