1 files changed, 343 insertions, 0 deletions
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
new file mode 100644
index 000000000..6e81d782d
--- /dev/null
+++ b/drivers/tty/serial/kgdboc.c
@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Based on the same principle as kgdboe using the NETPOLL api, this
+ * driver uses a console polling api to implement a gdb serial inteface
+ * which is multiplexed on a console port.
+ *
+ * Maintainer: Jason Wessel <jason.wessel@windriver.com>
+ *
+ * 2007-2008 (c) Jason Wessel - Wind River Systems, Inc.
+ */
+#include <linux/kernel.h>
+#include <linux/ctype.h>
+#include <linux/kgdb.h>
+#include <linux/kdb.h>
+#include <linux/tty.h>
+#include <linux/console.h>
+#include <linux/vt_kern.h>
+#include <linux/input.h>
+#include <linux/module.h>
+
+#define MAX_CONFIG_LEN		40
+
+static struct kgdb_io		kgdboc_io_ops;
+
+/* -1 = init not run yet, 0 = unconfigured, 1 = configured. */
+static int configured		= -1;
+
+static char config[MAX_CONFIG_LEN];
+static struct kparam_string kps = {
+	.string			= config,
+	.maxlen			= MAX_CONFIG_LEN,
+};
+
+static int kgdboc_use_kms;  /* 1 if we use kernel mode switching */
+static struct tty_driver	*kgdb_tty_driver;
+static int			kgdb_tty_line;
+
+#ifdef CONFIG_KDB_KEYBOARD
+static int kgdboc_reset_connect(struct input_handler *handler,
+				struct input_dev *dev,
+				const struct input_device_id *id)
+{
+	input_reset_device(dev);
+
+	/* Return an error - we do not want to bind, just to reset */
+	return -ENODEV;
+}
+
+static void kgdboc_reset_disconnect(struct input_handle *handle)
+{
+	/* We do not expect anyone to actually bind to us */
+	BUG();
+}
+
+static const struct input_device_id kgdboc_reset_ids[] = {
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
+		.evbit = { BIT_MASK(EV_KEY) },
+	},
+	{ }
+};
+
+static struct input_handler kgdboc_reset_handler = {
+	.connect	= kgdboc_reset_connect,
+	.disconnect	= kgdboc_reset_disconnect,
+	.name		= "kgdboc_reset",
+	.id_table	= kgdboc_reset_ids,
+};
+
+static DEFINE_MUTEX(kgdboc_reset_mutex);
+
+static void kgdboc_restore_input_helper(struct work_struct *dummy)
+{
+	/*
+	 * We need to take a mutex to prevent several instances of
+	 * this work running on different CPUs so they don't try
+	 * to register again already registered handler.
+	 */
+	mutex_lock(&kgdboc_reset_mutex);
+
+	if (input_register_handler(&kgdboc_reset_handler) == 0)
+		input_unregister_handler(&kgdboc_reset_handler);
+
+	mutex_unlock(&kgdboc_reset_mutex);
+}
+
+static DECLARE_WORK(kgdboc_restore_input_work, kgdboc_restore_input_helper);
+
+static void kgdboc_restore_input(void)
+{
+	if (likely(system_state == SYSTEM_RUNNING))
+		schedule_work(&kgdboc_restore_input_work);
+}
+
+static int kgdboc_register_kbd(char **cptr)
+{
+	if (strncmp(*cptr, "kbd", 3) == 0 ||
+		strncmp(*cptr, "kdb", 3) == 0) {
+		if (kdb_poll_idx < KDB_POLL_FUNC_MAX) {
+			kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char;
+			kdb_poll_idx++;
+			if (cptr[0][3] == ',')
+				*cptr += 4;
+			else
+				return 1;
+		}
+	}
+	return 0;
+}
+
+static void kgdboc_unregister_kbd(void)
+{
+	int i;
+
+	for (i = 0; i < kdb_poll_idx; i++) {
+		if (kdb_poll_funcs[i] == kdb_get_kbd_char) {
+			kdb_poll_idx--;
+			kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx];
+			kdb_poll_funcs[kdb_poll_idx] = NULL;
+			i--;
+		}
+	}
+	flush_work(&kgdboc_restore_input_work);
+}
+#else /* ! CONFIG_KDB_KEYBOARD */
+#define kgdboc_register_kbd(x) 0
+#define kgdboc_unregister_kbd()
+#define kgdboc_restore_input()
+#endif /* ! CONFIG_KDB_KEYBOARD */
+
+static void cleanup_kgdboc(void)
+{
+	if (kgdb_unregister_nmi_console())
+		return;
+	kgdboc_unregister_kbd();
+	if (configured == 1)
+		kgdb_unregister_io_module(&kgdboc_io_ops);
+}
+
+static int configure_kgdboc(void)
+{
+	struct tty_driver *p;
+	int tty_line = 0;
+	int err = -ENODEV;
+	char *cptr = config;
+	struct console *cons;
+
+	if (!strlen(config) || isspace(config[0])) {
+		err = 0;
+		goto noconfig;
+	}
+
+	kgdboc_io_ops.is_console = 0;
+	kgdb_tty_driver = NULL;
+
+	kgdboc_use_kms = 0;
+	if (strncmp(cptr, "kms,", 4) == 0) {
+		cptr += 4;
+		kgdboc_use_kms = 1;
+	}
+
+	if (kgdboc_register_kbd(&cptr))
+		goto do_register;
+
+	p = tty_find_polling_driver(cptr, &tty_line);
+	if (!p)
+		goto noconfig;
+
+	cons = console_drivers;
+	while (cons) {
+		int idx;
+		if (cons->device && cons->device(cons, &idx) == p &&
+		    idx == tty_line) {
+			kgdboc_io_ops.is_console = 1;
+			break;
+		}
+		cons = cons->next;
+	}
+
+	kgdb_tty_driver = p;
+	kgdb_tty_line = tty_line;
+
+do_register:
+	err = kgdb_register_io_module(&kgdboc_io_ops);
+	if (err)
+		goto noconfig;
+
+	err = kgdb_register_nmi_console();
+	if (err)
+		goto nmi_con_failed;
+
+	configured = 1;
+
+	return 0;
+
+nmi_con_failed:
+	kgdb_unregister_io_module(&kgdboc_io_ops);
+noconfig:
+	kgdboc_unregister_kbd();
+	config[0] = 0;
+	configured = 0;
+	cleanup_kgdboc();
+
+	return err;
+}
+
+static int __init init_kgdboc(void)
+{
+	/* Already configured? */
+	if (configured == 1)
+		return 0;
+
+	return configure_kgdboc();
+}
+
+static int kgdboc_get_char(void)
+{
+	if (!kgdb_tty_driver)
+		return -1;
+	return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver,
+						kgdb_tty_line);
+}
+
+static void kgdboc_put_char(u8 chr)
+{
+	if (!kgdb_tty_driver)
+		return;
+	kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver,
+					kgdb_tty_line, chr);
+}
+
+static int param_set_kgdboc_var(const char *kmessage,
+				const struct kernel_param *kp)
+{
+	size_t len = strlen(kmessage);
+
+	if (len >= MAX_CONFIG_LEN) {
+		printk(KERN_ERR "kgdboc: config string too long\n");
+		return -ENOSPC;
+	}
+
+	/* Only copy in the string if the init function has not run yet */
+	if (configured < 0) {
+		strcpy(config, kmessage);
+		return 0;
+	}
+
+	if (kgdb_connected) {
+		printk(KERN_ERR
+		       "kgdboc: Cannot reconfigure while KGDB is connected.\n");
+
+		return -EBUSY;
+	}
+
+	strcpy(config, kmessage);
+	/* Chop out \n char as a result of echo */
+	if (len && config[len - 1] == '\n')
+		config[len - 1] = '\0';
+
+	if (configured == 1)
+		cleanup_kgdboc();
+
+	/* Go and configure with the new params. */
+	return configure_kgdboc();
+}
+
+static int dbg_restore_graphics;
+
+static void kgdboc_pre_exp_handler(void)
+{
+	if (!dbg_restore_graphics && kgdboc_use_kms) {
+		dbg_restore_graphics = 1;
+		con_debug_enter(vc_cons[fg_console].d);
+	}
+	/* Increment the module count when the debugger is active */
+	if (!kgdb_connected)
+		try_module_get(THIS_MODULE);
+}
+
+static void kgdboc_post_exp_handler(void)
+{
+	/* decrement the module count when the debugger detaches */
+	if (!kgdb_connected)
+		module_put(THIS_MODULE);
+	if (kgdboc_use_kms && dbg_restore_graphics) {
+		dbg_restore_graphics = 0;
+		con_debug_leave();
+	}
+	kgdboc_restore_input();
+}
+
+static struct kgdb_io kgdboc_io_ops = {
+	.name			= "kgdboc",
+	.read_char		= kgdboc_get_char,
+	.write_char		= kgdboc_put_char,
+	.pre_exception		= kgdboc_pre_exp_handler,
+	.post_exception		= kgdboc_post_exp_handler,
+};
+
+#ifdef CONFIG_KGDB_SERIAL_CONSOLE
+static int kgdboc_option_setup(char *opt)
+{
+	if (!opt) {
+		pr_err("config string not provided\n");
+		return 1;
+	}
+
+	if (strlen(opt) >= MAX_CONFIG_LEN) {
+		pr_err("config string too long\n");
+		return 1;
+	}
+	strcpy(config, opt);
+
+	return 1;
+}
+
+__setup("kgdboc=", kgdboc_option_setup);
+
+
+/* This is only available if kgdboc is a built in for early debugging */
+static int __init kgdboc_early_init(char *opt)
+{
+	/* save the first character of the config string because the
+	 * init routine can destroy it.
+	 */
+	char save_ch;
+
+	kgdboc_option_setup(opt);
+	save_ch = config[0];
+	init_kgdboc();
+	config[0] = save_ch;
+	return 0;
+}
+
+early_param("ekgdboc", kgdboc_early_init);
+#endif /* CONFIG_KGDB_SERIAL_CONSOLE */
+
+module_init(init_kgdboc);
+module_exit(cleanup_kgdboc);
+module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
+MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
+MODULE_DESCRIPTION("KGDB Console TTY Driver");
+MODULE_LICENSE("GPL");