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authorJason Wessel <jason.wessel@windriver.com>2008-04-17 20:05:37 +0200
committerIngo Molnar <mingo@elte.hu>2008-04-17 20:05:37 +0200
commitf2d937f3bf00665ccf048b3b6616ef95859b0945 (patch)
tree6136ded0706be0d39a09a0a912e8f79a4ab63322 /drivers/serial/kgdboc.c
parentdc7d552705215ac50a0617fcf51bb9c736255b8e (diff)
consoles: polling support, kgdboc
polled console handling support, to access a console in an irq-less way while in debug or irq context. absolutely zero impact as long as CONFIG_CONSOLE_POLL is disabled. (which is the default) [ jan.kiszka@siemens.com: lots of cleanups ] [ mingo@elte.hu: redesign, splitups, cleanups. ] Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Jan Kiszka <jan.kiszka@web.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'drivers/serial/kgdboc.c')
-rw-r--r--drivers/serial/kgdboc.c163
1 files changed, 163 insertions, 0 deletions
diff --git a/drivers/serial/kgdboc.c b/drivers/serial/kgdboc.c
new file mode 100644
index 000000000000..341830791608
--- /dev/null
+++ b/drivers/serial/kgdboc.c
@@ -0,0 +1,163 @@
+/*
+ * 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.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+#include <linux/kernel.h>
+#include <linux/ctype.h>
+#include <linux/kgdb.h>
+#include <linux/tty.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 struct tty_driver *kgdb_tty_driver;
+static int kgdb_tty_line;
+
+static int kgdboc_option_setup(char *opt)
+{
+ if (strlen(opt) > MAX_CONFIG_LEN) {
+ printk(KERN_ERR "kgdboc: config string too long\n");
+ return -ENOSPC;
+ }
+ strcpy(config, opt);
+
+ return 0;
+}
+
+__setup("kgdboc=", kgdboc_option_setup);
+
+static int configure_kgdboc(void)
+{
+ struct tty_driver *p;
+ int tty_line = 0;
+ int err;
+
+ err = kgdboc_option_setup(config);
+ if (err || !strlen(config) || isspace(config[0]))
+ goto noconfig;
+
+ err = -ENODEV;
+
+ p = tty_find_polling_driver(config, &tty_line);
+ if (!p)
+ goto noconfig;
+
+ kgdb_tty_driver = p;
+ kgdb_tty_line = tty_line;
+
+ err = kgdb_register_io_module(&kgdboc_io_ops);
+ if (err)
+ goto noconfig;
+
+ configured = 1;
+
+ return 0;
+
+noconfig:
+ config[0] = 0;
+ configured = 0;
+
+ return err;
+}
+
+static int __init init_kgdboc(void)
+{
+ /* Already configured? */
+ if (configured == 1)
+ return 0;
+
+ return configure_kgdboc();
+}
+
+static void cleanup_kgdboc(void)
+{
+ if (configured == 1)
+ kgdb_unregister_io_module(&kgdboc_io_ops);
+}
+
+static int kgdboc_get_char(void)
+{
+ return kgdb_tty_driver->poll_get_char(kgdb_tty_driver, kgdb_tty_line);
+}
+
+static void kgdboc_put_char(u8 chr)
+{
+ kgdb_tty_driver->poll_put_char(kgdb_tty_driver, kgdb_tty_line, chr);
+}
+
+static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)
+{
+ if (strlen(kmessage) >= 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);
+
+ if (configured == 1)
+ cleanup_kgdboc();
+
+ /* Go and configure with the new params. */
+ return configure_kgdboc();
+}
+
+static void kgdboc_pre_exp_handler(void)
+{
+ /* 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);
+}
+
+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,
+};
+
+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");