f2d937f3bf
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>
163 lines
3.5 KiB
C
163 lines
3.5 KiB
C
/*
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* Based on the same principle as kgdboe using the NETPOLL api, this
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* driver uses a console polling api to implement a gdb serial inteface
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* which is multiplexed on a console port.
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*
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* Maintainer: Jason Wessel <jason.wessel@windriver.com>
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*
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* 2007-2008 (c) Jason Wessel - Wind River Systems, Inc.
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <linux/kernel.h>
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#include <linux/ctype.h>
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#include <linux/kgdb.h>
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#include <linux/tty.h>
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#define MAX_CONFIG_LEN 40
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static struct kgdb_io kgdboc_io_ops;
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/* -1 = init not run yet, 0 = unconfigured, 1 = configured. */
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static int configured = -1;
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static char config[MAX_CONFIG_LEN];
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static struct kparam_string kps = {
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.string = config,
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.maxlen = MAX_CONFIG_LEN,
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};
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static struct tty_driver *kgdb_tty_driver;
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static int kgdb_tty_line;
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static int kgdboc_option_setup(char *opt)
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{
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if (strlen(opt) > MAX_CONFIG_LEN) {
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printk(KERN_ERR "kgdboc: config string too long\n");
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return -ENOSPC;
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}
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strcpy(config, opt);
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return 0;
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}
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__setup("kgdboc=", kgdboc_option_setup);
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static int configure_kgdboc(void)
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{
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struct tty_driver *p;
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int tty_line = 0;
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int err;
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err = kgdboc_option_setup(config);
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if (err || !strlen(config) || isspace(config[0]))
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goto noconfig;
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err = -ENODEV;
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p = tty_find_polling_driver(config, &tty_line);
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if (!p)
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goto noconfig;
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kgdb_tty_driver = p;
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kgdb_tty_line = tty_line;
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err = kgdb_register_io_module(&kgdboc_io_ops);
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if (err)
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goto noconfig;
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configured = 1;
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return 0;
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noconfig:
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config[0] = 0;
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configured = 0;
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return err;
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}
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static int __init init_kgdboc(void)
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{
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/* Already configured? */
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if (configured == 1)
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return 0;
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return configure_kgdboc();
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}
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static void cleanup_kgdboc(void)
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{
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if (configured == 1)
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kgdb_unregister_io_module(&kgdboc_io_ops);
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}
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static int kgdboc_get_char(void)
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{
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return kgdb_tty_driver->poll_get_char(kgdb_tty_driver, kgdb_tty_line);
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}
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static void kgdboc_put_char(u8 chr)
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{
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kgdb_tty_driver->poll_put_char(kgdb_tty_driver, kgdb_tty_line, chr);
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}
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static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)
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{
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if (strlen(kmessage) >= MAX_CONFIG_LEN) {
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printk(KERN_ERR "kgdboc: config string too long\n");
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return -ENOSPC;
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}
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/* Only copy in the string if the init function has not run yet */
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if (configured < 0) {
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strcpy(config, kmessage);
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return 0;
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}
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if (kgdb_connected) {
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printk(KERN_ERR
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"kgdboc: Cannot reconfigure while KGDB is connected.\n");
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return -EBUSY;
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}
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strcpy(config, kmessage);
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if (configured == 1)
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cleanup_kgdboc();
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/* Go and configure with the new params. */
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return configure_kgdboc();
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}
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static void kgdboc_pre_exp_handler(void)
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{
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/* Increment the module count when the debugger is active */
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if (!kgdb_connected)
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try_module_get(THIS_MODULE);
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}
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static void kgdboc_post_exp_handler(void)
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{
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/* decrement the module count when the debugger detaches */
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if (!kgdb_connected)
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module_put(THIS_MODULE);
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}
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static struct kgdb_io kgdboc_io_ops = {
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.name = "kgdboc",
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.read_char = kgdboc_get_char,
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.write_char = kgdboc_put_char,
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.pre_exception = kgdboc_pre_exp_handler,
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.post_exception = kgdboc_post_exp_handler,
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};
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module_init(init_kgdboc);
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module_exit(cleanup_kgdboc);
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module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
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MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
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MODULE_DESCRIPTION("KGDB Console TTY Driver");
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MODULE_LICENSE("GPL");
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