tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Based on the same principle as kgdboe using the NETPOLL api, this
3 * driver uses a console polling api to implement a gdb serial inteface
4 * which is multiplexed on a console port.
5 *
6 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
7 *
8 * 2007-2008 (c) Jason Wessel - Wind River Systems, Inc.
9 *
10 * This file is licensed under the terms of the GNU General Public
11 * License version 2. This program is licensed "as is" without any
12 * warranty of any kind, whether express or implied.
13 */
14#include <linux/kernel.h>
15#include <linux/ctype.h>
16#include <linux/kgdb.h>
17#include <linux/tty.h>
18
19#define MAX_CONFIG_LEN 40
20
21static struct kgdb_io kgdboc_io_ops;
22
23/* -1 = init not run yet, 0 = unconfigured, 1 = configured. */
24static int configured = -1;
25
26static char config[MAX_CONFIG_LEN];
27static struct kparam_string kps = {
28 .string = config,
29 .maxlen = MAX_CONFIG_LEN,
30};
31
32static struct tty_driver *kgdb_tty_driver;
33static int kgdb_tty_line;
34
35static int kgdboc_option_setup(char *opt)
36{
37 if (strlen(opt) > MAX_CONFIG_LEN) {
38 printk(KERN_ERR "kgdboc: config string too long\n");
39 return -ENOSPC;
40 }
41 strcpy(config, opt);
42
43 return 0;
44}
45
46__setup("kgdboc=", kgdboc_option_setup);
47
48static int configure_kgdboc(void)
49{
50 struct tty_driver *p;
51 int tty_line = 0;
52 int err;
53
54 err = kgdboc_option_setup(config);
55 if (err || !strlen(config) || isspace(config[0]))
56 goto noconfig;
57
58 err = -ENODEV;
59
60 p = tty_find_polling_driver(config, &tty_line);
61 if (!p)
62 goto noconfig;
63
64 kgdb_tty_driver = p;
65 kgdb_tty_line = tty_line;
66
67 err = kgdb_register_io_module(&kgdboc_io_ops);
68 if (err)
69 goto noconfig;
70
71 configured = 1;
72
73 return 0;
74
75noconfig:
76 config[0] = 0;
77 configured = 0;
78
79 return err;
80}
81
82static int __init init_kgdboc(void)
83{
84 /* Already configured? */
85 if (configured == 1)
86 return 0;
87
88 return configure_kgdboc();
89}
90
91static void cleanup_kgdboc(void)
92{
93 if (configured == 1)
94 kgdb_unregister_io_module(&kgdboc_io_ops);
95}
96
97static int kgdboc_get_char(void)
98{
99 return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver,
100 kgdb_tty_line);
101}
102
103static void kgdboc_put_char(u8 chr)
104{
105 kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver,
106 kgdb_tty_line, chr);
107}
108
109static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)
110{
111 int len = strlen(kmessage);
112
113 if (len >= MAX_CONFIG_LEN) {
114 printk(KERN_ERR "kgdboc: config string too long\n");
115 return -ENOSPC;
116 }
117
118 /* Only copy in the string if the init function has not run yet */
119 if (configured < 0) {
120 strcpy(config, kmessage);
121 return 0;
122 }
123
124 if (kgdb_connected) {
125 printk(KERN_ERR
126 "kgdboc: Cannot reconfigure while KGDB is connected.\n");
127
128 return -EBUSY;
129 }
130
131 strcpy(config, kmessage);
132 /* Chop out \n char as a result of echo */
133 if (config[len - 1] == '\n')
134 config[len - 1] = '\0';
135
136 if (configured == 1)
137 cleanup_kgdboc();
138
139 /* Go and configure with the new params. */
140 return configure_kgdboc();
141}
142
143static void kgdboc_pre_exp_handler(void)
144{
145 /* Increment the module count when the debugger is active */
146 if (!kgdb_connected)
147 try_module_get(THIS_MODULE);
148}
149
150static void kgdboc_post_exp_handler(void)
151{
152 /* decrement the module count when the debugger detaches */
153 if (!kgdb_connected)
154 module_put(THIS_MODULE);
155}
156
157static struct kgdb_io kgdboc_io_ops = {
158 .name = "kgdboc",
159 .read_char = kgdboc_get_char,
160 .write_char = kgdboc_put_char,
161 .pre_exception = kgdboc_pre_exp_handler,
162 .post_exception = kgdboc_post_exp_handler,
163};
164
165module_init(init_kgdboc);
166module_exit(cleanup_kgdboc);
167module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
168MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
169MODULE_DESCRIPTION("KGDB Console TTY Driver");
170MODULE_LICENSE("GPL");