aboutsummaryrefslogtreecommitdiff
path: root/drivers/serial/kgdboc.c
blob: 3374618300af87c16ac3ef6a674e9cb650e62f8c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
/*
 * 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/kdb.h>
#include <linux/tty.h>
#include <linux/console.h>
#include <linux/vt_kern.h>
#include <linux/input.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);

	/* Retrun 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)
{
	schedule_work(&kgdboc_restore_input_work);
}

static int kgdboc_register_kbd(char **cptr)
{
	if (strncmp(*cptr, "kbd", 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_sync(&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 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 void cleanup_kgdboc(void)
{
	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;
	char *cptr = config;
	struct console *cons;

	err = kgdboc_option_setup(config);
	if (err || !strlen(config) || isspace(config[0]))
		goto noconfig;

	err = -ENODEV;
	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;

	configured = 1;

	return 0;

noconfig:
	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, struct kernel_param *kp)
{
	int 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 (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
/* 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");