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Linux/drivers/tty/serial/kgdboc.c

  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/kdb.h>
 18 #include <linux/tty.h>
 19 #include <linux/console.h>
 20 #include <linux/vt_kern.h>
 21 #include <linux/input.h>
 22 #include <linux/module.h>
 23 
 24 #define MAX_CONFIG_LEN          40
 25 
 26 static struct kgdb_io           kgdboc_io_ops;
 27 
 28 /* -1 = init not run yet, 0 = unconfigured, 1 = configured. */
 29 static int configured           = -1;
 30 
 31 static char config[MAX_CONFIG_LEN];
 32 static struct kparam_string kps = {
 33         .string                 = config,
 34         .maxlen                 = MAX_CONFIG_LEN,
 35 };
 36 
 37 static int kgdboc_use_kms;  /* 1 if we use kernel mode switching */
 38 static struct tty_driver        *kgdb_tty_driver;
 39 static int                      kgdb_tty_line;
 40 
 41 #ifdef CONFIG_KDB_KEYBOARD
 42 static int kgdboc_reset_connect(struct input_handler *handler,
 43                                 struct input_dev *dev,
 44                                 const struct input_device_id *id)
 45 {
 46         input_reset_device(dev);
 47 
 48         /* Return an error - we do not want to bind, just to reset */
 49         return -ENODEV;
 50 }
 51 
 52 static void kgdboc_reset_disconnect(struct input_handle *handle)
 53 {
 54         /* We do not expect anyone to actually bind to us */
 55         BUG();
 56 }
 57 
 58 static const struct input_device_id kgdboc_reset_ids[] = {
 59         {
 60                 .flags = INPUT_DEVICE_ID_MATCH_EVBIT,
 61                 .evbit = { BIT_MASK(EV_KEY) },
 62         },
 63         { }
 64 };
 65 
 66 static struct input_handler kgdboc_reset_handler = {
 67         .connect        = kgdboc_reset_connect,
 68         .disconnect     = kgdboc_reset_disconnect,
 69         .name           = "kgdboc_reset",
 70         .id_table       = kgdboc_reset_ids,
 71 };
 72 
 73 static DEFINE_MUTEX(kgdboc_reset_mutex);
 74 
 75 static void kgdboc_restore_input_helper(struct work_struct *dummy)
 76 {
 77         /*
 78          * We need to take a mutex to prevent several instances of
 79          * this work running on different CPUs so they don't try
 80          * to register again already registered handler.
 81          */
 82         mutex_lock(&kgdboc_reset_mutex);
 83 
 84         if (input_register_handler(&kgdboc_reset_handler) == 0)
 85                 input_unregister_handler(&kgdboc_reset_handler);
 86 
 87         mutex_unlock(&kgdboc_reset_mutex);
 88 }
 89 
 90 static DECLARE_WORK(kgdboc_restore_input_work, kgdboc_restore_input_helper);
 91 
 92 static void kgdboc_restore_input(void)
 93 {
 94         if (likely(system_state == SYSTEM_RUNNING))
 95                 schedule_work(&kgdboc_restore_input_work);
 96 }
 97 
 98 static int kgdboc_register_kbd(char **cptr)
 99 {
100         if (strncmp(*cptr, "kbd", 3) == 0 ||
101                 strncmp(*cptr, "kdb", 3) == 0) {
102                 if (kdb_poll_idx < KDB_POLL_FUNC_MAX) {
103                         kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char;
104                         kdb_poll_idx++;
105                         if (cptr[0][3] == ',')
106                                 *cptr += 4;
107                         else
108                                 return 1;
109                 }
110         }
111         return 0;
112 }
113 
114 static void kgdboc_unregister_kbd(void)
115 {
116         int i;
117 
118         for (i = 0; i < kdb_poll_idx; i++) {
119                 if (kdb_poll_funcs[i] == kdb_get_kbd_char) {
120                         kdb_poll_idx--;
121                         kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx];
122                         kdb_poll_funcs[kdb_poll_idx] = NULL;
123                         i--;
124                 }
125         }
126         flush_work(&kgdboc_restore_input_work);
127 }
128 #else /* ! CONFIG_KDB_KEYBOARD */
129 #define kgdboc_register_kbd(x) 0
130 #define kgdboc_unregister_kbd()
131 #define kgdboc_restore_input()
132 #endif /* ! CONFIG_KDB_KEYBOARD */
133 
134 static int kgdboc_option_setup(char *opt)
135 {
136         if (strlen(opt) >= MAX_CONFIG_LEN) {
137                 printk(KERN_ERR "kgdboc: config string too long\n");
138                 return -ENOSPC;
139         }
140         strcpy(config, opt);
141 
142         return 0;
143 }
144 
145 __setup("kgdboc=", kgdboc_option_setup);
146 
147 static void cleanup_kgdboc(void)
148 {
149         if (kgdb_unregister_nmi_console())
150                 return;
151         kgdboc_unregister_kbd();
152         if (configured == 1)
153                 kgdb_unregister_io_module(&kgdboc_io_ops);
154 }
155 
156 static int configure_kgdboc(void)
157 {
158         struct tty_driver *p;
159         int tty_line = 0;
160         int err;
161         char *cptr = config;
162         struct console *cons;
163 
164         err = kgdboc_option_setup(config);
165         if (err || !strlen(config) || isspace(config[0]))
166                 goto noconfig;
167 
168         err = -ENODEV;
169         kgdboc_io_ops.is_console = 0;
170         kgdb_tty_driver = NULL;
171 
172         kgdboc_use_kms = 0;
173         if (strncmp(cptr, "kms,", 4) == 0) {
174                 cptr += 4;
175                 kgdboc_use_kms = 1;
176         }
177 
178         if (kgdboc_register_kbd(&cptr))
179                 goto do_register;
180 
181         p = tty_find_polling_driver(cptr, &tty_line);
182         if (!p)
183                 goto noconfig;
184 
185         cons = console_drivers;
186         while (cons) {
187                 int idx;
188                 if (cons->device && cons->device(cons, &idx) == p &&
189                     idx == tty_line) {
190                         kgdboc_io_ops.is_console = 1;
191                         break;
192                 }
193                 cons = cons->next;
194         }
195 
196         kgdb_tty_driver = p;
197         kgdb_tty_line = tty_line;
198 
199 do_register:
200         err = kgdb_register_io_module(&kgdboc_io_ops);
201         if (err)
202                 goto noconfig;
203 
204         err = kgdb_register_nmi_console();
205         if (err)
206                 goto nmi_con_failed;
207 
208         configured = 1;
209 
210         return 0;
211 
212 nmi_con_failed:
213         kgdb_unregister_io_module(&kgdboc_io_ops);
214 noconfig:
215         kgdboc_unregister_kbd();
216         config[0] = 0;
217         configured = 0;
218         cleanup_kgdboc();
219 
220         return err;
221 }
222 
223 static int __init init_kgdboc(void)
224 {
225         /* Already configured? */
226         if (configured == 1)
227                 return 0;
228 
229         return configure_kgdboc();
230 }
231 
232 static int kgdboc_get_char(void)
233 {
234         if (!kgdb_tty_driver)
235                 return -1;
236         return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver,
237                                                 kgdb_tty_line);
238 }
239 
240 static void kgdboc_put_char(u8 chr)
241 {
242         if (!kgdb_tty_driver)
243                 return;
244         kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver,
245                                         kgdb_tty_line, chr);
246 }
247 
248 static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)
249 {
250         int len = strlen(kmessage);
251 
252         if (len >= MAX_CONFIG_LEN) {
253                 printk(KERN_ERR "kgdboc: config string too long\n");
254                 return -ENOSPC;
255         }
256 
257         /* Only copy in the string if the init function has not run yet */
258         if (configured < 0) {
259                 strcpy(config, kmessage);
260                 return 0;
261         }
262 
263         if (kgdb_connected) {
264                 printk(KERN_ERR
265                        "kgdboc: Cannot reconfigure while KGDB is connected.\n");
266 
267                 return -EBUSY;
268         }
269 
270         strcpy(config, kmessage);
271         /* Chop out \n char as a result of echo */
272         if (config[len - 1] == '\n')
273                 config[len - 1] = '\0';
274 
275         if (configured == 1)
276                 cleanup_kgdboc();
277 
278         /* Go and configure with the new params. */
279         return configure_kgdboc();
280 }
281 
282 static int dbg_restore_graphics;
283 
284 static void kgdboc_pre_exp_handler(void)
285 {
286         if (!dbg_restore_graphics && kgdboc_use_kms) {
287                 dbg_restore_graphics = 1;
288                 con_debug_enter(vc_cons[fg_console].d);
289         }
290         /* Increment the module count when the debugger is active */
291         if (!kgdb_connected)
292                 try_module_get(THIS_MODULE);
293 }
294 
295 static void kgdboc_post_exp_handler(void)
296 {
297         /* decrement the module count when the debugger detaches */
298         if (!kgdb_connected)
299                 module_put(THIS_MODULE);
300         if (kgdboc_use_kms && dbg_restore_graphics) {
301                 dbg_restore_graphics = 0;
302                 con_debug_leave();
303         }
304         kgdboc_restore_input();
305 }
306 
307 static struct kgdb_io kgdboc_io_ops = {
308         .name                   = "kgdboc",
309         .read_char              = kgdboc_get_char,
310         .write_char             = kgdboc_put_char,
311         .pre_exception          = kgdboc_pre_exp_handler,
312         .post_exception         = kgdboc_post_exp_handler,
313 };
314 
315 #ifdef CONFIG_KGDB_SERIAL_CONSOLE
316 /* This is only available if kgdboc is a built in for early debugging */
317 static int __init kgdboc_early_init(char *opt)
318 {
319         /* save the first character of the config string because the
320          * init routine can destroy it.
321          */
322         char save_ch;
323 
324         kgdboc_option_setup(opt);
325         save_ch = config[0];
326         init_kgdboc();
327         config[0] = save_ch;
328         return 0;
329 }
330 
331 early_param("ekgdboc", kgdboc_early_init);
332 #endif /* CONFIG_KGDB_SERIAL_CONSOLE */
333 
334 module_init(init_kgdboc);
335 module_exit(cleanup_kgdboc);
336 module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
337 MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
338 MODULE_DESCRIPTION("KGDB Console TTY Driver");
339 MODULE_LICENSE("GPL");
340 

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