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         /* Retrun 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                 if (kdb_poll_idx < KDB_POLL_FUNC_MAX) {
 102                         kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char;
 103                         kdb_poll_idx++;
 104                         if (cptr[0][3] == ',')
 105                                 *cptr += 4;
 106                         else
 107                                 return 1;
 108                 }
 109         }
 110         return 0;
 111 }
 112
 113 static void kgdboc_unregister_kbd(void)
 114 {
 115         int i;
 116
 117         for (i = 0; i < kdb_poll_idx; i++) {
 118                 if (kdb_poll_funcs[i] == kdb_get_kbd_char) {
 119                         kdb_poll_idx--;
 120                         kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx];
 121                         kdb_poll_funcs[kdb_poll_idx] = NULL;
 122                         i--;
 123                 }
 124         }
 125         flush_work_sync(&kgdboc_restore_input_work);
 126 }
 127 #else /* ! CONFIG_KDB_KEYBOARD */
 128 #define kgdboc_register_kbd(x) 0
 129 #define kgdboc_unregister_kbd()
 130 #define kgdboc_restore_input()
 131 #endif /* ! CONFIG_KDB_KEYBOARD */
 132
 133 static int kgdboc_option_setup(char *opt)
 134 {
 135         if (strlen(opt) >= MAX_CONFIG_LEN) {
 136                 printk(KERN_ERR "kgdboc: config string too long\n");
 137                 return -ENOSPC;
 138         }
 139         strcpy(config, opt);
 140
 141         return 0;
 142 }
 143
 144 __setup("kgdboc=", kgdboc_option_setup);
 145
 146 static void cleanup_kgdboc(void)
 147 {
 148         kgdboc_unregister_kbd();
 149         if (configured == 1)
 150                 kgdb_unregister_io_module(&kgdboc_io_ops);
 151 }
 152
 153 static int configure_kgdboc(void)
 154 {
 155         struct tty_driver *p;
 156         int tty_line = 0;
 157         int err;
 158         char *cptr = config;
 159         struct console *cons;
 160
 161         err = kgdboc_option_setup(config);
 162         if (err || !strlen(config) || isspace(config[0]))
 163                 goto noconfig;
 164
 165         err = -ENODEV;
 166         kgdboc_io_ops.is_console = 0;
 167         kgdb_tty_driver = NULL;
 168
 169         kgdboc_use_kms = 0;
 170         if (strncmp(cptr, "kms,", 4) == 0) {
 171                 cptr += 4;
 172                 kgdboc_use_kms = 1;
 173         }
 174
 175         if (kgdboc_register_kbd(&cptr))
 176                 goto do_register;
 177
 178         p = tty_find_polling_driver(cptr, &tty_line);
 179         if (!p)
 180                 goto noconfig;
 181
 182         cons = console_drivers;
 183         while (cons) {
 184                 int idx;
 185                 if (cons->device && cons->device(cons, &idx) == p &&
 186                     idx == tty_line) {
 187                         kgdboc_io_ops.is_console = 1;
 188                         break;
 189                 }
 190                 cons = cons->next;
 191         }
 192
 193         kgdb_tty_driver = p;
 194         kgdb_tty_line = tty_line;
 195
 196 do_register:
 197         err = kgdb_register_io_module(&kgdboc_io_ops);
 198         if (err)
 199                 goto noconfig;
 200
 201         configured = 1;
 202
 203         return 0;
 204
 205 noconfig:
 206         config[0] = 0;
 207         configured = 0;
 208         cleanup_kgdboc();
 209
 210         return err;
 211 }
 212
 213 static int __init init_kgdboc(void)
 214 {
 215         /* Already configured? */
 216         if (configured == 1)
 217                 return 0;
 218
 219         return configure_kgdboc();
 220 }
 221
 222 static int kgdboc_get_char(void)
 223 {
 224         if (!kgdb_tty_driver)
 225                 return -1;
 226         return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver,
 227                                                 kgdb_tty_line);
 228 }
 229
 230 static void kgdboc_put_char(u8 chr)
 231 {
 232         if (!kgdb_tty_driver)
 233                 return;
 234         kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver,
 235                                         kgdb_tty_line, chr);
 236 }
 237
 238 static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)
 239 {
 240         int len = strlen(kmessage);
 241
 242         if (len >= MAX_CONFIG_LEN) {
 243                 printk(KERN_ERR "kgdboc: config string too long\n");
 244                 return -ENOSPC;
 245         }
 246
 247         /* Only copy in the string if the init function has not run yet */
 248         if (configured < 0) {
 249                 strcpy(config, kmessage);
 250                 return 0;
 251         }
 252
 253         if (kgdb_connected) {
 254                 printk(KERN_ERR
 255                        "kgdboc: Cannot reconfigure while KGDB is connected.\n");
 256
 257                 return -EBUSY;
 258         }
 259
 260         strcpy(config, kmessage);
 261         /* Chop out \n char as a result of echo */
 262         if (config[len - 1] == '\n')
 263                 config[len - 1] = '\0';
 264
 265         if (configured == 1)
 266                 cleanup_kgdboc();
 267
 268         /* Go and configure with the new params. */
 269         return configure_kgdboc();
 270 }
 271
 272 static int dbg_restore_graphics;
 273
 274 static void kgdboc_pre_exp_handler(void)
 275 {
 276         if (!dbg_restore_graphics && kgdboc_use_kms) {
 277                 dbg_restore_graphics = 1;
 278                 con_debug_enter(vc_cons[fg_console].d);
 279         }
 280         /* Increment the module count when the debugger is active */
 281         if (!kgdb_connected)
 282                 try_module_get(THIS_MODULE);
 283 }
 284
 285 static void kgdboc_post_exp_handler(void)
 286 {
 287         /* decrement the module count when the debugger detaches */
 288         if (!kgdb_connected)
 289                 module_put(THIS_MODULE);
 290         if (kgdboc_use_kms && dbg_restore_graphics) {
 291                 dbg_restore_graphics = 0;
 292                 con_debug_leave();
 293         }
 294         kgdboc_restore_input();
 295 }
 296
 297 static struct kgdb_io kgdboc_io_ops = {
 298         .name                   = "kgdboc",
 299         .read_char              = kgdboc_get_char,
 300         .write_char             = kgdboc_put_char,
 301         .pre_exception          = kgdboc_pre_exp_handler,
 302         .post_exception         = kgdboc_post_exp_handler,
 303 };
 304
 305 #ifdef CONFIG_KGDB_SERIAL_CONSOLE
 306 /* This is only available if kgdboc is a built in for early debugging */
 307 static int __init kgdboc_early_init(char *opt)
 308 {
 309         /* save the first character of the config string because the
 310          * init routine can destroy it.
 311          */
 312         char save_ch;
 313
 314         kgdboc_option_setup(opt);
 315         save_ch = config[0];
 316         init_kgdboc();
 317         config[0] = save_ch;
 318         return 0;
 319 }
 320
 321 early_param("ekgdboc", kgdboc_early_init);
 322 #endif /* CONFIG_KGDB_SERIAL_CONSOLE */
 323
 324 module_init(init_kgdboc);
 325 module_exit(cleanup_kgdboc);
 326 module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
 327 MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
 328 MODULE_DESCRIPTION("KGDB Console TTY Driver");
 329 MODULE_LICENSE("GPL");