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");