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