drivers/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         schedule_work(&kgdboc_restore_input_work);
  94 }
  95
  96 static int kgdboc_register_kbd(char **cptr)
  97 {
  98         if (strncmp(*cptr, "kbd", 3) == 0) {
  99                 if (kdb_poll_idx < KDB_POLL_FUNC_MAX) {
 100                         kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char;
 101                         kdb_poll_idx++;
 102                         if (cptr[0][3] == ',')
 103                                 *cptr += 4;
 104                         else
 105                                 return 1;
 106                 }
 107         }
 108         return 0;
 109 }
 110
 111 static void kgdboc_unregister_kbd(void)
 112 {
 113         int i;
 114
 115         for (i = 0; i < kdb_poll_idx; i++) {
 116                 if (kdb_poll_funcs[i] == kdb_get_kbd_char) {
 117                         kdb_poll_idx--;
 118                         kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx];
 119                         kdb_poll_funcs[kdb_poll_idx] = NULL;
 120                         i--;
 121                 }
 122         }
 123         flush_work_sync(&kgdboc_restore_input_work);
 124 }
 125 #else /* ! CONFIG_KDB_KEYBOARD */
 126 #define kgdboc_register_kbd(x) 0
 127 #define kgdboc_unregister_kbd()
 128 #define kgdboc_restore_input()
 129 #endif /* ! CONFIG_KDB_KEYBOARD */
 130
 131 static int kgdboc_option_setup(char *opt)
 132 {
 133         if (strlen(opt) > MAX_CONFIG_LEN) {
 134                 printk(KERN_ERR "kgdboc: config string too long\n");
 135                 return -ENOSPC;
 136         }
 137         strcpy(config, opt);
 138
 139         return 0;
 140 }
 141
 142 __setup("kgdboc=", kgdboc_option_setup);
 143
 144 static void cleanup_kgdboc(void)
 145 {
 146         kgdboc_unregister_kbd();
 147         if (configured == 1)
 148                 kgdb_unregister_io_module(&kgdboc_io_ops);
 149 }
 150
 151 static int configure_kgdboc(void)
 152 {
 153         struct tty_driver *p;
 154         int tty_line = 0;
 155         int err;
 156         char *cptr = config;
 157         struct console *cons;
 158
 159         err = kgdboc_option_setup(config);
 160         if (err || !strlen(config) || isspace(config[0]))
 161                 goto noconfig;
 162
 163         err = -ENODEV;
 164         kgdboc_io_ops.is_console = 0;
 165         kgdb_tty_driver = NULL;
 166
 167         kgdboc_use_kms = 0;
 168         if (strncmp(cptr, "kms,", 4) == 0) {
 169                 cptr += 4;
 170                 kgdboc_use_kms = 1;
 171         }
 172
 173         if (kgdboc_register_kbd(&cptr))
 174                 goto do_register;
 175
 176         p = tty_find_polling_driver(cptr, &tty_line);
 177         if (!p)
 178                 goto noconfig;
 179
 180         cons = console_drivers;
 181         while (cons) {
 182                 int idx;
 183                 if (cons->device && cons->device(cons, &idx) == p &&
 184                     idx == tty_line) {
 185                         kgdboc_io_ops.is_console = 1;
 186                         break;
 187                 }
 188                 cons = cons->next;
 189         }
 190
 191         kgdb_tty_driver = p;
 192         kgdb_tty_line = tty_line;
 193
 194 do_register:
 195         err = kgdb_register_io_module(&kgdboc_io_ops);
 196         if (err)
 197                 goto noconfig;
 198
 199         configured = 1;
 200
 201         return 0;
 202
 203 noconfig:
 204         config[0] = 0;
 205         configured = 0;
 206         cleanup_kgdboc();
 207
 208         return err;
 209 }
 210
 211 static int __init init_kgdboc(void)
 212 {
 213         /* Already configured? */
 214         if (configured == 1)
 215                 return 0;
 216
 217         return configure_kgdboc();
 218 }
 219
 220 static int kgdboc_get_char(void)
 221 {
 222         if (!kgdb_tty_driver)
 223                 return -1;
 224         return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver,
 225                                                 kgdb_tty_line);
 226 }
 227
 228 static void kgdboc_put_char(u8 chr)
 229 {
 230         if (!kgdb_tty_driver)
 231                 return;
 232         kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver,
 233                                         kgdb_tty_line, chr);
 234 }
 235
 236 static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)
 237 {
 238         int len = strlen(kmessage);
 239
 240         if (len >= MAX_CONFIG_LEN) {
 241                 printk(KERN_ERR "kgdboc: config string too long\n");
 242                 return -ENOSPC;
 243         }
 244
 245         /* Only copy in the string if the init function has not run yet */
 246         if (configured < 0) {
 247                 strcpy(config, kmessage);
 248                 return 0;
 249         }
 250
 251         if (kgdb_connected) {
 252                 printk(KERN_ERR
 253                        "kgdboc: Cannot reconfigure while KGDB is connected.\n");
 254
 255                 return -EBUSY;
 256         }
 257
 258         strcpy(config, kmessage);
 259         /* Chop out \n char as a result of echo */
 260         if (config[len - 1] == '\n')
 261                 config[len - 1] = '\0';
 262
 263         if (configured == 1)
 264                 cleanup_kgdboc();
 265
 266         /* Go and configure with the new params. */
 267         return configure_kgdboc();
 268 }
 269
 270 static int dbg_restore_graphics;
 271
 272 static void kgdboc_pre_exp_handler(void)
 273 {
 274         if (!dbg_restore_graphics && kgdboc_use_kms) {
 275                 dbg_restore_graphics = 1;
 276                 con_debug_enter(vc_cons[fg_console].d);
 277         }
 278         /* Increment the module count when the debugger is active */
 279         if (!kgdb_connected)
 280                 try_module_get(THIS_MODULE);
 281 }
 282
 283 static void kgdboc_post_exp_handler(void)
 284 {
 285         /* decrement the module count when the debugger detaches */
 286         if (!kgdb_connected)
 287                 module_put(THIS_MODULE);
 288         if (kgdboc_use_kms && dbg_restore_graphics) {
 289                 dbg_restore_graphics = 0;
 290                 con_debug_leave();
 291         }
 292         kgdboc_restore_input();
 293 }
 294
 295 static struct kgdb_io kgdboc_io_ops = {
 296         .name                   = "kgdboc",
 297         .read_char              = kgdboc_get_char,
 298         .write_char             = kgdboc_put_char,
 299         .pre_exception          = kgdboc_pre_exp_handler,
 300         .post_exception         = kgdboc_post_exp_handler,
 301 };
 302
 303 #ifdef CONFIG_KGDB_SERIAL_CONSOLE
 304 /* This is only available if kgdboc is a built in for early debugging */
 305 static int __init kgdboc_early_init(char *opt)
 306 {
 307         /* save the first character of the config string because the
 308          * init routine can destroy it.
 309          */
 310         char save_ch;
 311
 312         kgdboc_option_setup(opt);
 313         save_ch = config[0];
 314         init_kgdboc();
 315         config[0] = save_ch;
 316         return 0;
 317 }
 318
 319 early_param("ekgdboc", kgdboc_early_init);
 320 #endif /* CONFIG_KGDB_SERIAL_CONSOLE */
 321
 322 module_init(init_kgdboc);
 323 module_exit(cleanup_kgdboc);
 324 module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
 325 MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
 326 MODULE_DESCRIPTION("KGDB Console TTY Driver");
 327 MODULE_LICENSE("GPL");