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
  22 #define MAX_CONFIG_LEN          40
  23
  24 static struct kgdb_io           kgdboc_io_ops;
  25
  26 /* -1 = init not run yet, 0 = unconfigured, 1 = configured. */
  27 static int configured           = -1;
  28
  29 static char config[MAX_CONFIG_LEN];
  30 static struct kparam_string kps = {
  31         .string                 = config,
  32         .maxlen                 = MAX_CONFIG_LEN,
  33 };
  34
  35 static int kgdboc_use_kms;  /* 1 if we use kernel mode switching */
  36 static struct tty_driver        *kgdb_tty_driver;
  37 static int                      kgdb_tty_line;
  38
  39 #ifdef CONFIG_KDB_KEYBOARD
  40 static int kgdboc_register_kbd(char **cptr)
  41 {
  42         if (strncmp(*cptr, "kbd", 3) == 0) {
  43                 if (kdb_poll_idx < KDB_POLL_FUNC_MAX) {
  44                         kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char;
  45                         kdb_poll_idx++;
  46                         if (cptr[0][3] == ',')
  47                                 *cptr += 4;
  48                         else
  49                                 return 1;
  50                 }
  51         }
  52         return 0;
  53 }
  54
  55 static void kgdboc_unregister_kbd(void)
  56 {
  57         int i;
  58
  59         for (i = 0; i < kdb_poll_idx; i++) {
  60                 if (kdb_poll_funcs[i] == kdb_get_kbd_char) {
  61                         kdb_poll_idx--;
  62                         kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx];
  63                         kdb_poll_funcs[kdb_poll_idx] = NULL;
  64                         i--;
  65                 }
  66         }
  67 }
  68 #else /* ! CONFIG_KDB_KEYBOARD */
  69 #define kgdboc_register_kbd(x) 0
  70 #define kgdboc_unregister_kbd()
  71 #endif /* ! CONFIG_KDB_KEYBOARD */
  72
  73 static int kgdboc_option_setup(char *opt)
  74 {
  75         if (strlen(opt) > MAX_CONFIG_LEN) {
  76                 printk(KERN_ERR "kgdboc: config string too long\n");
  77                 return -ENOSPC;
  78         }
  79         strcpy(config, opt);
  80
  81         return 0;
  82 }
  83
  84 __setup("kgdboc=", kgdboc_option_setup);
  85
  86 static void cleanup_kgdboc(void)
  87 {
  88         kgdboc_unregister_kbd();
  89         if (configured == 1)
  90                 kgdb_unregister_io_module(&kgdboc_io_ops);
  91 }
  92
  93 static int configure_kgdboc(void)
  94 {
  95         struct tty_driver *p;
  96         int tty_line = 0;
  97         int err;
  98         char *cptr = config;
  99         struct console *cons;
 100
 101         err = kgdboc_option_setup(config);
 102         if (err || !strlen(config) || isspace(config[0]))
 103                 goto noconfig;
 104
 105         err = -ENODEV;
 106         kgdboc_io_ops.is_console = 0;
 107         kgdb_tty_driver = NULL;
 108
 109         kgdboc_use_kms = 0;
 110         if (strncmp(cptr, "kms,", 4) == 0) {
 111                 cptr += 4;
 112                 kgdboc_use_kms = 1;
 113         }
 114
 115         if (kgdboc_register_kbd(&cptr))
 116                 goto do_register;
 117
 118         p = tty_find_polling_driver(cptr, &tty_line);
 119         if (!p)
 120                 goto noconfig;
 121
 122         cons = console_drivers;
 123         while (cons) {
 124                 int idx;
 125                 if (cons->device && cons->device(cons, &idx) == p &&
 126                     idx == tty_line) {
 127                         kgdboc_io_ops.is_console = 1;
 128                         break;
 129                 }
 130                 cons = cons->next;
 131         }
 132
 133         kgdb_tty_driver = p;
 134         kgdb_tty_line = tty_line;
 135
 136 do_register:
 137         err = kgdb_register_io_module(&kgdboc_io_ops);
 138         if (err)
 139                 goto noconfig;
 140
 141         configured = 1;
 142
 143         return 0;
 144
 145 noconfig:
 146         config[0] = 0;
 147         configured = 0;
 148         cleanup_kgdboc();
 149
 150         return err;
 151 }
 152
 153 static int __init init_kgdboc(void)
 154 {
 155         /* Already configured? */
 156         if (configured == 1)
 157                 return 0;
 158
 159         return configure_kgdboc();
 160 }
 161
 162 static int kgdboc_get_char(void)
 163 {
 164         if (!kgdb_tty_driver)
 165                 return -1;
 166         return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver,
 167                                                 kgdb_tty_line);
 168 }
 169
 170 static void kgdboc_put_char(u8 chr)
 171 {
 172         if (!kgdb_tty_driver)
 173                 return;
 174         kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver,
 175                                         kgdb_tty_line, chr);
 176 }
 177
 178 static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)
 179 {
 180         int len = strlen(kmessage);
 181
 182         if (len >= MAX_CONFIG_LEN) {
 183                 printk(KERN_ERR "kgdboc: config string too long\n");
 184                 return -ENOSPC;
 185         }
 186
 187         /* Only copy in the string if the init function has not run yet */
 188         if (configured < 0) {
 189                 strcpy(config, kmessage);
 190                 return 0;
 191         }
 192
 193         if (kgdb_connected) {
 194                 printk(KERN_ERR
 195                        "kgdboc: Cannot reconfigure while KGDB is connected.\n");
 196
 197                 return -EBUSY;
 198         }
 199
 200         strcpy(config, kmessage);
 201         /* Chop out \n char as a result of echo */
 202         if (config[len - 1] == '\n')
 203                 config[len - 1] = '\0';
 204
 205         if (configured == 1)
 206                 cleanup_kgdboc();
 207
 208         /* Go and configure with the new params. */
 209         return configure_kgdboc();
 210 }
 211
 212 static int dbg_restore_graphics;
 213
 214 static void kgdboc_pre_exp_handler(void)
 215 {
 216         if (!dbg_restore_graphics && kgdboc_use_kms) {
 217                 dbg_restore_graphics = 1;
 218                 con_debug_enter(vc_cons[fg_console].d);
 219         }
 220         /* Increment the module count when the debugger is active */
 221         if (!kgdb_connected)
 222                 try_module_get(THIS_MODULE);
 223 }
 224
 225 static void kgdboc_post_exp_handler(void)
 226 {
 227         /* decrement the module count when the debugger detaches */
 228         if (!kgdb_connected)
 229                 module_put(THIS_MODULE);
 230         if (kgdboc_use_kms && dbg_restore_graphics) {
 231                 dbg_restore_graphics = 0;
 232                 con_debug_leave();
 233         }
 234 }
 235
 236 static struct kgdb_io kgdboc_io_ops = {
 237         .name                   = "kgdboc",
 238         .read_char              = kgdboc_get_char,
 239         .write_char             = kgdboc_put_char,
 240         .pre_exception          = kgdboc_pre_exp_handler,
 241         .post_exception         = kgdboc_post_exp_handler,
 242 };
 243
 244 #ifdef CONFIG_KGDB_SERIAL_CONSOLE
 245 /* This is only available if kgdboc is a built in for early debugging */
 246 static int __init kgdboc_early_init(char *opt)
 247 {
 248         /* save the first character of the config string because the
 249          * init routine can destroy it.
 250          */
 251         char save_ch;
 252
 253         kgdboc_option_setup(opt);
 254         save_ch = config[0];
 255         init_kgdboc();
 256         config[0] = save_ch;
 257         return 0;
 258 }
 259
 260 early_param("ekgdboc", kgdboc_early_init);
 261 #endif /* CONFIG_KGDB_SERIAL_CONSOLE */
 262
 263 module_init(init_kgdboc);
 264 module_exit(cleanup_kgdboc);
 265 module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
 266 MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
 267 MODULE_DESCRIPTION("KGDB Console TTY Driver");
 268 MODULE_LICENSE("GPL");