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 if (kgdb_unregister_nmi_console()) 149 return; 150 kgdboc_unregister_kbd(); 151 if (configured == 1) 152 kgdb_unregister_io_module(&kgdboc_io_ops); 153 } 154 155 static int configure_kgdboc(void) 156 { 157 struct tty_driver *p; 158 int tty_line = 0; 159 int err; 160 char *cptr = config; 161 struct console *cons; 162 163 err = kgdboc_option_setup(config); 164 if (err || !strlen(config) || isspace(config[0])) 165 goto noconfig; 166 167 err = -ENODEV; 168 kgdboc_io_ops.is_console = 0; 169 kgdb_tty_driver = NULL; 170 171 kgdboc_use_kms = 0; 172 if (strncmp(cptr, "kms,", 4) == 0) { 173 cptr += 4; 174 kgdboc_use_kms = 1; 175 } 176 177 if (kgdboc_register_kbd(&cptr)) 178 goto do_register; 179 180 p = tty_find_polling_driver(cptr, &tty_line); 181 if (!p) 182 goto noconfig; 183 184 cons = console_drivers; 185 while (cons) { 186 int idx; 187 if (cons->device && cons->device(cons, &idx) == p && 188 idx == tty_line) { 189 kgdboc_io_ops.is_console = 1; 190 break; 191 } 192 cons = cons->next; 193 } 194 195 kgdb_tty_driver = p; 196 kgdb_tty_line = tty_line; 197 198 do_register: 199 err = kgdb_register_io_module(&kgdboc_io_ops); 200 if (err) 201 goto noconfig; 202 203 err = kgdb_register_nmi_console(); 204 if (err) 205 goto nmi_con_failed; 206 207 configured = 1; 208 209 return 0; 210 211 nmi_con_failed: 212 kgdb_unregister_io_module(&kgdboc_io_ops); 213 noconfig: 214 kgdboc_unregister_kbd(); 215 config[0] = 0; 216 configured = 0; 217 cleanup_kgdboc(); 218 219 return err; 220 } 221 222 static int __init init_kgdboc(void) 223 { 224 /* Already configured? */ 225 if (configured == 1) 226 return 0; 227 228 return configure_kgdboc(); 229 } 230 231 static int kgdboc_get_char(void) 232 { 233 if (!kgdb_tty_driver) 234 return -1; 235 return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver, 236 kgdb_tty_line); 237 } 238 239 static void kgdboc_put_char(u8 chr) 240 { 241 if (!kgdb_tty_driver) 242 return; 243 kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver, 244 kgdb_tty_line, chr); 245 } 246 247 static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp) 248 { 249 int len = strlen(kmessage); 250 251 if (len >= MAX_CONFIG_LEN) { 252 printk(KERN_ERR "kgdboc: config string too long\n"); 253 return -ENOSPC; 254 } 255 256 /* Only copy in the string if the init function has not run yet */ 257 if (configured < 0) { 258 strcpy(config, kmessage); 259 return 0; 260 } 261 262 if (kgdb_connected) { 263 printk(KERN_ERR 264 "kgdboc: Cannot reconfigure while KGDB is connected.\n"); 265 266 return -EBUSY; 267 } 268 269 strcpy(config, kmessage); 270 /* Chop out \n char as a result of echo */ 271 if (config[len - 1] == '\n') 272 config[len - 1] = '\0'; 273 274 if (configured == 1) 275 cleanup_kgdboc(); 276 277 /* Go and configure with the new params. */ 278 return configure_kgdboc(); 279 } 280 281 static int dbg_restore_graphics; 282 283 static void kgdboc_pre_exp_handler(void) 284 { 285 if (!dbg_restore_graphics && kgdboc_use_kms) { 286 dbg_restore_graphics = 1; 287 con_debug_enter(vc_cons[fg_console].d); 288 } 289 /* Increment the module count when the debugger is active */ 290 if (!kgdb_connected) 291 try_module_get(THIS_MODULE); 292 } 293 294 static void kgdboc_post_exp_handler(void) 295 { 296 /* decrement the module count when the debugger detaches */ 297 if (!kgdb_connected) 298 module_put(THIS_MODULE); 299 if (kgdboc_use_kms && dbg_restore_graphics) { 300 dbg_restore_graphics = 0; 301 con_debug_leave(); 302 } 303 kgdboc_restore_input(); 304 } 305 306 static struct kgdb_io kgdboc_io_ops = { 307 .name = "kgdboc", 308 .read_char = kgdboc_get_char, 309 .write_char = kgdboc_put_char, 310 .pre_exception = kgdboc_pre_exp_handler, 311 .post_exception = kgdboc_post_exp_handler, 312 }; 313 314 #ifdef CONFIG_KGDB_SERIAL_CONSOLE 315 /* This is only available if kgdboc is a built in for early debugging */ 316 static int __init kgdboc_early_init(char *opt) 317 { 318 /* save the first character of the config string because the 319 * init routine can destroy it. 320 */ 321 char save_ch; 322 323 kgdboc_option_setup(opt); 324 save_ch = config[0]; 325 init_kgdboc(); 326 config[0] = save_ch; 327 return 0; 328 } 329 330 early_param("ekgdboc", kgdboc_early_init); 331 #endif /* CONFIG_KGDB_SERIAL_CONSOLE */ 332 333 module_init(init_kgdboc); 334 module_exit(cleanup_kgdboc); 335 module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644); 336 MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]"); 337 MODULE_DESCRIPTION("KGDB Console TTY Driver"); 338 MODULE_LICENSE("GPL"); 339