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"); 340