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