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 if (likely(system_state == SYSTEM_RUNNING)) 94 schedule_work(&kgdboc_restore_input_work); 95 } 96 97 static int kgdboc_register_kbd(char **cptr) 98 { 99 if (strncmp(*cptr, "kbd", 3) == 0) { 100 if (kdb_poll_idx < KDB_POLL_FUNC_MAX) { 101 kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char; 102 kdb_poll_idx++; 103 if (cptr[0][3] == ',') 104 *cptr += 4; 105 else 106 return 1; 107 } 108 } 109 return 0; 110 } 111 112 static void kgdboc_unregister_kbd(void) 113 { 114 int i; 115 116 for (i = 0; i < kdb_poll_idx; i++) { 117 if (kdb_poll_funcs[i] == kdb_get_kbd_char) { 118 kdb_poll_idx--; 119 kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx]; 120 kdb_poll_funcs[kdb_poll_idx] = NULL; 121 i--; 122 } 123 } 124 flush_work_sync(&kgdboc_restore_input_work); 125 } 126 #else /* ! CONFIG_KDB_KEYBOARD */ 127 #define kgdboc_register_kbd(x) 0 128 #define kgdboc_unregister_kbd() 129 #define kgdboc_restore_input() 130 #endif /* ! CONFIG_KDB_KEYBOARD */ 131 132 static int kgdboc_option_setup(char *opt) 133 { 134 if (strlen(opt) > MAX_CONFIG_LEN) { 135 printk(KERN_ERR "kgdboc: config string too long\n"); 136 return -ENOSPC; 137 } 138 strcpy(config, opt); 139 140 return 0; 141 } 142 143 __setup("kgdboc=", kgdboc_option_setup); 144 145 static void cleanup_kgdboc(void) 146 { 147 kgdboc_unregister_kbd(); 148 if (configured == 1) 149 kgdb_unregister_io_module(&kgdboc_io_ops); 150 } 151 152 static int configure_kgdboc(void) 153 { 154 struct tty_driver *p; 155 int tty_line = 0; 156 int err; 157 char *cptr = config; 158 struct console *cons; 159 160 err = kgdboc_option_setup(config); 161 if (err || !strlen(config) || isspace(config[0])) 162 goto noconfig; 163 164 err = -ENODEV; 165 kgdboc_io_ops.is_console = 0; 166 kgdb_tty_driver = NULL; 167 168 kgdboc_use_kms = 0; 169 if (strncmp(cptr, "kms,", 4) == 0) { 170 cptr += 4; 171 kgdboc_use_kms = 1; 172 } 173 174 if (kgdboc_register_kbd(&cptr)) 175 goto do_register; 176 177 p = tty_find_polling_driver(cptr, &tty_line); 178 if (!p) 179 goto noconfig; 180 181 cons = console_drivers; 182 while (cons) { 183 int idx; 184 if (cons->device && cons->device(cons, &idx) == p && 185 idx == tty_line) { 186 kgdboc_io_ops.is_console = 1; 187 break; 188 } 189 cons = cons->next; 190 } 191 192 kgdb_tty_driver = p; 193 kgdb_tty_line = tty_line; 194 195 do_register: 196 err = kgdb_register_io_module(&kgdboc_io_ops); 197 if (err) 198 goto noconfig; 199 200 configured = 1; 201 202 return 0; 203 204 noconfig: 205 config[0] = 0; 206 configured = 0; 207 cleanup_kgdboc(); 208 209 return err; 210 } 211 212 static int __init init_kgdboc(void) 213 { 214 /* Already configured? */ 215 if (configured == 1) 216 return 0; 217 218 return configure_kgdboc(); 219 } 220 221 static int kgdboc_get_char(void) 222 { 223 if (!kgdb_tty_driver) 224 return -1; 225 return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver, 226 kgdb_tty_line); 227 } 228 229 static void kgdboc_put_char(u8 chr) 230 { 231 if (!kgdb_tty_driver) 232 return; 233 kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver, 234 kgdb_tty_line, chr); 235 } 236 237 static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp) 238 { 239 int len = strlen(kmessage); 240 241 if (len >= MAX_CONFIG_LEN) { 242 printk(KERN_ERR "kgdboc: config string too long\n"); 243 return -ENOSPC; 244 } 245 246 /* Only copy in the string if the init function has not run yet */ 247 if (configured < 0) { 248 strcpy(config, kmessage); 249 return 0; 250 } 251 252 if (kgdb_connected) { 253 printk(KERN_ERR 254 "kgdboc: Cannot reconfigure while KGDB is connected.\n"); 255 256 return -EBUSY; 257 } 258 259 strcpy(config, kmessage); 260 /* Chop out \n char as a result of echo */ 261 if (config[len - 1] == '\n') 262 config[len - 1] = '\0'; 263 264 if (configured == 1) 265 cleanup_kgdboc(); 266 267 /* Go and configure with the new params. */ 268 return configure_kgdboc(); 269 } 270 271 static int dbg_restore_graphics; 272 273 static void kgdboc_pre_exp_handler(void) 274 { 275 if (!dbg_restore_graphics && kgdboc_use_kms) { 276 dbg_restore_graphics = 1; 277 con_debug_enter(vc_cons[fg_console].d); 278 } 279 /* Increment the module count when the debugger is active */ 280 if (!kgdb_connected) 281 try_module_get(THIS_MODULE); 282 } 283 284 static void kgdboc_post_exp_handler(void) 285 { 286 /* decrement the module count when the debugger detaches */ 287 if (!kgdb_connected) 288 module_put(THIS_MODULE); 289 if (kgdboc_use_kms && dbg_restore_graphics) { 290 dbg_restore_graphics = 0; 291 con_debug_leave(); 292 } 293 kgdboc_restore_input(); 294 } 295 296 static struct kgdb_io kgdboc_io_ops = { 297 .name = "kgdboc", 298 .read_char = kgdboc_get_char, 299 .write_char = kgdboc_put_char, 300 .pre_exception = kgdboc_pre_exp_handler, 301 .post_exception = kgdboc_post_exp_handler, 302 }; 303 304 #ifdef CONFIG_KGDB_SERIAL_CONSOLE 305 /* This is only available if kgdboc is a built in for early debugging */ 306 static int __init kgdboc_early_init(char *opt) 307 { 308 /* save the first character of the config string because the 309 * init routine can destroy it. 310 */ 311 char save_ch; 312 313 kgdboc_option_setup(opt); 314 save_ch = config[0]; 315 init_kgdboc(); 316 config[0] = save_ch; 317 return 0; 318 } 319 320 early_param("ekgdboc", kgdboc_early_init); 321 #endif /* CONFIG_KGDB_SERIAL_CONSOLE */ 322 323 module_init(init_kgdboc); 324 module_exit(cleanup_kgdboc); 325 module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644); 326 MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]"); 327 MODULE_DESCRIPTION("KGDB Console TTY Driver"); 328 MODULE_LICENSE("GPL"); 329