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