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