Pileus Git - ~andy/linux/blob - arch/alpha/kernel/srmcons.c

   1 /*
   2  *      linux/arch/alpha/kernel/srmcons.c
   3  *
   4  * Callback based driver for SRM Console console device.
   5  * (TTY driver and console driver)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/init.h>
  10 #include <linux/console.h>
  11 #include <linux/delay.h>
  12 #include <linux/mm.h>
  13 #include <linux/slab.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/timer.h>
  16 #include <linux/tty.h>
  17 #include <linux/tty_driver.h>
  18 #include <linux/tty_flip.h>
  19
  20 #include <asm/console.h>
  21 #include <asm/uaccess.h>
  22
  23
  24 static DEFINE_SPINLOCK(srmcons_callback_lock);
  25 static int srm_is_registered_console = 0;
  26
  27 /*
  28  * The TTY driver
  29  */
  30 #define MAX_SRM_CONSOLE_DEVICES 1       /* only support 1 console device */
  31
  32 struct srmcons_private {
  33         struct tty_struct *tty;
  34         struct timer_list timer;
  35         spinlock_t lock;
  36 };
  37
  38 typedef union _srmcons_result {
  39         struct {
  40                 unsigned long c :61;
  41                 unsigned long status :3;
  42         } bits;
  43         long as_long;
  44 } srmcons_result;
  45
  46 /* called with callback_lock held */
  47 static int
  48 srmcons_do_receive_chars(struct tty_struct *tty)
  49 {
  50         srmcons_result result;
  51         int count = 0, loops = 0;
  52
  53         do {
  54                 result.as_long = callback_getc(0);
  55                 if (result.bits.status < 2) {
  56                         tty_insert_flip_char(tty, (char)result.bits.c, 0);
  57                         count++;
  58                 }
  59         } while((result.bits.status & 1) && (++loops < 10));
  60
  61         if (count)
  62                 tty_schedule_flip(tty);
  63
  64         return count;
  65 }
  66
  67 static void
  68 srmcons_receive_chars(unsigned long data)
  69 {
  70         struct srmcons_private *srmconsp = (struct srmcons_private *)data;
  71         unsigned long flags;
  72         int incr = 10;
  73
  74         local_irq_save(flags);
  75         if (spin_trylock(&srmcons_callback_lock)) {
  76                 if (!srmcons_do_receive_chars(srmconsp->tty))
  77                         incr = 100;
  78                 spin_unlock(&srmcons_callback_lock);
  79         }
  80
  81         spin_lock(&srmconsp->lock);
  82         if (srmconsp->tty)
  83                 mod_timer(&srmconsp->timer, jiffies + incr);
  84         spin_unlock(&srmconsp->lock);
  85
  86         local_irq_restore(flags);
  87 }
  88
  89 /* called with callback_lock held */
  90 static int
  91 srmcons_do_write(struct tty_struct *tty, const char *buf, int count)
  92 {
  93         static char str_cr[1] = "\r";
  94         long c, remaining = count;
  95         srmcons_result result;
  96         char *cur;
  97         int need_cr;
  98
  99         for (cur = (char *)buf; remaining > 0; ) {
 100                 need_cr = 0;
 101                 /*
 102                  * Break it up into reasonable size chunks to allow a chance
 103                  * for input to get in
 104                  */
 105                 for (c = 0; c < min_t(long, 128L, remaining) && !need_cr; c++)
 106                         if (cur[c] == '\n')
 107                                 need_cr = 1;
 108
 109                 while (c > 0) {
 110                         result.as_long = callback_puts(0, cur, c);
 111                         c -= result.bits.c;
 112                         remaining -= result.bits.c;
 113                         cur += result.bits.c;
 114
 115                         /*
 116                          * Check for pending input iff a tty was provided
 117                          */
 118                         if (tty)
 119                                 srmcons_do_receive_chars(tty);
 120                 }
 121
 122                 while (need_cr) {
 123                         result.as_long = callback_puts(0, str_cr, 1);
 124                         if (result.bits.c > 0)
 125                                 need_cr = 0;
 126                 }
 127         }
 128         return count;
 129 }
 130
 131 static int
 132 srmcons_write(struct tty_struct *tty,
 133               const unsigned char *buf, int count)
 134 {
 135         unsigned long flags;
 136
 137         spin_lock_irqsave(&srmcons_callback_lock, flags);
 138         srmcons_do_write(tty, (const char *) buf, count);
 139         spin_unlock_irqrestore(&srmcons_callback_lock, flags);
 140
 141         return count;
 142 }
 143
 144 static int
 145 srmcons_write_room(struct tty_struct *tty)
 146 {
 147         return 512;
 148 }
 149
 150 static int
 151 srmcons_chars_in_buffer(struct tty_struct *tty)
 152 {
 153         return 0;
 154 }
 155
 156 static int
 157 srmcons_get_private_struct(struct srmcons_private **ps)
 158 {
 159         static struct srmcons_private *srmconsp = NULL;
 160         static DEFINE_SPINLOCK(srmconsp_lock);
 161         unsigned long flags;
 162         int retval = 0;
 163
 164         if (srmconsp == NULL) {
 165                 srmconsp = kmalloc(sizeof(*srmconsp), GFP_KERNEL);
 166                 spin_lock_irqsave(&srmconsp_lock, flags);
 167
 168                 if (srmconsp == NULL)
 169                         retval = -ENOMEM;
 170                 else {
 171                         srmconsp->tty = NULL;
 172                         spin_lock_init(&srmconsp->lock);
 173                         setup_timer(&srmconsp->timer, srmcons_receive_chars,
 174                                         (unsigned long)srmconsp);
 175                 }
 176
 177                 spin_unlock_irqrestore(&srmconsp_lock, flags);
 178         }
 179
 180         *ps = srmconsp;
 181         return retval;
 182 }
 183
 184 static int
 185 srmcons_open(struct tty_struct *tty, struct file *filp)
 186 {
 187         struct srmcons_private *srmconsp;
 188         unsigned long flags;
 189         int retval;
 190
 191         retval = srmcons_get_private_struct(&srmconsp);
 192         if (retval)
 193                 return retval;
 194
 195         spin_lock_irqsave(&srmconsp->lock, flags);
 196
 197         if (!srmconsp->tty) {
 198                 tty->driver_data = srmconsp;
 199
 200                 srmconsp->tty = tty;
 201                 mod_timer(&srmconsp->timer, jiffies + 10);
 202         }
 203
 204         spin_unlock_irqrestore(&srmconsp->lock, flags);
 205
 206         return 0;
 207 }
 208
 209 static void
 210 srmcons_close(struct tty_struct *tty, struct file *filp)
 211 {
 212         struct srmcons_private *srmconsp = tty->driver_data;
 213         unsigned long flags;
 214
 215         spin_lock_irqsave(&srmconsp->lock, flags);
 216
 217         if (tty->count == 1) {
 218                 srmconsp->tty = NULL;
 219                 del_timer(&srmconsp->timer);
 220         }
 221
 222         spin_unlock_irqrestore(&srmconsp->lock, flags);
 223 }
 224
 225
 226 static struct tty_driver *srmcons_driver;
 227
 228 static const struct tty_operations srmcons_ops = {
 229         .open           = srmcons_open,
 230         .close          = srmcons_close,
 231         .write          = srmcons_write,
 232         .write_room     = srmcons_write_room,
 233         .chars_in_buffer= srmcons_chars_in_buffer,
 234 };
 235
 236 static int __init
 237 srmcons_init(void)
 238 {
 239         if (srm_is_registered_console) {
 240                 struct tty_driver *driver;
 241                 int err;
 242
 243                 driver = alloc_tty_driver(MAX_SRM_CONSOLE_DEVICES);
 244                 if (!driver)
 245                         return -ENOMEM;
 246                 driver->driver_name = "srm";
 247                 driver->name = "srm";
 248                 driver->major = 0;      /* dynamic */
 249                 driver->minor_start = 0;
 250                 driver->type = TTY_DRIVER_TYPE_SYSTEM;
 251                 driver->subtype = SYSTEM_TYPE_SYSCONS;
 252                 driver->init_termios = tty_std_termios;
 253                 tty_set_operations(driver, &srmcons_ops);
 254                 err = tty_register_driver(driver);
 255                 if (err) {
 256                         put_tty_driver(driver);
 257                         return err;
 258                 }
 259                 srmcons_driver = driver;
 260         }
 261
 262         return -ENODEV;
 263 }
 264
 265 module_init(srmcons_init);
 266
 267 \f
 268 /*
 269  * The console driver
 270  */
 271 static void
 272 srm_console_write(struct console *co, const char *s, unsigned count)
 273 {
 274         unsigned long flags;
 275
 276         spin_lock_irqsave(&srmcons_callback_lock, flags);
 277         srmcons_do_write(NULL, s, count);
 278         spin_unlock_irqrestore(&srmcons_callback_lock, flags);
 279 }
 280
 281 static struct tty_driver *
 282 srm_console_device(struct console *co, int *index)
 283 {
 284         *index = co->index;
 285         return srmcons_driver;
 286 }
 287
 288 static int
 289 srm_console_setup(struct console *co, char *options)
 290 {
 291         return 0;
 292 }
 293
 294 static struct console srmcons = {
 295         .name           = "srm",
 296         .write          = srm_console_write,
 297         .device         = srm_console_device,
 298         .setup          = srm_console_setup,
 299         .flags          = CON_PRINTBUFFER | CON_BOOT,
 300         .index          = -1,
 301 };
 302
 303 void __init
 304 register_srm_console(void)
 305 {
 306         if (!srm_is_registered_console) {
 307                 callback_open_console();
 308                 register_console(&srmcons);
 309                 srm_is_registered_console = 1;
 310         }
 311 }
 312
 313 void __init
 314 unregister_srm_console(void)
 315 {
 316         if (srm_is_registered_console) {
 317                 callback_close_console();
 318                 unregister_console(&srmcons);
 319                 srm_is_registered_console = 0;
 320         }
 321 }