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                 srmconsp->timer.expires = jiffies + incr;
  84                 add_timer(&srmconsp->timer);
  85         }
  86         spin_unlock(&srmconsp->lock);
  87
  88         local_irq_restore(flags);
  89 }
  90
  91 /* called with callback_lock held */
  92 static int
  93 srmcons_do_write(struct tty_struct *tty, const char *buf, int count)
  94 {
  95         static char str_cr[1] = "\r";
  96         long c, remaining = count;
  97         srmcons_result result;
  98         char *cur;
  99         int need_cr;
 100
 101         for (cur = (char *)buf; remaining > 0; ) {
 102                 need_cr = 0;
 103                 /*
 104                  * Break it up into reasonable size chunks to allow a chance
 105                  * for input to get in
 106                  */
 107                 for (c = 0; c < min_t(long, 128L, remaining) && !need_cr; c++)
 108                         if (cur[c] == '\n')
 109                                 need_cr = 1;
 110
 111                 while (c > 0) {
 112                         result.as_long = callback_puts(0, cur, c);
 113                         c -= result.bits.c;
 114                         remaining -= result.bits.c;
 115                         cur += result.bits.c;
 116
 117                         /*
 118                          * Check for pending input iff a tty was provided
 119                          */
 120                         if (tty)
 121                                 srmcons_do_receive_chars(tty);
 122                 }
 123
 124                 while (need_cr) {
 125                         result.as_long = callback_puts(0, str_cr, 1);
 126                         if (result.bits.c > 0)
 127                                 need_cr = 0;
 128                 }
 129         }
 130         return count;
 131 }
 132
 133 static int
 134 srmcons_write(struct tty_struct *tty,
 135               const unsigned char *buf, int count)
 136 {
 137         unsigned long flags;
 138
 139         spin_lock_irqsave(&srmcons_callback_lock, flags);
 140         srmcons_do_write(tty, (const char *) buf, count);
 141         spin_unlock_irqrestore(&srmcons_callback_lock, flags);
 142
 143         return count;
 144 }
 145
 146 static int
 147 srmcons_write_room(struct tty_struct *tty)
 148 {
 149         return 512;
 150 }
 151
 152 static int
 153 srmcons_chars_in_buffer(struct tty_struct *tty)
 154 {
 155         return 0;
 156 }
 157
 158 static int
 159 srmcons_get_private_struct(struct srmcons_private **ps)
 160 {
 161         static struct srmcons_private *srmconsp = NULL;
 162         static DEFINE_SPINLOCK(srmconsp_lock);
 163         unsigned long flags;
 164         int retval = 0;
 165
 166         if (srmconsp == NULL) {
 167                 srmconsp = kmalloc(sizeof(*srmconsp), GFP_KERNEL);
 168                 spin_lock_irqsave(&srmconsp_lock, flags);
 169
 170                 if (srmconsp == NULL)
 171                         retval = -ENOMEM;
 172                 else {
 173                         srmconsp->tty = NULL;
 174                         spin_lock_init(&srmconsp->lock);
 175                         init_timer(&srmconsp->timer);
 176                 }
 177
 178                 spin_unlock_irqrestore(&srmconsp_lock, flags);
 179         }
 180
 181         *ps = srmconsp;
 182         return retval;
 183 }
 184
 185 static int
 186 srmcons_open(struct tty_struct *tty, struct file *filp)
 187 {
 188         struct srmcons_private *srmconsp;
 189         unsigned long flags;
 190         int retval;
 191
 192         retval = srmcons_get_private_struct(&srmconsp);
 193         if (retval)
 194                 return retval;
 195
 196         spin_lock_irqsave(&srmconsp->lock, flags);
 197
 198         if (!srmconsp->tty) {
 199                 tty->driver_data = srmconsp;
 200
 201                 srmconsp->tty = tty;
 202                 srmconsp->timer.function = srmcons_receive_chars;
 203                 srmconsp->timer.data = (unsigned long)srmconsp;
 204                 srmconsp->timer.expires = jiffies + 10;
 205                 add_timer(&srmconsp->timer);
 206         }
 207
 208         spin_unlock_irqrestore(&srmconsp->lock, flags);
 209
 210         return 0;
 211 }
 212
 213 static void
 214 srmcons_close(struct tty_struct *tty, struct file *filp)
 215 {
 216         struct srmcons_private *srmconsp = tty->driver_data;
 217         unsigned long flags;
 218
 219         spin_lock_irqsave(&srmconsp->lock, flags);
 220
 221         if (tty->count == 1) {
 222                 srmconsp->tty = NULL;
 223                 del_timer(&srmconsp->timer);
 224         }
 225
 226         spin_unlock_irqrestore(&srmconsp->lock, flags);
 227 }
 228
 229
 230 static struct tty_driver *srmcons_driver;
 231
 232 static const struct tty_operations srmcons_ops = {
 233         .open           = srmcons_open,
 234         .close          = srmcons_close,
 235         .write          = srmcons_write,
 236         .write_room     = srmcons_write_room,
 237         .chars_in_buffer= srmcons_chars_in_buffer,
 238 };
 239
 240 static int __init
 241 srmcons_init(void)
 242 {
 243         if (srm_is_registered_console) {
 244                 struct tty_driver *driver;
 245                 int err;
 246
 247                 driver = alloc_tty_driver(MAX_SRM_CONSOLE_DEVICES);
 248                 if (!driver)
 249                         return -ENOMEM;
 250                 driver->driver_name = "srm";
 251                 driver->name = "srm";
 252                 driver->major = 0;      /* dynamic */
 253                 driver->minor_start = 0;
 254                 driver->type = TTY_DRIVER_TYPE_SYSTEM;
 255                 driver->subtype = SYSTEM_TYPE_SYSCONS;
 256                 driver->init_termios = tty_std_termios;
 257                 tty_set_operations(driver, &srmcons_ops);
 258                 err = tty_register_driver(driver);
 259                 if (err) {
 260                         put_tty_driver(driver);
 261                         return err;
 262                 }
 263                 srmcons_driver = driver;
 264         }
 265
 266         return -ENODEV;
 267 }
 268
 269 module_init(srmcons_init);
 270
 271 \f
 272 /*
 273  * The console driver
 274  */
 275 static void
 276 srm_console_write(struct console *co, const char *s, unsigned count)
 277 {
 278         unsigned long flags;
 279
 280         spin_lock_irqsave(&srmcons_callback_lock, flags);
 281         srmcons_do_write(NULL, s, count);
 282         spin_unlock_irqrestore(&srmcons_callback_lock, flags);
 283 }
 284
 285 static struct tty_driver *
 286 srm_console_device(struct console *co, int *index)
 287 {
 288         *index = co->index;
 289         return srmcons_driver;
 290 }
 291
 292 static int
 293 srm_console_setup(struct console *co, char *options)
 294 {
 295         return 0;
 296 }
 297
 298 static struct console srmcons = {
 299         .name           = "srm",
 300         .write          = srm_console_write,
 301         .device         = srm_console_device,
 302         .setup          = srm_console_setup,
 303         .flags          = CON_PRINTBUFFER | CON_BOOT,
 304         .index          = -1,
 305 };
 306
 307 void __init
 308 register_srm_console(void)
 309 {
 310         if (!srm_is_registered_console) {
 311                 callback_open_console();
 312                 register_console(&srmcons);
 313                 srm_is_registered_console = 1;
 314         }
 315 }
 316
 317 void __init
 318 unregister_srm_console(void)
 319 {
 320         if (srm_is_registered_console) {
 321                 callback_close_console();
 322                 unregister_console(&srmcons);
 323                 srm_is_registered_console = 0;
 324         }
 325 }