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_port port;
  34         struct timer_list timer;
  35 } srmcons_singleton;
  36
  37 typedef union _srmcons_result {
  38         struct {
  39                 unsigned long c :61;
  40                 unsigned long status :3;
  41         } bits;
  42         long as_long;
  43 } srmcons_result;
  44
  45 /* called with callback_lock held */
  46 static int
  47 srmcons_do_receive_chars(struct tty_port *port)
  48 {
  49         srmcons_result result;
  50         int count = 0, loops = 0;
  51
  52         do {
  53                 result.as_long = callback_getc(0);
  54                 if (result.bits.status < 2) {
  55                         tty_insert_flip_char(port, (char)result.bits.c, 0);
  56                         count++;
  57                 }
  58         } while((result.bits.status & 1) && (++loops < 10));
  59
  60         if (count)
  61                 tty_schedule_flip(port);
  62
  63         return count;
  64 }
  65
  66 static void
  67 srmcons_receive_chars(unsigned long data)
  68 {
  69         struct srmcons_private *srmconsp = (struct srmcons_private *)data;
  70         struct tty_port *port = &srmconsp->port;
  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(port))
  77                         incr = 100;
  78                 spin_unlock(&srmcons_callback_lock);
  79         }
  80
  81         spin_lock(&port->lock);
  82         if (port->tty)
  83                 mod_timer(&srmconsp->timer, jiffies + incr);
  84         spin_unlock(&port->lock);
  85
  86         local_irq_restore(flags);
  87 }
  88
  89 /* called with callback_lock held */
  90 static int
  91 srmcons_do_write(struct tty_port *port, 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 port was provided
 117                          */
 118                         if (port)
 119                                 srmcons_do_receive_chars(port);
 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->port, (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_open(struct tty_struct *tty, struct file *filp)
 158 {
 159         struct srmcons_private *srmconsp = &srmcons_singleton;
 160         struct tty_port *port = &srmconsp->port;
 161         unsigned long flags;
 162
 163         spin_lock_irqsave(&port->lock, flags);
 164
 165         if (!port->tty) {
 166                 tty->driver_data = srmconsp;
 167                 tty->port = port;
 168                 port->tty = tty; /* XXX proper refcounting */
 169                 mod_timer(&srmconsp->timer, jiffies + 10);
 170         }
 171
 172         spin_unlock_irqrestore(&port->lock, flags);
 173
 174         return 0;
 175 }
 176
 177 static void
 178 srmcons_close(struct tty_struct *tty, struct file *filp)
 179 {
 180         struct srmcons_private *srmconsp = tty->driver_data;
 181         struct tty_port *port = &srmconsp->port;
 182         unsigned long flags;
 183
 184         spin_lock_irqsave(&port->lock, flags);
 185
 186         if (tty->count == 1) {
 187                 port->tty = NULL;
 188                 del_timer(&srmconsp->timer);
 189         }
 190
 191         spin_unlock_irqrestore(&port->lock, flags);
 192 }
 193
 194
 195 static struct tty_driver *srmcons_driver;
 196
 197 static const struct tty_operations srmcons_ops = {
 198         .open           = srmcons_open,
 199         .close          = srmcons_close,
 200         .write          = srmcons_write,
 201         .write_room     = srmcons_write_room,
 202         .chars_in_buffer= srmcons_chars_in_buffer,
 203 };
 204
 205 static int __init
 206 srmcons_init(void)
 207 {
 208         setup_timer(&srmcons_singleton.timer, srmcons_receive_chars,
 209                         (unsigned long)&srmcons_singleton);
 210         if (srm_is_registered_console) {
 211                 struct tty_driver *driver;
 212                 int err;
 213
 214                 driver = alloc_tty_driver(MAX_SRM_CONSOLE_DEVICES);
 215                 if (!driver)
 216                         return -ENOMEM;
 217
 218                 tty_port_init(&srmcons_singleton.port);
 219
 220                 driver->driver_name = "srm";
 221                 driver->name = "srm";
 222                 driver->major = 0;      /* dynamic */
 223                 driver->minor_start = 0;
 224                 driver->type = TTY_DRIVER_TYPE_SYSTEM;
 225                 driver->subtype = SYSTEM_TYPE_SYSCONS;
 226                 driver->init_termios = tty_std_termios;
 227                 tty_set_operations(driver, &srmcons_ops);
 228                 tty_port_link_device(&srmcons_singleton.port, driver, 0);
 229                 err = tty_register_driver(driver);
 230                 if (err) {
 231                         put_tty_driver(driver);
 232                         tty_port_destroy(&srmcons_singleton.port);
 233                         return err;
 234                 }
 235                 srmcons_driver = driver;
 236         }
 237
 238         return -ENODEV;
 239 }
 240
 241 module_init(srmcons_init);
 242
 243 \f
 244 /*
 245  * The console driver
 246  */
 247 static void
 248 srm_console_write(struct console *co, const char *s, unsigned count)
 249 {
 250         unsigned long flags;
 251
 252         spin_lock_irqsave(&srmcons_callback_lock, flags);
 253         srmcons_do_write(NULL, s, count);
 254         spin_unlock_irqrestore(&srmcons_callback_lock, flags);
 255 }
 256
 257 static struct tty_driver *
 258 srm_console_device(struct console *co, int *index)
 259 {
 260         *index = co->index;
 261         return srmcons_driver;
 262 }
 263
 264 static int
 265 srm_console_setup(struct console *co, char *options)
 266 {
 267         return 0;
 268 }
 269
 270 static struct console srmcons = {
 271         .name           = "srm",
 272         .write          = srm_console_write,
 273         .device         = srm_console_device,
 274         .setup          = srm_console_setup,
 275         .flags          = CON_PRINTBUFFER | CON_BOOT,
 276         .index          = -1,
 277 };
 278
 279 void __init
 280 register_srm_console(void)
 281 {
 282         if (!srm_is_registered_console) {
 283                 callback_open_console();
 284                 register_console(&srmcons);
 285                 srm_is_registered_console = 1;
 286         }
 287 }
 288
 289 void __init
 290 unregister_srm_console(void)
 291 {
 292         if (srm_is_registered_console) {
 293                 callback_close_console();
 294                 unregister_console(&srmcons);
 295                 srm_is_registered_console = 0;
 296         }
 297 }