drivers/s390/char/sclp_con.c

   1 /*
   2  * SCLP line mode console driver
   3  *
   4  * Copyright IBM Corp. 1999, 2009
   5  * Author(s): Martin Peschke <mpeschke@de.ibm.com>
   6  *            Martin Schwidefsky <schwidefsky@de.ibm.com>
   7  */
   8
   9 #include <linux/kmod.h>
  10 #include <linux/console.h>
  11 #include <linux/init.h>
  12 #include <linux/timer.h>
  13 #include <linux/jiffies.h>
  14 #include <linux/termios.h>
  15 #include <linux/err.h>
  16 #include <linux/reboot.h>
  17 #include <linux/gfp.h>
  18
  19 #include "sclp.h"
  20 #include "sclp_rw.h"
  21 #include "sclp_tty.h"
  22
  23 #define sclp_console_major 4            /* TTYAUX_MAJOR */
  24 #define sclp_console_minor 64
  25 #define sclp_console_name  "ttyS"
  26
  27 /* Lock to guard over changes to global variables */
  28 static spinlock_t sclp_con_lock;
  29 /* List of free pages that can be used for console output buffering */
  30 static struct list_head sclp_con_pages;
  31 /* List of full struct sclp_buffer structures ready for output */
  32 static struct list_head sclp_con_outqueue;
  33 /* Pointer to current console buffer */
  34 static struct sclp_buffer *sclp_conbuf;
  35 /* Timer for delayed output of console messages */
  36 static struct timer_list sclp_con_timer;
  37 /* Suspend mode flag */
  38 static int sclp_con_suspended;
  39 /* Flag that output queue is currently running */
  40 static int sclp_con_queue_running;
  41
  42 /* Output format for console messages */
  43 static unsigned short sclp_con_columns;
  44 static unsigned short sclp_con_width_htab;
  45
  46 static void
  47 sclp_conbuf_callback(struct sclp_buffer *buffer, int rc)
  48 {
  49         unsigned long flags;
  50         void *page;
  51
  52         do {
  53                 page = sclp_unmake_buffer(buffer);
  54                 spin_lock_irqsave(&sclp_con_lock, flags);
  55
  56                 /* Remove buffer from outqueue */
  57                 list_del(&buffer->list);
  58                 list_add_tail((struct list_head *) page, &sclp_con_pages);
  59
  60                 /* Check if there is a pending buffer on the out queue. */
  61                 buffer = NULL;
  62                 if (!list_empty(&sclp_con_outqueue))
  63                         buffer = list_first_entry(&sclp_con_outqueue,
  64                                                   struct sclp_buffer, list);
  65                 if (!buffer || sclp_con_suspended) {
  66                         sclp_con_queue_running = 0;
  67                         spin_unlock_irqrestore(&sclp_con_lock, flags);
  68                         break;
  69                 }
  70                 spin_unlock_irqrestore(&sclp_con_lock, flags);
  71         } while (sclp_emit_buffer(buffer, sclp_conbuf_callback));
  72 }
  73
  74 /*
  75  * Finalize and emit first pending buffer.
  76  */
  77 static void sclp_conbuf_emit(void)
  78 {
  79         struct sclp_buffer* buffer;
  80         unsigned long flags;
  81         int rc;
  82
  83         spin_lock_irqsave(&sclp_con_lock, flags);
  84         if (sclp_conbuf)
  85                 list_add_tail(&sclp_conbuf->list, &sclp_con_outqueue);
  86         sclp_conbuf = NULL;
  87         if (sclp_con_queue_running || sclp_con_suspended)
  88                 goto out_unlock;
  89         if (list_empty(&sclp_con_outqueue))
  90                 goto out_unlock;
  91         buffer = list_first_entry(&sclp_con_outqueue, struct sclp_buffer,
  92                                   list);
  93         sclp_con_queue_running = 1;
  94         spin_unlock_irqrestore(&sclp_con_lock, flags);
  95
  96         rc = sclp_emit_buffer(buffer, sclp_conbuf_callback);
  97         if (rc)
  98                 sclp_conbuf_callback(buffer, rc);
  99         return;
 100 out_unlock:
 101         spin_unlock_irqrestore(&sclp_con_lock, flags);
 102 }
 103
 104 /*
 105  * Wait until out queue is empty
 106  */
 107 static void sclp_console_sync_queue(void)
 108 {
 109         unsigned long flags;
 110
 111         spin_lock_irqsave(&sclp_con_lock, flags);
 112         if (timer_pending(&sclp_con_timer))
 113                 del_timer(&sclp_con_timer);
 114         while (sclp_con_queue_running) {
 115                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 116                 sclp_sync_wait();
 117                 spin_lock_irqsave(&sclp_con_lock, flags);
 118         }
 119         spin_unlock_irqrestore(&sclp_con_lock, flags);
 120 }
 121
 122 /*
 123  * When this routine is called from the timer then we flush the
 124  * temporary write buffer without further waiting on a final new line.
 125  */
 126 static void
 127 sclp_console_timeout(unsigned long data)
 128 {
 129         sclp_conbuf_emit();
 130 }
 131
 132 /*
 133  * Drop oldest console buffer if sclp_con_drop is set
 134  */
 135 static int
 136 sclp_console_drop_buffer(void)
 137 {
 138         struct list_head *list;
 139         struct sclp_buffer *buffer;
 140         void *page;
 141
 142         if (!sclp_console_drop)
 143                 return 0;
 144         list = sclp_con_outqueue.next;
 145         if (sclp_con_queue_running)
 146                 /* The first element is in I/O */
 147                 list = list->next;
 148         if (list == &sclp_con_outqueue)
 149                 return 0;
 150         list_del(list);
 151         buffer = list_entry(list, struct sclp_buffer, list);
 152         page = sclp_unmake_buffer(buffer);
 153         list_add_tail((struct list_head *) page, &sclp_con_pages);
 154         return 1;
 155 }
 156
 157 /*
 158  * Writes the given message to S390 system console
 159  */
 160 static void
 161 sclp_console_write(struct console *console, const char *message,
 162                    unsigned int count)
 163 {
 164         unsigned long flags;
 165         void *page;
 166         int written;
 167
 168         if (count == 0)
 169                 return;
 170         spin_lock_irqsave(&sclp_con_lock, flags);
 171         /*
 172          * process escape characters, write message into buffer,
 173          * send buffer to SCLP
 174          */
 175         do {
 176                 /* make sure we have a console output buffer */
 177                 if (sclp_conbuf == NULL) {
 178                         if (list_empty(&sclp_con_pages))
 179                                 sclp_console_full++;
 180                         while (list_empty(&sclp_con_pages)) {
 181                                 if (sclp_con_suspended)
 182                                         goto out;
 183                                 if (sclp_console_drop_buffer())
 184                                         break;
 185                                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 186                                 sclp_sync_wait();
 187                                 spin_lock_irqsave(&sclp_con_lock, flags);
 188                         }
 189                         page = sclp_con_pages.next;
 190                         list_del((struct list_head *) page);
 191                         sclp_conbuf = sclp_make_buffer(page, sclp_con_columns,
 192                                                        sclp_con_width_htab);
 193                 }
 194                 /* try to write the string to the current output buffer */
 195                 written = sclp_write(sclp_conbuf, (const unsigned char *)
 196                                      message, count);
 197                 if (written == count)
 198                         break;
 199                 /*
 200                  * Not all characters could be written to the current
 201                  * output buffer. Emit the buffer, create a new buffer
 202                  * and then output the rest of the string.
 203                  */
 204                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 205                 sclp_conbuf_emit();
 206                 spin_lock_irqsave(&sclp_con_lock, flags);
 207                 message += written;
 208                 count -= written;
 209         } while (count > 0);
 210         /* Setup timer to output current console buffer after 1/10 second */
 211         if (sclp_conbuf != NULL && sclp_chars_in_buffer(sclp_conbuf) != 0 &&
 212             !timer_pending(&sclp_con_timer)) {
 213                 init_timer(&sclp_con_timer);
 214                 sclp_con_timer.function = sclp_console_timeout;
 215                 sclp_con_timer.data = 0UL;
 216                 sclp_con_timer.expires = jiffies + HZ/10;
 217                 add_timer(&sclp_con_timer);
 218         }
 219 out:
 220         spin_unlock_irqrestore(&sclp_con_lock, flags);
 221 }
 222
 223 static struct tty_driver *
 224 sclp_console_device(struct console *c, int *index)
 225 {
 226         *index = c->index;
 227         return sclp_tty_driver;
 228 }
 229
 230 /*
 231  * Make sure that all buffers will be flushed to the SCLP.
 232  */
 233 static void
 234 sclp_console_flush(void)
 235 {
 236         sclp_conbuf_emit();
 237         sclp_console_sync_queue();
 238 }
 239
 240 /*
 241  * Resume console: If there are cached messages, emit them.
 242  */
 243 static void sclp_console_resume(void)
 244 {
 245         unsigned long flags;
 246
 247         spin_lock_irqsave(&sclp_con_lock, flags);
 248         sclp_con_suspended = 0;
 249         spin_unlock_irqrestore(&sclp_con_lock, flags);
 250         sclp_conbuf_emit();
 251 }
 252
 253 /*
 254  * Suspend console: Set suspend flag and flush console
 255  */
 256 static void sclp_console_suspend(void)
 257 {
 258         unsigned long flags;
 259
 260         spin_lock_irqsave(&sclp_con_lock, flags);
 261         sclp_con_suspended = 1;
 262         spin_unlock_irqrestore(&sclp_con_lock, flags);
 263         sclp_console_flush();
 264 }
 265
 266 static int sclp_console_notify(struct notifier_block *self,
 267                                unsigned long event, void *data)
 268 {
 269         sclp_console_flush();
 270         return NOTIFY_OK;
 271 }
 272
 273 static struct notifier_block on_panic_nb = {
 274         .notifier_call = sclp_console_notify,
 275         .priority = SCLP_PANIC_PRIO_CLIENT,
 276 };
 277
 278 static struct notifier_block on_reboot_nb = {
 279         .notifier_call = sclp_console_notify,
 280         .priority = 1,
 281 };
 282
 283 /*
 284  * used to register the SCLP console to the kernel and to
 285  * give printk necessary information
 286  */
 287 static struct console sclp_console =
 288 {
 289         .name = sclp_console_name,
 290         .write = sclp_console_write,
 291         .device = sclp_console_device,
 292         .flags = CON_PRINTBUFFER,
 293         .index = 0 /* ttyS0 */
 294 };
 295
 296 /*
 297  * This function is called for SCLP suspend and resume events.
 298  */
 299 void sclp_console_pm_event(enum sclp_pm_event sclp_pm_event)
 300 {
 301         switch (sclp_pm_event) {
 302         case SCLP_PM_EVENT_FREEZE:
 303                 sclp_console_suspend();
 304                 break;
 305         case SCLP_PM_EVENT_RESTORE:
 306         case SCLP_PM_EVENT_THAW:
 307                 sclp_console_resume();
 308                 break;
 309         }
 310 }
 311
 312 /*
 313  * called by console_init() in drivers/char/tty_io.c at boot-time.
 314  */
 315 static int __init
 316 sclp_console_init(void)
 317 {
 318         void *page;
 319         int i;
 320         int rc;
 321
 322         if (!CONSOLE_IS_SCLP)
 323                 return 0;
 324         rc = sclp_rw_init();
 325         if (rc)
 326                 return rc;
 327         /* Allocate pages for output buffering */
 328         INIT_LIST_HEAD(&sclp_con_pages);
 329         for (i = 0; i < sclp_console_pages; i++) {
 330                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 331                 list_add_tail(page, &sclp_con_pages);
 332         }
 333         INIT_LIST_HEAD(&sclp_con_outqueue);
 334         spin_lock_init(&sclp_con_lock);
 335         sclp_conbuf = NULL;
 336         init_timer(&sclp_con_timer);
 337
 338         /* Set output format */
 339         if (MACHINE_IS_VM)
 340                 /*
 341                  * save 4 characters for the CPU number
 342                  * written at start of each line by VM/CP
 343                  */
 344                 sclp_con_columns = 76;
 345         else
 346                 sclp_con_columns = 80;
 347         sclp_con_width_htab = 8;
 348
 349         /* enable printk-access to this driver */
 350         atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
 351         register_reboot_notifier(&on_reboot_nb);
 352         register_console(&sclp_console);
 353         return 0;
 354 }
 355
 356 console_initcall(sclp_console_init);