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  * Writes the given message to S390 system console
 134  */
 135 static void
 136 sclp_console_write(struct console *console, const char *message,
 137                    unsigned int count)
 138 {
 139         unsigned long flags;
 140         void *page;
 141         int written;
 142
 143         if (count == 0)
 144                 return;
 145         spin_lock_irqsave(&sclp_con_lock, flags);
 146         /*
 147          * process escape characters, write message into buffer,
 148          * send buffer to SCLP
 149          */
 150         do {
 151                 /* make sure we have a console output buffer */
 152                 if (sclp_conbuf == NULL) {
 153                         while (list_empty(&sclp_con_pages)) {
 154                                 if (sclp_con_suspended)
 155                                         goto out;
 156                                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 157                                 sclp_sync_wait();
 158                                 spin_lock_irqsave(&sclp_con_lock, flags);
 159                         }
 160                         page = sclp_con_pages.next;
 161                         list_del((struct list_head *) page);
 162                         sclp_conbuf = sclp_make_buffer(page, sclp_con_columns,
 163                                                        sclp_con_width_htab);
 164                 }
 165                 /* try to write the string to the current output buffer */
 166                 written = sclp_write(sclp_conbuf, (const unsigned char *)
 167                                      message, count);
 168                 if (written == count)
 169                         break;
 170                 /*
 171                  * Not all characters could be written to the current
 172                  * output buffer. Emit the buffer, create a new buffer
 173                  * and then output the rest of the string.
 174                  */
 175                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 176                 sclp_conbuf_emit();
 177                 spin_lock_irqsave(&sclp_con_lock, flags);
 178                 message += written;
 179                 count -= written;
 180         } while (count > 0);
 181         /* Setup timer to output current console buffer after 1/10 second */
 182         if (sclp_conbuf != NULL && sclp_chars_in_buffer(sclp_conbuf) != 0 &&
 183             !timer_pending(&sclp_con_timer)) {
 184                 init_timer(&sclp_con_timer);
 185                 sclp_con_timer.function = sclp_console_timeout;
 186                 sclp_con_timer.data = 0UL;
 187                 sclp_con_timer.expires = jiffies + HZ/10;
 188                 add_timer(&sclp_con_timer);
 189         }
 190 out:
 191         spin_unlock_irqrestore(&sclp_con_lock, flags);
 192 }
 193
 194 static struct tty_driver *
 195 sclp_console_device(struct console *c, int *index)
 196 {
 197         *index = c->index;
 198         return sclp_tty_driver;
 199 }
 200
 201 /*
 202  * Make sure that all buffers will be flushed to the SCLP.
 203  */
 204 static void
 205 sclp_console_flush(void)
 206 {
 207         sclp_conbuf_emit();
 208         sclp_console_sync_queue();
 209 }
 210
 211 /*
 212  * Resume console: If there are cached messages, emit them.
 213  */
 214 static void sclp_console_resume(void)
 215 {
 216         unsigned long flags;
 217
 218         spin_lock_irqsave(&sclp_con_lock, flags);
 219         sclp_con_suspended = 0;
 220         spin_unlock_irqrestore(&sclp_con_lock, flags);
 221         sclp_conbuf_emit();
 222 }
 223
 224 /*
 225  * Suspend console: Set suspend flag and flush console
 226  */
 227 static void sclp_console_suspend(void)
 228 {
 229         unsigned long flags;
 230
 231         spin_lock_irqsave(&sclp_con_lock, flags);
 232         sclp_con_suspended = 1;
 233         spin_unlock_irqrestore(&sclp_con_lock, flags);
 234         sclp_console_flush();
 235 }
 236
 237 static int sclp_console_notify(struct notifier_block *self,
 238                                unsigned long event, void *data)
 239 {
 240         sclp_console_flush();
 241         return NOTIFY_OK;
 242 }
 243
 244 static struct notifier_block on_panic_nb = {
 245         .notifier_call = sclp_console_notify,
 246         .priority = SCLP_PANIC_PRIO_CLIENT,
 247 };
 248
 249 static struct notifier_block on_reboot_nb = {
 250         .notifier_call = sclp_console_notify,
 251         .priority = 1,
 252 };
 253
 254 /*
 255  * used to register the SCLP console to the kernel and to
 256  * give printk necessary information
 257  */
 258 static struct console sclp_console =
 259 {
 260         .name = sclp_console_name,
 261         .write = sclp_console_write,
 262         .device = sclp_console_device,
 263         .flags = CON_PRINTBUFFER,
 264         .index = 0 /* ttyS0 */
 265 };
 266
 267 /*
 268  * This function is called for SCLP suspend and resume events.
 269  */
 270 void sclp_console_pm_event(enum sclp_pm_event sclp_pm_event)
 271 {
 272         switch (sclp_pm_event) {
 273         case SCLP_PM_EVENT_FREEZE:
 274                 sclp_console_suspend();
 275                 break;
 276         case SCLP_PM_EVENT_RESTORE:
 277         case SCLP_PM_EVENT_THAW:
 278                 sclp_console_resume();
 279                 break;
 280         }
 281 }
 282
 283 /*
 284  * called by console_init() in drivers/char/tty_io.c at boot-time.
 285  */
 286 static int __init
 287 sclp_console_init(void)
 288 {
 289         void *page;
 290         int i;
 291         int rc;
 292
 293         if (!CONSOLE_IS_SCLP)
 294                 return 0;
 295         rc = sclp_rw_init();
 296         if (rc)
 297                 return rc;
 298         /* Allocate pages for output buffering */
 299         INIT_LIST_HEAD(&sclp_con_pages);
 300         for (i = 0; i < MAX_CONSOLE_PAGES; i++) {
 301                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 302                 list_add_tail(page, &sclp_con_pages);
 303         }
 304         INIT_LIST_HEAD(&sclp_con_outqueue);
 305         spin_lock_init(&sclp_con_lock);
 306         sclp_conbuf = NULL;
 307         init_timer(&sclp_con_timer);
 308
 309         /* Set output format */
 310         if (MACHINE_IS_VM)
 311                 /*
 312                  * save 4 characters for the CPU number
 313                  * written at start of each line by VM/CP
 314                  */
 315                 sclp_con_columns = 76;
 316         else
 317                 sclp_con_columns = 80;
 318         sclp_con_width_htab = 8;
 319
 320         /* enable printk-access to this driver */
 321         atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
 322         register_reboot_notifier(&on_reboot_nb);
 323         register_console(&sclp_console);
 324         return 0;
 325 }
 326
 327 console_initcall(sclp_console_init);