drivers/s390/char/sclp_con.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * SCLP line mode console driver
   4  *
   5  * Copyright IBM Corp. 1999, 2009
   6  * Author(s): Martin Peschke <mpeschke@de.ibm.com>
   7  *            Martin Schwidefsky <schwidefsky@de.ibm.com>
   8  */
   9
  10 #include <linux/kmod.h>
  11 #include <linux/console.h>
  12 #include <linux/init.h>
  13 #include <linux/timer.h>
  14 #include <linux/jiffies.h>
  15 #include <linux/termios.h>
  16 #include <linux/err.h>
  17 #include <linux/reboot.h>
  18 #include <linux/gfp.h>
  19
  20 #include "sclp.h"
  21 #include "sclp_rw.h"
  22 #include "sclp_tty.h"
  23
  24 #define sclp_console_major 4            /* TTYAUX_MAJOR */
  25 #define sclp_console_minor 64
  26 #define sclp_console_name  "ttyS"
  27
  28 /* Lock to guard over changes to global variables */
  29 static spinlock_t sclp_con_lock;
  30 /* List of free pages that can be used for console output buffering */
  31 static struct list_head sclp_con_pages;
  32 /* List of full struct sclp_buffer structures ready for output */
  33 static struct list_head sclp_con_outqueue;
  34 /* Pointer to current console buffer */
  35 static struct sclp_buffer *sclp_conbuf;
  36 /* Timer for delayed output of console messages */
  37 static struct timer_list sclp_con_timer;
  38 /* Suspend mode flag */
  39 static int sclp_con_suspended;
  40 /* Flag that output queue is currently running */
  41 static int sclp_con_queue_running;
  42
  43 /* Output format for console messages */
  44 static unsigned short sclp_con_columns;
  45 static unsigned short sclp_con_width_htab;
  46
  47 static void
  48 sclp_conbuf_callback(struct sclp_buffer *buffer, int rc)
  49 {
  50         unsigned long flags;
  51         void *page;
  52
  53         do {
  54                 page = sclp_unmake_buffer(buffer);
  55                 spin_lock_irqsave(&sclp_con_lock, flags);
  56
  57                 /* Remove buffer from outqueue */
  58                 list_del(&buffer->list);
  59                 list_add_tail((struct list_head *) page, &sclp_con_pages);
  60
  61                 /* Check if there is a pending buffer on the out queue. */
  62                 buffer = NULL;
  63                 if (!list_empty(&sclp_con_outqueue))
  64                         buffer = list_first_entry(&sclp_con_outqueue,
  65                                                   struct sclp_buffer, list);
  66                 if (!buffer || sclp_con_suspended) {
  67                         sclp_con_queue_running = 0;
  68                         spin_unlock_irqrestore(&sclp_con_lock, flags);
  69                         break;
  70                 }
  71                 spin_unlock_irqrestore(&sclp_con_lock, flags);
  72         } while (sclp_emit_buffer(buffer, sclp_conbuf_callback));
  73 }
  74
  75 /*
  76  * Finalize and emit first pending buffer.
  77  */
  78 static void sclp_conbuf_emit(void)
  79 {
  80         struct sclp_buffer* buffer;
  81         unsigned long flags;
  82         int rc;
  83
  84         spin_lock_irqsave(&sclp_con_lock, flags);
  85         if (sclp_conbuf)
  86                 list_add_tail(&sclp_conbuf->list, &sclp_con_outqueue);
  87         sclp_conbuf = NULL;
  88         if (sclp_con_queue_running || sclp_con_suspended)
  89                 goto out_unlock;
  90         if (list_empty(&sclp_con_outqueue))
  91                 goto out_unlock;
  92         buffer = list_first_entry(&sclp_con_outqueue, struct sclp_buffer,
  93                                   list);
  94         sclp_con_queue_running = 1;
  95         spin_unlock_irqrestore(&sclp_con_lock, flags);
  96
  97         rc = sclp_emit_buffer(buffer, sclp_conbuf_callback);
  98         if (rc)
  99                 sclp_conbuf_callback(buffer, rc);
 100         return;
 101 out_unlock:
 102         spin_unlock_irqrestore(&sclp_con_lock, flags);
 103 }
 104
 105 /*
 106  * Wait until out queue is empty
 107  */
 108 static void sclp_console_sync_queue(void)
 109 {
 110         unsigned long flags;
 111
 112         spin_lock_irqsave(&sclp_con_lock, flags);
 113         if (timer_pending(&sclp_con_timer))
 114                 del_timer(&sclp_con_timer);
 115         while (sclp_con_queue_running) {
 116                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 117                 sclp_sync_wait();
 118                 spin_lock_irqsave(&sclp_con_lock, flags);
 119         }
 120         spin_unlock_irqrestore(&sclp_con_lock, flags);
 121 }
 122
 123 /*
 124  * When this routine is called from the timer then we flush the
 125  * temporary write buffer without further waiting on a final new line.
 126  */
 127 static void
 128 sclp_console_timeout(unsigned long data)
 129 {
 130         sclp_conbuf_emit();
 131 }
 132
 133 /*
 134  * Drop oldest console buffer if sclp_con_drop is set
 135  */
 136 static int
 137 sclp_console_drop_buffer(void)
 138 {
 139         struct list_head *list;
 140         struct sclp_buffer *buffer;
 141         void *page;
 142
 143         if (!sclp_console_drop)
 144                 return 0;
 145         list = sclp_con_outqueue.next;
 146         if (sclp_con_queue_running)
 147                 /* The first element is in I/O */
 148                 list = list->next;
 149         if (list == &sclp_con_outqueue)
 150                 return 0;
 151         list_del(list);
 152         buffer = list_entry(list, struct sclp_buffer, list);
 153         page = sclp_unmake_buffer(buffer);
 154         list_add_tail((struct list_head *) page, &sclp_con_pages);
 155         return 1;
 156 }
 157
 158 /*
 159  * Writes the given message to S390 system console
 160  */
 161 static void
 162 sclp_console_write(struct console *console, const char *message,
 163                    unsigned int count)
 164 {
 165         unsigned long flags;
 166         void *page;
 167         int written;
 168
 169         if (count == 0)
 170                 return;
 171         spin_lock_irqsave(&sclp_con_lock, flags);
 172         /*
 173          * process escape characters, write message into buffer,
 174          * send buffer to SCLP
 175          */
 176         do {
 177                 /* make sure we have a console output buffer */
 178                 if (sclp_conbuf == NULL) {
 179                         if (list_empty(&sclp_con_pages))
 180                                 sclp_console_full++;
 181                         while (list_empty(&sclp_con_pages)) {
 182                                 if (sclp_con_suspended)
 183                                         goto out;
 184                                 if (sclp_console_drop_buffer())
 185                                         break;
 186                                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 187                                 sclp_sync_wait();
 188                                 spin_lock_irqsave(&sclp_con_lock, flags);
 189                         }
 190                         page = sclp_con_pages.next;
 191                         list_del((struct list_head *) page);
 192                         sclp_conbuf = sclp_make_buffer(page, sclp_con_columns,
 193                                                        sclp_con_width_htab);
 194                 }
 195                 /* try to write the string to the current output buffer */
 196                 written = sclp_write(sclp_conbuf, (const unsigned char *)
 197                                      message, count);
 198                 if (written == count)
 199                         break;
 200                 /*
 201                  * Not all characters could be written to the current
 202                  * output buffer. Emit the buffer, create a new buffer
 203                  * and then output the rest of the string.
 204                  */
 205                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 206                 sclp_conbuf_emit();
 207                 spin_lock_irqsave(&sclp_con_lock, flags);
 208                 message += written;
 209                 count -= written;
 210         } while (count > 0);
 211         /* Setup timer to output current console buffer after 1/10 second */
 212         if (sclp_conbuf != NULL && sclp_chars_in_buffer(sclp_conbuf) != 0 &&
 213             !timer_pending(&sclp_con_timer)) {
 214                 setup_timer(&sclp_con_timer, sclp_console_timeout, 0UL);
 215                 mod_timer(&sclp_con_timer, jiffies + HZ / 10);
 216         }
 217 out:
 218         spin_unlock_irqrestore(&sclp_con_lock, flags);
 219 }
 220
 221 static struct tty_driver *
 222 sclp_console_device(struct console *c, int *index)
 223 {
 224         *index = c->index;
 225         return sclp_tty_driver;
 226 }
 227
 228 /*
 229  * Make sure that all buffers will be flushed to the SCLP.
 230  */
 231 static void
 232 sclp_console_flush(void)
 233 {
 234         sclp_conbuf_emit();
 235         sclp_console_sync_queue();
 236 }
 237
 238 /*
 239  * Resume console: If there are cached messages, emit them.
 240  */
 241 static void sclp_console_resume(void)
 242 {
 243         unsigned long flags;
 244
 245         spin_lock_irqsave(&sclp_con_lock, flags);
 246         sclp_con_suspended = 0;
 247         spin_unlock_irqrestore(&sclp_con_lock, flags);
 248         sclp_conbuf_emit();
 249 }
 250
 251 /*
 252  * Suspend console: Set suspend flag and flush console
 253  */
 254 static void sclp_console_suspend(void)
 255 {
 256         unsigned long flags;
 257
 258         spin_lock_irqsave(&sclp_con_lock, flags);
 259         sclp_con_suspended = 1;
 260         spin_unlock_irqrestore(&sclp_con_lock, flags);
 261         sclp_console_flush();
 262 }
 263
 264 static int sclp_console_notify(struct notifier_block *self,
 265                                unsigned long event, void *data)
 266 {
 267         sclp_console_flush();
 268         return NOTIFY_OK;
 269 }
 270
 271 static struct notifier_block on_panic_nb = {
 272         .notifier_call = sclp_console_notify,
 273         .priority = SCLP_PANIC_PRIO_CLIENT,
 274 };
 275
 276 static struct notifier_block on_reboot_nb = {
 277         .notifier_call = sclp_console_notify,
 278         .priority = 1,
 279 };
 280
 281 /*
 282  * used to register the SCLP console to the kernel and to
 283  * give printk necessary information
 284  */
 285 static struct console sclp_console =
 286 {
 287         .name = sclp_console_name,
 288         .write = sclp_console_write,
 289         .device = sclp_console_device,
 290         .flags = CON_PRINTBUFFER,
 291         .index = 0 /* ttyS0 */
 292 };
 293
 294 /*
 295  * This function is called for SCLP suspend and resume events.
 296  */
 297 void sclp_console_pm_event(enum sclp_pm_event sclp_pm_event)
 298 {
 299         switch (sclp_pm_event) {
 300         case SCLP_PM_EVENT_FREEZE:
 301                 sclp_console_suspend();
 302                 break;
 303         case SCLP_PM_EVENT_RESTORE:
 304         case SCLP_PM_EVENT_THAW:
 305                 sclp_console_resume();
 306                 break;
 307         }
 308 }
 309
 310 /*
 311  * called by console_init() in drivers/char/tty_io.c at boot-time.
 312  */
 313 static int __init
 314 sclp_console_init(void)
 315 {
 316         void *page;
 317         int i;
 318         int rc;
 319
 320         /* SCLP consoles are handled together */
 321         if (!(CONSOLE_IS_SCLP || CONSOLE_IS_VT220))
 322                 return 0;
 323         rc = sclp_rw_init();
 324         if (rc)
 325                 return rc;
 326         /* Allocate pages for output buffering */
 327         INIT_LIST_HEAD(&sclp_con_pages);
 328         for (i = 0; i < sclp_console_pages; i++) {
 329                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 330                 list_add_tail(page, &sclp_con_pages);
 331         }
 332         INIT_LIST_HEAD(&sclp_con_outqueue);
 333         spin_lock_init(&sclp_con_lock);
 334         sclp_conbuf = NULL;
 335         init_timer(&sclp_con_timer);
 336
 337         /* Set output format */
 338         if (MACHINE_IS_VM)
 339                 /*
 340                  * save 4 characters for the CPU number
 341                  * written at start of each line by VM/CP
 342                  */
 343                 sclp_con_columns = 76;
 344         else
 345                 sclp_con_columns = 80;
 346         sclp_con_width_htab = 8;
 347
 348         /* enable printk-access to this driver */
 349         atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
 350         register_reboot_notifier(&on_reboot_nb);
 351         register_console(&sclp_console);
 352         return 0;
 353 }
 354
 355 console_initcall(sclp_console_init);