drivers/s390/char/sclp_con.c

   1 /*
   2  *  drivers/s390/char/sclp_con.c
   3  *    SCLP line mode console driver
   4  *
   5  *  S390 version
   6  *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
   7  *    Author(s): Martin Peschke <mpeschke@de.ibm.com>
   8  *               Martin Schwidefsky <schwidefsky@de.ibm.com>
   9  */
  10
  11 #include <linux/kmod.h>
  12 #include <linux/console.h>
  13 #include <linux/init.h>
  14 #include <linux/timer.h>
  15 #include <linux/jiffies.h>
  16 #include <linux/bootmem.h>
  17 #include <linux/termios.h>
  18 #include <linux/err.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 /* Counter how many buffers are emitted (max 1) and how many */
  35 /* are on the output queue. */
  36 static int sclp_con_buffer_count;
  37 /* Pointer to current console buffer */
  38 static struct sclp_buffer *sclp_conbuf;
  39 /* Timer for delayed output of console messages */
  40 static struct timer_list sclp_con_timer;
  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                 /* Remove buffer from outqueue */
  56                 list_del(&buffer->list);
  57                 sclp_con_buffer_count--;
  58                 list_add_tail((struct list_head *) page, &sclp_con_pages);
  59                 /* Check if there is a pending buffer on the out queue. */
  60                 buffer = NULL;
  61                 if (!list_empty(&sclp_con_outqueue))
  62                         buffer = list_entry(sclp_con_outqueue.next,
  63                                             struct sclp_buffer, list);
  64                 spin_unlock_irqrestore(&sclp_con_lock, flags);
  65         } while (buffer && sclp_emit_buffer(buffer, sclp_conbuf_callback));
  66 }
  67
  68 static void
  69 sclp_conbuf_emit(void)
  70 {
  71         struct sclp_buffer* buffer;
  72         unsigned long flags;
  73         int count;
  74         int rc;
  75
  76         spin_lock_irqsave(&sclp_con_lock, flags);
  77         buffer = sclp_conbuf;
  78         sclp_conbuf = NULL;
  79         if (buffer == NULL) {
  80                 spin_unlock_irqrestore(&sclp_con_lock, flags);
  81                 return;
  82         }
  83         list_add_tail(&buffer->list, &sclp_con_outqueue);
  84         count = sclp_con_buffer_count++;
  85         spin_unlock_irqrestore(&sclp_con_lock, flags);
  86         if (count)
  87                 return;
  88         rc = sclp_emit_buffer(buffer, sclp_conbuf_callback);
  89         if (rc)
  90                 sclp_conbuf_callback(buffer, rc);
  91 }
  92
  93 /*
  94  * When this routine is called from the timer then we flush the
  95  * temporary write buffer without further waiting on a final new line.
  96  */
  97 static void
  98 sclp_console_timeout(unsigned long data)
  99 {
 100         sclp_conbuf_emit();
 101 }
 102
 103 /*
 104  * Writes the given message to S390 system console
 105  */
 106 static void
 107 sclp_console_write(struct console *console, const char *message,
 108                    unsigned int count)
 109 {
 110         unsigned long flags;
 111         void *page;
 112         int written;
 113
 114         if (count == 0)
 115                 return;
 116         spin_lock_irqsave(&sclp_con_lock, flags);
 117         /*
 118          * process escape characters, write message into buffer,
 119          * send buffer to SCLP
 120          */
 121         do {
 122                 /* make sure we have a console output buffer */
 123                 if (sclp_conbuf == NULL) {
 124                         while (list_empty(&sclp_con_pages)) {
 125                                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 126                                 sclp_sync_wait();
 127                                 spin_lock_irqsave(&sclp_con_lock, flags);
 128                         }
 129                         page = sclp_con_pages.next;
 130                         list_del((struct list_head *) page);
 131                         sclp_conbuf = sclp_make_buffer(page, sclp_con_columns,
 132                                                        sclp_con_width_htab);
 133                 }
 134                 /* try to write the string to the current output buffer */
 135                 written = sclp_write(sclp_conbuf, (const unsigned char *)
 136                                      message, count);
 137                 if (written == count)
 138                         break;
 139                 /*
 140                  * Not all characters could be written to the current
 141                  * output buffer. Emit the buffer, create a new buffer
 142                  * and then output the rest of the string.
 143                  */
 144                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 145                 sclp_conbuf_emit();
 146                 spin_lock_irqsave(&sclp_con_lock, flags);
 147                 message += written;
 148                 count -= written;
 149         } while (count > 0);
 150         /* Setup timer to output current console buffer after 1/10 second */
 151         if (sclp_conbuf != NULL && sclp_chars_in_buffer(sclp_conbuf) != 0 &&
 152             !timer_pending(&sclp_con_timer)) {
 153                 init_timer(&sclp_con_timer);
 154                 sclp_con_timer.function = sclp_console_timeout;
 155                 sclp_con_timer.data = 0UL;
 156                 sclp_con_timer.expires = jiffies + HZ/10;
 157                 add_timer(&sclp_con_timer);
 158         }
 159         spin_unlock_irqrestore(&sclp_con_lock, flags);
 160 }
 161
 162 static struct tty_driver *
 163 sclp_console_device(struct console *c, int *index)
 164 {
 165         *index = c->index;
 166         return sclp_tty_driver;
 167 }
 168
 169 /*
 170  * This routine is called from panic when the kernel
 171  * is going to give up. We have to make sure that all buffers
 172  * will be flushed to the SCLP.
 173  */
 174 static void
 175 sclp_console_unblank(void)
 176 {
 177         unsigned long flags;
 178
 179         sclp_conbuf_emit();
 180         spin_lock_irqsave(&sclp_con_lock, flags);
 181         if (timer_pending(&sclp_con_timer))
 182                 del_timer(&sclp_con_timer);
 183         while (sclp_con_buffer_count > 0) {
 184                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 185                 sclp_sync_wait();
 186                 spin_lock_irqsave(&sclp_con_lock, flags);
 187         }
 188         spin_unlock_irqrestore(&sclp_con_lock, flags);
 189 }
 190
 191 /*
 192  * used to register the SCLP console to the kernel and to
 193  * give printk necessary information
 194  */
 195 static struct console sclp_console =
 196 {
 197         .name = sclp_console_name,
 198         .write = sclp_console_write,
 199         .device = sclp_console_device,
 200         .unblank = sclp_console_unblank,
 201         .flags = CON_PRINTBUFFER,
 202         .index = 0 /* ttyS0 */
 203 };
 204
 205 /*
 206  * called by console_init() in drivers/char/tty_io.c at boot-time.
 207  */
 208 static int __init
 209 sclp_console_init(void)
 210 {
 211         void *page;
 212         int i;
 213         int rc;
 214
 215         if (!CONSOLE_IS_SCLP)
 216                 return 0;
 217         rc = sclp_rw_init();
 218         if (rc)
 219                 return rc;
 220         /* Allocate pages for output buffering */
 221         INIT_LIST_HEAD(&sclp_con_pages);
 222         for (i = 0; i < MAX_CONSOLE_PAGES; i++) {
 223                 page = alloc_bootmem_low_pages(PAGE_SIZE);
 224                 list_add_tail((struct list_head *) page, &sclp_con_pages);
 225         }
 226         INIT_LIST_HEAD(&sclp_con_outqueue);
 227         spin_lock_init(&sclp_con_lock);
 228         sclp_con_buffer_count = 0;
 229         sclp_conbuf = NULL;
 230         init_timer(&sclp_con_timer);
 231
 232         /* Set output format */
 233         if (MACHINE_IS_VM)
 234                 /*
 235                  * save 4 characters for the CPU number
 236                  * written at start of each line by VM/CP
 237                  */
 238                 sclp_con_columns = 76;
 239         else
 240                 sclp_con_columns = 80;
 241         sclp_con_width_htab = 8;
 242
 243         /* enable printk-access to this driver */
 244         register_console(&sclp_console);
 245         return 0;
 246 }
 247
 248 console_initcall(sclp_console_init);