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/config.h>
  12 #include <linux/kmod.h>
  13 #include <linux/console.h>
  14 #include <linux/init.h>
  15 #include <linux/timer.h>
  16 #include <linux/jiffies.h>
  17 #include <linux/bootmem.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_CON_PRINT_HEADER "sclp console driver: "
  25
  26 #define sclp_console_major 4            /* TTYAUX_MAJOR */
  27 #define sclp_console_minor 64
  28 #define sclp_console_name  "ttyS"
  29
  30 /* Lock to guard over changes to global variables */
  31 static spinlock_t sclp_con_lock;
  32 /* List of free pages that can be used for console output buffering */
  33 static struct list_head sclp_con_pages;
  34 /* List of full struct sclp_buffer structures ready for output */
  35 static struct list_head sclp_con_outqueue;
  36 /* Counter how many buffers are emitted (max 1) and how many */
  37 /* are on the output queue. */
  38 static int sclp_con_buffer_count;
  39 /* Pointer to current console buffer */
  40 static struct sclp_buffer *sclp_conbuf;
  41 /* Timer for delayed output of console messages */
  42 static struct timer_list sclp_con_timer;
  43
  44 /* Output format for console messages */
  45 static unsigned short sclp_con_columns;
  46 static unsigned short sclp_con_width_htab;
  47
  48 static void
  49 sclp_conbuf_callback(struct sclp_buffer *buffer, int rc)
  50 {
  51         unsigned long flags;
  52         void *page;
  53
  54         do {
  55                 page = sclp_unmake_buffer(buffer);
  56                 spin_lock_irqsave(&sclp_con_lock, flags);
  57                 /* Remove buffer from outqueue */
  58                 list_del(&buffer->list);
  59                 sclp_con_buffer_count--;
  60                 list_add_tail((struct list_head *) page, &sclp_con_pages);
  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_entry(sclp_con_outqueue.next,
  65                                             struct sclp_buffer, list);
  66                 spin_unlock_irqrestore(&sclp_con_lock, flags);
  67         } while (buffer && sclp_emit_buffer(buffer, sclp_conbuf_callback));
  68 }
  69
  70 static inline void
  71 sclp_conbuf_emit(void)
  72 {
  73         struct sclp_buffer* buffer;
  74         unsigned long flags;
  75         int count;
  76         int rc;
  77
  78         spin_lock_irqsave(&sclp_con_lock, flags);
  79         buffer = sclp_conbuf;
  80         sclp_conbuf = NULL;
  81         if (buffer == NULL) {
  82                 spin_unlock_irqrestore(&sclp_con_lock, flags);
  83                 return;
  84         }
  85         list_add_tail(&buffer->list, &sclp_con_outqueue);
  86         count = sclp_con_buffer_count++;
  87         spin_unlock_irqrestore(&sclp_con_lock, flags);
  88         if (count)
  89                 return;
  90         rc = sclp_emit_buffer(buffer, sclp_conbuf_callback);
  91         if (rc)
  92                 sclp_conbuf_callback(buffer, rc);
  93 }
  94
  95 /*
  96  * When this routine is called from the timer then we flush the
  97  * temporary write buffer without further waiting on a final new line.
  98  */
  99 static void
 100 sclp_console_timeout(unsigned long data)
 101 {
 102         sclp_conbuf_emit();
 103 }
 104
 105 /*
 106  * Writes the given message to S390 system console
 107  */
 108 static void
 109 sclp_console_write(struct console *console, const char *message,
 110                    unsigned int count)
 111 {
 112         unsigned long flags;
 113         void *page;
 114         int written;
 115
 116         if (count == 0)
 117                 return;
 118         spin_lock_irqsave(&sclp_con_lock, flags);
 119         /*
 120          * process escape characters, write message into buffer,
 121          * send buffer to SCLP
 122          */
 123         do {
 124                 /* make sure we have a console output buffer */
 125                 if (sclp_conbuf == NULL) {
 126                         while (list_empty(&sclp_con_pages)) {
 127                                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 128                                 sclp_sync_wait();
 129                                 spin_lock_irqsave(&sclp_con_lock, flags);
 130                         }
 131                         page = sclp_con_pages.next;
 132                         list_del((struct list_head *) page);
 133                         sclp_conbuf = sclp_make_buffer(page, sclp_con_columns,
 134                                                        sclp_con_width_htab);
 135                 }
 136                 /* try to write the string to the current output buffer */
 137                 written = sclp_write(sclp_conbuf, (const unsigned char *)
 138                                      message, count);
 139                 if (written == count)
 140                         break;
 141                 /*
 142                  * Not all characters could be written to the current
 143                  * output buffer. Emit the buffer, create a new buffer
 144                  * and then output the rest of the string.
 145                  */
 146                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 147                 sclp_conbuf_emit();
 148                 spin_lock_irqsave(&sclp_con_lock, flags);
 149                 message += written;
 150                 count -= written;
 151         } while (count > 0);
 152         /* Setup timer to output current console buffer after 1/10 second */
 153         if (sclp_conbuf != NULL && sclp_chars_in_buffer(sclp_conbuf) != 0 &&
 154             !timer_pending(&sclp_con_timer)) {
 155                 init_timer(&sclp_con_timer);
 156                 sclp_con_timer.function = sclp_console_timeout;
 157                 sclp_con_timer.data = 0UL;
 158                 sclp_con_timer.expires = jiffies + HZ/10;
 159                 add_timer(&sclp_con_timer);
 160         }
 161         spin_unlock_irqrestore(&sclp_con_lock, flags);
 162 }
 163
 164 static struct tty_driver *
 165 sclp_console_device(struct console *c, int *index)
 166 {
 167         *index = c->index;
 168         return sclp_tty_driver;
 169 }
 170
 171 /*
 172  * This routine is called from panic when the kernel
 173  * is going to give up. We have to make sure that all buffers
 174  * will be flushed to the SCLP.
 175  */
 176 static void
 177 sclp_console_unblank(void)
 178 {
 179         unsigned long flags;
 180
 181         sclp_conbuf_emit();
 182         spin_lock_irqsave(&sclp_con_lock, flags);
 183         if (timer_pending(&sclp_con_timer))
 184                 del_timer(&sclp_con_timer);
 185         while (sclp_con_buffer_count > 0) {
 186                 spin_unlock_irqrestore(&sclp_con_lock, flags);
 187                 sclp_sync_wait();
 188                 spin_lock_irqsave(&sclp_con_lock, flags);
 189         }
 190         spin_unlock_irqrestore(&sclp_con_lock, flags);
 191 }
 192
 193 /*
 194  * used to register the SCLP console to the kernel and to
 195  * give printk necessary information
 196  */
 197 static struct console sclp_console =
 198 {
 199         .name = sclp_console_name,
 200         .write = sclp_console_write,
 201         .device = sclp_console_device,
 202         .unblank = sclp_console_unblank,
 203         .flags = CON_PRINTBUFFER,
 204         .index = 0 /* ttyS0 */
 205 };
 206
 207 /*
 208  * called by console_init() in drivers/char/tty_io.c at boot-time.
 209  */
 210 static int __init
 211 sclp_console_init(void)
 212 {
 213         void *page;
 214         int i;
 215         int rc;
 216
 217         if (!CONSOLE_IS_SCLP)
 218                 return 0;
 219         rc = sclp_rw_init();
 220         if (rc)
 221                 return rc;
 222         /* Allocate pages for output buffering */
 223         INIT_LIST_HEAD(&sclp_con_pages);
 224         for (i = 0; i < MAX_CONSOLE_PAGES; i++) {
 225                 page = alloc_bootmem_low_pages(PAGE_SIZE);
 226                 if (page == NULL)
 227                         return -ENOMEM;
 228                 list_add_tail((struct list_head *) page, &sclp_con_pages);
 229         }
 230         INIT_LIST_HEAD(&sclp_con_outqueue);
 231         spin_lock_init(&sclp_con_lock);
 232         sclp_con_buffer_count = 0;
 233         sclp_conbuf = NULL;
 234         init_timer(&sclp_con_timer);
 235
 236         /* Set output format */
 237         if (MACHINE_IS_VM)
 238                 /*
 239                  * save 4 characters for the CPU number
 240                  * written at start of each line by VM/CP
 241                  */
 242                 sclp_con_columns = 76;
 243         else
 244                 sclp_con_columns = 80;
 245         sclp_con_width_htab = 8;
 246
 247         /* enable printk-access to this driver */
 248         register_console(&sclp_console);
 249         return 0;
 250 }
 251
 252 console_initcall(sclp_console_init);