drivers/s390/char/sclp_rw.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * driver: reading from and writing to system console on S/390 via SCLP
   4  *
   5  * Copyright IBM Corp. 1999, 2009
   6  *
   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/types.h>
  13 #include <linux/err.h>
  14 #include <linux/string.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/ctype.h>
  17 #include <linux/uaccess.h>
  18
  19 #include "sclp.h"
  20 #include "sclp_rw.h"
  21
  22 /*
  23  * The room for the SCCB (only for writing) is not equal to a pages size
  24  * (as it is specified as the maximum size in the SCLP documentation)
  25  * because of the additional data structure described above.
  26  */
  27 #define MAX_SCCB_ROOM (PAGE_SIZE - sizeof(struct sclp_buffer))
  28
  29 /* Event type structure for write message and write priority message */
  30 static struct sclp_register sclp_rw_event = {
  31         .send_mask = EVTYP_MSG_MASK,
  32 };
  33
  34 /*
  35  * Setup a sclp write buffer. Gets a page as input (4K) and returns
  36  * a pointer to a struct sclp_buffer structure that is located at the
  37  * end of the input page. This reduces the buffer space by a few
  38  * bytes but simplifies things.
  39  */
  40 struct sclp_buffer *
  41 sclp_make_buffer(void *page, unsigned short columns, unsigned short htab)
  42 {
  43         struct sclp_buffer *buffer;
  44         struct sccb_header *sccb;
  45
  46         sccb = (struct sccb_header *) page;
  47         /*
  48          * We keep the struct sclp_buffer structure at the end
  49          * of the sccb page.
  50          */
  51         buffer = ((struct sclp_buffer *) ((addr_t) sccb + PAGE_SIZE)) - 1;
  52         buffer->sccb = sccb;
  53         buffer->retry_count = 0;
  54         buffer->messages = 0;
  55         buffer->char_sum = 0;
  56         buffer->current_line = NULL;
  57         buffer->current_length = 0;
  58         buffer->columns = columns;
  59         buffer->htab = htab;
  60
  61         /* initialize sccb */
  62         memset(sccb, 0, sizeof(struct sccb_header));
  63         sccb->length = sizeof(struct sccb_header);
  64
  65         return buffer;
  66 }
  67
  68 /*
  69  * Return a pointer to the original page that has been used to create
  70  * the buffer.
  71  */
  72 void *
  73 sclp_unmake_buffer(struct sclp_buffer *buffer)
  74 {
  75         return buffer->sccb;
  76 }
  77
  78 /*
  79  * Initialize a new message the end of the provided buffer with
  80  * enough room for max_len characters. Return 0 on success.
  81  */
  82 static int
  83 sclp_initialize_mto(struct sclp_buffer *buffer, int max_len)
  84 {
  85         struct sccb_header *sccb;
  86         struct msg_buf *msg;
  87         struct mdb *mdb;
  88         struct go *go;
  89         struct mto *mto;
  90         int msg_size;
  91
  92         /* max size of new message including message text  */
  93         msg_size = sizeof(struct msg_buf) + max_len;
  94
  95         /* check if current buffer sccb can contain the mto */
  96         sccb = buffer->sccb;
  97         if ((MAX_SCCB_ROOM - sccb->length) < msg_size)
  98                 return -ENOMEM;
  99
 100         msg = (struct msg_buf *)((addr_t) sccb + sccb->length);
 101         memset(msg, 0, sizeof(struct msg_buf));
 102         msg->header.length = sizeof(struct msg_buf);
 103         msg->header.type = EVTYP_MSG;
 104
 105         mdb = &msg->mdb;
 106         mdb->header.length = sizeof(struct mdb);
 107         mdb->header.type = 1;
 108         mdb->header.tag = 0xD4C4C240;   /* ebcdic "MDB " */
 109         mdb->header.revision_code = 1;
 110
 111         go = &mdb->go;
 112         go->length = sizeof(struct go);
 113         go->type = 1;
 114
 115         mto = &mdb->mto;
 116         mto->length = sizeof(struct mto);
 117         mto->type = 4;  /* message text object */
 118         mto->line_type_flags = LNTPFLGS_ENDTEXT; /* end text */
 119
 120         /* set pointer to first byte after struct mto. */
 121         buffer->current_msg = msg;
 122         buffer->current_line = (char *) (mto + 1);
 123         buffer->current_length = 0;
 124
 125         return 0;
 126 }
 127
 128 /*
 129  * Finalize message initialized by sclp_initialize_mto(),
 130  * updating the sizes of MTO, enclosing MDB, event buffer and SCCB.
 131  */
 132 static void
 133 sclp_finalize_mto(struct sclp_buffer *buffer)
 134 {
 135         struct sccb_header *sccb;
 136         struct msg_buf *msg;
 137
 138         /*
 139          * update values of sizes
 140          * (SCCB, Event(Message) Buffer, Message Data Block)
 141          */
 142         sccb = buffer->sccb;
 143         msg = buffer->current_msg;
 144         msg->header.length += buffer->current_length;
 145         msg->mdb.header.length += buffer->current_length;
 146         msg->mdb.mto.length += buffer->current_length;
 147         sccb->length += msg->header.length;
 148
 149         /*
 150          * count number of buffered messages (= number of Message Text
 151          * Objects) and number of buffered characters
 152          * for the SCCB currently used for buffering and at all
 153          */
 154         buffer->messages++;
 155         buffer->char_sum += buffer->current_length;
 156
 157         buffer->current_line = NULL;
 158         buffer->current_length = 0;
 159         buffer->current_msg = NULL;
 160 }
 161
 162 /*
 163  * processing of a message including escape characters,
 164  * returns number of characters written to the output sccb
 165  * ("processed" means that is not guaranteed that the character have already
 166  *  been sent to the SCLP but that it will be done at least next time the SCLP
 167  *  is not busy)
 168  */
 169 int
 170 sclp_write(struct sclp_buffer *buffer, const unsigned char *msg, int count)
 171 {
 172         int spaces, i_msg;
 173         int rc;
 174
 175         /*
 176          * parse msg for escape sequences (\t,\v ...) and put formated
 177          * msg into an mto (created by sclp_initialize_mto).
 178          *
 179          * We have to do this work ourselfs because there is no support for
 180          * these characters on the native machine and only partial support
 181          * under VM (Why does VM interpret \n but the native machine doesn't ?)
 182          *
 183          * Depending on i/o-control setting the message is always written
 184          * immediately or we wait for a final new line maybe coming with the
 185          * next message. Besides we avoid a buffer overrun by writing its
 186          * content.
 187          *
 188          * RESTRICTIONS:
 189          *
 190          * \r and \b work within one line because we are not able to modify
 191          * previous output that have already been accepted by the SCLP.
 192          *
 193          * \t combined with following \r is not correctly represented because
 194          * \t is expanded to some spaces but \r does not know about a
 195          * previous \t and decreases the current position by one column.
 196          * This is in order to a slim and quick implementation.
 197          */
 198         for (i_msg = 0; i_msg < count; i_msg++) {
 199                 switch (msg[i_msg]) {
 200                 case '\n':      /* new line, line feed (ASCII)  */
 201                         /* check if new mto needs to be created */
 202                         if (buffer->current_line == NULL) {
 203                                 rc = sclp_initialize_mto(buffer, 0);
 204                                 if (rc)
 205                                         return i_msg;
 206                         }
 207                         sclp_finalize_mto(buffer);
 208                         break;
 209                 case '\a':      /* bell, one for several times  */
 210                         /* set SCLP sound alarm bit in General Object */
 211                         if (buffer->current_line == NULL) {
 212                                 rc = sclp_initialize_mto(buffer,
 213                                                          buffer->columns);
 214                                 if (rc)
 215                                         return i_msg;
 216                         }
 217                         buffer->current_msg->mdb.go.general_msg_flags |=
 218                                 GNRLMSGFLGS_SNDALRM;
 219                         break;
 220                 case '\t':      /* horizontal tabulator  */
 221                         /* check if new mto needs to be created */
 222                         if (buffer->current_line == NULL) {
 223                                 rc = sclp_initialize_mto(buffer,
 224                                                          buffer->columns);
 225                                 if (rc)
 226                                         return i_msg;
 227                         }
 228                         /* "go to (next htab-boundary + 1, same line)" */
 229                         do {
 230                                 if (buffer->current_length >= buffer->columns)
 231                                         break;
 232                                 /* ok, add a blank */
 233                                 *buffer->current_line++ = 0x40;
 234                                 buffer->current_length++;
 235                         } while (buffer->current_length % buffer->htab);
 236                         break;
 237                 case '\f':      /* form feed  */
 238                 case '\v':      /* vertical tabulator  */
 239                         /* "go to (actual column, actual line + 1)" */
 240                         /* = new line, leading spaces */
 241                         if (buffer->current_line != NULL) {
 242                                 spaces = buffer->current_length;
 243                                 sclp_finalize_mto(buffer);
 244                                 rc = sclp_initialize_mto(buffer,
 245                                                          buffer->columns);
 246                                 if (rc)
 247                                         return i_msg;
 248                                 memset(buffer->current_line, 0x40, spaces);
 249                                 buffer->current_line += spaces;
 250                                 buffer->current_length = spaces;
 251                         } else {
 252                                 /* one an empty line this is the same as \n */
 253                                 rc = sclp_initialize_mto(buffer,
 254                                                          buffer->columns);
 255                                 if (rc)
 256                                         return i_msg;
 257                                 sclp_finalize_mto(buffer);
 258                         }
 259                         break;
 260                 case '\b':      /* backspace  */
 261                         /* "go to (actual column - 1, actual line)" */
 262                         /* decrement counter indicating position, */
 263                         /* do not remove last character */
 264                         if (buffer->current_line != NULL &&
 265                             buffer->current_length > 0) {
 266                                 buffer->current_length--;
 267                                 buffer->current_line--;
 268                         }
 269                         break;
 270                 case 0x00:      /* end of string  */
 271                         /* transfer current line to SCCB */
 272                         if (buffer->current_line != NULL)
 273                                 sclp_finalize_mto(buffer);
 274                         /* skip the rest of the message including the 0 byte */
 275                         i_msg = count - 1;
 276                         break;
 277                 default:        /* no escape character  */
 278                         /* do not output unprintable characters */
 279                         if (!isprint(msg[i_msg]))
 280                                 break;
 281                         /* check if new mto needs to be created */
 282                         if (buffer->current_line == NULL) {
 283                                 rc = sclp_initialize_mto(buffer,
 284                                                          buffer->columns);
 285                                 if (rc)
 286                                         return i_msg;
 287                         }
 288                         *buffer->current_line++ = sclp_ascebc(msg[i_msg]);
 289                         buffer->current_length++;
 290                         break;
 291                 }
 292                 /* check if current mto is full */
 293                 if (buffer->current_line != NULL &&
 294                     buffer->current_length >= buffer->columns)
 295                         sclp_finalize_mto(buffer);
 296         }
 297
 298         /* return number of processed characters */
 299         return i_msg;
 300 }
 301
 302 /*
 303  * Return the number of free bytes in the sccb
 304  */
 305 int
 306 sclp_buffer_space(struct sclp_buffer *buffer)
 307 {
 308         struct sccb_header *sccb;
 309         int count;
 310
 311         sccb = buffer->sccb;
 312         count = MAX_SCCB_ROOM - sccb->length;
 313         if (buffer->current_line != NULL)
 314                 count -= sizeof(struct msg_buf) + buffer->current_length;
 315         return count;
 316 }
 317
 318 /*
 319  * Return number of characters in buffer
 320  */
 321 unsigned int
 322 sclp_chars_in_buffer(struct sclp_buffer *buffer)
 323 {
 324         unsigned int count;
 325
 326         count = buffer->char_sum;
 327         if (buffer->current_line != NULL)
 328                 count += buffer->current_length;
 329         return count;
 330 }
 331
 332 /*
 333  * called by sclp_console_init and/or sclp_tty_init
 334  */
 335 int
 336 sclp_rw_init(void)
 337 {
 338         static int init_done = 0;
 339         int rc;
 340
 341         if (init_done)
 342                 return 0;
 343
 344         rc = sclp_register(&sclp_rw_event);
 345         if (rc == 0)
 346                 init_done = 1;
 347         return rc;
 348 }
 349
 350 #define SCLP_BUFFER_MAX_RETRY           1
 351
 352 /*
 353  * second half of Write Event Data-function that has to be done after
 354  * interruption indicating completion of Service Call.
 355  */
 356 static void
 357 sclp_writedata_callback(struct sclp_req *request, void *data)
 358 {
 359         int rc;
 360         struct sclp_buffer *buffer;
 361         struct sccb_header *sccb;
 362
 363         buffer = (struct sclp_buffer *) data;
 364         sccb = buffer->sccb;
 365
 366         if (request->status == SCLP_REQ_FAILED) {
 367                 if (buffer->callback != NULL)
 368                         buffer->callback(buffer, -EIO);
 369                 return;
 370         }
 371         /* check SCLP response code and choose suitable action  */
 372         switch (sccb->response_code) {
 373         case 0x0020 :
 374                 /* Normal completion, buffer processed, message(s) sent */
 375                 rc = 0;
 376                 break;
 377
 378         case 0x0340: /* Contained SCLP equipment check */
 379                 if (++buffer->retry_count > SCLP_BUFFER_MAX_RETRY) {
 380                         rc = -EIO;
 381                         break;
 382                 }
 383                 /* remove processed buffers and requeue rest */
 384                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 385                         /* not all buffers were processed */
 386                         sccb->response_code = 0x0000;
 387                         buffer->request.status = SCLP_REQ_FILLED;
 388                         rc = sclp_add_request(request);
 389                         if (rc == 0)
 390                                 return;
 391                 } else
 392                         rc = 0;
 393                 break;
 394
 395         case 0x0040: /* SCLP equipment check */
 396         case 0x05f0: /* Target resource in improper state */
 397                 if (++buffer->retry_count > SCLP_BUFFER_MAX_RETRY) {
 398                         rc = -EIO;
 399                         break;
 400                 }
 401                 /* retry request */
 402                 sccb->response_code = 0x0000;
 403                 buffer->request.status = SCLP_REQ_FILLED;
 404                 rc = sclp_add_request(request);
 405                 if (rc == 0)
 406                         return;
 407                 break;
 408         default:
 409                 if (sccb->response_code == 0x71f0)
 410                         rc = -ENOMEM;
 411                 else
 412                         rc = -EINVAL;
 413                 break;
 414         }
 415         if (buffer->callback != NULL)
 416                 buffer->callback(buffer, rc);
 417 }
 418
 419 /*
 420  * Setup the request structure in the struct sclp_buffer to do SCLP Write
 421  * Event Data and pass the request to the core SCLP loop. Return zero on
 422  * success, non-zero otherwise.
 423  */
 424 int
 425 sclp_emit_buffer(struct sclp_buffer *buffer,
 426                  void (*callback)(struct sclp_buffer *, int))
 427 {
 428         /* add current line if there is one */
 429         if (buffer->current_line != NULL)
 430                 sclp_finalize_mto(buffer);
 431
 432         /* Are there messages in the output buffer ? */
 433         if (buffer->messages == 0)
 434                 return -EIO;
 435
 436         buffer->request.command = SCLP_CMDW_WRITE_EVENT_DATA;
 437         buffer->request.status = SCLP_REQ_FILLED;
 438         buffer->request.callback = sclp_writedata_callback;
 439         buffer->request.callback_data = buffer;
 440         buffer->request.sccb = buffer->sccb;
 441         buffer->callback = callback;
 442         return sclp_add_request(&buffer->request);
 443 }