drivers/s390/cio/itcw.c

   1 /*
   2  *  Functions for incremental construction of fcx enabled I/O control blocks.
   3  *
   4  *    Copyright IBM Corp. 2008
   5  *    Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/types.h>
  10 #include <linux/string.h>
  11 #include <linux/errno.h>
  12 #include <linux/err.h>
  13 #include <linux/module.h>
  14 #include <asm/fcx.h>
  15 #include <asm/itcw.h>
  16
  17 /**
  18  * struct itcw - incremental tcw helper data type
  19  *
  20  * This structure serves as a handle for the incremental construction of a
  21  * tcw and associated tccb, tsb, data tidaw-list plus an optional interrogate
  22  * tcw and associated data. The data structures are contained inside a single
  23  * contiguous buffer provided by the user.
  24  *
  25  * The itcw construction functions take care of overall data integrity:
  26  * - reset unused fields to zero
  27  * - fill in required pointers
  28  * - ensure required alignment for data structures
  29  * - prevent data structures to cross 4k-byte boundary where required
  30  * - calculate tccb-related length fields
  31  * - optionally provide ready-made interrogate tcw and associated structures
  32  *
  33  * Restrictions apply to the itcws created with these construction functions:
  34  * - tida only supported for data address, not for tccb
  35  * - only contiguous tidaw-lists (no ttic)
  36  * - total number of bytes required per itcw may not exceed 4k bytes
  37  * - either read or write operation (may not work with r=0 and w=0)
  38  *
  39  * Example:
  40  * struct itcw *itcw;
  41  * void *buffer;
  42  * size_t size;
  43  *
  44  * size = itcw_calc_size(1, 2, 0);
  45  * buffer = kmalloc(size, GFP_KERNEL | GFP_DMA);
  46  * if (!buffer)
  47  *      return -ENOMEM;
  48  * itcw = itcw_init(buffer, size, ITCW_OP_READ, 1, 2, 0);
  49  * if (IS_ERR(itcw))
  50  *      return PTR_ER(itcw);
  51  * itcw_add_dcw(itcw, 0x2, 0, NULL, 0, 72);
  52  * itcw_add_tidaw(itcw, 0, 0x30000, 20);
  53  * itcw_add_tidaw(itcw, 0, 0x40000, 52);
  54  * itcw_finalize(itcw);
  55  *
  56  */
  57 struct itcw {
  58         struct tcw *tcw;
  59         struct tcw *intrg_tcw;
  60         int num_tidaws;
  61         int max_tidaws;
  62         int intrg_num_tidaws;
  63         int intrg_max_tidaws;
  64 };
  65
  66 /**
  67  * itcw_get_tcw - return pointer to tcw associated with the itcw
  68  * @itcw: address of the itcw
  69  *
  70  * Return pointer to the tcw associated with the itcw.
  71  */
  72 struct tcw *itcw_get_tcw(struct itcw *itcw)
  73 {
  74         return itcw->tcw;
  75 }
  76 EXPORT_SYMBOL(itcw_get_tcw);
  77
  78 /**
  79  * itcw_calc_size - return the size of an itcw with the given parameters
  80  * @intrg: if non-zero, add an interrogate tcw
  81  * @max_tidaws: maximum number of tidaws to be used for data addressing or zero
  82  * if no tida is to be used.
  83  * @intrg_max_tidaws: maximum number of tidaws to be used for data addressing
  84  * by the interrogate tcw, if specified
  85  *
  86  * Calculate and return the number of bytes required to hold an itcw with the
  87  * given parameters and assuming tccbs with maximum size.
  88  *
  89  * Note that the resulting size also contains bytes needed for alignment
  90  * padding as well as padding to ensure that data structures don't cross a
  91  * 4k-boundary where required.
  92  */
  93 size_t itcw_calc_size(int intrg, int max_tidaws, int intrg_max_tidaws)
  94 {
  95         size_t len;
  96         int cross_count;
  97
  98         /* Main data. */
  99         len = sizeof(struct itcw);
 100         len += /* TCW */ sizeof(struct tcw) + /* TCCB */ TCCB_MAX_SIZE +
 101                /* TSB */ sizeof(struct tsb) +
 102                /* TIDAL */ max_tidaws * sizeof(struct tidaw);
 103         /* Interrogate data. */
 104         if (intrg) {
 105                 len += /* TCW */ sizeof(struct tcw) + /* TCCB */ TCCB_MAX_SIZE +
 106                        /* TSB */ sizeof(struct tsb) +
 107                        /* TIDAL */ intrg_max_tidaws * sizeof(struct tidaw);
 108         }
 109
 110         /* Maximum required alignment padding. */
 111         len += /* Initial TCW */ 63 + /* Interrogate TCCB */ 7;
 112
 113         /* TIDAW lists may not cross a 4k boundary. To cross a
 114          * boundary we need to add a TTIC TIDAW. We need to reserve
 115          * one additional TIDAW for a TTIC that we may need to add due
 116          * to the placement of the data chunk in memory, and a further
 117          * TIDAW for each page boundary that the TIDAW list may cross
 118          * due to it's own size.
 119          */
 120         if (max_tidaws) {
 121                 cross_count = 1 + ((max_tidaws * sizeof(struct tidaw) - 1)
 122                                    >> PAGE_SHIFT);
 123                 len += cross_count * sizeof(struct tidaw);
 124         }
 125         if (intrg_max_tidaws) {
 126                 cross_count = 1 + ((intrg_max_tidaws * sizeof(struct tidaw) - 1)
 127                                    >> PAGE_SHIFT);
 128                 len += cross_count * sizeof(struct tidaw);
 129         }
 130         return len;
 131 }
 132 EXPORT_SYMBOL(itcw_calc_size);
 133
 134 #define CROSS4K(x, l)   (((x) & ~4095) != ((x + l) & ~4095))
 135
 136 static inline void *fit_chunk(addr_t *start, addr_t end, size_t len,
 137                               int align, int check_4k)
 138 {
 139         addr_t addr;
 140
 141         addr = ALIGN(*start, align);
 142         if (check_4k && CROSS4K(addr, len)) {
 143                 addr = ALIGN(addr, 4096);
 144                 addr = ALIGN(addr, align);
 145         }
 146         if (addr + len > end)
 147                 return ERR_PTR(-ENOSPC);
 148         *start = addr + len;
 149         return (void *) addr;
 150 }
 151
 152 /**
 153  * itcw_init - initialize incremental tcw data structure
 154  * @buffer: address of buffer to use for data structures
 155  * @size: number of bytes in buffer
 156  * @op: %ITCW_OP_READ for a read operation tcw, %ITCW_OP_WRITE for a write
 157  * operation tcw
 158  * @intrg: if non-zero, add and initialize an interrogate tcw
 159  * @max_tidaws: maximum number of tidaws to be used for data addressing or zero
 160  * if no tida is to be used.
 161  * @intrg_max_tidaws: maximum number of tidaws to be used for data addressing
 162  * by the interrogate tcw, if specified
 163  *
 164  * Prepare the specified buffer to be used as an incremental tcw, i.e. a
 165  * helper data structure that can be used to construct a valid tcw by
 166  * successive calls to other helper functions. Note: the buffer needs to be
 167  * located below the 2G address limit. The resulting tcw has the following
 168  * restrictions:
 169  *  - no tccb tidal
 170  *  - input/output tidal is contiguous (no ttic)
 171  *  - total data should not exceed 4k
 172  *  - tcw specifies either read or write operation
 173  *
 174  * On success, return pointer to the resulting incremental tcw data structure,
 175  * ERR_PTR otherwise.
 176  */
 177 struct itcw *itcw_init(void *buffer, size_t size, int op, int intrg,
 178                        int max_tidaws, int intrg_max_tidaws)
 179 {
 180         struct itcw *itcw;
 181         void *chunk;
 182         addr_t start;
 183         addr_t end;
 184         int cross_count;
 185
 186         /* Check for 2G limit. */
 187         start = (addr_t) buffer;
 188         end = start + size;
 189         if (end > (1 << 31))
 190                 return ERR_PTR(-EINVAL);
 191         memset(buffer, 0, size);
 192         /* ITCW. */
 193         chunk = fit_chunk(&start, end, sizeof(struct itcw), 1, 0);
 194         if (IS_ERR(chunk))
 195                 return chunk;
 196         itcw = chunk;
 197         /* allow for TTIC tidaws that may be needed to cross a page boundary */
 198         cross_count = 0;
 199         if (max_tidaws)
 200                 cross_count = 1 + ((max_tidaws * sizeof(struct tidaw) - 1)
 201                                    >> PAGE_SHIFT);
 202         itcw->max_tidaws = max_tidaws + cross_count;
 203         cross_count = 0;
 204         if (intrg_max_tidaws)
 205                 cross_count = 1 + ((intrg_max_tidaws * sizeof(struct tidaw) - 1)
 206                                    >> PAGE_SHIFT);
 207         itcw->intrg_max_tidaws = intrg_max_tidaws + cross_count;
 208         /* Main TCW. */
 209         chunk = fit_chunk(&start, end, sizeof(struct tcw), 64, 0);
 210         if (IS_ERR(chunk))
 211                 return chunk;
 212         itcw->tcw = chunk;
 213         tcw_init(itcw->tcw, (op == ITCW_OP_READ) ? 1 : 0,
 214                  (op == ITCW_OP_WRITE) ? 1 : 0);
 215         /* Interrogate TCW. */
 216         if (intrg) {
 217                 chunk = fit_chunk(&start, end, sizeof(struct tcw), 64, 0);
 218                 if (IS_ERR(chunk))
 219                         return chunk;
 220                 itcw->intrg_tcw = chunk;
 221                 tcw_init(itcw->intrg_tcw, 1, 0);
 222                 tcw_set_intrg(itcw->tcw, itcw->intrg_tcw);
 223         }
 224         /* Data TIDAL. */
 225         if (max_tidaws > 0) {
 226                 chunk = fit_chunk(&start, end, sizeof(struct tidaw) *
 227                                   itcw->max_tidaws, 16, 0);
 228                 if (IS_ERR(chunk))
 229                         return chunk;
 230                 tcw_set_data(itcw->tcw, chunk, 1);
 231         }
 232         /* Interrogate data TIDAL. */
 233         if (intrg && (intrg_max_tidaws > 0)) {
 234                 chunk = fit_chunk(&start, end, sizeof(struct tidaw) *
 235                                   itcw->intrg_max_tidaws, 16, 0);
 236                 if (IS_ERR(chunk))
 237                         return chunk;
 238                 tcw_set_data(itcw->intrg_tcw, chunk, 1);
 239         }
 240         /* TSB. */
 241         chunk = fit_chunk(&start, end, sizeof(struct tsb), 8, 0);
 242         if (IS_ERR(chunk))
 243                 return chunk;
 244         tsb_init(chunk);
 245         tcw_set_tsb(itcw->tcw, chunk);
 246         /* Interrogate TSB. */
 247         if (intrg) {
 248                 chunk = fit_chunk(&start, end, sizeof(struct tsb), 8, 0);
 249                 if (IS_ERR(chunk))
 250                         return chunk;
 251                 tsb_init(chunk);
 252                 tcw_set_tsb(itcw->intrg_tcw, chunk);
 253         }
 254         /* TCCB. */
 255         chunk = fit_chunk(&start, end, TCCB_MAX_SIZE, 8, 0);
 256         if (IS_ERR(chunk))
 257                 return chunk;
 258         tccb_init(chunk, TCCB_MAX_SIZE, TCCB_SAC_DEFAULT);
 259         tcw_set_tccb(itcw->tcw, chunk);
 260         /* Interrogate TCCB. */
 261         if (intrg) {
 262                 chunk = fit_chunk(&start, end, TCCB_MAX_SIZE, 8, 0);
 263                 if (IS_ERR(chunk))
 264                         return chunk;
 265                 tccb_init(chunk, TCCB_MAX_SIZE, TCCB_SAC_INTRG);
 266                 tcw_set_tccb(itcw->intrg_tcw, chunk);
 267                 tccb_add_dcw(chunk, TCCB_MAX_SIZE, DCW_CMD_INTRG, 0, NULL,
 268                              sizeof(struct dcw_intrg_data), 0);
 269                 tcw_finalize(itcw->intrg_tcw, 0);
 270         }
 271         return itcw;
 272 }
 273 EXPORT_SYMBOL(itcw_init);
 274
 275 /**
 276  * itcw_add_dcw - add a dcw to the itcw
 277  * @itcw: address of the itcw
 278  * @cmd: the dcw command
 279  * @flags: flags for the dcw
 280  * @cd: address of control data for this dcw or NULL if none is required
 281  * @cd_count: number of control data bytes for this dcw
 282  * @count: number of data bytes for this dcw
 283  *
 284  * Add a new dcw to the specified itcw by writing the dcw information specified
 285  * by @cmd, @flags, @cd, @cd_count and @count to the tca of the tccb. Return
 286  * a pointer to the newly added dcw on success or -%ENOSPC if the new dcw
 287  * would exceed the available space.
 288  *
 289  * Note: the tcal field of the tccb header will be updated to reflect added
 290  * content.
 291  */
 292 struct dcw *itcw_add_dcw(struct itcw *itcw, u8 cmd, u8 flags, void *cd,
 293                          u8 cd_count, u32 count)
 294 {
 295         return tccb_add_dcw(tcw_get_tccb(itcw->tcw), TCCB_MAX_SIZE, cmd,
 296                             flags, cd, cd_count, count);
 297 }
 298 EXPORT_SYMBOL(itcw_add_dcw);
 299
 300 /**
 301  * itcw_add_tidaw - add a tidaw to the itcw
 302  * @itcw: address of the itcw
 303  * @flags: flags for the new tidaw
 304  * @addr: address value for the new tidaw
 305  * @count: count value for the new tidaw
 306  *
 307  * Add a new tidaw to the input/output data tidaw-list of the specified itcw
 308  * (depending on the value of the r-flag and w-flag). Return a pointer to
 309  * the new tidaw on success or -%ENOSPC if the new tidaw would exceed the
 310  * available space.
 311  *
 312  * Note: TTIC tidaws are automatically added when needed, so explicitly calling
 313  * this interface with the TTIC flag is not supported. The last-tidaw flag
 314  * for the last tidaw in the list will be set by itcw_finalize.
 315  */
 316 struct tidaw *itcw_add_tidaw(struct itcw *itcw, u8 flags, void *addr, u32 count)
 317 {
 318         struct tidaw *following;
 319
 320         if (itcw->num_tidaws >= itcw->max_tidaws)
 321                 return ERR_PTR(-ENOSPC);
 322         /*
 323          * Is the tidaw, which follows the one we are about to fill, on the next
 324          * page? Then we have to insert a TTIC tidaw first, that points to the
 325          * tidaw on the new page.
 326          */
 327         following = ((struct tidaw *) tcw_get_data(itcw->tcw))
 328                 + itcw->num_tidaws + 1;
 329         if (itcw->num_tidaws && !((unsigned long) following & ~PAGE_MASK)) {
 330                 tcw_add_tidaw(itcw->tcw, itcw->num_tidaws++,
 331                               TIDAW_FLAGS_TTIC, following, 0);
 332                 if (itcw->num_tidaws >= itcw->max_tidaws)
 333                         return ERR_PTR(-ENOSPC);
 334         }
 335         return tcw_add_tidaw(itcw->tcw, itcw->num_tidaws++, flags, addr, count);
 336 }
 337 EXPORT_SYMBOL(itcw_add_tidaw);
 338
 339 /**
 340  * itcw_set_data - set data address and tida flag of the itcw
 341  * @itcw: address of the itcw
 342  * @addr: the data address
 343  * @use_tidal: zero of the data address specifies a contiguous block of data,
 344  * non-zero if it specifies a list if tidaws.
 345  *
 346  * Set the input/output data address of the itcw (depending on the value of the
 347  * r-flag and w-flag). If @use_tidal is non-zero, the corresponding tida flag
 348  * is set as well.
 349  */
 350 void itcw_set_data(struct itcw *itcw, void *addr, int use_tidal)
 351 {
 352         tcw_set_data(itcw->tcw, addr, use_tidal);
 353 }
 354 EXPORT_SYMBOL(itcw_set_data);
 355
 356 /**
 357  * itcw_finalize - calculate length and count fields of the itcw
 358  * @itcw: address of the itcw
 359  *
 360  * Calculate tcw input-/output-count and tccbl fields and add a tcat the tccb.
 361  * In case input- or output-tida is used, the tidaw-list must be stored in
 362  * continuous storage (no ttic). The tcal field in the tccb must be
 363  * up-to-date.
 364  */
 365 void itcw_finalize(struct itcw *itcw)
 366 {
 367         tcw_finalize(itcw->tcw, itcw->num_tidaws);
 368 }
 369 EXPORT_SYMBOL(itcw_finalize);