drivers/s390/cio/itcw.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Functions for incremental construction of fcx enabled I/O control blocks.
   4  *
   5  *    Copyright IBM Corp. 2008
   6  *    Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/types.h>
  11 #include <linux/string.h>
  12 #include <linux/errno.h>
  13 #include <linux/err.h>
  14 #include <linux/module.h>
  15 #include <asm/fcx.h>
  16 #include <asm/itcw.h>
  17
  18 /**
  19  * struct itcw - incremental tcw helper data type
  20  *
  21  * This structure serves as a handle for the incremental construction of a
  22  * tcw and associated tccb, tsb, data tidaw-list plus an optional interrogate
  23  * tcw and associated data. The data structures are contained inside a single
  24  * contiguous buffer provided by the user.
  25  *
  26  * The itcw construction functions take care of overall data integrity:
  27  * - reset unused fields to zero
  28  * - fill in required pointers
  29  * - ensure required alignment for data structures
  30  * - prevent data structures to cross 4k-byte boundary where required
  31  * - calculate tccb-related length fields
  32  * - optionally provide ready-made interrogate tcw and associated structures
  33  *
  34  * Restrictions apply to the itcws created with these construction functions:
  35  * - tida only supported for data address, not for tccb
  36  * - only contiguous tidaw-lists (no ttic)
  37  * - total number of bytes required per itcw may not exceed 4k bytes
  38  * - either read or write operation (may not work with r=0 and w=0)
  39  *
  40  * Example:
  41  * struct itcw *itcw;
  42  * void *buffer;
  43  * size_t size;
  44  *
  45  * size = itcw_calc_size(1, 2, 0);
  46  * buffer = kmalloc(size, GFP_KERNEL | GFP_DMA);
  47  * if (!buffer)
  48  *      return -ENOMEM;
  49  * itcw = itcw_init(buffer, size, ITCW_OP_READ, 1, 2, 0);
  50  * if (IS_ERR(itcw))
  51  *      return PTR_ER(itcw);
  52  * itcw_add_dcw(itcw, 0x2, 0, NULL, 0, 72);
  53  * itcw_add_tidaw(itcw, 0, 0x30000, 20);
  54  * itcw_add_tidaw(itcw, 0, 0x40000, 52);
  55  * itcw_finalize(itcw);
  56  *
  57  */
  58 struct itcw {
  59         struct tcw *tcw;
  60         struct tcw *intrg_tcw;
  61         int num_tidaws;
  62         int max_tidaws;
  63         int intrg_num_tidaws;
  64         int intrg_max_tidaws;
  65 };
  66
  67 /**
  68  * itcw_get_tcw - return pointer to tcw associated with the itcw
  69  * @itcw: address of the itcw
  70  *
  71  * Return pointer to the tcw associated with the itcw.
  72  */
  73 struct tcw *itcw_get_tcw(struct itcw *itcw)
  74 {
  75         return itcw->tcw;
  76 }
  77 EXPORT_SYMBOL(itcw_get_tcw);
  78
  79 /**
  80  * itcw_calc_size - return the size of an itcw with the given parameters
  81  * @intrg: if non-zero, add an interrogate tcw
  82  * @max_tidaws: maximum number of tidaws to be used for data addressing or zero
  83  * if no tida is to be used.
  84  * @intrg_max_tidaws: maximum number of tidaws to be used for data addressing
  85  * by the interrogate tcw, if specified
  86  *
  87  * Calculate and return the number of bytes required to hold an itcw with the
  88  * given parameters and assuming tccbs with maximum size.
  89  *
  90  * Note that the resulting size also contains bytes needed for alignment
  91  * padding as well as padding to ensure that data structures don't cross a
  92  * 4k-boundary where required.
  93  */
  94 size_t itcw_calc_size(int intrg, int max_tidaws, int intrg_max_tidaws)
  95 {
  96         size_t len;
  97         int cross_count;
  98
  99         /* Main data. */
 100         len = sizeof(struct itcw);
 101         len += /* TCW */ sizeof(struct tcw) + /* TCCB */ TCCB_MAX_SIZE +
 102                /* TSB */ sizeof(struct tsb) +
 103                /* TIDAL */ max_tidaws * sizeof(struct tidaw);
 104         /* Interrogate data. */
 105         if (intrg) {
 106                 len += /* TCW */ sizeof(struct tcw) + /* TCCB */ TCCB_MAX_SIZE +
 107                        /* TSB */ sizeof(struct tsb) +
 108                        /* TIDAL */ intrg_max_tidaws * sizeof(struct tidaw);
 109         }
 110
 111         /* Maximum required alignment padding. */
 112         len += /* Initial TCW */ 63 + /* Interrogate TCCB */ 7;
 113
 114         /* TIDAW lists may not cross a 4k boundary. To cross a
 115          * boundary we need to add a TTIC TIDAW. We need to reserve
 116          * one additional TIDAW for a TTIC that we may need to add due
 117          * to the placement of the data chunk in memory, and a further
 118          * TIDAW for each page boundary that the TIDAW list may cross
 119          * due to it's own size.
 120          */
 121         if (max_tidaws) {
 122                 cross_count = 1 + ((max_tidaws * sizeof(struct tidaw) - 1)
 123                                    >> PAGE_SHIFT);
 124                 len += cross_count * sizeof(struct tidaw);
 125         }
 126         if (intrg_max_tidaws) {
 127                 cross_count = 1 + ((intrg_max_tidaws * sizeof(struct tidaw) - 1)
 128                                    >> PAGE_SHIFT);
 129                 len += cross_count * sizeof(struct tidaw);
 130         }
 131         return len;
 132 }
 133 EXPORT_SYMBOL(itcw_calc_size);
 134
 135 #define CROSS4K(x, l)   (((x) & ~4095) != ((x + l) & ~4095))
 136
 137 static inline void *fit_chunk(addr_t *start, addr_t end, size_t len,
 138                               int align, int check_4k)
 139 {
 140         addr_t addr;
 141
 142         addr = ALIGN(*start, align);
 143         if (check_4k && CROSS4K(addr, len)) {
 144                 addr = ALIGN(addr, 4096);
 145                 addr = ALIGN(addr, align);
 146         }
 147         if (addr + len > end)
 148                 return ERR_PTR(-ENOSPC);
 149         *start = addr + len;
 150         return (void *) addr;
 151 }
 152
 153 /**
 154  * itcw_init - initialize incremental tcw data structure
 155  * @buffer: address of buffer to use for data structures
 156  * @size: number of bytes in buffer
 157  * @op: %ITCW_OP_READ for a read operation tcw, %ITCW_OP_WRITE for a write
 158  * operation tcw
 159  * @intrg: if non-zero, add and initialize an interrogate tcw
 160  * @max_tidaws: maximum number of tidaws to be used for data addressing or zero
 161  * if no tida is to be used.
 162  * @intrg_max_tidaws: maximum number of tidaws to be used for data addressing
 163  * by the interrogate tcw, if specified
 164  *
 165  * Prepare the specified buffer to be used as an incremental tcw, i.e. a
 166  * helper data structure that can be used to construct a valid tcw by
 167  * successive calls to other helper functions. Note: the buffer needs to be
 168  * located below the 2G address limit. The resulting tcw has the following
 169  * restrictions:
 170  *  - no tccb tidal
 171  *  - input/output tidal is contiguous (no ttic)
 172  *  - total data should not exceed 4k
 173  *  - tcw specifies either read or write operation
 174  *
 175  * On success, return pointer to the resulting incremental tcw data structure,
 176  * ERR_PTR otherwise.
 177  */
 178 struct itcw *itcw_init(void *buffer, size_t size, int op, int intrg,
 179                        int max_tidaws, int intrg_max_tidaws)
 180 {
 181         struct itcw *itcw;
 182         void *chunk;
 183         addr_t start;
 184         addr_t end;
 185         int cross_count;
 186
 187         /* Check for 2G limit. */
 188         start = (addr_t) buffer;
 189         end = start + size;
 190         if (end > (1 << 31))
 191                 return ERR_PTR(-EINVAL);
 192         memset(buffer, 0, size);
 193         /* ITCW. */
 194         chunk = fit_chunk(&start, end, sizeof(struct itcw), 1, 0);
 195         if (IS_ERR(chunk))
 196                 return chunk;
 197         itcw = chunk;
 198         /* allow for TTIC tidaws that may be needed to cross a page boundary */
 199         cross_count = 0;
 200         if (max_tidaws)
 201                 cross_count = 1 + ((max_tidaws * sizeof(struct tidaw) - 1)
 202                                    >> PAGE_SHIFT);
 203         itcw->max_tidaws = max_tidaws + cross_count;
 204         cross_count = 0;
 205         if (intrg_max_tidaws)
 206                 cross_count = 1 + ((intrg_max_tidaws * sizeof(struct tidaw) - 1)
 207                                    >> PAGE_SHIFT);
 208         itcw->intrg_max_tidaws = intrg_max_tidaws + cross_count;
 209         /* Main TCW. */
 210         chunk = fit_chunk(&start, end, sizeof(struct tcw), 64, 0);
 211         if (IS_ERR(chunk))
 212                 return chunk;
 213         itcw->tcw = chunk;
 214         tcw_init(itcw->tcw, (op == ITCW_OP_READ) ? 1 : 0,
 215                  (op == ITCW_OP_WRITE) ? 1 : 0);
 216         /* Interrogate TCW. */
 217         if (intrg) {
 218                 chunk = fit_chunk(&start, end, sizeof(struct tcw), 64, 0);
 219                 if (IS_ERR(chunk))
 220                         return chunk;
 221                 itcw->intrg_tcw = chunk;
 222                 tcw_init(itcw->intrg_tcw, 1, 0);
 223                 tcw_set_intrg(itcw->tcw, itcw->intrg_tcw);
 224         }
 225         /* Data TIDAL. */
 226         if (max_tidaws > 0) {
 227                 chunk = fit_chunk(&start, end, sizeof(struct tidaw) *
 228                                   itcw->max_tidaws, 16, 0);
 229                 if (IS_ERR(chunk))
 230                         return chunk;
 231                 tcw_set_data(itcw->tcw, chunk, 1);
 232         }
 233         /* Interrogate data TIDAL. */
 234         if (intrg && (intrg_max_tidaws > 0)) {
 235                 chunk = fit_chunk(&start, end, sizeof(struct tidaw) *
 236                                   itcw->intrg_max_tidaws, 16, 0);
 237                 if (IS_ERR(chunk))
 238                         return chunk;
 239                 tcw_set_data(itcw->intrg_tcw, chunk, 1);
 240         }
 241         /* TSB. */
 242         chunk = fit_chunk(&start, end, sizeof(struct tsb), 8, 0);
 243         if (IS_ERR(chunk))
 244                 return chunk;
 245         tsb_init(chunk);
 246         tcw_set_tsb(itcw->tcw, chunk);
 247         /* Interrogate TSB. */
 248         if (intrg) {
 249                 chunk = fit_chunk(&start, end, sizeof(struct tsb), 8, 0);
 250                 if (IS_ERR(chunk))
 251                         return chunk;
 252                 tsb_init(chunk);
 253                 tcw_set_tsb(itcw->intrg_tcw, chunk);
 254         }
 255         /* TCCB. */
 256         chunk = fit_chunk(&start, end, TCCB_MAX_SIZE, 8, 0);
 257         if (IS_ERR(chunk))
 258                 return chunk;
 259         tccb_init(chunk, TCCB_MAX_SIZE, TCCB_SAC_DEFAULT);
 260         tcw_set_tccb(itcw->tcw, chunk);
 261         /* Interrogate TCCB. */
 262         if (intrg) {
 263                 chunk = fit_chunk(&start, end, TCCB_MAX_SIZE, 8, 0);
 264                 if (IS_ERR(chunk))
 265                         return chunk;
 266                 tccb_init(chunk, TCCB_MAX_SIZE, TCCB_SAC_INTRG);
 267                 tcw_set_tccb(itcw->intrg_tcw, chunk);
 268                 tccb_add_dcw(chunk, TCCB_MAX_SIZE, DCW_CMD_INTRG, 0, NULL,
 269                              sizeof(struct dcw_intrg_data), 0);
 270                 tcw_finalize(itcw->intrg_tcw, 0);
 271         }
 272         return itcw;
 273 }
 274 EXPORT_SYMBOL(itcw_init);
 275
 276 /**
 277  * itcw_add_dcw - add a dcw to the itcw
 278  * @itcw: address of the itcw
 279  * @cmd: the dcw command
 280  * @flags: flags for the dcw
 281  * @cd: address of control data for this dcw or NULL if none is required
 282  * @cd_count: number of control data bytes for this dcw
 283  * @count: number of data bytes for this dcw
 284  *
 285  * Add a new dcw to the specified itcw by writing the dcw information specified
 286  * by @cmd, @flags, @cd, @cd_count and @count to the tca of the tccb. Return
 287  * a pointer to the newly added dcw on success or -%ENOSPC if the new dcw
 288  * would exceed the available space.
 289  *
 290  * Note: the tcal field of the tccb header will be updated to reflect added
 291  * content.
 292  */
 293 struct dcw *itcw_add_dcw(struct itcw *itcw, u8 cmd, u8 flags, void *cd,
 294                          u8 cd_count, u32 count)
 295 {
 296         return tccb_add_dcw(tcw_get_tccb(itcw->tcw), TCCB_MAX_SIZE, cmd,
 297                             flags, cd, cd_count, count);
 298 }
 299 EXPORT_SYMBOL(itcw_add_dcw);
 300
 301 /**
 302  * itcw_add_tidaw - add a tidaw to the itcw
 303  * @itcw: address of the itcw
 304  * @flags: flags for the new tidaw
 305  * @addr: address value for the new tidaw
 306  * @count: count value for the new tidaw
 307  *
 308  * Add a new tidaw to the input/output data tidaw-list of the specified itcw
 309  * (depending on the value of the r-flag and w-flag). Return a pointer to
 310  * the new tidaw on success or -%ENOSPC if the new tidaw would exceed the
 311  * available space.
 312  *
 313  * Note: TTIC tidaws are automatically added when needed, so explicitly calling
 314  * this interface with the TTIC flag is not supported. The last-tidaw flag
 315  * for the last tidaw in the list will be set by itcw_finalize.
 316  */
 317 struct tidaw *itcw_add_tidaw(struct itcw *itcw, u8 flags, void *addr, u32 count)
 318 {
 319         struct tidaw *following;
 320
 321         if (itcw->num_tidaws >= itcw->max_tidaws)
 322                 return ERR_PTR(-ENOSPC);
 323         /*
 324          * Is the tidaw, which follows the one we are about to fill, on the next
 325          * page? Then we have to insert a TTIC tidaw first, that points to the
 326          * tidaw on the new page.
 327          */
 328         following = ((struct tidaw *) tcw_get_data(itcw->tcw))
 329                 + itcw->num_tidaws + 1;
 330         if (itcw->num_tidaws && !((unsigned long) following & ~PAGE_MASK)) {
 331                 tcw_add_tidaw(itcw->tcw, itcw->num_tidaws++,
 332                               TIDAW_FLAGS_TTIC, following, 0);
 333                 if (itcw->num_tidaws >= itcw->max_tidaws)
 334                         return ERR_PTR(-ENOSPC);
 335         }
 336         return tcw_add_tidaw(itcw->tcw, itcw->num_tidaws++, flags, addr, count);
 337 }
 338 EXPORT_SYMBOL(itcw_add_tidaw);
 339
 340 /**
 341  * itcw_set_data - set data address and tida flag of the itcw
 342  * @itcw: address of the itcw
 343  * @addr: the data address
 344  * @use_tidal: zero of the data address specifies a contiguous block of data,
 345  * non-zero if it specifies a list if tidaws.
 346  *
 347  * Set the input/output data address of the itcw (depending on the value of the
 348  * r-flag and w-flag). If @use_tidal is non-zero, the corresponding tida flag
 349  * is set as well.
 350  */
 351 void itcw_set_data(struct itcw *itcw, void *addr, int use_tidal)
 352 {
 353         tcw_set_data(itcw->tcw, addr, use_tidal);
 354 }
 355 EXPORT_SYMBOL(itcw_set_data);
 356
 357 /**
 358  * itcw_finalize - calculate length and count fields of the itcw
 359  * @itcw: address of the itcw
 360  *
 361  * Calculate tcw input-/output-count and tccbl fields and add a tcat the tccb.
 362  * In case input- or output-tida is used, the tidaw-list must be stored in
 363  * continuous storage (no ttic). The tcal field in the tccb must be
 364  * up-to-date.
 365  */
 366 void itcw_finalize(struct itcw *itcw)
 367 {
 368         tcw_finalize(itcw->tcw, itcw->num_tidaws);
 369 }
 370 EXPORT_SYMBOL(itcw_finalize);