arch/powerpc/mm/vphn.c

   1 #include <asm/byteorder.h>
   2 #include "vphn.h"
   3
   4 /*
   5  * The associativity domain numbers are returned from the hypervisor as a
   6  * stream of mixed 16-bit and 32-bit fields. The stream is terminated by the
   7  * special value of "all ones" (aka. 0xffff) and its size may not exceed 48
   8  * bytes.
   9  *
  10  *    --- 16-bit fields -->
  11  *  _________________________
  12  *  |  0  |  1  |  2  |  3  |   be_packed[0]
  13  *  ------+-----+-----+------
  14  *  _________________________
  15  *  |  4  |  5  |  6  |  7  |   be_packed[1]
  16  *  -------------------------
  17  *            ...
  18  *  _________________________
  19  *  | 20  | 21  | 22  | 23  |   be_packed[5]
  20  *  -------------------------
  21  *
  22  * Convert to the sequence they would appear in the ibm,associativity property.
  23  */
  24 int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
  25 {
  26         __be64 be_packed[VPHN_REGISTER_COUNT];
  27         int i, nr_assoc_doms = 0;
  28         const __be16 *field = (const __be16 *) be_packed;
  29         u16 last = 0;
  30         bool is_32bit = false;
  31
  32 #define VPHN_FIELD_UNUSED       (0xffff)
  33 #define VPHN_FIELD_MSB          (0x8000)
  34 #define VPHN_FIELD_MASK         (~VPHN_FIELD_MSB)
  35
  36         /* Let's fix the values returned by plpar_hcall9() */
  37         for (i = 0; i < VPHN_REGISTER_COUNT; i++)
  38                 be_packed[i] = cpu_to_be64(packed[i]);
  39
  40         for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) {
  41                 u16 new = be16_to_cpup(field++);
  42
  43                 if (is_32bit) {
  44                         /* Let's concatenate the 16 bits of this field to the
  45                          * 15 lower bits of the previous field
  46                          */
  47                         unpacked[++nr_assoc_doms] =
  48                                 cpu_to_be32(last << 16 | new);
  49                         is_32bit = false;
  50                 } else if (new == VPHN_FIELD_UNUSED)
  51                         /* This is the list terminator */
  52                         break;
  53                 else if (new & VPHN_FIELD_MSB) {
  54                         /* Data is in the lower 15 bits of this field */
  55                         unpacked[++nr_assoc_doms] =
  56                                 cpu_to_be32(new & VPHN_FIELD_MASK);
  57                 } else {
  58                         /* Data is in the lower 15 bits of this field
  59                          * concatenated with the next 16 bit field
  60                          */
  61                         last = new;
  62                         is_32bit = true;
  63                 }
  64         }
  65
  66         /* The first cell contains the length of the property */
  67         unpacked[0] = cpu_to_be32(nr_assoc_doms);
  68
  69         return nr_assoc_doms;
  70 }