LXR linux/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 */
  24int 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}
  71