LXR linux/arch/powerpc/mm/vphn.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include <asm/byteorder.h>
   3#include "vphn.h"
   4
   5/*
   6 * The associativity domain numbers are returned from the hypervisor as a
   7 * stream of mixed 16-bit and 32-bit fields. The stream is terminated by the
   8 * special value of "all ones" (aka. 0xffff) and its size may not exceed 48
   9 * bytes.
  10 *
  11 *    --- 16-bit fields -->
  12 *  _________________________
  13 *  |  0  |  1  |  2  |  3  |   be_packed[0]
  14 *  ------+-----+-----+------
  15 *  _________________________
  16 *  |  4  |  5  |  6  |  7  |   be_packed[1]
  17 *  -------------------------
  18 *            ...
  19 *  _________________________
  20 *  | 20  | 21  | 22  | 23  |   be_packed[5]
  21 *  -------------------------
  22 *
  23 * Convert to the sequence they would appear in the ibm,associativity property.
  24 */
  25int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
  26{
  27        __be64 be_packed[VPHN_REGISTER_COUNT];
  28        int i, nr_assoc_doms = 0;
  29        const __be16 *field = (const __be16 *) be_packed;
  30        u16 last = 0;
  31        bool is_32bit = false;
  32
  33#define VPHN_FIELD_UNUSED       (0xffff)
  34#define VPHN_FIELD_MSB          (0x8000)
  35#define VPHN_FIELD_MASK         (~VPHN_FIELD_MSB)
  36
  37        /* Let's fix the values returned by plpar_hcall9() */
  38        for (i = 0; i < VPHN_REGISTER_COUNT; i++)
  39                be_packed[i] = cpu_to_be64(packed[i]);
  40
  41        for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) {
  42                u16 new = be16_to_cpup(field++);
  43
  44                if (is_32bit) {
  45                        /* Let's concatenate the 16 bits of this field to the
  46                         * 15 lower bits of the previous field
  47                         */
  48                        unpacked[++nr_assoc_doms] =
  49                                cpu_to_be32(last << 16 | new);
  50                        is_32bit = false;
  51                } else if (new == VPHN_FIELD_UNUSED)
  52                        /* This is the list terminator */
  53                        break;
  54                else if (new & VPHN_FIELD_MSB) {
  55                        /* Data is in the lower 15 bits of this field */
  56                        unpacked[++nr_assoc_doms] =
  57                                cpu_to_be32(new & VPHN_FIELD_MASK);
  58                } else {
  59                        /* Data is in the lower 15 bits of this field
  60                         * concatenated with the next 16 bit field
  61                         */
  62                        last = new;
  63                        is_32bit = true;
  64                }
  65        }
  66
  67        /* The first cell contains the length of the property */
  68        unpacked[0] = cpu_to_be32(nr_assoc_doms);
  69
  70        return nr_assoc_doms;
  71}
  72