// SPDX-License-Identifier: GPL-2.0
#include <asm/byteorder.h>
#include <asm/vphn.h>

/*
 * The associativity domain numbers are returned from the hypervisor as a
 * stream of mixed 16-bit and 32-bit fields. The stream is terminated by the
 * special value of "all ones" (aka. 0xffff) and its size may not exceed 48
 * bytes.
 *
 *    --- 16-bit fields -->
 *  _________________________
 *  |  0  |  1  |  2  |  3  |   be_packed[0]
 *  ------+-----+-----+------
 *  _________________________
 *  |  4  |  5  |  6  |  7  |   be_packed[1]
 *  -------------------------
 *            ...
 *  _________________________
 *  | 20  | 21  | 22  | 23  |   be_packed[5]
 *  -------------------------
 *
 * Convert to the sequence they would appear in the ibm,associativity property.
 */
static int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
{
        __be64 be_packed[VPHN_REGISTER_COUNT];
        int i, nr_assoc_doms = 0;
        const __be16 *field = (const __be16 *) be_packed;
        u16 last = 0;
        bool is_32bit = false;

#define VPHN_FIELD_UNUSED       (0xffff)
#define VPHN_FIELD_MSB          (0x8000)
#define VPHN_FIELD_MASK         (~VPHN_FIELD_MSB)

        /* Let's fix the values returned by plpar_hcall9() */
        for (i = 0; i < VPHN_REGISTER_COUNT; i++)
                be_packed[i] = cpu_to_be64(packed[i]);

        for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) {
                u16 new = be16_to_cpup(field++);

                if (is_32bit) {
                        /*
                         * Let's concatenate the 16 bits of this field to the
                         * 15 lower bits of the previous field
                         */
                        unpacked[++nr_assoc_doms] =
                                cpu_to_be32(last << 16 | new);
                        is_32bit = false;
                } else if (new == VPHN_FIELD_UNUSED)
                        /* This is the list terminator */
                        break;
                else if (new & VPHN_FIELD_MSB) {
                        /* Data is in the lower 15 bits of this field */
                        unpacked[++nr_assoc_doms] =
                                cpu_to_be32(new & VPHN_FIELD_MASK);
                } else {
                        /*
                         * Data is in the lower 15 bits of this field
                         * concatenated with the next 16 bit field
                         */
                        last = new;
                        is_32bit = true;
                }
        }

        /* The first cell contains the length of the property */
        unpacked[0] = cpu_to_be32(nr_assoc_doms);

        return nr_assoc_doms;
}

/* NOTE: This file is included by a selftest and built in userspace. */
#ifdef __KERNEL__
#include <asm/hvcall.h>

long hcall_vphn(unsigned long cpu, u64 flags, __be32 *associativity)
{
        long rc;
        long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};

        rc = plpar_hcall9(H_HOME_NODE_ASSOCIATIVITY, retbuf, flags, cpu);
        if (rc == H_SUCCESS)
                vphn_unpack_associativity(retbuf, associativity);

        return rc;
}
#endif