/*
 * iSeries hashtable management.
 *      Derived from pSeries_htab.c
 *
 * SMP scalability work:
 *    Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#include <asm/machdep.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/abs_addr.h>
#include <linux/spinlock.h>

#include "call_hpt.h"

static spinlock_t iSeries_hlocks[64] __cacheline_aligned_in_smp;

/*
 * Very primitive algorithm for picking up a lock
 */
static inline void iSeries_hlock(unsigned long slot)
{
        if (slot & 0x8)
                slot = ~slot;
        spin_lock(&iSeries_hlocks[(slot >> 4) & 0x3f]);
}

static inline void iSeries_hunlock(unsigned long slot)
{
        if (slot & 0x8)
                slot = ~slot;
        spin_unlock(&iSeries_hlocks[(slot >> 4) & 0x3f]);
}

static long iSeries_hpte_insert(unsigned long hpte_group, unsigned long va,
                         unsigned long pa, unsigned long rflags,
                         unsigned long vflags, int psize, int ssize)
{
        long slot;
        struct hash_pte lhpte;
        int secondary = 0;

        BUG_ON(psize != MMU_PAGE_4K);

        /*
         * The hypervisor tries both primary and secondary.
         * If we are being called to insert in the secondary,
         * it means we have already tried both primary and secondary,
         * so we return failure immediately.
         */
        if (vflags & HPTE_V_SECONDARY)
                return -1;

        iSeries_hlock(hpte_group);

        slot = HvCallHpt_findValid(&lhpte, va >> HW_PAGE_SHIFT);
        if (unlikely(lhpte.v & HPTE_V_VALID)) {
                if (vflags & HPTE_V_BOLTED) {
                        HvCallHpt_setSwBits(slot, 0x10, 0);
                        HvCallHpt_setPp(slot, PP_RWXX);
                        iSeries_hunlock(hpte_group);
                        if (slot < 0)
                                return 0x8 | (slot & 7);
                        else
                                return slot & 7;
                }
                BUG();
        }

        if (slot == -1) { /* No available entry found in either group */
                iSeries_hunlock(hpte_group);
                return -1;
        }

        if (slot < 0) {         /* MSB set means secondary group */
                vflags |= HPTE_V_SECONDARY;
                secondary = 1;
                slot &= 0x7fffffffffffffff;
        }


        lhpte.v = hpte_encode_v(va, MMU_PAGE_4K, MMU_SEGSIZE_256M) |
                vflags | HPTE_V_VALID;
        lhpte.r = hpte_encode_r(phys_to_abs(pa), MMU_PAGE_4K) | rflags;

        /* Now fill in the actual HPTE */
        HvCallHpt_addValidate(slot, secondary, &lhpte);

        iSeries_hunlock(hpte_group);

        return (secondary << 3) | (slot & 7);
}

static unsigned long iSeries_hpte_getword0(unsigned long slot)
{
        struct hash_pte hpte;

        HvCallHpt_get(&hpte, slot);
        return hpte.v;
}

static long iSeries_hpte_remove(unsigned long hpte_group)
{
        unsigned long slot_offset;
        int i;
        unsigned long hpte_v;

        /* Pick a random slot to start at */
        slot_offset = mftb() & 0x7;

        iSeries_hlock(hpte_group);

        for (i = 0; i < HPTES_PER_GROUP; i++) {
                hpte_v = iSeries_hpte_getword0(hpte_group + slot_offset);

                if (! (hpte_v & HPTE_V_BOLTED)) {
                        HvCallHpt_invalidateSetSwBitsGet(hpte_group +
                                                         slot_offset, 0, 0);
                        iSeries_hunlock(hpte_group);
                        return i;
                }

                slot_offset++;
                slot_offset &= 0x7;
        }

        iSeries_hunlock(hpte_group);

        return -1;
}

/*
 * The HyperVisor expects the "flags" argument in this form:
 *      bits  0..59 : reserved
 *      bit      60 : N
 *      bits 61..63 : PP2,PP1,PP0
 */
static long iSeries_hpte_updatepp(unsigned long slot, unsigned long newpp,
                        unsigned long va, int psize, int ssize, int local)
{
        struct hash_pte hpte;
        unsigned long want_v;

        iSeries_hlock(slot);

        HvCallHpt_get(&hpte, slot);
        want_v = hpte_encode_v(va, MMU_PAGE_4K, MMU_SEGSIZE_256M);

        if (HPTE_V_COMPARE(hpte.v, want_v) && (hpte.v & HPTE_V_VALID)) {
                /*
                 * Hypervisor expects bits as NPPP, which is
                 * different from how they are mapped in our PP.
                 */
                HvCallHpt_setPp(slot, (newpp & 0x3) | ((newpp & 0x4) << 1));
                iSeries_hunlock(slot);
                return 0;
        }
        iSeries_hunlock(slot);

        return -1;
}

/*
 * Functions used to find the PTE for a particular virtual address.
 * Only used during boot when bolting pages.
 *
 * Input : vpn      : virtual page number
 * Output: PTE index within the page table of the entry
 *         -1 on failure
 */
static long iSeries_hpte_find(unsigned long vpn)
{
        struct hash_pte hpte;
        long slot;

        /*
         * The HvCallHpt_findValid interface is as follows:
         * 0xffffffffffffffff : No entry found.
         * 0x00000000xxxxxxxx : Entry found in primary group, slot x
         * 0x80000000xxxxxxxx : Entry found in secondary group, slot x
         */
        slot = HvCallHpt_findValid(&hpte, vpn);
        if (hpte.v & HPTE_V_VALID) {
                if (slot < 0) {
                        slot &= 0x7fffffffffffffff;
                        slot = -slot;
                }
        } else
                slot = -1;
        return slot;
}

/*
 * Update the page protection bits. Intended to be used to create
 * guard pages for kernel data structures on pages which are bolted
 * in the HPT. Assumes pages being operated on will not be stolen.
 * Does not work on large pages.
 *
 * No need to lock here because we should be the only user.
 */
static void iSeries_hpte_updateboltedpp(unsigned long newpp, unsigned long ea,
                                        int psize, int ssize)
{
        unsigned long vsid,va,vpn;
        long slot;

        BUG_ON(psize != MMU_PAGE_4K);

        vsid = get_kernel_vsid(ea, MMU_SEGSIZE_256M);
        va = (vsid << 28) | (ea & 0x0fffffff);
        vpn = va >> HW_PAGE_SHIFT;
        slot = iSeries_hpte_find(vpn);
        if (slot == -1)
                panic("updateboltedpp: Could not find page to bolt\n");
        HvCallHpt_setPp(slot, newpp);
}

static void iSeries_hpte_invalidate(unsigned long slot, unsigned long va,
                                    int psize, int ssize, int local)
{
        unsigned long hpte_v;
        unsigned long avpn = va >> 23;
        unsigned long flags;

        local_irq_save(flags);

        iSeries_hlock(slot);

        hpte_v = iSeries_hpte_getword0(slot);

        if ((HPTE_V_AVPN_VAL(hpte_v) == avpn) && (hpte_v & HPTE_V_VALID))
                HvCallHpt_invalidateSetSwBitsGet(slot, 0, 0);

        iSeries_hunlock(slot);

        local_irq_restore(flags);
}

void __init hpte_init_iSeries(void)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(iSeries_hlocks); i++)
                spin_lock_init(&iSeries_hlocks[i]);

        ppc_md.hpte_invalidate  = iSeries_hpte_invalidate;
        ppc_md.hpte_updatepp    = iSeries_hpte_updatepp;
        ppc_md.hpte_updateboltedpp = iSeries_hpte_updateboltedpp;
        ppc_md.hpte_insert      = iSeries_hpte_insert;
        ppc_md.hpte_remove      = iSeries_hpte_remove;
}