/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
 * Copyright (C) 1997, 1998, 1999, 2000 Ralf Baechle ralf@gnu.org
 * Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 2002 MIPS Technologies, Inc.  All rights reserved.
 */
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/module.h>

#include <asm/cpu.h>
#include <asm/cpu-type.h>
#include <asm/bootinfo.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/tlbmisc.h>

extern void build_tlb_refill_handler(void);

/*
 * Make sure all entries differ.  If they're not different
 * MIPS32 will take revenge ...
 */
#define UNIQUE_ENTRYHI(idx) (CKSEG0 + ((idx) << (PAGE_SHIFT + 1)))

/* Atomicity and interruptability */
#ifdef CONFIG_MIPS_MT_SMTC

#include <asm/smtc.h>
#include <asm/mipsmtregs.h>

#define ENTER_CRITICAL(flags) \
        { \
        unsigned int mvpflags; \
        local_irq_save(flags);\
        mvpflags = dvpe()
#define EXIT_CRITICAL(flags) \
        evpe(mvpflags); \
        local_irq_restore(flags); \
        }
#else

#define ENTER_CRITICAL(flags) local_irq_save(flags)
#define EXIT_CRITICAL(flags) local_irq_restore(flags)

#endif /* CONFIG_MIPS_MT_SMTC */

#if defined(CONFIG_CPU_LOONGSON2)
/*
 * LOONGSON2 has a 4 entry itlb which is a subset of dtlb,
 * unfortrunately, itlb is not totally transparent to software.
 */
#define FLUSH_ITLB write_c0_diag(4);

#define FLUSH_ITLB_VM(vma) { if ((vma)->vm_flags & VM_EXEC)  write_c0_diag(4); }

#else

#define FLUSH_ITLB
#define FLUSH_ITLB_VM(vma)

#endif

void local_flush_tlb_all(void)
{
        unsigned long flags;
        unsigned long old_ctx;
        int entry;

        ENTER_CRITICAL(flags);
        /* Save old context and create impossible VPN2 value */
        old_ctx = read_c0_entryhi();
        write_c0_entrylo0(0);
        write_c0_entrylo1(0);

        entry = read_c0_wired();

        /* Blast 'em all away. */
        while (entry < current_cpu_data.tlbsize) {
                /* Make sure all entries differ. */
                write_c0_entryhi(UNIQUE_ENTRYHI(entry));
                write_c0_index(entry);
                mtc0_tlbw_hazard();
                tlb_write_indexed();
                entry++;
        }
        tlbw_use_hazard();
        write_c0_entryhi(old_ctx);
        FLUSH_ITLB;
        EXIT_CRITICAL(flags);
}
EXPORT_SYMBOL(local_flush_tlb_all);

/* All entries common to a mm share an asid.  To effectively flush
   these entries, we just bump the asid. */
void local_flush_tlb_mm(struct mm_struct *mm)
{
        int cpu;

        preempt_disable();

        cpu = smp_processor_id();

        if (cpu_context(cpu, mm) != 0) {
                drop_mmu_context(mm, cpu);
        }

        preempt_enable();
}

void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
        unsigned long end)
{
        struct mm_struct *mm = vma->vm_mm;
        int cpu = smp_processor_id();

        if (cpu_context(cpu, mm) != 0) {
                unsigned long size, flags;

                ENTER_CRITICAL(flags);
                start = round_down(start, PAGE_SIZE << 1);
                end = round_up(end, PAGE_SIZE << 1);
                size = (end - start) >> (PAGE_SHIFT + 1);
                if (size <= current_cpu_data.tlbsize/2) {
                        int oldpid = read_c0_entryhi();
                        int newpid = cpu_asid(cpu, mm);

                        while (start < end) {
                                int idx;

                                write_c0_entryhi(start | newpid);
                                start += (PAGE_SIZE << 1);
                                mtc0_tlbw_hazard();
                                tlb_probe();
                                tlb_probe_hazard();
                                idx = read_c0_index();
                                write_c0_entrylo0(0);
                                write_c0_entrylo1(0);
                                if (idx < 0)
                                        continue;
                                /* Make sure all entries differ. */
                                write_c0_entryhi(UNIQUE_ENTRYHI(idx));
                                mtc0_tlbw_hazard();
                                tlb_write_indexed();
                        }
                        tlbw_use_hazard();
                        write_c0_entryhi(oldpid);
                } else {
                        drop_mmu_context(mm, cpu);
                }
                FLUSH_ITLB;
                EXIT_CRITICAL(flags);
        }
}

void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
        unsigned long size, flags;

        ENTER_CRITICAL(flags);
        size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
        size = (size + 1) >> 1;
        if (size <= current_cpu_data.tlbsize / 2) {
                int pid = read_c0_entryhi();

                start &= (PAGE_MASK << 1);
                end += ((PAGE_SIZE << 1) - 1);
                end &= (PAGE_MASK << 1);

                while (start < end) {
                        int idx;

                        write_c0_entryhi(start);
                        start += (PAGE_SIZE << 1);
                        mtc0_tlbw_hazard();
                        tlb_probe();
                        tlb_probe_hazard();
                        idx = read_c0_index();
                        write_c0_entrylo0(0);
                        write_c0_entrylo1(0);
                        if (idx < 0)
                                continue;
                        /* Make sure all entries differ. */
                        write_c0_entryhi(UNIQUE_ENTRYHI(idx));
                        mtc0_tlbw_hazard();
                        tlb_write_indexed();
                }
                tlbw_use_hazard();
                write_c0_entryhi(pid);
        } else {
                local_flush_tlb_all();
        }
        FLUSH_ITLB;
        EXIT_CRITICAL(flags);
}

void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
        int cpu = smp_processor_id();

        if (cpu_context(cpu, vma->vm_mm) != 0) {
                unsigned long flags;
                int oldpid, newpid, idx;

                newpid = cpu_asid(cpu, vma->vm_mm);
                page &= (PAGE_MASK << 1);
                ENTER_CRITICAL(flags);
                oldpid = read_c0_entryhi();
                write_c0_entryhi(page | newpid);
                mtc0_tlbw_hazard();
                tlb_probe();
                tlb_probe_hazard();
                idx = read_c0_index();
                write_c0_entrylo0(0);
                write_c0_entrylo1(0);
                if (idx < 0)
                        goto finish;
                /* Make sure all entries differ. */
                write_c0_entryhi(UNIQUE_ENTRYHI(idx));
                mtc0_tlbw_hazard();
                tlb_write_indexed();
                tlbw_use_hazard();

        finish:
                write_c0_entryhi(oldpid);
                FLUSH_ITLB_VM(vma);
                EXIT_CRITICAL(flags);
        }
}

/*
 * This one is only used for pages with the global bit set so we don't care
 * much about the ASID.
 */
void local_flush_tlb_one(unsigned long page)
{
        unsigned long flags;
        int oldpid, idx;

        ENTER_CRITICAL(flags);
        oldpid = read_c0_entryhi();
        page &= (PAGE_MASK << 1);
        write_c0_entryhi(page);
        mtc0_tlbw_hazard();
        tlb_probe();
        tlb_probe_hazard();
        idx = read_c0_index();
        write_c0_entrylo0(0);
        write_c0_entrylo1(0);
        if (idx >= 0) {
                /* Make sure all entries differ. */
                write_c0_entryhi(UNIQUE_ENTRYHI(idx));
                mtc0_tlbw_hazard();
                tlb_write_indexed();
                tlbw_use_hazard();
        }
        write_c0_entryhi(oldpid);
        FLUSH_ITLB;
        EXIT_CRITICAL(flags);
}

/*
 * We will need multiple versions of update_mmu_cache(), one that just
 * updates the TLB with the new pte(s), and another which also checks
 * for the R4k "end of page" hardware bug and does the needy.
 */
void __update_tlb(struct vm_area_struct * vma, unsigned long address, pte_t pte)
{
        unsigned long flags;
        pgd_t *pgdp;
        pud_t *pudp;
        pmd_t *pmdp;
        pte_t *ptep;
        int idx, pid;

        /*
         * Handle debugger faulting in for debugee.
         */
        if (current->active_mm != vma->vm_mm)
                return;

        ENTER_CRITICAL(flags);

        pid = read_c0_entryhi() & ASID_MASK;
        address &= (PAGE_MASK << 1);
        write_c0_entryhi(address | pid);
        pgdp = pgd_offset(vma->vm_mm, address);
        mtc0_tlbw_hazard();
        tlb_probe();
        tlb_probe_hazard();
        pudp = pud_offset(pgdp, address);
        pmdp = pmd_offset(pudp, address);
        idx = read_c0_index();
#ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
        /* this could be a huge page  */
        if (pmd_huge(*pmdp)) {
                unsigned long lo;
                write_c0_pagemask(PM_HUGE_MASK);
                ptep = (pte_t *)pmdp;
                lo = pte_to_entrylo(pte_val(*ptep));
                write_c0_entrylo0(lo);
                write_c0_entrylo1(lo + (HPAGE_SIZE >> 7));

                mtc0_tlbw_hazard();
                if (idx < 0)
                        tlb_write_random();
                else
                        tlb_write_indexed();
                tlbw_use_hazard();
                write_c0_pagemask(PM_DEFAULT_MASK);
        } else
#endif
        {
                ptep = pte_offset_map(pmdp, address);

#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
                write_c0_entrylo0(ptep->pte_high);
                ptep++;
                write_c0_entrylo1(ptep->pte_high);
#else
                write_c0_entrylo0(pte_to_entrylo(pte_val(*ptep++)));
                write_c0_entrylo1(pte_to_entrylo(pte_val(*ptep)));
#endif
                mtc0_tlbw_hazard();
                if (idx < 0)
                        tlb_write_random();
                else
                        tlb_write_indexed();
        }
        tlbw_use_hazard();
        FLUSH_ITLB_VM(vma);
        EXIT_CRITICAL(flags);
}

void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
                     unsigned long entryhi, unsigned long pagemask)
{
        unsigned long flags;
        unsigned long wired;
        unsigned long old_pagemask;
        unsigned long old_ctx;

        ENTER_CRITICAL(flags);
        /* Save old context and create impossible VPN2 value */
        old_ctx = read_c0_entryhi();
        old_pagemask = read_c0_pagemask();
        wired = read_c0_wired();
        write_c0_wired(wired + 1);
        write_c0_index(wired);
        tlbw_use_hazard();      /* What is the hazard here? */
        write_c0_pagemask(pagemask);
        write_c0_entryhi(entryhi);
        write_c0_entrylo0(entrylo0);
        write_c0_entrylo1(entrylo1);
        mtc0_tlbw_hazard();
        tlb_write_indexed();
        tlbw_use_hazard();

        write_c0_entryhi(old_ctx);
        tlbw_use_hazard();      /* What is the hazard here? */
        write_c0_pagemask(old_pagemask);
        local_flush_tlb_all();
        EXIT_CRITICAL(flags);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

int __init has_transparent_hugepage(void)
{
        unsigned int mask;
        unsigned long flags;

        ENTER_CRITICAL(flags);
        write_c0_pagemask(PM_HUGE_MASK);
        back_to_back_c0_hazard();
        mask = read_c0_pagemask();
        write_c0_pagemask(PM_DEFAULT_MASK);

        EXIT_CRITICAL(flags);

        return mask == PM_HUGE_MASK;
}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE  */

static int ntlb;
static int __init set_ntlb(char *str)
{
        get_option(&str, &ntlb);
        return 1;
}

__setup("ntlb=", set_ntlb);

void tlb_init(void)
{
        /*
         * You should never change this register:
         *   - On R4600 1.7 the tlbp never hits for pages smaller than
         *     the value in the c0_pagemask register.
         *   - The entire mm handling assumes the c0_pagemask register to
         *     be set to fixed-size pages.
         */
        write_c0_pagemask(PM_DEFAULT_MASK);
        write_c0_wired(0);
        if (current_cpu_type() == CPU_R10000 ||
            current_cpu_type() == CPU_R12000 ||
            current_cpu_type() == CPU_R14000)
                write_c0_framemask(0);

        if (cpu_has_rixi) {
                /*
                 * Enable the no read, no exec bits, and enable large virtual
                 * address.
                 */
                u32 pg = PG_RIE | PG_XIE;
#ifdef CONFIG_64BIT
                pg |= PG_ELPA;
#endif
                write_c0_pagegrain(pg);
        }

        /* From this point on the ARC firmware is dead.  */
        local_flush_tlb_all();

        /* Did I tell you that ARC SUCKS?  */

        if (ntlb) {
                if (ntlb > 1 && ntlb <= current_cpu_data.tlbsize) {
                        int wired = current_cpu_data.tlbsize - ntlb;
                        write_c0_wired(wired);
                        write_c0_index(wired-1);
                        printk("Restricting TLB to %d entries\n", ntlb);
                } else
                        printk("Ignoring invalid argument ntlb=%d\n", ntlb);
        }

        build_tlb_refill_handler();
}