/*
 * This file contains the routines for TLB flushing.
 * On machines where the MMU does not use a hash table to store virtual to
 * physical translations (ie, SW loaded TLBs or Book3E compilant processors,
 * this does -not- include 603 however which shares the implementation with
 * hash based processors)
 *
 *  -- BenH
 *
 * Copyright 2008,2009 Ben Herrenschmidt <benh@kernel.crashing.org>
 *                     IBM Corp.
 *
 *  Derived from arch/ppc/mm/init.c:
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
 *    Copyright (C) 1996 Paul Mackerras
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  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 <linux/kernel.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/preempt.h>
#include <linux/spinlock.h>
#include <linux/lmb.h>

#include <asm/tlbflush.h>
#include <asm/tlb.h>
#include <asm/code-patching.h>

#include "mmu_decl.h"

#ifdef CONFIG_PPC_BOOK3E
struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT] = {
        [MMU_PAGE_4K] = {
                .shift  = 12,
                .enc    = BOOK3E_PAGESZ_4K,
        },
        [MMU_PAGE_16K] = {
                .shift  = 14,
                .enc    = BOOK3E_PAGESZ_16K,
        },
        [MMU_PAGE_64K] = {
                .shift  = 16,
                .enc    = BOOK3E_PAGESZ_64K,
        },
        [MMU_PAGE_1M] = {
                .shift  = 20,
                .enc    = BOOK3E_PAGESZ_1M,
        },
        [MMU_PAGE_16M] = {
                .shift  = 24,
                .enc    = BOOK3E_PAGESZ_16M,
        },
        [MMU_PAGE_256M] = {
                .shift  = 28,
                .enc    = BOOK3E_PAGESZ_256M,
        },
        [MMU_PAGE_1G] = {
                .shift  = 30,
                .enc    = BOOK3E_PAGESZ_1GB,
        },
};
static inline int mmu_get_tsize(int psize)
{
        return mmu_psize_defs[psize].enc;
}
#else
static inline int mmu_get_tsize(int psize)
{
        /* This isn't used on !Book3E for now */
        return 0;
}
#endif

/* The variables below are currently only used on 64-bit Book3E
 * though this will probably be made common with other nohash
 * implementations at some point
 */
#ifdef CONFIG_PPC64

int mmu_linear_psize;           /* Page size used for the linear mapping */
int mmu_pte_psize;              /* Page size used for PTE pages */
int mmu_vmemmap_psize;          /* Page size used for the virtual mem map */
int book3e_htw_enabled;         /* Is HW tablewalk enabled ? */
unsigned long linear_map_top;   /* Top of linear mapping */

#endif /* CONFIG_PPC64 */

/*
 * Base TLB flushing operations:
 *
 *  - flush_tlb_mm(mm) flushes the specified mm context TLB's
 *  - flush_tlb_page(vma, vmaddr) flushes one page
 *  - flush_tlb_range(vma, start, end) flushes a range of pages
 *  - flush_tlb_kernel_range(start, end) flushes kernel pages
 *
 *  - local_* variants of page and mm only apply to the current
 *    processor
 */

/*
 * These are the base non-SMP variants of page and mm flushing
 */
void local_flush_tlb_mm(struct mm_struct *mm)
{
        unsigned int pid;

        preempt_disable();
        pid = mm->context.id;
        if (pid != MMU_NO_CONTEXT)
                _tlbil_pid(pid);
        preempt_enable();
}
EXPORT_SYMBOL(local_flush_tlb_mm);

void __local_flush_tlb_page(struct mm_struct *mm, unsigned long vmaddr,
                            int tsize, int ind)
{
        unsigned int pid;

        preempt_disable();
        pid = mm ? mm->context.id : 0;
        if (pid != MMU_NO_CONTEXT)
                _tlbil_va(vmaddr, pid, tsize, ind);
        preempt_enable();
}

void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr)
{
        __local_flush_tlb_page(vma ? vma->vm_mm : NULL, vmaddr,
                               mmu_get_tsize(mmu_virtual_psize), 0);
}
EXPORT_SYMBOL(local_flush_tlb_page);

/*
 * And here are the SMP non-local implementations
 */
#ifdef CONFIG_SMP

static DEFINE_SPINLOCK(tlbivax_lock);

static int mm_is_core_local(struct mm_struct *mm)
{
        return cpumask_subset(mm_cpumask(mm),
                              topology_thread_cpumask(smp_processor_id()));
}

struct tlb_flush_param {
        unsigned long addr;
        unsigned int pid;
        unsigned int tsize;
        unsigned int ind;
};

static void do_flush_tlb_mm_ipi(void *param)
{
        struct tlb_flush_param *p = param;

        _tlbil_pid(p ? p->pid : 0);
}

static void do_flush_tlb_page_ipi(void *param)
{
        struct tlb_flush_param *p = param;

        _tlbil_va(p->addr, p->pid, p->tsize, p->ind);
}


/* Note on invalidations and PID:
 *
 * We snapshot the PID with preempt disabled. At this point, it can still
 * change either because:
 * - our context is being stolen (PID -> NO_CONTEXT) on another CPU
 * - we are invaliating some target that isn't currently running here
 *   and is concurrently acquiring a new PID on another CPU
 * - some other CPU is re-acquiring a lost PID for this mm
 * etc...
 *
 * However, this shouldn't be a problem as we only guarantee
 * invalidation of TLB entries present prior to this call, so we
 * don't care about the PID changing, and invalidating a stale PID
 * is generally harmless.
 */

void flush_tlb_mm(struct mm_struct *mm)
{
        unsigned int pid;

        preempt_disable();
        pid = mm->context.id;
        if (unlikely(pid == MMU_NO_CONTEXT))
                goto no_context;
        if (!mm_is_core_local(mm)) {
                struct tlb_flush_param p = { .pid = pid };
                /* Ignores smp_processor_id() even if set. */
                smp_call_function_many(mm_cpumask(mm),
                                       do_flush_tlb_mm_ipi, &p, 1);
        }
        _tlbil_pid(pid);
 no_context:
        preempt_enable();
}
EXPORT_SYMBOL(flush_tlb_mm);

void __flush_tlb_page(struct mm_struct *mm, unsigned long vmaddr,
                      int tsize, int ind)
{
        struct cpumask *cpu_mask;
        unsigned int pid;

        preempt_disable();
        pid = mm ? mm->context.id : 0;
        if (unlikely(pid == MMU_NO_CONTEXT))
                goto bail;
        cpu_mask = mm_cpumask(mm);
        if (!mm_is_core_local(mm)) {
                /* If broadcast tlbivax is supported, use it */
                if (mmu_has_feature(MMU_FTR_USE_TLBIVAX_BCAST)) {
                        int lock = mmu_has_feature(MMU_FTR_LOCK_BCAST_INVAL);
                        if (lock)
                                spin_lock(&tlbivax_lock);
                        _tlbivax_bcast(vmaddr, pid, tsize, ind);
                        if (lock)
                                spin_unlock(&tlbivax_lock);
                        goto bail;
                } else {
                        struct tlb_flush_param p = {
                                .pid = pid,
                                .addr = vmaddr,
                                .tsize = tsize,
                                .ind = ind,
                        };
                        /* Ignores smp_processor_id() even if set in cpu_mask */
                        smp_call_function_many(cpu_mask,
                                               do_flush_tlb_page_ipi, &p, 1);
                }
        }
        _tlbil_va(vmaddr, pid, tsize, ind);
 bail:
        preempt_enable();
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr)
{
        __flush_tlb_page(vma ? vma->vm_mm : NULL, vmaddr,
                         mmu_get_tsize(mmu_virtual_psize), 0);
}
EXPORT_SYMBOL(flush_tlb_page);

#endif /* CONFIG_SMP */

/*
 * Flush kernel TLB entries in the given range
 */
void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
#ifdef CONFIG_SMP
        preempt_disable();
        smp_call_function(do_flush_tlb_mm_ipi, NULL, 1);
        _tlbil_pid(0);
        preempt_enable();
#else
        _tlbil_pid(0);
#endif
}
EXPORT_SYMBOL(flush_tlb_kernel_range);

/*
 * Currently, for range flushing, we just do a full mm flush. This should
 * be optimized based on a threshold on the size of the range, since
 * some implementation can stack multiple tlbivax before a tlbsync but
 * for now, we keep it that way
 */
void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
                     unsigned long end)

{
        flush_tlb_mm(vma->vm_mm);
}
EXPORT_SYMBOL(flush_tlb_range);

void tlb_flush(struct mmu_gather *tlb)
{
        flush_tlb_mm(tlb->mm);

        /* Push out batch of freed page tables */
        pte_free_finish();
}

/*
 * Below are functions specific to the 64-bit variant of Book3E though that
 * may change in the future
 */

#ifdef CONFIG_PPC64

/*
 * Handling of virtual linear page tables or indirect TLB entries
 * flushing when PTE pages are freed
 */
void tlb_flush_pgtable(struct mmu_gather *tlb, unsigned long address)
{
        int tsize = mmu_psize_defs[mmu_pte_psize].enc;

        if (book3e_htw_enabled) {
                unsigned long start = address & PMD_MASK;
                unsigned long end = address + PMD_SIZE;
                unsigned long size = 1UL << mmu_psize_defs[mmu_pte_psize].shift;

                /* This isn't the most optimal, ideally we would factor out the
                 * while preempt & CPU mask mucking around, or even the IPI but
                 * it will do for now
                 */
                while (start < end) {
                        __flush_tlb_page(tlb->mm, start, tsize, 1);
                        start += size;
                }
        } else {
                unsigned long rmask = 0xf000000000000000ul;
                unsigned long rid = (address & rmask) | 0x1000000000000000ul;
                unsigned long vpte = address & ~rmask;

#ifdef CONFIG_PPC_64K_PAGES
                vpte = (vpte >> (PAGE_SHIFT - 4)) & ~0xfffful;
#else
                vpte = (vpte >> (PAGE_SHIFT - 3)) & ~0xffful;
#endif
                vpte |= rid;
                __flush_tlb_page(tlb->mm, vpte, tsize, 0);
        }
}

/*
 * Early initialization of the MMU TLB code
 */
static void __early_init_mmu(int boot_cpu)
{
        extern unsigned int interrupt_base_book3e;
        extern unsigned int exc_data_tlb_miss_htw_book3e;
        extern unsigned int exc_instruction_tlb_miss_htw_book3e;

        unsigned int *ibase = &interrupt_base_book3e;
        unsigned int mas4;

        /* XXX This will have to be decided at runtime, but right
         * now our boot and TLB miss code hard wires it. Ideally
         * we should find out a suitable page size and patch the
         * TLB miss code (either that or use the PACA to store
         * the value we want)
         */
        mmu_linear_psize = MMU_PAGE_1G;

        /* XXX This should be decided at runtime based on supported
         * page sizes in the TLB, but for now let's assume 16M is
         * always there and a good fit (which it probably is)
         */
        mmu_vmemmap_psize = MMU_PAGE_16M;

        /* Check if HW tablewalk is present, and if yes, enable it by:
         *
         * - patching the TLB miss handlers to branch to the
         *   one dedicates to it
         *
         * - setting the global book3e_htw_enabled
         *
         * - Set MAS4:INDD and default page size
         */

        /* XXX This code only checks for TLB 0 capabilities and doesn't
         *     check what page size combos are supported by the HW. It
         *     also doesn't handle the case where a separate array holds
         *     the IND entries from the array loaded by the PT.
         */
        if (boot_cpu) {
                unsigned int tlb0cfg = mfspr(SPRN_TLB0CFG);

                /* Check if HW loader is supported */
                if ((tlb0cfg & TLBnCFG_IND) &&
                    (tlb0cfg & TLBnCFG_PT)) {
                        patch_branch(ibase + (0x1c0 / 4),
                             (unsigned long)&exc_data_tlb_miss_htw_book3e, 0);
                        patch_branch(ibase + (0x1e0 / 4),
                             (unsigned long)&exc_instruction_tlb_miss_htw_book3e, 0);
                        book3e_htw_enabled = 1;
                }
                pr_info("MMU: Book3E Page Tables %s\n",
                        book3e_htw_enabled ? "Enabled" : "Disabled");
        }

        /* Set MAS4 based on page table setting */

        mas4 = 0x4 << MAS4_WIMGED_SHIFT;
        if (book3e_htw_enabled) {
                mas4 |= mas4 | MAS4_INDD;
#ifdef CONFIG_PPC_64K_PAGES
                mas4 |= BOOK3E_PAGESZ_256M << MAS4_TSIZED_SHIFT;
                mmu_pte_psize = MMU_PAGE_256M;
#else
                mas4 |= BOOK3E_PAGESZ_1M << MAS4_TSIZED_SHIFT;
                mmu_pte_psize = MMU_PAGE_1M;
#endif
        } else {
#ifdef CONFIG_PPC_64K_PAGES
                mas4 |= BOOK3E_PAGESZ_64K << MAS4_TSIZED_SHIFT;
#else
                mas4 |= BOOK3E_PAGESZ_4K << MAS4_TSIZED_SHIFT;
#endif
                mmu_pte_psize = mmu_virtual_psize;
        }
        mtspr(SPRN_MAS4, mas4);

        /* Set the global containing the top of the linear mapping
         * for use by the TLB miss code
         */
        linear_map_top = lmb_end_of_DRAM();

        /* A sync won't hurt us after mucking around with
         * the MMU configuration
         */
        mb();
}

void __init early_init_mmu(void)
{
        __early_init_mmu(1);
}

void __cpuinit early_init_mmu_secondary(void)
{
        __early_init_mmu(0);
}

#endif /* CONFIG_PPC64 */