/*
 * PPC Huge TLB Page Support for Kernel.
 *
 * Copyright (C) 2003 David Gibson, IBM Corporation.
 * Copyright (C) 2011 Becky Bruce, Freescale Semiconductor
 *
 * Based on the IA-32 version:
 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
 */

#include <linux/mm.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>
#include <linux/export.h>
#include <linux/of_fdt.h>
#include <linux/memblock.h>
#include <linux/moduleparam.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/kmemleak.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/setup.h>
#include <asm/hugetlb.h>
#include <asm/pte-walk.h>
#include <asm/firmware.h>

bool hugetlb_disabled = false;

#define PTE_T_ORDER     (__builtin_ffs(sizeof(pte_basic_t)) - \
                         __builtin_ffs(sizeof(void *)))

pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz)
{
        /*
         * Only called for hugetlbfs pages, hence can ignore THP and the
         * irq disabled walk.
         */
        return __find_linux_pte(mm->pgd, addr, NULL, NULL);
}

pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
                      unsigned long addr, unsigned long sz)
{
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;

        addr &= ~(sz - 1);

        p4d = p4d_offset(pgd_offset(mm, addr), addr);
        if (!mm_pud_folded(mm) && sz >= P4D_SIZE)
                return (pte_t *)p4d;

        pud = pud_alloc(mm, p4d, addr);
        if (!pud)
                return NULL;
        if (!mm_pmd_folded(mm) && sz >= PUD_SIZE)
                return (pte_t *)pud;

        pmd = pmd_alloc(mm, pud, addr);
        if (!pmd)
                return NULL;

        if (sz >= PMD_SIZE) {
                /* On 8xx, all hugepages are handled as contiguous PTEs */
                if (IS_ENABLED(CONFIG_PPC_8xx)) {
                        int i;

                        for (i = 0; i < sz / PMD_SIZE; i++) {
                                if (!pte_alloc_huge(mm, pmd + i, addr))
                                        return NULL;
                        }
                }
                return (pte_t *)pmd;
        }

        return pte_alloc_huge(mm, pmd, addr);
}

#ifdef CONFIG_PPC_BOOK3S_64
/*
 * Tracks gpages after the device tree is scanned and before the
 * huge_boot_pages list is ready on pseries.
 */
#define MAX_NUMBER_GPAGES       1024
__initdata static u64 gpage_freearray[MAX_NUMBER_GPAGES];
__initdata static unsigned nr_gpages;

/*
 * Build list of addresses of gigantic pages.  This function is used in early
 * boot before the buddy allocator is setup.
 */
void __init pseries_add_gpage(u64 addr, u64 page_size, unsigned long number_of_pages)
{
        if (!addr)
                return;
        while (number_of_pages > 0) {
                gpage_freearray[nr_gpages] = addr;
                nr_gpages++;
                number_of_pages--;
                addr += page_size;
        }
}

static int __init pseries_alloc_bootmem_huge_page(struct hstate *hstate)
{
        struct huge_bootmem_page *m;
        if (nr_gpages == 0)
                return 0;
        m = phys_to_virt(gpage_freearray[--nr_gpages]);
        gpage_freearray[nr_gpages] = 0;
        list_add(&m->list, &huge_boot_pages[0]);
        m->hstate = hstate;
        m->flags = 0;
        return 1;
}

bool __init hugetlb_node_alloc_supported(void)
{
        return false;
}
#endif


int __init alloc_bootmem_huge_page(struct hstate *h, int nid)
{

#ifdef CONFIG_PPC_BOOK3S_64
        if (firmware_has_feature(FW_FEATURE_LPAR) && !radix_enabled())
                return pseries_alloc_bootmem_huge_page(h);
#endif
        return __alloc_bootmem_huge_page(h, nid);
}

bool __init arch_hugetlb_valid_size(unsigned long size)
{
        int shift = __ffs(size);
        int mmu_psize;

        /* Check that it is a page size supported by the hardware and
         * that it fits within pagetable and slice limits. */
        if (size <= PAGE_SIZE || !is_power_of_2(size))
                return false;

        mmu_psize = check_and_get_huge_psize(shift);
        if (mmu_psize < 0)
                return false;

        BUG_ON(mmu_psize_defs[mmu_psize].shift != shift);

        return true;
}

static int __init add_huge_page_size(unsigned long long size)
{
        int shift = __ffs(size);

        if (!arch_hugetlb_valid_size((unsigned long)size))
                return -EINVAL;

        hugetlb_add_hstate(shift - PAGE_SHIFT);
        return 0;
}

static int __init hugetlbpage_init(void)
{
        bool configured = false;
        int psize;

        if (hugetlb_disabled) {
                pr_info("HugeTLB support is disabled!\n");
                return 0;
        }

        if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && !radix_enabled() &&
            !mmu_has_feature(MMU_FTR_16M_PAGE))
                return -ENODEV;

        for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
                unsigned shift;

                if (!mmu_psize_defs[psize].shift)
                        continue;

                shift = mmu_psize_to_shift(psize);

                if (add_huge_page_size(1ULL << shift) < 0)
                        continue;

                configured = true;
        }

        if (!configured)
                pr_info("Failed to initialize. Disabling HugeTLB");

        return 0;
}

arch_initcall(hugetlbpage_init);

unsigned int __init arch_hugetlb_cma_order(void)
{
        if (radix_enabled())
                return PUD_SHIFT - PAGE_SHIFT;
        else if (!firmware_has_feature(FW_FEATURE_LPAR) && mmu_psize_defs[MMU_PAGE_16G].shift)
                /*
                 * For pseries we do use ibm,expected#pages for reserving 16G pages.
                 */
                return mmu_psize_to_shift(MMU_PAGE_16G) - PAGE_SHIFT;

        return 0;
}