// SPDX-License-Identifier: GPL-2.0
/*
 * Re-map IO memory to kernel address space so that we can access it.
 *
 * These functions should only be used when it is necessary to map a
 * physical address space into the kernel address space before ioremap()
 * can be used, e.g. early in boot before paging_init().
 *
 * Copyright (C) 2009  Matt Fleming
 */

#include <linux/vmalloc.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/proc_fs.h>
#include <asm/fixmap.h>
#include <asm/page.h>
#include <asm/addrspace.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include "ioremap.h"

struct ioremap_map {
        void __iomem *addr;
        unsigned long size;
        unsigned long fixmap_addr;
};

static struct ioremap_map ioremap_maps[FIX_N_IOREMAPS];

void __init ioremap_fixed_init(void)
{
        struct ioremap_map *map;
        int i;

        for (i = 0; i < FIX_N_IOREMAPS; i++) {
                map = &ioremap_maps[i];
                map->fixmap_addr = __fix_to_virt(FIX_IOREMAP_BEGIN + i);
        }
}

void __init __iomem *
ioremap_fixed(phys_addr_t phys_addr, unsigned long size, pgprot_t prot)
{
        enum fixed_addresses idx0, idx;
        struct ioremap_map *map;
        unsigned int nrpages;
        unsigned long offset;
        int i, slot;

        /*
         * Mappings have to be page-aligned
         */
        offset = phys_addr & ~PAGE_MASK;
        phys_addr &= PAGE_MASK;
        size = PAGE_ALIGN(phys_addr + size) - phys_addr;

        slot = -1;
        for (i = 0; i < FIX_N_IOREMAPS; i++) {
                map = &ioremap_maps[i];
                if (!map->addr) {
                        map->size = size;
                        slot = i;
                        break;
                }
        }

        if (slot < 0)
                return NULL;

        /*
         * Mappings have to fit in the FIX_IOREMAP area.
         */
        nrpages = size >> PAGE_SHIFT;
        if (nrpages > FIX_N_IOREMAPS)
                return NULL;

        /*
         * Ok, go for it..
         */
        idx0 = FIX_IOREMAP_BEGIN + slot;
        idx = idx0;
        while (nrpages > 0) {
                pgprot_val(prot) |= _PAGE_WIRED;
                __set_fixmap(idx, phys_addr, prot);
                phys_addr += PAGE_SIZE;
                idx++;
                --nrpages;
        }

        map->addr = (void __iomem *)(offset + map->fixmap_addr);
        return map->addr;
}

int iounmap_fixed(void __iomem *addr)
{
        enum fixed_addresses idx;
        struct ioremap_map *map;
        unsigned int nrpages;
        int i, slot;

        slot = -1;
        for (i = 0; i < FIX_N_IOREMAPS; i++) {
                map = &ioremap_maps[i];
                if (map->addr == addr) {
                        slot = i;
                        break;
                }
        }

        /*
         * If we don't match, it's not for us.
         */
        if (slot < 0)
                return -EINVAL;

        nrpages = map->size >> PAGE_SHIFT;

        idx = FIX_IOREMAP_BEGIN + slot + nrpages - 1;
        while (nrpages > 0) {
                __clear_fixmap(idx, __pgprot(_PAGE_WIRED));
                --idx;
                --nrpages;
        }

        map->size = 0;
        map->addr = NULL;

        return 0;
}