// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/memblock.h>
#ifdef CONFIG_BLK_DEV_INITRD
#include <linux/initrd.h>
#endif
#include <linux/of_fdt.h>
#include <linux/swap.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <asm/page.h>
#include <asm/sections.h>
#include <asm/arcregs.h>

pgd_t swapper_pg_dir[PTRS_PER_PGD] __aligned(PAGE_SIZE);
char empty_zero_page[PAGE_SIZE] __aligned(PAGE_SIZE);
EXPORT_SYMBOL(empty_zero_page);

static const unsigned long low_mem_start = CONFIG_LINUX_RAM_BASE;
static unsigned long low_mem_sz;

#ifdef CONFIG_HIGHMEM
static unsigned long min_high_pfn, max_high_pfn;
static phys_addr_t high_mem_start;
static phys_addr_t high_mem_sz;
unsigned long arch_pfn_offset;
EXPORT_SYMBOL(arch_pfn_offset);
#endif

long __init arc_get_mem_sz(void)
{
        return low_mem_sz;
}

/* User can over-ride above with "mem=nnn[KkMm]" in cmdline */
static int __init setup_mem_sz(char *str)
{
        low_mem_sz = memparse(str, NULL) & PAGE_MASK;

        /* early console might not be setup yet - it will show up later */
        pr_info("\"mem=%s\": mem sz set to %ldM\n", str, TO_MB(low_mem_sz));

        return 0;
}
early_param("mem", setup_mem_sz);

void __init early_init_dt_add_memory_arch(u64 base, u64 size)
{
        int in_use = 0;

        if (!low_mem_sz) {
                if (base != low_mem_start)
                        panic("CONFIG_LINUX_RAM_BASE != DT memory { }");

                low_mem_sz = size;
                in_use = 1;
                memblock_add_node(base, size, 0);
        } else {
#ifdef CONFIG_HIGHMEM
                high_mem_start = base;
                high_mem_sz = size;
                in_use = 1;
                memblock_add_node(base, size, 1);
                memblock_reserve(base, size);
#endif
        }

        pr_info("Memory @ %llx [%lldM] %s\n",
                base, TO_MB(size), !in_use ? "Not used":"");
}

bool arch_has_descending_max_zone_pfns(void)
{
        return !IS_ENABLED(CONFIG_ARC_HAS_PAE40);
}

/*
 * First memory setup routine called from setup_arch()
 * 1. setup swapper's mm @init_mm
 * 2. Count the pages we have and setup bootmem allocator
 * 3. zone setup
 */
void __init setup_arch_memory(void)
{
        unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };

        setup_initial_init_mm(_text, _etext, _edata, _end);

        /* first page of system - kernel .vector starts here */
        min_low_pfn = virt_to_pfn(CONFIG_LINUX_RAM_BASE);

        /* Last usable page of low mem */
        max_low_pfn = max_pfn = PFN_DOWN(low_mem_start + low_mem_sz);

        /*------------- bootmem allocator setup -----------------------*/

        /*
         * seed the bootmem allocator after any DT memory node parsing or
         * "mem=xxx" cmdline overrides have potentially updated @arc_mem_sz
         *
         * Only low mem is added, otherwise we have crashes when allocating
         * mem_map[] itself. NO_BOOTMEM allocates mem_map[] at the end of
         * avail memory, ending in highmem with a > 32-bit address. However
         * it then tries to memset it with a truncaed 32-bit handle, causing
         * the crash
         */

        memblock_reserve(CONFIG_LINUX_LINK_BASE,
                         __pa(_end) - CONFIG_LINUX_LINK_BASE);

#ifdef CONFIG_BLK_DEV_INITRD
        if (phys_initrd_size) {
                memblock_reserve(phys_initrd_start, phys_initrd_size);
                initrd_start = (unsigned long)__va(phys_initrd_start);
                initrd_end = initrd_start + phys_initrd_size;
        }
#endif

        early_init_fdt_reserve_self();
        early_init_fdt_scan_reserved_mem();

        memblock_dump_all();

        /*----------------- node/zones setup --------------------------*/
        max_zone_pfn[ZONE_NORMAL] = max_low_pfn;

#ifdef CONFIG_HIGHMEM
        /*
         * On ARC (w/o PAE) HIGHMEM addresses are actually smaller (0 based)
         * than addresses in normal aka low memory (0x8000_0000 based).
         * Even with PAE, the huge peripheral space hole would waste a lot of
         * mem with single contiguous mem_map[].
         * Thus when HIGHMEM on ARC is enabled the memory map corresponding
         * to the hole is freed and ARC specific version of pfn_valid()
         * handles the hole in the memory map.
         */

        min_high_pfn = PFN_DOWN(high_mem_start);
        max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz);

        /*
         * max_high_pfn should be ok here for both HIGHMEM and HIGHMEM+PAE.
         * For HIGHMEM without PAE max_high_pfn should be less than
         * min_low_pfn to guarantee that these two regions don't overlap.
         * For PAE case highmem is greater than lowmem, so it is natural
         * to use max_high_pfn.
         *
         * In both cases, holes should be handled by pfn_valid().
         */
        max_zone_pfn[ZONE_HIGHMEM] = max_high_pfn;

        high_memory = (void *)(min_high_pfn << PAGE_SHIFT);

        arch_pfn_offset = min(min_low_pfn, min_high_pfn);
        kmap_init();

#else /* CONFIG_HIGHMEM */
        /* pfn_valid() uses this when FLATMEM=y and HIGHMEM=n */
        max_mapnr = max_low_pfn - min_low_pfn;

#endif /* CONFIG_HIGHMEM */

        free_area_init(max_zone_pfn);
}

static void __init highmem_init(void)
{
#ifdef CONFIG_HIGHMEM
        unsigned long tmp;

        memblock_free(high_mem_start, high_mem_sz);
        for (tmp = min_high_pfn; tmp < max_high_pfn; tmp++)
                free_highmem_page(pfn_to_page(tmp));
#endif
}

/*
 * mem_init - initializes memory
 *
 * Frees up bootmem
 * Calculates and displays memory available/used
 */
void __init mem_init(void)
{
        memblock_free_all();
        highmem_init();

        BUILD_BUG_ON((PTRS_PER_PGD * sizeof(pgd_t)) > PAGE_SIZE);
        BUILD_BUG_ON((PTRS_PER_PUD * sizeof(pud_t)) > PAGE_SIZE);
        BUILD_BUG_ON((PTRS_PER_PMD * sizeof(pmd_t)) > PAGE_SIZE);
        BUILD_BUG_ON((PTRS_PER_PTE * sizeof(pte_t)) > PAGE_SIZE);
}

#ifdef CONFIG_HIGHMEM
int pfn_valid(unsigned long pfn)
{
        return (pfn >= min_high_pfn && pfn <= max_high_pfn) ||
                (pfn >= min_low_pfn && pfn <= max_low_pfn);
}
EXPORT_SYMBOL(pfn_valid);
#endif