// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * OpenRISC idle.c
 *
 * Linux architectural port borrowing liberally from similar works of
 * others.  All original copyrights apply as per the original source
 * declaration.
 *
 * Modifications for the OpenRISC architecture:
 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
 */

#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/memblock.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/blkdev.h>       /* for initrd_* */
#include <linux/pagemap.h>

#include <asm/pgalloc.h>
#include <asm/dma.h>
#include <asm/io.h>
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#include <asm/fixmap.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>

int mem_init_done;

DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);

static void __init zone_sizes_init(void)
{
        unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };

        /*
         * We use only ZONE_NORMAL
         */
        max_zone_pfn[ZONE_NORMAL] = max_low_pfn;

        free_area_init(max_zone_pfn);
}

extern const char _s_kernel_ro[], _e_kernel_ro[];

/*
 * Map all physical memory into kernel's address space.
 *
 * This is explicitly coded for two-level page tables, so if you need
 * something else then this needs to change.
 */
static void __init map_ram(void)
{
        phys_addr_t start, end;
        unsigned long v, p, e;
        pgprot_t prot;
        pgd_t *pge;
        p4d_t *p4e;
        pud_t *pue;
        pmd_t *pme;
        pte_t *pte;
        u64 i;
        /* These mark extents of read-only kernel pages...
         * ...from vmlinux.lds.S
         */
        struct memblock_region *region;

        v = PAGE_OFFSET;

        for_each_mem_range(i, &start, &end) {
                p = (u32) start & PAGE_MASK;
                e = (u32) end;

                v = (u32) __va(p);
                pge = pgd_offset_k(v);

                while (p < e) {
                        int j;
                        p4e = p4d_offset(pge, v);
                        pue = pud_offset(p4e, v);
                        pme = pmd_offset(pue, v);

                        if ((u32) pue != (u32) pge || (u32) pme != (u32) pge) {
                                panic("%s: OR1K kernel hardcoded for "
                                      "two-level page tables",
                                     __func__);
                        }

                        /* Alloc one page for holding PTE's... */
                        pte = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
                        if (!pte)
                                panic("%s: Failed to allocate page for PTEs\n",
                                      __func__);
                        set_pmd(pme, __pmd(_KERNPG_TABLE + __pa(pte)));

                        /* Fill the newly allocated page with PTE'S */
                        for (j = 0; p < e && j < PTRS_PER_PTE;
                             v += PAGE_SIZE, p += PAGE_SIZE, j++, pte++) {
                                if (v >= (u32) _e_kernel_ro ||
                                    v < (u32) _s_kernel_ro)
                                        prot = PAGE_KERNEL;
                                else
                                        prot = PAGE_KERNEL_RO;

                                set_pte(pte, mk_pte_phys(p, prot));
                        }

                        pge++;
                }

                printk(KERN_INFO "%s: Memory: 0x%x-0x%x\n", __func__,
                       region->base, region->base + region->size);
        }
}

void __init paging_init(void)
{
        extern void tlb_init(void);

        unsigned long end;
        int i;

        printk(KERN_INFO "Setting up paging and PTEs.\n");

        /* clear out the init_mm.pgd that will contain the kernel's mappings */

        for (i = 0; i < PTRS_PER_PGD; i++)
                swapper_pg_dir[i] = __pgd(0);

        /* make sure the current pgd table points to something sane
         * (even if it is most probably not used until the next
         *  switch_mm)
         */
        current_pgd[smp_processor_id()] = init_mm.pgd;

        end = (unsigned long)__va(max_low_pfn * PAGE_SIZE);

        map_ram();

        zone_sizes_init();

        /* self modifying code ;) */
        /* Since the old TLB miss handler has been running up until now,
         * the kernel pages are still all RW, so we can still modify the
         * text directly... after this change and a TLB flush, the kernel
         * pages will become RO.
         */
        {
                extern unsigned long dtlb_miss_handler;
                extern unsigned long itlb_miss_handler;

                unsigned long *dtlb_vector = __va(0x900);
                unsigned long *itlb_vector = __va(0xa00);

                printk(KERN_INFO "itlb_miss_handler %p\n", &itlb_miss_handler);
                *itlb_vector = ((unsigned long)&itlb_miss_handler -
                                (unsigned long)itlb_vector) >> 2;

                /* Soft ordering constraint to ensure that dtlb_vector is
                 * the last thing updated
                 */
                barrier();

                printk(KERN_INFO "dtlb_miss_handler %p\n", &dtlb_miss_handler);
                *dtlb_vector = ((unsigned long)&dtlb_miss_handler -
                                (unsigned long)dtlb_vector) >> 2;

        }

        /* Soft ordering constraint to ensure that cache invalidation and
         * TLB flush really happen _after_ code has been modified.
         */
        barrier();

        /* Invalidate instruction caches after code modification */
        mtspr(SPR_ICBIR, 0x900);
        mtspr(SPR_ICBIR, 0xa00);

        /* New TLB miss handlers and kernel page tables are in now place.
         * Make sure that page flags get updated for all pages in TLB by
         * flushing the TLB and forcing all TLB entries to be recreated
         * from their page table flags.
         */
        flush_tlb_all();
}

/* References to section boundaries */

void __init mem_init(void)
{
        BUG_ON(!mem_map);

        max_mapnr = max_low_pfn;
        high_memory = (void *)__va(max_low_pfn * PAGE_SIZE);

        /* clear the zero-page */
        memset((void *)empty_zero_page, 0, PAGE_SIZE);

        /* this will put all low memory onto the freelists */
        memblock_free_all();

        mem_init_print_info(NULL);

        printk("mem_init_done ...........................................\n");
        mem_init_done = 1;
        return;
}