/*
 * Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 */

#include <common.h>
#include <physmem.h>
#include <asm/cpu.h>
#include <linux/compiler.h>

DECLARE_GLOBAL_DATA_PTR;

/* Large pages are 2MB. */
#define LARGE_PAGE_SIZE ((1 << 20) * 2)

/*
 * Paging data structures.
 */

struct pdpe {
        uint64_t p:1;
        uint64_t mbz_0:2;
        uint64_t pwt:1;
        uint64_t pcd:1;
        uint64_t mbz_1:4;
        uint64_t avl:3;
        uint64_t base:40;
        uint64_t mbz_2:12;
};

typedef struct pdpe pdpt_t[512];

struct pde {
        uint64_t p:1;      /* present */
        uint64_t rw:1;     /* read/write */
        uint64_t us:1;     /* user/supervisor */
        uint64_t pwt:1;    /* page-level writethrough */
        uint64_t pcd:1;    /* page-level cache disable */
        uint64_t a:1;      /* accessed */
        uint64_t d:1;      /* dirty */
        uint64_t ps:1;     /* page size */
        uint64_t g:1;      /* global page */
        uint64_t avl:3;    /* available to software */
        uint64_t pat:1;    /* page-attribute table */
        uint64_t mbz_0:8;  /* must be zero */
        uint64_t base:31;  /* base address */
};

typedef struct pde pdt_t[512];

static pdpt_t pdpt __aligned(4096);
static pdt_t pdts[4] __aligned(4096);

/*
 * Map a virtual address to a physical address and optionally invalidate any
 * old mapping.
 *
 * @param virt          The virtual address to use.
 * @param phys          The physical address to use.
 * @param invlpg        Whether to use invlpg to clear any old mappings.
 */
static void x86_phys_map_page(uintptr_t virt, phys_addr_t phys, int invlpg)
{
        /* Extract the two bit PDPT index and the 9 bit PDT index. */
        uintptr_t pdpt_idx = (virt >> 30) & 0x3;
        uintptr_t pdt_idx = (virt >> 21) & 0x1ff;

        /* Set up a handy pointer to the appropriate PDE. */
        struct pde *pde = &(pdts[pdpt_idx][pdt_idx]);

        memset(pde, 0, sizeof(struct pde));
        pde->p = 1;
        pde->rw = 1;
        pde->us = 1;
        pde->ps = 1;
        pde->base = phys >> 21;

        if (invlpg) {
                /* Flush any stale mapping out of the TLBs. */
                __asm__ __volatile__(
                        "invlpg %0\n\t"
                        :
                        : "m" (*(uint8_t *)virt)
                );
        }
}

/* Identity map the lower 4GB and turn on paging with PAE. */
static void x86_phys_enter_paging(void)
{
        phys_addr_t page_addr;
        unsigned i;

        /* Zero out the page tables. */
        memset(pdpt, 0, sizeof(pdpt));
        memset(pdts, 0, sizeof(pdts));

        /* Set up the PDPT. */
        for (i = 0; i < ARRAY_SIZE(pdts); i++) {
                pdpt[i].p = 1;
                pdpt[i].base = ((uintptr_t)&pdts[i]) >> 12;
        }

        /* Identity map everything up to 4GB. */
        for (page_addr = 0; page_addr < (1ULL << 32);
                        page_addr += LARGE_PAGE_SIZE) {
                /* There's no reason to invalidate the TLB with paging off. */
                x86_phys_map_page(page_addr, page_addr, 0);
        }

        cpu_enable_paging_pae((ulong)pdpt);
}

/* Disable paging and PAE mode. */
static void x86_phys_exit_paging(void)
{
        cpu_disable_paging_pae();
}

/*
 * Set physical memory to a particular value when the whole region fits on one
 * page.
 *
 * @param map_addr      The address that starts the physical page.
 * @param offset        How far into that page to start setting a value.
 * @param c             The value to set memory to.
 * @param size          The size in bytes of the area to set.
 */
static void x86_phys_memset_page(phys_addr_t map_addr, uintptr_t offset, int c,
                                 unsigned size)
{
        /*
         * U-Boot should be far away from the beginning of memory, so that's a
         * good place to map our window on top of.
         */
        const uintptr_t window = LARGE_PAGE_SIZE;

        /* Make sure the window is below U-Boot. */
        assert(window + LARGE_PAGE_SIZE <
               gd->relocaddr - CONFIG_SYS_MALLOC_LEN - CONFIG_SYS_STACK_SIZE);
        /* Map the page into the window and then memset the appropriate part. */
        x86_phys_map_page(window, map_addr, 1);
        memset((void *)(window + offset), c, size);
}

/*
 * A physical memory anologue to memset with matching parameters and return
 * value.
 */
phys_addr_t arch_phys_memset(phys_addr_t start, int c, phys_size_t size)
{
        const phys_addr_t max_addr = (phys_addr_t)~(uintptr_t)0;
        const phys_addr_t orig_start = start;

        if (!size)
                return orig_start;

        /* Handle memory below 4GB. */
        if (start <= max_addr) {
                phys_size_t low_size = min(max_addr + 1 - start, size);
                void *start_ptr = (void *)(uintptr_t)start;

                assert(((phys_addr_t)(uintptr_t)start) == start);
                memset(start_ptr, c, low_size);
                start += low_size;
                size -= low_size;
        }

        /* Use paging and PAE to handle memory above 4GB up to 64GB. */
        if (size) {
                phys_addr_t map_addr = start & ~(LARGE_PAGE_SIZE - 1);
                phys_addr_t offset = start - map_addr;

                x86_phys_enter_paging();

                /* Handle the first partial page. */
                if (offset) {
                        phys_addr_t end =
                                min(map_addr + LARGE_PAGE_SIZE, start + size);
                        phys_size_t cur_size = end - start;
                        x86_phys_memset_page(map_addr, offset, c, cur_size);
                        size -= cur_size;
                        map_addr += LARGE_PAGE_SIZE;
                }
                /* Handle the complete pages. */
                while (size > LARGE_PAGE_SIZE) {
                        x86_phys_memset_page(map_addr, 0, c, LARGE_PAGE_SIZE);
                        size -= LARGE_PAGE_SIZE;
                        map_addr += LARGE_PAGE_SIZE;
                }
                /* Handle the last partial page. */
                if (size)
                        x86_phys_memset_page(map_addr, 0, c, size);

                x86_phys_exit_paging();
        }
        return orig_start;
}