/*
 * SPU local store allocation routines
 *
 * Copyright 2007 Benjamin Herrenschmidt, IBM Corp.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include <asm/spu.h>
#include <asm/spu_csa.h>
#include <asm/mmu.h>

#include "spufs.h"

static int spu_alloc_lscsa_std(struct spu_state *csa)
{
        struct spu_lscsa *lscsa;
        unsigned char *p;

        lscsa = vzalloc(sizeof(struct spu_lscsa));
        if (!lscsa)
                return -ENOMEM;
        csa->lscsa = lscsa;

        /* Set LS pages reserved to allow for user-space mapping. */
        for (p = lscsa->ls; p < lscsa->ls + LS_SIZE; p += PAGE_SIZE)
                SetPageReserved(vmalloc_to_page(p));

        return 0;
}

static void spu_free_lscsa_std(struct spu_state *csa)
{
        /* Clear reserved bit before vfree. */
        unsigned char *p;

        if (csa->lscsa == NULL)
                return;

        for (p = csa->lscsa->ls; p < csa->lscsa->ls + LS_SIZE; p += PAGE_SIZE)
                ClearPageReserved(vmalloc_to_page(p));

        vfree(csa->lscsa);
}

#ifdef CONFIG_SPU_FS_64K_LS

#define SPU_64K_PAGE_SHIFT      16
#define SPU_64K_PAGE_ORDER      (SPU_64K_PAGE_SHIFT - PAGE_SHIFT)
#define SPU_64K_PAGE_COUNT      (1ul << SPU_64K_PAGE_ORDER)

int spu_alloc_lscsa(struct spu_state *csa)
{
        struct page     **pgarray;
        unsigned char   *p;
        int             i, j, n_4k;

        /* Check availability of 64K pages */
        if (!spu_64k_pages_available())
                goto fail;

        csa->use_big_pages = 1;

        pr_debug("spu_alloc_lscsa(csa=0x%p), trying to allocate 64K pages\n",
                 csa);

        /* First try to allocate our 64K pages. We need 5 of them
         * with the current implementation. In the future, we should try
         * to separate the lscsa with the actual local store image, thus
         * allowing us to require only 4 64K pages per context
         */
        for (i = 0; i < SPU_LSCSA_NUM_BIG_PAGES; i++) {
                /* XXX This is likely to fail, we should use a special pool
                 *     similar to what hugetlbfs does.
                 */
                csa->lscsa_pages[i] = alloc_pages(GFP_KERNEL,
                                                  SPU_64K_PAGE_ORDER);
                if (csa->lscsa_pages[i] == NULL)
                        goto fail;
        }

        pr_debug(" success ! creating vmap...\n");

        /* Now we need to create a vmalloc mapping of these for the kernel
         * and SPU context switch code to use. Currently, we stick to a
         * normal kernel vmalloc mapping, which in our case will be 4K
         */
        n_4k = SPU_64K_PAGE_COUNT * SPU_LSCSA_NUM_BIG_PAGES;
        pgarray = kmalloc(sizeof(struct page *) * n_4k, GFP_KERNEL);
        if (pgarray == NULL)
                goto fail;
        for (i = 0; i < SPU_LSCSA_NUM_BIG_PAGES; i++)
                for (j = 0; j < SPU_64K_PAGE_COUNT; j++)
                        /* We assume all the struct page's are contiguous
                         * which should be hopefully the case for an order 4
                         * allocation..
                         */
                        pgarray[i * SPU_64K_PAGE_COUNT + j] =
                                csa->lscsa_pages[i] + j;
        csa->lscsa = vmap(pgarray, n_4k, VM_USERMAP, PAGE_KERNEL);
        kfree(pgarray);
        if (csa->lscsa == NULL)
                goto fail;

        memset(csa->lscsa, 0, sizeof(struct spu_lscsa));

        /* Set LS pages reserved to allow for user-space mapping.
         *
         * XXX isn't that a bit obsolete ? I think we should just
         * make sure the page count is high enough. Anyway, won't harm
         * for now
         */
        for (p = csa->lscsa->ls; p < csa->lscsa->ls + LS_SIZE; p += PAGE_SIZE)
                SetPageReserved(vmalloc_to_page(p));

        pr_debug(" all good !\n");

        return 0;
fail:
        pr_debug("spufs: failed to allocate lscsa 64K pages, falling back\n");
        spu_free_lscsa(csa);
        return spu_alloc_lscsa_std(csa);
}

void spu_free_lscsa(struct spu_state *csa)
{
        unsigned char *p;
        int i;

        if (!csa->use_big_pages) {
                spu_free_lscsa_std(csa);
                return;
        }
        csa->use_big_pages = 0;

        if (csa->lscsa == NULL)
                goto free_pages;

        for (p = csa->lscsa->ls; p < csa->lscsa->ls + LS_SIZE; p += PAGE_SIZE)
                ClearPageReserved(vmalloc_to_page(p));

        vunmap(csa->lscsa);
        csa->lscsa = NULL;

 free_pages:

        for (i = 0; i < SPU_LSCSA_NUM_BIG_PAGES; i++)
                if (csa->lscsa_pages[i])
                        __free_pages(csa->lscsa_pages[i], SPU_64K_PAGE_ORDER);
}

#else /* CONFIG_SPU_FS_64K_LS */

int spu_alloc_lscsa(struct spu_state *csa)
{
        return spu_alloc_lscsa_std(csa);
}

void spu_free_lscsa(struct spu_state *csa)
{
        spu_free_lscsa_std(csa);
}

#endif /* !defined(CONFIG_SPU_FS_64K_LS) */