// SPDX-License-Identifier: GPL-2.0-only
/*
 * OMAP Crypto driver common support routines.
 *
 * Copyright (c) 2017 Texas Instruments Incorporated
 *   Tero Kristo <t-kristo@ti.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/scatterlist.h>
#include <crypto/scatterwalk.h>

#include "omap-crypto.h"

static int omap_crypto_copy_sg_lists(int total, int bs,
                                     struct scatterlist **sg,
                                     struct scatterlist *new_sg, u16 flags)
{
        int n = sg_nents(*sg);
        struct scatterlist *tmp;

        if (!(flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY)) {
                new_sg = kmalloc_objs(*new_sg, n);
                if (!new_sg)
                        return -ENOMEM;

                sg_init_table(new_sg, n);
        }

        tmp = new_sg;

        while (*sg && total) {
                int len = (*sg)->length;

                if (total < len)
                        len = total;

                if (len > 0) {
                        total -= len;
                        sg_set_page(tmp, sg_page(*sg), len, (*sg)->offset);
                        if (total <= 0)
                                sg_mark_end(tmp);
                        tmp = sg_next(tmp);
                }

                *sg = sg_next(*sg);
        }

        *sg = new_sg;

        return 0;
}

static int omap_crypto_copy_sgs(int total, int bs, struct scatterlist **sg,
                                struct scatterlist *new_sg, u16 flags)
{
        void *buf;
        int pages;
        int new_len;

        new_len = ALIGN(total, bs);
        pages = get_order(new_len);

        buf = (void *)__get_free_pages(GFP_ATOMIC, pages);
        if (!buf) {
                pr_err("%s: Couldn't allocate pages for unaligned cases.\n",
                       __func__);
                return -ENOMEM;
        }

        if (flags & OMAP_CRYPTO_COPY_DATA) {
                scatterwalk_map_and_copy(buf, *sg, 0, total, 0);
                if (flags & OMAP_CRYPTO_ZERO_BUF)
                        memset(buf + total, 0, new_len - total);
        }

        if (!(flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY))
                sg_init_table(new_sg, 1);

        sg_set_buf(new_sg, buf, new_len);

        *sg = new_sg;

        return 0;
}

static int omap_crypto_check_sg(struct scatterlist *sg, int total, int bs,
                                u16 flags)
{
        int len = 0;
        int num_sg = 0;

        if (!IS_ALIGNED(total, bs))
                return OMAP_CRYPTO_NOT_ALIGNED;

        while (sg) {
                num_sg++;

                if (!IS_ALIGNED(sg->offset, 4))
                        return OMAP_CRYPTO_NOT_ALIGNED;
                if (!IS_ALIGNED(sg->length, bs))
                        return OMAP_CRYPTO_NOT_ALIGNED;
#ifdef CONFIG_ZONE_DMA
                if (page_zonenum(sg_page(sg)) != ZONE_DMA)
                        return OMAP_CRYPTO_NOT_ALIGNED;
#endif

                len += sg->length;
                sg = sg_next(sg);

                if (len >= total)
                        break;
        }

        if ((flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY) && num_sg > 1)
                return OMAP_CRYPTO_NOT_ALIGNED;

        if (len != total)
                return OMAP_CRYPTO_BAD_DATA_LENGTH;

        return 0;
}

int omap_crypto_align_sg(struct scatterlist **sg, int total, int bs,
                         struct scatterlist *new_sg, u16 flags,
                         u8 flags_shift, unsigned long *dd_flags)
{
        int ret;

        *dd_flags &= ~(OMAP_CRYPTO_COPY_MASK << flags_shift);

        if (flags & OMAP_CRYPTO_FORCE_COPY)
                ret = OMAP_CRYPTO_NOT_ALIGNED;
        else
                ret = omap_crypto_check_sg(*sg, total, bs, flags);

        if (ret == OMAP_CRYPTO_NOT_ALIGNED) {
                ret = omap_crypto_copy_sgs(total, bs, sg, new_sg, flags);
                if (ret)
                        return ret;
                *dd_flags |= OMAP_CRYPTO_DATA_COPIED << flags_shift;
        } else if (ret == OMAP_CRYPTO_BAD_DATA_LENGTH) {
                ret = omap_crypto_copy_sg_lists(total, bs, sg, new_sg, flags);
                if (ret)
                        return ret;
                if (!(flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY))
                        *dd_flags |= OMAP_CRYPTO_SG_COPIED << flags_shift;
        } else if (flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY) {
                sg_set_buf(new_sg, sg_virt(*sg), (*sg)->length);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(omap_crypto_align_sg);

static void omap_crypto_copy_data(struct scatterlist *src,
                                  struct scatterlist *dst,
                                  int offset, int len)
{
        int amt;
        void *srcb, *dstb;
        int srco = 0, dsto = offset;

        while (src && dst && len) {
                if (srco >= src->length) {
                        srco -= src->length;
                        src = sg_next(src);
                        continue;
                }

                if (dsto >= dst->length) {
                        dsto -= dst->length;
                        dst = sg_next(dst);
                        continue;
                }

                amt = min(src->length - srco, dst->length - dsto);
                amt = min(len, amt);

                srcb = kmap_atomic(sg_page(src)) + srco + src->offset;
                dstb = kmap_atomic(sg_page(dst)) + dsto + dst->offset;

                memcpy(dstb, srcb, amt);

                flush_dcache_page(sg_page(dst));

                kunmap_atomic(srcb);
                kunmap_atomic(dstb);

                srco += amt;
                dsto += amt;
                len -= amt;
        }
}

void omap_crypto_cleanup(struct scatterlist *sg, struct scatterlist *orig,
                         int offset, int len, u8 flags_shift,
                         unsigned long flags)
{
        void *buf;
        int pages;

        flags >>= flags_shift;
        flags &= OMAP_CRYPTO_COPY_MASK;

        if (!flags)
                return;

        buf = sg_virt(sg);
        pages = get_order(len);

        if (orig && (flags & OMAP_CRYPTO_DATA_COPIED))
                omap_crypto_copy_data(sg, orig, offset, len);

        if (flags & OMAP_CRYPTO_DATA_COPIED)
                free_pages((unsigned long)buf, pages);
        else if (flags & OMAP_CRYPTO_SG_COPIED)
                kfree(sg);
}
EXPORT_SYMBOL_GPL(omap_crypto_cleanup);

MODULE_DESCRIPTION("OMAP crypto support library.");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");