// 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_array(n, sizeof(*sg), GFP_KERNEL);
  		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.
  ",
  		       __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);

  		if (!PageSlab(sg_page(dst)))
  			flush_kernel_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_COPY_MASK))

  		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>");