WebSVN – Kolibri OS – Diff – /drivers/ddk/linux/scatterlist.c

 		nents++;
 	return nents;
+}
 EXPORT_SYMBOL(sg_nents);
+/**
+ * sg_nents_for_len - return total count of entries in scatterlist
+ *                    needed to satisfy the supplied length
+ * @sg:		The scatterlist
+ * @len:	The total required length
+ *
+ * Description:
+ * Determines the number of entries in sg that are required to meet
+ * the supplied length, taking into acount chaining as well
+ *
+ * Returns:
+ *   the number of sg entries needed, negative error on failure
+ *
+ **/
+int sg_nents_for_len(struct scatterlist *sg, u64 len)
+{
+	int nents;
+	u64 total;
+	if (!len)
+		return 0;
+	for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
+		nents++;
+		total += sg->length;
+		if (total >= len)
+			return nents;
+	}
+	return -EINVAL;
+}
 EXPORT_SYMBOL(sg_nents_for_len);
 /**
  * sg_last - return the last scatterlist entry in a list
  *   exist from @sgl@.
+ *
  **/
 struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
+{
-#ifndef CONFIG_ARCH_HAS_SG_CHAIN
-	struct scatterlist *ret = &sgl[nents - 1];
-#else
 	struct scatterlist *sg, *ret = NULL;
 	unsigned int i;
 	for_each_sg(sgl, sg, nents, i)
-		ret = sg;
 		ret = sg;
 #endif
 #ifdef CONFIG_DEBUG_SG
 	BUG_ON(sgl[0].sg_magic != SG_MAGIC);
 	BUG_ON(!sg_is_last(ret));
-    return true;
+	return true;
+}
+EXPORT_SYMBOL(__sg_page_iter_next);
+/**
+ * sg_miter_start - start mapping iteration over a sg list
+ * @miter: sg mapping iter to be started
+ * @sgl: sg list to iterate over
+ * @nents: number of sg entries
+ *
+ * Description:
+ *   Starts mapping iterator @miter.
+ *
+ * Context:
+ *   Don't care.
+ */
+void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
+		    unsigned int nents, unsigned int flags)
+{
+	memset(miter, 0, sizeof(struct sg_mapping_iter));
+	__sg_page_iter_start(&miter->piter, sgl, nents, 0);
+	WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
+	miter->__flags = flags;
+}
+EXPORT_SYMBOL(sg_miter_start);
+static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
+{
+	if (!miter->__remaining) {
+		struct scatterlist *sg;
+		unsigned long pgoffset;
+		if (!__sg_page_iter_next(&miter->piter))
+			return false;
+		sg = miter->piter.sg;
+		pgoffset = miter->piter.sg_pgoffset;
+		miter->__offset = pgoffset ? 0 : sg->offset;
+		miter->__remaining = sg->offset + sg->length -
+				(pgoffset << PAGE_SHIFT) - miter->__offset;
+		miter->__remaining = min_t(unsigned long, miter->__remaining,
+					   PAGE_SIZE - miter->__offset);
+	}
+	return true;
+}
+/**
+ * sg_miter_skip - reposition mapping iterator
+ * @miter: sg mapping iter to be skipped
+ * @offset: number of bytes to plus the current location
+ *
+ * Description:
+ *   Sets the offset of @miter to its current location plus @offset bytes.
+ *   If mapping iterator @miter has been proceeded by sg_miter_next(), this
+ *   stops @miter.
+ *
+ * Context:
+ *   Don't care if @miter is stopped, or not proceeded yet.
+ *   Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
+ *
+ * Returns:
+ *   true if @miter contains the valid mapping.  false if end of sg
+ *   list is reached.
+ */
+bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
+{
+	sg_miter_stop(miter);
+	while (offset) {
+		off_t consumed;
+		if (!sg_miter_get_next_page(miter))
+			return false;
+		consumed = min_t(off_t, offset, miter->__remaining);
+		miter->__offset += consumed;
+		miter->__remaining -= consumed;
+		offset -= consumed;
+	}
+	return true;
+}
+EXPORT_SYMBOL(sg_miter_skip);
+/**
+ * sg_miter_next - proceed mapping iterator to the next mapping
+ * @miter: sg mapping iter to proceed
+ *
+ * Description:
+ *   Proceeds @miter to the next mapping.  @miter should have been started
+ *   using sg_miter_start().  On successful return, @miter->page,
+ *   @miter->addr and @miter->length point to the current mapping.
+ *
+ * Context:
+ *   Preemption disabled if SG_MITER_ATOMIC.  Preemption must stay disabled
+ *   till @miter is stopped.  May sleep if !SG_MITER_ATOMIC.
+ *
+ * Returns:
+ *   true if @miter contains the next mapping.  false if end of sg
+ *   list is reached.
+ */
+bool sg_miter_next(struct sg_mapping_iter *miter)
+{
+	sg_miter_stop(miter);
+	/*
+	 * Get to the next page if necessary.
+	 * __remaining, __offset is adjusted by sg_miter_stop
+	 */
+	if (!sg_miter_get_next_page(miter))
+		return false;
+	miter->page = sg_page_iter_page(&miter->piter);
+	miter->consumed = miter->length = miter->__remaining;
+	if (miter->__flags & SG_MITER_ATOMIC)
+		miter->addr = kmap_atomic(miter->page) + miter->__offset;
+	else
+		miter->addr = kmap(miter->page) + miter->__offset;
+	return true;
+}
+EXPORT_SYMBOL(sg_miter_next);
+/**
+ * sg_miter_stop - stop mapping iteration
+ * @miter: sg mapping iter to be stopped
+ *
+ * Description:
+ *   Stops mapping iterator @miter.  @miter should have been started
+ *   started using sg_miter_start().  A stopped iteration can be
+ *   resumed by calling sg_miter_next() on it.  This is useful when
+ *   resources (kmap) need to be released during iteration.
+ *
+ * Context:
+ *   Preemption disabled if the SG_MITER_ATOMIC is set.  Don't care
+ *   otherwise.
+ */
+void sg_miter_stop(struct sg_mapping_iter *miter)
+{
+	WARN_ON(miter->consumed > miter->length);
+	/* drop resources from the last iteration */
+	if (miter->addr) {
+		miter->__offset += miter->consumed;
+		miter->__remaining -= miter->consumed;
+		if (miter->__flags & SG_MITER_ATOMIC) {
+			WARN_ON_ONCE(preemptible());
+			kunmap_atomic(miter->addr);
+		} else
+			kunmap(miter->page);
+		miter->page = NULL;
+		miter->addr = NULL;
+		miter->length = 0;
+		miter->consumed = 0;
+	}
+}
+EXPORT_SYMBOL(sg_miter_stop);
+/**
+ * sg_copy_buffer - Copy data between a linear buffer and an SG list
+ * @sgl:		 The SG list
+ * @nents:		 Number of SG entries
+ * @buf:		 Where to copy from
+ * @buflen:		 The number of bytes to copy
+ * @skip:		 Number of bytes to skip before copying
+ * @to_buffer:		 transfer direction (true == from an sg list to a
+ *			 buffer, false == from a buffer to an sg list
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
+		      size_t buflen, off_t skip, bool to_buffer)
+{
+	unsigned int offset = 0;
+	struct sg_mapping_iter miter;
+	unsigned long flags;
+	unsigned int sg_flags = SG_MITER_ATOMIC;
+	if (to_buffer)
+		sg_flags |= SG_MITER_FROM_SG;
+	else
+		sg_flags |= SG_MITER_TO_SG;
+	sg_miter_start(&miter, sgl, nents, sg_flags);
+	if (!sg_miter_skip(&miter, skip))
+		return false;
+	local_irq_save(flags);
+	while (sg_miter_next(&miter) && offset < buflen) {
+		unsigned int len;
+		len = min(miter.length, buflen - offset);
+		if (to_buffer)
+			memcpy(buf + offset, miter.addr, len);
+		else
+			memcpy(miter.addr, buf + offset, len);
+		offset += len;
+	}
+	sg_miter_stop(&miter);
+	local_irq_restore(flags);
+	return offset;
+}
+EXPORT_SYMBOL(sg_copy_buffer);
+/**
+ * sg_copy_from_buffer - Copy from a linear buffer to an SG list
+ * @sgl:		 The SG list
+ * @nents:		 Number of SG entries
+ * @buf:		 Where to copy from
+ * @buflen:		 The number of bytes to copy
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
+			   const void *buf, size_t buflen)
+{
+	return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
+}
+EXPORT_SYMBOL(sg_copy_from_buffer);
+/**
+ * sg_copy_to_buffer - Copy from an SG list to a linear buffer
+ * @sgl:		 The SG list
+ * @nents:		 Number of SG entries
+ * @buf:		 Where to copy to
+ * @buflen:		 The number of bytes to copy
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
+			 void *buf, size_t buflen)
+{
+	return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
+}
+EXPORT_SYMBOL(sg_copy_to_buffer);
+/**
+ * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
+ * @sgl:		 The SG list
+ * @nents:		 Number of SG entries
+ * @buf:		 Where to copy from
+ * @buflen:		 The number of bytes to copy
+ * @skip:		 Number of bytes to skip before copying
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
+			    const void *buf, size_t buflen, off_t skip)
+{
+	return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
+}
+EXPORT_SYMBOL(sg_pcopy_from_buffer);
+/**
+ * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
+ * @sgl:		 The SG list
+ * @nents:		 Number of SG entries
+ * @buf:		 Where to copy to
+ * @buflen:		 The number of bytes to copy
+ * @skip:		 Number of bytes to skip before copying
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
+			  void *buf, size_t buflen, off_t skip)

Subversion Repositories Kolibri OS

(root)/drivers/ddk/linux/scatterlist.c – Rev 5270 → 6082