zte's code,first commit
Change-Id: I9a04da59e459a9bc0d67f101f700d9d7dc8d681b
diff --git a/ap/os/linux/linux-3.4.x/lib/scatterlist.c b/ap/os/linux/linux-3.4.x/lib/scatterlist.c
new file mode 100644
index 0000000..4f9d72a
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/lib/scatterlist.c
@@ -0,0 +1,520 @@
+/*
+ * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
+ *
+ * Scatterlist handling helpers.
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/scatterlist.h>
+#include <linux/highmem.h>
+#include <linux/kmemleak.h>
+
+/**
+ * sg_next - return the next scatterlist entry in a list
+ * @sg: The current sg entry
+ *
+ * Description:
+ * Usually the next entry will be @sg@ + 1, but if this sg element is part
+ * of a chained scatterlist, it could jump to the start of a new
+ * scatterlist array.
+ *
+ **/
+struct scatterlist *sg_next(struct scatterlist *sg)
+{
+#ifdef CONFIG_DEBUG_SG
+ BUG_ON(sg->sg_magic != SG_MAGIC);
+#endif
+ if (sg_is_last(sg))
+ return NULL;
+
+ sg++;
+ if (unlikely(sg_is_chain(sg)))
+ sg = sg_chain_ptr(sg);
+
+ return sg;
+}
+EXPORT_SYMBOL(sg_next);
+
+/**
+ * sg_last - return the last scatterlist entry in a list
+ * @sgl: First entry in the scatterlist
+ * @nents: Number of entries in the scatterlist
+ *
+ * Description:
+ * Should only be used casually, it (currently) scans the entire list
+ * to get the last entry.
+ *
+ * Note that the @sgl@ pointer passed in need not be the first one,
+ * the important bit is that @nents@ denotes the number of entries that
+ * exist from @sgl@.
+ *
+ **/
+struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
+{
+#ifndef 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;
+
+#endif
+#ifdef CONFIG_DEBUG_SG
+ BUG_ON(sgl[0].sg_magic != SG_MAGIC);
+ BUG_ON(!sg_is_last(ret));
+#endif
+ return ret;
+}
+EXPORT_SYMBOL(sg_last);
+
+/**
+ * sg_init_table - Initialize SG table
+ * @sgl: The SG table
+ * @nents: Number of entries in table
+ *
+ * Notes:
+ * If this is part of a chained sg table, sg_mark_end() should be
+ * used only on the last table part.
+ *
+ **/
+void sg_init_table(struct scatterlist *sgl, unsigned int nents)
+{
+ memset(sgl, 0, sizeof(*sgl) * nents);
+#ifdef CONFIG_DEBUG_SG
+ {
+ unsigned int i;
+ for (i = 0; i < nents; i++)
+ sgl[i].sg_magic = SG_MAGIC;
+ }
+#endif
+ sg_mark_end(&sgl[nents - 1]);
+}
+EXPORT_SYMBOL(sg_init_table);
+
+/**
+ * sg_init_one - Initialize a single entry sg list
+ * @sg: SG entry
+ * @buf: Virtual address for IO
+ * @buflen: IO length
+ *
+ **/
+void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
+{
+ sg_init_table(sg, 1);
+ sg_set_buf(sg, buf, buflen);
+}
+EXPORT_SYMBOL(sg_init_one);
+
+/*
+ * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
+ * helpers.
+ */
+static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
+{
+ if (nents == SG_MAX_SINGLE_ALLOC) {
+ /*
+ * Kmemleak doesn't track page allocations as they are not
+ * commonly used (in a raw form) for kernel data structures.
+ * As we chain together a list of pages and then a normal
+ * kmalloc (tracked by kmemleak), in order to for that last
+ * allocation not to become decoupled (and thus a
+ * false-positive) we need to inform kmemleak of all the
+ * intermediate allocations.
+ */
+ void *ptr = (void *) __get_free_page(gfp_mask);
+ kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
+ return ptr;
+ } else
+ return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
+}
+
+static void sg_kfree(struct scatterlist *sg, unsigned int nents)
+{
+ if (nents == SG_MAX_SINGLE_ALLOC) {
+ kmemleak_free(sg);
+ free_page((unsigned long) sg);
+ } else
+ kfree(sg);
+}
+
+/**
+ * __sg_free_table - Free a previously mapped sg table
+ * @table: The sg table header to use
+ * @max_ents: The maximum number of entries per single scatterlist
+ * @free_fn: Free function
+ *
+ * Description:
+ * Free an sg table previously allocated and setup with
+ * __sg_alloc_table(). The @max_ents value must be identical to
+ * that previously used with __sg_alloc_table().
+ *
+ **/
+void __sg_free_table(struct sg_table *table, unsigned int max_ents,
+ sg_free_fn *free_fn)
+{
+ struct scatterlist *sgl, *next;
+
+ if (unlikely(!table->sgl))
+ return;
+
+ sgl = table->sgl;
+ while (table->orig_nents) {
+ unsigned int alloc_size = table->orig_nents;
+ unsigned int sg_size;
+
+ /*
+ * If we have more than max_ents segments left,
+ * then assign 'next' to the sg table after the current one.
+ * sg_size is then one less than alloc size, since the last
+ * element is the chain pointer.
+ */
+ if (alloc_size > max_ents) {
+ next = sg_chain_ptr(&sgl[max_ents - 1]);
+ alloc_size = max_ents;
+ sg_size = alloc_size - 1;
+ } else {
+ sg_size = alloc_size;
+ next = NULL;
+ }
+
+ table->orig_nents -= sg_size;
+ free_fn(sgl, alloc_size);
+ sgl = next;
+ }
+
+ table->sgl = NULL;
+}
+EXPORT_SYMBOL(__sg_free_table);
+
+/**
+ * sg_free_table - Free a previously allocated sg table
+ * @table: The mapped sg table header
+ *
+ **/
+void sg_free_table(struct sg_table *table)
+{
+ __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree);
+}
+EXPORT_SYMBOL(sg_free_table);
+
+/**
+ * __sg_alloc_table - Allocate and initialize an sg table with given allocator
+ * @table: The sg table header to use
+ * @nents: Number of entries in sg list
+ * @max_ents: The maximum number of entries the allocator returns per call
+ * @gfp_mask: GFP allocation mask
+ * @alloc_fn: Allocator to use
+ *
+ * Description:
+ * This function returns a @table @nents long. The allocator is
+ * defined to return scatterlist chunks of maximum size @max_ents.
+ * Thus if @nents is bigger than @max_ents, the scatterlists will be
+ * chained in units of @max_ents.
+ *
+ * Notes:
+ * If this function returns non-0 (eg failure), the caller must call
+ * __sg_free_table() to cleanup any leftover allocations.
+ *
+ **/
+int __sg_alloc_table(struct sg_table *table, unsigned int nents,
+ unsigned int max_ents, gfp_t gfp_mask,
+ sg_alloc_fn *alloc_fn)
+{
+ struct scatterlist *sg, *prv;
+ unsigned int left;
+
+#ifndef ARCH_HAS_SG_CHAIN
+ BUG_ON(nents > max_ents);
+#endif
+
+ memset(table, 0, sizeof(*table));
+
+ left = nents;
+ prv = NULL;
+ do {
+ unsigned int sg_size, alloc_size = left;
+
+ if (alloc_size > max_ents) {
+ alloc_size = max_ents;
+ sg_size = alloc_size - 1;
+ } else
+ sg_size = alloc_size;
+
+ left -= sg_size;
+
+ sg = alloc_fn(alloc_size, gfp_mask);
+ if (unlikely(!sg)) {
+ /*
+ * Adjust entry count to reflect that the last
+ * entry of the previous table won't be used for
+ * linkage. Without this, sg_kfree() may get
+ * confused.
+ */
+ if (prv)
+ table->nents = ++table->orig_nents;
+
+ return -ENOMEM;
+ }
+
+ sg_init_table(sg, alloc_size);
+ table->nents = table->orig_nents += sg_size;
+
+ /*
+ * If this is the first mapping, assign the sg table header.
+ * If this is not the first mapping, chain previous part.
+ */
+ if (prv)
+ sg_chain(prv, max_ents, sg);
+ else
+ table->sgl = sg;
+
+ /*
+ * If no more entries after this one, mark the end
+ */
+ if (!left)
+ sg_mark_end(&sg[sg_size - 1]);
+
+ /*
+ * only really needed for mempool backed sg allocations (like
+ * SCSI), a possible improvement here would be to pass the
+ * table pointer into the allocator and let that clear these
+ * flags
+ */
+ gfp_mask &= ~__GFP_WAIT;
+ gfp_mask |= __GFP_HIGH;
+ prv = sg;
+ } while (left);
+
+ return 0;
+}
+EXPORT_SYMBOL(__sg_alloc_table);
+
+/**
+ * sg_alloc_table - Allocate and initialize an sg table
+ * @table: The sg table header to use
+ * @nents: Number of entries in sg list
+ * @gfp_mask: GFP allocation mask
+ *
+ * Description:
+ * Allocate and initialize an sg table. If @nents@ is larger than
+ * SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
+ *
+ **/
+int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
+{
+ int ret;
+
+ ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
+ gfp_mask, sg_kmalloc);
+ if (unlikely(ret))
+ __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree);
+
+ return ret;
+}
+EXPORT_SYMBOL(sg_alloc_table);
+
+/**
+ * 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));
+
+ miter->__sg = sgl;
+ miter->__nents = nents;
+ miter->__offset = 0;
+ WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
+ miter->__flags = flags;
+}
+EXPORT_SYMBOL(sg_miter_start);
+
+/**
+ * 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:
+ * IRQ disabled if SG_MITER_ATOMIC. IRQ 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)
+{
+ unsigned int off, len;
+
+ /* check for end and drop resources from the last iteration */
+ if (!miter->__nents)
+ return false;
+
+ sg_miter_stop(miter);
+
+ /* get to the next sg if necessary. __offset is adjusted by stop */
+ while (miter->__offset == miter->__sg->length) {
+ if (--miter->__nents) {
+ miter->__sg = sg_next(miter->__sg);
+ miter->__offset = 0;
+ } else
+ return false;
+ }
+
+ /* map the next page */
+ off = miter->__sg->offset + miter->__offset;
+ len = miter->__sg->length - miter->__offset;
+
+ miter->page = nth_page(sg_page(miter->__sg), off >> PAGE_SHIFT);
+ off &= ~PAGE_MASK;
+ miter->length = min_t(unsigned int, len, PAGE_SIZE - off);
+ miter->consumed = miter->length;
+
+ if (miter->__flags & SG_MITER_ATOMIC)
+ miter->addr = kmap_atomic(miter->page) + off;
+ else
+ miter->addr = kmap(miter->page) + off;
+
+ 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:
+ * IRQ 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;
+
+ if ((miter->__flags & SG_MITER_TO_SG) &&
+ !PageSlab(miter->page))
+ flush_kernel_dcache_page(miter->page);
+
+ if (miter->__flags & SG_MITER_ATOMIC) {
+ WARN_ON_NONRT(!irqs_disabled());
+ 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
+ * @to_buffer: transfer direction (non zero == from an sg list to a
+ * buffer, 0 == from a buffer to an sg list
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen, int 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);
+
+ local_irq_save_nort(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_nort(flags);
+ return offset;
+}
+
+/**
+ * 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,
+ void *buf, size_t buflen)
+{
+ return sg_copy_buffer(sgl, nents, buf, buflen, 0);
+}
+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, 1);
+}
+EXPORT_SYMBOL(sg_copy_to_buffer);