|
|
@@ -0,0 +1,202 @@
|
|
|
+/*
|
|
|
+ * Copyright (C) 2015 Robert Jarzmik <robert.jarzmik@free.fr>
|
|
|
+ *
|
|
|
+ * Scatterlist splitting helpers.
|
|
|
+ *
|
|
|
+ * This source code is licensed under the GNU General Public License,
|
|
|
+ * Version 2. See the file COPYING for more details.
|
|
|
+ */
|
|
|
+
|
|
|
+#include <linux/scatterlist.h>
|
|
|
+#include <linux/slab.h>
|
|
|
+
|
|
|
+struct sg_splitter {
|
|
|
+ struct scatterlist *in_sg0;
|
|
|
+ int nents;
|
|
|
+ off_t skip_sg0;
|
|
|
+ unsigned int length_last_sg;
|
|
|
+
|
|
|
+ struct scatterlist *out_sg;
|
|
|
+};
|
|
|
+
|
|
|
+static int sg_calculate_split(struct scatterlist *in, int nents, int nb_splits,
|
|
|
+ off_t skip, const size_t *sizes,
|
|
|
+ struct sg_splitter *splitters, bool mapped)
|
|
|
+{
|
|
|
+ int i;
|
|
|
+ unsigned int sglen;
|
|
|
+ size_t size = sizes[0], len;
|
|
|
+ struct sg_splitter *curr = splitters;
|
|
|
+ struct scatterlist *sg;
|
|
|
+
|
|
|
+ for (i = 0; i < nb_splits; i++) {
|
|
|
+ splitters[i].in_sg0 = NULL;
|
|
|
+ splitters[i].nents = 0;
|
|
|
+ }
|
|
|
+
|
|
|
+ for_each_sg(in, sg, nents, i) {
|
|
|
+ sglen = mapped ? sg_dma_len(sg) : sg->length;
|
|
|
+ if (skip > sglen) {
|
|
|
+ skip -= sglen;
|
|
|
+ continue;
|
|
|
+ }
|
|
|
+
|
|
|
+ len = min_t(size_t, size, sglen - skip);
|
|
|
+ if (!curr->in_sg0) {
|
|
|
+ curr->in_sg0 = sg;
|
|
|
+ curr->skip_sg0 = skip;
|
|
|
+ }
|
|
|
+ size -= len;
|
|
|
+ curr->nents++;
|
|
|
+ curr->length_last_sg = len;
|
|
|
+
|
|
|
+ while (!size && (skip + len < sglen) && (--nb_splits > 0)) {
|
|
|
+ curr++;
|
|
|
+ size = *(++sizes);
|
|
|
+ skip += len;
|
|
|
+ len = min_t(size_t, size, sglen - skip);
|
|
|
+
|
|
|
+ curr->in_sg0 = sg;
|
|
|
+ curr->skip_sg0 = skip;
|
|
|
+ curr->nents = 1;
|
|
|
+ curr->length_last_sg = len;
|
|
|
+ size -= len;
|
|
|
+ }
|
|
|
+ skip = 0;
|
|
|
+
|
|
|
+ if (!size && --nb_splits > 0) {
|
|
|
+ curr++;
|
|
|
+ size = *(++sizes);
|
|
|
+ }
|
|
|
+
|
|
|
+ if (!nb_splits)
|
|
|
+ break;
|
|
|
+ }
|
|
|
+
|
|
|
+ return (size || !splitters[0].in_sg0) ? -EINVAL : 0;
|
|
|
+}
|
|
|
+
|
|
|
+static void sg_split_phys(struct sg_splitter *splitters, const int nb_splits)
|
|
|
+{
|
|
|
+ int i, j;
|
|
|
+ struct scatterlist *in_sg, *out_sg;
|
|
|
+ struct sg_splitter *split;
|
|
|
+
|
|
|
+ for (i = 0, split = splitters; i < nb_splits; i++, split++) {
|
|
|
+ in_sg = split->in_sg0;
|
|
|
+ out_sg = split->out_sg;
|
|
|
+ for (j = 0; j < split->nents; j++, out_sg++) {
|
|
|
+ *out_sg = *in_sg;
|
|
|
+ if (!j) {
|
|
|
+ out_sg->offset += split->skip_sg0;
|
|
|
+ out_sg->length -= split->skip_sg0;
|
|
|
+ } else {
|
|
|
+ out_sg->offset = 0;
|
|
|
+ }
|
|
|
+ sg_dma_address(out_sg) = 0;
|
|
|
+ sg_dma_len(out_sg) = 0;
|
|
|
+ in_sg = sg_next(in_sg);
|
|
|
+ }
|
|
|
+ out_sg[-1].length = split->length_last_sg;
|
|
|
+ sg_mark_end(out_sg - 1);
|
|
|
+ }
|
|
|
+}
|
|
|
+
|
|
|
+static void sg_split_mapped(struct sg_splitter *splitters, const int nb_splits)
|
|
|
+{
|
|
|
+ int i, j;
|
|
|
+ struct scatterlist *in_sg, *out_sg;
|
|
|
+ struct sg_splitter *split;
|
|
|
+
|
|
|
+ for (i = 0, split = splitters; i < nb_splits; i++, split++) {
|
|
|
+ in_sg = split->in_sg0;
|
|
|
+ out_sg = split->out_sg;
|
|
|
+ for (j = 0; j < split->nents; j++, out_sg++) {
|
|
|
+ sg_dma_address(out_sg) = sg_dma_address(in_sg);
|
|
|
+ sg_dma_len(out_sg) = sg_dma_len(in_sg);
|
|
|
+ if (!j) {
|
|
|
+ sg_dma_address(out_sg) += split->skip_sg0;
|
|
|
+ sg_dma_len(out_sg) -= split->skip_sg0;
|
|
|
+ }
|
|
|
+ in_sg = sg_next(in_sg);
|
|
|
+ }
|
|
|
+ sg_dma_len(--out_sg) = split->length_last_sg;
|
|
|
+ }
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * sg_split - split a scatterlist into several scatterlists
|
|
|
+ * @in: the input sg list
|
|
|
+ * @in_mapped_nents: the result of a dma_map_sg(in, ...), or 0 if not mapped.
|
|
|
+ * @skip: the number of bytes to skip in the input sg list
|
|
|
+ * @nb_splits: the number of desired sg outputs
|
|
|
+ * @split_sizes: the respective size of each output sg list in bytes
|
|
|
+ * @out: an array where to store the allocated output sg lists
|
|
|
+ * @out_mapped_nents: the resulting sg lists mapped number of sg entries. Might
|
|
|
+ * be NULL if sglist not already mapped (in_mapped_nents = 0)
|
|
|
+ * @gfp_mask: the allocation flag
|
|
|
+ *
|
|
|
+ * This function splits the input sg list into nb_splits sg lists, which are
|
|
|
+ * allocated and stored into out.
|
|
|
+ * The @in is split into :
|
|
|
+ * - @out[0], which covers bytes [@skip .. @skip + @split_sizes[0] - 1] of @in
|
|
|
+ * - @out[1], which covers bytes [@skip + split_sizes[0] ..
|
|
|
+ * @skip + @split_sizes[0] + @split_sizes[1] -1]
|
|
|
+ * etc ...
|
|
|
+ * It will be the caller's duty to kfree() out array members.
|
|
|
+ *
|
|
|
+ * Returns 0 upon success, or error code
|
|
|
+ */
|
|
|
+int sg_split(struct scatterlist *in, const int in_mapped_nents,
|
|
|
+ const off_t skip, const int nb_splits,
|
|
|
+ const size_t *split_sizes,
|
|
|
+ struct scatterlist **out, int *out_mapped_nents,
|
|
|
+ gfp_t gfp_mask)
|
|
|
+{
|
|
|
+ int i, ret;
|
|
|
+ struct sg_splitter *splitters;
|
|
|
+
|
|
|
+ splitters = kcalloc(nb_splits, sizeof(*splitters), gfp_mask);
|
|
|
+ if (!splitters)
|
|
|
+ return -ENOMEM;
|
|
|
+
|
|
|
+ ret = sg_calculate_split(in, sg_nents(in), nb_splits, skip, split_sizes,
|
|
|
+ splitters, false);
|
|
|
+ if (ret < 0)
|
|
|
+ goto err;
|
|
|
+
|
|
|
+ ret = -ENOMEM;
|
|
|
+ for (i = 0; i < nb_splits; i++) {
|
|
|
+ splitters[i].out_sg = kmalloc_array(splitters[i].nents,
|
|
|
+ sizeof(struct scatterlist),
|
|
|
+ gfp_mask);
|
|
|
+ if (!splitters[i].out_sg)
|
|
|
+ goto err;
|
|
|
+ }
|
|
|
+
|
|
|
+ /*
|
|
|
+ * The order of these 3 calls is important and should be kept.
|
|
|
+ */
|
|
|
+ sg_split_phys(splitters, nb_splits);
|
|
|
+ ret = sg_calculate_split(in, in_mapped_nents, nb_splits, skip,
|
|
|
+ split_sizes, splitters, true);
|
|
|
+ if (ret < 0)
|
|
|
+ goto err;
|
|
|
+ sg_split_mapped(splitters, nb_splits);
|
|
|
+
|
|
|
+ for (i = 0; i < nb_splits; i++) {
|
|
|
+ out[i] = splitters[i].out_sg;
|
|
|
+ if (out_mapped_nents)
|
|
|
+ out_mapped_nents[i] = splitters[i].nents;
|
|
|
+ }
|
|
|
+
|
|
|
+ kfree(splitters);
|
|
|
+ return 0;
|
|
|
+
|
|
|
+err:
|
|
|
+ for (i = 0; i < nb_splits; i++)
|
|
|
+ kfree(splitters[i].out_sg);
|
|
|
+ kfree(splitters);
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+EXPORT_SYMBOL(sg_split);
|
Linus Torvalds