From 348fa3f6871f56a37dcd16c99ca98118c6d79a38 Mon Sep 17 00:00:00 2001 From: Dominik Sliwa Date: Mon, 4 Mar 2019 12:01:54 +0100 Subject: Backports v4.19.24 Backports generated by toradex backports 515a1fa55cda2b1d952872e1786857481bd54fcc against mainline kernel tag v4.19.24 Signed-off-by: Dominik Sliwa --- compat/backport-3.11.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 compat/backport-3.11.c (limited to 'compat/backport-3.11.c') diff --git a/compat/backport-3.11.c b/compat/backport-3.11.c new file mode 100644 index 0000000..7f9ff34 --- /dev/null +++ b/compat/backport-3.11.c @@ -0,0 +1,124 @@ +/* + * Copyright (c) 2016 Intel Deutschland GmbH + * + * Backport functionality introduced in Linux 3.11. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include + +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. + */ +static 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; +} + +/** + * 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_GPL(sg_copy_buffer); -- cgit v1.2.3