Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 735 insertions, 0 deletions

diff --git a/drivers/mtd/nand/ecc.c b/drivers/mtd/nand/ecc.c
new file mode 100644
index 000000000..6ccdff3fc
--- /dev/null
+++ b/drivers/mtd/nand/ecc.c
@@ -0,0 +1,735 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Generic Error-Correcting Code (ECC) engine
+ *
+ * Copyright (C) 2019 Macronix
+ * Author:
+ *     Miquèl RAYNAL <miquel.raynal@bootlin.com>
+ *
+ *
+ * This file describes the abstraction of any NAND ECC engine. It has been
+ * designed to fit most cases, including parallel NANDs and SPI-NANDs.
+ *
+ * There are three main situations where instantiating this ECC engine makes
+ * sense:
+ *   - external: The ECC engine is outside the NAND pipeline, typically this
+ *               is a software ECC engine, or an hardware engine that is
+ *               outside the NAND controller pipeline.
+ *   - pipelined: The ECC engine is inside the NAND pipeline, ie. on the
+ *                controller's side. This is the case of most of the raw NAND
+ *                controllers. In the pipeline case, the ECC bytes are
+ *                generated/data corrected on the fly when a page is
+ *                written/read.
+ *   - ondie: The ECC engine is inside the NAND pipeline, on the chip's side.
+ *            Some NAND chips can correct themselves the data.
+ *
+ * Besides the initial setup and final cleanups, the interfaces are rather
+ * simple:
+ *   - prepare: Prepare an I/O request. Enable/disable the ECC engine based on
+ *              the I/O request type. In case of software correction or external
+ *              engine, this step may involve to derive the ECC bytes and place
+ *              them in the OOB area before a write.
+ *   - finish: Finish an I/O request. Correct the data in case of a read
+ *             request and report the number of corrected bits/uncorrectable
+ *             errors. Most likely empty for write operations, unless you have
+ *             hardware specific stuff to do, like shutting down the engine to
+ *             save power.
+ *
+ * The I/O request should be enclosed in a prepare()/finish() pair of calls
+ * and will behave differently depending on the requested I/O type:
+ *   - raw: Correction disabled
+ *   - ecc: Correction enabled
+ *
+ * The request direction is impacting the logic as well:
+ *   - read: Load data from the NAND chip
+ *   - write: Store data in the NAND chip
+ *
+ * Mixing all this combinations together gives the following behavior.
+ * Those are just examples, drivers are free to add custom steps in their
+ * prepare/finish hook.
+ *
+ * [external ECC engine]
+ *   - external + prepare + raw + read: do nothing
+ *   - external + finish  + raw + read: do nothing
+ *   - external + prepare + raw + write: do nothing
+ *   - external + finish  + raw + write: do nothing
+ *   - external + prepare + ecc + read: do nothing
+ *   - external + finish  + ecc + read: calculate expected ECC bytes, extract
+ *                                      ECC bytes from OOB buffer, correct
+ *                                      and report any bitflip/error
+ *   - external + prepare + ecc + write: calculate ECC bytes and store them at
+ *                                       the right place in the OOB buffer based
+ *                                       on the OOB layout
+ *   - external + finish  + ecc + write: do nothing
+ *
+ * [pipelined ECC engine]
+ *   - pipelined + prepare + raw + read: disable the controller's ECC engine if
+ *                                       activated
+ *   - pipelined + finish  + raw + read: do nothing
+ *   - pipelined + prepare + raw + write: disable the controller's ECC engine if
+ *                                        activated
+ *   - pipelined + finish  + raw + write: do nothing
+ *   - pipelined + prepare + ecc + read: enable the controller's ECC engine if
+ *                                       deactivated
+ *   - pipelined + finish  + ecc + read: check the status, report any
+ *                                       error/bitflip
+ *   - pipelined + prepare + ecc + write: enable the controller's ECC engine if
+ *                                        deactivated
+ *   - pipelined + finish  + ecc + write: do nothing
+ *
+ * [ondie ECC engine]
+ *   - ondie + prepare + raw + read: send commands to disable the on-chip ECC
+ *                                   engine if activated
+ *   - ondie + finish  + raw + read: do nothing
+ *   - ondie + prepare + raw + write: send commands to disable the on-chip ECC
+ *                                    engine if activated
+ *   - ondie + finish  + raw + write: do nothing
+ *   - ondie + prepare + ecc + read: send commands to enable the on-chip ECC
+ *                                   engine if deactivated
+ *   - ondie + finish  + ecc + read: send commands to check the status, report
+ *                                   any error/bitflip
+ *   - ondie + prepare + ecc + write: send commands to enable the on-chip ECC
+ *                                    engine if deactivated
+ *   - ondie + finish  + ecc + write: do nothing
+ */
+
+#include <linux/module.h>
+#include <linux/mtd/nand.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+
+static LIST_HEAD(on_host_hw_engines);
+static DEFINE_MUTEX(on_host_hw_engines_mutex);
+
+/**
+ * nand_ecc_init_ctx - Init the ECC engine context
+ * @nand: the NAND device
+ *
+ * On success, the caller is responsible of calling @nand_ecc_cleanup_ctx().
+ */
+int nand_ecc_init_ctx(struct nand_device *nand)
+{
+	if (!nand->ecc.engine || !nand->ecc.engine->ops->init_ctx)
+		return 0;
+
+	return nand->ecc.engine->ops->init_ctx(nand);
+}
+EXPORT_SYMBOL(nand_ecc_init_ctx);
+
+/**
+ * nand_ecc_cleanup_ctx - Cleanup the ECC engine context
+ * @nand: the NAND device
+ */
+void nand_ecc_cleanup_ctx(struct nand_device *nand)
+{
+	if (nand->ecc.engine && nand->ecc.engine->ops->cleanup_ctx)
+		nand->ecc.engine->ops->cleanup_ctx(nand);
+}
+EXPORT_SYMBOL(nand_ecc_cleanup_ctx);
+
+/**
+ * nand_ecc_prepare_io_req - Prepare an I/O request
+ * @nand: the NAND device
+ * @req: the I/O request
+ */
+int nand_ecc_prepare_io_req(struct nand_device *nand,
+			    struct nand_page_io_req *req)
+{
+	if (!nand->ecc.engine || !nand->ecc.engine->ops->prepare_io_req)
+		return 0;
+
+	return nand->ecc.engine->ops->prepare_io_req(nand, req);
+}
+EXPORT_SYMBOL(nand_ecc_prepare_io_req);
+
+/**
+ * nand_ecc_finish_io_req - Finish an I/O request
+ * @nand: the NAND device
+ * @req: the I/O request
+ */
+int nand_ecc_finish_io_req(struct nand_device *nand,
+			   struct nand_page_io_req *req)
+{
+	if (!nand->ecc.engine || !nand->ecc.engine->ops->finish_io_req)
+		return 0;
+
+	return nand->ecc.engine->ops->finish_io_req(nand, req);
+}
+EXPORT_SYMBOL(nand_ecc_finish_io_req);
+
+/* Define default OOB placement schemes for large and small page devices */
+static int nand_ooblayout_ecc_sp(struct mtd_info *mtd, int section,
+				 struct mtd_oob_region *oobregion)
+{
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	unsigned int total_ecc_bytes = nand->ecc.ctx.total;
+
+	if (section > 1)
+		return -ERANGE;
+
+	if (!section) {
+		oobregion->offset = 0;
+		if (mtd->oobsize == 16)
+			oobregion->length = 4;
+		else
+			oobregion->length = 3;
+	} else {
+		if (mtd->oobsize == 8)
+			return -ERANGE;
+
+		oobregion->offset = 6;
+		oobregion->length = total_ecc_bytes - 4;
+	}
+
+	return 0;
+}
+
+static int nand_ooblayout_free_sp(struct mtd_info *mtd, int section,
+				  struct mtd_oob_region *oobregion)
+{
+	if (section > 1)
+		return -ERANGE;
+
+	if (mtd->oobsize == 16) {
+		if (section)
+			return -ERANGE;
+
+		oobregion->length = 8;
+		oobregion->offset = 8;
+	} else {
+		oobregion->length = 2;
+		if (!section)
+			oobregion->offset = 3;
+		else
+			oobregion->offset = 6;
+	}
+
+	return 0;
+}
+
+static const struct mtd_ooblayout_ops nand_ooblayout_sp_ops = {
+	.ecc = nand_ooblayout_ecc_sp,
+	.free = nand_ooblayout_free_sp,
+};
+
+const struct mtd_ooblayout_ops *nand_get_small_page_ooblayout(void)
+{
+	return &nand_ooblayout_sp_ops;
+}
+EXPORT_SYMBOL_GPL(nand_get_small_page_ooblayout);
+
+static int nand_ooblayout_ecc_lp(struct mtd_info *mtd, int section,
+				 struct mtd_oob_region *oobregion)
+{
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	unsigned int total_ecc_bytes = nand->ecc.ctx.total;
+
+	if (section || !total_ecc_bytes)
+		return -ERANGE;
+
+	oobregion->length = total_ecc_bytes;
+	oobregion->offset = mtd->oobsize - oobregion->length;
+
+	return 0;
+}
+
+static int nand_ooblayout_free_lp(struct mtd_info *mtd, int section,
+				  struct mtd_oob_region *oobregion)
+{
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	unsigned int total_ecc_bytes = nand->ecc.ctx.total;
+
+	if (section)
+		return -ERANGE;
+
+	oobregion->length = mtd->oobsize - total_ecc_bytes - 2;
+	oobregion->offset = 2;
+
+	return 0;
+}
+
+static const struct mtd_ooblayout_ops nand_ooblayout_lp_ops = {
+	.ecc = nand_ooblayout_ecc_lp,
+	.free = nand_ooblayout_free_lp,
+};
+
+const struct mtd_ooblayout_ops *nand_get_large_page_ooblayout(void)
+{
+	return &nand_ooblayout_lp_ops;
+}
+EXPORT_SYMBOL_GPL(nand_get_large_page_ooblayout);
+
+/*
+ * Support the old "large page" layout used for 1-bit Hamming ECC where ECC
+ * are placed at a fixed offset.
+ */
+static int nand_ooblayout_ecc_lp_hamming(struct mtd_info *mtd, int section,
+					 struct mtd_oob_region *oobregion)
+{
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	unsigned int total_ecc_bytes = nand->ecc.ctx.total;
+
+	if (section)
+		return -ERANGE;
+
+	switch (mtd->oobsize) {
+	case 64:
+		oobregion->offset = 40;
+		break;
+	case 128:
+		oobregion->offset = 80;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	oobregion->length = total_ecc_bytes;
+	if (oobregion->offset + oobregion->length > mtd->oobsize)
+		return -ERANGE;
+
+	return 0;
+}
+
+static int nand_ooblayout_free_lp_hamming(struct mtd_info *mtd, int section,
+					  struct mtd_oob_region *oobregion)
+{
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	unsigned int total_ecc_bytes = nand->ecc.ctx.total;
+	int ecc_offset = 0;
+
+	if (section < 0 || section > 1)
+		return -ERANGE;
+
+	switch (mtd->oobsize) {
+	case 64:
+		ecc_offset = 40;
+		break;
+	case 128:
+		ecc_offset = 80;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (section == 0) {
+		oobregion->offset = 2;
+		oobregion->length = ecc_offset - 2;
+	} else {
+		oobregion->offset = ecc_offset + total_ecc_bytes;
+		oobregion->length = mtd->oobsize - oobregion->offset;
+	}
+
+	return 0;
+}
+
+static const struct mtd_ooblayout_ops nand_ooblayout_lp_hamming_ops = {
+	.ecc = nand_ooblayout_ecc_lp_hamming,
+	.free = nand_ooblayout_free_lp_hamming,
+};
+
+const struct mtd_ooblayout_ops *nand_get_large_page_hamming_ooblayout(void)
+{
+	return &nand_ooblayout_lp_hamming_ops;
+}
+EXPORT_SYMBOL_GPL(nand_get_large_page_hamming_ooblayout);
+
+static enum nand_ecc_engine_type
+of_get_nand_ecc_engine_type(struct device_node *np)
+{
+	struct device_node *eng_np;
+
+	if (of_property_read_bool(np, "nand-no-ecc-engine"))
+		return NAND_ECC_ENGINE_TYPE_NONE;
+
+	if (of_property_read_bool(np, "nand-use-soft-ecc-engine"))
+		return NAND_ECC_ENGINE_TYPE_SOFT;
+
+	eng_np = of_parse_phandle(np, "nand-ecc-engine", 0);
+	of_node_put(eng_np);
+
+	if (eng_np) {
+		if (eng_np == np)
+			return NAND_ECC_ENGINE_TYPE_ON_DIE;
+		else
+			return NAND_ECC_ENGINE_TYPE_ON_HOST;
+	}
+
+	return NAND_ECC_ENGINE_TYPE_INVALID;
+}
+
+static const char * const nand_ecc_placement[] = {
+	[NAND_ECC_PLACEMENT_OOB] = "oob",
+	[NAND_ECC_PLACEMENT_INTERLEAVED] = "interleaved",
+};
+
+static enum nand_ecc_placement of_get_nand_ecc_placement(struct device_node *np)
+{
+	enum nand_ecc_placement placement;
+	const char *pm;
+	int err;
+
+	err = of_property_read_string(np, "nand-ecc-placement", &pm);
+	if (!err) {
+		for (placement = NAND_ECC_PLACEMENT_OOB;
+		     placement < ARRAY_SIZE(nand_ecc_placement); placement++) {
+			if (!strcasecmp(pm, nand_ecc_placement[placement]))
+				return placement;
+		}
+	}
+
+	return NAND_ECC_PLACEMENT_UNKNOWN;
+}
+
+static const char * const nand_ecc_algos[] = {
+	[NAND_ECC_ALGO_HAMMING] = "hamming",
+	[NAND_ECC_ALGO_BCH] = "bch",
+	[NAND_ECC_ALGO_RS] = "rs",
+};
+
+static enum nand_ecc_algo of_get_nand_ecc_algo(struct device_node *np)
+{
+	enum nand_ecc_algo ecc_algo;
+	const char *pm;
+	int err;
+
+	err = of_property_read_string(np, "nand-ecc-algo", &pm);
+	if (!err) {
+		for (ecc_algo = NAND_ECC_ALGO_HAMMING;
+		     ecc_algo < ARRAY_SIZE(nand_ecc_algos);
+		     ecc_algo++) {
+			if (!strcasecmp(pm, nand_ecc_algos[ecc_algo]))
+				return ecc_algo;
+		}
+	}
+
+	return NAND_ECC_ALGO_UNKNOWN;
+}
+
+static int of_get_nand_ecc_step_size(struct device_node *np)
+{
+	int ret;
+	u32 val;
+
+	ret = of_property_read_u32(np, "nand-ecc-step-size", &val);
+	return ret ? ret : val;
+}
+
+static int of_get_nand_ecc_strength(struct device_node *np)
+{
+	int ret;
+	u32 val;
+
+	ret = of_property_read_u32(np, "nand-ecc-strength", &val);
+	return ret ? ret : val;
+}
+
+void of_get_nand_ecc_user_config(struct nand_device *nand)
+{
+	struct device_node *dn = nanddev_get_of_node(nand);
+	int strength, size;
+
+	nand->ecc.user_conf.engine_type = of_get_nand_ecc_engine_type(dn);
+	nand->ecc.user_conf.algo = of_get_nand_ecc_algo(dn);
+	nand->ecc.user_conf.placement = of_get_nand_ecc_placement(dn);
+
+	strength = of_get_nand_ecc_strength(dn);
+	if (strength >= 0)
+		nand->ecc.user_conf.strength = strength;
+
+	size = of_get_nand_ecc_step_size(dn);
+	if (size >= 0)
+		nand->ecc.user_conf.step_size = size;
+
+	if (of_property_read_bool(dn, "nand-ecc-maximize"))
+		nand->ecc.user_conf.flags |= NAND_ECC_MAXIMIZE_STRENGTH;
+}
+EXPORT_SYMBOL(of_get_nand_ecc_user_config);
+
+/**
+ * nand_ecc_is_strong_enough - Check if the chip configuration meets the
+ *                             datasheet requirements.
+ *
+ * @nand: Device to check
+ *
+ * If our configuration corrects A bits per B bytes and the minimum
+ * required correction level is X bits per Y bytes, then we must ensure
+ * both of the following are true:
+ *
+ * (1) A / B >= X / Y
+ * (2) A >= X
+ *
+ * Requirement (1) ensures we can correct for the required bitflip density.
+ * Requirement (2) ensures we can correct even when all bitflips are clumped
+ * in the same sector.
+ */
+bool nand_ecc_is_strong_enough(struct nand_device *nand)
+{
+	const struct nand_ecc_props *reqs = nanddev_get_ecc_requirements(nand);
+	const struct nand_ecc_props *conf = nanddev_get_ecc_conf(nand);
+	struct mtd_info *mtd = nanddev_to_mtd(nand);
+	int corr, ds_corr;
+
+	if (conf->step_size == 0 || reqs->step_size == 0)
+		/* Not enough information */
+		return true;
+
+	/*
+	 * We get the number of corrected bits per page to compare
+	 * the correction density.
+	 */
+	corr = (mtd->writesize * conf->strength) / conf->step_size;
+	ds_corr = (mtd->writesize * reqs->strength) / reqs->step_size;
+
+	return corr >= ds_corr && conf->strength >= reqs->strength;
+}
+EXPORT_SYMBOL(nand_ecc_is_strong_enough);
+
+/* ECC engine driver internal helpers */
+int nand_ecc_init_req_tweaking(struct nand_ecc_req_tweak_ctx *ctx,
+			       struct nand_device *nand)
+{
+	unsigned int total_buffer_size;
+
+	ctx->nand = nand;
+
+	/* Let the user decide the exact length of each buffer */
+	if (!ctx->page_buffer_size)
+		ctx->page_buffer_size = nanddev_page_size(nand);
+	if (!ctx->oob_buffer_size)
+		ctx->oob_buffer_size = nanddev_per_page_oobsize(nand);
+
+	total_buffer_size = ctx->page_buffer_size + ctx->oob_buffer_size;
+
+	ctx->spare_databuf = kzalloc(total_buffer_size, GFP_KERNEL);
+	if (!ctx->spare_databuf)
+		return -ENOMEM;
+
+	ctx->spare_oobbuf = ctx->spare_databuf + ctx->page_buffer_size;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nand_ecc_init_req_tweaking);
+
+void nand_ecc_cleanup_req_tweaking(struct nand_ecc_req_tweak_ctx *ctx)
+{
+	kfree(ctx->spare_databuf);
+}
+EXPORT_SYMBOL_GPL(nand_ecc_cleanup_req_tweaking);
+
+/*
+ * Ensure data and OOB area is fully read/written otherwise the correction might
+ * not work as expected.
+ */
+void nand_ecc_tweak_req(struct nand_ecc_req_tweak_ctx *ctx,
+			struct nand_page_io_req *req)
+{
+	struct nand_device *nand = ctx->nand;
+	struct nand_page_io_req *orig, *tweak;
+
+	/* Save the original request */
+	ctx->orig_req = *req;
+	ctx->bounce_data = false;
+	ctx->bounce_oob = false;
+	orig = &ctx->orig_req;
+	tweak = req;
+
+	/* Ensure the request covers the entire page */
+	if (orig->datalen < nanddev_page_size(nand)) {
+		ctx->bounce_data = true;
+		tweak->dataoffs = 0;
+		tweak->datalen = nanddev_page_size(nand);
+		tweak->databuf.in = ctx->spare_databuf;
+		memset(tweak->databuf.in, 0xFF, ctx->page_buffer_size);
+	}
+
+	if (orig->ooblen < nanddev_per_page_oobsize(nand)) {
+		ctx->bounce_oob = true;
+		tweak->ooboffs = 0;
+		tweak->ooblen = nanddev_per_page_oobsize(nand);
+		tweak->oobbuf.in = ctx->spare_oobbuf;
+		memset(tweak->oobbuf.in, 0xFF, ctx->oob_buffer_size);
+	}
+
+	/* Copy the data that must be written in the bounce buffers, if needed */
+	if (orig->type == NAND_PAGE_WRITE) {
+		if (ctx->bounce_data)
+			memcpy((void *)tweak->databuf.out + orig->dataoffs,
+			       orig->databuf.out, orig->datalen);
+
+		if (ctx->bounce_oob)
+			memcpy((void *)tweak->oobbuf.out + orig->ooboffs,
+			       orig->oobbuf.out, orig->ooblen);
+	}
+}
+EXPORT_SYMBOL_GPL(nand_ecc_tweak_req);
+
+void nand_ecc_restore_req(struct nand_ecc_req_tweak_ctx *ctx,
+			  struct nand_page_io_req *req)
+{
+	struct nand_page_io_req *orig, *tweak;
+
+	orig = &ctx->orig_req;
+	tweak = req;
+
+	/* Restore the data read from the bounce buffers, if needed */
+	if (orig->type == NAND_PAGE_READ) {
+		if (ctx->bounce_data)
+			memcpy(orig->databuf.in,
+			       tweak->databuf.in + orig->dataoffs,
+			       orig->datalen);
+
+		if (ctx->bounce_oob)
+			memcpy(orig->oobbuf.in,
+			       tweak->oobbuf.in + orig->ooboffs,
+			       orig->ooblen);
+	}
+
+	/* Ensure the original request is restored */
+	*req = *orig;
+}
+EXPORT_SYMBOL_GPL(nand_ecc_restore_req);
+
+struct nand_ecc_engine *nand_ecc_get_sw_engine(struct nand_device *nand)
+{
+	unsigned int algo = nand->ecc.user_conf.algo;
+
+	if (algo == NAND_ECC_ALGO_UNKNOWN)
+		algo = nand->ecc.defaults.algo;
+
+	switch (algo) {
+	case NAND_ECC_ALGO_HAMMING:
+		return nand_ecc_sw_hamming_get_engine();
+	case NAND_ECC_ALGO_BCH:
+		return nand_ecc_sw_bch_get_engine();
+	default:
+		break;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(nand_ecc_get_sw_engine);
+
+struct nand_ecc_engine *nand_ecc_get_on_die_hw_engine(struct nand_device *nand)
+{
+	return nand->ecc.ondie_engine;
+}
+EXPORT_SYMBOL(nand_ecc_get_on_die_hw_engine);
+
+int nand_ecc_register_on_host_hw_engine(struct nand_ecc_engine *engine)
+{
+	struct nand_ecc_engine *item;
+
+	if (!engine)
+		return -EINVAL;
+
+	/* Prevent multiple registrations of one engine */
+	list_for_each_entry(item, &on_host_hw_engines, node)
+		if (item == engine)
+			return 0;
+
+	mutex_lock(&on_host_hw_engines_mutex);
+	list_add_tail(&engine->node, &on_host_hw_engines);
+	mutex_unlock(&on_host_hw_engines_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL(nand_ecc_register_on_host_hw_engine);
+
+int nand_ecc_unregister_on_host_hw_engine(struct nand_ecc_engine *engine)
+{
+	if (!engine)
+		return -EINVAL;
+
+	mutex_lock(&on_host_hw_engines_mutex);
+	list_del(&engine->node);
+	mutex_unlock(&on_host_hw_engines_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL(nand_ecc_unregister_on_host_hw_engine);
+
+static struct nand_ecc_engine *nand_ecc_match_on_host_hw_engine(struct device *dev)
+{
+	struct nand_ecc_engine *item;
+
+	list_for_each_entry(item, &on_host_hw_engines, node)
+		if (item->dev == dev)
+			return item;
+
+	return NULL;
+}
+
+struct nand_ecc_engine *nand_ecc_get_on_host_hw_engine(struct nand_device *nand)
+{
+	struct nand_ecc_engine *engine = NULL;
+	struct device *dev = &nand->mtd.dev;
+	struct platform_device *pdev;
+	struct device_node *np;
+
+	if (list_empty(&on_host_hw_engines))
+		return NULL;
+
+	/* Check for an explicit nand-ecc-engine property */
+	np = of_parse_phandle(dev->of_node, "nand-ecc-engine", 0);
+	if (np) {
+		pdev = of_find_device_by_node(np);
+		if (!pdev)
+			return ERR_PTR(-EPROBE_DEFER);
+
+		engine = nand_ecc_match_on_host_hw_engine(&pdev->dev);
+		platform_device_put(pdev);
+		of_node_put(np);
+
+		if (!engine)
+			return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	if (engine)
+		get_device(engine->dev);
+
+	return engine;
+}
+EXPORT_SYMBOL(nand_ecc_get_on_host_hw_engine);
+
+void nand_ecc_put_on_host_hw_engine(struct nand_device *nand)
+{
+	put_device(nand->ecc.engine->dev);
+}
+EXPORT_SYMBOL(nand_ecc_put_on_host_hw_engine);
+
+/*
+ * In the case of a pipelined engine, the device registering the ECC
+ * engine is not necessarily the ECC engine itself but may be a host controller.
+ * It is then useful to provide a helper to retrieve the right device object
+ * which actually represents the ECC engine.
+ */
+struct device *nand_ecc_get_engine_dev(struct device *host)
+{
+	struct platform_device *ecc_pdev;
+	struct device_node *np;
+
+	/*
+	 * If the device node contains this property, it means we need to follow
+	 * it in order to get the right ECC engine device we are looking for.
+	 */
+	np = of_parse_phandle(host->of_node, "nand-ecc-engine", 0);
+	if (!np)
+		return host;
+
+	ecc_pdev = of_find_device_by_node(np);
+	if (!ecc_pdev) {
+		of_node_put(np);
+		return NULL;
+	}
+
+	platform_device_put(ecc_pdev);
+	of_node_put(np);
+
+	return &ecc_pdev->dev;
+}
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Miquel Raynal <miquel.raynal@bootlin.com>");
+MODULE_DESCRIPTION("Generic ECC engine");