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mtd: nand: ecc: Add an I/O request tweaking mechanism

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Currently, BCH and Hamming engine are sharing the same
tweaking/restoring I/O mechanism: they need the I/O request to fully
cover the main/OOB area. Let's make this code generic as sharing the
code between two drivers is already a win. Maybe other ECC engine
drivers will need it too.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200929230124.31491-2-miquel.raynal@bootlin.com
This commit is contained in:
Miquel Raynal 2020-09-30 01:01:05 +02:00
parent b650545978
commit 51e7bf4534
2 changed files with 138 additions and 0 deletions
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106
drivers/mtd/nand/ecc.c
View File

@ -95,6 +95,7 @@
#include <linux/module.h>
#include <linux/mtd/nand.h>
#include <linux/slab.h>
/**
* nand_ecc_init_ctx - Init the ECC engine context
@ -479,6 +480,111 @@ bool nand_ecc_is_strong_enough(struct nand_device *nand)
}
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 writen 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);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Miquel Raynal <miquel.raynal@bootlin.com>");
MODULE_DESCRIPTION("Generic ECC engine");

32
include/linux/mtd/nand.h
View File

@ -278,6 +278,38 @@ int nand_ecc_finish_io_req(struct nand_device *nand,
struct nand_page_io_req *req);
bool nand_ecc_is_strong_enough(struct nand_device *nand);
/**
* struct nand_ecc_req_tweak_ctx - Help for automatically tweaking requests
* @orig_req: Pointer to the original IO request
* @nand: Related NAND device, to have access to its memory organization
* @page_buffer_size: Real size of the page buffer to use (can be set by the
* user before the tweaking mechanism initialization)
* @oob_buffer_size: Real size of the OOB buffer to use (can be set by the
* user before the tweaking mechanism initialization)
* @spare_databuf: Data bounce buffer
* @spare_oobbuf: OOB bounce buffer
* @bounce_data: Flag indicating a data bounce buffer is used
* @bounce_oob: Flag indicating an OOB bounce buffer is used
*/
struct nand_ecc_req_tweak_ctx {
struct nand_page_io_req orig_req;
struct nand_device *nand;
unsigned int page_buffer_size;
unsigned int oob_buffer_size;
void *spare_databuf;
void *spare_oobbuf;
bool bounce_data;
bool bounce_oob;
};
int nand_ecc_init_req_tweaking(struct nand_ecc_req_tweak_ctx *ctx,
struct nand_device *nand);
void nand_ecc_cleanup_req_tweaking(struct nand_ecc_req_tweak_ctx *ctx);
void nand_ecc_tweak_req(struct nand_ecc_req_tweak_ctx *ctx,
struct nand_page_io_req *req);
void nand_ecc_restore_req(struct nand_ecc_req_tweak_ctx *ctx,
struct nand_page_io_req *req);
/**
* struct nand_ecc - Information relative to the ECC
* @defaults: Default values, depend on the underlying subsystem